Rift Basin Evolution of the SW Barents Sea

Stephen A. Clark¹, Jan Inge Faleide¹, Oliver Ritzmann², Evy Glorstad-Clark¹, Rolf Mjelde³, and Willy Fjeldskaar^4
1Dept. of Geosciences, Univ. of Oslo, Oslo, Norway.
²E.ON-Ruhrgas, Essen, Germany.
³Dept. of Earth Science, Univ. of Bergen, Bergen, Norway.
⁴International Research Institute of Stavanger, Stavanger, Norway.

We present a tectonic model of progressive basin formation in the SW Barents Sea as part of the PETROBAR project (Petroleum-related studies of the Barents Sea region). The basin architecture of the SW Barents Sea developed as a multi-stage rift preceding the creation of the sheared/transtensional margin conjugate to NE Greenland. N- to NNE-striking basins, with depths in places exceeding 15 km, are separated by basement highs. Our model utilizes BMT™ software to resolve the subsidence, stretching factor, and temperature distribution through discrete time intervals along the long-offset seismic reflection/refraction profile PETROBAR-07. This ~700 km-long profile is coincident with the deep multichannel seismic reflection profile IKU-B acquired in 1984. Detailed stratigraphic analysis of the reflection profile provides timing and paleo-water depth constraint for the model, while velocity analysis of the long-offset profile provides constraint on the crustal structure and thickness.

The NW-trending cross-section extends continuously from continental craton, at the Varanger Peninsula, to oceanic crust, at the interpreted COB. Rifting along the profile was episodic, with three distinct phases of basin formation. Nordkapp and Ottar basins formed during the initial phase of rifting, in the Carboniferous. Loppa High separates these basins from a second, Late Jurassic-Early Cretaceous rift phase which formed Bjørnøya Basin. The final phase of rifting occurred during the Late Cretaceous-Eocene, forming basins beneath the Vestbakken Volcanic Province. Collectively, the basins exhibit a general trend of younging, narrowing, and deepening oceanward, suggesting a gradual focusing of rifting prior to final breakup. Our modeling results have important implications for understanding petroleum systems and constraining paleogeography. Initial estimates of cumulative stretching are in accord with recently published plate tectonic reconstructions. Details of the subsidence and thermal history during rift evolution provide critical information for understanding hydrocarbon maturation in the region.

AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia