Clay mineral and Nd, Pb, and Sr isotope provenance of a MIS 4-3 sediment record from the Lomonosov Ridge, central Arctic Ocean

• Published in: Bulletin of the Geological Society of Finland
• Main Authors: Raisa Alatarvas, Ninna Immonen, Kari Strand
• Format: Article in Journal/Newspaper
• Language: English
• Published: Geological Society of Finland 2023
• Subjects: lomonosov ridge; arctic ocean; marine sediments; middle weichselian glaciation; clay mineralogy; nd-sr-pb isotopes; Geology; QE1-996.5; Arctic; Arctic Ocean; Dammed Lake; Kara Sea; Laptev Sea; Iceberg*; laptev; Lomonosov Ridge; Siberia
• Online Access: https://doi.org/10.17741/bgsf/95.1.003; https://doaj.org/article/7d33ffeac795429d808e0bd80be1cc9a

Modern techniques for detrital mineral provenance were applied to sediment core 96/12-1pc from the Lomonosov Ridge in the central Arctic Ocean. The techniques include quantitative clay mineralogy analysis combined with determination of Nd, Pb, and Sr isotopes from clay fraction. The clay mineral assemblage and the isotope signatures depict distinct changes during the Marine Isotope Stage (MIS) 4-3 transition corresponding to the Middle Weichselian deglaciation. This transition is characterised by a homogenous, 48 cm thick, dark grey, silty clay layer with a distinctive IRD concentration, forming a prominent marker bed for the central Arctic Ocean sediments. The elevated smectite and kaolinite contents in the transitional interval are possible weathering products of the Siberian basaltic rocks, such as the Putorana Plateau, feeding the shelves of the Kara Sea and the western Laptev Sea. The Nd and Sr isotope values are compatible with input from the basaltic rocks and fall within the isotopic range of sediments from these shelves. The abrupt changes in the Nd, Pb and Sr isotopic data from the distinct grey layer attributed to the MIS 4-3 transition likely mark a pronounced deglaciation event. An increase in coarse debris in the grey layer indicates a change in the sedimentation regime with a strong iceberg rafting component. This change may also be related to a sudden release of meltwater from a large ice-dammed lake in the northern Siberia.