Millennial scale cycles in the Bering Sea during penultimate and last glacials; their similarities and differences

摘要

The age model of the western Bering Sea core 85 KL was modified through correlation of new and earlier-measured productivity proxies with the Chinese interstadials described by delta O-18 records of Hulu and Sanbao caves and the relative paleointensity events in the studied core with those in the dated records. Resulted sequence of millennial scale Bering Sea Interstadials recorded by abrupt productivity risings was established during the penultimate glacial consistently with the Chinese interstadials and Antarctica isotope maxima. The pattern of the frequency and amplitude of the millennial productivity/climate variability in the Bering Sea during the penultimate glacial resembles that initially depicted in the delta O-18 of Chinese cave stalagmites and is quite similar to one of the Dansgaard-Oeschger cycles during last glacial, except for their terminations. Contrary to well-pronounced interstadial A.1 during termination TI, an interstadial B.1 over the TII has lower duration and therefore is weakly observed in Antarctic temperature changes. Our results provide robust evidence that the bipolar seesaw mechanisms of millennial climate changes in the Northern and Southern Hemispheres were similar during the last and penultimate glacials.