古尔班通古特沙漠南缘风沙沉积物磁性和化学元素特征及其环境意义  

Magnetic properties and chemical composition of the eolian sediments in southern Gurbantunggut Desert and its environment implications

作　　者：李文 穆桂金[2] 程子娟 谢如梅 陈渠[3] LI Wen;MU Guijin;CHENG Zijuan;XIE Rumei;CHEN Qu(School of Earth Sciences,East China University of Technology,Nanchang 330013;Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi 830011;College of Geography and Environmental Science,Zhejiang Normal University,Jinhua 321004,China)

机构地区：[1]东华理工大学地球科学学院,南昌330013 [2]中国科学院新疆生态与地理研究所,乌鲁木齐830011 [3]浙江师范大学地理与环境科学学院,金华321004

出　　处：《干旱区资源与环境》2024年第8期159-166,共8页Journal of Arid Land Resources and Environment

基　　金：国家自然科学基金(42167063);江西省自然科学基金(20232BAB213067);江西省大学生创新创业训练计划项目(S202310405038,S202310405018)资助。

摘　　要：古尔班通古特沙漠是我国第二大沙漠和重要粉尘源区之一,查明其风沙沉积物的磁性和化学元素特征对于理解粉尘物质循环、气候变化等具有重要价值。文中对该沙漠南缘的一处风成沉积剖面(GEB11)进行了系统的年代、粒度、磁学和地球化学分析,结果显示:GEB11剖面沉积物中主要磁性矿物有磁铁矿、磁赤铁矿和赤铁矿,磁性颗粒以假单畴(PSD)-多畴(MD)为主。地球化学元素组成以SiO_(2)和Al_(2)O_(3)为主,相比UCC,SiO_(2)呈现富集特征,其余元素呈现不同程度亏损。GEB11剖面350cm以上地层沉积物相比350cm以下地层,具有细砂组分含量较高,磁性矿物含量较高且颗粒较粗,SiO_(2)含量较低而Al_(2)O_(3)、Fe_(2)O_(3)、CaO、MgO、Na_(2)O、TiO_(2)含量较高的特点。该剖面沉积物磁性和化学元素特征变化主要受控于风沙活动和风力分选作用,Fe、Ti等元素和磁性矿物主要富集于细砂沉积物。剖面上部发育于小冰期强风沙活动环境下的沉积物具有磁性矿物,Fe、Ti元素和细砂组分含量较高的特点。The Gurbantunggut Desert is the second largest desert in China and is one of the major dust source areas in Central Asia.Determining the magnetic properties and chemical composition of eolian sediments in this desert have important implications for understanding the global climate change and dust material cycles.However,these issues remain highly uncertain.In this paper,we present the results of environmental magnetic,granulometric,geochemical analyses and OSL dating of GEB11 profile from southern Gurbantunggut Desert.The results indicate that the sedimentary magnetic properties are dominated by magnetite and it is mainly present PSD-MD state,the maghemite and haematite are also identified in the sediments of GEB11 profile.SiO_(2)and Al_(2)O_(3)take up a large part of chemical composition.Compared with the average composition of geochemical elements of the upper continental crust(UCC),all elements except SiO_(2)are depleted to a certain degree.Compared to the lower part(700-350cm),the sediments of the upper part(350-0cm)of GEB11 profile are characterized by higher magnetic mineral concentrations,coarser magnetic grain sizes,higher find sand proportion,lower SiO_(2)concentrations and higher Al_(2)O_(3),Fe_(2)O_(3),CaO,MgO,Na_(2)O,TiO_(2)concentrations.The physical weathering process and sedimentary sorting are the major factors influencing the magnetic properties and chemical composition of the sediments of GEB11 profile.The magnetic minerals and some metallic elements(e.g,Fe,Ti)are mainly concentrated within the fine sand that were transported and dispersed by wind.The upper part of this profile was formed during LIA and exhibited higher magnetic mineral concentrations,Fe and Ti concentrations and fine sand proportion which affected by the more intensive and frequent aeolian activity occurred during LIA.

关 键 词：磁性特征 地球化学元素 风力风选 古尔班通古特沙漠 

分 类 号：P59[天文地球—地球化学]