NJG71-4-03
1991
The transition from deposition of condensed carbonates to dark claystones in the Lower Cretaceous succession of the southwestern Barents Sea
71
4
pp. 259-263

Four shallow coreholes in the area 72°45'-74°30 'N and 21°-31°E penetrate 3 to about 15m thick Boreal Berriasian to Lower Barremian marls, claystones of different colours and carbonates. The Berriasian seems to be missing in the two southernmost hoies. Lithostratigraphical units are in general problematic to correlate although light grey fossiliferous packstone of Valanginian age are widely distributed (also known from Kong Karls Land). An abrupt facies change from condensed carbonates to dark clay deposition took place at slightly different times within the Early Barremian. In 7425/9-U-1 and 7430/10-U-1 the upper part of the carbonates is very dark and rich in Inoceramus debris. The upper part of these can be assigned to the middle part of the Barremian, H. rude-fissicostatum ammonite Zone, whereas in 7320/3-U-1 the top of the limestones may be Hauterivian in age. In 7231/1-U-1 in the Nordkapp Basin the age at the top of the limestone is close to the Hauterivian/Barremian boundary. The Lower Barremian including the H. rude-fissicostatum Zone may be represented by a 0. 3 m thick calcareous transitional bed with clay clasts in its upper part. Normal clay sedimentation was initiated in post H. rude-fissicostatum Zone equivalent time, in contrast to in the three other cores and in a section on Kongsøya, Kong Karls Land.

Nils Århus, N-2866 Enger, Norway

0029-196X
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