BILLEFJORDEN GROUP (CP-01)

STATUS OF UNIT: Formal
FIRST USE OF NAME: Cutbill & Challinor 1965
CURRENT DEFINITION: Cutbill & Challinor 1965
SYNONYM(S) AND REFERENCE(S): "Culm sandstones": Nathorst 1910
ORIGIN OF NAME: Billefjorden: A fiord in central Spitsbergen, a bifurcation of Isfjorden
TYPE AREA: Area between Billefjorden and Austfjorden, Dickson Land, central Spitsbergen
STRUCTURAL SETTING: Late Palaeozoic platform of Svalbard and the Barents Sea Shelf; in Svalbard widely preserved in middle Carboniferous troughs
DEPOSITIONAL AGE: Famennian - Viséan
OVERLYING UNIT(S): Gipsdalen Group; locally on Sørkapp-Hornsund High: Sassendalen Group
UNDERLYING UNIT(S): Andrée Land Group (Devonian), Pre-Old Red
SUPERIOR UNIT: None

Fig. 2-11
Fig. 2-11: A fault block with Devonian and unconformably overlying Carboniferous strata (left) displaced against Devonian (right) at Triungen (northwestern Dickson Land). Carboniferous strata include Hørbyebreen and Mumien formations (light and grey), Hultberget Formation (upper red band) and Wordiekammen Formation (uppermost cliff). Photo: W.K. Dallmann

OTHER USE OF NAME: Billefjorden Fault Zone (Harland et al. 1974). Billefjorden Trough (Gjelberg & Steel 1981)
THICKNESS: Up to 2500 m (cumulative)
MAIN LITHOLOGIES: Sandstone, shale, conglomerate
DESCRIPTION: Clastic sediments with local coal seams, bound to a number of tectonic depressions developed subsequent to the deposition of Old Red sediments. The group comprises the Hørbyebreen and Mumien formations of the Billefjorden–Ny Friesland area, the Orustdalen and Vegardfjella formations of western Spitsbergen, the Adriabukta, Hornsundneset and Sergeijevfjellet formations of the Sørkapp-Hornsund area, the Røedvika and Nordkapp formations of Bjørnøya and time/facies equivalents of the Barents Sea Shelf.

Fig. 2-12
Fig. 2-12: Typical sediments of the Billefjorden Group at Billefjorden, representing delta plain and overbank deposits. Photo: E.P. Johannessen


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HØRBYEBREEN FORMATION (CP-02)

DISTRIBUTION: shown on Fig. 2-09
STATUS OF UNIT: Formal
FIRST USE OF NAME: Cutbill & Challinor 1965
CURRENT DEFINITION: Cutbill et al. 1976
SYNONYM(S) AND REFERENCE(S): None
ORIGIN OF NAME: Hørbyebreen: A glacier tongue ending in the inner part of Billefjorden, central Spitsbergen
TYPE SECTION (Fig. 2-15): Stratotype: Ferdinandbreen, Dickson Land
STRUCTURAL SETTING: Early Carboniferous basin in central and northern Spitsbergen, plunging southward below younger strata; mainly preserved in the middle Carboniferous Billefjorden Trough
DEPOSITIONAL AGE: Famennian - Viséan
DATING METHOD: Palynology


Fig. 2-13
Fig. 2-13: The Russian coal mining settlement Pyramiden (recently abandoned) with transportation facilities to the mine in the mountain side. The coal seams occur in the Hørbyebreen and Mumien formations in a fault block displaced against the strata in the mountain Pyramiden (background). The mountain side shows the Ebbadalen Formation with the red-coloured conglomerates of the Odellfjellet Member, overlying sandstones of the Minkinfjellet Formation, and limestones of the Wordiekammen Formation (uppermost cliff). Photo: J. Nagy

REFERENCE(S) FOR AGE: Playford 1962, 1963; Nøttvedt et al. 1992; Vigran 1994 (unpubl.)
OVERLYING UNIT(S): Mumien Formation
UNDERLYING UNIT(S): Andrée Land Group, Pre-Old Red
SUPERIOR UNIT: Billefjorden Group
OTHER USE OF NAME: None
THICKNESS: Up to 200 m, >140 m in stratotype
MAIN LITHOLOGIES: Sandstone, conglomerate, coal
LOWER BOUNDARY DEFINITION: Angular unconformity, with greyish sandstones or conglomerates overlying folded basement strata or folded or tilted sediments of the Devonian Wood Bay or Mimerdalen formations
DESCRIPTION: The Hørbyebreen Formation occurs between Dicksonfjorden and Nordenskiöldbreen, with good exposures in the Billefjorden Trough between Billefjorden and Austfjorden. The formation is also present in Ny Friesland forming a few down-faulted outliers along the western margin of the Ny Friesland Block.
The lower part of the formation (Triungen Member) is poorly exposed in the eastern part of Dickson Land but locally well exposed in western Dickson Land (Fig. 2-11). The Triungen Member rests unconformably on Devonian strata in the western part of Dickson Land and on Pre-Old Red in the east. It consists of sandstones and conglomerates of fluvial origin, with interbedded lacustrine and flood-basin shales.

Fig. 2-14
Fig. 2-14: Sigillaria stems are common in the deposits of the Billefjorden Group; here at Lemstrømfjellet (southwestern Ny Friesland). Photo: W.K. Dallmann

The upper part of the formation (Hoelbreen Member) consists mainly of black/grey shales and mudstones, interbedded with thin sandstones, coals, coaly shales and horizons of clay ironstones, representing flood plain to flood basin deposits (Fig. 2-12). Sigillaria stems occur frequently (Fig. 2-14).
Palynological studies indicate that there is a stratigraphic break between the Triungen and te Hoelbreen Member (P. van Veen, pers. comm. 1989; Nøttvedt et al. 1992). According to Playford (1962, 1963) two different assemblages of palynomorphs are present within the formation. The transition between the two assemblages occurs within the Hoelbreen Mb. and is not marked by lithological changes (Cutbill et al. 1976).

Fig. 2-15
Fig. 2-15: Stratigraphic section CP-02/04 Stratotype for: Hørbyebreen Formation, Hoelbreen Member Locality: Ferdinandbreen (Mumien NE) Reference: Gjelberg, J.G. (unpubl.)


Triungen Member (CP-03)
STATUS OF UNIT: Formal
FIRST USE OF NAME: Cutbill & Challinor 1965
CURRENT DEFINITION: Cutbill et al. 1976
SYNONYM(S) AND REFERENCE(S): None
ORIGIN OF NAME: Triungen (Norw. from "Mt. Triplex"): A mountain in NW Dickson Land
TYPE SECTION (Fig. 2-18): Stratotype: Triungen West, Dickson Land
DEPOSITIONAL AGE: Famennian


Fig. 2-16
Fig. 2-16: Gravelstones and crossbedded sandstones in the basal part of the Triungen Member on Ålen (Dickson Land). Photo: W.K. Dallmann


DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Playford 1962, 1963; Kaiser 1970, 1971; Vigran 1994 (unpubl.); Veen, P. van (unpubl. data)
OVERLYING UNIT(S): Hoelbreen Member
UNDERLYING UNIT(S): Andrée Land Group, Pre-Old Red
SUPERIOR UNIT: Hørbyebreen Formation
OTHER USE OF NAME: Triungen-Grønhorgdalen Fault Zone Triungen Fault (McCann & Dallmann 1996)
THICKNESS: 130 m in stratotype
MAIN LITHOLOGIES: Sandstone, conglomerate, shale
LOWER BOUNDARY DEFINITION: See Hørbyebreen Formation
DESCRIPTION: The Triungen Member consists mainly of grey sandstones and conglomerates (Fig. 2-16, Fig. 2-17).

