巴丹吉林沙漠湖泊年轻沉积物^(14)C测年初步研究  

A Preliminary Study of AMS ^(14)C Dating of Young Lacustrine Sediments in the Badain Jaran Desert

作　　者：陈天源[1,2] 刘斯文[3] 赖忠平[4] 王振亭[5] 韩凤清[1] 王懿萱[1,2,5] 

机构地区：[1]中国科学院青海盐湖研究所中国科学院盐湖资源综合高效利用重点实验室,青海西宁810008 [2]中国科学院大学,北京100049 [3]国家地质实验测试中心,北京100037 [4]中国地质大学(武汉),湖北武汉430074 [5]中国科学院西北生态环境资源研究院,甘肃兰州730000

出　　处：《盐湖研究》2017年第2期60-66,共7页Journal of Salt Lake Research

基　　金：中国地质科学院基本科研业务费项目(YYWF201525;2015CSJ01);中国科学院仪器功能开发项目(Y410041013)

摘　　要：沙漠湖泊沉积物是研究气候环境变化的珍贵材料,湖泊岩芯年代学研究是重建古气候和古环境的基础和前提,然而其年代的测定存在诸多困难,尤其是年轻湖泊沉积物测年一直是当前地质年代学研究的难题。^(14)C测年作为一种传统的测年方法已被广泛应用于各类湖泊年轻沉积物的年代测定。巴丹吉林沙漠湖泊年轻沉积物能否利用^(14)C方法进行测年,其可靠性如何,需进行研究和验证。选择巴丹吉林沙漠腹地的两支岩芯(BR-1和YD-1),对其进行了^(14)C测年,并与已有的^(210)P_(buns)及其推算年代进行了对比。结果表明:1)沙漠湖泊中的植物残体来源存在较大的随机性,可能是原有的更老沉积层中的植物残体的再沉积,测年结果偏老约1000年。2)湖泊岩芯中有机沉积物样品的年代结果基本符合沉积规律,但受硬水效应的影响,其年代整体偏老400~900年。3)与^(210)P_(buns)年代对比,两种不同测年物质所测得的年代均存在不同程度的偏老现象,表明岩芯所在湖泊^(14)C年龄受多种因素影响,总体存在很大的不确定性。在测年材料极为稀缺的沙漠丘间湖区,利用岩芯中的植物残体、沉积物有机质进行^(14)C测年,可能受老沉积层中测年材料再沉积、湖水碳库效应等因素的影响,^(14)C年代存在诸多不确定性。因此,在对巴丹吉林沙漠丘间湖泊年轻沉积物测年研究过程中应谨慎运用。Lacustrine sediments in the desert provide valuable archives for studying the climate and envi- ronment changes, the research of its chronology is the basis and prerequisite for the reconstruction of pa- leoclimate and paleoenvironment, however, there are lots of difficulties in dating the lacustrine sedi- ments, especially the dating of young lacustrine sediments is a difficult problem in current geochronology. 14C dating, as a kind of traditional dating method, has been widely applied in all kinds of young lacus- trine sediment. Further study and validation of the reliability and applicability of the young lacustrine sed- iments AMS14 C dating in the Badain Jaran Desert are required. Two sediment cores （BR -I＆YD -1 ）in the inter-dune lakes of the Badain Jaran desert hinterland were chosen to make a comparison study be- tween the AMS 14C dating and 21~pb.ns dating. The results show that： （ 1 ） For the great randomness of the source of plant residues in desert lakes or the redeposition of the plant residues which come from the older stratum, the results of plant residues samples are about 1000 years older than what they actually are. （2） The results of organic sediment samples basically conform to the sedimentological law, but affected by the ＂hard water＂ effect, it is 400 - 900 years older than what they actually are. （3） Compared with the re- ／ , suhs of 210pbuns dating, the AMS14C ages of the two materials are older, shows that the AMS14C ages of the lake sediment cores in the Badain Jaran desert are affected by several factors and overall there is a big uncertainty. When the plant residues and the organic sediments which come from the inter-dune lakes of the Badain Jaran desert are used to date, it may be affected by the redeposition of the plant residues which come from the older stratum or the Reservoir Effect. All these factors will lead to a big uncertainty, consequently, more caution should be paid to the AMS14C dating of young lacustrine sediments in the in- ter-dune of Badain

关 键 词：AMS14C测年 碳库效应 210Phuns测年 巴丹吉林沙漠湖泊 

分 类 号：P534.63[天文地球—第四纪地质学]