Recurrent Mass-wasting in Sørvestsnaget Basin, SW Barents Sea: A test of multiple hypotheses

Abstract:

Mass-wasting on the NE Atlantic margin is commonly attributed to Cenozoic glaciations. Using high-quality and high-resolution seismic dataset, this study investigates the types and mechanisms driving mass-wasting in the Sørvestsnaget Basin, Southwestern Barents. Seven mass-transport deposits (MTDs) ranging in age from Late Miocene to Holocene are interpreted on seismic profiles. The MTDs are vertically stacked from about 1900 ms TWTT to the present seabed. MTD 5 (area ca.1.22 x 10³ km², volume ca.3.4 x 10³ km³) is the largest deposit in the study area and is composed largely of debrites and rafted blocks underlain by thin layers of hemipelagic sediments. Miocene and Early Pliocene MTDs in the basin demonstrate tendency for initial translation through canyons and channels. The youngest MTDs in the area are composed of glacigenic sediments remobilized by ice streams during Late Neogene and Quaternary glaciations. In the southern part of the study area, deep-water sediments fed through V-shaped canyons and channels are widespread signifying the Stappen High as the main sediment source area prior to the Late Pliocene. The prevalence of shallow marine successions in the northern part of the study area is linked to the southwesterly propagation of the shelf break from Miocene to Recent times. In this study, the shelf break trajectory is important for reconstructing paleo-sediment routes and dispersal pattern. The older non-glacial MTDs are separated farther from their paleo-shelf break. Mass-wasting is a recurrent process in the Sørvestsnaget Basin. Triggering mechanisms for slope failure in the basin may include increased pore pressure as a result of sea level fall and high sedimentation rate, over-steepened slope, glaciation, volcanism, and gas hydrate dissociation. Mass-wasting in the study area occurred through progressive, retrogressive and whole body or coherent downslope failures.