Abstract
AbstractThe topography in Scandinavia features enigmatic high-elevation low-relief plateau regions dissected by deep valleys and fjords. These plateau regions have long been interpreted as relict landforms of a preglacial origin, whereas recent studies suggest they have been modified significantly by glacial and periglacial denudation. We used late Pliocene–Quaternary source-to-sink analyses to untangle this scientific conundrum. We compared glacier-derived offshore sediment volumes with estimates of erosion in onshore valleys and fjords and on the inner shelf. Our results suggest that onshore valley and fjord erosion falls 61%–66% short of the offshore sink volume. Erosion on the inner shelf cannot accommodate this mismatch, implying that the entire Scandinavian landscape and adjacent shelf have experienced significant glacial erosion.
Highlights
The characteristic high-elevation low-relief plateau regions in Scandinavia have traditionally been interpreted as remnants of a preglacial surface, with glacial erosion limited to overdeepening of existing valleys (e.g., LidmarBergström et al, 2000; Japsen et al, 2018)
Others have since argued that this excess material can be accounted for by erosion of Mesozoic and Cenozoic sediments on the inner shelf (Hall et al, 2013) that are cropped by the glacial sediments in a prominent angular unconformity of Middle Pleistocene age (e.g., Sejrup et al, 1995)
Our compilation of offshore sediment volumes results in an estimated total volume of ∼364 × 103 km3 sourced from the Scandinavian region and the adjacent shelf (Fig. 3)
Summary
The characteristic high-elevation low-relief plateau regions in Scandinavia have traditionally been interpreted as remnants of a preglacial surface, with glacial erosion limited to overdeepening of existing valleys (e.g., LidmarBergström et al, 2000; Japsen et al, 2018). Earlier work has shown that fjord incision alone cannot account for the erosional volumes deposited offshore during glacial times, indicating several hundred meters of erosion on the plateau surfaces (Steer et al, 2012). We quantify inner-shelf erosion with an approach that is consistent with onshore-offshore profiles from the region and extends inner-shelf erosion estimates to the whole margin. This allows us to include inner-shelf erosion in quantitative source-to-sink analyses. Quantifying the contribution from inner-shelf erosion to the late Pliocene–Quaternary sediment budget allows us to infer onshore erosion beyond the glacial troughs
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