Recurrent mass-wasting in the Sørvestsnaget Basin Southwestern Barents Sea: A test of multiple hypotheses

Abstract

Mass-wasting on the NE Atlantic Margin is generally attributed to Cenozoic glaciations. Using high-quality 2D seismic datasets and two exploration wells, this study investigates the types and driving mechanisms of mass-wasting in the Sørvestsnaget Basin, Southwestern Barents Sea. The methods include seismic interpretation of shelf margin clinoforms, mass-transport deposits (MTDs), submarine channels and V-shaped canyons. The shelf-edge trajectory provided information about sea-level conditions, paleo-sediment routes, and dispersal patterns during the evolution of the basin. In terms of the internal geometry of seismic reflectors, the major depositional units are five sedimentary packages (P1 to P5) characterized by distinct southwest dipping shelf margin clinoforms. Seven identified MTDs have Late Miocene to Pleistocene ages. Miocene and Early Pliocene MTDs in the basin demonstrate a tendency for initial translation through canyons and channels. The youngest MTDs are composed of glaciogenic sediments remobilized by ice streams during large-scale Neogene and Quaternary glaciations. This work shows that mass-wasting has been a recurrent and inherent process in the Sørvestsnaget Basin from the Miocene until recent times. The main triggering mechanisms for slope failure in the basin are interpreted to be increased pore pressure from sea-level fall and high sedimentation rate. Mass-wasting in the study area occurred through progressive, retrogressive and coherent downslope failures.