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The topographic relief of the Barents Sea was subjected to major changes during the past 1.5 million years mostly due to sediment redistribution driven by glacial activity. This paper addresses the problem of Pleistocene bathymetric evolution of the southern Barents Sea using a numerical modelling approach that considers the influence of regional isostasy on relief development. The model presented in this work shows that most of the bathymetric features were initiated prior to the first documented, shelf-edge glaciations at around 1.5 Ma. During the Early Pleistocene (Calabrian), the Barents Sea shelf was close to sea level with some areas elevated to about 300 m. Most of the shelf experienced up to 200 m topography reduction during the Early to Middle Pleistocene (1.5-0.7 Ma) facilitating bifurcation of the North Atlantic waters into the Barents Sea. Later during the Middle Pleistocene-Present (0.7-0.0 Ma) the relief deepened by 0 to 250 m. Our results demonstrate that the present-day topography of the southern Barents Sea is the consequence of glacial activity influenced by a regional isostatic component, which is the result of selective trough erosion and significant sediment deposition at the Barents Sea margins during the Pleistocene.

The Cenozoic uplift and erosion is often believed to be a major risk factor in hydrocarbon exploration in the Barents Sea causing petroleum redistribution and leakage from filled traps. Therefore, the estimation of erosion amount is an important but often underrepresented task in the basin modeling procedure. The assessment of erosion magnitudes and spatial distribution by geochemical and thermo chronological methods results in very different estimates and/or does not consider uncertainties of input data. In this study, this problem is approached by using Monte Carlo simulation techniques in secondary migration basin modeling. Thereby, amounts of early and late Cenozoic erosion episodes are described by probability distributions and the modeling results were evaluated considering their uncertainty ranges. In addition, overpressure and related leakage scenarios are considered in the petroleum basin models to study their effect on modeling results. It is shown that the early Cenozoic erosion event had a generally higher erosion magnitude than the late Cenozoic event (1.0-1.3 and 0.4-1.2 km respectively). Modeled erosion estimates are not very sensitive to overpressure modeling which is found to affect only the early Cenozoic erosion amount estimates at low degree.

The Pleistocene sedimentary conditions and the glacial contribution to net erosion were determined for the outer Bear Island Trough by using a Monte Carlo-type method. The approach uses ages for glacial/interglacial periods that were based on the regional ice-sheet volume curve. The results indicate that the western Barents Sea was glaciated during four marine isotope stages: MIS 16 (635.6-624.7 ka), MIS 12 (438.7-428.0 ka), MIS 6 (138.6-134.6 ka) and MIS 2 (19.3-16.0 ka) for a total duration of 29 ka. The first glacial event (before 440 ka, MIS 16) resulted in homogeneous erosion over the study area (with an erosion rate of 24.2 ± 8.5 mm/a). After 440 ka, a change in sedimentary conditions resulted in inhomogeneous erosion rates over the study area from -12.6 ± 1.6 (i.e. net deposition) to 1.6 ± 1.8 mm/a (i.e. net erosion). The most likely values of average deposition rates during interglacial periods were modelled as 0.12 ± 0.1 mm/a. In the outer Bear Island Trough the net erosion was found to be mainly the effect of tectonic uplift and subsequent erosion prior to the glacial ages. The results show that in most parts of the study area the Pleistocene glacial contribution to the total net erosion was small: the most likely glacial contribution in the eastern part of the area reaches 100 m, which is about 9 % of the total net erosion, while in the westernmost part the glaciations did not contribute to the net erosion.