The Molo Formation, deposited by coastal progradation on the inner Mid-Norwegian continental shelf, coeval with the Kai Formation to the west and the Utsira Formation in the North Sea

Tor Eidvin¹, Tom Bugge ² & Morten Smelror ³

¹Norwegian Petroleum Directorate, P.O. Box 600, N-4003 Stavanger, Norway.

²Pertra ASA, Nedre Bakklandet 58c, N-7014 Trondheim, Norway.

³Geological Survey of Norway, N-7491 Trondheim, Norway.

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Abstract

The Molo Formation (new) represents a characteristic depositional unit on the inner Mid-Norwegian continental shelf and extends along the coast for about 500 km from Møre to Lofoten. It was deposited by coastal progradation in a wave-dominated environment with extensive long-shore drift. The age and stratigraphic relationships have been heavily debated since it was discovered and first described nearly forty years ago. Based on new age information from exploration wells in the Draugen Field on the Trøndelag Platform, the Molo Formation is now determined to be of Late Miocene to Early Pliocene age. It is interpreted to be the proximal equivalent to the deeper marine Kai Formation in the Norwegian Sea and a lateral equivalent to the Utsira Formation in the North Sea. They were all deposited as a result of the compression and uplift of the mainland Norway in mid Miocene time. In this paper we describe and document the datings and formally define the Molo Formation as a new stratigraphic unit.

Introduction

The Molo Formation corresponds to the characteristic seismic unit which was informally called the “Delta” by Bugge et al. (1976) and later the “Frøyrygg formation” by Askvik & Rokoengen (1985, Figs. 1 and 2). The age assignment of the unit has varied from Eocene/Oligocene to Pliocene, thus being time equivalent to the Brygge, Kai or Naust formations. The formation is nearly exposed on the seabed and forms an approximately 500 km long ridge on the inner shelf from Møre to Lofoten (Fig. 1). Since the unit forms a potential wave breaker and is related to the Naust, Kai or Brygge formation, Gustavson & Bugge (1995) proposed the name “Molo” (Jetty) formation.

Fig. 1. The Molo Formation was deposited by coastal progradeation in the Late Miocene to Early Pliocene. It is situated on the inner part of the continental shelf and extends for 500 km from Møre to Lofoten. The isopach map is from Bullimore et al. (2005), and the map showing structural elements and seismic lines is from Brekke (2000).

In this paper we discuss its stratigraphic relationship and propose a Late Miocene to Early Pliocene age, which is coeval with most of the Kai Formation in the Norwegian Sea and most of the Utsira Formation in the North Sea. It has long been noted that it has high erosional resistance and therefore most probably is sand dominated. Bugge et al. (1976) proposed that it was deposited as a result of mainland uplift and erosion, and Rokoengen et al. (1995) classified the sediments as delta-like coastal deposits, probably formed in a wave-dominated environment with extensive long-shore drift. Exploration wells show that the proximal part of the unit consists mainly of quartzose and glauconitic sand. The distal part to the west consists mainly of glauconitic sand, silt and clay.

The unit was first described by Eldholm & Nysæther (1969) and Nysæther et al. (1969), and later by Bugge et al. (1976), Skarbø et al. (1983), Bugge et al. (1984), Askvik & Rokoengen (1985), Rokoengen et al. (1988), Sigmond (1992), Poole & Vorren (1993), Eidvin et al. (1995), Gustavson & Bugge (1995), Rokoengen et al. (1995), Henriksen & Vorren (1996), Henriksen & Weimer (1996), Eidvin et al. (1998a and 2000), Brekke (2000) and Bullimore et al. (2005). However, the age of the deposits is still disputed. A reason for this is that few wells and boreholes have sampled the deposits with high quality conventional cores or sidewall cores. Another reason is that samples from wells and boreholes from the proximal part of the unit seem to be barren of in situ fossils and only contain assemblages which we now interpret to represent caved and reworked material. We therefore made a new effort where we concentrated on identifying wells that penetrate the outer, more distal and potentially more fine grained part, although the entire Molo Formation is a proximal deposit. Many of the wells in the Draugen Field on the Trøndelag Platform (Fig. 1) seemed to have an optimal location, and wells 6407/9-1, 6407/9-2 and 6407/9-5 were re-analysed.

The obtained Late Miocene to Early Pliocene age contradicts the ages previously given by the biostratigraphic consultants as well as our previous datings of wells and boreholes from proximal parts of the formation. Our new study is based on investigation of ditch cutting samples from wells 6407/9-1, 6407/9-2 and 6407/9-5 by means of foraminiferal, dinoflagellate and strontium isotope analyses. Unfortunately, there are no other wells where we have succeeded in identifying what we believe represent in situ fossil assemblages, but in Appendix 1 we have presented our new investigations of wells from proximal parts of the Molo Formation including well 6510/2-1 (Vega High), 6610/3-1 (Nordland Ridge) and 6610/2-1S (Nordland Ridge). In Appendix 1 we have also presented and discussed previous datings of other boreholes which have sampled the Molo Formation.

The stratigraphic and depositional relationship between the Molo Formation and the Brygge, Kai and Naust formations have been long debated, consequently we have also put emphasis on its stratigraphic relationship. The Brygge to Naust succession has been re-analysed or re-evaluated in most of the relevant wells in the Norwegian Sea, and in Appendix 1 we have also presented new investigations of well 6508/5-1 and 6609/5-1 on the Nordland Ridge and well 6507/12-1 and 6609/11-1 on the Trøndelag Platform. These wells have been tied to seismic data and incorporated in a seismic stratigraphic framework. This is discussed below, together with a correlation with the coeval Utsira Formation in the North Sea. We consider the revised stratigraphy and depositional history to have important impact on maturation, migration and entrapment of petroleum in the area.

Fig. 2. Ultra high-resolution seismic line across the Molo Formation. There are three significant hiati shown; the brown line represent a gap from Early Oligocene to Early Miocene, the red line a gap from Early to Late Miocene, and the blue line a gap from mid Early to mid Late Pliocene.

In the main part of this paper we concentrate on the stratigraphic and depositional implications for the Molo Formation, but without going in depth we also include the same topics for the Brygge, Kai and Naust formations. Valuable studies of this succession were carried out in the Seabed Project of the Norwegian Deep Water Programme (Norwegian Deepwater programme 2004). Much of this work and a synthesis of the present and other studies were summed in a presentation by Bugge et al. (2004).

All well analyses and interpretations are documented in Appendix 1. In Appendix 2 we present a formal definition of the new Molo Formation. If not stated otherwise, all absolute ages in the present study, are based on Berggren et al. (1995), and all depths in the wells are expressed as metres below the rig floor (mRKB).

Previous age assessment of the Molo Formation

The Molo Formation was first sampled in 1982 by the Continental Shelf Institute (IKU and later Sintef Petroleum Research) in connection with their regional programme of mapping outcropping Cainozoic and Mesozoic rocks on the Mid-Norwegian continental shelf. Their defined seismic unit IX, corresponding to the delta-like Molo Formation, was sampled in the Nordland Ridge area with vibro corer, piston corer and grab at localities with very sparse Pleistocene – Holocene cover (Fig. 1). The vibro coring disturbed the sediments during sampling and made biostratigraphical analysing difficult. The samples contained a blend of Pleistocene and Holocene foraminifera and Oligocene and Eocene dinoflagellates. The Oligocene dinoflagellates were thought to be in situ fossils (Skarbø et al. 1983, Bugge et al. 1984).

Not far south of these boreholes the unit was sampled with ditch cuttings in the exploration well 6610/7-1 (Fig. 1). Poole & Vorren (1993) presented a dating of this well, and they recorded no in situ fossils in the sediments which correspond to the Molo Formation, but reported Middle Miocene foraminifera from the section immediately below. However, Eidvin et al. (1995, 1998a) recorded exclusively Lower-Middle Eocene fossils immediately below the barren Molo Formation.

Further north the exploration well 6610/3-1 (Fig. 1) sampled the Molo Formation with sidewall cores. A biostratigraphical investigation of five sidewall cores of high quality was presented by Eidvin et al. (1995, 1998a). Based on analyses by means of foraminifera, dinoflagellates and strontium isotopes they concluded on an Early Oligocene age for the deposits. However, the palynological residues were recently re-analysed and Early Miocene dinoflagellates were now also recorded. These new investigations are presented in Appendix 1.

Henriksen & Vorren (1996) interpreted the Molo Formation to be Early Pliocene in age or alternatively Early Oligocene. The Early Pliocene age was based on regional stratigraphic considerations and a possible correlation with the global sea-level curve of Haq (1991). The Early Oligocene age was based on the datings of Skarbø et al. (1983) and Eidvin et al. (1995). Henriksen & Weimer (1996) held on to the Early Pliocene age.

The exploration well 6610/2-1S was drilled on the Nordland Ridge just to the southwest of well 6610/3-1 (Fig. 1). In this well the sediments immediately below the Molo Formation were sampled with ditch cuttings. The deposits have been given an Early Oligocene age based on foraminiferal, dinoflagellate and strontium isotope analyses (Appendix 1).

In the exploration well 6510/2-1 on the Vega High to the south (Fig. 1) the Molo Formation was sampled with sidewall cores. Unfortunately, the cores were not of very high quality and the in situ sampled material was mixed with caved sediments. The cores were investigated by means of foraminifera, dinoflagellate and strontium isotope analyses and the deposits were assigned an Early Miocene age in Appendix 1.

This was the status when we started re-analysing the Draugen field wells.

Regional framework

In order to embrace the Molo Formation both in space and stratigraphically, we here discuss the entire period from the opening of the Norwegian Sea in earliest Eocene to the Present day, keeping focus on the Molo Formation. This period spans deposition of the Brygge Formation sediments (Hordaland Group) from Early Eocene to Early Miocene, the Kai/Molo formations from Middle Miocene to Early Pliocene (approximately 14-4 Ma) and the Naust Formation from the Late Pliocene to Present (<2.8 Ma). The Kai/Molo and Naust formations belong to the Nordland Group (Fig. 3).

Fig. 3. Chronogram with a selection of the studied wells. Vertical axis is in Ma. We note that the Molo and Kai formations in the Norwegian Sea and the Utsira Formation in the North Sea all belong to the time interval Middle Miocene to Early Pliocene, i.e., above the mid Miocene unconformity. The stratigraphy in well 24/12-1 is after Rundberg and Eidvin (2005) and Eidvin & Rundberg (this volume). The stratigraphy in well 34/8-3A is modified after Eidvin & Rundberg (2001). The stratigraphy in well 6506/12-4 and 6607/5-1 is modified after Eidvin et al. (1998a) and the stratigraphy in borehole 6704/12-GB1 is modified after Eidvin et al. (1998b).

After regional uplift during the Palaeocene with shallow marine conditions and subaerial exposure of large areas, the entire margin subsided and the sea transgressed the margin and part of the mainland. The Brygge Formation was deposited in this period and is clay-dominated on the present day shelf and ooze dominated in the distal, deeper marine Møre and Vøring basins. Deposition was concentrated in the Møre Basin and the outer part of the Vøring Basin, with thicknesses of 600-1000 m and 500-700 m, respectively (Norwegian Deepwater programme 2004). The ooze sediments are characterised by small-scale polygonal faulting, interpreted to be caused by compaction and water escape. The Brygge Formation sediments have some places been remobilised by different processes. Sliding is observed occasionally on the shelf and palaeoslope, while mounding and diapirism are more frequent in the basins, for instance around the Vema Dome/Nyk High. Liquefaction and vertical squeezing has been observed in crater-like forms within the Storegga Slide area, west of Haltenbanken (Vigrid) area and in the Vema Dome area (Riis et al. 2005). All reactivation seems to have occurred during or after deposition of the glacially influenced Naust Formation sediments.

During the Oligocene there seems to have been tectonic activity resulting in compression and uplift of basin flanks and the landward part of the margin. It culminated in a regional uplift in the mid Miocene (e.g. Brekke 2000, Løseth & Henriksen 2004), corresponding to the “mid Miocene unconformity”. The exact dating of this has been discussed, but from well data in the North Sea, Rundberg & Eidvin (2005) have placed it at the Early-Middle Miocene transition. There is a significant hiatus in most wells on the middle and inner margin (Fig. 3). The missing section frequently spans from Lower/Middle Eocene to Middle Miocene. The Molo and Kai formations rest on top of the Middle Miocene unconformity.

In wells 6407/9-3 and -5 there is an up to 22 m thick section of Lower Miocene sediments. It is wedge shaped and overlies a clear erosional unconformity (Fig. 4). The stratigraphic gap in well 6407/9-5 ranges from Lower Oligocene to Lower Miocene. A fine grained Lower Miocene unit in the northern North Sea is bounded below and above by similar unconformities (Rundberg & Eidvin 2005). About 50 km northeast of the Draugen Field another wedge with the same stratigraphic position and appearance has been observed (Fig. 5). It has not been dated, but from comparisons it might be suggested to be similar to the one at the Draugen Field. Stratigraphically and age wise, the wedge belongs to the Brygge Formation. The unconformity below the wedge seems to represent more active erosion than the Mid Miocene unconformity on top. There are few signs of erosional products related to any of the two hiati, which indicates that the Mid Miocene Unconformity is more related to non-deposition than being a major erosional episode.

Fig. 4. The Molo Formation at the Draugen Field. Note the Upper Brygge Formation wedge of Early Miocene age between the brown and red line. It rests on a clear erosional surface with the mid Miocene unconformity (red) on top. Fig. 4a is a dip line and 4b is a strike line.

Fig. 5. The Molo Formation 50 km north of Draugen. Although not dated the unit between brown and red line is probably equivalent to the upper Brygge Formation unit at Draugen.

After the Mid Miocene uplift, sedimentation resumed on the outer and middle part of the margin. Clay-dominated sediments belonging to the Kai Formation are dated as late Middle Miocene and younger. On the middle/inner part of the shelf, we have dated the sand-dominated Molo Formation as Late Miocene and Early Pliocene. This implies that the Molo Formation is of the same age as the Kai Formation, but may lack the oldest (Middle to early Late Miocene) part (Fig. 3). Based on dating and seismic correlation we interpret the Molo Formation to be the proximal equivalent to the more distally deposited Kai Formation (Fig. 6). A more thorough description of the Molo Formation is given below.

Fig. 6. NW-SE line on northern Haltenbanken showing the stratgraphic relationships of the Brygge, Kai and Molo formations. The Molo Formation is the proximal time equivalent to the Kai Formation. Well correlation and dating of the formations is essential to obtain the correct definition.

On the shelf and slope down to the deeper Møre and Vøring basins the Kai Formation is overall clayey with ooze in the basinal part. It has a similar polygonal fault pattern as the Brygge Formation, although in detail there are differences in seismic facies between the two units. After deposition of the Kai and Molo formations, the climate cooled, glaciers started to grow and the glaciations in Scandinavia were introduced. Based on the amount of ice-rafted debris in deep-sea cores (Fronval & Jansen 1996), it is common to interpret the first glacial advances to the Norwegian coast in the Late Pliocene, approximately 2.8 million years ago. Until approximately 1.5 Ma, the glaciers were probably restricted to the mainland and did not pass on to the shelf (Bugge et al. 2004, Rise et al. 2005). Up to approximately 0.5 Ma glaciers periodically advanced on to the shelf, and after 0.5 Ma massive glaciers covered the entire shelf during three glacial periods.

The thick Naust Formation was deposited during a comparatively short time and contains few significant biostratigraphical events. Fossil analyses of ditch cuttings are not sufficient to obtain a detailed stratigraphy in this formation. Only paleomagnetic investigations of cored sections can give satisfactory results, but such materials are scarce. However, our investigation indicates that there generally is a hiatus below the Naust Formation. Sediments representing late Early to early Late Pliocene are identified, with certainty, only on the Vøring Plateau where these deposits are cored in ODP/DSDP-drillings.

Characteristics of the Molo Formation

The Molo Formation has a unique seismic character, particularly on high-resolution seismic data. The Continental Shelf Institute (IKU and later Sintef Petroleum Research) mapped it in detail by acquiring a regular grid of single channel sparker data on the Mid-Norwegian continental shelf (Rokoengen et al. 1988). The seismic facies is not always easy to recognise on conventional multi channel 2D data and correct correlation and mapping of the outcrop position is often benefiting from correlation with the map published by Rokoengen et al. (1988).

The Molo Formation was deposited from the coast off Møre (63^o15’N) to the Lofoten Islands (67^o50’ N), i.e., over a distance of about 500 km (Fig. 1). It represents a prograding system comprising fairly steep clinoforms (5-15 degrees). In the inner part top set beds are normally missing and we interpret this to be the result of later erosion. The outer part normally includes the top sets. The bottom sets are preserved all through. Henriksen & Weimer (1996) mapped the northern part of the Molo Formation in detail and subdivided it in up to 38 sub sequences (Fig. 7). There are clear evidences for forced regression during the time of deposition, thus demonstrating relative lowering of sea level. This could be due to uplift rather than to lowering of the eustatic sea level. We prefer uplift for several reasons. The coincidence with the mid Miocene compression and uplift event seems to explain why such a significant volume of sediment was eroded and re-deposited during a reasonably short period. The in situ fossil assemblages in the Draugen Field area indicate shallow shelfal environment, and the assemblages in the proximal wells are reworked. The prograding clinoforms suggest fairly high-energy coastal environment. The sandy lithology also supports such an interpretation. Some of the wells in proximal parts and some of the vibro cores acquired by IKU contain deep red to yellow oxidized sand similar to the deposits cored from the Palaeocene Tare Formation outcropping 10-15 km to the east of the Molo Formation (Bugge et al. 1984), and similar to the sediment recorded in the Tare Formation in well 6510/2-1 (Vega High, Appendix 1). Erosion and recycling of these sediments are better explained by uplift to the east than by eustatic lowering of sea level.

Fig. 7. Henriksen and Weimar (1996) divided the Molo Formation in 38 sub sequences in the north, south of the Lofoten Islands. The bottom sets are generally preserved, while the top sets are frequently eroded or missing due to forced regression.

It has not been possible to identify any particular entry points for sediments being fed into the Molo Formation. This may be explained by a regional uplift of the mainland and eastern basin margin exposing the entire coastline to erosion. Long-shore currents probably redeposited and redistributed the sediments. All the way up towards Lofoten, the Molo Formation seems to have been deposited from the east. An exception is the northern part where the strike turns around to a more westerly direction, thus indicating that the Røstbanken/Røst High area off Lofoten was a source area. This represents the northern termination of the Molo Formation.

Dating of the Molo Formation and correlation between the Molo, Kai and Utsira formations

The re-analysing of the Molo Formation in the Draugen Field wells 6407/9-1, 6407/9-2 and 6407/9-5 shows the occurrence of in situ Late Miocene and Early Pliocene Bolboforma, planktonic and benthic foraminifera and dinoflagellate cysts. Datings by means of strontium isotope stratigraphy support the ages given by biostratigraphic correlations. Upper Miocene sediments are only recorded in well 6407/9-5. Sediments given a general Late Miocene to Early Pliocene age are observed in well 6407/9-1. Lower Pliocene deposits are recorded in all the wells (Figs. 10 and A1-A6).

In the present study we have investigated the Kai Formation in well 6507/12-1, 6508/5-1, 6609/5-1 and 6609/11-1 (Figs. A12-A16). In previous studies we have invested the Kai Formation in well 6506/12-4 on the Halten Terrace (Eidvin et al. 1998a), well 6607/5-1 on the Utgard High (Eidvin et al. 1998a) and in corded sections of borehole 6704/12-GB1 at the Gjallar Ridge (Eidvin et al. 1998b, Fig. 1). The Utsira Formation has been investigated in wells 15/12-3, 15/9-A-23, 16/1-2, 24/12-1 and 25/10-2 in the southern Viking Graben (North Sea, Rundberg & Eidvin 2005 and this volume) and in wells 34/8-1, 34/8-3A, 34/7-1, 34/4-7, 34/4-6, 34/2-4 and 35/11-1 in the northern North Sea (Eidvin & Rundberg 2001, Fig. 8).

Fig. 8. The Molo Formation is time equivalent to the Utsira in the North Sea. The Molo Formation was deposited from the east, while the Utsira Formation was deposited both from the Shetland Platform in the west and the Sognefjorden area in the east. The extent of the Utsira Formation is according to Rundberg & Eidvin (2005), and the isopach map of the Molo Formation is according to Bullimore et al. (2005).

Fig. 9. Geoseismic section showing that Molo and Kai formations are proximal and distal equivalents to each other. The mid Miocene unconformity separates the Kai and Molo formations from the underlying Brygge Formation.

Fig. 10. Correlation of fossil assemblages and zones between well 6407/9-5, 6407/9-1, 6407/9-2 as well as from the wells to King's (1989) North Sea fossil zonation and to the fossil zonation of the ODP sites 642 and 643 on the Vøring Plateau (Spiegler & Jansen 1989, Müller & Spiegler 1993). The IRD curve is after Jansen & Sjøholm (1991) and Fronval & Jansen (1996).

In the lower part of all formations, except in the northern North Sea Quadrant 34 and 35, we were able to recognise planktonic fossil assemblages which include the important index fossil of the genus Bolboborma. These can be correlated with the Bolboforma zonation of (Spiegler & Müller 1992, Müller & Spiegler 1993), established through the ODP/DSDP drillings in the North Atlantic and the Norwegian Sea. Correlation with these zones may yield quite accurate ages, since the zones are of short duration and are calibrated using nannoplankton and paleomagnetic data. The B. metzmacheri assemblage recorded in lower part of the Utsira Formation in well 25/10-2 (Eidvin & Rundberg, this volume), in the lower to middle part of the Kai Formation in well 6508/5-1, 6609/5-1 and 6607/5-1 (Eidvin et al. 1998a) and in the lower part of the Molo Formation in well 6407/9-5 can be correlated with the B. metzmacheri  Zone of Spiegler & Müller (1992) and Müller & Spiegler (1993, Figs. 11, A1, A14 and A15). This zone is described from sediments with an age of approximately 10.0-8.7 Ma in the North Atlantic and the Norwegian Sea.

Fig. 11. Correlation of planktonic fossil assemblages and zones between well 25/10-2 (southern Viking Graben, North Sea), 6407/9-5 (Trøndelag Platform, Norwegian Sea continental shelf), 6507/12-1 (Trøndelag Platform, Norwegian Sea continental shelf) and 6508/5-1 (Nordland Ridge, Norwegian Sea continental shelf) as well as from the wells to the fossil zonation of the ODP sites 642 and 643 on the Vøring Plateau (Spiegler & Jansen 1989, Müller & Spiegler 1993). The correlation lines for the Bolboforma metzmacheri assemblage are shown in green. The IRD curve is after Jansen & Sjøholm (1991) and Fronval & Jansen (1996).

The B. fragori assemblage in the base of the Utsira Formation in well 24/12-1 and 25/10-2 (Eidvin & Rundberg, this volume), the B. subfragori assemblage in the base of the Kai Formation in well 6609/11-1 and the B. subfragori - B. fragori assemblage in well 6507/12-1, 6508/5-1 and 6609/5-1 can be correlated with the B. fragori/B. subfragori Zone of Spiegler & Müller (1992) and Müller & Spiegler (1993,  Figs. 11, 12, A12, A14, A15 and A16). This zone is known from deposits with an age of approximately 11.9-10.3 Ma in the North Atlantic and the Norwegian Sea. Immediately below the Utsira Formation (lower part of the Nordland Group) in well 24/12-1 and 25/10-2 (Eidvin & Rundberg, this volume) we recorded the B. badenensis and B. reticulate assemblages. These can be correlated with the B. badenensis/B. reticulata Zone of Müller & Spiegler (1993) which they recognised in deposits with an age of 14-11.9 Ma in the North Atlantic and the Norwegian Sea. This unit is also present in the base of the Kai Formation, immediately above the mid Miocene seismic reflector in well 6507/12-1 (Trøndelag Platform), and the upper part of the unit is recorded in the Kai Formation in borehole 6704/12-GB1 (Gjallar Ridge, Eidvin et al. 1998b, Figs. 8, 11 and 12).

Fig. 12. Correlation of the fossil assemblages and zones between well 24/12-1 (southern Viking Graben, North Sea), 34/8-3A (northern North Sea), 6407/9-5 (Trøndelag Platform, Norwegian Sea continental shelf) and 6609/11-1 (Trøndelag Platform, Norwegian Sea continental shelf) as well as from the wells to King's (1989) North Sea fossil zonation and to the fossil zonation of the ODP sites 642 and 643 on the Vøring Plateau (Spiegler & Jansen 1989, Müller & Spiegler 1993). The IRD curve is after Jansen & Sjøholm (1991) and Fronval & Jansen (1996).

In the lower and middle part of the Utsira Formation in well 24/12-1 and 25/10-2, we recorded the calcareous benthic U. venusta saxonica assemblage. This assemblage is also present in the lower to middle part of the Kai Formation in well 6609/11-1, 6508/5-1, 6507/12-1 and 6609/5-1 (Figs. 11, 12, A12, A14, A15 and A16). According to King (1989) is U. venusta saxonica known from Upper Miocene to Lower Pliocene deposits in the North Sea area. This unit is not present in the Molo Formation in well 6407/9-5. This may be because there is a hiatus within the unit, but it is most likely due to depositional water depth or other environmental factors. Uppermost in the Utsira Formation in well 24/12-1 we recorded the calcareous benthic M. pseudotepida assemblage. This unit is also recognised in the upper part of the Molo Formation in well 6407/9-5 and in the lower part of this formation in well 6407/9-2 where a smaller section of this assemblage is present (Figs. 10 and 12). According to King (1989) is M. pseudotepida known from the uppermost Upper Miocene to the lowermost Upper Pliocene in the North Sea area. M. pseudotepida is not recorded in any well where we have investigated the Kai Formation. This is probably due to the fact that M. pseudotepida was a shallow water dweller (Skarbø & Verdenius 1986). The upper parts of the Utsira and Molo formations were probably deposited on the inner shelf unlike the Kai Formation, which was probably deposited on the middle and outer shelf.

Uppermost in the Molo Formation we recorded a calcareous benthic E. pygmeus assemblage or E. pygmeus – S. bulloides assemblage. An E. pygmeus assemblage is also recognised in the upper part of the Kai Formation in well 6507/12-1 and 6508/5-1 (Figs. 10, A14 and A16). An E. pygmeus – G. subglobosa assemblage is seen in the upper part of the Kai Formation in well 6607/11-1, and a C. telegdi - E. pygmeus assemblage was recorded in the upper part of the Kai Formation in well 6607/5-1 (Utgard High) and 6506/12-4 (Halten Terrace, Eidvin et al. 1998a). E. pygmeus is also known from the upper part of the Utsira Formation in well 24/12-1 and 25/10-2 (Eidvin & Rundberg, this volume) and 34/8-3A (Eidvin & Rundberg 2001, Fig. 8) and in several other wells where the Utsira Formation has been investigated.    

