Last 40 ka climate changes as deduced from the lacustrine sediments of Lake Biwa, central Japan

摘要

Sequential changes of aeolian dust and lake primary productivity since the last 40 ka observed in lacustrine sediment core from Lake Biwa, central Japan, and provide high-resolution climate changes in relation to the Asian monsoon activities and the Westerlies in East Asia. Quartz content is very useful as a proxy record for reconstructing aeolian dust changes, influenced by paleointensity of the Asian winter monsoon and the Westerlies since the last glacial. On the other hand, total organic carbon (TOC) and Opal-A contents are useful as a proxy record for reconstructing primary biological production by paleo-precipitation, influenced by paleointensity of the Asian summer monsoon activities. Aeolian dust and TOC records in BIW95-4 core indicated the millennial-scale variation of the Asian winter and summer monsoon activities and the Westerlies during the last 40 ka, suggesting good correlations with global cooling events in the last glacial period found in the North Atlantic region. The Asian summer monsoon activities during the Holocene are frequent and increased at 9, 6, after 2 ka, and decreased at 4 ka.