柴达木地区近三百万年来古气候环境演化的初步研究

PRELIMINARY STUDY ON PALEOCLIMATE AND PALEOEN-VIRONMENT OF THE QAIDUM REGION SINCE THREEMILLION YEARS AGO

本文根据柴达木地区三口钻井岩心的湖相沉积矿物学分析、盐类矿物包裹水及介形类化石δD、δ^(18)O、δ^(13)C等分析,初步建立了长、短时间气候曲线。研究结果表明该地区近300万年来存在着5次较明显的气候冷暖波动,而干湿变化则更趋频繁。推测近5万年来湖泊水体经历了早期的相对稳定蒸发阶段、中期的低温干化阶段、晚期(冰后期)的前5千年在干化的基础上水体复苏和后5千年水体收缩的演化阶段。

Climate is one of the important research subject nowdays. In order to predict the change of climate henceforth, the recovery and rebuilding of ancient climate is a quite important research task. Based on the investigation of sedimentary mineralogy of 602m core, ZK-336 well of Da-langlon, on the investigation of δD, <δ18O of water from primary halite inclusion of 47 m core, ZK-88-0 well of Dabusun Lake, and on the investigation of S18O, δC of ostracoda and trace element of recent sediment from QH-16A core of Qinghai Lake, the climate versus long and short time curve is given in this paper. Preliminary results indicated that the investigation of sedimentary mineralogy of inland sediment, the investigation of δD, 18O of inclusion water, and the investigation of 180,13C of ostracoda can be taken as an efficient means for paleocimate research; the climate of the west China has undergone five fairly clear cold-warm undulation since three million years, the undulations between each durations are obvious; the frequency of dry-wet curve change a bit faster than that of cold-warm curve, there are not clear correspondence relationship betweencold-warm and dry-wet curve. Isotopic research of inclusion water indicated that the low temperature of late glacier was reflected clearly on the composition of water isotope. Based on the data of δ28O,δ13C of ostracoda and analyses of trace elements, the period from recent days to late glacier can be divided into five climate periods' which can compare with the climate divi-.sion of the northern Europe.