Strontium isotope stratigraphy, based on analyses of calcareous index fossils, can also be used for correlation between the formations. The four intervals analysed for strontium isotopes in the Molo Formation in well 6407/9-5 gave ages varying from approximately 5.8 to 5.2 Ma (Table 1, Fig. A1). Such ages fit quite well with the ages suggested by biostratigraphic correlation for the upper part of the unit. However, it is somewhat younger than the age suggested by correlation of the occurrence of B. metzmacheri, in the lower part of the unit, to the deep sea record (approximately 10.0-8.7 Ma). One sample taken from the upper part of the Molo Formation in well 6407/9-1 gave an age of approximately 6.0 Ma (Table 1, Fig. A3). It should be noted that all the studied Draugen wells (6407/9-1, /9-2 and /9-5) are distally located in the Molo Formation and did not penetrate the oldest parts of the formation (Fig. 4a). The Molo Formation could thus comprise somewhat older sediments than the ones dated.

One sample taken from the middle part of the Kai Formation in well 6609/11-1 gave an age of approximately 6.3 Ma (Table 1, Fig. A12). Two samples taken from one interval in the middle part of the Kai Formation in well 6508/5-1 gave ages of approximately 6.4 and 6.0 Ma (Table 1, Fig. A14). Two samples taken from an interval in the lower half of the Kai Formation in well 6506/12-4 (Halten Terrace, Table 1, Fig. 1) gave both ages of approximately 5.3 Ma. Several samples taken from the lower half of the Kai Formation in well 6607/5-1 (Utgard High, Table 1, Fig. 1) gave ages varying from 6.9 to 5.1 Ma. The oldest age is recorded from the lowermost of these samples occurring in a B. metzmacheri assemblage. One sample close to the base of the Kai Formation in the same well gave an age of approximately 11.0 Ma. This sample occurs in a B. subfragori/B. fragori assemblage (Eidvin et al. 1998a, Nødtvedt 1999). Two samples close to the base of the Kai Formation in well 6507/12-1 (Halten Terrace), which also occur in a B. subfragori/B. fragori assemblage, gave approximately 8.0 and 10.9 Ma (Table 1, Fig. A16). One sample taken from the lower half of the Kai Formation in well 6609/5-1 gave an age of approximately 9.6 Ma (Table 1, Fig. A15). This sample occurs in a B. laevis assemblage, which is known from deposits with an age of approximately 10.3-10.0 Ma in the Norwegian Sea and in the North Atlantic (Spiegler & Müller 1992, Müller & Spiegler 1993).

Several samples taken from the thin unit of glauconitic sand, which represents the Utsira Formation in well 34/8-1, 34/4-6 and 34/4-7 (northern North Sea, Fig. 8), gave ages varying from 5.6 to 5.0 Ma (Eidvin & Rundberg 2001).

A large number of strontium isotope ages were obtained from the Utsira Formation in the wells 15/12-3, 15/9-A-23, 16/1-2, 24/12-1 and 25/10-2 from the southern Viking Graben. In these wells mainly mollusc fragments were used for the analyses since the deposits are very rich on molluscs, but not so rich on foraminiferal index fossils. We were not able to identify the mollusc fragments and consequently we could not exclude caved or reworked shells. The analyses gave some variation in age, and it was obvious that some caved and reworked shells were analysed. However, most samples in upper parts, i.e. parts which according to the biostratigraphic correlation are of Early Pliocene age, gave ages varying from approximately 5 to 4 Ma. Most samples from the lower parts, i.e. parts which according to biostratigraphic correlation are of Late Miocene age, gave ages varying from approximately 12 to 5 Ma (Eidvin & Rundberg, this volume).

Lithologically there are also large similarities between the Molo Formation in wells from the Draugen Field (Trøndelag Platform) and the Utsira Formation in wells from the Snorre and Visund fields in the northern North Sea (Fig. 8). The Utsira Formation in these wells consists mainly of very dark glauconitic sand (Eidvin & Rundberg 2001). The same kind of sand is also present in the Molo Formation in the Draugen Field, but these deposits also contain some clay and silt. East of the Snorre and Visund fields in the northern North Sea the glauconitic beds probably drape over the main Utsira sand (Eidvin & Rundberg 2001). The main Utsira sand is investigated in well 35/11-1, and the sediments consist of white, coarse, well sorted quartzose sand which probably originates from the Sognefjord area. The deposits are nearly barren of micro fossils, but the few recorded forms point to a Late Miocene age (Eidvin & Rundberg 2001). The Utsira Formation, in wells from the southern Viking Graben, also contains mainly quartzose sands with some thin glauconite beds. These sands are also mainly whitish, but in some section the grains are slightly rust tinted due to oxidation of the glauconite. The quartzose sands from the North Sea are, however, quite different from the quartzose sands recorded in wells and boreholes from the proximal part of the Molo Formation in the Nordland Ridge area. These deposits consist of red to dark yellow, probably lateritic sand, with well rounded, tinted pebbles. These differences indicate that the sandy sediments on the Nordland Ridge were originally deposited during a period of much warmer climate and were later redeposited into the Molo Formation.

In Eidvin et al. (1998a, 2000) the Cibicides telegdi-Eponides pygmeus-Neogloboquadrina atlantica (dextral) zone in the upper part of the Kai Formation in well 6607/5-1 (Utgard High) and the Nonion affine – Neogloboquadrina atlantica (dextral) zone and the Cibicides telegdi-Eponides pygmeus-Neogloboquadrina atlantica (dextral) zone in upper part of the Kai Formation in well 6506/12-4 (Halten Terrace, Fig. 1) were given a Late Miocene age based on the occurrence of N. atlantica (dextral). However, N. atlantica (dextral) is known to occur in both uppermost Upper Pliocene and Upper Miocene on the Vøring Plateau (Spiegler & Jansen, 1992; Müller & Spiegler, 1993). These stratigraphical units most likely correlate with the foraminiferal assemblages in the upper part of the Kai Formation in the wells 6609/11-1 and 6507/12-1 (Trøndelag Platform) and the upper part of the Molo Formation in the wells 6407/9-1, /9-2 and /9-5 (Trøndelag Platform) and are most likely of Early Pliocene age (Fig. 1). The occurrence of N. atlantica (dextral) is probably caved from Upper Pliocene deposits or reworked from Upper Miocene deposits. A Late Miocene age for the lower part of the Kai Formation in well 6607/5-1 and 6506/12-4 were verified by strontium isotope analyses (Nødtvedt 1999).

In addition to regional uplift the deposits of the Molo, Kai and Utsira formations are probably also a response to the Neogene climatic evolution of regions surrounding the North Atlantic and the Norwegian-Greenland Sea. The first signs of Northern Hemisphere glaciation, recorded in ODP sites on the Vøring Plateau probably originated in Greenland and date to ~12.6 Ma (latest Middle Miocene, Fronval & Jansen 1996). This event is associated with a global reorganisation of ocean circulation which occurred at the same time (Wright & Miller 1993), and marks the onset of continuous northern component deep water and the subsequent increased water mass exchange between the sub-Arctic and the world ocean. Although the onset of a more erosive regime on the Norwegian mainland appears to be related to climatic development in the Miocene, there is so far no evidence for the existence of glaciers on the eastern seaboard of the Norwegian-Greenland Sea during this period. There was a significant increase in the supply of ice-rafted debris to the deep ocean, associated with climatic cooling in the latest Miocene (Messinian event, Jansen & Sjøholm 1991, Fronval & Jansen 1996). To date, however, firm evidence for the existence of glaciers has been documented only from Greenland (Larsen et al. 1994, Jansen, Raymo, Blum et al. 1996), but small ice caps may also have been present in the highest areas of Fennoscandia. 

Conclusions

During the Oligocene there seems to have been tectonic activity resulting in compression and uplift of basin flanks and landward part of the margin. It culminated in a regional uplift in the mid Miocene. There is a significant hiatus in most wells on the middle and inner margin (Fig. 3). The missing section spans from Lower/Middle Eocene to Middle Miocene. The Molo Formation was deposited by coastal progradation as a result of this uplift. The sediments are sandy, shallow marine with a typical clinoform geometry. Distally to this the Kai Formation was deposited in a generally deeper marine setting. There was often a bypass zone between the Molo and the Kai formations. (Fig. 9).

In wells 6407/9-3 and /9-5 there is an about 20 m thick section of Lower Miocene sediments. It is wedge shaped and overlies a clear erosional unconformity (Fig. 4). The stratigraphic gap ranges from Lower Oligocene to Lower Miocene. Stratigraphically and age wise, the wedge belongs to the Brygge Formation. The unconformity below the wedge seems to represent more active erosion than the Mid Miocene unconformity on top. There are few signs of erosional products related to any of the two hiati, which indicates that the Mid Miocene Unconformity is more related to non-deposition than being a major erosional episode. After the Mid Miocene uplift clay-dominated sediments belonging to the Kai Formation were deposited on the outer and middle part of the margin. On the middle/inner part of the shelf sand-dominated sediments of the Molo Formation were laid down.

The Molo Formation was deposited from the coast off Møre (63^o15’N) to the Lofoten Islands (67^o50’ N), i.e., over a distance of about 500 km (Fig. 1). It represents a prograding system comprising fairly steep clinoforms (5-15 degrees). In the inner part top set beds are normally missing and we interpret this to be the result of later erosion. The outer part somewhere includes the top sets, but forced regression frequently prevented top sets from being deposited. The bottom sets are preserved all through.

A re-dating of the Molo Formation in the distal Draugen Field wells 6407/9-1, 6407/9-2 and 6407/9-5, based on analyses of planktonic and benthic foraminifera, dinoflagellate cysts and strontium isotopes, gave the unit a Late Miocene to Early Pliocene age. This age contradicts the ages previously given to this unit by biostratigraphic consultants. It also contradicts an Early Oligocene age which was obtained by our previous investigation of wells and boreholes from the proximal parts of the formation.

We are able to correlate the Molo Formation to the Kai Formation to the west and the Utsira Formation in the North Sea by means of the benthic and planktonic fossil and strontium isotope data. The most complete section of the Molo Formation was found in well 6407/9-5, and especially noteworthy is the recording of the planktonic Bolboforma metzmacheri assemblage in the lower part of the unit in this well. Correlation of shelfal fossil assemblages with the deep ocean Bolboforma zones may yield quite accurate ages, since the zones are of short duration and are calibrated using nannoplankton and paleomagnetic data. Spiegler & Müller (1992) and Müller & Spiegler (1993) were able to give their B. metzmacheri Zone an accurate age of 10.0-8.7 Ma. In addition to well 6407/9-5, we have recorded a B. metzmacheri assemblage in the lower part of the Utsira Formation in well 25/10-2 (Eidvin & Rundberg, this volume) and in the lower to middle part of the Kai Formation in well 6508/5-1, 6609/5-1 and 6607/5-1 (Figs. 11, A14 and A15).

At the base of the Utsira Formation in well 25/10-2 and near the base in well 24/12-1 and at the base or near the base of the Kai Formation in well 6609/11-1, 6508/5-1, 6609/5-1 and 6507/12-1 we were able to record a Bolboforma fragori assemblage which correlates with the B. fragori/B. subfragori Zone of Spiegler & Müller (1992) and Müller & Spiegler (1993, 11.9-10.3 Ma). In the base of the Kai Formation in well 6507/12-1 we were also able to record a Bolboforma badenensis/B. reticulata assemblage which correlates with the B. badenensis/B. reticulata Zone of Spiegler & Müller (1992) and Müller & Spiegler (1993). This zone is the oldest of the Bolboforma zones in the North Atlantic and the Norwegian Sea and are given an age of 14-11.9 Ma. In the southern Viking Graben, North Sea, the B. badenensis/B. reticulate assemblage is recorded in a number of wells in the fine grained deposits at the base of the Nordland Group, just below the Utsira Formation. However, in well 24/12-1 and 15/12-3 the uppermost part of the B. badenensis/B. reticulata assemblage is within the lowermost part of the Utsira Formation (Eidvin & Rundberg, this volume). This implies that the oldest part of both the Utsira Formation and the Kai Formation is older than the oldest sediment we were able to record from the Molo Formation in the Draugen Field wells (the oldest parts were not penetrated). It also indicates that the oldest part of the Kai Formation is slightly older than the oldest part of the Utsira Formation (Fig. 3), although it should be noted that none of the wells penetrated the oldest parts.  

Appendix 1

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Investigation of the Molo Formation

Stratigraphy and lithology of well 6407/9-1, 6407/9-2 and 6407/9-5 in the Draugen Field on the Trøndelag Platform

Well locations, material and methods

Well 6407/9-1 (64º21’56.14’’N, 07º47’20.86’’E), 6407/9-2 (64º24’1.31’’N, 07º48’11.26’’E) and 6407/9-5 (64º16’42.35’’N, 07º44’14.66’’E) were drilled in the southern distal part of the Molo Formation in the Draugen Field (Trøndelag Platform, Fig. 1). A number of 30 ditch cutting samples from well 6407/9-1, 15 ditch cutting samples from well 6407/9-2 and 25 ditch cutting samples from well 6407/9-5 were used for the study. All the samples were analysed for foraminifera and Bolboforma and in some sections also for pyritized diatoms. Nine samples were analysed for dinoflagellates in well 6407/9-1, 14 samples in well 6407/9-2 and 25 samples in well 6407/9-5. For analyses of foraminifera, Bolboforma and diatoms 50-100 g material were used. The micropalaeontological identification was carried out in the 106- to 500-mm fraction. The fractions <106 mm and >500-mm were also inspected. Approximately 300 individuals were picked from each sample. In order to optimise identification of the assemblages, a number of samples rich in terrigenous grains were gravity-separated in heavy liquid. In such cases, 1000-1500 individuals were analysed in fossil rich samples. Palynomorphs were extracted from 20-30 g material, using conventional preparation methods involving removal of carbonates and silica by HCL and HF, respectively. The organic residues were subsequently oxidised with nitric acid to remove pyrite and some of the amorphous organic matter.

Micropalaeontological assemblages

The Upper Miocene and Pliocene sections contain rich to moderately rich faunas of mainly calcareous benthic and planktonic foraminifera. In addition the Upper Miocene (well 6407/9-5) contains a moderately rich assemblage of Bolboforma. The fossil assemblages in the Oligocene and Lower Miocene (well 6407/9-5) sections are dominated by radiolaria, pyritized diatoms and sponge spicules, but contain also sparse faunas of calcareous benthic foraminifera and some agglutinated foraminifera. It is supposed that the faunal turnover at the mid-Miocene unconformity reflects a change in depositional conditions from shallow water (above) to deeper water (below).

Well 6407/9-5

Benthic foraminiferal assemblages

ELPHIDIELLA HANNAI ASSEMBLAGE

Definition: The top of the assemblage extends to the uppermost investigated sample (620 m). The base is marked by the highest/youngest consistent occurrence of Eponides pygmeus.

Depth range: 620-670 m.

Material: Five ditch cutting samples.

Age: Late Pliocene.

Lithostratigraphic unit: Naust Formation.

Correlation: Zone NSB 15 of King (1989), Cibicides grossa zone of Stratlab (1988) and Zone NSR 12 B of Gradstein & Bäckström (1996).

Description: This interval contains a rich benthic fauna of mainly calcareous foraminifera. Elphidium excavatum and Cassidulina teretis occur most frequently. Cibicides lobatulus, Elphidium albiumbilicatum and Bulimimina marginata are also common. Other important species include Elphidiella hannai, Cibicides grossus, Nonion affine, Cassidulina reniforme and Cibicides scaldisiensis (Fig. A1).

Remarks: With the exception of E. hannai and C. grossus all the in situ benthic foraminifera are extant species. According to King (1989) E. hannai and C. grossus are found in the northern North Sea in Upper Pliocene to lower Pleistocene deposits. According to King (1989) the first appearance datums (FADs) of these species are considerably higher than the Lower/Upper Pliocene boundary (3.56 Ma). C. grossus is, however, recorded in deposits as old as the late Middle Miocene on the Vøring Plateau (T. Eidvin, unpublished data) and as old as the Late Miocene in the Netherlands. However, E. hannai is known from Upper Pliocene deposits in the latter area (Doppert 1980).

EPONIDES PYGMEUS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest consistent occurrence of E. pygmeus. The base is marked by the highest/youngest occurrence of Monspeliensina pseudotepida.

Depth range: 670-710 m.

Material: Four ditch cutting samples.

Age: Early Pliocene.

Lithostratigraphic unit: Molo Formation.

Correlation: Probably Cibicides telegdi – Eponides pygmeus – Neogloboquadrina atlantica (dextral) zone of Eidvin et al. (1998a) and probably lower part of Melonis – Trifarina zone of Stratlab (1988).

Description: This assemblage contains a rich benthic fauna of mainly calcareous foraminifera. N. affine and C. teretis occur most frequently. Other important taxa includes E. pygmeus, Loxostomoides lammersi, Sigmilopsis schlumbergeri (agglutinated), Quinqueloculina seminulum, B. marginata, C. lobatulus, Angulogerina fluens and Globocassidulina subglobosa (lowermost sample, Fig. A1).

Remarks: Most of the recorded benthic specimens are known from sediments from almost the entire Neogene. However, E. pygmeus is described from the Oligocene in Denmark and Germany (Grossheide & Trunko 1965, Hausmann 1964, Kummerle 1963, Ulleberg 1974). This species is recorded in deposits from the Oligocene to the Lower Pliocene in the North Sea and on the Norwegian Sea continental shelf (Stratlab 1988, Eidvin et al. 1998a, Eidvin & Rundberg 2001 and Eidvin & Rundberg this volume). Since taxa no older than earliest Late Miocene are recorded in the immediately underlying assemblage, this assemblage is most likely of Early Pliocene age.

MONSPELIENSINA PSEUDOTEPIDA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of M. pseudotepida. The base is marked by the highest/youngest common occurrence of G. subglobosa.

Depth range: 710-750 m.

Material: Four ditch cutting samples.

Age: Early Pliocene.

Lithostratigraphic unit: Molo Formation.

Correlation: Subzone NSB 14a of King (1989), Zone NSR 12A of Gradstein & Bäckström (1996).

Description: This interval contains a moderately rich benthic fauna of mainly calcareous foraminifera. There are somewhat fewer specimens than in the immediately overlying unit. No species are common, but important taxa include M. pseudotepida, G. subglobosa, L. lammersi, Textularia truncate (agglutinated), Sphaeroidina bulloides (lower part), Cibicidoides limbatosuturalis (lower part), S. schlumbergeri (agglutinated), Pullenia bulloides, C. tertis, E. pygmeus, N. affine, C. lobatulus and Florilus boueanus (uppermost sample, Fig. A1).

Remarks: According to King (1989), in the North Sea area, M. pseudotepida, C. limbatosuturalis and T. truncata are known from the uppermost Upper Miocene to the lowermost Upper Pliocene and F. boueanus is described from the Upper Oligocene to the Lower Pliocene. G. subglobosa is recorded from the Oligocene to the Lower Pliocene in the North Sea (Eidvin & Rundberg 2001 and Eidvin & Rundberg this volume).

GLOBOCASSIDULINA SUBGLOBOSA ASSEMBLAGE

Definition: The top and base of the assemblage is taken at the highest/youngest and lowest/oldest common occurrence of G. sublobosa.

Depth range: 750-790 m.

Material: Four ditch cutting samples.

Age: Late Miocene (partly based on planktonic fossil evidence).

Lithostratigraphic units: Molo Formation.

Correlation: Probably Zone NSB 12c and 13a of King (1989) and probably G. subglobosa – Ehrenbergina  variabilis zone of Stratlab (1988).

Description: This assemblage contains a moderately rich benthic fauna of mainly calcareous foraminifera. G. subgolosa and S. bulloides are both common. Other characteristic species include Bolivina imporcata, Cibicides dutemplei, N. affine, C. lobatulus, C. teretis, P. bulloides, Eponides umbonatus, T. truncata (agglutinated) and E. pygmeus (Fig. A1).   

Remarks: B. imporcata is described from the Middle to Upper Miocene in the Netherlands (Doppert 1980). C. dutemplei is known from the Upper Oligocene to the Lower Pliocene in the same area (Doppert 1980) and from the Upper Oligocene to the Upper Miocene on the Norwegian continental shelf (Skarbø & Verdenius 1986). A few specimens of Turrilina alsatica, which are reworked from Oligocene deposits, are recorded in some samples.

UNDEFINED INTERVAL

Depth range: 790-810 m.

Material: Two ditch cutting samples.

Age: Early Miocene (based on planktonic fossil evidence).

Lithostratigraphic unit: Brygge Formation.

Desciption: This interval contains a sparse benthic fauna of mainly calcareous foraminifera including N. affine, C. lobatulus, C. teretis, P. bulloides, E. umbonatus, G. subglobosa and S. bulloides (Fig. A1). However, all or most of these forms are probably caved. 

ROTALIATINA BULIMOIDES ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of R. bulimoides. The base of the assemblage is undefined.

Depth range: 810-860 m (lowermost investigated sample).

Material: Six ditch cutting samples.

Age: Early Oligocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Subzone NSB 7b of King (1989), Rotaliatina bulliomoides zone of Stratlab (1988) and probably Zone NSR 7A and lower part of Zone NSR 7B of Gradstein & Bäckström (1996).

Description: This unit contains a sparse benthic fauna of mainly calcareous foraminifera. Characteristic taxa include R. buliomoides, T. alsatica, Gyroidina soldanii girardana, Gyroidina soldanii mamillata (upper part), Alabamina scitula, P. bulloides, G. sublobosa, Frondicularia budensis, Dorothia seigliei (agglutinated, upper part, Fig. A1).

Remarks: G. soldanii mamilliata and R. bulimoides are known from the Lower Oligocene to the lowermost Upper Oligocene in the North Sea area according to King (1989). According to Gradstein & Bäckström (1996) are these species known from Eocene to Lower Oligocene deposits in the same area. They have also recorded R. bulimoides from such sediments in the Haltenbanken area. T. alsatica and G. soldanii girardana are known from the Lower Oligocene to the lowermost Lower Miocene succession in the North Sea (King 1989). According to Gradstein & Bäckström (1996) are T. alsatica recorded from Lower Oligocene to lowermost Upper Oligocene sediments in the North Sea and the Haltenbanken area. They describe G. soldanii girardana from the Upper Eocene to the lowermost Lower Miocene in the North Sea area.

A. scitula is recorded from Lower Oligocene to Lower Miocene sediments in the North Sea and the Haltenbanken area (Gradstein & Bäckström 1996). D. seigliei is recorded from Eocene to Lower Oligocene deposits in the North Sea and from Upper Palaeocene to Upper Eocene deposits in the Haltenbanken area (Gradstein & Bäckström 1996). F. budensis is known from the Lower Oligocene in the North Sea (King 1989).

Planktonic fossil assemblages

TURBOROTALIA QUINQUELOBA ASSEMBLAGE

Definition: The top of the assemblage extends to the uppermost investigated sample (620 m). The base is marked by the highest/youngest occurrence of Globigerina bulloides.

Depth range: 620-630 m.

Material: One ditch cutting sample.

Age: Late Pliocene.

Lithostratigraphic unit: Naust Formation.

Correlation: Probably Neogloboquadrina atlantica (sinistral) Zone of Weaver & Clement (1986) and Spiegler & Jansen (1989).

Description: Just a few specimens of T. quinqueloba are recorded in the sole sample in this interval (Fig. A1).

Remarks: T. quinqueloba is known from deposits from almost the entire Neogene on the Norwegian continental shelf (T. Eidvin, personal observation).

GLOBIGERINA BULLOIDES ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of G. bulloides. The base is marked by the highest/youngest occurrence of Neogloboquadrina atlantica (sinistral).

Depth range: 630-640 m.

Material: One ditch cutting sample.

Age: Late Pliocene.

Lithostratigraphic unit: Naust Formation.

Correlation: Globigerina bulloides Zone of Weaver & Clement (1986).

Description: Just a few specimens of G. bulloides are recorded in the sole sample which constitutes this interval (Fig. A1).

Remarks: Weaver & Clement (1986) describe a G. bulloides Zone from the North Atlantic (DSDP Leg 94) in Late Pliocene sediments as young as 2.2 Ma. On the Vøring Plateau G. bulloides is common in Late Miocene to Late Pliocene deposits older than 2.4 Ma (Spiegler & Jansen, 1989). G. bulloides is also common in the warmest interglacials of the last 0.5 Ma in the North Atlantic (Kellogg 1977).

NEOGLOBOQUADRINA ATLANTICA (SINISTRAL) ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of N. atlantica (sinistral). The base is marked by the highest/youngest occurrence of Bolboforma metzmacheri.

Depth range: 640-750 m

Material: Eleven ditch cutting samples.

Age: Early to Late Pliocene.

Lithostratigraphic units: Molo and Naust formations.

Correlation: N. atlantica (sinistral) Zone of Weaver & Clement (1986) and Spiegler & Jansen (1989).

Description: This unit is characterized by a moderately rich (lower part) to sparse (upper part) fauna of planktonic foraminifera. G. bulloides and N. atlantica (sinistral) occur most frequently. T. quinqueloba is also recorded in most parts of the unit. A few specimens of Neogloboquadrina pachyderma (dextral), Neogloboquadrina pachyderma (sinistral), Globigerinita glutinata and Neogloboquadrina atlantica (dextral) is also recorded in some samples (Fig. A1).

Remarks: N. atlantica (sinistral) is known from the North Atlantic and on the Vøring Plateau in Late Miocene to Late Pliocene sediments. The last appearance datum (LAD) of this species is in both areas approximately 2.4 Ma (Weaver & Clement 1986, Spiegler & Jansen 1989). On the Vøring Plateau there is a marked dominance of this species together with G. bulloides in Pliocene deposits older than this (Spiegler and Jansen 1989).

BOLBOFORMA METZMACHERI ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of B. metzmacheri. The base is marked by the highest/youngest occurrence of Diatom sp. 4 (King 1983).

Depth range: 750-790 m.

Material: Four ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Molo Formation.

Correlation: Bolboforma metzmacheri Zone of Spiegler & Müller (1992) and Müller & Spiegler (1993), Bolboforma metzmacheri zone of Stratlab (1988), Zone NSR 10 of Gradstein & Bäckström (1996) and Subzone NSP 14b of King (1983).

Description: The unit contains a moderately rich fossil assemblage of Bolboforma and foraminifera. Bolboforma subfragori and B. metzmacheri are the most common Bolboforma species. Bolboforma clodiusi and Bolboforma laevis (few) are also recorded in some samples. G. bulloides and N. atlantica (sinistral) are the most important foraminifera. Other taxa include N. atlantica (dextral), T. quinqueloba and Orbulina universa (Fig. A1).

Remarks: A B. fragori/B. subfragori Zone is known from deposits with an age of approximately 11.7-10.3 Ma from the North Atlantic and the Vøring Plateau. B. metzmacheri is described from sediments with an age of approximately 10.0-8.7 Ma in the same areas (Spiegler & Müller 1992 and Müller & Spiegler 1993). Consequently, in contrast to well 6407/9-5, B. metzmacheri occur in slightly younger sediments than B. subfragori in these areas. This can be due to the fact that the Bolboforma forms may have a slightly different range in the Draugen area on the inner continental shelf, than in the open ocean sites of the Norwegian Sea and the North Atlantic. It may also be due to the fact that the specimens of B. subfragori might be reworked. A number of pictures, taken of this species with electron microscope, reveal that most of the tests show indication of wear. It is also possible that sediment corresponding to the uppermost part of the B. metzmacheri Zone in the Norwegian Sea and North Atlantic is missing in well 6407/9-5.

