Sedimentary characteristtxcs of zk91-2 core and climate-environment evolution of Zabuye Lake, Tibet Plateau

扎布耶盐湖位于西藏高原腹地,1991年在其南部干盐滩中钻取了20m深湖相沉积,以5~10cm/个的密度进行高分辨率取样,详细探讨了沉积标志、矿物组合(尤其Mg、Ca、Li碳酸盐)、干旱与潮湿两种气候类型的元素组合等气候环境指标,推导了晚更新世以来该湖区湖面涨缩、水质咸谈及气温高低变化。;Zabuye saline lake is situated in the hinterland of Tibet Plateau. In 1991, a core of 20m was drilled up in the southern lake, and 5~10-cm-lorg sampler taken in succession. Valuable studies were performed on the climate-environmental indicator of sedimentary marks, mineral association, and element assemblage, etc. Sedimentary structure, size distribution, and organic materials etc. clearly revealed the fluctuation of water depth and air temperature, and it was consistent with the variation of content of dolomite and calcite. We have also paid special attention to Li-bearing carbonate, borate and mirabilite etc. which are sensitive to salinity and temperature of the lake water and exist commonly in salt lake sediments in Tibet Plateau. Cluster analysis of some elements (Ca, Mg, Sr, K, Na, B, Ba, Li, Fe, Mn, Cr, Co, Ni, V, Ci) in the sediments shows that they can be distinguished into twc parts:some elements (Ca, Mg, Sr, K, Na, B, Li, Ba) accumulate in the sediment during arid period an arid type, and the others concentrate in the sediments during humid period a humid type. It is found that the ratio of the arid type to the humid type is a better indicator of the climate for the sediments in geological era. The study shows that before 2.9×104 a B-P., the old Zabuye Lake was deep and had a vast area, the climate then was cold and a little humid; during 2.9×104~2.2×104a B. P., the climate of the lake area turned warm and humid; from 2.O×104 a B. P. onwards, the climate became dry and cold, the lake water dropped greatly and got salinized; but during 1.3×104~1, 1×104 a B, P., there existed a warm and humid period; from Holocene Epoch onwards, some soluble salt began to deposit, during 6000~4000 a B. P. 5 there was an obvious fluctuation to warm and humid; from then on, the climate was getting dryer and colder.