Utsira Formation

Nordland Group, Kai Formation


English / Norwegian

Utsira Formation / Utsiraformasjonen

Derivatio nominis

Named by Deegan & Scull (1977) after the Utsira High.

Original definition

Deegan, C. E. & Scull, B. J. 1977. A standard lithologic nomenclaturefor the Central and Northern North Sea. Institute of Geological Sciences Report 77/25, Norwegian Petroleum Directorate Bulletin 1, 33 pp.


The formation consists of dominantly thick, blocky marine sandstones with thinner intercalated claystones. The sandstones are clear to white, often lightly greenish; normally very fine to fine-grained, but locally medium to coarse-grained. Rock fragments and lignite are occasionally present, while glauconite and fossil fragments are common throughout. Soft, plastic, light greenish claystones and siltstones separate the sandstone beds.

The Utsira Formation shows a complex depositional architecture (see depositional environment), which varies with latitude. In the southern Viking Graben, around 58° N, Utsira Formation forms a giant mounded sand system pinching out both eastward and westward. Only scattered thin mudstone intervals are present in the blocky sands. Here the base of the sands erodes into the underlying sequence (Rundberg & Eidvin, 2005).

At 59° N, in the vicinity of the type well, the Utsira Formation is characterized by a lower part of dominantly blocky sands forming the main sandbody, and an upper part displaying a clear coarsening upwards trend.

In the northern Viking Graben, around 60°- 61° N, the Utsira Formation forms a large mounded sandbody consisting of predominantly blocky sands with only subordinate thin mudstone intervals. Towards its northernmost extent (Tampen area) the Utsira Formation is present only as a thin unit of glauconitic sand.


Where the Utsira Formation forms a giant mounded sandbody maximum thicknesses are attained. Around 58° N in the southern Viking Graben, the total thickness reaches 250- 300 m. At 60°- 61° N in the northern Viking Graben the sandbody reaches a thickness of almost 200 m in the basin centre. Here the main sandbody thins out westwards. In the central Viking Graben the Utsira Formation is distinctly thinner. Around 59° N, where the Utsira Formation comprises a distinct lower and an upper subunit, thinner sands of 25-100 m occur. Here the lower subunit is thickest towards the east, while the upper subunit clearly thins in an eastward direction.

Rundberg & Eidvin (in press) have shown that previous maximum thicknesses published were exaggerated due to an error in the original definition of the Utsira and Skade formations.

Geographical distribution

The Utsira Formation forms an elongated sandy system approximately 450 km long and 90 km wide. The depocenter is located in the centre of the northern North Sea (Viking Graben). The formation is present in the Viking Graben from about 58° N to the Tampen Spur (61°N), with a north-eastern pinchout between the Oseberg and Troll Fields.

Type well

Well name


Logs from well 16/1-1 (pdf)


WGS84 coordinates: 58°59'17.65" N, 02°01'58.29" E.
UTM coordinates: 6539294.92 N - 444415.00 E
UTM zone: 31

Drilling operator name

Esso Exploration and Production Norway A/S

Completion date


Interval of type section (m)

In the type well the formation extends from 644.5 m to 820 m below KB (Rundberg & Eidvin, 2005). Originally Deegan & Scull (1977) defined the formation to cover the interval from 644.5 m to 1064 m below KB.

Thickness in type well (m)

The formation reaches 175 m in the type well (Rundberg & Eidvin, 2005). Previously the Utsira Formation was defined to be 419,5 m in the type well (Deegan & Scull 1977).

Reference well

Well name


Logs from well 15/9-13 (pdf)


WGS84 coordinates: 58°22'25.96" N, 01°56'02.86" E.
UTM coordinates: 6470978.02 N - 437653.70 E
UTM zone: 31

Drilling operator name

Den norske stats oljeselskap a.s (STATOIL)

Completion date


Interval of reference section (m)

In the reference well the formation spans the interval from xxx m to yyy m below KB (Rundberg & Eidvin in press). The reference section was previously defined to be 57 m to 847 m below KB (Deegan & Scull 1977), but then included the upper parts of the Skade Formation (Deegan & Scull 1977).