DIATOM SP. 4 ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of Diatom sp. 4. The base of the assemblage is undefined biostratigraphically, but is taken at the gamma log break at approximately 810 m.

Depth range: 790-810 m.

Material: Two ditch cutting samples.

Age: Early Miocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Zone NSP 10 of King (1983).

Desciption: This interval contains a rich planktonic fossil assemblage of pyritized diatoms (including Diatom sp. 4) and radiolaria. A few caved Bolboforma and planktonic foraminifera are also recorded (Fig. A1).

Remarks: Diatom sp. 4 is described from Lower Miocene deposits in the North Sea (King 1983).

UNDEFINED INTERVAL

Depth range: 810-860 m.

Material: Six ditch cutting samples.

Age: Early Oligocene (based on bentic foraminiferal and palynological evidence).

Lithostratigraphic unit: Brygge Formation.

Description: Also this unit contain a rich planktonic fossil assemblage of pyritized diatoms and radiolaria (dominant), but no diatom index fossil is recorded (Fig. A1).

Well 6407/9-2

Benthic foraminiferal assemblages

ELPHIDIELLA HANNAI ASSEMBLAGE

Definition: The top of the assemblage extends to the uppermost investigated sample (760 m). The base is marked by the highest/youngest consistent occurrence of E. pygmeus.

Depth range: 760-810 m.

Material: Five ditch cutting samples.

Age: Late Pliocene.

Lithostratigraphic unit: Naust Formation.

Correlation: Zone NSB 15 of King (1989), Cibicides grossa zone of Stratlab (1988) and Zone NSR 12 B of Gradstein & Bäckström (1996).

Descrition: This unit contains a rich benthic fauna of calcareous foraminifera. E. excavatum occurs most frequently. Other important taxa include C. grossus, N. affine, E. albiumbilicatum, C. reniforme, B. marginata, C. teretis and C. lobatulus (Fig. A2).

Remarks: The occurrence of E. hannai and C. grossus show that this unit is of Late Pliocene age (Doppert 1980, King 1989).

EPONIDES PYGMEUS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest consistent occurrence of E. pygmeus. The bases is marked by the highest/youngest occurrence of M. pseudotepida.

Depth range: 810-830 m.

Material: Two ditch cutting samples.

Age: Early Pliocene.

Lithostratigraphic unit: Molo Formation.

Correlation: Probably Cibicides telegdi – Eponides pygmeus – Neogloboquadrina atlantica (dextral) zone of Eidvin et al. (1998a) and probably lower part of Melonis – Trifarinaz zone of Stratlab (1988).

Description: This assemblage contains a rich benthic fauna of mainly calcareous foraminifera. E. pygmeus, N. affine and C. teretis are all common. Other recorded species include C. lobatulus, P. bulloides, S. schlumbergeri (agglutinated), G. subglobosa and L. lammersi. One specimen of E. pygmeus is recorded in the lowermost sample (Fig. A2).

Remarks: This unit is correlated with the E. pygmeus assemblage in well 6407/9-5. Since taxa no older than earliest Late Miocene are recorded in the immediately underlying assemblage, this assemblage is most likely of Early Pliocene age.

MONSPELIENSINA PSEUDOTEPIDA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of M. pseudotepida. The base of the unit is undefined biostratigraphically, but is taken at the sonic log break at approximately 860 m.

Depth range: 830-860 m

Material: Three ditch cutting samples.

Age: Early Pliocene.

Lithostratigraphic unit: Molo Formation.

Collelation: Subzone NSB 14a of King (1989), Zone NSR 12A of Gradstein & Bäckström (1996).

Description: This unit contains a moderately rich (upper part) to sparse (lower part) benthonic fauna of calcareous foraminifera. N. affine is common in upper part of the unit. Other recorded taxa include M. pseudotepida, G. subglobosa, C. teretis and E. pygmeus (Fig. A2).

Remarks: M. pseudotepida is known from the uppermost Upper Miocene to the lowermost Upper Pliocene in the North Sea area (King 1989). This unit is correlated with the M. pseudotepida assemblage in well 6407/9-5.

UNDEFINED INTERVAL

Depth range: 860-890 m.

Material: Three ditch cutting samples.

Age: Early Oligocene (based on palynological evidence and seismic correlation).

Lithostratigraphic unit: Brygge Formation.

Description: This interval is nearly barren of benthic foraminifera and only just a long range agglutinated form (Bathysiphon sp.) is recorded (Fig. A2).

SPIROSIGMOILINELLA COMPRESSA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of S. compressa. The base is marked by the highest/youngest occurrence of Alabamina scitula.

Depth range: 890-900 m.

Material: One ditch cutting samples.

Age: Early Oligocene (partly based on palynological evidence).

Lithostratigraphic unit: Brygge Formation.

Correlation: Probably Zone NSR 7A or 7B of Gradstein & Bäckström (1996) and probably Zone NSA 7 or 8 of King (1989).

Description: Just a few specimens of S. compressa (agglutinated) are recorded in the sole sample of this unit (Fig. A2).

Remarks: Spirosigmoilinella sp. A (synonymous with S. compressa) is known from the Lower Oligocene to Lower Miocene succession in the North Sea (King, 1989). According to Gradstein & Bäckström (1996) is this species known from the Middle Eocene to the Upper Oligocene in the North Sea and from the Middle Eocene to the Lower Oligocene in the Haltenbanken area.

ALABAMINA SCITULA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of A. scitula. The base of the assemblage is undefined.

Depth range: 900 m (one sample only).

Material: One ditch cutting sample.

Age: Early Oligocene (partly based on palynological evidence).

Lithostratigraphic unit: Brygge Formation.

Correlation: Probably Zone NSR 7A or 7B of Gradstein & Bäckström (1996).

Description: Just a few specimens of A. scitula are recorded in the sole sample of this unit (Fig. A2).

Remarks: According to Gradstein & Bäckström (1996) is A. scitula known from the Lower Oligocene to Lower Miocene in the North Sea and from the Lower Oligocene to the basal Middle Miocene in the Haltenbanken area.      

Planktonic fossil assemblages

UNDEFINED INTERVAL

Depth range: 760-780 m.

Material: Two ditch cutting samples.

Age: Late Pliocene (based on benthic foraminiferal evidence).

Lithostratigraphic unit: Naust Formation.

Description: This unit is barren of planktonic foraminifera.

NEOGLOBOQUADRINA ATLANTICA (SINISTRAL) ASSEMBLAGE

Definition: The top and base of the assemblage is taken at the highest/youngest and lowest/oldest occurrence of N. atlantica (sinistral).

Depth range: 780-830 m.

Material: Six ditch cutting samples.

Age: Early to Late Pliocene.

Lithostratigraphic units: Molo Formation and Naust Formation.

Correlation: N. atlantica (sinistral) Zone of Weaver & Clement (1986) and Spiegler & Jansen (1989).

Description: This Unit is characterized by a sparse (upper part) to moderately rich (lower part) fauna of planktonic foraminifera. G. bulloides and N. atlantica (sinistral) occur most frequently. Other recorded taxa include T. quinqueloba, G. glutinata, N. pachyderma (dextral) and N. atlantica (dextral, Fig. A2).

Remarks: N. atlantica (sinistral) is known from the North Atlantic and on the Vøring Plateau in Late Miocene to Late Pliocene sediments. The LAD of this species is in both areas, approximately 2.4 Ma (Weaver & Clement 1986, Spiegler & Jansen 1989). N. atlantica (dextral) is known to occur in the uppermost Upper Pliocene and in the Upper Miocene on the Vøring Plateau (Spiegler & Jansen 1992, Müller & Spiegler 1993). Consequently, the sole specimen recorded here is either caved or reworked from Upper Miocene deposits.

UNDEFINED INTERVAL

Depth range: 830-860 m

Material: Three ditch cutting samples.

Age: Early Pliocene (based on palynological evidence).

Lithostratigraphic unit: Molo Formation.

Description: This interval is barren of planktonic foraminifera.

DIATOM SP. ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest consistent occurrence of pyritized diatoms. The base is marked by the highest/youngest occurrence of Diatom sp. 3 (King, 1983).

Depth range: 860-870 m.

Material: One ditch cutting sample.

Age: Early Oligocene (based on palynological evidence).

Lithostratigraphic unit: Brygge Formation.

Correlation: Subzone NSP 9c of King (1989).

Description: This interval contains a moderately rich planktonic fossil assemblage of pyritized diatoms and radiolaria (Fig. A2).

Remarks: No planktonic index fossils are recorded.

DIATOM SP. 3 ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of Diatom sp. 3. The base of the assemblage is undefined.

Depth range: 870-900 m.

Material: Four ditch cutting samples.

Age: Early Oligocene (partly based on palynological evidence).

Lithostratigraphic unit: Brygge Formation.

Correlation: Subzone NSP 9c of King (1989).

Description: This unit contains a moderately rich planktonic fossil assemblage of pyritized diatoms and radiolaria. Diatom sp. 3 is recorded in the upper part of the unit (Fig. A2).

Remarks: Diatom sp. 3 is known from the upper part of Lower Oligocene to the lower part of Lower Miocene in the North Sea area (King 1989).

Well 6407/9-1

Benthic foraminiferal assemblages

ELPHIDIELLA HANNAI ASSEMBLAGE

Definition: The top of the assemblage extends to the uppermost investigated sample (650 m). The base is marked by the highest/youngest occurrence of S. bulloides and the highest consistent occurrence of E. pygmeus.

Depth range: 650-760 m.

Material: Eleven ditch cutting samples.

Age: Early Pliocene.

Lithostratigraphic unit: Naust Formation.

Correlation: Zone NSB 15 of King (1989), Cibicides grossa zone of Stratlab (1988) and Zone NSR 12 B of Gradstein & Bäckström (1996).

Descrition: This assemblage contains a moderately rich fauna of mainly calcareous foraminifera. E. excavatum and C. lobatulus occur most frequently. Other characteristic taxa include E. hannai, C. grossus, N. affine, E. albiumbilicatum and B. marginata (Fig. A3).

Remarks: The occurrence of E. hannai and C. grossus indicates a Late Pliocene age (Doppert 1980, King 1989).

EPONIDES PYGMEUS – SPHAEROIDINA BULLOIDES ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest E. pygmeus. The base is marked by the lowest/oldest consistent occurrence of E. pygmeus and S. bulloides.

Depth range: 760-790 m.

Material: Four ditch cutting samples.

Age: Early Pliocene.

Lithostratigraphic unit: Molo Formation.

Correlation: Probably Cibicides telegdi – Eponides pygmeus – Neogloboquadrina atlantica (dextral) zone of Eidvin et al. (1998a) and probably lower part of Melonis – Trifarina zone of Stratlab (1988).

Description: This unit contains a rich fauna of mainly calcareous foraminifera. N. affine and C. teretis occur most frequently. Other characteristic taxa include E. pygmeus, S. bulloides, A. fluens, L. lammersi and P. bulloides (Fig. A3).

Remarks: This unit is correlated with the E. pygmeus assemblages in well 6407/9-5 and 6407/9-1 and is most likely of Early Pliocene age.

UNDEFINED INTERVAL

Depth range: 790-850 m.

Material: Four ditch cutting samples.

Age: Early Oligocene (lower part) and Late Miocene to Early Pliocene (upper part, based on palynological evidence and log correlation).

Lithostratigraphic unit: Brygge Formation and Molo Formation.

Description: This interval is nearly barren of benthic foraminifera and only just a long range agglutinated form (Bathysiphon sp.) is recorded (Fig. A3).

GYROIDINA SOLDANII GIRARDANA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of G. soldanii girardana. The base is marked by the highest/youngest occurrence of T. alsatica.

Depth range: 850-880 m.

Material: Three ditch cutting samples.

Age: Early Oligocene (partly based on palynological evidence).

Lithostratigraphic unit: Brygge Formation.

Correlation: Probably Subzone NSB 7b of King (1989) and probably Zone NSR 7B of Gradstein & Bäckström (1996).

Description: This interval contains a sparse benthic fauna of mainly calcareous foraminifera. Characteristic taxa include G. soldanii girardana, E. pygmeus, A. scitula, Bathysiphon sp. (agglutinated) and Trifarina gracilis (Fig. A3).

Remarks: G. soldanii girardana is known from the Lower Oligocene to the lowermost Lower Miocene succession in the North Sea according to (King, 1989), and from the Upper Eocene to the lowermost Lower Miocene in the same area according to Gradstein & Bäckström (1996). T. gracilis is described from Lower Oligocene to Lower Miocene deposits on the Norwegian continental shelf according to Skarbø & Verdenius (1986).

TURRILINA ALSATICA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of T. alsatica. The base is marked by the highest/youngest occurrence of G. soldanii mamillata.

Depth range: 880-910 m

Material: Three ditch cutting samples.

Age: Early Oligocene (partly based on Sr. analyses).

Lithostratigraphic unit: Brygge Formation.

Correlation: Probably Subzone NSB 7b of King (1989) and probably Zone NSR 7B of Gradstein & Bäckström (1996).

Description: This unit contains a moderately rich benthic fauna of mainly calcareous foraminifera. T. alsatica and A. scitula occur most frequently. Other characteristic species include G. subglobosa, P. bulloides, E. pygmeus, C. telegdi, G. soldanii girardana, Stilostomella hirsuta, Stilostomella spinescens and Guttulina frankei (Fig. A3).

Remarks: According to Gradstein & Bäckström (1996) is A. scitula known from the Lower Oligocene to Lower Miocene in the North Sea and from the Lower Oligocene to the basal Middle Miocene in the Haltenbanken area. T. alsatica are described from the Lower Oligocene to lowermost Lower Miocene in the North Sea area according to King (1989), and from Lower Oligocene to lowermost Upper Oligocene sediments in the North Sea and Haltenbanken area according to Gradstein & Bäckström (1996). S. hirsuta, S. spinescens and G. frankei are described from the upper part of Lower Oligocene in Denmark (Ulleberg 1974).

GYROIDINA SOLDANII MAMILLATA ASSEMBLAGE

Definition: The top of the assemblage is taken the highest/youngest occurrence of G. soldanii mamillata. The base is marked by the highest/youngest occurrence of R. bulimoides.

Depth range: 910-920 m.

Material: One ditch cutting sample.

Age: Early Oligocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Subzone NSB 7b of King (1989) and Zone NSR 7B of Gradstein & Bäckström (1996).

Description: This assemblage contains a moderately rich fauna of mainly calcareous foraminifera. T. alsatica occur most frequently. Other recorded taxa include G. soldanii mamillata, A. scitula and C. telegdi (Fig. A3).

Remarks: G. soldanii mamilliata is known from the Lower Oligocene to the lowermost Upper Oligocene in the North Sea area according to King (1989). According to Gradstein & Bäckström (1996) is this species known from Eocene to Lower Oligocene deposits in the same area.

ROTALIATINA BULIMOIDES ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of R. bulimoides. The base of the assemblage is undefined.

Depth range: 920-990 m (lowermost investigated sample).

Material: Five ditch cutting samples.

Age: Early Oligocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Subzone NSB 7b of King (1989), Rotaliatina bulliomoides zone of Stratlab (1988) and probably Zone NSR 7A and lower part of Zone NSR 7B of Gradstein & Bäckström (1996).

Description: This assemblage contains a moderately rich benthic fauna of calcareous and agglutinated foraminifera. Characteristic calcareous taxa include R. bulimoides, T. alsatica, A. scitula and S. spinescens and agglutinated forms include Bathysiphon eocenicus, Bathysiphon spp., Adercotryma agterbergi and Glomospira sp. (Fig. A3).

Remarks: R. bulimoides is recorded from the Lower Oligocene to the lowermost Upper Oligocene in the North Sea according to King (1989) and from the Eocene to the Lower Oligocene in the North Sea and Haltenbanken area according to Gradstein & Bäckström (1996). A. agterbergi is known from Eocene to Lower Oligocene deposits in the North Sea and Haltenbanken area according to Gradstein & Bäckström (1996).

Planktonic fossil assemblages

UNDEFINED INTERVAL

Depth range: 650-670 m.

Material: Two ditch cutting samples.

Age: Late Pliocene (based on benthic foraminiferal evidence).

Lithostratigraphic unit: Naust Formation.

Description: This unit is barren of planktonic foraminifera.

GLOBIGERINA BULLOIDES ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of G. bulloides. The base is marked by the highest/youngest occurrence of N. atlantica (sinistral).

Depth range: 670-780 m.

Material: Eleven ditch cutting samples.

Age: Early to Late Pliocene.

Lithostratigraphic unit: Molo Formation and Naust Formation.

Correlation: G. bulloides Zone of Weaver & Clement (1986) and probably N. atlantica (sinistral) Zone of Weaver & Clement (1986) and Spiegler & Jansen (1989).

Description: Planktonic foraminifera are quite sparse in this unit. G. bulloides is recorded throughout. N. pachyderma (sinistral) is recorded in one sample in the middle part of the unit and a few specimens of T. quinqueloba and N. atlantica (dextral, one specimen) are recorded in one sample in the lower part of the unit (Fig. A3).

Remarks: A G. bulloides Zone is described from the North Atlantic (DSDP Leg 94) in Pliocene sediments as young as 2.2 Ma (Weaver & Clement 1986). On the Vøring Plateau G. bulloides is common in Pliocene deposits older than 2.4 Ma (Spiegler & Jansen 1989). G. bulloides is also common in the warmest interglacials of the last 0.5 Ma in the North Atlantic (Kellogg 1977). N. atlantica (dextral) is known to occur in the uppermost Upper Pliocene and in the Upper Miocene on the Vøring Plateau (Spiegler & Jansen 1992, Müller & Spiegler 1993). Consequently, the sole specimen recorded here is either caved or reworked from Upper Miocene deposits.

NEOGLOBOQUADRINA ATLANTICA (SINISTRAL) ASSEMBLAGE

Definition: The top and base of the assemblage is taken at the highest/youngest and lowest/oldest occurrence of N. atlantica (sinistral).

Depth range: 780-790 m.

Material: Two ditch cutting samples.

Age: Early Pliocene.

Lithostratigraphic unit: Molo Formation.

Correlation: N. atlantica (sinistral) Zone of Weaver & Clement (1986) and Spiegler & Jansen (1989).

Desription: This interval is characterized by a sparse fauna of plaktonic foraminifera. Recorded taxa include G. bulloides, N. atlantica (sinistral), T. quinqueloba and N. atlantica (dextral, one specimen, Fig. A3).

Remarks: N. atlantica (sinistral) is known from the North Atlantic and on the Vøring Plateau in Late Miocene to Late Pliocene sediments. The sole specimen of N. atlantica (dextral) is either caved or reworked.

UNDEFINED INTERVAL

Depth range: 790-990 m.

Material: 15 ditch cutting samples.

Age: Early Oligocene in the lower part and Late Miocene to Early Pliocene in the upper part (based on benthic foraminiferal and palynological evidence and Sr. analyses).

Lithostratigraphic unit: Brygge Formation and Molo Formation.

Description: This interval contains a moderately rich planktonic fossil assemblage dominated by pyritized diatoms and radiolaria (Fig. A3), but no radiolaria or diatom index fossils are recorded. A few planktonic foraminifera are recorded in some samples including G. bulloides, N. pachyderma (dextral) and Globigerina praebulloides. The first two species are probably caved.

Remarks: G. praebulloides is known from Oligocene to lower Upper Miocene deposits in the North Atlantic (Poore 1979) and from Oligocene to lower Middle Miocene deposits in the North Sea (Gradstein & Bäckström 1996). Poore (1979) suggest that a clear separation of G. praebulloides and G. bulloides may be difficult in extra-tropical regions.

Dinoflagellate cyst zones

The investigated Upper Pliocene succession contains few in situ dinoflagellate cysts, but common to abundant reworked older Cenozoic and Mesozoic specimens. More rich and diverse marine microfloras are encountered in the Lower Pliocene strata, and the abundance and diversity increases further downward into Upper and Lower Miocene deposits. A relative rich and diverse dinoflagellate cyst assemblage is also recovered from the Lower Oligocene sequence in the wells. The poor recovery of in situ dinoflagellate cysts in the Upper Pliocene succession provide no mean for a palynostratigraphic zonation of these strata. The recovered marine micro flora allow, however, a good biostratigraphic breakdown of the Lower Pliocene to Lower Oligocene interval in the Draugen Field wells 6407/9-5, -/9-2 and -/9-1.

Well 6407/9-5

UNDEFINED INTERVAL

Depth range: 620-670 m.

Material: Seven ditch cutting samples.

Age: Late Pliocene (based on benthic and planktonic foraminiferal evidence).

Lithostratigraphic unit: Naust Formation.

Description: This interval contains only few in situ dinoflagellate cysts, including Brigantedinium spp., Bitectatodinium tepikiense, Operculodinium centrocarpum, Impagidinium spp. and Spiniferites spp. (Fig. A4). The unit contains reworked Paleogene, Cretaceous and Jurassic dinoflagellate cysts.

Remarks: There are no age-diagnostic dinoflagellate cyst species and the age of this interval is determined by the presence of the Elphidella hannei foraminiferal assemblage.

UNDEFINED INTERVAL

Depth range: 670-690 m.

Material: Three ditch cutting samples.

Age: Early Pliocene (partly based on benthic and planktonic foraminiferal evidence).

Lithostratigraphic unit: Molo Formation.

Description: This interval contains only few in situ dinoflagellate cysts (with typically less than 5 species present), but common to abundant reworked older Cenozoic and Mesozoic specimens. The in situ marine microfloras include Brigantedinium spp., Bitectatodinium tepikiense, Operculodinium centrocarpum, Operculodinium israelianum, Impagidinium spp., Tectatodinium spp. and Spiniferites spp. (Fig. A4).

Remarks: There are no age-diagnostic dinoflagellate cyst species and the age of this interval is determined by the presence of the Eponides pygmes foraminiferal assemblage. The recovery of the thermophilic dinoflagellate species Operculodinium israelianum at 680-690 m may, however, be taken as an indicator of somewhat warmer and thus Early–Mid Pliocene climatic conditions. This species is also consistently present in the underlying Lower Pliocene strata.

RETICULATOSPHAERA ACTINOCORONATA ZONE

Definition: The body of strata between the highest/youngest occurrence of Reticulatosphaera actinocoronata and the highest/youngest occurrence of Achomosphaera sp. 1.

Depth range: 690-750 m.

Material: Seven ditch cutting samples.

Age: Early Pliocene.

Lithostratigraphic unit: Molo Formation.

Description: This interval contains moderately rich and diverse assemblages of in situ dinoflagellate cysts. Reworked Paleogene, Creetaceous and Jurassic dinoflagellate cysts are relatively common. Characteristic in situ species include Amiculosphaera umbracula, Barssidinium graminosum, Barssidinium pliocenicum, Impagidinium spp., Tectatodinium spp., Operculodinium isralianum, Lingulodinium machaerophorum, Reticulatosphaera actinocoronata, Selenopemphix spp. and Trinovantedinium variabile (Fig. A4).

Remarks: Poulsen et al. (1996) used the last occurrence datum of Reticulatosphaera actinocoronata to define the upper boundary of their Pli1 Zone in ODP Holes 908 and 909. This zone was dated as Zanclean, i.e. time equivalent to calcareous nannoplankton zones NN12-14.

ACHOMOSPHAERA SP. 1 ASSEMBLAGE ZONE

Definition: The body of strata defined by the presence of Achomosphaera sp. 1.

Depth range: 750-790 m.

Material: Four ditch cutting samples.

Age: Late Miocene-Early Pliocene (partly based on benthic foraminiferal and planktonic fossil evidence).

Lithostratigaphic unit: Molo Formation.

Description: The ditch cutting sample from this zone contain moderate diversity of dinoflagellate cysts, including common to abundant Achomosphaera sp. 1, together with Amiculosphaera umbracula, Barssidinium graminosum, Barssidinium pliocenicum, Barssidinium evangelineae, Cyclopsiella vieta, Selenopemphix spp. and common Operculodinium israelianum (Fig. A4).

Remarks: Achomosphaera sp. 1 has previously been consistently recorded in Upper Miocene-Lower Pliocene strata at ODP Sites 907, 908 and 909 in the Norwegian-Greenland Sea (Poulsen et al. 1996).

CORDOSPHAERIDIUM CANTHARELLUM ZONE

Definition: The body of strata between the highest/youngest occurrence of Cordosphaeridium cantharellum and the highest/youngest occurrence of Caligodinium amiculum (Smelror et al. in press).

Depth range: 790-810 m.

Material: Two ditch cutting samples.

Age: Mid Early Miocene.

Lithostratigaphic unit: Brygge Formation.

Description: The zone contains rather poor and low and diverse assemblage of in situ dinoflagellate cysts. The samples from this zone are otherwise obscured by reworked Paleogene and caved Neogene dinoflagellate cysts. The recovered in situ key species include Cordosphaeridium cantharellum, Palaeocystodinium spp. and Thalassiphora pelagica (Fig. A4).

Remarks: Powell (1992) calibrated the LAD of Cordosphaeridium cantharellum to the lower NN 4 Zone in the British Tertiary, while de Verteuil & Norris (1996) placed the LAD in the upper NN 2 in their study on the Miocene of the U.S. Atlantic Margin. Williams and Manum (1999) gave an age of 17.95 Ma for the LAD of C. cantharellum, which is in agreement with a calibration to the lower NN 4 Zone.

AREOLIGERA SEMICIRCULATA ZONE

Definition: The body of strata between the highest/youngest occurrence of Areoligera semicirculata and the highest/youngest occurrence of Svalbardella cooksoniae.

Depth range: 810-860 m.

Material: One ditch cutting sample.

Age: Early Oligocene (partly based on benthic foraminiferal evidence and Sr. analyses).

Lithostratigaphic unit: Brygge Formation.

Description: The zone contains a moderate rich and diverse marine microflora. Characteristic for this zone in well 6407/9-5 is the acme of Deflandrea phosphoritica, and the presence of Chiropteridium lobospinosum and Spiniferites sp. 1 which are restricted to this zone in the well (Fig. A4).

Remarks: According to Powell (1992) the LAD of A. semicirculata lays within the lower NP25 calcareous nannoplankton biozone in Britain and in the North Sea area. Manum et al. (1989) found that the LAD of this species (named Glaphyrocysta intricata in their publication) corresponded to the upper boundary of their Early/Late Oligocene Areosphaeridium? actinocoronatum in ODP Hole 643 in the Norwegian Sea. The LAD of this species also defines the upper boundary of the Oli4 Zone of Poulsen et al. (1996) as defined in ODP Hole 908 on the Hovgaard Ridge between Svalbard and NE Greenland. 

SVALBARDELLA COOKSONIAE ZONE

Definition: The body of strata between the highest/youngest occurrence of Svalbardella cooksoniae and the highest/youngest occurrence of Areosphaeridium dictyoplokus.

Depth range: 860 m.

Material: One ditch cutting sample.

Age: Early Oligocene.

Lithostratigaphic unit: Brygge Formation.

Description: The zone contains a fairly rich and diverse marine microflora, with Svalbardella cooksoniae, Deflandrea phosphoritica, Lentinia serrata and Homotrybilum oceanicum being characteristic species (Fig. A4).

Remarks: Manum et al. (1989) found that Svalbardella cooksonia was restricted to their Early Oligocene Chiropteridium lobospinosum Zone in ODP Hole 643 in the Norwegian Sea.

