The Climate Evolution Of Jilantai Salt Lake During The Last13800Years

Studying on characteristics of climatic and environmental evolution overgeological period in arid region can not only help us understand the aridificationprocess, but also provide a scientific basis for construction of ecological environmentin western China．Jilantai Salt Lake lies in edge of the monsoon areas, which arefacing fragile ecology because of the dry climate. Based on the AMS14C dating andsemi-quantitative mineralogical analysis by XRD of a787-cm-long sediment core(core JLTL－2010) of Jilantai Salt Lake, evolutionary process of Jilantai Salt Lakeand its response to climatic change during the last13800years were rebuilt, the resultsshowed that:(1)13.8－11.7cal ka BP, water in Jilantai Salt Lake was slightly salty, andthe lake enjoyed a relatively humid climate.(2)11.7－10.2cal ka BP, the lake began toshrink and salinize, entering its saltwater lake stage, and the climate exhibiting muchdrought trend.(3)10.2－5.5cal ka BP, Jilantai Salt Lake was in a sulfate depositionalstage, though it had experienced a significant desalination process, when the climatewas dominated by a continuous drought overall this stage.(4)5.5－0cal ka BP, thesalification process further strengthened during this stage, from the early sulfatedeposition into chloride deposition, and achieved full-scale chloride deposition during3.7－2cal ka BP. A short and obvious desalination process occurred during2－1.7calka BP, but saline minerals were still composed by halite. And the drought was furtherintensified during this stage. On the whole, the formation of salt minerals in JilantaiSalt Lake occurred on the background of the Holocene warming, and continued tilltoday, especially separating out of a large number of mineral salts since the middleand late Holocene. Solar radiation began to reach extreme values in the Holocene andthis was synchronous with the Jilantai Salt Lake began to dry, which may indicate thatthe solar radiation had certain influence on drying of the Jilantai Salt Lake. In addition,the further intensified drought condition in the middle and late Holocene was synchronous with advance and retreat of the Asian Monsoon, indicating that theweakened summer Asian monsoon may have aggravated degree of drought in JilantaiSalt Lake area．...