古尔班通古特沙漠南缘全新世沉积微量元素特征及古环境意义  

Geochemical Characteristics of Trace Elements in Sediments in Holocene at the Southern Edge of the Gurbantunggut Desert and Its Response to Climate Changes

作　　者：张巧文 马运强 李志忠[1] ZHANG Qiaowen;MA Yunqiang;LI Zhizhong(School of Geographical Sciences,Fujian Normal University,Fuzhou 350007,China)

机构地区：[1]福建师范大学地理科学学院,福建福州350007

出　　处：《内蒙古师范大学学报（自然科学汉文版）》2023年第4期382-391,共10页Journal of Inner Mongolia Normal University(Natural Science Edition)

基　　金：国家自然科学基金资助项目(42071011)。

摘　　要：选取古尔班通古特沙漠南缘风积-冲积地层剖面,基于光释光测年建立剖面年代标尺,以微量元素丰度及其比值变化为主要代用指标,结合沉积相和粒度特征,揭示沙漠南缘全新世沉积环境和气候演变过程。结果表明:约11.11~10 ka,各微量元素含量处于低值,反映气候转暖、冰川消融、河流汇入沙漠,但化学风化较弱;约10~6 ka,湖沼沉积发育,各微量元素含量升高,反映该时段化学风化较强,暖湿气候交替偏凉偏干波动;约6 ka至今,各微量元素含量随席状风沙与泥质荒漠交互沉积呈明显波动变化,反映暖湿气候交替偏冷波动。研究区沉积环境和气候演变的阶段性特点,反映了全新世北半球夏季太阳辐射和西风环流的强度变化。此外,天山冰川消融和北大西洋冷事件引发的大气波动也对区域沉积环境变化产生重要影响。The aeolian-alluvial stratigraphic profile in the southern margin of Gurbantunggut desert was taken as the research object to study the evolution process of the environment and climate of the southern margin of the desert.The profile chronology was established by using optically stimulated luminescence(OSL)dating,the changes of the content of trace geochemical element and its ratio were taken as the environmental proxies,and the standardized ratio of element abundance in regional scale and the parameters of sedimentary facies and grain size were measured to analyze the changes of sedimentary environment.The results showed that the changes of sedimentary environment since 11.11 ka in the southern margin of Gurbantunggut Desert were roughly divided into two stages.The first stage was from 11.11 ka to 6 ka,in the early period of the stage(about 11.11~10 ka),the low value of the content of each trace element indicated that the climate at that time was warm,the glacier was melting,rivers penetrated into the desert edge and alluvial deposits developed,but the chemical weathering was very weak;in the late period of the stage(10~6 ka),the content of trace element content was high,the lacustrine facies deposits developed with two layers of clayey silt layers,reflecting the climate at that time was characterized by warm and humid to cool and dry alternation changes.The second stage from 6 ka to present time,the contents of trace elements fluctuated obviously with the alternation of sheet sand and argillaceous desert deposition,indicative of the alternation changes of climate with warm and humid to cold.The phased characteristics of the sedimentary environment and climate evolution in the objective area mainly reflected the intensity changes of the summer solar radiation and the westerlies circulation in the northern hemisphere since the Holocene.Also,the dry and cold climate fluctuations caused by the melting of Tianshan glaciers and the cold events in the North Atlantic had an impact on the changes of the regional sedimen

关 键 词：微量元素 沉积环境 气候变化 沙漠-绿洲过渡带 全新世 

分 类 号：P531[天文地球—古生物学与地层学]