Impact of the Pleistocene Glaciations on Net Erosion Development in the Western Barents Sea

Abstract:

The Barents Sea shelf was subjected to both tectonic- and glacially-driven erosion during the Cenozoic. It is however unclear which of the erosion mechanisms had the most important role in generating net erosion that indicates a total effect of all erosion events. The literature estimates of glacial to tectonic erosion ratio vary significantly and often do not account for regional variations. The tectonic erosion is often attributed to plate reorganization in the Norwegian-Greenland Sea during the Cenozoic. The literature shows wide diversity of opinions regarding timing and thickness of the tectonic erosion. In contrast, glacial erosion thickness estimates are well constrained and show lower discrepancy in results. The glacial erosion thickness estimates are therefore key information that can be used for constraining the ratio between tectonic and glacial erosion. The glacial contribution to the net erosion is however also controlled by on-shelf deposition that counteracts the process of glacial erosion. However the on-shelf deposition rates have never been calculated. In result, the Pleistocene sediment budget and glacial contribution to the net erosion has never been assessed yet.

The Pleistocene contribution to the net erosion was approached by a new Monte-Carlo-type method where the Pleistocene-Holocene sediment budget is calculated and the net erosion thickness is determined as a balance between total deposition and erosion thicknesses. The proposed method requires definite ages of glacial and interglacial periods what is not available in the literature. The timeframe was established by using a new approach based on the regional ice-sheet volume curve. Also, the new glacial/interglacial timeframe enables calculating the erosion rates for glacial duration (10³ – 10⁴ yr) timescale what have not been performed before.

The results show that the western Barents Sea was glaciated during 4 marine isotope stages for a total duration of 29 kyr. The glacial erosion rates range between 25 and 40 mm/yr. On-shelf deposition rates vary from 0 to 35 mm/yr. In the western Barents Sea 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 the Pleistocene glaciations did not or slightly contributed to development of the net erosion.