Stratigraphy in Billefjorden trough
- Gipshuken Formation: From
150- 250 m thick, these Artinskian carbonates and evaporites
are widespread, stable shelf deposits (McCann & Dallmann, 1996).
- Nordenskioldbreen Formation:
This is more recently known as the Wordiekammen Formation and consists
of 200-250 m of platform carbonates of Kasimovian to Sakmarian
age. A lack of thickness or facies changes across the Billefjorden
fault zone in this unit suggests movement was over by then. In the field
they appear as medium grey, well bedded carbonates.
- Minkinfjellet Formation:
0 - 350 m. Its distribution and absence on the Nordfjorden
footwall block suggest this is part of the basin fill. Given the thickness
of the underlying fill, compaction processes are inadequate to provide
this accommodation space and so continued half-graben development can be
inferred. They are interpreted to be open marine deposits of Moscovian
age (Johannessen & Steel, 1992). Their restriction to the basin,
however, suggests that water depths were not great enough to allow for
- Ebbadalen Formation: Bashkirian age.
- Odellfjellet Member: Up
to 400 m thick of red, grey, and yellow conglomerates and sandstones, red
shales and yellow dolomites. Johannessen & Steel (1995) indicate these
are clastic wedges built out from the Billefjorden fault zone.
- Trikolorfjellet Member:
Gypsum/anhydrite (sabkha deposits intercalated with black/yellow limestones/dolomites.
Some red sandstone and mudstone related to facies transition with Odellfjellet
Member. According to Johannessen & Steel (1992) represents axial basin
- Ebbaelva Member: This
is up to 200 m thick, and stretches across the basin. Grey-green shales
intercalated with grey/yellow sandstones. Transitional with overlying formation
with thin carbonates and evaporites. Braided stream, playa lake, barrier
shoreline, sabkha and lagoonal facies all represented according to Johannessen
& Steel (1992), and part of a transgressive tract. Douglas and Lamar
(1995) suggest an slight angular unconformity exists at the base.
- Hultberget Member: belongs
in the Gipsdalen Group according to Johannessen & Steel (1992), and
defined to only include about 150 m of continental red sandstones and interclated
red siltstones. Thought to be ephemeral streams on alluvial fans.
Billefjorden Group: 0-450 m, Visean
- Svenbreen Formation
- Hultberget Member: This
belongs to Billefjorden Group according to McCann & Dallmann (1996).
See above for description.
- Sporehøgda Member:
Little description exists of this unit. McCann & Dallmann (1996)
note that is its often mapped as part of the lower Horbyebreen Formation.
Lamar & Douglas (1995) describe them as fining upwards cycles of coarse
pebble conglomerates to mudstones, with olive-gray to red-gray and red-brown
coloration. Wackes are common, with possible Hecla Hoek lithics. Sedimentologically,
this would possible represent inception of movement on the Billefjorden
fault zone. They interpet these as high-sinuousity fluvial deposits.
- Hørbyebreen Formation:
Upo to 450 m thick, these are described as fluvial Gjelberg &
Steel (1981) indicate west flowing braided streams, and nearshore marine
sandstones with minor shales, conglomerates and coal seams (McCann &
Dallmann, 1995). Gjelberg & Steel (1981) indicate west flowing braided
streams. Clasts are predominantly quartzite. Lithologically this is similar
to the Orustdalen Formation of western Spitsbergen. Importantly these are
found on both the foot and hangingwall of the Billefjorden fault zone.
Andree Land Group: Wood Bay Fm. A mixed and
multi-colored sequence of clastics from shales to conglomerates. Cleavage
and fairly complex deformation just W of the BFZ makes recognition of stratigraphic
units more difficult. Lamar & Douglas (1995) describe lithologies and
formational stratigraphy in much more detail. The interpretation is of coastal
plain fluvial environments close to sea level with occasional flooding introducing
estaurine and marine influences.
Basement: various schists,
gneisses, amphibolites and minor quartzite and marble interbeds as part
of the Atomfjella Group (McCann & Dallmann, 1996).