Fig. 2-17
Fig. 2-17: Alluvial fan deposits with reworked, light sandstone in the Triungen Member on Faraofjellet (Dickson Land). Photo: E.P. Johannessen

There are, however, some thick units of grey/greyish purple shale, interbedded with thin sandstones, in the type section at Triungen. It is also reported that fine-grained sediments are relatively common at other localities, though poorly exposed. The member probably represents fluvial and lacustrine depositional environments.

Fig. 2-18
Fig. 2-18: Stratigraphic section CP-03 Stratotype for: Triungen Member Locality: Triungen W Reference: Gjelberg, J.G. (unpubl.)

Palynological material studied by Playford (1962, 1963), and reinterpreted by P. van Veen (unpubl.) and Vigran 1994 (unpubl.), suggests an upper Devonian (Famennian) age of the member, corresponding in age with the Røedvika Fm. on Bjørnøya (based on comparisons with studies by Kaiser 1970, 1971 on Bjørnøya). There may be a stratigraphic break between the Triungen Member and the overlying Hoelbreen Member of Tournaisian age (P. van Veen, pers. comm. 1996; Vigran, 1994, unpubl.).

Hoelbreen Member (CP-04)
STATUS OF UNIT: Formal
FIRST USE OF NAME: Cutbill & Challinor 1965
CURRENT DEFINITION: Cutbill et al. 1976
SYNONYM(S) AND REFERENCE(S): None
ORIGIN OF NAME: Hoelbreen: A glacier in Dickson Land, NW of Billefjorden
TYPE SECTION (Fig. 2-15): Stratotype: Ferdinandbreen, Dickson Land The stratotype was originally defined at the northwestern slope of Birger Johnsonfjellet (Cutbill & Challinor 1965), but no documentation is available.
DEPOSITIONAL AGE: Tournaisian - Viséan
DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Playford 1962, 1963; Nøttvedt et al. 1992; Vigran 1994 (unpubl.)
OVERLYING UNIT(S): Mumien Formation
UNDERLYING UNIT(S): Triungen Member
SUPERIOR UNIT: Hørbyebreen Formation
OTHER USE OF NAME: None
THICKNESS: Up to 150 m, 110 m in stratotype
MAIN LITHOLOGIES: Shale, sandstone, coal
LOWER BOUNDARY DEFINITION: The lower boundary is defined at the onset of a shale-dominated succession above the sandstones of the Triungen Member.
DESCRIPTION: The Hoelbreen Member consists generally of black to grey shales and mudstones with thinly interbedded ripple-laminated sandstones, coals and clay ironstones (siderite). Interbedded thin sandstones (2-50 cm) and thin mudstones are common lithological associations and may form up to several metre thick units. Only a few prominent sandstone units (3-5m thick) occur within the member. These sandstones represent fluvial channels. Coal seams occur at several levels; the thickest seams are located in the uppermost part of the member in the Pyramiden area. The member reflects deposition on flood plains and in flood basins with associated meandering and ribbon channels.
Coal from the Hoelbreen Member is mined at the Russian mining community of Pyramiden (Fig. 2-13). The mine is situated in a narrow tectonic block between two strands of the Billefjorden Fault Zone, in the mountains Pyramiden and Mumien.

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MUMIEN FORMATION (CP-05)

DISTRIBUTION shown on Fig. 2-09
STATUS OF UNIT: Formal
FIRST USE OF NAME: Here
CURRENT DEFINITION: Here
SYNONYM(S) AND REFERENCE(S): The Mumien Formation comprises most of the "Svenbreen Formation" (Cutbill & Challinor 1965), though excluding the "Hultberget Member".
ORIGIN OF NAME: Mumien (transl. "The Mummy"): A mountain in northeastern Dickson Land
TYPE SECTION (Fig. 2-19): Stratotype: Northern slope of Birger Johnsonfjellet, Dickson Land
STRUCTURAL SETTING: Early Carboniferous basin in central and northern Spitsbergen, plunging southward below younger strata; mainly preserved in the middle Carboniferous Billefjorden Trough
DEPOSITIONAL AGE: Viséan
DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Nøttvedt et al. 1992; Vigran 1994 (unpubl.); Veen, P. van (unpubl.)
OVERLYING UNIT(S): Hultberget Formation; locally in the Billefjorden Fault Zone: Ebbadalen Formation, Wordiekammen Formation
UNDERLYING UNIT(S): Hørbyebreen Formation; Pre-Old Red
SUPERIOR UNIT: Billefjorden Group
OTHER USE OF NAME: None
THICKNESS: Up to 100 m, 95 m in stratotype
MAIN LITHOLOGIES: Sandstone, shale, coal
LOWER BOUNDARY DEFINITION: The base of the formation is defined at the base of the prominent sandstones of the Sporehøgda Member (see below), which overlie various lithologies of the Hoelbreen Member. The boundary is easy to recognise within the Billefjorden Fault Zone. It is less distinct on the eastern side of Austfjorden and in central Dickson Land, where the sandstones of the Sporehøgda Mb. are less prominent and frequently interbedded with shales.
Cutbill and Challinor (1965) discussed the boundary between the Hørbyebreen Formation and the overlying Sporehøgda Member and suggested that it represents a slight angular unconformity. Palaeocurrent studies indicate a possible change at this boundary from a northern to a southern drainage direction (Aakvik 1981; Gjelberg 1984), supporting the assumption of an unconformity between the Hørbyebreen and Mumien formations. There is, however, no palaeontological or palynological evidence for an unconformity that might involve a detectable period of non-deposition or erosion (Playford 1962, 1963; Vigran 1994, unpubl.). Available palaeocurrent data consist of very few measurements and may be statistically insignificant.

Fig. 2-19
Fig. 2-19: Stratigraphic section CP-05/06/07. Stratotype for: Mumien Formation, Sporehøgda and Birger Johnsonfjellet members. Locality: Birger Johnsonfjellet N. Reference: Gjelberg 1984 (unpubl.)


DESCRIPTION: The Mumien Formation consists of a lower, relatively thick sandstone interval and alternating black and grey shales and coals in the upper part. It is divided into two members, the Sporehøgda Member and the Birger Johnsonfjellet Member.
The Sporehøgda Member comprises the sandstone-dominated lower part of the formation. The overlying prominent coal-bearing shales are defined as the Birger Johnsonfjellet Member. The formation onlaps Pre-Old Red eastwards on the Ny Friesland Block. The sandstones of the Sporehøgda Member represent fluvial channel deposits with braided or meandering streams (Aakvik 1981, unpubl.; Gjelberg 1984, unpubl.). The Birger Johnsonfjellet Member reflects a lacustrine/flood basin depositional environment.
Most of the coal seams are cannel coals rich in Botryococcus algae. The coals are derived from a sapropelic lacustrine environment (Abdullah et al. 1988). Coals are mined at the Russian mining community of Pyramiden (see Hørbyebreen Formation).

