Climate change and response in bottom water circulation and sediment provenance in the Central Arctic Ocean since the Last Glacial

• Main Authors: Meinhardt, A., Pahnke, K., Böning, P., Schnetger, B., Brumsack, H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Amundsen Basin; Arctic; Arctic Ocean; Canada; Makarov Basin; amundsen basin; canada basin; Central Arctic; Climate change; Lomonosov Ridge; makarov basin; North Atlantic Deep Water; North Atlantic
• Online Access: http://hdl.handle.net/21.11116/0000-0001-C351-7; http://hdl.handle.net/21.11116/0000-0006-8000-8

In this study, Arctic Ocean patterns of deep water circulation and sediment provenance during the Last Glacial (LG) were compared with the recent situation by investigating the Nd and Sr isotopic composition (143Nd/144Nd, expressed as εNd, 87Sr/86Sr) of the leachable and lithogenic sediment fractions as well as the elemental composition (Mn, Ca, Mg, total inorganic carbon (TIC)) on a spatially extended scale encompassing 11 sediment cores from several Arctic Ocean basins and ridges. The leachable, authigenic signature of the surface sediments implies a North Atlantic deep water source and a late Holocene circulation regime that leads to well-mixed, mostly uniform, εNd values of − 10.9 to − 10.3. Sediments from the LG have overall more variable authigenic εNd values (− 13.9 to − 7.4). Lower values specifically occur in the Amerasian and Amundsen Basins, documenting an enhanced flow of deep waters from the Makarov Basin to the Amundsen Basin probably via the Lomonosov Ridge intra-basin. In terms of detrital provenance areas, the lithogenic material deposited at the core locations cannot be unambiguously assigned to distinct source areas based on its radiogenic isotope composition, but represents a diverse mixture. Nevertheless, the Nd and Sr isotope signatures of surface sediments from the Amerasian Basin are dominated by western Arctic sources (εNd = − 12.8 to − 11.0; 87Sr/86Sr = 0.7214 to 0.7251), while Eurasian Basin surface sediments are dominated by Eurasian sources (εNd = − 10.9 to − 9.7, 87Sr/86Sr = 0.7178 to 0.7299), which is in agreement with previous studies. Bulk element patterns (Ca, Mg, TIC) of the studied sediments support these differences in provenance. The LG samples show the same trends with low εNd (− 16.1 to − 13.7) and high 87Sr/86Sr (0.7294) in the Canada Basin, and higher εNd (− 12.6 to − 8.8) and lower 87Sr/86Sr (0.7154 to 0.7249) in the Eurasian Basin sediments. However, LG samples have mostly lower and more heterogenous εNd and 87Sr/86Sr values than the surface samples. Our geochemical ...