Lower boundary (basal stratotype)

The lower boundary of the Utsira Formation is usually identified by an abrupt decrease in gamma-ray response from the underlying claystones into the sandstones of the Utsira Formation. In wells where the Utsira Formation directly overlies the Skade Formation the transition may be identified by a break on the velocity log. The Utsira Formation overlies Lower Miocene and Oligocene strata to the north and Middle Miocene strata to the south. Towards its northernmost extent (Tampen area) the Utsira Formation is present only as a thin glauconitic sand unit overlying Oligocene strata. This unit is believed to continue southwards where it caps the main Utsira Formation (Rundberg 1989). In the southern Viking Graben the base of the Utsira Formation is coincident with an erosive unconformity. This is not the case further north.

Upper boundary in type well section

The top of the sands is marked by an abrupt increase in gamma-log response.

Fossil events/zones dating the formation

The first published biostratigraphic analysis of the samples taken by Esso in the 16/1-1 type well of the Utsira Formation interval was undertaken by Gradstein et al. (1992, 1994), and Gradstein & Bäckström (1996). The authors did not consider the well in terms of its lithostratigraphic subdivision. From 1250-2090 ft (378-633m) were observed Elphidium spp., Cassidulina teretis, C.islandica, and Cibicidoides grossus, from 2090 to 2110 ft (633-639m) Sigmoilopsis schlumbergeri, Neogloboquadrina pachyderma and Globorotalia inflata, and from 2110-2385 ft (639-723 m) Neogloboquadrina atlantica, Martinotiella cylindrica, Globorotalia crassaformsis, and G. puncticulata. These observations indicate the presence from 378-633 m of Upper Pliocene strata, from 633 to 639m lower part of Upper Pliocene, and from 639 to 723 m lower Pliocene beds. Based on these data, the Utsira Formation in 16/1-1 is Early Pliocene in age. Below 818m the well encountered an assemblage belonging in the upper part of the G. ex gr. praescitula zealandica Zone, early Middle Miocene. Thus indicates a hiatus at the base of the Utsira Formation in the type well, with at least part of Middle Miocene and all of Upper Miocene strata absent.

A detailed re-study of original sample material in the type well was undertaken by E. Anthonissen (Anthonissen 2004, MsC thesis). The observations below are directly taken from this study (see range chart of figure ????.).


Definition: The top of the assemblage is undefined as it extends to the uppermost investigated sample. The base is defined by the last occurrence of Neogloboquadrina atlantica (sinistral).

Depth range: ?689-698 m

Material: One ditch cutting sample

Age: early Late Pliocene

Lithostratigraphy: Clayey sand-mudstone; micaceous with common fossil fragments, green glauconite present, subrounded quartz (Source: original Esso well-log)

Correlation: Subassemblage NSR12A of Gradstein & Bäckström (1996) and (upper) Neogloboquadrina atlantica (dextral) Assemblage of Spiegler & Jansen (1989).

In situ assemblage: This assemblage contains a fairly rich benthic foraminiferal assemblage, with Planulina ariminensis and Cibicidoides grossus being the most abundant taxa. Other characteristic forms include Cibicides lobatulus. No agglutinated forms occur. Planktic foraminifera are present in much lower abundance with Neogloboquadrina pachyderma (dextral), Neogloboquadrina pachyderma (sinistral), and Neogloboquadrina atlantica (dextral) present. The radiolarian Cenosphaera sp. is also present.

Reworked or caved assemblage: Abundant Bulimina marginata are believed to be caved from overlying Pleistocene material. Late Miocene reworking is evident in the presence of Uvigerina venusta saxonica, Uvigerina venusta deurnensis and Glomospira charoides (all with last occurrences in Late Miocene).


Definition: The top of the assemblage is defined by the last occurrence of Globigerina bulloides and the last common occurrence of Neogloboquadrina atlantica (sinistral). The base of the assemblage is undefined as it extends to the lowermost investigated sample.

Depth range: 707-762? m

Material: Four ditch cutting samples

Age: Early Pliocene

Lithostratigraphy: (707-725 m) Clayey sand-mudstone; micaceous with common fossil fragments, green glauconite present, subrounded quartz.
(744-762 m) Sand, greenish-gray, micaceous with some glauconite and common fossil fragments, subrounded-rounded quartz.

Correlation: N.atlantica (sinistral) Assemblage of Spiegler & Jansen (1989) and Assemblage NSR11 of Gradstein & Bäckström (1996).

