Knowledge of the general geology of the Barents Sea has been gained by seismic and other geophysical surveys within the sea itself and by projecting the geology from the land areas bordering the sea. A mosaic of structural highs and lows is recognized. An abrupt velocity change of 1 to 2.5 kmps within the Permian sediments divides the sedimentary section into upper clastic and lower, largely carbonate complexes.
UPPER CLASTIC COMPLEX: This section consists of sediments from Kungurian or Ufimian age of the Permian to the Quaternary. It contains six reflecting horizons.
Quaternary sediments. The base of the Quaternary coincides with reflecting horizon E. Thickness of these sediments ranges from 20 to 100 m, and they consist of a variety of clastics from cobbles to clays. The top of this unit is reflecting horizon F and is commonly recorded somewhat lower than the actual surface of the sea floor at the boundary between liquid and semi-liquid bottom mud and the more consolidated older sediments. Average velocity in these sediments is 1.70-1.74 kmps.
Paleogene and Neogene (?) sediments. Beneath the Qua- ternary at a number of places are sediments with a somewhat greater velocity signature at 1.79-1.82 kmps. They are up to 1 km thick. The age designation is conditional, based on comparison with known Tertiary sediments. It is assumed that sandy-clayey varieties predominate. Some volcanics may be present at the base of the section.
Cretaceous sediments. Beneath the discontinuous and generally thin Cenozoic sediments is a Cretaceous section, which is fairly widely distributed. It is bounded above by reflecting horizon E and below by reflecting horizon D. The velocity is uniform at 1.96-2.05 kmps. Thickness of the Creta- ceous ranges from 0.2-0.5 km in the southeast to 1.0-1.5 km in the South Barents depression, to 1 km in the Novaya Zemlya downwarp, to 0.2-0.6 km in the Olga and Medzhev depressions. It consists of sand-silt-clay varieties, passing into volcanics on Franz Josef Land.
Jurassic sediments. Within the Jurassic section is the very reliable seismic horizon C, which has been traced over large areas. Its depth range is from a few hundred meters on the highs to 2-2.5 km in the depressions. A maximum depth of 3 km has been found in the South Barents depression. This reflector is correlated with the top of a dense sandstone in the Middle Jurassic, where velocity difference is 0.5-0.7 kmps. The upper part of the Jurassic between reflecting horizons C and D consists of marine clays, some of which are bituminous. Interbeds are siltstone, rarely sandstone. The lower part below horizon C consists of sands and smaller amounts of siltstone and clays. Detrital plant matter is abundant. This part of the section is the Sysol Formation. Thickness of the Jurassic between horizons C and D is 250-1000 m in general and conformable with the underlying Triassic except on Novaya Zemlya where an angular unconformity is present.
Taken from Verba, 1984, one tectonic map and three cross
sections; digested in Petroleum Geology, Vol. 23, No. 5/6.
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