古尔班通古特沙漠不同粒级沉积物中稀土元素分布特征及其制约因素  

Distribution Characteristics and Restriction Factors of Rare Earth Elements in the Size-differentiated Sediments from Gurbantunggut Desert

作　　者：刘秀帆 张峰[1] LIU Xiu-fan;ZHANG Feng(Key Laboratory of Oasis Ecology,College of Resource and Environmental Science,Xinjiang University,Urumqi 830046,China)

机构地区：[1]新疆大学资源与环境科学学院绿洲生态教育部重点实验室,新疆乌鲁木齐830046

出　　处：《稀土》2021年第4期63-70,共8页Chinese Rare Earths

基　　金：国家科技基础资源调查专项(2017FY101004);国家自然科学基金新疆联合基金(U1503381)。

摘　　要：古尔班通古特沙漠是周围山脉沉积物的"汇"。为研究沙漠沉积物稀土元素(REE)的"粒度效应"及其制约因素,采集了古尔班通古特沙漠不同位置的沉积物3件,测定了粒度并分析了各粒级的稀土元素含量。结果表明,沙漠东部样品粒度最粗,西北部次之,南部最细;样品稀土元素总量(∑REE)最大值均出现于<63μm的粒级,东部样品∑REE含量最高(1164.17×10^(-6)),西北部样品居中(783.04×10^(-6)),南部样品最低(754.92×10^(-6))。稀土元素球粒陨石标准化模式表现出斜"L"型分布,与塔克拉玛干沙漠、巴丹吉林沙漠、库布齐沙漠和毛乌素沙地基本相同;样品轻重稀土分异明显,轻稀土占据绝对优势;样品Eu负异常明显且主要发生于细颗粒,Ce无明显异常。通过对REE参数的分析认为,各粒级沉积物REE含量的不同主要受控于各粒级样品矿物成分的差异,黏土和细沙中REE含量高的原因是黏土矿物对REE的吸附作用相对较强,而粗颗粒样品REE含量较少则缘于石英和长石的稀释作用。本研究揭示了古尔班通古特沙漠不同粒级沉积物REE含量差异及其影响因素,为REE应用于该沙漠沉积物的示踪研究提供了依据。Gurbantunggut desert is the "sink"of the surrounding mountains. In order to study the "granularity effect"and restriction factor of rare earth elements(REE), this work including collecting samples in different location, grain size analysis and REE contents examination among different particle size fraction has been carried out. The results show: the samples in the east were the coarsest, in the northwest the second, and in the south the fine-grain. The maximum total REE contents(∑REE) of the three samples all occurred in the fraction of <63 μm, the content of the eastern samples was the highest(1164.17×10^(-6)), the northwest samples was in the middle(783.04×10^(-6)), and the southern samples was the lowest(754.92×10^(-6)).The REE chondrite-normalized distribution patterns of all samples are similar to those of Taklamakan desert, Badain Jaran desert, Kubuqi desert and Maowusu Sandy Land, showing an oblique "L" type distribution with obvious differences in LREE and HREE, and LREE absolutely dominating in the total REE contents. Eu negative anomaly was obvious and mainly appeared in fine particles, while Ce anomaly was not obvious. Based on REE parameters, the REE contents difference among different grain size fractions is mainly controlled by the change of the mineral composition in sized-differentiated sediments, the high REE contents in clay and fine sand sediment result from the adsorption by clay and fine sand sediments, but the REE content in the coarse grain is less which is because of the dilution effect of quartz and feldspar.This study revealed the REE content differences and its influencing factors in sediments of sized-differentiated fractions in Gurbantunggut desert, and provided evidence for the application of REE in the provenance study of the desert.

关 键 词：古尔班通古特沙漠 不同粒级沉积物 稀土元素 矿物 

分 类 号：P595[天文地球—地球化学]