CAJ | 학술논문

通过对库姆塔格沙漠地表沉积物样品进行重矿物和主量元素分析,获得了其矿物和元素组成特征:矿物种类多,绿帘石和角闪石含量为主;化学组成上以Si、Al为主,和上陆壳平均化学组成相比,除Si、Ca外都有一定的亏损,Fe、Mg、Ca、P、Ti、Mn等元素的变异系数较高.库姆塔格沙漠地表沙物质组成特征与阿尔金山北麓出露的岩石和冲、洪积扇物质组成基本一致,与塔克拉玛干沙漠也有很大的共性,反映了库姆塔格沙漠地表沙物质卡要来源于阿尔金山.沙漠北区强烈的东北风将阿奇克谷地和疏勒河下游的河湖相沉积物搬运至沙漠腹地,构成另一个重要的沙物质来源.A-CN-K图解揭示了库姆塔格沙漠地表物质化学风化程度很低,处于较弱的去Na、Ca阶段,其他元素未发生明显的化学风化或迁移;A-CNK-FM图解表明,库姆塔格沙漠地表物质在搬运、沉积过程中Fe、Mg等元素发生显著分异,其原因主要是铁镁质矿物由于磨损、分选作用遭破碎和风化,使粒度较粗的沙漠沙Fe、Mg等元素相对亏损.
통과대고모탑격사막지표침적물양품진행중광물화주량원소분석,획득료기광물화원소조성특정:광물충류다,록렴석화각섬석함량위주;화학조성상이Si、Al위주,화상륙각평균화학조성상비,제Si、Ca외도유일정적우손,Fe、Mg、Ca、P、Ti、Mn등원소적변이계수교고.고모탑격사막지표사물질조성특정여아이금산북록출로적암석화충、홍적선물질조성기본일치,여탑극랍마간사막야유흔대적공성,반영료고모탑격사막지표사물질잡요래원우아이금산.사막북구강렬적동북풍장아기극곡지화소륵하하유적하호상침적물반운지사막복지,구성령일개중요적사물질래원.A-CN-K도해게시료고모탑격사막지표물질화학풍화정도흔저,처우교약적거Na、Ca계단,기타원소미발생명현적화학풍화혹천이;A-CNK-FM도해표명,고모탑격사막지표물질재반운、침적과정중Fe、Mg등원소발생현저분이,기원인주요시철미질광물유우마손、분선작용조파쇄화풍화,사립도교조적사막사Fe、Mg등원소상대우손.
The Kumtagh Desert is one of the eight biggest deserts in China.In this study,33 representative surface sediment samples were collected from Kumtagh Desert and analyzed in the laboratory to obtain composition of heavy mineral and content of geochemical elements.Results show that there are various kinds of heavy minerals in these samples,with large content of epidote and hornblende.Si and Al 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 Si and Ca are depleted to a certain degree;Fe,Mg,Ca,P,Ti and Mn have high coefficients in their contents.Mineral composition of the samples of the Kumtagh Desert has a similarity with that of rocks of Altyn Tagh,surface sediments of the alluvial/fluvial fans of the Aityn Tagh and that of the Taklamakan Desert,indicating that one major source of the Kumtagh Desert sediments is located in Altyn Tagh.Alluvial deposits and lake sediments in Aqik valley and lower reaches of the Sule River are prone to be eroded and transported by the strong northeasterly wind to the Kumtagh Desert,as a result these places form another source of surface deposits of the Kumtagh Desert.A-CN-K ternary diagram shows that a weak chemical weathering by loss of Na and K occurred in these sediments,while other geochemical elements was in a less weathering or leaching process.A-CNK-FM temary diagram suggests that Fe and Mg have distinct chemical differentiation.Physical weathering process makes it easy for marie minerals to be eroded and enriched in fine particles,thus coarse desert sand particles can be relatively depleted in Fe and Mg.Mineral and geochemical composition of sediments in arid regions with less chemical weathering are mostly effected by physical processes.