1319 / 2019-08-09 12:09:45

Climate change recorded by Hala Lake in the northeastern Tibetan Plateau since the last deglaciation

1、第四纪地质与全球变化 > 专题5：晚更新世—全新世东亚环境演变记录

The study on climate change in the northeastern Tibetan Plateau (NETP) is helpful to understand the evolution of Indian summer monsoon (ISM) and East Asian summer monsoon (EASM). However, the climate change in the NETP and corresponding hydrothermal configuration since the last deglaciation (especially the Holocene) are still in debate. Here, several proxies from Hala Lake sediments including chironomids, loss-on-ignition, grain size and X-ray fluorescence were used to explore the paleoclimate change in the NETP. They documented a series of climate events during the deglaciation, such as Heinrich Event 1 (H1) and Younger Dryas (YD) Event which were characterized by cold-dry climate and strong physical weathering, and Bølling-Allerød (BA) Event which was characterized by warm-wet climate and weak chemical weathering. Furthermore, there records also indicate the megathermal and maximum precipitation/moisture, high lake level and strong chemical weathering in the NETP during the period of ca. 10-6.8 ka (1 ka=1000 cal yr BP). The maximum precipitation/moisture during the early-Holocene and early mid-Holocene in both Hala Lake basin and typical ISM regions suggest that the climate change in Hala Lake was controlled by ISM at the time, which is different from the early and mid-Holocene (ca. 10-5 ka) maximum precipitation/moisture in Qinghai Lake and surrounding area. This contradiction could be reconciled by our propose that the mid-Holocene strong EASM can influence Qinghai Lake basin but could not reach the higher-altitude Hala Lake basin with the decline of influence of ISM on the NETP. In addition, it is notably that low Rb/Sr ratios during H1 and early-Holocene and early mid-Holocene represent strong physical weathering and strong chemical weathering, respectively, indicating that the significance of Rb/Sr ratio from lake sediments might shift between different climate states.