Well 6407/9-2

UNDEFINED INTERVAL

Depth range: 760-820 m.

Material: Six ditch cutting samples.

Age: Early to Late Pliocene (partly based on benthic and planktonic foraminiferal evidence).

Lithostratigraphic unit: Upper part of Molo Formation and Naust Formation.

Description: This interval contains only few in situ dinoflagellate cysts, but common to abundant reworked older Cenozoic and Mesozoic specimens. The in situ marine microfloras include Achomosphaera andalousiensis, Bitectatodinium tepikiense, Operculodinium centrocarpum, Filisphaera filifera spp., Lingulodinium machaerophorum and Spiniferites spp. (Fig. A5).

Remarks: The single record of Filisphaera filifera at 780 m suggests a correlation to the Upper Pliocene Filisphaera filifera Zone of Smelror et al. (in press.). Otherwise the age of this interval is determined by the presence of the Elphidella hannei foraminiferal assemblage.

ACHOMOSPHAERA SP. 1 ASSEMBLAGE ZONE

Definition: The body of strata defined by the presence of Achomosphaera sp. 1.

Depth range: 820-860 m.

Material: Four ditch cutting samples.

Age: Early Pliocene (partly based on benthic foraminiferal evidence).

Lithostratigaphic unit: Molo Formation.

Description: The samples from this zone contain moderate diversity of dinoflagellate cysts, including common to abundant Achomosphaera sp. 1, together with Amiculosphaera umbracula, Barssidinium graminosum, Cyclopsiella vieta, Impagidinium spp., Reticulatosphaera actinocoronata, Operculodinium janduchenei and common Operculodinium israelianum (Fig. A5). The zone also contains common reworked Early-Middle Miocene, Paleogene, Cretaceous and Jurassic dinoflagellate cysts.

Remarks: Achomosphaera sp. 1 has previously been consistently recorded in Upper Miocene-Lower Pliocene strata at ODP Sites 907, 908 and 909 in the Norwegian-Greenland Sea (Poulsen et al. 1996).

AREOLIGERA SEMICIRCULATA ZONE

Definition: The body of strata between the highest/youngest occurrence of Areoligera semicirculata and the highest/youngest occurrence of Svalbardella cooksoniae.

Depth range: 860-880 m.

Material: Two ditch cutting samples.

Age: Early Oligocene (partly based on log correlation).

Lithostratigaphic unit: Brygge Formation.

Description: The zone contains a moderate rich and diverse marine microflora. An acme of Deflandrea phosphoritica and Cordosphaeridium cantharellum is found in the lower part of the zone. Areoligera semicirculata is common throughout the zone (Fig. A5). The sample at 860 m contains reworked Early Cretaceous dinoflagellate cysts.

Remarks: See remarks given under the Areoligera semicirculata Zone in well 6407/9-5.

SVALBARDELLA COOKSONIAE ZONE

Definition: The body of strata between the highest/youngest occurrence of Svalbardella cooksoniae and the highest/youngest occurrence of Areosphaeridium dictyoplokus.

Depth range: 880-890 m.

Material: Two ditch cutting samples.

Age: Early Oligocene.

Lithostratigaphic unit: Brygge Formation.

Description: The zone contains a fairly rich and diverse marine microflora, with Svalbardella cooksoniae, Deflandrea phosphoritica and Glaphyrocysta semitecta (Fig. A5). The lowermost sample at 890 m also contains reworked Middle-Late Jurassic dinoflagellate cysts.

Remarks: Manum et al. (1989) found that Svalbardella cooksonia was restricted to their Early Oligocene Chiropteridium lobospinosum Zone in ODP Hole 643 in the Norwegian Sea.

Well 6407/9-1

UNDEFINED INTERVAL

Depth range: 750-760 m.

Material: Two ditch cutting samples.

Age: Late Pliocene (based on benthic and planktonic foraminiferal evidence).

Lithostratigraphic unit: Naust Formation.

Description: This interval contains only few in situ dinoflagellate cysts, but common to abundant reworked older Cenozoic and Mesozoic specimens. The in situ marine microfloras include Bitectatodinium tepikiense, Operculodinium centrocarpum, Lingulodinium machaerophorum and Spiniferites spp. (Fig. A6).

Remarks: There are no age-diagnostic dinoflagellate cyst species and the age of this interval is determined by the presence of the Elphidella hannei foraminiferal assemblage.

RETICULATOSPHAERA ACTINOCORONATA ZONE

Definition: The body of strata between the highest/youngest occurrence of Reticulatosphaera actinocoronata and the highest/youngest occurrence of Achomosphaera sp. 1.

Depth range: 760-790 m.

Material: Seven ditch cutting samples.

Age: Early Pliocene

Lithostratigraphic unit: Molo Formation.

Description: This interval contains moderately rich and diverse assemblages of in situ dinoflagellate cysts. Characteristic species include Amiculosphaera umbracula, Barssidinium graminosum, Operculodinium israelianum,Reticulatosphaera actinocoronata, and common Impagidinium sp. A (Fig. A6). Reworked Paleogene, Cretaceous and Jurassic dinoflagellate cysts are also present.

Remarks: The foraminifera suggest that the sample at 760 m belongs to the Upper Pliocene interval. The presence of Reticulosphaera actinocoronata, together with the thermophilic species Operculodinium israelianum, suggests, however, an Early Pliocene age for this sample. Alternatively these taxa could be reworked.

ACHOMOSPHAERA SP. 1 ASSEMBLAGE ZONE

Definition: The body of strata defined by the presence of Achomosphaera sp. 1.

Depth range: 790-840 m.

Material: Three ditch cutting samples.

Age: Early Oligocene (lowermost part, based on log correlation) and Late Miocene-Early Pliocene.

Lithostratigaphic unit: Upper part of Brygge Formation and Molo Formation.

Description: The ditch cutting sample from this zone contains moderate diversity of dinoflagellate cysts, including common Achomosphaera sp. 1, together with Barssidinium graminosum (Fig. A6). The zone also includes reworked Early-Middle Miocene, Paleogene and Early Cretaceous dinoflagellate cysts.

Remarks: Achomosphaera sp. 1 has previously been consistently recorded in Lower Pliocene-Upper Miocene strata at ODP Sites 907, 908 and 909 in the Norwegian-Greenland Sea (Poulsen et al. 1996). The occurrence of Achomosphaera sp. 1 in Lower Oligocene deposits is probably caved.

AREOLIGERA SEMICIRCULATA ZONE

Definition: The body of strata between the highest/youngest occurrence of Areoligera semicirculata and the highest/youngest occurrence of Svalbardella cooksoniae.

Depth range: 840-850 m.

Material: Two ditch cutting samples.

Age: Early-Late Oligocene (partly based on benthic foraminiferal evidence).

Lithostratigaphic unit: Brygge Formation.

Description: The zone contains a moderate rich and diverse marine microflora. Characteristic for this zone in well 6407/9-1 is the acme of Deflandrea phosphoritica and Systematophora placacantha, combined with common Areoligera semicirculata. Other characteristic species include Dapsilidinium simplex, common Wetzeliella articulata, Rhombodinium draco and Samlandia chlamydophora (Fig. A6).

Remarks: See remarks given under the Areoligera semicirculata Zone in well 6407/9-5.

Strontium isotope stratigraphy

Four intervals from well 6407/9-5 and two intervals from well 6407/9-1 were analysed for strontium isotopes. 16 to 60 tests of calcareous foraminifera were used for the analyses. A problem with obtaining strontium isotope ages from foraminifera is the common presence of impurities in the foraminiferal chambers. Careful cleaning is sometimes not able to remove these, and this can influence the strontium rates and consequently the datings (Eidvin et al. 1999). In this work, we have used the look-up table presented by Howard and McArthur (1997: version 3:10/99) for numerical age assignments, and all results are corrected to NIST (National Institute of Standards and Technology) 987 = 0.710248.

In well 6407/9-5 presumed in situ tests of G. subglobosa, S. bulloides and M. pseudotepida were picked from the interval 710-730 m. The sample gave a corrected ⁸⁷Sr/⁸⁶Sr-ratio of 0.709010. On the seawater Sr isotope curve of Howarth & McArthur (1997) this ⁸⁷Sr/⁸⁶Sr-ratio corresponds to an age of approximately 5.7 Ma. Tests of G. subglobosa and S. bulloides from the sample at 740 m gave a corrected ⁸⁷Sr/⁸⁶Sr-ratio of 0.709006 corresponding to an age of approximately 5.8 Ma. Tests of the same foraminiferal species from the interval 750-760 m and 770-780 m gave corrected ⁸⁷Sr/⁸⁶Sr-ratios of 0.709030 and 0.709003 corresponding to ages of approximately 5.8 and 5.2 Ma respectively. Tests of G. soldanii girardana, T. alsatica, F. budensis, Bolivina cf. antique and A. scitula from the interval 810-830 m gave a corrected ⁸⁷Sr/⁸⁶Sr-ratio of 0.707972 corresponding to an age of approximately 30.3 Ma (Table 1, Fig. A1).

In well 6407/9-1 tests of S. bulloides, E. pygmeus, Ceratobulimina sp. and G. subglobosa from the sample at 790 m gave a corrected ⁸⁷Sr/⁸⁶Sr-ratio of 0.708981 corresponding to an age of approximately 6.0 Ma. Tests of Bolivina cf. antique, T. alsatica, A. scitula and G. soldanii girardana from the sample at 900 m gave a corrected ⁸⁷Sr/⁸⁶Sr-ratio of 0.707876 corresponding to an age of approximately 32.4 Ma (Table 1, Fig. A3).

Lithology

Upper Pliocene (Naust Formation)

The ditch cutting samples from this unit contain a clay-rich diamicton witch is rich in sand, silt and pebbles. The pebbles are mostly of crystalline lithology, but some of sedimentary rocks are also recorded. All these pebbles are interpreted as ice-rafted. Glacio-marine sediments of the Vøring Plateau have been the subject of studies by Jansen & Sjøholm (1991) and Fronval & Jansen (1996). These studies demonstrated the presence of ice-rafted material in sediments as old as 12.6 Ma. The frequency of ice-rafted material increases during the period between 7.2 and 6.0 Ma, but remains relatively low between 6.0 Ma and 2.75 Ma. A marked increase in the supply of such material after about 2.75 Ma reflects the expansion of the northern European glaciers. The maximum age of the Naust Formation in the studied wells is therefore assigned to be 2.75 Ma.

Upper Miocene and Lower Pliocene (Molo Formation)    

The ditch cutting samples from these units contain mainly glauconitic sand, silt and clay. Some pebbles are also recorded, but these are probably caved.

Oligocene and Lower Miocene (Brygge Formation)

These sections contain mostly fine grained material. Mostly clay is found on the samples, but small proportions of silt and glauconitic sand are also recorded. The latter may be caved from the immediately overlying Molo Formation.

Stratigraphical conclusion for well 6407/9-5, 6407/9-2 and 6407/9-1

Upper Pliocene (Naust Formation)

The lower part of the Upper Pliocene is investigated in all wells and corresponds to the benthic foraminiferal E. hannai assemblage (Fig. 10). In well 6407/9-5 these deposits correspond to planktonic foraminiferal T. quinqueloba, G. bulloides and N. atlantica (sinistral, upper part) assemblages. In well 6407/9-2 the Upper Pliocene corresponds to the planktonic foraminiferal N. atlantica (sinistral) assemblage (upper part) and in well 6407/9-1 to the planktonic foraminiferal G. bulloides assemblage (upper part). A large proportion of ice-rafted detritus in the deposits indicate that the sediments were deposited after the marked increase in the supply of ice-rafted detritus to the Norwegian Sea, which started at about 2.75 Ma (Fronval & Jansen 1996, Fig. 10).

Lower Pliocene (Molo Formation)

The Lower Pliocene is observed in all wells (Fig. 10). In well 6407/9-5 these deposits correspond to the benthic foraminiferal E. pygmeus and M. pseudotepida assemblages, the planktonic foraminiferal N. atlantica (sinistral) assemblage (lower part) and the dinoflagellate R. actinocronata Zone. In well 6407/9-2 the Lower Pliocene correspond to the benthic foraminiferal E. pygmeus and M. pseudotepida assemblages, the planktonic foraminiferal N. atlantica (sinistral) assemblage (lower part) and the dinoflagellate Achomosphaera sp. 1 Assemblage Zone. In well 6407/9-1 these deposits correspond to the benthic foraminiferal E. pygmeus – S. bulloides assemblage, the planktonic foraminiferal G. bulloides (lower part) and N. atlantica (sinistral) assemblages and the dinoflagellate R. actinocronata Zone. Two Sr. analyses in the lower part of the unit in well 6407/9-5 give the ages of approximately 5.7 and 5.8 Ma. This is slightly older than the Early Pliocene/Late Miocene boundary according to Berggren et al. (1995, approximately 5.3 Ma), but it is within the accuracy of the method (Eidvin et al. 1999).

Upper Miocene to Lower Pliocene (Molo Formation)

Sediments given a general Late Miocene to Early Pliocene age are only observed in well 6407/9-1 corresponding to the dinoflagellate Achomosphaera sp. 1 Assemblage Zone (Fig. 10). A Sr. analysis in the upper part of the unit gives an age of approximately 6.0 Ma (Fig. A3).

Upper Miocene (Molo Formation)

Upper Miocene deposits are only recorded in the well 6407/9-5 corresponding to the benthic foraminiferal G. subglobosa assemblage (upper part), the planktonic fossil assemblage B. metzmacheri and the dinoflagellate Achomosphaera sp. 1 Assemblage Zone (Fig. 10). Two Sr. analyses in the upper part of this unit give the ages of approximately 5.2 and 5.8 Ma (Fig. A1). These ages are somewhat younger than the occurrence of B. metzmacheri in the North Atlantic and Norwegian Sea (approximately 10.0-8.7 Ma, Spiegler & Müller 1992, Müller & Spiegler 1993). The young Sr. isotope ages may be explained by the fact that the samples could have contained caved tests, since the analysed benthic foraminiferal taxa also occur in the immediately overlying assemblage. Unfortunately, the B. metzmacheri tests were too small and too few to be used for the analyses. 

Lower Miocene (Brygge Formation)

Lower Miocene sediments are observed in well 6407/9-5 corresponding to the benthic foraminiferal G. subglobosa (lower part). G. subglobosa is known from Early Miocene deposits in the North Sea, but the presence of this species in this unit may be caved from the two immediately overlying assemblages. Lower Miocene deposits also correspond to planktonic fossil Diatom sp. 4 assemblage and the dinoflagellate C. cantharellum Zone.

Lower Oligocene

Lower Oligocene deposits are recorded in all wells (Fig. 10). In well 6407/9-5 these sediments correspond to the benthic foraminiferal R. bulimoides assemblage and the dinoflagellate A. semicirculata and S. cooksoniae zones. In well 6407/9-2 this unit corresponds to the benthic foraminiferal S. compressa and A. scitula assemblages, the planktonic fossil Diatom sp. and Diatom sp. 3 assemblages and the dinoflagellate A. semicirculata and S. cooksoniae zones. In well 6407/9-1 the Lower Oligocene corresponds to benthic foraminiferal G. soldanii girardana, T. alsatica, G. soldanii mamilata and R. bulimoides assemblages and the dinoflagellate Achomosphaera sp. 1 Assemblage Zone (lower part) and A. semicirculata Zone. The occurrence of Achomosphaera sp. 1 in the Lower Oligocene is probably caved. One Sr. analysis in the upper part of the unit in well 6407/9-5 give an age of approximately 30.3 Ma, and one analysis somewhat lower down in the unit in well 6407/9-1 give an age of 32.4 Ma. These ages confirm the bistratigraphic correlations.      

Shallow cores in the Nordland Ridge area

Previous studies

Sediments from the seismic unit IX, corresponding to the coastal deposits, were sampled with vibro corer, piston corer and grab by Continental Shelf Institute (IKU). Lithological and micropaleontological descriptions and interpretations of the sediments were reported in the unpublished report of Skarbø et al. (1983). The main results were published in Bugge et al. (1984). These authors gave the coastal deposits an Early Oligocene age. Our evaluation of the dinoflagellate flora, described in Skarbø et al. (1983), indicates that taxa are forms with a range of Oligocene to Middle Miocene. However, all taxa are probably reworked in the light the new ages given to the distal part of the coastal deposits, in the wells 6407/9-1, /9-2 and /9-5, in the Draugen Field. 

Sites

According to Skarbø et al. (1983) sediments were sampled at the sites B82-1984 (66°48’39”N, 10°42’13”E, vibro corer), B82-1985/2 (66°46’17”N, 10°43’43”E, piston corer), B82-186/5 (66°43’21”N, 10°38’01”E, vibro corer), B82-187/4 (66°43’26”N, 10°32’43”E, grab), B82-189/2 (66°38’03”N, 10°33’33”E, vibro corer) and B82-191/2 (66°37’53”, 10°47’53”, piston corer, Fig. 1).

Lithology

Skarbø et al. (1983) describe the sediments as rust-stained, yellow sand with rounded pebbles. Quartz and goethite dominate the sand, but glauconite is very frequent in the fine to medium fraction.

Palynological investigations

According to Skarbø et al. (1983) were six samples analysed from the sites within this seismic unit (B82-185/2 (two samples), B82-186/5, B82-187/4, B82-189/2 and B82-191/2.  None of the samples yielded age diagnostic dinoflagellate cyst of Late Miocene to Early Pliocene age.

A rich and diverse assemblage of reworked dinoflagellate cysts with an Oligocene-Middle Miocene affinity was recorded in the sample from B82-187/4 including Spiniferites ramosus subsp. granomenbranaceous, Thalassiphora cf. delicata, Tectatodinium cf. pelliferum and particularly Palaeocystodinium golzowense. Samples from sites B82-185/2, B82-186/5 and B82-189/2 are nearly barren although some evidence of Cainozoic sediments is present. B82-185/2 and B82-186/5 contain middle Creataceous forms whereas some Callovian to Oxfordian forms are present in B82-189/2.

Sample B82-191/2 contains Eocene dinoflagellate cysts Lentinia wetzelii and Dracodinium varielongitum. None of the species recorded from this sample are restricted to post Eocene strata, and the site is close to the eastern margin of the seismic unit and to Eocene outcropping strata (Skarbø et al. 1983).

Micropaleontological investigations

Skarbø et al. (1983) did not report foraminifera from these sites, but they probably recorded some caved forms. T. Eidvin (personal observation, 1995) analysed one very large sample each from B82-185/2 and B82-186/5 and found only Pliocene to Holocene forms. No Pliocene foraminiferal index forms were seen, indicating that the fossils are no older than the Pleistocene. The tests have a white, unstained and unworn appearance, typically of late Weichselian and Holocene sediments. All these tests were probably caved and mixed with the sampled material during coring.

Well 6510/2-1 on the Vega High

Well location, material and methods

Well 6510/2-1 (65°47’15.60’’N, 10°25’51.33’’E, Fig.1) is the southernmost well drilled in the proximal part of the Molo Formation. The seafloor is 325 mbms (meters below mean sea level), and the well was drilled down to 1224 m RKB with no return of drill cuttings to the rig. The interval 441-722 m was sampled with sidewall cores. The upper part of this interval (sidewall core samples 441 to 480 m) corresponds to the sandy coastal deposits.

A number of 14 sidewall cores were analysed for dinoflagellates and ten samples analysed for foraminifera. From 11-36 g material was available from the cores. The foraminiferal identification was done in the 106-500-mm fraction. In some cases the fraction larger than 500-mm was also studied. Material less than 106-mm was saved for palynological analyses.

Foraminiferal assemblages

Foraminifera of quite poor diversity and assemblage composition occur in most of the investigated samples. One sample is barren of foraminifera, one interval contains only reworked and caved forms, and one interval contains only species with very long stratigraphic ranges.

UNDEFINED INTERVAL

Material: One sidewall core at 441 m.

Age: Post mid-Miocene (based on seismic interpretation and regional considerations).

Lithostratigraphic unit: Molo Formation.

Assemblage: This interval is barren of foraminifera.

UNDEFINED INTERVAL

Depth range: 455-480 m.

Material: Two sidewall cores at 455 and 480 m.

Age: Post mid-Miocen (based on seismic interpretation and regional considerations).

Lithostratigraphic unit: Molo Formation.

Reworked assemblage: A. guerichi staeschei is scarce in the uppermost sample, but is quite common in the lowermost sample. One specimen of P. bulloides is also recorded in the lowermost sample (Fig. A7). All of the tests are eroded. 

Caved assemblage: A few specimens of Bulimina marginata, Elphidium sp., Islandiella islandica, Uvigerina peregrina, Dentalina sp., Hyalinea baltica, Pyrgo williamsoni and N. pachyderma (sinistral, encrusted). All the tests have a white, unstained and unworn appearance, typically of late Pleistocene and Holocene deposits.

Remarks: The two sidewall cores in this interval contained unconsolidated sands saturated with drillings fluids. It was not possible to remove the drilling fluids during the microfossil preparation process. These fluids were probably the source of the Pleistocene and Holocene fossils. King (1989) described A. guerichi staeschei from basal Lower to basal Middle Miocene sediments in the North Sea area. P. bulloides is described from the Oligocene to recent deposits (Batjes 1958, Mackensen et al. 1985). The occurrence of P. bulloides may consequently be in situ. However, it is most likely reworked since the sole specimen is clearly eroded. It is not likely caved since this species is only known from deep water, continental slope sediments in Pleistocene and recent deposits (Mackensen et al. 1985, T. Eidvin personal observation). Probably no one of the foraminifera recorded in this interval are in situ.

UNDEFINED INTERVAL

Depth range: 502-589 m.

Material: Seven sidewall cores at 502, 511, 519, 567, 575, 582 and 589 m.

Age: ?Early Oligocene-Early Eocene (based on palynological evidence).

Lithostratigraphic unit: Brygge Formation.

Assemblage: Only rare, agglutinated foraminifera occur in this interval. Ammodiscus sp., Bathysiphon sp., Haplophragmoides sp., Rhizammina sp. and Textulariina sp. are recorded (Fig. A7).

Remarks: No age diagnostic foraminifera are found in this interval, and only a general Paleogene age can be inferred on the basis of the foraminifera.   

Dinoflagellate cyst zones

The samples examined for palynology contained relatively rich and diverse assemblages of dinoflagellate cysts. Age interpretation based on dinoflagellates is, however, not straight forward, since several samples contain common reworked Paleogene (and Mesozoic) specimens.

UNDEFINED INTERVAL

Depth range: 441-480 m.

Material: Three sidewall cores at 441 m, 455 m and 480 m.

Age: Post mid-Miocene (based on seismic interpretation and regional considerations).

Lithostratigraphic unit: Molo Formation.

Description: The interval contains common to abundant reworked Paleogene to mid-Miocene dinoflagllate cysts, and only a few post younger Neogene specimens. The two upper samples are characterised by abundant (441 m) to common (455 m) Cyclopsiella granosa, together with abundant Paralacaniella indentata (Fig. A8). The Pliocene-Pleistocene species Selenopemphix brevispinosa and Spiniferites mirabilis are recovered in the sample at 441 m. The sample from 480 m contains Spiniferites elongatus, Nematopshaeropsis labyrinthus, Selenopemphix quanta and Invertocysta lacrymosa.

Remarks: The recovery of Selenopemphix brevispinosa at 441 m may suggest an Early Pliocene age at this level. Hystrichosphaera obscura found at 441 m, has a last occurrence datum in Late Miocene, but this species also range into strata as old as Oligocene. Matsuoka & Head (1992) reports an Early to Late Miocene age for Cyclopsiella granosa based on several published observations in the North Atlantic Ocean. In a recent study on the impact of the onset on major Northern Hemisphere glaciations on dinoflagellate cyst assemblages in the Mediterranean and the North Atlantic (DSDP Site 607) Versteegh (1997) found that the LAD of Invertocysta lacrymosa appears to be a valuable marker for the isotop stage 110. In ODP Site 986 Smelror (1999) noted the LAD of this species in sediments interpreted to lie within the Matuyama paleomagnetic chron (Channell et al. 1999), i.e. close to ~ 2.6 Ma.

AREOLIGERA SEMICIRCULATA ZONE

Definition: The body of strata between the highest/youngest occurrence of Areoligera semicirculata and the highest/youngest occurrence of Svalbardella cooksoniae.

Material: One sidewall core at 502 m.

Age: Early Oligocene.

Lithostratigraphic unit: Brygge Formation.

Decription: The assemblage is characterised by abundant Areosphaeridium arcuatum, common Deflandrea phosphoritica and Phatanoperidinium comatum, and the presence of Corrudinium incompsitum, Criproperidinium giuseppei, Melitasphaeridium asterium and Areoligera semicirculata (Fig. A8). 

Reworked assemblage: Paleoperidinium pyrophorum is possibly reworked from Upper Palaeocene or older strata, while Atopodinium haromense is reworked from the lower Middle or Upper Jurassic.

Remarks: The presence of Areoligera semicirculata gives firm evidence of an age not younger than Early Oligocene (i.e. 28.5 Ma according to Williams & Manum, 1999). The presence (acme) of Areosphaeridium arcuatum supports this interpretation.

HETERAULACACYSTA POROSA ZONE

Category: Informal local taxon range zone.

Informal local boundary criteria: The top and base of the zone is defined by the highest and lowest occurrence of Heteraulacacysta porosa respectively.

Material: One sidewall core at 511 m.

Age: Late Middle Eocene (Bartonian).

Lithostratigraphic unit: Brygge Formation.

Description: the sample at 511 m is characterised by abundant Phthanoperidinium geminatum, together with P. clinthridum and Heteraulacacysta porosa.

Remarks: H. porosa found in this sample is a good marker for the Middle Eocene (i.e. upper  NP16 to NP17 Zones, Powell 1992, Bujak 1994). The presence of Pthtanoperidinium clinthridum and common Pthtanoperidinium geminatum support this age-interpretation (Fig. A8). In their study of ODP Site 643 on the Vøring Plateau, Manum et al. (1989) found H. porosa in one single sample (104-643-51-1) within their Middle Eocene Areosphaeridium arcuatum Zone.

EATONICYSTA URSULAE ZONE

Category: Concurrent range zone.

Informal local boundary criteria: The top of the zone is defined by the highest occurrence (LAD) of Eatonicysta ursulae, and the base of the zone is defined by the highest occurrence (LAD) of Deflandrea oebisfeldensis.

Depth range: 519-587 m.

Material: Five sidewall cores (519 m, 567 m, 575 m, 582 m and 587 m).

Age: Late Early-early Middle Eocene.

Lithostratigraphic unit: Brygge Formation.

Description: This zone is characterised by the presence of Eatonicysta ursulae and Hystrichosphaeropsis costae. Other typical species are Cerebrocysta bartonensis, Rottnestia borussica and Areosphaeridium michoudii (Fig. A8).