Sporehøgda Member (CP-06)
STATUS OF UNIT: Formal
FIRST USE OF NAME: Cutbill & Challinor 1965
CURRENT DEFINITION: Cutbill et al. 1976
SYNONYM(S) AND REFERENCE(S): None
ORIGIN OF NAME: Sporehøgda (transl. "The Spur Hill"): A mountain in northern Bünsow Land
TYPE SECTION (Fig. 2-19): Stratotype: Ferdinandbreen, Dickson Land
DEPOSITIONAL AGE: Viséan
DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Nøttvedt et al. 1992; Vigran 1994 (unpubl.); Veen, P. van (unpubl.)
OVERLYING UNIT(S): Birger Johnsonfjellet Mb.
UNDERLYING UNIT(S): Hoelbreen Member; Pre-Old Red
SUPERIOR UNIT: Mumien Formation
OTHER USE OF NAME: None
THICKNESS: Up to 90 m, 45 m in stratotype
MAIN LITHOLOGIES: Sandstone, shale
LOWER BOUNDARY DEFINITION: See Mumien Formation
DESCRIPTION: The Sporehøgda Member contains several superimposed, metre- to ten-metre-scale, trough cross-stratified sandstone units. Individual units show slight gradation, and are often bounded by curved erosion surfaces. Several metres thick units of fine-grained material are preserved between sandstone sequences, especially in the northern part of the area. Plant fossils, mainly preserved as carbonaceous films and trunk casts or trunk impressions are common.
The member represents mainly braided stream deposits (Gjelberg & Steel 1981; Aakvik 1981, unpubl.).
The member is 30-40 m thick along the Billefjorden Fault Zone west of Petuniabukta, but increases to more than 90 m northwards to Lemstrømfjellet. It pinches out eastwards above Pre-Old Red rocks on the Ny Friesland Platform.

Birger Johnsonfjellet Member (CP-07)
STATUS OF UNIT: Formal
FIRST USE OF NAME: Here; after Gjelberg 1984 (unpubl.)
CURRENT DEFINITION: Here; after Gjelberg 1984 (unpubl.)
SYNONYM(S) AND REFERENCE(S): None
ORIGIN OF NAME: Birger Johnsonfjellet: A mountain in NE Dickson Land
TYPE SECTION (
Fig. 2-19): Stratotype: Birger Johnsonfjellet, Dickson Land
DEPOSITIONAL AGE: Viséan
DATING METHOD: Palynolgy
REFERENCE(S) FOR AGE: Playford 1962, 1963; Nøttvedt et al. 1992; Vigran 1994 (unpubl.); Veen, P. van (unpubl.)
OVERLYING UNIT(S): Hultberget Formation; in easternmost exposures: Minkinfjellet Formation; locally in the Billefjorden Fault Zone: Ebbadalen Formation, Wordiekammen Formation
UNDERLYING UNIT(S): Sporehøgda Member
SUPERIOR UNIT: Mumien Formation
OTHER USE OF NAME: None
THICKNESS: Up to 55 m, 51 m in stratotype
MAIN LITHOLOGIES: Shale, siltstone, coal
LOWER BOUNDARY DEFINITION: The lower boundary is defined where a shale-dominated succession overlies the sandstones of the Sporehøgda Member.
DESCRIPTION: The Birger Johnsonfjellet Member consists mainly of black/grey shales, coaly shales and dark grey claystones, interbedded with thin siltstones (siderite bands) and coal. Plant root horizons are common, especially in the lower part of the member. Most of the coal seams are made up of algal material (Botryococcus) and may represent good source rocks for oil and gas (Abdullah et al. 1988). The member represents mainly flood-basin and lake deposits and becomes more flood-plain dominated eastwards.
The member is 50 m thick on Birger Johnsonfjellet and 55 m at the west side of Elsabreen. It seems to be restricted to the area around the Billefjorden Fault Zone in the Dickson Land area.

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ORUSTDALEN FORMATION (CP-08)

DISTRIBUTION shown on Fig. 2-07, Fig. 2-08
STATUS OF UNIT: Formal
FIRST USE OF NAME: Cutbill & Challinor 1965
CURRENT DEFINITION: Cutbill & Challinor 1965
SYNONYM(S) AND REFERENCE(S): None
ORIGIN OF NAME: Orustdalen: A valley in western Nordenskiöld Land, Western Spitsbergen
TYPE SECTION (Fig. 2-21): The base of the section is not exposed. The previously defined stratotype at Orustdalen (Cutbill & Challinor 1965) is not logged. Hypostratotype: Diabasbukta, Bellsund. Both sections are tectonically disturbed (Braathen & Bergh 1995).
STRUCTURAL SETTING: Early Carboniferous basin in western Spitsbergen; connection with other coeval basins not documented
DEPOSITIONAL AGE: ?Tournaisian - Viséan (?Serpukhovian)
DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Cutbill & Challinor 1965; Fairchild 1982
OVERLYING UNIT(S): Brøggertinden Formation, Vegardfjella Formation, Treskelodden Formation
UNDERLYING UNIT(S): Pre-Old Red
SUPERIOR UNIT: Billefjorden Group
OTHER USE OF NAME: None
THICKNESS: Up to >700 m
MAIN LITHOLOGIES: Sandstone, shale
LOWER BOUNDARY DEFINITION: The lower boundary is an angular unconformity, with greyish sandstones, shales or conglomerates overlying folded Pre-Old Red basement.
DESCRIPTION: The Orustdalen Formation is exposed in western Spitsbergen from Brøggerhalvøya in the north to Hornsund in the south. The formation is mainly composed of a complex stack of fining-upward units of different scale and thickness (Gjelberg 1984, unpubl.). These units often start with cross-stratified (planar and trough) pebbly sandstones and conglomerates and terminate in relatively thin shales. The facies associations indicate a braided stream and flood-plain fines origin.
Gjelberg (1984, unpubl.) concluded that the Orustdalen Formation consists only of continental deposits in the central and southern parts of Spitsbergen. Marginal marine influence in the formation has been suggested by Fairchild (1982), who identified some tidal influence in sediments assigned to the Orustdalen Formation on Brøggerhalvøya, and by Dallmann et al. (1990), who locally observed tidal bundles south of Bellsund (Fig. 2-20).

Fig. 2-20
Fig. 2-20. Cross-bedded, light grey sandstones with tidal bundles occur frequently in the Orustdalen Formation, here at Bellsund. Photo: W.K. Dallmann.


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VEGARDFJELLA FORMATION (CP-09)

DISTRIBUTION shown on Fig. 2-07, Fig. 2-08
STATUS OF UNIT: Formal
FIRST USE OF NAME: Dineley 1958
CURRENT DEFINITION: Cutbill & Challinor 1965
SYNONYM(S) AND REFERENCE(S): "Vegard Sandstone Formation", "Vegard Formation": The above mentioned authors did not use the complete place name.
ORIGIN OF NAME: Vegardfjella: A mountain complex at St. Jonsfjorden, Oscar II Land, Western Spitsbergen
TYPE SECTION (Fig. 2-21): The base of the section is not exposed. The suggested stratotype at Vegardfjella (Dineley 1958) is not logged. Cutbill & Challinor's (1965) revised type locality at Orustdalen is not documented. Until further documentation is provided, SKS does not decide which stratotype should be valid.
Hypostratotype: Diabasbukta, Bellsund


Fig. 2-21
Fig. 2-21: Stratigraphic section CP-08/09 Hypostratotype for: Orustdalen and Vegardfjella formations. Locality: Diabasbukta. Reference: Gjelberg 1984 (unpubl.)


