Salt Distribution and Sub-Salt Basins on the Conjugate Barents Sea - Northeast Greenland Continental Shelves

Sverre Planke

Late Devonian to Permian sedimentary sequences are well-exposed and studied on Svalbard, Bjørnøya, and onshore northeast Greenland. However, much less is known about these sequences in the offshore continental shelves. Major Paleozoic rift basins formed in the northeast Atlantic after the collapse of the Caledonian mountain chain. Late Devonian and Carboniferous clastic sequences, coal beds, and organic-rich shales were deposited in these basins. The rifting period was followed by a tectonically more quite period with deposition of limestones and evaporites during the Late Carboniferous and most of the Permian. We have mapped the regional distribution of salt structures in the southwest Barents Sea and on the northeast Greenland shelf using the integrated seismic-gravity-magnetic (SGM) method. The mapping was done using an extensive seismic data base and both shiptrack and aerial potential field data acquired during the past eight years. Salt diapirs are abundant in several basins, such as the Nordkapp, Tromsø, and northern Danmarkshavn basins. However, salt diapirs are also identified in the Bjørnøya and Sørvestsnaget basins and in the southern Danmarkshavn Basin. The salt diapirs are sometimes detached from the source layer, e.g., in the Sørvestsnaget Basin. More gentle salt domes and unmobilized salt are also present regionally, e.g., in the Ottar and Maud basins. The salt diapirs sometimes extend all the way to the seabed. We have sampled one diapir and the surrounding Upper Cretaceous sedimentary sequences subcropping at the seabed on the northeast Greenland shelf. The seabed gravity core samples allow a geological tie of the seismic sequences and provide a maximum age of final salt mobilization. We speculate that minor salt mobilization in the southwest Barents Sea may have caused faulting of the overlying Triassic sequences, and that these faults may thus not reflect any regional tectonic events. Finally, salt deposits are very good hydrocarbon seals. Sub-salt prospect may locally exist in basin provinces with flat-lying salt. However, these prospects are currently hard to interpret due to difficult seismic imaging of the Paleozoic sequences.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013