Remarks: The presence of Eatonicysta ursulae at 519 m gives an age not younger than early Middle Eocene (i.e. equivalent to NP15 Zone) at this level (Powell 1992). The presence of Hystrichosphaeropsis costae in the same sample support this interpretation (following the top range of this species given in Bujak1994). The youngest occurrence of Cerebrocysta magna further suggests an age not younger than middle NP15 Zone at 567 m. The presence of Adnatosphaeridium vittatum at 582 m indicate an age not older than middle NP12 Zone at this level. The occurrence of Dracodinium varielongitidum at 575 m, 582 m and 587 m suggest an age not older than middle Early Eocene (NP 12 Zone) down to 587 m: Deflandrea granulata is present between 575-587 m. The lowest occurrence of this species defines the base of the Deflandrea sp. B Zone of Manum et al. (1989). The underlying A. vittatum Zone of Manum et al. (1989) was defined as the interval from the lowest occurrence of A. vittatum to the lowest occurrence of Deflandrea sp. B (herein recorded as D. granulata). In well 6510/2-1 A. vittatum has only been found in a single sample at 582 m, together with D. granulata. While Manum et al. (1989) dated the oldest occurrence of A. vittatum as Middle Eocene, Powell (1992) placed the FAD of this species within the mid Ypresian.

UNDEFINED INTERVAL

Depth range: 591-593 m.

Material: Two sidewall cores at 591 m and 593 m.

Age: ?Early Eocene.

Lithostratigraphic unit: Brygge Formation.

Description: This interval contains a charcteristic Early Eocene dinoflagellate cyst assemblage which includes Areosphaeridium dictyoplokus, A. michoudii, Deflandrea phosphoritica, Rottnestia borussica, Thalassiphora delicata, T. pelagica, Wezelialla ovalis and Cordosphaeridium funiculatum.

Remarks: An Early Eocene age (equivalent to NP Zone 12) can probably be extended down to 593 m based on the presence of Cribroperidinium tenuitabulatum, Deflandrea phosphoritica, Wetzeliella ovalis, Areosphaeridium dictyoplokus and Rottnestia borussica (Fig. A8). According to Powell (1992) both A. dictyoplokus and W. ovalis have their oldest appearances in beds age-equivalent to the middle Ypresian NP12 Zone. The presence of Alisocysta margarita and Isabelidinium ?viborgense at 593 m is taken as evidence of reworking from the Upper Palaeocene. Reworking from the Lower Cretaceous is seen from the presence of Speetonia sp., Sirmiodinium grossii and Dingodinium cerviculum.

ALISOCYSTA MARGARITA ZONE

Category: Informal local taxon range zone.

Informal local boundary criteria: The top and the bottom of the zone are defined by the highest and lowest occurrence of A. margarita.

Depth range: 701-722 m.

Material: Two sidewall cores at 701 m and 722 m.

Age: Late Palaeocene to Early Eocene.

Lithostratigraphic unit: Tare Formation.

Description: This zone is characterised by the presence of Alisocysta margarita, Deflandrea oebisfeldensis, Cerodinium striatum and Apectodinium spp (Fig. A8).

Remarks: The presence of common A. margarita, together with abundant Cerodinium speciosum at 701 m is good evidence for a Late Palaeocene age at this level.

According to Powell (1992) A. margarita does not range above beds age-equivalent to NP Zone 8. In the sample at 722 m these two species occur together with Apectodinium hyperacanthum and Apectodinium quiquelatum. According to Powell (1992) the two latter species do not range below the NP9 Zone. These ranges are not consistent with the observations from the sample at 722 m. Schroder (1992), however, noted an overlap between the ranges of A. cf. margarita and Apectodinium spp. in the zonation developed for Shell U.K. for the Palaeocene of the North Sea Basin. Following the Shell zonation the samples at 701-722 m can be related to Zone PT19.1 (and lowermost 19.2).

Strontium isotope stratigraphy

Three samples, with tests of calcareous foraminifera taken from the sidewall core at 480 m, were analysed for strontium isotopes. One sample containing tests of presumed reworked A. guerichi staeschei gave a corrected ⁸⁷Sr/⁸⁶Sr-ratio of 0.708672. On the seawater Sr isotope curve of Howarth & McArthur (1997) this ⁸⁷Sr/⁸⁶Sr-ratio corresponds to an age of approximately17.2 Ma (late Early Miocene, Table 1, Fig. A7).

The two other Sr samples from the sidewall core at 480 m contained tests of presumed caved Pleistocene – Holocene forms. The ⁸⁷Sr/⁸⁶Sr-ratios of these samples correspond to very young ages (Nødtvedt 1999).

Stratigraphical conclusion for well 6510/2-1

Interval 441-480 m (Molo Formation, post mid- Miocene)

No specific foraminifera and dinoflagellate cyst zonal markers are recoverd from the Molo Formation in this well, and Sr-age of 17 Ma is derived from reworked foraminifera. However, the presence of the dinoflagellate cysts Selenopemphix brevispinosa (441 m) and Invertocysta lacrymosa (480 m) may be indicative of a Late Miocene - Early Pliocene age, but these species are also know to range into older Neogene strata. 

Sample at 502 m (Brygge Formation, ?Lower Oligocen)

Dinoflagellates attributed to the A. semicirculata Zone indicate an Early Oligocene age for this sample. No age diagnostic foraminifera are found and the foraminifera indicate only a general Paleogene age.

Sample at 511 m (Brygge Formation, Upper part of Middle Eocene)

Dinoflagellates attributed to the H. porosa Zone date this sample to late Middle Eocene. The foraminifera indicate only a general Paleogene age.

Interval 519-589 m (Brygge Formation, Upper part of Lower Eocene-lower part of Middle Eocene)

Dinoflagellates attributed to E. ursulae Zone date this interval to late Early-early Middle Eocene. The foraminifera indicate only a general Palaeogene age.

Interval 591-593 m (Brygge Formation, ?Lower Eocene)

The dinoflagellates indicate an Early Eocene age for this interval.

Interval 701-702 m (Tare Formation, Upper Palaeocene-Lower Eocene)

Dinoflagellates attributed to the Alisocysta margarita Zone date this interval to Late Palaeocene.

Lithology

The sidewall cores at 441, 455 and 480 m, which represent the Molo Formation contain quite coarse sand. The sand contains mainly glauconite (dominant) and quartz grains, which are angular to sub-angular. Many of the quartz grains are rust-stained.

The sidewall cores at 502, 519, 567, 575, 582, 587, 591 and 593 m which represent the Brygge Formation of ?Early Eocene to ?Early Oligocene age and the sample 701 m of uppermost Tare Formation of Late Paleocene – Early Eocene age contain mostly muddy, micaceous siltstones. The sample at 511 m of the Brygge Formation is, however, quite sandy, but the sand is not as course as the sand of the Molo Formation. The sand contains quartz, mica and a smaller portion glauconite.

The lowermost sample at 702 m of the Tare Formation is also dominated of sand. This sand is quite coarse and there is also recorded several pebbles. It is quite similar to the sand of the Molo Foramation regarding mineralogy, grain forms and colour, but is even coarser.

Revised palynostratigaphy of well 6610/3-1 on the Nordland Ridge

Previous studies

Information on foraminiferal and palynological biostratigraphy and strontium isotope analyses from the Molo Formation in well 6610/3-1 (66°55’29.70’’N, 10°54’6.28’’E, Fig. 1) has previously been published by Eidvin et al. (1998a). Their study included 5 sidewall cores from the interval between 460–555 m. From their findings they concluded that the Molo Formation in this well was of Early Oligocene age, although the foraminifera found in the interval are known to have a longer Early Oligocene to Early Miocene range in the North Sea area. The strontium isotope ages obtained from 525 m and 555 m, however, pointed towards Early Oligocene and Late Eocene ages of 35.9 Ma and 39.8 Ma, respectively (33.6 Ma and 36.9 Ma on the new strontium isotope curve of Howarth & McArthur (1997) and the time scale of Berggren et al. (1995)). The lowermost sample was believed to be contaminated, and the upper analysed sample was regarded as most reliable. One new alalysis of foraminifera from 555 m gave an age of 37.5 Ma (Table 1, Fig. A9). According to Eidvin et al. (1998a) the dinoflagellate cyst assemblages from this interval contain a mixture of Jurassic, Palaeocene and Early Eocene-Early Oligocene species.       

Material and methods

The re-analysing of the marine palynomorphs is based on the five samples analysed by Eidvin et al. (1998a). In addition six more samples from the immediately underlying section are used. The same kind of preparation methods were used for these samples as for the samples in the wells 6407/5-1, 6407/5-2 and 6407/5-5.

Dinoflagellate cyst zones

UNDEFINED INTERVAL

Depth range: 460-555 m.

Material: Five side wall cores at 460 m, 480 m, 502 m, 525 m and 555m.

Age: Post mid-Miocene (based on seismic interpretation and regional considerations).

Lithostratigraphic unit: Molo Formation.

Description: The dinoflagellate cyst assemblages from this interval is totally dominated reworked Paleogene and Meosozoic dinoflagellate species. A few taxa which may be in situ include Batiacasphaera spp., Spiniferites spp., Reticulatosphaera actinocoronata and Operculodinium centrocarpum (Fig. A9).

Remarks: The single occurrence of Reticulatosphaera actonocoronata at 525 m may indicate a correlation to the Early Pliocene Reticulatosphaera actonocoronata Zone. However, this species has a long range in the Cainozoic, and may thus be reworked along the other abundant reworked Tertiary dinoflagellate cysts. 

UNDEFINED INTERVAL

Material: Two sidewall cores at 585.5 m and 611 m.

Age: ?Middel Eocene (Bartonian).

Lithostratigraphic unit: Brygge Formation.

Description: The assemblage is a rich and relative diverse marine microflora, which include several typical Eocene species, including Enneadocysta pectiniformis (abundant at 555 m), E. arcuata, E. fenestrata, Rottnestia borussica, Areosphaeridium dictyoplokus, Corrudinium incompositum, Cribroperidinium giuseppei, Cerebrocysta bartonensis and Samlandia chalmydophora.

Remarks: The presence of Enneadocysta fenestrata at 611 m (Fig. A9) points to an age not younger than early Late Eocene (early Priabonian), while the record of Rottnestia bourssica in the same sample restricts the age to not younger than latest Middle Eocene (Powell 1992, Bujak & Mudge 1994). The appearance of Corrudinium incompositum up to the sample at 585.5 m is further an evidence for a Middle Eocene age for this interval (following the range for this species given in Powell, 1992). Reworked dinoflagellate cysts include Endoscrinium pharao (Late Jurassic-Early Cretaceous) found at 585.5 m. 

HETERAULACACYSTA POROSA ZONE

Category: Informal local taxon range zone.

Informal local boundary criteria: The top and base of the zone is defined by the highest and lowest occurrence of Heteraulacacysta porosa respectively.

Material: Two sidewall cores at 643 m and 684m.

Age: Late Middle Eocene (Bartonian).

Lithostratigraphic unit: Brygge Formation.

Description: Characteristic species from this zone include Heteraulacacysta porosa, Areosphaeridium michoudii, Glaphyrocysta exuberans, Diphyes pseudofiscusoides and Cerebrocysta bartonensis (Fig. A9).

Remarks: Heteraulacacysta porosa found in both samples from this zone is a good marker for the Middle Eocene (i.e. upper NP16 to NP17 Zones, Powell 1992, Bujak 1994)

DIPHYES COLLIGERUM ZONE

Definition: The body of strata between the highest/youngest occurrence of Diphyes colligerum and the highest/youngest occurrence of abundant Systematophora placacantha (Bujak & Mudge 1994).

Depth range: 715-733 m.

Material: Two sidewall cores at 715 m and 733 m.

Age:  Middle Eocene (late Luetian).

Lithostratigraphic unit: Brygge Formation.

Description: This zone is characterised by the presence of Diphyes colligerum, together with Areosphaeridium dictyoplokus, Corrudinium incompositum, Distatodinium craterum and Rottnestia borussica (Fig. A9).

Remarks: According to Powell (1992) Corrudinium incompositum and Distatodinium craterum have their oldest appearances in beds age-equivalent to the upper Lutetian NP16 Zone: The presence of Apectodinium augustum at 733 m is taken as evidence of reworking from the Upper Palaeocene.

Stratigraphy of well 6610/2-1S on the Nordland Ridge

Well location, material and methods

Well 6610/2-1S (66°48’48.73’’N, 10°30’26.70’’E) was drilled just to the west of well 6610/3-1 (Fig. 1). In well 6610/2-1S the sediments immediately under the Molo Formation were sampled with ditch cuttings. A number of eleven sidewall cores were analysed for dinoflagellates and seven samples analysed for foraminifera. The same amount of material and the same kind of fossil preparation methods were used for well 6610/2-1S as for the wells 6407/5-1, 6407/5-2 and 6407/9-5.

Foraminiferal assemblages

The upper part of the of the analysed interval, from 950 to 1000 m, contains calcareous foraminiferal assemblages, while in situ agglutinated foraminifera are absent. In sample at 1010 m a marked change takes place from calcareous assemblages to mixed calcareous – agglutinated assemblages. It is supposed that this faunal turnover reflects a change in depositional conditions from shallow water (above) to deeper water (below).

TURRILINA ALSATICA ASSEMBLAGE

Definition: The top of the assemblage extends to the uppermost investigated sample. The base is marked by the highest occurrence of G. soldanii mamillata.

Depth range: 950-980 m.

Material: Three ditch cuttings samples at 950, 960 and 970 m.

Age: Early Oligocene (partly based on palynological evidence).

Lithostratigraphic unit: Brygge Formation.

Correlation: Subzone NSB 7b of King (1989) and Zones NSR 7A or 7B of Gradstein and Bäckström (1996).

Description: The fossil assemblage in this interval is dominated by radiolaria and pyritized diatoms. Benthic foraminifera are quite sparse, but include T. alsatica, Stilostomella adolphina, Q. seminulum and E. variabilis (Fig. A10).

Remarks: T. alsatica is known from the Lower Oligocene to the lowermost Lower Miocene succession in the North Sea (King 1989). According to Gradstein & Bäckström (1996) this species is known from the Lower Oligocene to the lowermost Upper Oligocene in the same area. S. adolphina is recorded from the upper part of the Lower Oligocene succession in Denmark (Ulleberg 1974).

GYROIDINA SOLDANII MAMILLATA – ROTALIATINA BULIMOIDES ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest occurrence of G. soldanii mamillata. The base is marked by the highest occurrence of Karrerulina conversa.

Depth range: 980-1010 m.

Material: Four ditch cutting samples at 980, 990, 1000 and 1010 m.

Age: Early Oligocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Subzone NSB 7a and Subzone NSB 7a of King (1989) and Zones NSR 7A or 7B of Gradstein & Bäckström (1996).

Description: This assemblage contains a moderately rich fossil assemblage of radiolaria, pyritized diatoms and benthic foraminifera. Radiolaria and pyritized diatoms are dominant in the upper part while benthic foraminifera are dominant in the lower part. Mainly calcareous benthic foraminifera are recorded, but a few agglutinated forms are found in the lowermost sample. No benthic foraminifera are common, but important taxa include T. alsatica, E. variabilis, A. scitula, G. soldanii mamillata, Cibicides tenellus, R. bulimoides, P. bulloides and Cassidulina carpitana (lower part, Fig. A10).

Remarks: In the North Sea area G. soldanii mamilliata is described from the Lower Oligocene to the lowermost Upper Oligocene according to King (1989) and from the Upper Eocene to the lowermost Upper Oligocene according to Gradstein & Bäckström (1996). R. bulimoides is known from the Lower Oligocene to the lowermost Upper Oligocene according to King (1989) and from the Upper Eocene to the Lower Oligocene according to Gradstein & Bäckström (1996). C. carpitana is described from Lower Oligocene deposits in the same arera. A. scitula is known from the Lower Oligocene to Lower Miocene in the North Sea and from the Lower Oligocene to the basal Middle Miocene in the Haltenbanken area according to Gradstein & Bäckström (1996). C. tenellus is known from Oligocene sediments in Belgium (Batjes 1958).

Dinoflagellate cyst zones

AREOLIGERA SEMICIRCULATA ZONE

Definition: The body of strata between the highest/youngest occurrence of Areoligera semicirculata and the highest/youngest occurrence of Svalbardella cooksoniae.

Depth range: 950-990 m.

Material: Four ditch cutting samples at 950 m, 960 m, 970 m and 980 m.

Age: Early Oligocene.

Lithostratigraphic unit: Brygge Formation.

Description: The zone contains abundant and relatively diverse dinoflagellate cysts assemblages. Areoligere semicirculata is common at 950 m and 960 m, while Spiniferites spp. is common to abundant throughout the zone. Characteristic species with last occurrences in the zone are Chiropteridium lobospinosum, Enneadocysta arcuata, Histocysta sp. 1 and Criborperidinium giuseppei (Fig. A11).

The zone contains reworked Late-Middle Eocene and Jurassic dinoflagellate cysts.

Remarks: According to Powell (1992) the last appearance datum (LAD) of A. semicirculata lays within the lower NP25 calcareous nannoplankton biozone in Britain and in the North Sea area. Manum et al. (1989) found that the LAD of this species (named Glaphyrocysta intricata in their publication) corresponded to the upper boundary of their Early/Late Oligocene Areosphaeridium? actinocoronatum in ODP Hole 643 in the Norwegian Sea. The LAD of this species also defines the upper boundary of the Oli4 Zone of Poulsen et al. (1996) as defined in ODP Hole 908 on the Hovgaard Ridge between Svalbard and NE Greenland. 

SVALBARDELLA COOKSONIAE ZONE

Category: Informal local taxon range zone.

Informal local boundary criteria: The top of the zone is placed at the last appearance datum (LAD) of S. cooksoniae, while the base is defined by the first appearance datum (FAD) of Areosphaeridium dictyoplokus.

Depth range: 990-1040 m.

Material: Five ditch cutting samples at 990m, 1000 m, 1010 m, 1020 m and 1030 m.

Age: Earliest Oligocene.

Lithostratigraphic unit: Brygge Formation.

Description: The zone contains abundant and relatively diverse dinoflagellate cysts assemblages. Spiniferites spp. are common to abundant throughout the zone, while Phthanoperidinium comatum is common at 1000-1030 m. Glaphyrocysta exuberans, Membranophoridium aspinatum, Pyxidiniopsis denespunctata and Phthanoperidinium geminatum have their last occurrences at the top of the zone (Fig. A11). 

Reworked assemblage: The zone contains reworked Late Paleocene, Cretaceous and Jurassic dinoflagellate cysts.

Remarks: In ODP Hole 643 Manum et al. (1989) found S. cooksoniae to have a restricted occurrence in the earliest Oliogocene. According to Williams & Manum (1999) the last appearance datum of S. cooksoniae can be calibrated to 32 Ma.

UNDEFINED INTERVAL

Depth range: 1040-1050 m.

Material: Two ditch cutting at 1040m and 1050 m.

Age: Middle Eocene.

Lithostratigraphic unit: Brygge Formation.

Description: This interval contains relative abundant and diverse Middle Eocene marine microfloras. An age not younger then Middle Eocene at 1040 m is inferred by the last appearance datum of Cassiculosphaera magna at this level. According to Bujak & Mudge (1994) the youngest occurrence of this species is within middle NP15 Zone. The presence of Cerebrocysta bartonensis at 1040 m and Rottnestia borussica at 1050 (Fig. A11) are further taken as evidence for an age not younger than Middle Eocene for this un-zoned interval. The single occurrence of Diphyes colligerum at 1050 m may suggest that strata correlatable to the Diphyes colligerum Zone is reached at this level. According to Bujak & Mudge (1994) the D. colligerum Zone is of Late lutetian age. The interval also contains reworked Late Paleocene dinoflagellate cysts. 

Strontium isotope stratigraphy

One samples based on tests of presumed in situ R. bulimoides and G. soldanii mamillata was analysed for strontium isotopes. The tests were picked from the ditch cuttings samples at 990, 1000 and 1010 m. The sample gave an corrected ⁸⁷Sr/⁸⁶Sr-ratio of 0.707886 corresponding to an age of approximately 32.2 Ma (Early Oligocene) on the seawater Sr isotope curve of Howarth & McArthur (1997, Table 1, Fig. A10).

Stratigraphical conclusion for well 6610/2-1S

Interval 950-1040 m (Brygge Formation, Lower Oligocene)

Dinoflagellates attributed to the A. semicirculata Zone and the S. cooksoniae Zone (950-1040 m) and benthic foraminifera attributed to the T. alsatica assemblage, G. soldanii mamillata – R. bulimoides assemblage (950-1010 m) date the interval to Early Oligocene. One strontium isotope analysis of foraminiferal tests corresponding to an age of approximately 32.2 Ma (990-1010 m) confirms the biostratgraphical correlations.

Interval 1040-1050 m (Brygge Formation, Middle Eocene)

Dinoflagellates date this interval to Middle Eocene.

Lithology

All the investigated samples in well 6610/2-1S contain silty mudstone.

Investigation of the Kai Formation

Stratigraphy and lithology of well 6609/11-1 on the Trøndelag Platform

Well location, material and methods

Well 6609/11-1 (66º08’13.90’’N, 09º33’47.89’’E, Fig.1) was drilled on the Trøndelag Platform, west of the area where the Molo Formation wedges out, and sampled the Kai Formation. A number of 25 ditch cutting were analysed for foraminifera, Bolboforma and diatoms, and 24 samples were analysed for dinoflagellates. The same amount of material and the same kind of fossil preparation methods were used for well 6609/11-1 as for the wells 6407/5-1, 6407/5-2 and 6407/9-5.

Micropalaeontological assemblages

The sections from Late Miocene to Late Pliocene contain moderately rich benthic faunas of mainly calcareous foraminifera. The planktonic fossil assemblages are sparse in these units except for the lower part of the Upper Miocene which contains a rich planktonic assemblage of Bolboforma, planktonic foraminifera, radiolaria and pyritized diatoms. The fossil assemblages in the Oligocene and Lower Miocene sections are dominated by radiolaria, pyritized diatoms and sponge spicules. Sparse faunas of agglutinated foraminifera and some calcareous forms are also recorded in most sections. The faunal turnover at the mid-Miocene unconformity reflects a change in depositional conditions from shallow water (above) to deeper water (below).

Benthic foraminiferal assemblages

CIBICIDES GROSSUS ASSEMBLAGE

Definition: The top of the assemblage extends to the uppermost investigated sample (1180 m). The base is marked by the highest/youngest occurrence of C. telegdi.

Depth range: 1180-1240 m.

Material: Six ditch cutting samples.

Age: Late Pliocene.

Lithostratigraphic unit: Naust Formation.

Correlation: Zone NSB 15 of King (1989), Cibicides grossa zone of Stratlab (1988) and Zone NSR 12 B of Gradstein & Bäckström (1996).

Description: This unit contains a moderately rich benthic fauna of calcareous foraminifera. C. scaldisiensis is common throughout. Other characteristic taxa include C. grossus, N. affine (common in lower part), C. lobatulus, E. albiumbilicatum, E. hannai, B. marginata, B. tenerrima, E. excavatum, C. teretis and A. fluens (lower part, Fig. A12).

Remarks: The occurrence of C. grossus and E. hannai show that this unit is of Late Pliocene age (Doppert 1980, King 1989).

CIBICIDES TELEGDI ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of C. telegdi. The base is marked by the highest/youngest occurrence of E. pygmeus and G. subglobosa.

Depth range: 1240-1250 m.

Material: One ditch cutting sample.

Age: Late Miocene to Early Pliocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Probably Cibicides telegdi – Eponides pygmeus – Neogloboquadrina atlantica (dextral) zone of Eidvin et al. (1998a) and probably lower part of Melonis – Trifarina zone of Stratlab (1988).

Description: The sole sample which constitutes this unit contains a moderately rich benthic fauna of calcareous foraminifera. N. affine occurs most frequently. Other important species include C. telegdi, B. marginata, C. teretis and A. fluens (Fig. A12).

Remarks: Most of the recorded benthic specimens are known from sediments from almost the entire Neogene. However, C. telegdi is described from the Oligocene in Denmark and Germany (Grossheide & Trunko 1965, Hausmann 1964, Kummerle 1963, Ulleberg 1974). This species is recorded in deposits from the Oligocene to the Lower Pliocene in the North Sea and on the Norwegian Sea continental shelf (Stratlab 1988, Eidvin et al. 1998a, Eidvin & Rundberg 2001 and Eidvin & Rundberg this volume). Since taxa no older than Late Miocene are recorded in underlying units is this assemblage most likely of Late Miocene to Early Pliocene age.

EPONIDES PYGMEUS – GLOBOCASSIDULINA SUBGLOBOSA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of E. pygmeus and G. subglobosa. The base is marked by the highest/youngest occurrence of Uvigerina venusta saxonica.

Depth range: 1250-1260 m.

Material: One ditch cutting sample.

Age: Late Miocene to Early Pliocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Probably Ehrenbergina variabilis – Globigerina subglobosa - Neogloboquadrina atlantica (dextral) zone and Cibicides telegdi – Eponides pygmeus – Neogloboquadrina atlantica (dextral) zone of Eidvin et al. (1998a) and probably Globocassidulina subglobosa – Ehrenbergina variabilis zone and lower part of Melonis – Trifarina zone of Stratlab (1988).

Description: The sole sample which constitutes this unit contains a moderately rich benthic fauna of calcareous foraminifera. N. affine and C. teretis occur most frequently. Other characteristic species include E. pygmeus, G. subglobosa, C. telegdi and A. fluens (Fig. A12). 

Remarks: Most of the recorded benthic specimens, also in this unit, are known from sediments from almost the entire Neogene. However, E. pygmeus is described from the Oligocene in Denmark and Germany (Grossheide & Trunko 1965, Hausmann 1964, Kummerle 1963, Ulleberg 1974). This species is recorded in deposits from the Oligocene to the Lower Pliocene in the North Sea and on the Norwegian Sea continental shelf (Stratlab 1988, Eidvin et al. 1998a, Eidvin & Rundberg 2001 and Eidvin 6 Rundberg this volume). G. subglobosa is recorded from the Oligocene to the Lower Pliocene in the North Sea (Eidvin & Rundberg 2001 and Eidvin & Rundberg this volume). Since taxa no older than Late Miocene are recorded in the immediately underlying unit, this assemblage is most likely of Late Miocene to Early Pliocene age.

UVIGERINA VENUSTA SAXONICA ASSEMBLAGE

Definition: The top and base of the assemblage is taken at the highest/youngest and lowest/oldest occurrence of U. venusta saxonica.

Depth range: 1260-1280 m.

Material: Two ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Subzone NSB 13b of King (1989).

Description: This assemblage contains a moderately rich benthic fauna of calcareous foraminifera. U. venusta saxonica occur most frequently. Other characteristic species include Chilostomellina fimbriata, N. affine, C. teretis, C. telegdi, E. pygmeus, G. subglobosa, P. bulloides and C. dutemplei (Fig. A12).

Remarks: According to King (1989) are U. venusta saxonica and C. fimbriata known from Upper Miocene to Lower Pliocene deposits in the North Sea area. Sr. analyses of tests of U. venusta saxonica from 1260 m gave an age of 6.3 Ma (Late Miocene) and consequently rule out an Early Pliocene age for this assemblage in well 6609/11-1.

UNDEFINED INTERVAL

Depth range: 1280-1290 m

Material: One ditch cutting sample.

Age: Early Miocene in the lower part and Late Miocene in the upper part (based on palynological evidence and log correlation).

Lithostratigraphic unit: Upper part of Brygge Formation and Kai Formation.

Description: This interval contains just a few, probably caved, benthic foraminifera (Fig. A12).