STRUCTURAL SETTING: Early Carboniferous basin in western Spitsbergen; connection with other coeval basins not documented
DEPOSITIONAL AGE: Viséan
DATING METHOD: Palynology in adjacent units
REFERENCE(S) FOR AGE: see Orustdalen Formation
OVERLYING UNIT(S): Brøggertinden Formation, Petrellskaret Formation, Wordiekammen Formation
UNDERLYING UNIT(S): Orustdalen Formation
SUPERIOR UNIT: Billefjorden Group
OTHER USE OF NAME: None
THICKNESS: Up to >150 m. The suggested type section of Dineley (1958) in Orustdalen was reported to be 358 m thick. This interval also includes the redbeds of the overlying Petrellskaret Formation (Cutbill & Challinor 1965).
MAIN LITHOLOGIES: Mudstone, sandstone, coaly shale
LOWER BOUNDARY DEFINITION: The base of the formation is defined where the thick sandstones of the Orustdalen Formation transitionally grade upwards into the heterolithic, finer-grained sediments which dominate the Vegardfjella Formation.
DESCRIPTION: The Vegardfjella Formation ("Vegard Sandstone Formation") was first named by Dineley (1958), who described "thinly bedded, pinkish, quartzose sandstones and thin shales". It was redefined by Cutbill & Challinor (1965).
The formation consists mainly of grey/dark grey shales, interstratified with grey sandstones. Some of the sandstone intervals are relatively thick, particularly in the St. Jonsfjorden area, where both fining- and coarsening-upward trends are present. In the Bellsund area (here defined as the type area), the formation consists mainly of rhythmic alternations of thin sandstones and thin shales, representing thinly bedded turbidites (Gjelberg 1984, unpubl.). The uppermost part of the formation at Bellsund consists of a thick coarsening upward sandstone unit.
The formation represents mainly flood plain and lacustrine deposits in the St. Jonsfjorden area, and mainly lacustrine turbidites in the Bellsund area (Gjelberg 1984, unpubl.).

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ADRIABUKTA FORMATION (CP-10)

DISTRIBUTION shown on Fig. 2-06
STATUS OF UNIT: Formal
FIRST USE OF NAME: Birkenmajer & Turnau 1962; rank revised to 'formation' by Cutbill & Challinor (1965)
CURRENT DEFINITION: Dallmann et al. 1993
SYNONYM(S) AND REFERENCE(S): None
ORIGIN OF NAME: Adriabukta: A bay in the Hornsund fiord, southern Spitsbergen
TYPE SECTION (Fig. 2-22): Stratotype: Adriabukta (coastal section), Hornsund


Fig. 2-22
Fig. 2-22: Stratigraphic section CP-10/13. Stratotype for: Adriabukta Formation, Meranfjellet Member. Locality: Adriabukta. Reference: Gjelberg 1984 (unpubl.)


STRUCTURAL SETTING: Early Carboniferous (?) basin in southern Spitsbergen, preserved in Samarinbreen Syncline
DEPOSITIONAL AGE: Viséan, and/or possibly older: The Early Carboniferous age is based on only two samples with spore specimens of doubtful age-indicative value; a late Devonian age cannot be totally ruled out as yet.
DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Birkenmajer & Turnau 1962
OVERLYING UNIT(S): Hyrnefjellet Formation, Hornsundneset Formation
UNDERLYING UNIT(S): Marietoppen Formation, Pre-Old Red
SUPERIOR UNIT: Billefjorden Group
OTHER USE OF NAME: None
THICKNESS: Up to 1750 m cumulative
MAIN LITHOLOGIES: Shale, sandstone, conglomerate
LOWER BOUNDARY DEFINITION: The lower boundary of the Adriabukta Formation in Sørkapp Land is placed at a distinct erosional unconformity over Caledonian folded basement. Its boundary with Devonian deposits is only exposed north of Hornsund, (Adriabukta) where it is apparently conformable. In the type section, the base is defined by an organic-rich black shale which overlies multicoloured Devonian shales and sandstones.
DESCRIPTION: The basal black shale (see above) is overlain by grey sandstones and conglomerates (Julhøgda Member). Exceptionally, at the mountain Haitanna, thick conglomerates (Haitanna Member) form the base of the formation above crystalline basement. The upper part of the formation consists of a dark, shale-dominated succession (Meranfjellet Member). The upper boundary is defined by the unconformity towards the overlying red conglomerates of the middle Carboniferous Hyrnefjellet Formation north of Hornsund and, south of the fiord, by the tectonised boundary towards massive sandstones of the Hornsundneset Formation.
The formation occurs from the type area north of Hornsund to Guilbaudtoppen in the south, mostly on the eastern flank of the Samarinbreen Syncline. Steel & Worsley (1984) mention an isolated exposure of possible Adriabukta Formation lithologies at Van Keulenfjorden, south of Reinodden, but there are no biostratigraphic data that would be needed to confirm this possible correlation.
The local appearance of the thick and very proximal deltaic or alluvial fan facies of the Haitanna Member suggests that the assumed boundary fault of the sedimentary basin of the Adriabukta Formation (Steel & Worsley 1984) was active during sedimentation and is situated close to Haitanna. The upward development from alluvial through deltaic to an increasingly restricted basin facies, as well as the apparent gradual onlap towards the northwest suggest that the Adriabukta Formation represents the infill of a narrow graben or half-graben which was initiated by Svalbardian block tectonics. The Adriabukta Formation was folded prior to the middle Carboniferous (?"Adriabukta event").

Haitanna Member (CP-11)
STATUS OF UNIT: Formal
FIRST USE OF NAME: Dallmann 1992
CURRENT DEFINITION: Dallmann et al. 1993
SYNONYM(S) AND REFERENCE(S): None
ORIGIN OF NAME: Haitanna (transl. "The Shark Tooth"): A mountain in central Sørkapp Land, southern Spitsbergen
TYPE LOCALITY: Haitanna, Sørkapp Land
DEPOSITIONAL AGE: Viséan or older (see Adriabukta Formation)
DATING METHOD: Palynology in adjacent units
REFERENCE(S) FOR AGE: Birkenmajer & Turnau 1962
OVERLYING UNIT(S): Julhøgda Member
UNDERLYING UNIT(S): Pre-Old Red
SUPERIOR UNIT: Adriabukta Formation
OTHER USE OF NAME: None
THICKNESS: ca. 450 m
MAIN LITHOLOGIES: Conglomerate
LOWER BOUNDARY DEFINITION: See Adriabukta Formation
DESCRIPTION: The Haitanna Member forms the lower, conglomeratic part of the Adriabukta Formation, occurring only locally on the mountain Haitanna, where it constitutes the middle part of the massif and the summit (Fig. 2-23). It can be traced laterally for 2.3 km. It unconformably overlies ?Mid-Proterozoic garnet mica schists.

