青藏高原中部色林错中晚全新世以来古气候变化特征  

Paleoclimate changes since Middle-Late Holocene in Selin Co,central Qinghai-Tibetan Plateau

作　　者：宋高 郑绵平[1] SONG Gao;ZHENG Mianping(MNR Key Laboratory of Saline Lake Resources and Environments,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]中国地质科学院矿产资源研究所自然资源部盐湖资源与环境重点实验室,北京100037

出　　处：《地质学报》2022年第7期2272-2280,共9页Acta Geologica Sinica

基　　金：中国地质科学院基本科研业务费项目(编号kk2012)资助的成果。

摘　　要：色林错位于青藏高原中部印度季风和西风环流的过渡地带,同时受西风环流和印度季风系统控制,是研究二者进退变化特征的理想场所。本文利用色林错SL-1钻孔中介形虫Limnocythere inopinata的丰度及其壳体微量元素Mg/Ca和Mn/Ca比值重建了色林错5.3 ka BP以来的古气候环境变化特征。5.3~2.9 ka BP,L.inopinata丰度较小,壳体的低Mg/Ca比值和高Mn/Ca比值表明此阶段气候偏冷湿;2.9~1.8 ka BP,L.inopinata丰度较前一阶段增加,壳体Mg/Ca比值略有增长但仍为低值表明气温虽然有所回升但仍然较低,Mn/Ca比值较前一阶段明显降低,指示湖泊水位下降;1.8 ka BP至今,L.inopinata丰度达到最大,壳体的高Mg/Ca和Mn/Ca比值指示湖泊温度和水位均呈显著的上升趋势。通过与西风区、过渡区以及印度季风区其他湖泊的环境沉积记录对比,本文认为青藏高原中部地区在中全新世晚期主要受西风环流影响,气温较低,西风带来大量水汽使得湖面呈扩张趋势;而到晚全新世西风环流逐渐北撤,色林错受季风影响更大,季风带来的降水和气温升高导致的冰川融水增加与色林错水位上升有密切关系。Selin Co,located at the transitional region of Indian monsoon and westerlies circulation in the central Qinghai-Tibetan Plateau(QTP) and controlled by both,is an ideal place for studying the change characteristics of their advance-retreat history.Based on the abundance and trace elements(Mg/Ca and Mn/Ca) in shells of Limnocythere inopinata,we reconstructed the paleoclimate changes since 5.3 ka BP in Selin Co.5.3~2.9 ka BP,the low abundance and decreased Mg/Ca ratios in shells of L.inopinata indicated cold and humid climate.2.9~1.8 ka BP,the temperature rose slightly implied by the increase of abundance and little rise in Mg/Ca ratio of L.inopinata,but the reduced Mn/Ca ratios indicated that the lake levels kept decrease compared with the previous stage.The abundance of L.inopinata reached the maximum since 1.8 ka BP,the high values of Mg/Ca and Mn/Ca ratios showed the significant increase of temperature and lake levels.Comparing with the sedimentary records of other lakes in westerlies region,transition region and Indian monsoon region,we think that the central QTP was affected by westerlies circulation in the late stage of Middle Holocene,the temperature was low,but the abundant moisture brought by the westerlies made the lake expand,while in the Late Holocene,the westerlies circulation gradually withdrew northward and Selin Co was more affected by the Indian monsoon,the increased lake water level of Selin Co was closely related to the increase in precipitation and glacial-melt water caused by the rise of temperature under the enhancing of the Indian monsoon.

关 键 词：色林错 介形虫 西风环流 印度季风 气候变化 

分 类 号：P534.632[天文地球—第四纪地质学] P532[天文地球—古生物学与地层学]