SHALLOW BEDROCK GEOLOGY OF THE OLGA BASIN AREA, NORTHWESTERN BARENTS SEA

The east-west-trending Olga Basin has possibly the largest post-Jurassic sedimentary rock thickness in the northwestern Barents Sea. The thickness of these mainly shallow-marine deposits exceeds 750 m in the study area, and increases eastward. The Olga Basin is characterized by relatively undisturbed layers, which except for local areas, rarely dip more than 3-degrees. The Storbanken area is heavily penetrated by normal faults, which probably are related to the Late Cretaceous uplift in the region. Differential uplift along the flanks of the Olga Basin during the Oxfordian-Hauterivian led to deposition of onlapping units in the central parts, whereas erosion and limited deposition prevailed on the topographic highs. The overlying Barremian sequence is more uniform and is at least 350 m thick. In the Hammerfest Basin in the southern Barents Sea, corresponding Barremian deposits are found. The post-Jurassic strata contain sandstones of three different kinds: subarkose-sublitharenite, litharenite, and lithic arkose. The Barremian subarkoses-sublitharenites have relatively high porosities and may be potential reservoir rocks. The organic geochemistry analyses show somewhat higher hydrogen index values than those foundin the corresponding sedimentary strata on Spitsbergen; however, the strata are slightly less mature than the corresponding strata on Spitsbergen.