Fig. 2-23
Fig. 2-23: The occurrence of thick alluvial fan conglomerates of the Haitanna Member is restricted to the mountain Haitanna ("The Shark Tooth"), central Sørkapp Land. Photo: W.K. Dallmann


The conglomerates are texturally and compositionally immature and clast-supported, with up to metre-sized clasts derived from the underlying basement. The member can be subdivided into several thick lobes of probable alluvial fan origin.

Julhøgda Member (CP-12)
STATUS OF UNIT: Formal
FIRST USE OF NAME: Dallmann et al. 1993
CURRENT DEFINITION: Dallmann et al. 1993
SYNONYM(S) AND REFERENCE(S): None
ORIGIN OF NAME: Julhøgda (transl. "Christmas Peak"): A mountain at the Hornsund fiord in northern Sørkapp Land, southern Spitsbergen
TYPE LOCALITY: JulhøgdaHaitanna, Sørkapp Land
DEPOSITIONAL AGE: Viséan or older (see Adriabukta Formation)
DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Birkenmajer & Turnau 1962
OVERLYING UNIT(S): Meranfjellet Member
UNDERLYING UNIT(S): Haitanna Member, Pre-Old Red
SUPERIOR UNIT: Adriabukta Formation
OTHER USE OF NAME: None
THICKNESS: Up to 700 m
MAIN LITHOLOGIES: Sandstone, conglomerate
LOWER BOUNDARY DEFINITION: Where situated above basement, see Adriabukta Formation. Where the Haitanna Member is present, the base of the Julhøgda Member is defined by the first dominance of sandstones above the Haitanna conglomerates.
DESCRIPTION: The Julhøgda Member forms the middle part of the Adriabukta Formation. It consists mainly of sandstones with subordinate conglomerates and shales.
Approx. 700 m thickness are exposed at Haitanna and Guilbaudtoppen, where it conformably overlies the Haitanna Member. At Julhøgda and Pinsetoppen it unconformably overlies folded, ?Middle Proterozoic basement and is still more than 100 m thick (Fig. 2-24), while only 40-50 m are preserved in Adriabukta (N of Hornsund). The composition of the sandstones is macroscopically identical with the matrix of the conglomerates of the other members.

Fig. 2-24
Fig. 2-24: Sandstones of the Julhøgda Member unconformably overlie Precambrian basement at Pinsetoppen (northern Sørkapp Land). The sandstones occur in the lower part of the slope and dip slightly steeper than the slope towards the observer. Photo: W.K. Dallmann


The sandstones are characteristically light to dark grey weathering, dark grey, tight, medium- to fine-grained and often current or trough cross-stratified. They are texturally and compositionally immature with angular grains and abundant detrital micas. The conglomerate intercalations show a texture and composition similar to the Haitanna Member, but are only observed to be max. 1 m thick, polymict, and contain pebbles and boulders of basement lithologies, mostly quartzites, mica schists and marbles of the underlying basement. The matrix is coarse sand to grit. Plant imprints are common.

Meranfjellet Member (CP-13)
STATUS OF UNIT: Formal
FIRST USE OF NAME: Dallmann et al. 1993
CURRENT DEFINITION: Dallmann et al. 1993
SYNONYM(S) AND REFERENCE(S): None
ORIGIN OF NAME: Meranfjellet: A mountain near the Hornsund fiord in northern Sørkapp Land, southern Spitsbergen
TYPE SECTION (Fig. 2-22): Stratotype: Adriabukta (coastal section), Hornsund
DEPOSITIONAL AGE: Viséan or older (see Adriabukta Formation)
DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Birkenmajer & Turnau 1962
OVERLYING UNIT(S): Hyrnefjellet Formation, Hornsundneset Formation
UNDERLYING UNIT(S): Julhøgda Member
SUPERIOR UNIT: Adriabukta Formation
OTHER USE OF NAME: None
THICKNESS: 300-600 m
MAIN LITHOLOGIES: Shale, siltstone, sandstone
LOWER BOUNDARY DEFINITION: The lower boundary of the Meranfjellet Member is defined where a dark siltstone- and shale-dominated succession overlies dark, but light weathering quartzitic sandstones and coarse conglomerates of the Julhøgda Member.
DESCRIPTION: The Meranfjellet Member consists of dark or silty shales and siltstones with subordinate sandstones and conglomerates, similar to those of the Julhøgda Member. The thickness is ca. 300 m in the type section at Adriabukta, but a more complete development (ca. 600 m) with a higher amount of sandstone intercalations has been observed at Meranfjellet. Due to intense folding and thrusting of the Meranfjellet exposures, the internal stratigraphic succession is uncertain, and the indicated thickness values are very rough.
The succession starts above dark, light weathering, quartzitic sandstone and coarse conglomerates or breccias of the Julhøgda Member in Adventpasset: 1. black shale (a few metres); 2. alternating silty shales, dark grey sandstones and thin, dark conglomerate and breccia (150-200 m); 3. dark to medium grey, platy sandstones alternating with subordinate silty shales (100-150 m); 4. dark silty shales (250-300 m). Plant imprints are common.

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HORNSUNDNESET FORMATION (CP-14)

DISTRIBUTION shown on Fig. 2-06
STATUS OF UNIT: Formal
FIRST USE OF NAME: Siedlecki 1960; rank revised to 'formation' by Cutbill & Challinor (1965)
CURRENT DEFINITION: Birkenmajer 1979
SYNONYM(S) AND REFERENCE(S) "Hornsundneset Beds": Siedlecki 1960
ORIGIN OF NAME: Hornsundneset (transl. "Horn Sound Point": The coastal plain forming the NW tip of Sørkapp Land (type area)
TYPE SECTION (Fig. 2-25): Stratotype: Hohenlohefjellet, east of Hornsundneset, Sørkapp Land. The base of the formation is not exposed in this section, but in Andvika a little further to the NNE.

Fig. 2-25
Fig. 2-25: Stratigraphic section CP-14. Stratotype for: Hornsundneset Formation. Locality: Hohenlohefjellet. Reference: Wendorff 1985


