Research Of High Resolution Climate Change During Holocene In Cuoqin, Tibet

Nowadays, more and more climatic issues are threatening human existence and sustainable development of society. It is important to explore the rule of climate evolvement in different timescales, reveal the reason of climate change, and predict the state of climate in the future. To reveal the trend of climate change in the future, we must fully understand the rule of climate evolvement in the past. Climate change in Qinghai-Tibet Plateau during Holocene, especially the impact of plateau uplift on Asian monsoon, becomes the research hotspot. The study of climate change in the hinterland of Qinghai-Tibet Plateau is one the most important parts. Therefore, lacustrine deposits of Cuoqin Area which locate in the hinterland of Qinghai-Tibet Plateau are typical. We get samples every 10 cm on the section, establish the age framework through AMS14C dating method, and reveal the climate change in Cuoqin Area during Holocene through the analysis of several proxies (grain-size, TOC, TOC/TN, and organic carbon isotope). And discuss the mechanism through comparing the main grain-size curve with the stalagmite oxygen isotope of Dongge Cave. It can be concluded as follows:1 Through AMS14C dating method, the age of Cuoqin Section is 11.8 kyr BP ~ 3.4 kyr BP.2 Besides the precipitation and temperature, the concentration of CO2 in the atmosphere is one of the important factors which control the change of the organic carbon isotope values of lacustrine deposits in Cuoqin area.3 Through the analysis of each proxy, the climate change during 11.8 kyr BP ~ 3.4 kyr BP can be divided into 3 stages:(1) 11.8 kyr BP ~ 7.4 kyr BP. Precipitation is fluctuant but high. The lake level is highest in the entire evolutive process. Emergent plants decrease, and the submerged plants increase. The climate is humid and warm. (2) 7.4 kyr BP ~ 5.2 kyr BP. Precipitation is decreasing. The lake level is falling. Emergent plants relatively increase, and the submerged plants decrease. Climate change cold and arid.(3) 5.2 kyr BP ~ 3.4 kyr BP. Precipitation and temperature oscillate in this stage. Climate is instable, but don't show trend. It might be warmer and humider than last stage, but still arid and cold.4 The main grain-size record of Cuoqin section deposits is consistent with the records of stalagmite oxygen isotope of Dongge Cave and deep-sea sediments of North Atlantic. This implies that the climate changes shown in those records are forced by same factors, including solar output, circulation of atmosphere and ocean, etc. Although Qinghai-Tibet Plateau is an unattached geographic and geomorphologic cell, the hinterland still correlates well with global climate change.