Buried Glacial Geomorphic Features Identified Using 3D-Seismic Data in the Southwestern Barents Sea, Arctic Norway



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The Barents Sea covers one of the world's widest continental shelves, averaging 230 m in water depth. Over the last 3.5 My, the growth and retreat of ice sheets grounded on the shallow shelf and eroded up to 3000 m of sediment in the sea. Glacial erosion was particularly concentrated ~1.0 Ma, when multiple ice sheets converged and completely covered the Barents Sea for the first time. During this period of convergence, flowing ice beneath the ice sheet eroded the substrate and floating icebergs carved features into the sedimentary cover. As the ice sheet retreated, new sediment was deposited over the formerly ice-covered surface, preserving glacial features in the subsurface. Identification and analysis of the features beneath the modern-day seafloor can illustrate past ice-sheet characteristics arising before the last glacial maximum, such as paleo-ice flow direction or changes in flow patterns. This study interprets 3D-seismic grids covering ~2000 km2 to identify glacial features on the Upper Regional Unconformity, a regional unconformity representing the onset of glaciation. This method of examining glacial history is exclusively possible in areas such as the Barents Sea, which has available 3D-seismic data of glaciated margins for the petroleum industry. A series of parallel, evenly-spaced lineations ranging from 0.5-9 km in minimum length, trending northwest-southeast, has been identified in the subsurface. In comparison to previous seafloor studies, which mark the direction of ice flow from the last glacial maximum (~20 ka), these northwest-southeast oriented lineations, trending ~340°-345°, indicate northwest paleo-ice flow and are interpreted to form parallel to ice flowing towards Bjørnøyrenna Trough, an area of extensive former ice stream activity. The seafloor surface shows evidence of iceberg scours carved by drifting icebergs following ice-sheet retreat after the last glacial maximum. The subsurface also has evidence of iceberg scours, as well as other features including glacial lineations, erosional grooves, and meltwater depressions. Analysis of glacial geomorphology from seismic data can be used to examine paleo-ice flow and subglacial erosion. By comparison to features found in other glaciated environments, it can lead to a better understanding of current and future ice-sheet behavior.



Glacial geomorphology, Barents sea, 3D seismic data