Palaeoenvironment and palaeoclimate evolution of Northeast China: Based on multi-proxy analysis of sediment from Lake Xingkai

Abstract

A multi-proxy analysis that included magnetic susceptibility, grain size, organic carbon isotope composition (δ13Corg), organic nitrogen isotope composition (δ15Norg), total organic carbon (TOC), total nitrogen (TN), carbon-to-nitrogen ratio (C/N) and redness analyses was conducted on a 269-cm long sediment core collected from Lake Xingkai to reconstruct the palaeoclimate and palaeoenvironment evolution of Northeast China since 28 ka BP. The analysis results showed that during the period between 27,740 and 25,540 cal a BP, the lake was at a low level and in a cold and dry climate period. During the period between 25,540 and 23,650 cal a BP, precipitation increased compared to the previous period, but the lake level was still relatively low, and the lake region was in a cold and wet climate period. During the period between 23,650 and 19,940 cal a BP, the climate in the lake region was cold and dry, and this period corresponded to the LGM (Last Glacial Maximum). During the period between 19,940 and 14,510 cal a BP, the precipitation increased compared to the previous period and temperature also increased to some extent. During the period between 14,510 and 11,500 cal a BP, the late glacial period, the climate changed from warm and wet to cold and dry, and the lake region was in a Bølling/Older Dryas/Allerød/Younger Dryas climate fluctuation period. During the period between 11,500 and 2,800 cal a BP, the Holocene warm period, and between approximately 8,000 and 5,000 cal a BP, the study region entered the Holocene climate optimum period. After 2,800 cal a BP, the lake level decreased significantly and the climate turned cool and dry. After 1,000 cal a BP, change of sediment grain size composition and magnetic susceptibility, increasing of secondary arborescent pollen in pollen assemblages, which reflects the influence of human activity.