柴达木盆地西台吉乃尔盐湖沉积的年代学研究  

Formation and evolution of the Xitaijinair Salt Lake in Qaidam Basin revealed by chronology

作　　者：王懿萱 陈天源[1,2,3] 吴蝉 赖忠平[5] 郭守栋 丛禄[1,2,3] WANG Yi-xuan;CHEN Tian-yuan;WU Chan;LAI Zhong-ping;GUO Shou-dong;Cong Lu(Northwest Institute of Eco-Environment and Resources, Chinese Academy of Science, Lanzhou 730000, Gansu, China;Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008 , Qinghai, China;University of Chinese Academy of Sciences, Beijing 100049, China;Qinghai Wuyuan Salt Lake Productivity Promotion co. LTD, Xining 810008 , Qinghai, China;School of Earth Sciences, China University of Geosciences, Wuhan 430074, Hubei, China;Qinghai 3 rd Institute of Geo-Mineral Prospecting, Xining 810029, Qinghai, China)

机构地区：[1]中国科学院西北生态环境资源研究院,甘肃兰州730000 [2]中国科学院青海盐湖研究所,青海西宁810008 [3]中国科学院大学,北京100049 [4]青海五元盐湖生产力促进有限公司,青海格尔木816000 [5]中国地质大学(武汉),湖北武汉430074 [6]青海省第三地质矿产勘查院,青海西宁810029

出　　处：《干旱区地理》2019年第4期876-884,共9页Arid Land Geography

基　　金：青海省科技厅攻关项目(2014-GX-Q09);中国科学院战略性先导科技专项(XDA2004010101);国家自然科学基金项目(41671006)

摘　　要：柴达木盆地中部西台吉乃尔盐湖成因及其年代框架还存在争议。通过应用光释光测年法(OSL)和放射性碳测年法(AMS14C)测定两支分别来自该盐湖中部及东部边缘区域的岩芯,获得4个OSL和5个AMS14C年代数据。结果表明:(1)对于老于30 ka的样品放射性碳测年法存在明显的年代低估,而对于年轻样品则存在约4.0 ka的碳库效应,相对而言光释光测年方法具有一定的合理性。(2)两支岩芯顶部粉砂质粘土层形成于约0.3 ka,中部含粉砂质粘土盐层形成于大约4.0 ka,底部粉砂质粘土层则至少形成于70 ka之前。The Xitaijinair Salt Lake,located in the middle of the Qaidam Basin,Qinghai Province,China,is rich in resources of Li,K,B and Mg.For the tremendous economic value,previous studies mainly focused on the hydrology and hydrochemical characteristics of brine.However,the formation and evolution of the salt lake is still controversial and the chronology of the Xitaijinair Salt Lake is absent.In this paper,two cores from the middle and east edge of the salt lake were dated with the methods of Optically Stimulated Luminescence(OSL) and radiocarbon dating(AMS14C),the condition experiments of OSL dating were conducted and the feasibility of the two methods was also discussed.The sedimentary sequence of the two cores showed that the sediments both in the top and bottom are dominated by silty clay,while the middle of the cores are dominated by halite with several layers of silty clay.The sedimentary facies also revealed that the Xitaijinair Salt Lake has been desalted at least twice.Based on 5 AMS14C and 4 OSL chronologies,the chronological framework of the Xitaijinair Salt Lake was preliminary discussed.In the middle of the cores,the OSL dating materials are scarce and only obtained AMS14C chronologies.Thus,we calculated the reservoir effect offset by comparing the OSL chronologies with AMS14C chronologies from the same layer.The ages of silty clay layer from the middle of the cores were obtained by deducting reservoir effect offset from the measured AMS14C ages.The results showed as follows:(1) In AMS14C dating method,samples older than 30 ka were obviously underestimated.While for the younger samples,a^4.0 ka reservoir effect offset was calculated by comparing with the OSL ages.Relatively,the OSL dating results are more reasonable.(2) In both of the two cores,the top silty clay layer was formed about 0.3 ka BP;the silty clay layer in the middle,about 4.0 ka BP,and the bottom silty clay layer,at least 70 ka BP.(3) It seems the Bagayawur anticline in the northeast of the salt lake controlled the formation of the basin,and t

关 键 词：柴达木盆地 西台吉乃尔盐湖 年代学 光释光测年 放射性碳测年 

分 类 号：P512.2[天文地球—地质学] P597.3