In situ assemblage: Abundant Melonis affinis, abundant Cibicidoides grossus, abundant Uvigerina venusta deurnensis, rare Pullenia bulloides. Approximately half of the assemblage comprises lagenids, including Nodosaria (Dentalina) koninckii.

The agglutinated forms are represented by rare to common Sigmoilopsis schlumbergeri together with the presence of Textularia decrescens and Siphotextularia sculpturata.

Planktic formaminifera are present in much greater abundance and diversity than in the overlying assemblage (although this may be an expression of small sample size in the overlying assemblage). Neogloboquadrina atlantica (sinistral) is common to abundant, Globigerina bulloides is rare to common, Globorotalia inflata is rare, Neogloboquadrina pachyderma (sinistral) is present. Other characteristic taxa present are Orbulina suturalis, Orbulina universa, Globoquadrina altispira globosa, Neogloboquadrina dutertrei, and Catapsydrax sp.

Reworked or caved assemblage: Abundant and millimeter-large Lenticulina rotulata, equally large and abraded fish otoliths and sponge fragments suggest downslope transport from the inner shelf. Broken individual Spiroplectammina carina var. deperdita, Martinottiella cylindrica and Asterigerina guerichi guerichi specimens suggest Miocene reworking, the presence of Karreriella bradyi suggests Late Oligocene reworking, while even older reworking is evident in the presence of Cretaceous Inoceramus fragments. Caving is minimal.

Using all of above data indicates the Utsira Formation in the type well to be largely Early Pliocene in age, just extending in early Late Pliocene.

The detailed study by Piasecki et al. (2002) using dinoflagellate cysts in seven core samples from the 15/9A-23 well indicate an age of Early Pliocene to early Late Pliocene age for the Utsira sands, with the taxon Invertocysta lacrymosa in the two uppermost Utsira samples and Cyst Type 1 of Vernal & Mudie and Reculatosphaera actinocoronata below.

Head et al. (2004) studied a set of core samples between 906.0 and 913.10m in well 15/9A-11, situated closely above the Utsira sands used by Statoil for carbon dioxide re-injection and storage. Foraminifera indicate the interval to belong in the Cibicidoides grossus Zone, cited above. A brief occurrence of Neogloboquadrina atlantica (dextral) and Cibicidoides pachyderma, observed in older Pliocene strata further north along the Norwegian continental margin, is noted at 913.0m, and interpretated as a relatively warm interval assigned an early Gelasian (late Late Pliocene) age . The cool-tolerant dinoflagellates Filisphaera filifera and Habibacysta tectata indicate a late Late Pliocene, late Gelasian age for the level at 906m. This new information indicates strata immediately overlying the Utsira sands to be Late Pliocene in age, in good agreement with studies cited above.

Based on extensive foraminiferal correlations and direct Sr-isotope dating, Eidvin & Rundberg (2001) concluded that main sand deposition, i.e. the Utsira Formation started after 12 Ma. This is based on the observation that at or just below the very base of the Utsira sands in well 24/12-1 occurs an assemblage with Bolboforma badenensis and B.reticulata of Middle Miocene age, and the presence slightly higher in that well of B.fragori of Late Miocene age, and dated by Sr/Sr to be 10.3-11.7 Ma old (see also Table 2 in Rundberg&Eidvin, 2005). The upper level of the Utsira Formation the authors assign a 5 Ma age, which appears too old in the face of the dinoflagellate and foraminiferal evidence presented above.


The formation is of Late Miocene to early Late Pliocene age. In the type section 16/1-1 the formation is Early Pliocene to early Late Pliocene in age. At the northern limits of the Utsira Formation the upper prograding subunit is of Early Pliocene age and the lower subunit is of Late Miocene age. Further south, where the Utsira Formation is developed as a thick, uniform sand throughout. Here the lower half is of Late Miocene age while the upper half is dated as Early Pliocene.

Rundberg & Eidvin (2005) explain that an error was made in defining the Skade and Utsira formations, in that the Skade Formation, as defined in its type well, correlates to the lower part of the Utsira Formation as defined in its type well. This error was also in conflict with the common usage of the Utsira Formation, as being part of the Nordland Group.

