Formation of Pull-apart Basins and Sediment inFill from Uplifted Areas in the SW Barents Sea

Brit Thyberg

The SW Barents Sea margin developed from a meagashear zone which linked the Norwegian-Greenland Sea and the Artic Eurasia Basin during the initial Eocene opening. Within the dextral megashear system, a series of pull-apart basins formed in the SW Barents Sea (and in the Wandel in NE Greenland). These basins formed in response to multiple rift events, mainly between onset of late Middle Jurassic rifting and final crustal break up at the Paleocene-Eocene transition. Late Middle Jurassic to Early Cretaceous rifting affected all deep basins in the SW Barents Sea (e.g., Bjørnøya, Tromsø, Harstad and Sørvestsnaget basins) while the Late Cretaceous-Paleocene rifting was mainly focused in the Sørvestsnaget Basin. The northern Sørvestsnaget Basin and Vestbakken Volcanic Province formed in a pull-apart setting related to a releasing bend in the margin. These sedimentary basins subsided rapidly and received large amount of erosional products from the uplifted Barents Shelf, in particular the Stappen High in the north (surrounding Bjørnøya). New 3D seismic surveys (acquired by Fugro Multiclient Services) cover both the source and sink in this complex area which comprises untested potential Mesozoic and Cenozoic plays. Interpretation of the 3D data, integrated with regional 2D long-offset lines, enhance the understanding of the prospectivity and regional geological development in the area. Seismic data show clinoforms which can be interpreted as Eocene progradation into northern Sørvestsnaget Basin from the uplifted Stappen High. Furthermore, interval velocities derived from the 3D velocity cubes were used to guide the seismic interpretation. The different structural domains, bounded by major faults, reveal rather different velocities, which have to be interpreted in the context of differential vertical movements across the major faults, as well as the prominent Late Neogene uplift and erosion which affected the entire Barents Shelf.

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