阿拉善地区湖泊岩芯磁性特征记录的全新世环境变化  

Holocene Environmental Change Recorded by Core Magnetic Properties of Juyan Lake,Northwestern China

作　　者：刘宇航[1] 夏敦胜[1,2] 金明[1] 张俊辉[1] 

机构地区：[1]兰州大学西部环境与气候变化研究院,甘肃兰州730000 [2]中国科学院寒区旱区环境与工程研究所,甘肃兰州730000

出　　处：《中国沙漠》2012年第4期929-937,共9页Journal of Desert Research

基　　金：国家自然科学基金项目(40871090和41071125);国家重点基础研究发展计划"973"项目(2010CB950204)资助

摘　　要：对居延海G36钻孔进行了系统磁性特征分析,并结合总有机碳含量和粒度等环境代用指标,在精确测年的基础上,探讨了居延海地区全新世时期以来的环境变化。结果显示,居延海岩芯磁性矿物主要存在于粗颗粒的沉积物中,载磁矿物为颗粒较粗的多畴磁铁矿;磁化率变化机制比较复杂,与干湿环境变化没有简单正(反)关系。根据G36沉积物环境代用指标的变化,大致可以将其分为4个干湿交替时期:6 700～4 600aBP干旱时期,4 600～3 100aBP湿润时期,3 100～2 500aBP干旱时期以及1 800aBP以来湖泊干涸。在这4个时期中,磁学参数记录了两次显著湿润事件和两次显著干旱事件。The Holocene environmental change of Juyan Lake in northwestern China was studied through combination of analyzing magnetic parameters of lacustrine core from G36 drilling hole in Juyan Lake,investigating total organic carbon content and grain size and other environmental proxies,and precisely AMS14C dating.Results show that most magnetic carrier minerals appeared in coarse sediments and the main magnetic minerals are contained in coarse multi-domain magnetite particles.The change mechanism of magnetic susceptibility is complicated and there is no simple positive or negative relationship between magnetic susceptibility change and environmental arid-wet change.Analysis of environmental proxies showed that the Holocene environmental changes of Juyan Lake could be divided into four arid-wet alternating periods： arid period in 6 700~4 600 a BP,wet period in 4 600~3 100 a BP,arid period in 3 100~2 500 a BP,and the lake drying up period since 1 800 a BP.In this four periods,two significant wet events and two outstanding arid events are recorded by magnetic parameters.

关 键 词：全新世 环境磁学 居延海 阿拉善 

分 类 号：P532[天文地球—古生物学与地层学]