Depositional environment

The Utsira Formation was deposited in a stable, fully marine environment, comprising of shelf sand transport and accumulation within an epeiric sea. The site of deposition was characterized by a combination of strong marine currents and a slow, but continual, sand supply from the eastward-prograding East Shetland Platform (Isaksen & Tonstad 1989; Galloway 2002; Rundberg & Eidvin, 2005). Galloway (2002) interpreted it to be a linked depostional systems tract that included four principal depositional systems: the Shetland Strandplain, the Viking Strait, and the north and south Viking shelf shoals. This depositional model involved sediment dispersal occurring axially in a coast-to-shelf bypass, together with regional basin-centered transport and deposition in the Viking Graben narrow seaway. The environment is interpreted as a high-energy regime with focused flow of oceanic currents through a narrow strait that was also the depocenter. Very low rates of sediment supply and accumulation, explain the high degree of sediment reworking and the presence of abundant autochthonous sediment (e.g. glauconite). Maximum water-depth was between 200-300 m. Diverse fossil faunas suggest widespread, well-mixed, shallow to deep neritic marine conditions prevailed within the North Sea Basin throughout deposition of the Utsira Formation.


Galloway (2002) interpreted the time-equivalent Hutton sands in UK waters to represent a westward prograding strandplain which contributed to sediment supply in the Viking Strait.

The Utsira Formation is time-equivalent with the Molo Formation distributed off Mid-Norway (Eidvin et al. in press).


Anthonissen, E. D. 2003. Neogene foraminiferal biostratigraphy of the 16/1-1 and 29/3-1 wells (North Sea Basin) and implications for regional correlations. M.Sc. Thesis, University College London, UK (unpublished).

Deegan, C.E. and Scull, B.J. 1977. A standard lithostratigraphic nomenclature for the central and northern North Sea, in Institute of Geological Sciences Report, NPD Bulletin X. 35pp.

Eidvin, T. and Rundberg, Y. 2001. Late Cainozoic stratigraphy of the Tampen area (Snorre and Visund fields) in the northern North Sea, with emphasis on the chronology of early Neogene sands. Norsk Geologisk Tidsskrift 81, 119-160.

Galloway, W. E. 2002. Palaeogeographic setting and depositional architecture of a sand- dominated shelf depositional system, Miocene Utsira Formation, North Sea Basin.

Gradstein, F.M. and Bäckström, S., 1996. Cainozoic biostratigraphy and paleobathymetry, northern North Sea and Haltenbanken. Norsk Geologisk Tidsskrift, 76(1), 3-32.

Gradstein, F.M., Kaminski, M.A., Berggren, W.A., Kristiansen, I.L. and D'Ioro, M.A., 1994. Cenozoic biostratigraphy of the North Sea and Labrador Shelf. Micropaleontology 40, 1-152. Head, M. J., Riding, J. B., Eidvin, T., Chadwick, R. A.2004. Palynological and foraminiferal biostratigraphy of (Upper Pliocene) Nordland Group mudstones at Sleipner, northern North Sea. Marine and Petroleum Geology 21: 277-297.

Isaksen, D. and Tonstad, K. 1989. A revised Cretaceous and Tertiary lithostratigraphic nomenclature for the Norwegian North Sea. NPD Bulletin 5, 59 pp.

Piasecki, S., Gregersen, U. & Johannessen, P. 2002. Lower Pliocene dinoflagellate cysts from cored Utsira Formation in the Viking Graben, northern North Sea. Marine and Petroleum Geology 19, 55-67.

Rundberg, Y. 1989. Tertiary sedimentary history and basin evolution of the University Trondheim (Reprinted 1991: Geol. Inst. Report Series 25, NTH, 292pp).

Rundberg, Y. & Eidvin, T. 2005. Controls on depositional history and architecture of the Oligocene-Miocene succession, northern North Sea Basin. In: Onshore-Offshore Relationships on the North Atlantic Margin (eds.: B.T.G. Wandås et al.), Norwegian Petroleum Society Special Publications, 12: 207-239.

Spiegler, D., and Jansen, E. 1989. Planktonic foraminiferal biostratigraphy of Norwegian Sea sediments: ODP Leg 104. In: Eldholm, O. et al. (eds.),Proceedings of the Ocean Drilling Program, Scientific Results, 104: 681-696.

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