STRUCTURAL SETTING: Early Carboniferous basin in southern Spitsbergen; connection with other coeval basins not documented
DEPOSITIONAL AGE: Viséan
DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Siedlecki & Turnau 1964
OVERLYING UNIT(S): Sergeijevfjellet Formation, Hyrnefjellet Formation. Vardebukta Formation
UNDERLYING UNIT(S): Adriabukta Formation, Pre-Old Red
SUPERIOR UNIT: Billefjorden Group
OTHER USE OF NAME: None
THICKNESS: 700-1100 m, 370 m in stratotype
MAIN LITHOLOGIES: Sandstone
LOWER BOUNDARY DEFINITION: Angular unconformity either above folded rocks of the Pre-Old Red or above the dark shales of the Adriabukta Formation (?"Adriabukta event"). The base of the Hornsundneset formation in the Hornsundneset area is commonly defined by a thin quartz conglomerate.
DESCRIPTION: The Hornsundneset Formation occurs in two different areas and structural regimes in Sørkapp Land: (1) gently inclined, overlying the Caledonian basement in the Hornsundneset area, and (2) steeply inclined to overturned within the foldbelt between Bladegga and Gråtinden. Other, minor occurrences are suggested underlying folded Permian strata at øyrlandsodden and Sørkappøya. The Hornsundneset Formation of the Hornsundneset area has been described by De Geer (in Nathorst 1910), Orvin (1940), Siedlecki 1960, Birkenmajer (1964, 1979a), Haczewski (1984), Liparski & C´miel (1984) and Wendorff (1985). Detailed stratigraphic investigations were published by Siedlecki (1960) and Wendorff (1985).
The base of the formation in the Hornsundneset area is commonly defined by a thin quartz conglomerate. The prevailing rocks are medium- to fine-grained, light grey sandstones with darker (or even black) siltstone intercalations. The sandstones locally contain pebble or gravel horizons with quartz clasts. Large-scale, tabular cross-bedding is common, while trough cross-bedding is observed at several stratigraphic levels. Erosional channels up to 1.5 m in depth have been reported. In the lower part of the formation, plant detritus and occasionally rootlets occur, usually in finegrained (silty) beds. The succession shows an overall, though irregular, fining-upward trend.
Knowledge of the formation in the foldbelt area is restricted to rough surveying. There are prevailing massive, light sandstones, occasionally with minor siltstone horizons. Plant remains are very common, and large tree trunks have been observed. A major, coarse quartz or quartzite conglomerate strikes along the north-eastern ridge of Austernebba, 300-350 m above the formation base, where it is ca. 50 m thick, southward to Gråtinden, where it is much closer to the base of the formation. Thin coaly shales occasionally occur within the light grey sandstones, for instance in the summit area at Stuptinden.
Thickness values vary significantly and probably reach 700-750 m at Hornsundneset and 1100 m at Austernebba and Knattberget in the foldbelt.
The depositional environment of the Hornsundneset Formation is interpreted as braided, quickly migrating channels and sand bars, though with an unexpected lack of overbank fines and in situ vegetation (Birkenmajer 1979a; Haczewski 1984; Wendorff 1985).
The Hornsundneset Formation is a possible equivalent to the Orustdalen Formation in Western Spitsbergen.

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SERGEIJEVFJELLET FORMATION (CP-15)

DISTRIBUTION shown on
Fig. 2-06
STATUS OF UNIT: Formal
FIRST USE OF NAME: Siedlecki 1960; rank revised to 'formation' by Cutbill & Challinor (1965)
CURRENT DEFINITION: Siedlecki 1960
SYNONYM(S) AND REFERENCE(S): "Sergeijevfjellet Beds": Siedlecki 1960
ORIGIN OF NAME: Sergeijevfjellet: A mountain to the east of Hornsundneset, NW Sørkapp Land (type locality)
TYPE SECTION (Fig. 2-26): Stratotype: Sergeijevfjellet, E of Hornsundneset, S Spitsbergen.
STRUCTURAL SETTING: Early Carboniferous basin in southern Spitsbergen; connection with other coeval basins not documented

Fig. 2-26
Fig. 2-26: Stratigraphic section CP-15. Stratotype for: Sergeijevfjellet Formation. Locality: Sergeijevfjellet. Reference: Gjelberg 1984 (unpubl.)


DEPOSITIONAL AGE: Viséan
DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Siedlecki & Turnau 1964
OVERLYING UNIT(S): Vardebukta Formation, locally ?Hyrnefjellet Fm.
UNDERLYING UNIT(S): Hornsundneset Formation
SUPERIOR UNIT: Billefjorden Group
OTHER USE OF NAME: None
THICKNESS: Up to 260 m, 160 m in stratotype
MAIN LITHOLOGIES: Sandstone, shale
LOWER BOUNDARY DEFINITION: The base of the formation is defined above the tick sandstones of the Hornsundneset Formation, at the base of the first fining-upward sandstone unit that ends up with a distinct shale interval. On Hohenlohefjellet, the base is situated above a thick coal seam.
DESCRIPTION: The Sergeijevfjellet Formation forms the upper, shale-rich part of the Billefjorden Group in the Hornsund area. The formation occurs exclusively in the Hornsundneset area (Hohenlohefjellet, Sergeijevfjellet, Lisbetdalen) and is cut by the sub-Triassic unconformity. Thin developments through basal parts of the unit are possibly preserved in the Austjøkulen-Kronglebreen area within the Cenozoic foldbelt segment of Sørkapp Land. The formation has been described by Siedlecki (1960), Birkenmajer (1964), Liparski & ´ Cmiel (1984) and Wendorff (1985).
The Sergeijevfjellet Formation consists of medium- to fine-grained, light grey, cross-bedded sandstones, interbedded with a high portion of shales and siltstones. Wavy and lenticular laminations occur frequently. Two thin levels of coal and coaly shale occur. Carbonised plant detritus, leaves and tree ?trunks, as well as trails and burrows, are common within the fine-grained deposits. The maximum observed thickness is 260m.
The sedimentary environment is interpreted to be braided rivers and floodplains (Wendorff 1985).
The Sergeijevfjellet Formation is a possible equivalent to the Vegardfjella Formation in Western Spitsbergen.

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RØEDVIKA FORMATION (CP-16)

DISTRIBUTION shown on Fig. 2-05
STATUS OF UNIT: Formal
FIRST USE OF NAME: Cutbill & Challinor 1965
CURRENT DEFINITION: Cutbill & Challinor 1965
SYNONYM(S) AND REFERENCE(S): "Ursa Sandstone", lower part: Holtedahl 1920
ORIGIN OF NAME: Røedvika: A bay on the E coast of Bjørnøya (type area)
TYPE SECTION (Fig. 2-28): Composite section from localities along the E coast of Bjørnøya; see individual members (C-17,18,19)
STRUCTURAL SETTING: Early Carboniferous basin of the Western Barents Sea Shelf
DEPOSITIONAL AGE: Famennian - Tournaisian
DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Kaiser 1970; Worsley & Edwards 1976; Vigran 1994 (unpubl.)
OVERLYING UNIT(S): Nordkapp Formation, locally Kapp Hanna or Hambergfjellet formations.
UNDERLYING UNIT(S): Pre-Old Red
SUPERIOR UNIT: Billefjorden Group
OTHER USE OF NAME: None
THICKNESS: 120-360 m
MAIN LITHOLOGIES: Sandstone, shale, coal
LOWER BOUNDARY DEFINITION: The base of the formation is defined by the onset of clastic sediments, normally sandstones, above the main Caledonian angular unconformity and the erosive boundary with underlying folded or tilted rocks of the Pre-Old Red.
DESCRIPTION: The Røedvika Formation represents the lower part of the Ursa Sandstone of earlier investigators. A detailed description was published by Horn & Orvin (1928). Worsley & Edwards (1976) subdivided the formation into the Vesalstranda, Kapp Levin and Tunheim members.
The Vesalstranda Member consists of alternating finingand coarsening-upward units composed of sandstones, siltstones, mudstones, coaly shales and coals. The fining-upward units represent mainly fluvial channel deposits (Fig. 2-27) with a dominating palaeocurrent direction towards the northwest, whereas the coarsening upward units probably represent lacustrine deltaic sequences (Gjelberg 1978, 1981, 1987).

