Millennial-scale variability of marine productivity and terrigenous matter supply in the western Bering Sea over the past 180 kyr
1Helmholtz Centre for Ocean Research Kiel (GEOMAR), Wischhofstr. 1-3, 24148 Kiel, Germany
2Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
3Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, Baltiskaya St. 43, 690041 Vladivostok, Russia
4North Eastern Interdisciplinary Science Research Institute (NEISRI), Far Eastern Branch, Russian Academy of Sciences, Portovaya St. 16, 685000 Magadan, Russia
*now at: Department of Ocean Floor Geoscience, Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
Abstract. We used piston cores recovered in the western Bering Sea to reconstruct millennial-scale changes in marine productivity and terrigenous matter supply over the past ~180 kyr. Based on a geochemical multi-proxy approach our results indicate closely interacting processes controlling marine productivity and terrigenous matter supply comparable to the situation in the Okhotsk Sea. Overall, terrigenous inputs were high, whereas primary production was low. Minor increases in marine productivity occurred during warm intervals of stage 5 and interstadials, but pronounced maxima were recorded during interglacials and Termination I. Seasonal sea-ice is suggested to act as the dominant transport agent for terrigenous material. From our results we propose glacial, deglacial, and interglacial scenarios for environmental change in the Bering Sea. These changes seem to be primarily controlled by insolation and sea-level forcing which affect the strength of atmospheric pressure systems and sea-ice growth. The opening history of the Bering Strait and the Aleutian passes is considered to have had an additional impact. Sea-ice dynamics are thought to drive changes in surface productivity, terrigenous inputs, and upper-ocean stratification. High-resolution core logging data (color b*, XRF scans) strongly correspond to the Dansgaard–Oeschger climate variability registered in the NGRIP ice core and support an atmospheric coupling mechanism of Northern Hemisphere climates.