Orbital and millennium scale environmental changes in the southern Bering Sea during the last glacial-Holocene: Geochemical and paleontological evidence

The δ18O benthic foraminiferal curve and AMS 14C radiocarbon data provide a representative age model for a southern Bering Sea sediment core (GC-11). Downcore profiles of δ18O of N. pachyderma (s.) and U. auberiana, carbonate and organic carbon contents, species changes in the planktonic foraminifera assemblages and some diatom species show orbital (MIS 1, 2 and 3) and millennium scale variability influenced by the Alaska Current flowing into the studied region. Three warmer episodes in the southern Bering Sea environment were assumed to be synchronous with DO interstadials 8, 12 and 14 (in GISP-2 chronology) during MIS 3. More severe climate and environmental conditions in the southern Bering Sea during MIS 2 occurred synchronously with the LGM within a 17–19 ka time span. Two well pronounced environmental warming events, productivity spikes and changes in the pore water geochemistry, separated by Younger Dryas cooling, were observed at the base of MIS 1 coeval with MWP 1A and 1B. Regional glacial primary productivity based on the calculation of the organic carbon MAR, similar to that found in the far northwestern Pacific, exceeded the Late Holocene values under conditions close to the present day.