Nature and Timing of Tectonic Contraction and Inversion in the Western Barents Sea

Roy H. Gabrielsen¹, Jan Inge Faleide¹, Ivar Grunnaleite², and Karen A. Leever^1
1Department of Geosciences, University of Oslo, Oslo, Norway.
²International Research Institute of Stavanger (IRIS), Stavanger, Norway.

The western Barents Sea, which has been dominated by extension and basin formation since Late Paleozoic times, is still characterized by numerous structures indicating that the general subsidence has been interrupted by events of tectonic inversion and even large-scale contraction. Generally, however, such structures are either concentrated along the continental margin or in belts associated with major, deep-seated fault systems. In this picture, the West Spitsbergen Fold-and-Thrust Belt stands out in that it incorporates a thick-skinned and a thin-skinned part, that its shortening measured on the scale of tens of km and that it has a complex kinematic development as seen along its strike. Also the Sørvestsnaget Basin area, including the western flanks of a system of highs that separate this basin from the deep Cretaceous basin system in the east (Bjørnøya and Tromsø basins), has a particularly complex history, including local, intense folding and steep faults indicative of larger-scale strike-slip (transpressional) movement.

In contrast, the inverted fault complexes that delineate the major basins in the more stable parts of the shelf area to the east, are characterized by reactivation of pre-existing large faults. In more detail, however, even these display contrasting histories and modification during head-on inversion as well as strike-slip (transpressional and transtensional). For example, four separate stages of extension and inversion/uplift can be identified in the NE-SW-trending Bjørnøyrenna Fault Complex: (1) Late Jurassic-Early Cretaceous extension and subsidence, (2) Late Cretaceous dextral transtension, (3) Cenozoic head-on contraction followed by (4) regional uplift and erosion.

Comparing the fault pattern and relative dating by seismic correlation it is suggested that inversion events are not synchronous in the master fault systems throughout the western Barents Sea. We therefore suggest the following subdivision of the areas that has undergone contraction and inversion: (1) West Spitsbergen Fold-and-Thrust Belt (Late Paleocene-Eocene), (2) East Svalbard (Late Paleocene-Eocene), (3) Central Barents Sea continental margin (Miocene), and (4) SW Barents Sea and its western margin (?Late Cretaceous -Cenozoic).

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