TRIFARINA GRACILIS VAR. A ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest occurrence of T. gracilis var. A (Batjes, 1958). The base of the assemblage is undefined.

Deptht range: One ditch cutting sample at 1290 m.

Age: Early Miocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Probably Zone NSB 10 or NSB 9 of King (1989) and probably Zone NSR 8B of Gradstein & Bäckström (1996).

Description: Just a few specimens of T. gracilis var. A, Martinottiella communis sp.

(agglutinated) and Cassidulina sp. are recorded in the sole sample of this unit (Fig. A12).

Remarks: According to Skarbø & Verdenius (1986) are T. gracilis var. A known from Upper

Oligocene to Lower Miocene sediments on the Norwegian continental shelf, and M. communis is described from the Miocene in the same area.

UNDEFINED INTERVAL

Depth range: 1300-1375 m.

Material: Eight ditch cutting samples.

Age: Oligocene to Early Miocene (based on planktonic fossil and palynological levidence).

Lithostratigraphic unit: Brygge Formation.

Description: Just a few undetermined agglutinated foraminifera are recorded in this interval.

BATHYSIPHON EOCENICUS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of B. eocenicus. The base is marked by the highest/youngest occurrence of Spiroplectammina spectabilis.

Depth range: 1375-1410 m.

Material: Four ditch cutting samples.

Age: Late Eocene to Early Oligocene (partly based on palynological evidence).

Lithostratigraphic unit: Brygge Formation.

Correlation: Probably Zone NSA 7 and NSA 8 of King (1989) and probably Zone NSR 7A and NSR 7B of Gradstein & Bäckström (1996).

Description: This interval contains a sparse fauna of mainly agglutinated foraminifera. Recorded species include B. eocenicus, S. compressa and Ammodiscus sp. (Fig. A12).

Remarks: B. eocenicus is known from Eocene to Lower Oligocene deposits in the North Sea area. Spirosigmoilinella sp. A (synonymous with S. compressa) is known from the Lower Oligocene to Lower Miocene succession in the North Sea (King, 1989). According to Gradstein & Bäckström (1996) is this species known from the Middle Eocene to the Upper Oligocene in the North Sea and from the Middle Eocene to the Lower Oligocene in the Haltenbanken area.

SPIROPLECTAMMINA SPECTABILIS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of S. spectabilis. The base is undefined.

Depth range: One ditch cutting sample at 1410 m.

Age: Middle Eocene (partly based on palynological evidence).

Lithostratigraphic unit: Brygge Formation.

Correlation: Zone NSA 5 of King (1989), Spiroplectammina spectabilis zone of Stratlab (1988) and probably Zone NSR 5A or NSR 5B of Gradstein & Bäckström (1996).

Description: Just a few specimens of S. spectabilis and Cyclammina rotundidorsata are recorded in the sole sample of this unit (Fig. A12).

Remarks: According to King (1989) is S. spectabilis known from the Lower to Middle Eocene in the North Sea area. According to Gradstein & Bäckström (1996) is this species described from upper Palaeocene to Middle Eocene deposits in the North Sea and the Haltenbanken areas. C. rotundidorsata is known from the Eocene to the Lower Miocene in the North Sea area according to Gradstein & Bäckström (1996).

Planktonic fossil assemblages

UNDEFINED INTERVAL

Depth range: 1180-1230 m.

Material: Five ditch cutting samples.

Age: Late Pliocene (based on benthic foraminiferal evidence).

Lithostratigraphic unit: Naust Formation.

Description: This interval is nearly barren of planktonic foraminifera. Just one specimen of N. pachyderma (dextral) is recorded (Fig. A12).

GLOBIGERINA BULLOIDES ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of G. bulloides. The base is marked by the highest/youngest occurrence of N. atlantica (sinistral).

Depth range: 1230-1240 m.

Material: One ditch cutting sample.

Age: Late Pliocene.

Lithostratigraphic units: Naust Formation.

Correlation: Globigerina bulloides Zone of Weaver & Clement (1986).

Descripton: Just a few specimens of G. bulloides and N. pachyderma (dextral) are recorded in the sole sample which constitutes this unit (Fig. A12).

Remarks: Weaver & Clement (1986) describe a G. bulloides Zone from the North Atlantic (DSDP Leg 94) in Late Pliocene sediments as young as 2.2 Ma. On the Vøring Plateau G. bulloides is common in Late Miocene to Late Pliocene deposits older than 2.4 Ma (Spiegler & Jansen 1989).

NEOGLOBOQUADRINA ATLANTICA (SINISTRAL) ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of N. atlantica (sinistral). The base is marked by the highest/youngest occurrence of B. laevis.

Depth range: 1240-1260 m.

Material: Two ditch cutting samples.

Age: Late Miocene to Early Pliocene.

Lithostratigraphic unit: Kai Formation.

Correlation: N. atlantica (sinistral) Zone of Weaver & Clement (1986) and Spiegler & Jansen (1989).

Description: The assemblage is characterized by a sparse fauna of planktonic foraminifera. Recorded species include N. atlantica (sinistral), G. bulloides and T. quinqueloba (Fig. A12).

Remarks: N. atlantica (sinistral) is known from the North Atlantic and the Vøring Plateau in Late Miocene to Late Pliocene sediments (Weaver & Clement 1986, Spiegler & Jansen 1989).

BOLBOFORMA LAEVIS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of B. laevis. The base is marked by the highest/youngest occurrence of B. subfragori.

Depth range: 1260-1270 m.

Material: One ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Bolboforma laevis/Bolboforma capsula Zone of Spiegler & Müller (1992) and Bolboforma laevis Zone of Müller & Spiegler (1993).

Description: The sole sample which constitutes this unit contains a sparse fossil assemblage of Bolboforma and planktonic foraminifera. B. laevis is the only Bolboforma species recorded. Recorded foraminifera include G. bulloides, N. atlantica (sinistral) and G. glutinata (Fig. A12).

Remarks: Spiegler & Müller (1992) and Müller & Spiegler (1993) have recorded a B. laevis/B. capsula Zone from the North Atlantic and a B. laevis Zone from the Vøring Plateau. These zones are described from deposits with an age of approximately 10.3-10.0 Ma.

BOLBOFORMA SUBFRAGORI ASSEMBLAGE

Definition: The top and base of the assemblage is taken at the highest/youngest and lowest/oldest occurrence of B. subfragori.

Depth range: 1270-1280 m.

Material: Two ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Bolboforma fragori/B. subfragori Zone of Spiegler & Müller (1992) and Müller & Spiegler (1993), Subzone NSP 14a of King (1983) and Bolboforma spiralis zone of Stratlab (1988).

Description: This unit is characterized by a rich fossil assemblage of radiolaria, pyritized diatoms, Bolboforma and planktonic foraminifera. Radiolaria, pyritized diatoms and Bolboforma are dominant, with subordinate foraminifera. B. subfragori is common. Other recorded Bolboforma include B. laevis, B. metzmacheri (one specimen) and B. fragori. Recorded planktonic foraminifera include N. pachyderma (caved), G. bulloides, Neogloboquadrina acostaensis and N. atlantica (dextral, Fig. A12).

Remarks: A B. fragori/B. subfragori Zone is known from deposits with an age of approximately 11.7-10.3 Ma from the North Atlantic and the Vøring Plateau (Spiegler & Müller 1992 and Müller & Spiegler 1993). Spiegler & Jansen (1989) describe a lower N. atlantica (dextral) Zone from Upper Miocene sediments on the Vøring Plateau. N. acostaensis is reported from deposits of Middle to Late Miocene age in the same area.

UNDEFINED INTERVAL

Depth range: 1280-1310 m.

Material: Three ditch cutting samples.

Age: Early Miocene in the lower part and Late Miocene in the upper part (based on benthic foraminiferal and palynological evidence).

Lithostraigraphic unit: Upper part of Brygge Formation and lower part of Kai Formation.

Description: This interval contains a rich planktonic fossil assemblage of pyritized diatoms and radiolaria, but no diatom index fossil is recorded (Fig. A12).

DIATOM SP. 4 ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of Diatom sp. 4. The base is marked by the highest/youngest occurrence of Diatom sp. 3.

Depth range: 1310-1350 m.

Material: Four ditch cutting samples.

Age: Early Miocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Zone NSP 10 of King (1983).

Description: This unit contains a rich planktonic fossil assemblage of radiolaria (dominant), and pyritized diatoms (including common Diatom sp. 4, Fig. A12).

Remarks: Diatom sp. 4 is described from Lower Miocene deposits in the North Sea area (King 1983).

DIATOM SP. 3 ASSEMBLAGE

Definition: The top and base of the assemblage is taken at the highest/youngest and lowest/oldest occurrence of Diatom sp. 3.

Depth range: 1350-1385 m.

Material: Five ditch cutting samples.

Age: Early to Late Oligocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Subzone NSP 9c of King (1989).

Description: Also this interval contains a rich planktonic fossil assemblage of radiolaria (dominant) and pyritized diatoms (including Diatom sp. 3, Fig. A12).

Remarks: Diatom sp. 3 is known from the upper part of Lower Oligocene to the lowermost part of Lower Miocene in the North Sea area (King 1989).

UNDEFINED INTERVAL

Depth range: 1385-1410 m.

Material: Four ditch cutting samples.

Age: Middle Eocene and Early Oligocene (based on benthic foraminiferal and palynological evidence).

Lithostratigraphic unit: Brygge Formation.

Description: This unit contain a rich planktonic fossil assemblage of pyritized diatoms and radiolaria (dominant), but no diatom or radiolarian index fossil is recorded (Fig. A12). 

Dinoflagellate cyst zones

The investigated Upper Pliocene succession contains few in situ dinoflagellate cysts (with typically less than 5 species present), but common to abundant reworked older Cenozoic and Mesozoic specimens. A slightly more rich and diverse marine microflora is encountered from the Lower Pliocene, and the abundance and diversity increases further downward into Upper-Middle Miocene strata. Rich and diverse dinoflagellate cyst assemblages are found in the Lower Miocene, Oligocene and Upper-Middle Eocene deposits, allowing a relatively detailed biostratigraphic breakdown of the interval between 1300-1410 m in the well.

UNDEFINED INTERVAL

Depth range: 1180-1240 m.

Material: Six ditch cutting samples.

Age: Late Pliocene (based on benthic and planktonic foraminiferal evidence).

Lithostratigraphic unit: Naust Formation.

Description: This interval contains only few in situ dinoflagellate cysts, but include common to abundant reworked older Cenozoic and Mesozoic specimens. The in situ marine microfloras include Batiacasphaera spp., Operculodinium centrocarpum and Spiniferites spp. (Fig. A13).

Remarks: There are no age-diagnostic dinoflagellate cyst species and the age of this interval is determined by the presence of the Cibicides grossus foraminiferal assemblage.

UNDEFINED INTERVAL

Depth range: 1240-1250 m.

Material: One ditch cutting sample.

Age: Late Miocene to Early Pliocene (based on benthic and planktonic foraminiferal evidence).

Lithostratigaphic unit: Kai Formation.

Description: The ditch cutting sample from 1240 m contains a low diversity dinoflagellate cyst assemblage comparable to those recovered from the Upper Pliocene sequence.

Remarks: There are no age-diagnostic dinoflagellate cyst species and the age of this interval is determined by the presence of the Cibicides telegdi foraminiferal assemblage.

ACHOMOSPHAERA SP. 1 ASSEMBLAGE ZONE

Definition: The body of strata defined by the presence of Achomosphaera sp. 1.

Depth range: 1250-1260 m.

Material: One ditch cutting sample.

Age: Late Miocene to Early Pliocene.

Lithostratigaphic unit: Kai Formation.

Description: The ditch cutting sample from 1250 m contains a moderate diversity of dinoflagellate cysts, including common Batiacasphaera together with Amiculosphaera umbracula, Achomosphaera sp. 1, Barssidinium graminosum and Hystrichokolpoma spp. (Fig. A13).

Remarks: This species has previously been consistently recorded in Lower Pliocene-Upper Miocene strata at ODP Sites 907, 908 and 909 in the Norwegian-Greenland Sea (Poulsen et al. 1996). The highest occurrence of Spiniferites pseudofurcatus at 1250 m may suggest that the age of the zone in this well is Late Miocene, rather than Early Pliocene. The presence of Middle – Late Miocene marker species Labyrintodinium truncatum in this zone is considered to be due to reworking.

UNDEFINED INTERVAL

Depth range: 1260-1290 m.

Material: Three ditch cutting samples.

Age: Early Miocene in the lower part (based on log correlation) and Late Miocene in the upper part (based on benthic foraminiferal and planktonic fossil evidence).

Lithostratigaphic unit: Upper part of Brygge Formation and lower part of Kai Formation.

Description: The interval contains moderate rich and diverse assemblages of dinoflagellate cysts, and recovered key species include Barssidinium graminosum, Spiniferites pseudofurcatus, Hystrichokolpoma spp., Hystrichosphaeropsis obscura and Reticulatosphaera actinocoronata (Fig. A13).

Remarks: The occurrence of Hystrichosphaeropsis obscura at 1270 m suggests an age older than 7.25 Ma according to the last occurrence datum for this species given by Smelror et al. (in press.).   

DISTATODINIUM PARADOXUM ZONE

Definition: The body of strata between the highest/youngest occurrence of Distatodinium paradoxum and the highest/youngest occurrence of Cribroperidinium tenuitabulatum (Smelror et al. in press).

Depth range: 1290-1300 m.

Material: One ditch cutting samples.

Age: Latest Early Miocene (partly based on benthic foraminiferal evidence).

Lithostratigaphic unit: Brygge Formation.

Description: The interval contains a fairly rich and diverse assemblage of dinoflagellate cysts. Recovered key species are Distatodinium craterum, Palaeocystodinium spp., Homotrybilum floripes, Tuberculodinium vancampoae, common Systematophora placacantha, Invertocysta tabulata and Palaeocystodinium sp. A Costa & Downie (1979, Fig. A13).

CRIBROPERIDINIUM TENUITABULATUM ZONE

Definition: The body of strata between the highest/youngest occurrence of Cribroperidinium tenuitabulatum and the highest/youngest occurrence of Cordosphaeridium cantharellum (Smelror et al. in press).

Depth range: 1300-1310 m.

Material: One ditch cutting samples.

Age: Early Miocene.

Lithostratigaphic unit: Brygge Formation.

vv

Description: The interval contains a fairly rich and diverse assemblage of dinoflagellate cysts. Recovered key species include Apteodinium spiridoides, Cribroperidinium tenuitabulatum, Distatodinium craterum, Spiniferites pseudofurcatus, Palaeocystodinium spp., Homotrybilum floripes, Tuberculodinium vancampoae and common Systematophora placacantha (Fig. A13).

Remarks: The present Cribroperidinium tenuitabulatum Zone can be correlated to Mio2 Zone as defined by Poulsen et al. (1996) at ODP Site 909 in the Greenland-Spitsbergen Sill. 

CORDOSPHAERIDIUM CANTHARELLUM ZONE

Definition: The body of strata between the highest/youngest occurrence of Cordosphaeridium cantharellum and the highest/youngest occurrence of Caligodinium amiculum (Smelror et al. in press).

Depth range: 1310-1325 m.

Material: One ditch cutting samples.

Age: Mid Early Miocene.

Lithostratigaphic unit: Brygge Formation.

Description: The zone contains a fairly rich and diverse assemblage of dinoflagellate cysts. Recovered key species include Cordosphaeridium cantharellum, Cribroperidinium tenuitabulatum, Distatodinium spp., Spiniferites pseudofurcatus, Palaeocystodinium spp. and common Systematophora placacantha (Fig. A13).

Remarks: Powell (1992) calibrated the LAD of Cordosphaeridium cantharellum to the lower NN 4 Zone in the British Tertiary, while de Verteuil & Norris (1996) placed the LAD in the upper NN 2 in their study on the Miocene of the U.S. Atlantic Margin. Williams and Manum (1999) give an age of 17.95 Ma for the LAD of C. cantharellum, which is in agreement with a calibration to the lower NN 4 Zone.

CHIROPTERIDIUM SPP. ZONE

Definition: The body of strata between the highest/youngest occurrence of Chiropteridium spp. and the highest/youngest occurrence of Distatodinium biffii (Smelror et al. in press).

Depth range: 1325-1355 m.

Material: Three ditch cutting samples.

Age: Late Oligocene (lowermost part) to Early Miocene (partly based on planktonic fossil evidence).

Lithostratigaphic unit: Brygge Formation.

Description: The zone contains a relatively rich and diverse marine microflora. Characteristic and common species of this zone are Chiropteridium spp., Deflandrea phosphoritica, Caligodinium spp., Homotrybilum floripes and Cordosphaeridium cantharellum (Fig. A13).

DISTATODINIUM BIFFII ZONE

Definition: The body of strata between the highest/youngest occurrence of Distatodinium biffii and the highest/youngest occurrence of Areoligera semicirculata.

Depth range: 1325- 1365 m.

Material: One ditch cutting sample.

Age: Late Oligocene.

Lithostratigaphic unit: Brygge Formation.

Description: The zone contains a relatively rich and diverse marine microflora. In overall character the dinoflagellate cyst assemblage in this zone resemble that over the overlying Chiropteridium spp. Zone, the main difference being the presence of Distatodinium biffii in the present zone (Fig. A13).

Remarks: According to Brinkhuis & Biffii (1993) and de Verteuil & Norris (1996) the last occurrence datum of D. biffii is found just below the Oligocene/Miocene boundary in the Mediterranean and on the US Costal Plain. A concurrent last appearance datum is also well documented in the Norwegian-Greenland Sea by Smelror et al. (in press.).

AREOLIGERA SEMICIRCULATA ZONE

Definition: The body of strata between the highest/youngest occurrence of Areoligera semicirculata and the highest/youngest occurrence of Svalbardella cooksoniae.

Depth range: 1365-1375 m.

Material: One ditch cutting sample.

Age: Early Oligocene.

Lithostratigaphic unit: Brygge Formation.

Description: The zone contains a relatively rich and diverse marine microflora. Characteristic for this zone in well 6609/11-1 is the acme of Areoligeras semicirculata, and the presence of Chiropteridium lobospinosum and Evittosphaerula paratabulata which are restricted to this zone in the well (Fig. A13).

Remarks: According to Powell (1992) the last appearance datum (LAD) of A. semicirculata lays within the lower NP25 calcareous nannoplankton biozone in Britain and in the North Sea area. Manum et al. (1989) found that the LAD of this species (named Glaphyrocysta intricata in their publication) corresponded to the upper boundary of their Early/Late Oligocene Areosphaeridium? actinocoronatum in ODP Hole 643 in the Norwegian Sea. The LAD of this species also defines the upper boundary of the Oli4 Zone of Poulsen et al. (1996) as defined in ODP Hole 908 on the Hovgaard Ridge between Svalbard and NE Greenland. 

SVALBARDELLA COOKSONIAE ZONE

Definition: The body of strata between the highest/youngest occurrence of Svalbardella cooksoniae and the highest/youngest occurrence of Areosphaeridium dictyoplokus.

Depth range: 1375-1385 m.

Material: One ditch cutting sample.

Age: Early Oligocene.

Lithostratigaphic unit: Brygge Formation.

Description: The zone contains a relatively rich and diverse marine microflora, with Svalbardella cooksoniae, Deflandrea granulata, Samlandia chalmydophora and Cordosphaeridium gracile being characteristic species (Fig. A13).

Remarks: Manum et al. (1989) found that Svalbardella cooksonia was restricted to their Early Oligocene Chiropteridium lobospinosum Zone in ODP Hole 643 in the Norwegian Sea.

AREOSPHAERIDIUM DICTYOPLOKUS ZONE

Definition: The body of strata between the highest/youngest occurrence of Areosphaeridium dictyoplokus and the highest/youngest occurrence of Heteraulacacysta porosa (Bujak & Mudge 1994).

Depth range: 1385-1410 m.

Material: Three ditch cutting samples.

Age: Late Eocene.

Lithostratigaphic unit: Brygge Formation.

Description: The zone contains a rich and diverse marine microflora. Species having their youngest occurrence in this zone are Areosphaeridium dictyoplokus, Areosphaeridium michoudii and Cordosphaeridium funiculatum. Other characteristic species found in the zone are Cereborycta bartonensis, Homotrybilum tenuispinosum, Enneadocysta pectiniformis, Dracodinium condylos and Thalassiphora delicate (Fig. A13).

Remarks: The last occurrence datum of Areosphaeridium dictyoplokus appears to be a well documented marker of the uppermost Eocene in the North Sea area (Powell 1992, Bujak & Mudge 1994) and the Norwegian-Greenland Sea (Firth, 1996, Mangerud & Charnock, 1999).

DIPHYES COLLIGERUM ZONE

Definition: The body of strata between the highest/youngest occurrence of Diphyes colligerum and the highest/youngest occurrence of abundant Systematophora placacantha (Bujak & Mudge, 1994).

Depth range: 1410 m.

Material: One ditch cutting samples.

Age: Middle Eocene.

Lithostratigaphic unit: Brygge Formation.

Description: The zone contains a rich and diverse marine microflora, which include Areosphaeridium dictyoplokus, Areosphaeridium michoudii, Cereborycta bartonensis, Charlesdownie coleothrypta, Homotrybilum tenuispinosum, Enneadocysta pectiniformis, Thalassiphora delicata and Phthanoperidinium distictum (Fig. A13).

Remarks: The presence of Phthanoperidinium distictum suggest a correlation to Subzone E6b of Bujak & Mudge (1994) dated as Late Lutetian. The present dinoflagellate cyst data suggest that there is a minor hiatus between the Diphyes colligerum Zone and the overlying Areosphaeridium dictyoplokus Zone and that Bartonian strata (correlatable to the H. porosa Zone of Bujak & Mudge (1984)) are missing.

Strontium isotope stratigraphy

One interval from well 6609/11-1 was analysed for strontium isotopes. 34 tests of U. venusta saxonica were picked from the sample at 1260 m. The sample gave a corrected ⁸⁷Sr/⁸⁶Sr-ratio of 0.708968. On the seawater Sr isotope curve of Howarth & McArthur (1997) this ⁸⁷Sr/⁸⁶Sr-ratio corresponds to an age of approximately 6.3 Ma (Table 1, Fig. A12).

Lithology

Upper Pliocene (Naust Formation)

The ditch cutting samples from the Upper Pliocene unit contain a clay-rich diamicton which is also rich in sand, silt and pebbles of mainly crystalline rocks. The pebbles are interpreted as ice-rafted and indicate that the sediments were deposited after the marked increase in the supply of ice-rafted detritus to the Norwegian Sea, which started at about 2.75 Ma (Fronval & Jansen 1996).

Upper Miocene and Upper Miocene to Lower Pliocene (Kai Formation)

The ditch cutting samples from this unit contains mostly fine-grained material. Clay dominates the samples, but the content of sand and silt is also considerable. Some pebbles of crystalline rock are also recorded. The sand is mainly glauconitic, but some quartzose sand is also recorded. Most of the quartzose sand and the pebbles are probably caved.

Lower Oligocene and Lower Miocene (Brygge Formation)

This unit is dominated by clay. Some silt and sand (mainly glauconitic) are also recorded. Some of the sand may be caved from the immediately overlying unit.

Stratigraphy and lithology of well 6508/5-1 on the Nordland Ridge

Well location, material and methods

Well 6508/5-1 (65º42’51.23’’N, 08º28’35.44’’E, Fig. A14) was drilled on the Nordland Ridge and sampled the Kai Formation. A number of 29 ditch cutting samples were analysed for foraminifera, Bolboforma and radiolarians. The same amount of material and the same kind of fossils preparation methods was used for well 6508/5-1 as for wells 6609/11-1, 6407/9-1, 6407/9-2 and 6407/9-5.

Micropalaeontological assemblages

The sections from the Upper Miocene to Late Pliocene contain moderately rich to rich benthic faunas of mainly calcareous foraminifera. Quite sparse planktonic foraminiferal faunas are recorded in the upper part of the Upper Miocene to Upper Pliocene sections. The lower part of the Upper Miocene contains a rich planktonic assemblage of Bolboforma, radiolarian, pyritized diatoms and planktonic foraminifera. The Lower-Middle Eocene section is characterized by a very large population of radiolarian and a sparse population of agglutinated foraminifera.

Benthic foraminiferal assemblages

CIBICIDES GROSSUS ASSEMBLAGE

Definition: The top of the assemblage extends to the uppermost investigated sample (1120 m). The base is marked by the highest/youngest occurrence of E. pygmeus.

Depth range: 1120-1170 m.

Material: Five ditch cutting samples.

Age: Late Pliocene.

Lithostratigraphic unit: Naust Formation.

Correlation: Zone NSB 15 of King (1989), Cibicides grossa zone of Stratlab (1988) and Zone NSR 12 B of Gradstein & Bäckström (1996).

Description: This unit contains a moderately rich benthic fauna of calcareous foraminifera. C. teretis is commen throughout. Other important species include C. grossus, N. affine, E. groenlandicum, B. marginata, A. fluens, B. tenerrima and E. excavatum. E. hannai is recorded in some samples (Fig. A14).

Remarks: The occurrence of C. grossus and E. hannai show that this unit is of Late Pliocene age (Doppert 1980, King 1989).

EPONIDES PYGMEUS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of E. pygmeus. The base is marked by the highest/youngest occurrence of C. telegdi.

Depth range: 1170-1210 m.

Material: Four ditch cutting samples.                                               

Age: Late Miocene to Early Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Probably Cibicides telegdi – Eponides pygmeus – Neogloboquadrina atlantica (dextral) zone of Eidvin et al. (1998a) and probably lower part of Melonis – Trifarina zone of Stratlab (1988).

Description: This unit contains a rich benthic fauna of calcareous foraminifera. N. affine and C. teretis occur most frequently. Other important taxa include E. pygmeus, A. fluens, B. tennerima and Epistominella sp. (Fig. A14).

Remarks: This assemblage is correlated with the E. pygmeus assemblage in well 6407/9-5, 6407/9-1 and 6507/12-1, the E. pygmeus – S. bulloides assemblage in well 6407/9-1 and the E. pygmeus – G. subglobosa assemblage in well 6609/11-1 and is of Late Miocene to Early Pliocene age.

EPONIDES PYGMEUS – CIBICIDES TELEGDI ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of C. telegdi. The base is marked by the highest/youngest occurrence of U. venusta saxonica.

Depth range: 1210-1230 m.

Material: Two ditch cutting samples.

Age: Late Miocene to Early Pliocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Probably Cibicides telegdi – Eponides pygmeus – Neogloboquadrina atlantica (dextral) zone of Eidvin et al. (1998a) and probably lower part of Melonis – Trifarina zone of Stratlab (1988).

Description: This unit contains a rich benthic fauna of calcareous foraminifera. N. affine and C. teretis is both common. Other characteristic forms include E. pygmeus, A. fluens and B. tenerrima (Fig. A14).

Remarks: This assemblage is correlated with the E. pygmeus assemblage in well 6407/9-5, 6407/9-1 and 6507/12-1, the E. pygmeus – S. bulloides assemblage in well 6407/9-1 and the E. pygmeus – G. subglobosa assemblage in well 6609/11-1 and is of Late Miocene to Early Pliocene age.

UVIGERINA VENUSTA SAXONICA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of U. venusta saxonica. The base is marked by the highest/youngest occurrence of M. communis.

