Evidence of faulting contradicts a quiescent northern Barents Shelf during the Triassic

Abstract

It has generally been considered that the Triassic was a tectonically quiescent period on the northern Barents Shelf. Located on the distal Uralide foreland, sedimentation was dominated by the advance of prograding deltaic systems. The Triassic succession exposed on Edgeøya (east Svalbard) displays two interacting types of growth fault: listric faults that sole out in the Triassic pro-delta/marine shales; and steeper, more planar, normal faults with a deeper-seated origin. In the nearby offshore realm, 2D seismic data suggest a previously undocumented phase of minor extensional movements during the Triassic that renewed activity on deep-rooted faults initiated during the Palaeozoic. The faults strike approximately east–west, onshore and offshore, with most fault throws down to the south. The seismic data in the Upper Triassic sequence also show smallscale offsets, curved reflectors, and a generally more chaotic signature suggestive of syn-sedimentary disruption. The coeval timing and orientation suggest a link between the reactivation of faults that reach the basement and the development of shallow growth faults. Triassic fault activity has previously been documented in the south. Its occurrence in the north, too, suggests a regional, crustal-scale driving force. We speculate that Uralide foreland deformation preferentially reactivated older east–west basement-seated fault zones.