SEDIMENTARY ENVIRONMENTAL EVOLUTION DURING LAST DEGLACIATION AND EARLY HOLOCENE IN CHAOHU REGION

Based on the environmental parameters, such as AMS ¹⁴C age, grain size, magnetic susceptibility, geochemical elements, total organic carbon, total nitrogen and organic carbon isotope, extracted from the core sediments of the hole drilled at the Hangbu River Estuary, we reconstructed the environmental evolutionary history for Last Deglaciation and Early Holocene (13 393~7 486 cal.aBP) in Chaohu Region. (1) The region evolved from a cold-dry to a temperate-cool climate during the period from 13 393 to 12 420 cal.aBP and the Chaohu Lake started to develop rapidly with high rainfall and fast rising of lake level, in spite of the cold-and-dry climatic event during 13 040 and 12 773 cal.aBP; (2) The unstable cold and dry paleoclimate during 12 420 and 11 760 cal.aBP with low rainfall and lake level, which is supposed to correspond to the Younger Dryas event, caused the shrinkage and frequent fluctuation of the Chaohu Lake even though the phytoplankton remained survived in the lake; (3) The paleoclimatic environment was mild and humid between 11 760 and 9 160 cal.aBP. With high rainfall and stable lake level, large aquatic plants multiplied in the lake even though there was a cold-and-dry event approximately 11 006 cal.aBP; (4) A warm and dry paleoclimatic environment prevailed between 9 160 and 7 486 cal.aBP with low rainfall and lake level, and the organic matters in the lake were mainly from the phytoplankton. The lake experienced a cold-and-dry event 8 633 cal.aBP. and an anomalous rain-rich event 8 493 cal.aBP.