Fig. 2-27
Fig. 2-27: Fluvial channel in the lower part of the Røedvika Formation, Røedvika, Bjørnøya. Photo: D. Worsley


The Kapp Levin Member consists mainly of fluvial braided and meandering sandstones and conglomerates draining eastwards.
The Tunheim Member consists of fluvial sandstones interbedded with fine-grained flood-plain deposits and coal.
The Røedvika Formation thins westward on Bjørnøya and it is only 120 m thick at SW Alfredfjellet (Horn & Orvin 1928; Gjelberg 1981). The thinning may be caused by angular unconformities within the Carboniferous succession. At Alfredfjellet, the Kapp Hanna and Hambergfjellet formations unconformably overlie the Røedvika Formation.

Fig. 2-28
Fig. 2-28: Stratigraphic section CP-16. Composite stratotype for: Røedvika Formation. Locality: Vesalstranda - Kapp Levin - Tunheim. Reference: Gjelberg 1981 (unpubl.)


Vesalstranda Member (CP-17)
STATUS OF UNIT: Formal
FIRST USE OF NAME: Worsley & Edwards 1976
CURRENT DEFINITION: Worsley & Edwards 1976
SYNONYM(S) AND REFERENCE(S): None. The unit is represented by the "Skrekk" and "Misery subformations" (Russ.: podsvity) of Pavlov et al. (1983).
ORIGIN OF NAME: Vesalstranda: The coastal strip at the foot of Miseryfjellet, E coast of Bjørnøya (type locality)
TYPE SECTION (Fig. 2-29): Stratotype: Vesalstranda, eastern Bjørnøya

Fig. 2-29
Fig. 2-29: Stratigraphic section CP-17. Stratotype for: Vesalstranda Member Locality: Vesalstranda. Reference: Gjelberg 1981 (unpubl.)


DEPOSITIONAL AGE: Famennian
DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Kaiser 1971; Worsley & Edwards 1976
OVERLYING UNIT(S): Kapp Levin Member
UNDERLYING UNIT(S): Pre-Old Red
SUPERIOR UNIT: Røedvika Formation
OTHER USE OF NAME: None
THICKNESS: ca. 200 m, >155 m in stratotype
MAIN LITHOLOGIES: Sandstone, shale, coal
LOWER BOUNDARY DEFINITION: See Røedvika Formation
DESCRIPTION: The Vesalstranda Member consists of coarsening- and fining-upward units of sandstone, siltstone and shale. Coal seams and coaly shale are interbedded with these units. Siderite bands and concretions are often associated with the coals. Plant fossils are common, both within the shales and the sandstones.
The fining-upward units represent flood-plain environments constructed mainly from northwestward flowing streams of high sinuosity and ribbon channel systems. The coarsening-upward units represent a lacustrine deltaic environment constructed mainly from prograding delta lobes into standing water bodies (lakes). The Vesalstranda Member contains approximately 20 coal seams and coaly shales. Most of these are thin, however, but may locally be up to one meter thick (Horn & Orvin 1928).

Kapp Levin Member (CP-18)
STATUS OF UNIT: Formal
FIRST USE OF NAME: Worsley & Edwards 1976
CURRENT DEFINITION: Worsley & Edwards 1976
SYNONYM(S) AND REFERENCE(S): None. The rank 'subformation' (Russ.: podsvita) was used by Pavlov et al. (1983).
ORIGIN OF NAME: Kapp Levin: A cape on the eastern coast of Bjørnøya (type locality)
TYPE SECTION (Fig. 2-30): Stratotype: Kapp Levin, eastern Bjørnøya

Fig. 2-30
Fig. 2-30: Stratigraphic section CP-18. Stratotype for: Kapp Levin Member Locality: Kapp Levin. Reference: Gjelberg 1981


DEPOSITIONAL AGE: Late Famennian - Early Tournaisian
DATING METHOD: Palynology in over- and underlying units
REFERENCE(S) FOR AGE: Vigran 1994 (unpubl.); Worsley & Edwards 1976
OVERLYING UNIT(S): Tunheim Member
UNDERLYING UNIT(S): Vesalstranda Member
SUPERIOR UNIT: Røedvika Formation
OTHER USE OF NAME: None
THICKNESS: 71 m in stratotype
MAIN LITHOLOGIES: Sandstone, shale
LOWER BOUNDARY DEFINITION: The lower boundary is defined at the base of the thick sandstone succession which dominates most of the unit. Conformably underlying lithologies are shales.
DESCRIPTION: The lower part of the Kapp Levin Member consists of relatively thick, fining-upward sandstone units with lateral accretion surfaces. The overlying sandstones and pebbly sandstones reflect a more complex vertical development of alternating sandstones, pebbly sandstones, thin conglomerates and thin shales, probably representing braided stream deposits (Gjelberg 1981). The uppermost part of the member consists of a relatively thick mudstone interval coarsening upwards into conglomerates which constitute the lower part of the Tunheim Member.
The sediments of the Kapp Levin Member are virtually barren of organic material (Vigran 1994, unpubl.), though imprints of lepidodendrid stems are relatively common (Gjelberg 1981).

Tunheim Member (CP-19)
STATUS OF UNIT: Formal
FIRST USE OF NAME: Worsley & Edwards 1976
CURRENT DEFINITION: Worsley & Edwards 1976
SYNONYM(S) AND REFERENCE(S): None. The unit is represented by the "Tunheim" and "Fugle subformations" (Russ.: podsvity) of Pavlov et al. (1983)
ORIGIN OF NAME: Tunheim: An abandoned coal mining settlement, NE Bjørnøya (type locality)
TYPE SECTION (Fig. 2-31): Composite section: Rifleodden (lower part) and Tunheim (upper part), NE Bjørnøya


Fig. 2-31
Fig. 2-31: Stratigraphic section CP-19. Composite stratotype for: Tunheim Member Locality: Tunheim (upper part) / Rifleodden (lower part). Reference: Gjelberg 1981 (unpubl.)


DEPOSITIONAL AGE: Late Famennian - Early Tournaisian
DATING METHOD: Palynology in adjacent units
REFERENCE(S) FOR AGE: see Røedvika Formation
OVERLYING UNIT(S): Nordkapp Formation
UNDERLYING UNIT(S): Kapp Levin Member
SUPERIOR UNIT: Røedvika Formation
OTHER USE OF NAME: "Tunheim series" (Horn & Orvin 1928): lower, coal-bearing part of Tunheim Member; "Tunheim subformation" (Russ.: podsvita; Pavlov et al. 1983): lower part of Tunheim Member. The present definition of the Tunheim Member is wellestablished in the literature and has priority.
THICKNESS: ca. 80 m
MAIN LITHOLOGIES: Sandstone, shale, conglomerate, coal
LOWER BOUNDARY DEFINITION: The lower boundary is defined at the conglomeratic base of the lowermost of the stacked fining-upward sequences that build up the member. The conformably underlying lithology is normaly sandstone.
DESCRIPTION: The Tunheim Member starts with several metres thick conglomerate and pebbly sandstones defined as the "Rifleodden Conglomerate Bed" by Worsley & Edwards (1976), followed by a 20-30 m thick sandstone unit. The member is composed of 3-4 stacked, poorly defined, fining upward sequences, probably representing meandering streams (Gjelberg 1981). The internal organisation of the member is very complex, with several erosional surfaces and mudstone lenses.
The coals of the Tunheim member were mined at the mining settlement of Tunheim from 1916 to 1925.