Depth range: 1230-1300 m.

Material: Seven ditch cutting samples.

Age: Late Miocene (partly based on Sr. analyses).

Lithostratigraphic unit: Kai Formation.

Correlation: Subzone NSB 13b of King (1989).

Description: Also this unit contains a rich benthic fauna of calcareous foraminifera. U. venusta saxonica and N. affine occur most frequently. Other characteristic forms include C. teretis, P. bulloides, C. dutemplei and G. subglobosa (Fig. A14).

Remarks: According to King (1989) is U. venusta saxonica known from Upper Miocene to Lower Pliocene sediments in the North Sea. Sr. analyses of tests of U. venusta saxonica from 1260 m gave ages of approximately 6.0 and 6.4 Ma (Late Miocene) and consequently rule out an Early Pliocene age.

MARTINOTTIELLA COMMUNIS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of M. communis. The base is marked by the highest/youngest occurrence of S. spectabilis.

Depth range: 1300-1360 m

Material: Six ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Probably Zone FC of Doppert (1980).

Description: This assemblage contains a moderately rich benthic fauna of mainly calcareous foraminifera. It is fewer specimens in this unit than in the overlying units. No specimens are common, but characteristic taxa include N. affine, C. teretis, E. pygmeus, P. bulloides, U. venusta saxonica (upper part), G. subglobosa, M. communis (agglutinated) and E. umbonatus (Fig. A14).

Remarks: M. communis is known from the Middle Miocene to Lower Pliocene of the Netherlands (Doppert 1980) and from the Miocene on the Norwegian continental shelf (Skarbø & Verdenius 1986).

SPIROPLECTAMMINA SPECTABILIS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of S. spectabilis. The base is undefined.

Depth range: 1360-1400 m.

Material: Five ditch cutting samples.

Age: Lower to Middle Eocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Zone NSA 5 of King (1989), Spiroplectammina spectabilis zone of Stratlab (1988) and probably Zone NSR 5A or NSR 5B of Gradstein & Bäckström (1996).

Description: This unit contains a sparse fauna of agglutinated foraminifera. S. spectabilis occurs most frequently. Bathysiphon sp. and Karreriella sp. are also recorded in some samples (Fig. A14).

Remarks: According to King (1989) is S. spectabilis known from the Lower to Middle Eocene in the North Sea area. According to Gradstein & Bäckström (1996) is this species described from upper Palaeocene to Middle Eocene deposits in the North Sea and the Haltenbanken areas.

v

Planktonic fossil assemblages 

NEOGLOBOQUADRINA PACHYDERMA (SINISTRAL) ASSEMBLAGE

Definition: The top of the assemblage extends to the uppermost investigated sample (1120 m). The base is marked by the highest/youngest occurrence of G. bulloides.

Depth range: 1120-1130 m.

Material: One ditch cutting sample.

Age: Late Pliocene (partly based on benthic foraminiferal evidence).

Lithostratigraphic unit: Naust Formation.

Correlation: N. pachyderma (sinistral) Zone of Spiegler & Jansen (1989).

Description: Just a few specimens of unencrusted form of N. pachyderma (sinistral) are recorded in the sole sample which constitutes this unit (Fig. A14).

Remarks: The unencrusted form of N. pachyderma (sinistral) is known from Late Pliocene and Pleistocene sediments in the Norwegian Sea. Pleistocene deposits (younger than approximately 1.8 Ma) is totally dominated by the encrusted form of N. pachyderma (sinistral).

GLOBIGERINA BULLOIDES ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of G. bulloides. The base is marked by the highest/youngest occurrence of N. atlantica (sinistral).

Depth range: 1130-1210 m.

Material: Eight ditch cutting samples.

Age: Late Miocene-Early Pliocene to Late Pliocene.

Lithostratigraphic units: Kai and Naust formations.

Correlation: Globigerina bulloides Zone of Weaver & Clement (1986).

Description: The assemblage is characterized by a sparse fauna of planktonic foraminifera. Characteristic species include G.bulloides, N. pachyderma (sinistral, unencrusted), T. quinqueloba and N. pachyderma (dextral). N. atlantica (dextral) and G. inflate are also recorded in a few samples (Fig. A14).

Remarks: G. bulloides Zone is described from the North Atlantic (DSDP Leg 94) in Miocene to Pliocene sediments as young as 2.2 Ma (Weaver & Clement 1986). On the Vøring Plateau G. bulloides is common in Miocene to Pliocene deposits older than 2.4 Ma (Spiegler & Jansen 1989).

NEOGLOBOQUADRINA ATLANTICA (SINISTRAL)

Definition: The top of the assemblage is taken at the highest/youngest occurrence of N. atlantica (sinistral). The base is marked by the highest/youngest occurrence of B. laevis.

Depth range: 1210-1260 m.

Material: Five ditch cutting samples.

Age: Late Miocene to Late Miocene-Early Pliocene.

Lithostratigraphic unit: Kai Formation.

Correlation: N. atlantica (sinistral) Zone of Weaver & Clement (1986) and Spiegler & Jansen (1989).

Desription: Planktonic foraminifera are also sparse in this unit. Characteristic taxa include N. atlantica (sinistral), G. bulloides and T. quinqueloba. N. pachyderma (dextral), N. atlantica (dextral) and G. glutinata are also recorded in a few samples (Fig. A14).

Remarks: N. atlantica (sinistral) is known from the North Atlantic and the Vøring Plateau in Late Miocene to Late Pliocene sediments (Weaver & Clement 1986, Spiegler & Jansen 1989). A few reworked specimens of B. laevis are recorded in the lowermost sample. 

BOLBOFORMA METZMACHERI ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of B. metzmacheri. The base is marked by the highest/youngest occurrence of B. subfragori and B. fragori.

Depth range: 1260-1300 m.

Material: Four ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Bolboforma metzmacheri Zone of Spiegler & Müller (1992) and Müller & Spiegler (1993), Bolboforma metzmacheri zone of Stratlab (1988), Zone NSR 10 of Gradstein & Bäckström (1996) and Subzone NSP 14b of King (1983).

Description: This unit contains a rich planktonic fossil assemblage of Bolboforma, foraminifera, radiolarian and pyritized diatoms. Radiolarian and pyritized diatoms are dominant, with subordinate Bolboforma and planktonic foraminifera. B. laevis and B. metzmacheri are the most common Bolboforma species. B. clodiusi is also recorded. N. atlantica (dextral) is the most common foraminifera. Other characteristic taxa include G. bulloides, N. atlantica (sinistral) and N. acostaensis (Fig. A14).

Remarks: B. metzmacheri is described from sediments with an age of approximately 10.0-8.7 Ma on the Vøring Plateau (Spiegler & Müller 1992 and Müller & Spiegler 1993).

BOLBOFORMA SUBFRAGORI- BOLBOFORMA FRAGORI ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of B. subfragori and B. fragori. The base is marked by the highest/youngest occurrence of the radiolarian of genius Cenosphaera sp.

Depth range: 1300-1360 m.

Material: Six ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Bolboforma fragori/B. subfragori Zone of Spiegler & Müller (1992) and Müller & Spiegler (1993), Subzone NSP 14a of King (1983) and Bolboforma spiralis zone of Stratlab (1988).

Description: This unit is characterized by a rich planktonic fossil assemblage of radiolarian, pyritized diatoms, Bolboforma and foraminifera. Radiolarian and pyritized diatoms are dominant, with subordinate Bolboforma and planktonic foraminifera. B. subfragori is the most common Bolboforma species. Other important forms include B. fragori and B. laevis. B. clodiusi and B. pseudohystrix are also recorded. Characteristic planktonic foraminifera include G. bulloides, N. atlantica (sinistral), N. atlantica (dextral), G. glutinata and N. acostaensis (upper part, Fig. A14).

Remarks: A B. fragori/B. subfragori Zone is known from deposits with an age of approximately 11.7-10.3 Ma from the North Atlantic and the Vøring Plateau (Spiegler & Müller 1992 and Müller & Spiegler 1993).

CENOSPHAERA SP. ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of radiolarian of genus Cenosphaera sp. The base of the assemblage is undefined.

Depth range: 1360-1400 m.

Material: Five ditch cutting samples.

Age: Lower to Middle Eocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Zone NSP 6 of King (1989).

Description: The greater proportion of the planktonic fossil in this interval is radiolarian including abundant specimens of the genus Cenosphaera. A few pyritized diatoms are recorded in upper part of the unit (Fig. A14).

Remarks: A Cenosphaera sp. acme is known from the Lower to Middle Eocene of the North Sea (King 1989).

Strontium isotope stratigraphy

Two samples from one interval in well 6508/5-1 were analysed for strontium isotopes. Tests of U. venusta saxonica were picked from the interval 1260 m and the samples gave corrected ⁸⁷Sr/⁸⁶Sr-ratos of 0.708991 and 0.708965 corresponding to ages of approximately 6.0 and 6.4 Ma respectively on the seawater Sr isotope curve of Howarth & McArthur (1997, Table 1, Fig. A14).

Lithology

Upper Pliocene (Naust Formation)

The samples from the Upper Pliocene unit contain a clay-rich diamicton with sand, silt and ice-rafted pebbles of mainly crystalline rocks.

Upper Miocene to Lower Pliocene (Kai Formation)

The ditch cutting samples from this interval are mostly fine-grained. Clay dominates the samples, but the content of silt, sand (mainly quartzose) and pebbles of crystalline rocks are also considerable. Most of the sand and the pebbles are probably caved from the Upper Pliocene section.

Upper Miocene (Kai Formation)

The Upper Miocene samples are also mostly fined grained. However, the upper and lower part are rich in glauconitic sand. Some quartzose sand and pebbles of crystalline rocks is recorded in most samples, but these are probably caved.

Lower to Middle Eocene (Brygge Formation)

The samples in the Lower to Middle Eocene unit are dominated by clay. Some silt and sand (mostly glauconitic) are also recorded. A few caved pebbles of crystalline rock are recorded in some samples. 

Stratigraphy and lithology of well 6609/5-1 on the Nordland Ridge

Well location, material and methods

Well 6609/5-1 (66º37’42.73’’N, 09º24’52.17’’E, Fig. 1) was drilled on the Nordland Ridge and sampled the Kai Formation. A number of 37 ditch cutting samples were analysed for foraminifera, Bolboforma and radiolarians. The same amount of material and the same kind of fossils preparation methods we used for well 6609/5-1 as for wells 6508/5-1, 6609/11-1, 6407/9-1, 6407/9-2 and 6407/9-5.

Micopalaeontological assemblages

The Upper Pliocene unit contains a moderately rich benthic fauna of mainly calcareous foraminifera and a sparse planktonic fossil assemblage. The Upper Miocene – Lower Pliocene unit contains sparse both benthic and planktonc assemblages. The Upper Miocene unit contains moderately rich benthic and planktonic faunas, except in the lowermost part with few benthic foraminifera and nearly no planktonic foraminifera and Bolboforma. The Lower – Middle Eocene unit contains a sparse fauna of agglutinated foraminifera and a rich planktonic assemblage of mainly radiolarian. The interval dated to Early Eocene contains a sparse benthic assemblage of both agglutinated and calcareous foraminifera and a rich planktonic assemblage of radiolarian and diatoms.   

Benthic foraminiferal assemblages

CIBICIDES GROSSUS ASSEMBLAGE

Definition: The top of the assemblage extends to the uppermost investigated sample (1500 m). The base is marked by the lowest/oldest consistent occurrence of C. grossus.

Depth range: 1500-1560 m.

Material: Seven ditch cutting samples.

Age: Late Pliocene.

Lithostratigraphic unit: Naust Formation.

Correlation: Zone NSB 15 of King (1989), Cibicides grossa zone of Stratlab (1988) and Zone NSR 12 B of Gradstein & Bäckström (1996).

Description: This interval contains a moderately rich benthic fauna of mainly calcareous foraminifera. C. grossus is common. Other important species include E. groenlandicum, E. albiumbilicatum, B. tenrerrima, E. excavatum, C. teretis and C. scaldiensis  (Fig. A15).

Remarks: The occurrence of C. grossus and E. hannai show that this unit is of Late Pliocene age (Doppert, 1980, King, 1989).

UNDEFINED INTERVAL

Depth range: 1560-1580 m.

Material: One ditch cutting.

Age: Late Miocene to Early Pliocene (partly based on log correlation).

Lithostratigraphic unit: Kai Formation.

Description: The sole sample which constitutes this interval contains a sparse benthic fauna of calcareous foraminifera including E. groenlandicum, N. affine, E. albiumbilicatum, E. excavatum, C. teretis, C. scaldisiensis and C. dutemplei (Fig. A15).

Remarks: Most of the recorded specimens are known from sediment from almost the entire Neogene. The exception is C. dutemplei which is known from the Upper Oligocene to the Lower Pliocene in the Netherlands (Doppert, 1980) and from the Upper Oligocene to the Upper Miocene on the Norwegian continental shelf (Skarbø & Verdenius 1986). However, this species is also recorded in the lowermost part of the overlying unit where it probably is reworked. Reworking may also be the reason for the occurrence in this unit.

GLOBOCASSIDULINA SUBGLOBOSA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of G. subglobosa. The base is marked by the highest/youngest occurrence of U. venusta saxonica.

Depth range: 1580-1600 m.

Material: Two ditch cutting samples.

Age: Late Miocene to Late Miocene-Early Pliocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Probably Zone NSB 12c and 13a of King (1989) and probably G. subglobosa – Ehrenbergina variabilis zone of Stratlab (1988).

Desription: The unit contains a sparse benthic fauna of calcareous foraminifera. No species is common, but characteristic taxa include G. subglobosa, N. affine, E. albiumbilicatun, P. bulloides (lower part), S. bulloides (lower part) and C. telegdi (lower part, Fig. A15).

Remarks: G. subglobosa is recorded from the Oligocene to the Lower Pliocene in the North Sea (Eidvin & Rundberg 2001 and Eidvin & Rundberg this volume). S. bulloides is described from Upper Oligocene to Upper Miocene deposits in the Netherlands (Doppert 1980).

UVIGERINA VENUSTA SAXONICA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of U. venusta saxonica. The base is marked by the highest/youngest occurrence of M. communis.

Depth range: 1600-1680 m.

Material: Eight ditch cutting samples.

Age: Late Miocene (partly based on Sr. analyses and Bolboforma evidence).

Lithostratigraphic unit: Kai Formation.

Correlation: Subzone NSB 13b of King (1989).

Description: This assemblage contains a moderately rich benthic fauna of mainly calcareous foraminifera. Taxa are significantly more numerous in this interval than in the immediately overlying unit. U. venusta saxonica, G. subglobosa and N. affine occur most frequently. Other important species include C. teretis, C. dutemplei, P. bulloides, E. pygmeus and C. telegdi (Fig. A15). 

Remarks: According to King (1989) is U. venusta saxonica known from Upper Miocene to Lower Pliocene sediments in the North Sea area. Sr. analyses of tests of U. venusta saxonica from 1650-1660 m give an age of approximately 9.6 Ma (Late Miocene).

MARTINOTTIELLA COMMUNIS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of M. communis. The base is marked by the highest/youngest occurrence of B. eocenicus.

Depth range: 1680-1740 m.

Material: Six ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Probably Zone FC of Doppert (1980).

Description: It is considerably fewer taxa in this unit than in the immediately overlying interval. The unit contains a sparse benthic fauna of mainly calcareous foraminifera and the lower part of the unit is nearly barren of benthic foraminifera. Characteristic species in the upper part include M. communis (agglutinated), C. dutemplei, C. teretis, G. subglobosa, E. umbonatus and Karreriella sp. (lower part, agglutinated, Fig. A15).

Remarks: M. communis is known from the Middle Miocene to Lower Pliocene of the Netherlands (Doppert 1980).

BATHYSIPHON EOCENICUS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of B. eocenicus. The base is marked by the highest/youngest occurrence of Cibicidoides eocaenus.

Depth range: 1740-1800 m.

Material: Six ditch cutting samples.

Age: Lower to Middle Eocene (partly based on planktonic fossil evidence).

Lithostratigraphic unit: Brygge Formation.

Correlation: Zone NSB 4 and Zone NSA 4 of King (1989).

Description: This interval contains a very sparse benthic fauna of agglutinated foraminifera. B. eocenicus has a consistent occurrence throughout the assemblage. Bathysiphon sp. is also recorded in some samples (Fig. A15).

Remarks: According to King (1989) is B. eocenicus known from the uppermost Lower Eocene to the Lower Miocene in the North Sea area.

CIBICIDOIDES EOCENICUS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of C. eocenicus. The base is marked by the highest/youngest occurrence of Turrilina brevispira.

Depth range: 1800-1810 m.

Material: One ditch cutting sample.

Age: Lower Eocene (partly based on planktonic fossil evidence).

Lithostratigraphic unit: Brygge Formation.

Correlation: Zone NSB 3 of King (1989).

Description: The sole sample which constitutes this interval contains a very sparse benthic fauna of calcareous and agglutinated foraminifera. C. eocenicus is common. Other recorded taxa include Lenticulina spp. (Fig. A15). 

Remarks: According to King (1989) is C. eocenicus known from Lower to Upper Eocene sediments in the North Sea.

TURRILINA BREVISPIRA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of T. brevispira. The base of the assemblage is undefined.

Depth range: 1810-1860 m.

Material: Five ditch cutting samples.

Age: Lower Eocene (partly based on planktonic fossil evidence).

Lithostratigraphic unit: Brygge Formation.

Correlation: Zone NSB 3 of King (1989).

Description: Also this unit contains a very sparse benthic fauna of calcareous and agglutinated foraminifera. Recorded taxa include T. brevispira, Ammodiscus sp. (agglutinated), Pullenia sp. and Elphidium sp. (Fig. A15).

Remarks: According to King (1989) is T. brevispira known from the Lower Eocene to lowermost Middle Eocene in the North Sea area.

Planktonic fossil assemblages

UNDEFINED INTERVAL

Depth range: 1500-1590 m.

Material: Nine ditch cutting samples.

Age: Late Miocene-Lower Pliocene to Late Pliocene (based on benthic foraminiferal evidence).

Lithostratigraphic unit: Kai and Naust Formation.

Description: Planktonic foraminifera are very sparse in this interval. Just a few specimens of G. bulloides, N. pachyderma (dextral) and N. pachyderma (sinistral) are recorded in some samples (Fig. A15).

BOLBOFORMA METZMACHERI ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of B. metzmacheri. The base is marked by the highest/youngest occurrence of B. laevis.

Depth range: 1590-1630 m.

Material: Four ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Bolboforma metzmacheri Zone of Spiegler & Müller (1992) and Müller & Spiegler (1993), Bolboforma metzmacheri zone of Stratlab (1988), Zone NSR 10 of Gradstein & Bäckström (1996) and Subzone NSP 14b of King (1983).

Description: The unit contains a moderately rich planktonic fossil assemblage of Bolboforma, foraminifera, radiolaria and pyritized diatoms. B. metzmacheri is the only recorded Bolboforma. N. atlantica (dextral) occur most frequently of the foraminifera. Other species include G. bulloides, G. glutinata, N. pachyderma (dextral, upper part) and N. atlantica (sinistral, upper part, Fig. A15).

Remarks: B. metzmacheri is described from deposits with an age of approximately 10.0-8.7 Ma on the Vøring Plateau (Spiegler & Müller 1992 and Müller & Spiegler 1993).

BOLBOFORMA LAEVIS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of B. laevis. The base is marked by the highest/youngest occurrence of B. subfragori and B. fragori.

Depth range: 1630-1670 m.

Material: Four ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Bolboforma laevis/Bolboforma capsula Zone of Spiegler & Müller (1992) and Bolboforma laevis Zone of Müller & Spiegler (1993).

Description: The interval contains a moderately rich planktonic fossil assemblage of planktonic foraminifera, Bolboforma, radiolarian and pyritized diatoms. B. laevis is recorded throughout the unit. B. metzmacheri is recorded in the uppermost sample. N. atlantica (dextral) is common. Other characteristic foraminifera include G. bulloides, G. glutinata and N. atlantica (sinistral, Fig. A15).

Remarks: Spiegler & Müller (1992) and Müller & Spiegler (1993) have recorded a B. laevis/B. capsula Zone from the North Atlantic and a B. laevis Zone from the Vøring Plateau. These zones are described from deposits with an age of approximately 10.3-10.0 Ma.

BOLBOFORMA SUBFRAGORI – BOLBOFORMA FRAGORI ASSEMBLAGE

Definition: The top and base of the assemblage is taken at the highest/youngest and lowest/oldest occurrence of B. subfragori and B. fragori.

Depth range: 1670-1700 m.

Material: Four ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Bolboforma fragori/B. subfragori Zone of Spiegler & Müller (1992) and Müller & Spiegler (1993), Subzone NSP 14a of King (1983) and Bolboforma spiralis zone of Stratlab (1988).

Description: The unit contains a moderately rich planktonic fossil assemblage of foraminifera, Bolboforma, radiolarian and pyritized diatoms. B. sufragori, B. fragori and B. laevis occur frequently. B. pseudohystrix and B. clodiusi are also recorded in a few samples. Planktonic foraminifera include G. bulloides, N. atlantica (dextral), N. atlantica (sinistral) and G. glutinata (upper part, Fig. A15).

Remarks: A B. fragori/B. subfragori Zone is known from deposits with an age of approximately 11.7-10.3 Ma from the North Atlantic and the Vøring Plateau (Spiegler & Müller 1992 and Müller & Spiegler 1993).

UNDEFINED INTERVAL

Depth range: 1700-1740 m.

Material: Four ditch cutting samples.

Age: Late Miocene (based on benthic fossil evidence).

Lithostratigraphic unit: Kai Formation.

Description: The unit contains no planktonic foraminifera and Bolboforma. Just some indefinite radiolarian and pyritized diatoms are recorded in some of the samples (Fig. A15).

CENOSPHAERA SP. ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of Cenosphaera sp. The base is marked by the highest/youngest consistent occurrence of Subbotina gr. liniperta.

Depth range: 1740-1800 m.

Material: Six ditch cutting samples.

Age: Lower to Middle Eocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Zone NSP 6 of King (1989) and Caenosphaera spp. Zone of Stratlab (1988).

Description: This interval contains a rich planktonic fossil assemblage of mainly radiolarian including abundant Cenospharea sp. Pyritized diatoms are recorded in some samples and one, probably reworked, specimen of the planktonic foraminifera Subbotina gr. linaperta is also recorded (Fig. A15).

Remarks: A Cenosphaera sp. acme is known from the Lower to Middle Eocene in the North Sea (King 1989).

SUBBOTINA GR. LINAPERTA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest consistent occurrence of Subbotina gr. linaperta. The base is marked by the highest/youngest occurrence of Coscinodiscus sp. 1 (King, 1993).

Depth range: 1800-1820 m.

Material: Two ditch cutting samples.

Age: Lower Eocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Zone NSP 5 of King (1989), Globigerina linaperta zone of Stratlab (1988) and Zone NSR 4 of Gradstein & Bäckström (1996).

Description: The unit contains a rich planktonic fossil assemblage of radiolarian, mainly Cenospharea sp. and planktonic foraminifera of the species Subbotina gr. linaperta. Pyritized diatoms are also recorded in some samples (Fig. A15).

Remarks: Subbotina gr. linaperta is known from Lower Eocene sediments in the North Sea area (King, 1989).

COSCINODISCUS SP. 1 ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of Coscinodiscus sp. 1. The base of the assemblage is undefined.

Depth range: 1820-1860 m.

Material: Five ditch cutting samples.

Age: Lower Eocene (partly based on benthic foraminiferal evidence).

Lithostratigraphic unit: Brygge Formation.

Correlation: Zone NSP 4 of King (1989), Zone NSR 3 of Gradstein & Bäckström (1996) and Coscinodiscus sp. 1 zone of Stratlab (1988).

Desription: The greater proportion of the planktonic fossils from this interval is radiolarian, mainly Cenosphaera sp. Diatoms are also recorded in most samples including Coscinodiscus sp. 1 and Triceratium sp. (Fig. A15).

Remarks: King (1989) employs Coscinodiscus sp. 1 as the nominate taxon for the Upper Paleocene – Lower Eocene Zone NSP 4 of the North Sea.

Strontium isotope stratigraphy

One sample from well 6609/5-1 was analysed for strontium isotopes. Tests of U. venusta saxonica were picked from the interval 1650-1660 m and the sample gave a corrected ⁸⁷Sr/⁸⁶Sr-ratos of 0.708900 corresponding an age of approximately 9.6 Ma on the seawater Sr isotope curve of Howarth & McArthur (1997, Table 1, Fig. A15).

Lithology

Upper Pliocene (Naust Formation)

The ditch cutting samples from the Upper Pliocene interval contain a clay-rich diamicton which is also rich in sand, silt and ice-rafted pebbles of mainly crystalline rocks.

Upper Miocene to Lower Pliocene (Kai Formation)

The samples from this unit contain mostly fined-grained material. Clay dominates the samples, but the content of silt sand (quartzose and glauconitic) and pebbles of crystalline rocks is also considerable. Most of the quartzose sand and all the pebbles are probably caved.  

Lower Eocene to Lower-Middle Eocene (Brygge Formation)

The samples from the Lower Eocene to Lower-Middle Eocene interval is dominated by clay. Some silt is also recorded.

Stratigraphy and lithology of well 6507/12-1 on the Trøndelag Platform.

Well location, material and methods

Well 6507/12-1 (65°07’01.62’’N, 07°42’42.61’’E, Fig.1) was drilled on the Trøndelag Platform and sampled a near complete section of the Kai Formation. A number of 31 ditch cutting samples were analysed for foraminifera, Bolboforma and diatoms. The same amount of material and the same kind of fossil preparation methods were used for well 6507/12-1 as for the wells 6508/5-1, 6609/5-1, 6609/11-1, 6407/9-1, 6407/9-2 and 6407/9-5.

Micropalaeontological assemblages

The sections from the Upper Miocene to Late Pliocene contain moderately rich to rich benthic faunas of mainly calcareous foraminifera. Quite sparse planktonic foraminiferal faunas are recorded in the upper part of the Upper Miocene to Upper Pliocene sections. The lower part of the Upper Miocene contains a rich planktonic assemblage of Bolboforma, radiolarian and planktonic foraminifera. The Middle Miocene unit contain a moderately rich benthic fauna of mainly calcareous foraminifera and a rich planktonic assemblage of radiolarian, pyritized diatoms, Bolboforma and planktonic foraminifera. The fossil assemblages in the Oligocene and Lower Miocene sections are dominated by radiolarian, pyritized diatoms and sponge spicules. Sparse faunas of bentic calcareous foraminifera and some agglutinated and planktonic forms are also recorded in some sections.

Benthic foraminiferal assemblages

ELPHIDIELLA HANNAI ASSEMBLAGE

Definition: The top of the assemblage extends to the uppermost investigated sample (1300 m). The base is marked by the highest/youngest occurrence of E. pygmeus.

Depth range: 1300-1350 m.

Material: Five ditch cutting samples.

Age: Late Pliocene.

Lithostratigraphic unit: Naust Formation.

Correlation: Zone NSB 15 of King (1989), Cibicides grossa zone of Stratlab (1988) and Zone NSR 12 B of Gradstein & Bäckström (1996).

Description: This assemblage contains a moderately rich benthic fauna of mainly calcareous foraminifera. Characteristic taxa include E. excavatum, C. grossus, E. hannai, E. groenlandicum, N.affine, C. lobatulus, B. marginata, C. teretis and E. albiumbilicatum (Fig. A16).

Remarks: The occurrence of E. hannai and C. grossus show that this unit is of Late Pliocene age (Doppert 1980, King 1989).

EPONIDES PYGMEUS ASSEMBLAGE

Definition: The top of the unit is taken at the highest/youngest occurrence of E. pygmeus. The base is marked by the highest/youngest occurrence of C. telegdi.

Depth range: 1350-1370 m.

Material: Two ditch cutting samples.

Age: Late Miocene to Early Pliocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Probably Cibicides telegdi – Eponides pygmeus – Neogloboquadrina atlantica (dextral) zone of Eidvin et al. (1998a) and probably lower part of Melonis – Trifarina zone of Stratlab (1988).

Description: This unit contains a rich benthic fauna of calcareous foraminifera. N. affine and B. marginata are both common. Other important species include E. pygmeus, A. fluens and C. scaldiensis (Fig. A16).

Remarks: This unit is correlated with the E. pygmeus assemblage in well 6407/9-5 and 6407/9-1, the E. pygmeus – S. bulloides assemblage in well 6407/9-1 and the E. pygmeus – G. subglobosa assemblage in well 6609/11-1 and is of Late Miocene to Early Pliocene age.

EPONIDES PYGMEUS – CIBICIDES TELEGDI ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of C. telegdi. The base is marked by the highest/youngest occurrence of U. venusta saxonica.

Depth range: 1370-1410 m.

Material: Four ditch cutting samples.

Age: Late Miocene to Early Pliocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Probably Cibicides telegdi – Eponides pygmeus – Neogloboquadrina atlantica (dextral) zone of Eidvin et al. (1998a) and probably lower part of Melonis – Trifarina zone of Stratlab (1988).

Description: This assemblage contains a rich benthic fauna of mainly calcareous foraminifera. N. affine and C. teretis are both common. Other characteristic taxa include E. pygmeus, C. telegdi, B. marginata, A. fluens and S. schlumbergeri (agglutinated). C. dutemplei and G. sublobosa are also recorded in some samples (Fig. A16).

Remarks: This assemblage is correlated with the E. pygmeus assemblage in well 6407/9-5 and 6407/9-1, the E. pygmeus – S. bulloides assemblage in well 6407/9-1 and the C. telegdi and E. pygmeus – G. subglobosa assemblages in well 6609/11-1. The age is Late Miocene to Early Pliocene.

UVIGERINA VENUSTA SAXONICA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of U. venusta saxonica. The base is marked by the highest/youngest occurrence of M. communis.

Depth range: 1410-1440 m.

Material: Three ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Subzone NSB 13b of King (1989).

Description: This unit contains a rich benthic fauna of calcareous foraminifera. N. affine and C. teretis occur most frequently. Other important forms include U. venusta saxonica, A. fluens, E. pygmeus, C. dutemplei, C. telegdi, G. subglobosa and P. bulloides (Fig. A16).

Remarks: According to King (1989) is U. venusta saxonica known from Upper Miocene to Lower Pliocene sediments in the North Sea. Sr. analyses of tests of U. venusta saxonica from 1430-1450 m gave an age of 10.0 Ma (Late Miocene) and consequently rule out an Early Pliocene age.

MARTINOTTIELLA COMMUNIS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of M. communis. The base is marked by the highest/youngest occurrence of T. gracilis.

Depth range: 1440-1480 m.

Material: Four ditch cutting samples.

Age: Late Miocene (partly based on planktonic fossil evidence).

Lithostratigraphic unit: Kai Formation.

Correlation: Probably Zone FC of Doppert (1980).

Description: This assemblage contains a moderately rich benthic fauna of mainly calcareous foraminifera. N. affine occurs most frequently. Other characteristic species include: M. communis (agglutinated), C. dutemplei, G. subglobosa, U. venusta saxonica, P. bulloides, S. bulloides and E. variabilis (Fig. A16).

Remarks: M. communis is known from the Middle Miocene to Lower Pliocene of the Netherlands (Doppert 1980) and from the Miocene on the Norwegian continental shelf (Skarbø & Verdenius 1986). S. bulloides is described from Upper Oligocene to Upper Miocene deposits in the Netherlands (Doppert 1980).

TRIFARINA GRACILIS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of T. gracilis. The base is marked by the highest/youngest occurrence of T. alsatica.

Depth range: 1480-1550 m.

Material: Seven ditch cutting samples.

Age: Early to Middle Miocene (partly based on planktonic fossil evidence).

Lithostratigraphic unit: Brygge Formation and lowermost part of Kai Formation.

Correlation: Probably Zone NSB 10 and NSB 9 of King (1989) and probably Zone NSR 8B of Gradstein & Bäckström (1996).

Description: This unit contains a moderately rich to sparse benthic fauna of mainly calcareous foraminifera. It is considerably fewer taxa in this unit than in the immediately overlying unit. Important taxa include T. gracilis, T. gracilis var. A, C. dutemplei and P. bulloides. K. siphonella (agglutinated) and B. elongate are also recorded (Fig. A16).

Remarks: According to Skarbø & Verdenius (1986) is T. gracilis known from Lower Oligocene to Lower Miocene deposits, and T. gracilis var. A is known from Upper Oligocene to Lower Miocene sediments on the Norwegian continental shelf. K. siphonella is recorded from the Middle Eocene to the Lower Miocene, and B. elongate is described from the Upper Oligocene to basal Upper Miocene in the North Sea area (King 1989).

TURRILINA ALSATICA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of T. alsatica. The base is taken at the highest/youngest occurrence of R. bulimoides.

Depth range: 1550-1570 m.

Material: Two ditch cutting samples.

Age: Late Oligocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: NSB 8 of King (1989) and probably Zone NSR 8A and upper part of Zone 7B of Gradstein & Bäckström (1996).

Description: This assemblage contains a sparse benthic fauna of mainly calcareous foraminifera. Recorded species include T. alsatica, B. elongate and Spirosigmoilinella sp. (agglutinated, Fig. A16).

Remarks: T. alsatica is known from the Lower Oligocene to the lowermost Lower Miocene succession in the North Sea (King, 1989). According to Gradstein & Bäckström (1996) are this form known from Lower Oligocene to lowermost Upper Oligocene deposits in the same area.

ROTALIATINA BULIMOIDES ASSEMBLAGE

Definition: The top of the unit is taken at the highest/youngest occurrence of R. bulimoides. The base of the unit is not defined.

Depth range: 1570-1600 m (lowermost investigated sample).

Material: Four ditch cutting samples.

Age: Early Oligocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Subzone NSB 7b of King (1989), Rotaliatina bulimoides zone of Stratlab (1988) and probably Zone NSR 7A and lower part of Zone NSR 7B of Gradstein & Bäckström (1996).

Description:  This unit contains a sparse benthic fauna of mainly calcareous foraminifera. C. tenellus occur most frequently. Other recorded taxa include R. bulimoides, B. elongate, G. soldanii girardana (Fig. A16).

Remarks: R. bulimoides is described from the Lower Oligocene to lowermost Upper Oligocene in the North Sea area according to King (1989). According to Gradstein & Bäckström (1996) is this species known from Eocene to Lower Oligocene deposits in the North Sea and the Haltenbanken area. C. tenellus is known from the Oligocene in Belgium (Batjes, 1958).

Planktonic fossil assemblages

UNDEFINED INTERVAL

Depth range: 1300-1320 m.

Material: Two ditch cutting samples.

Age: Late Pliocene (based on benthic foraminiferal evidence).

Description: Just a few unidentified planktonic foraminifera are recorded in this unit (Fig. A16).

NEOGLOBOQUADRINA PACHYDERMA (DEXTRAL) ASSEMBLAGE
Definition: The top of the assemblage is taken at the highest/youngest occurrence of N. pachyderma (dextral). The base is marked by the highest/youngest occurrence of G. bulloides.

Depth range: 1320-1330 m.

Material: One ditch cutting sample.

Age: Late Pliocene.

Lithostratigraphic unit: Naust Formation.

Correlation: N. pachyderma (dextral) Zone of Weaver (1986), Weaver & Clement (1986) and Spiegler & Jansen (1989) and Subzone NSP 16a of King (1989).

Desription: This assemble is characterized by a sparse fauna of planktonic foraminifera. Recorded species include N. pachyderma (sinistral) and N. pachyderma (dextral, Fig. A16).

Remarks: A latest Pliocene N. pachyderma (dextral) Zone is described by King (1989) from the North Sea, by Weaver (1986) and Weaver & Clement (1986) from the North Atlantic (DSDP Leg 94) and by Spiegler & Jansen (1989) from the Vøring Plateau (ODP Leg 104). On the Vøring Plateau the zone is dated to 1.9-1.8 Ma. The zone is characterized by common N. pachyderma (dextral). However, N. pachyderma (dextral) is also recorded, in smaller numbers, in Pleistocene sections in these areas, and is quite numerous in the warmest interglacials of the last 0.5 Ma (Kellogg 1977, Spiegler & Jansen 1989).

GLOBIGERINA BULLOIDES ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of G. bulloides. The base is marked by the highest/youngest occurrence of N. atlantica (sinistral).

Depth range: 1330-1360 m.

Material: Three ditch cutting samples.

Age: Late Miocene-Early Pliocene to Early Pliocene.

Lithostratigraphic unit: Uppermost Kai Formation to lowermost Naust Formation.

Correlation: G. bulloides Zone of Weaver & Clement (1986) and probably upper part of N. atlantica (sinistral) Zone of Weaver & Clement (1986) and Spiegler & Jansen (1989).

Description: Planktonic foraminifera are sparse in this unit. Taxa include G. bulloides, N. pachyderma (dextral) and T. quinqueloba (Fig. A16).

Remarks: G. bulloides Zone is described from the North Atlantic (DSDP Leg 94) in Miocene to Pliocene sediments as young as 2.2 Ma (Weaver & Clement 1986). On the Vøring Plateau G. bulloides is common in Miocene to Pliocene deposits older than 2.4 Ma (Spiegler & Jansen 1989). G. bulloides is also common in the warmest interglacials of the last 0.5 Ma in the North Atlantic (Kellogg 1977).

NEOGLOBOQUADRINA ATLANTICA (SINISTRAL) ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of N. atlantica (sinistral). The base is marked by the highest/youngest occurrence of N. atlantica (dextral).

Depth range: 1360-1410 m.

Material: Five ditch cutting samples.

Age: Late Miocene to Early Pliocene.

Lithostratigraphic unit: Kai Formation.

Correlation: N. atlantica (sinistral) Zone of Weaver & Clement (1986) and Spiegler & Jansen (1989).

Description: The assemblage is characterized by a sparse fauna of planktonic foraminifera. Recorded species include N. atlantica (sinistral), N. pachyderma (dextral), G. bulloides, T. quinqueloba and G. glutinata (Fig. A16).

Remarks: N. atlantica (sinistral) is known from the North Atlantic and the Vøring Plateau in Late Miocene to Late Pliocene sediments (Weaver & Clement 1986, Spiegler & Jansen 1989).

NEOGLOBOQUADRINA ATLANTICA (DEXTRAL) ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of N. atlantica (dextral). The base is marked by the highest/youngest occurrence of B. laevis.

Depth range: 1410-1440 m.

Material: Three ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Lower N. atlantica (dextral) Zone of Spiegler & Jansen (1989) and N. atlantica (dextral)/N. acostaensis Zone of Weaver (1987) and Weaver & Clement (1987).

Description: This unit contains a sparse assemblage of planktonic foraminifera, pyritized diatoms and radiolarian. Recorded planktonic foraminifera include N. atlantica (dextral), N. atlantica (sinistral), G. glutinata and G. bulloides (Fig. A16).

Remarks: Spiegler & Jansen (1989) describe a lower N. atlantica (dextral) Zone from Upper Miocene sediments on the Vøring Plateau, and Weaver (1987) and Weaver & Clement (1987) record a N. atlantica (dextral)/N. acostaensis Zone from Upper Miocene sediments in the North Atlantic (DSDP Leg 94).

BOLBOFORMA LAEVIS ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of B. laevis. The base is marked by the highest/youngest occurrence of B. subfragori.

Depth range: 1440-1450 m.

Material: One ditch cutting sample.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Bolboforma laevis/Bolboforma capsula Zone of Spiegler & Müller (1992) and Bolboforma laevis Zone of Müller & Spiegler (1993).

Description: The sole sample which constitutes this unit contains a sparse fossil assemblage of Bolboforma and planktonic foraminifera. B. laevis is the only Bolboforma species recorded. Recorded foraminifera include G. bulloides, N. atlantica (sinistral), N. atlantica (dextral), T. quinqueloba and G. glutinata (Fig. A16).

Remarks: Spiegler & Müller (1992) and Müller & Spiegler (1993) have recorded a B. laevis/B. capsula Zone from the North Atlantic and a B. laevis Zone from the Vøring Plateau. These zones are described from deposits with an age of approximately 10.3-10.0 Ma.

BOLBOFORMA SUBFRAGORI ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of B. subfragori. The base is marked by the highest/youngest occurrence of B. badenensis and B. reticulata.

Depth range: 1450-1480 m.

Material: Three ditch cutting samples.

Age: Late Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: Bolboforma fragori/B. subfragori Zone of Spiegler & Müller (1992) and Müller & Spiegler (1993), Subzone NSP 14a of King (1983) and Bolboforma spiralis zone of Stratlab (1988).

Description: This unit is characterized by a rich fossil assemblage of radiolarian, pyritized diatoms, Bolboforma and planktonic foraminifera. Radiolarian and pyritized diatoms are dominant, with subordinate Bolboforma and planktonic foraminifera. Recorded Bolboforma include B. subfragori, B. laevis, B. fragori, B. pseudohystrix and B. clodiusi. Recorded planktonic foraminifera include N. atlantica (dextral), N. atlantica (sinistral), G. bulloides, T. quinqueloba and G. glutinata (Fig. A16).

Remarks: A B. fragori/B. subfragori Zone is known from deposits with an age of approximately 11.7-10.3 Ma from the North Atlantic and the Vøring Plateau (Spiegler & Müller 1992 and Müller & Spiegler 1993).

BOLBOFORMA BADENENSIS – BOLBOFORMA RETICULATA ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of B. badenensis and B. reticulate. The base is marked by the highest/youngest occurrence of Diatom sp. 4.

Depth range: 1480-1500 m.

Material: Two ditch cutting samples.

Age: Middle Miocene.

Lithostratigraphic unit: Kai Formation.

Correlation: B. badenensis and B. reticulata zones of Spiegler & Müller (1992), B. badenensis/B. reticulata Zone of Müller & Spiegler (1993) and probably Zone NSP 13 of King (1983).

Description: Also this unit contains a rich fossil assemblage of radiolarian, pyritized diatoms, Bolboforma and planktonic foraminifera. Radiolarian and pyritized diatoms are dominant, with subordinate Bolboforma and planktonic foraminifera. B. reticulata is the most common Bolboforma. Other species include B. badenensis and B. clodiusi. Recorded planktonic foraminifera include N. atlantica (dextral), N. atlantica (sinistral), G. bulloides, G. glutinata and G. zealandica (lower part, Fig. A16).

Remarks: Spiegler & Müller (1992) describe a B. badenensis Zone and a B. reticulata Zone from the North Atlantic and Müller & Spiegler (1993) describe a B. badenensis/B. reticulata Zone from the Vøring Plateau. These zones are recorded from deposits with an age of ca 14-11.9 Ma (Spiegler & Müller, 1992). G. zealandica is known from the Lower to lower Middle Miocene in the North Atlantic (Poore 1979) and in the North Sea (King 1983).

DIATOM SP. 4 – DIATOM SP. 5 ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of Diatom sp. 4. The base is marked by the highest/youngest occurrence of Diatom sp. 3.

Depth range: 1500-1550 m.

Material: Five ditch cutting samples.

Age: Early Miocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Zone NSP 10 of King (1983).

Desciption: This interval contains a rich planktonic fossil assemblage of pyritized diatoms (including Diatom sp. 4 and Diatom sp. 5) and radiolarian. A few caved Bolboforma are also recorded in the upper part of the unit. In this part a few planktonic foraminifera are also recorded. Most of these are also probably caved, but G. zeandica, G. praebulloides and S. disjuncta may be in situ (Fig. A16).

Remarks: G. praebulloides is known from Oligocene to lower Upper Miocene deposits in the North Atlantic (Poore, 1979) and from Oligocene to lower Middle Miocene deposits in the North Sea (Gradstein & Bäckström 1996). S. disjuncta is known from Lower to Middle Miocene deposits in the North Sea (Gradstein & Bäckström 1996). Diatom sp. 4 and Diatom sp. 5 are described from the Lower Miocene in the North Sea (King 1983, 1989). According to King (1989) is Diatom sp. 4 not known from the uppermost part of Lower Miocene and that can indicate that it is a small hiatus between this assemblage and the immediately overlying assemblage.

DIATOM SP. 3 ASSEMBLAGE

Definition: The top of the assemblage is taken at the highest/youngest occurrence of Diatom sp. 3. The base of the assemblage is undefined.

Depth range: 1550-1600 m.

Material: Six ditch cutting samples.

Age: Early Oligocene to Late Oligocene.

Lithostratigraphic unit: Brygge Formation.

Correlation: Subzone NSP 9c of King (1989).

Description: This unit is characterized by a moderately rich planktonic fossil assemblage of radiolarian and pyritized diatoms including Diatom sp. 3 (Fig. A16).

Remarks: Diatom sp. 3 is known from the upper part of Lower Oligocene to the lower part of Lower Miocene in the North Sea area (King, 1989).

Strontium isotope stratigraphy

Three intervals from well 6507/12-1 were analysed for strontium isotopes. Tests of E. variabilis, C. dutemplei and S. bulloides were picked from the samples at 1430-1450 m. This analyse gave a corrected ⁸⁷Sr/⁸⁶Sr-rato of 0.708897. On the seawater Sr isotope curve of Howarth & McArthur (1997) this ⁸⁷Sr/⁸⁶Sr-rato corresponds to an age of approximately 9.7 Ma. Tests of B. fragori, B. subfragori and B. clodiusi from the sample at 1460 m gave a calibrated ⁸⁷Sr/⁸⁶Sr-rato of 0.708931 corresponding to an age of approximately 8.0 Ma. Tests of B. fragori and B. subfragori from the sample at 1470 m gave a calibrated ⁸⁷Sr/⁸⁶Sr-rato of 0.708865 corresponding to an age of approximately 10.9 Ma (Table 1, Fig. A16).

Lithology

Upper Pliocene (Naust Formation)

The ditch cutting samples from the Upper Pliocene unit contain a clay-rich diamicton which is also rich in sand, silt and pebbles of mainly crystalline rocks. The pebbles are interpreted as ice-rafted and indicate that the sediments were deposited after the marked increase in the supply of ice-rafted detritus to the Norwegian Sea, which started at about 2.75 Ma (Fronval & Jansen 1996).

Middle Miocene to Lower Pliocene (Kai Formation)

The ditch cutting samples from this unit contains mostly fine-grained material. Clay dominates the samples, but the content of sand and silt is also considerable. Pebbles of crystalline rock are also recorded. The sand is mainly glauconitic, but quartzose sand is also recorded. Most of the quartzose sand and the pebbles are probably caved.

Lower Oligocene and Lower Miocene (Brygge Formation)

This ditch cutting samples in this unit contain clay, silt and sand (mainly glauconitic).

Appendix 2

Definition of the Molo Formation

Name: Molo is the Norwegian name for jetty.

Well type section: Well 6610/3-1 (Statoil) from approximately 349 m (the top is not sampled and logged in the well) to 555 m (Fig. A9), coordinates 66°55’29.70’’N, 10°54’06.28’’E (Nordland Ridge, Fig. 1).

Well reference section: Well 6407/9-5 (Shell) from 670 to 787 m (Fig. A1), coordinates 64°16’42.35’’N, 07°44’14.66’’E (Trøndelag Platform, Fig. 1).

Thickness: A total thickness of 206 m in the type well is only sampled with five side wall cores (Fig. A9). In the reference well a total thickness of 117 m is sampled with ditch cutting samples at ten meters interval (Fig. A1). Some short vibro cores are sampled in the Nordland Ridge area (Fig. 1). Close to its northern boundary (block 6610/2 and 6610/5) the unit reach more than 500 m (Fig. 1).

Distribution: The formation extends from the cost off Møre at approximately 63º30’N, along the inner Mid Norwegian shelf up to the Nordland Rigde and Lofoten area at approximately 67º40’ N (Fig. 1)

Lithology: The lithology varies considerably throughout its distribution area. In most well and boreholes from proximal parts, the unit consists mainly of red to yellow coloured sand. Some sections also contain well rounded, rust tinted pebbles. In some wells glauconitic sand and mica-rich sand are recorded. In the Draugen Field (Trøndelag Platform), where the distal part is investigated, the unit contains glauconitic sand, silt and clay.

Basal boundary: In the type well the lower boundary is recognised by an abrupt change from greyish clay stone of the Brygge Formation to grey mica-rich sand of the Molo Formation. The boundary is marked by a strong negative spike at approximately 555 m on the gamma log (Fig. A9). In the reference well the lower boundary is recognised by an abrupt change from greyish clay stone of the Brygge Formation to dark (nearly black) glauconitic sand of the Molo Formation. The boundary is further marked by an increase in the gamma ray response and a decrease in velocity (Fig. A1).

Characteristics of the upper boundary: The upper boundary is not sampled and logged in the type well and it is only recognised on seismic lines. In the reference well the upper boundary is recognised by a marked decrease in velocity and a slight decrease in the gamma ray response into the overlying glacio-marine diamicton (Fig. A1). 

Age: Late Miocene – Early Pliocene.

Depositional environment: The formation was deposited in a costal shallow marine to prograding deltaic environment, probably formed in a wave-dominated environment with extensive long-shore drift.

Remarks: It is only in wells from the distal part, including the reference well, that it is possible to date the Molo Formation by means of biostratigraphical and strontium isotope analyses. In wells from the proximal part, including the type well, only reworked fossils are recorded. Most of the sediments in this part are probably reworked from other formations including the Brygge and Tare formations.

The Molo Formation has previously informally been named the “Frøyrygg formation” by Askvik & Rokoengen (1985) and informally introduced as the “Molo formation” by Gustavson & Bugge (1995).

Acknowledgements

The authors extend their thanks to Inger M. Våge, Rune Goa, Finn Moe, Tone M. Tjelta Hansen, Jan Allan Eide and Birgitte Madland at the Norwegian Petroleum Directorate for careful and accurate technical assistance and preparation of illustrations. Yuval Ronen and Ane Birgitte Nødtvedt at the University of Bergen have carried out strontium isotope analyses. Jenö Nagy at the University of Oslo gave advises in identification of Palaeogene foraminifera. We are also grateful to Norwegian Petroleum Directorate, Hydro ASA, the Geological Survey of Norway and Pertra ASA for supporting and funding the project and to Statoil a.s. and A/S Norske Shell for supplying sidewall cores.

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Figures in Appendix

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Fig. A1. Range chart of the most important benthic and planktonic foraminifera, Bolboforma and other planktonic index fossils in the investigated interval of well 6407/9-5. Legend for columns: thin (rare) 0-5 %, middle (common) 5-20 %, thick (abundant) 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units, ms/f = microseconds per foot.

Fig. A2. Range chart of the most important benthic and planktonic foraminifera and other planktonic index fossils in the investigated interval of well 6407/9-2. Legend for columns: thin (rare) 0-5 %, middle (common) 5-20 %, thick (abundant) 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units, ms/f = microseconds per foot.

Fig. A3. Range chart of the most important benthic and planktonic foraminifera and other planktonic index fossils in the investigated interval of well 6407/9-1. Legend for columns: thin (rare) 0-5 %, middle (common) 5-20 %, thick (abundant) 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units, ms/f = microseconds per foot.

Fig. A4. Range chart of the most important dinoflagellate index fossils in the investigated interval of well 6407/9-5. Legend for columns: thin (rare) 0-5 %, middle (common) 5-20 %, thick (abundant) 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units, ms/f = microseconds per foot.

Fig. A5. Range chart of the most important dinoflagellate index fossils in the investigated interval of well 6407/9-2. Legend for columns: thin (rare) 0-5 %, middle (common) 5-20 %, thick (abundant) 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units, ms/f = microseconds per foot.

Fig. A6. Range chart of the most important dinoflagellate index fossils in the investigated interval of well 6407/9-1. Legend for columns: thin (rare) 0-5 %, middle (common) 5-20 %, thick (abundant) 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units, ms/f = microseconds per foot.

Fig. A7. Range chart of the most important foraminiferal and radiolarian index fossils in the investigated interval of well 6510/2-1. Rare = 0-5 %, common = 5-20 %, abundant = 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units.

Fig. A8. Range chart of the most important dinoflagellate index fossils in the investigated interval of well 6510/2-1. Rare = 0-5 %, common = 5-20 %, abundant 20 % = or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units.

Fig. A9. Range chart of the most important dinoflagellate index fossils in the investigated interval of well 6610/3-1. Rare = 0-5 %, common = 5-20 %, abundant 20 % = or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units.

Fig. A10. Range chart of the most important foraminiferal index fossils in the investigated interval of well 6610/2-1S. Legend for columns: thin (rare) 0-5 %, middle (common) 5-20 %, thick (abundant) 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units.

Fig. A11. Range chart of the most dinoflagellate index fossils in the investigated interval of well 6610/2-1S. Legend for columns: thin (rare) 0-5 %, middle (common) 5-20 %, thick (abundant) 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units.

Fig. A12. Range chart of the most important benthic and planktonic foraminifera, Bolboforma  and other planktonic index fossils in the investigated interval of well 6609/11-1. Legend for columns: thin (rare) 0-5 %, middle (common) 5-20 %, thick (abundant) 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units, ms/f = microseconds per foot.

Fig. A13. Range chart of the most important dinoflagellate index fossils in the investigated interval of well 6609/11-1. Legend for columns: thin (rare) 0-5 %, middle (common) 5-20 %, thick (abundant) 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units, ms/f = microseconds per foot.

Fig. A14. Range chart of the most important benthic and planktonic foraminifera, Bolboforma  and other planktonic index fossils in the investigated interval of well 6508/5-1. Legend for columns: thin (rare) 0-5 %, middle (common) 5-20 %, thick (abundant) 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units, ms/f = microseconds per foot.

Fig. A15. Range chart of the most important benthic and planktonic foraminifera, Bolboforma  and other planktonic index fossils in the investigated interval of well 6609/5-1. Legend for columns: thin (rare) 0-5 %, middle (common) 5-20 %, thick (abundant) 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units, ms/f = microseconds per foot.

Fig. A16. Range chart of the most important benthic and planktonic foraminifera, Bolboforma  and other planktonic index fossils in the investigated interval of well 6507/12-1. Legend for columns: thin (rare) 0-5 %, middle (common) 5-20 %, thick (abundant) 20 % or more. M RKB = meters below rig floor, m MSL = metres below mean sea level, gAPI = American Petroleum Institute gamma ray units, ms/f = microseconds per foot.