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NORDKAPP FORMATION (CP-20)

DISTRIBUTION shown on Fig. 2-05
STATUS OF UNIT: Formal
FIRST USE OF NAME: Cutbill & Challinor 1965
CURRENT DEFINITION: Cutbill & Challinor 1965
SYNONYM(S) AND REFERENCE(S): "Ursa Sandstone", upper part: Holtedahl 1920
ORIGIN OF NAME: Nordkapp (transl. "North Cape"): A cape at the N coast of Bjørnøya
TYPE SECTION (Fig. 2-32, Fig. 2-33): Unit stratotype: Landnørdingsvika , SW Bjørnøya Hypostratotype (upper part of formation): Nordhamna, N Bjørnøya.

Fig. 2-32
Fig. 2-32: Stratigraphic section CP-20a/21/22a. Unit stratotype for: Nordkapp Formation, Kapp Harry Member, Nordhamna Member. Locality: Landnørdingsvika. Reference: Gjelberg 1981


The base of the formation is not exposed at the type locality itself, but is found at several localities along the NE coast north of Tunheim (Worsley & Edwards 1976; Gjelberg 1981).
STRUCTURAL SETTING: Early Carboniferous basin of the Western Barents Sea Shelf
DEPOSITIONAL AGE: Tournaisian - Viséan
DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Vigran 1994 (unpubl.); Worsley & Edwards 1976
OVERLYING UNIT(S): Landnørdingsvika Formation, locally Hambergfjellet Formation
UNDERLYING UNIT(S): Røedvika Formation
SUPERIOR UNIT: Billefjorden Group
OTHER USE OF NAME: Nordkapp Basin (southern Barents Sea), from a different locality on mainland Norway
THICKNESS: Up to 230 m
MAIN LITHOLOGIES: Sandstone, conglomerate
LOWER BOUNDARY DEFINITION: The base is defined at the onset of rapidly alternating clastic lithologies including conglomerates above the Røedvika Formation. Horn & Orvin (1928) describe a slight angular unconformity due to regional tilting of the underlying substratum.
DESCRIPTION: The formation is divided into the Kapp Harry Member (below) and the Nordhamna Member (above).
The Kapp Harry Member consists mainly of grey crossstratified sandstones, representing eastward draining braided streams (Gjelberg 1981; Gjelberg & Steel 1981). The Nordhamna Member consists of alternating grey conglomerates, sandstones, pebbly sandstones and grey/reddish shale, representing braided- stream and debris-flow deposits (Gjelberg 1981; Gjelberg & Steel 1981).
The formation thins west- and southwestward and is less than 100 m thick on the southeastern coast (Horn & Orvin 1928). On Alfredfjellet, the Hambergfjellet Formation unconformably overlies tilted and truncated beds of the Nordkapp Formation.

Kapp Harry Member (CP-21)
STATUS OF UNIT: Formal
FIRST USE OF NAME: Here; after Gjelberg 1984 (unpubl.)
CURRENT DEFINITION: Gjelberg 1981
SYNONYM(S) AND REFERENCE(S): None
ORIGIN OF NAME: Kapp Harry: A cape on the SW coast of Bjørnøya (type locality)
TYPE SECTION (Fig. 2-32): Unit stratotype: Kapp Harry at Landnørdingsvika, SW Bjørnøya
DEPOSITIONAL AGE: Tournaisian - ?Viséan
DATING METHOD: Palynology
REFERENCE(S) FOR AGE: Vigran 1994 (unpubl.)
OVERLYING UNIT(S): Nordhamna Member
UNDERLYING UNIT(S): Røedvika Formation
SUPERIOR UNIT: Nordkapp Formation
OTHER USE OF NAME: None
THICKNESS: >50 m in stratotype
MAIN LITHOLOGIES: Sandstone, conglomerate
LOWER BOUNDARY DEFINITION: See Nordkapp Formation
DESCRIPTION: The Kapp Harry Member consists mainly of medium-grained sandstone, dominated by planar and trough cross-stratification, with occasional beds of pebbly sandstone and thin conglomerates. Beds of mudstones (shales) and siltstones are scarce (1.6 %). Beds are usually distinctly lenticular. Soft-sediment deformation structures occur frequently.
The unit represents braided stream deposits. Palaeocurrent indicators suggest an easterly drainage direction.
In addition to the area north of Kapp Harry, the member is well exposed around Nordkapp at the north coast.

Nordhamna Member (CP-22)
STATUS OF UNIT: Formal
FIRST USE OF NAME: Here; after Gjelberg 1984 (unpubl.)
CURRENT DEFINITION: Gjelberg 1981
SYNONYM(S) AND REFERENCE(S): None
ORIGIN OF NAME: Nordhamna (transl. "North Harbour": A bay on the northern coast of Bjørnøya (locality of reference stratotype)
TYPE SECTION (Fig. 2-32, Fig. 2-33): Unit stratotype: Landnørdingsvika , SW Bjørnøya Hypostratotype: Nordhamna, N Bjørnøya

Fig. 2-33
Fig. 2-33: Stratigraphic section CP-20b/22b. Hypostratotype for: Nordkapp Formation, Nordhamna Member. Locality: Nordhamna. Reference: Gjelberg 1981


DEPOSITIONAL AGE: Viséan
DATING METHOD: Palynology in adjacent units
REFERENCE(S) FOR AGE: See Nordkapp Formation
OVERLYING UNIT(S): Landnørdingsvika Formation
UNDERLYING UNIT(S): Kapp Harry Member
SUPERIOR UNIT: Nordkapp Formation
OTHER USE OF NAME: None
THICKNESS: >65 m in stratotype
MAIN LITHOLOGIES: Sandstone, conglomerate, shale
LOWER BOUNDARY DEFINITION: The lower boundary of the member at the type locality is defined at the base of a prominent interval of alternating siltstone and shale (> 10 m thick), with conformably underlying sandstones of the Kapp Harry Member.
DESCRIPTION: The Nordhamna Member consists of alternating cross stratified grey sandstones, pebbly sandstones, grey conglomerates (composed of quartzitic and chert pebbles) and grey or greyish-red siltstone and shale with thin coaly shale interbeds (Gjelberg 1981; Gjelberg & Steel 1981).
The sharp environmental change from the Kapp Harry Member to the Nordhamna Member may reflect the early onset of a climatic and/or tectonic change whose main effect was felt in Bashkirian times (Gjelberg & Steel 1981, 1983; Steel & Worsley 1984; Gjelberg 1987). The sediments of the Nordhamna Member represent mainly braided stream deposits, probably closely associated with an alluvial fan system. The thick units of fine-grained sediments may represent flood-plain or lacustrine deposits.
In addition to the type locality, the Nordhamna Member is also well exposed in Nordhamna and Kobbebukta on the northern coast. The member is not completely exposed at these localities, and it is difficult to make a reliable thickness estimate there. However, data from borehole 1 (at Laksevatnet) and borehole 7 (S end of Hausvatnet) tentatively suggest that the member thickens slightly towards the east (Horn & Orvin 1928, Gjelberg 1981).

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