Geochemical and isotopic studies of aeolian sediments in China
Geochemical and isotopic studies of aeolian sediments in China
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DOI：
10.1111/j.1365-3091.2004.00618.x
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发表时间：
2004-04-01
期刊：
影响因子：
3.5
通讯作者：
Shimizu, H
中科院分区：
文献类型：
--
作者：
Honda, M;Yabuki, S;Shimizu, H
本文报道了中国几个地区风成黄土和沙漠沙的锶、钕同位素、稀土元素和主量元素组成、矿物组成和粒度组成。这项研究的目的是研究这些风成沉积物的同位素和地球化学特征的区域差异，并对中国黄土的来源进行限制。样本包括来自塔里木和准噶尔盆地的黄土和来自中国西北部塔克拉玛干沙漠的沙漠沙，来自鄂尔多斯地区的黄土和来自中国中北部腾格里沙漠和毛乌素沙漠的沙漠沙，以及来自中国东北部奈曼地区的黄土和沙漠沙。稀土元素在中国黄土沉积物中的分布差异很小，而在沙漠沙中的分布具有区域差异。新的同位素数据记录了黄土和沙漠沙的锶和钕同位素特征的纬度变化。奈曼和准噶尔黄土的锶-87/锶-86比值明显低于塔里木盆地、鄂尔多斯地区和黄土高原的黄土，而epsilon(ND)(0)明显高于塔里木盆地、鄂尔多斯地区和黄土高原的黄土。在沙漠沙中，奈曼样品的epsilon(ND)(0)值高于塔克拉玛干、腾格里和毛乌斯样品。同位素资料表明，黄土高原的黄土来自塔里木盆地黄土和塔克拉玛干沙漠沙，奈曼黄土来自准噶尔盆地黄土。黄土和荒漠沙的纬向变化可能部分是由天山和西昆仑山冰雹的同位素变化所解释的，这可能是黄土和荒漠沙的来源。这些关于黄土和沙漠沙来源的推断与东亚地区的沙尘输送模式是一致的。
The Sr and Nd isotopic, rare earth element (REE) and major element compositions, together with mineral and grain-size proportions, are reported for aeolian loess deposits and desert sands from several Chinese localities. The study was carried out in order to examine regional variations in the isotopic and geochemical features of these aeolian sediments, and to constrain the provenance of Chinese loess. Samples include loesses from the Tarim and Junggar basins and desert sands from the Taklimakan desert in north-west China, loess from the Ordos area and desert sands from the Tengger and Mu-us deserts in north-central China, as well as loess and desert sands from the Naiman area, north-east China. REE distributions show minimal variation among the Chinese loess deposits, whereas those for the desert sands show regional variations. New isotopic data document a latitudinal variation in Sr and Nd isotopic features for the loesses and desert sands. The Naiman and Junggar loesses have distinctly lower Sr-87/Sr-86 ratios and higher epsilon(Nd)(0) values than the loesses from the Tarim Basin, the Ordos area and the Loess Plateau. Among the desert sands, the Naiman samples have higher epsilon(Nd)(0) values than the Taklimakan, Tengger and Mu-us samples. Isotopic data suggest that loesses of the Loess Plateau were supplied from the Tarim Basin loesses and Taklimakan Desert sand, and that the Naiman loesses were supplied from the Junggar Basin loesses. The latitudinal variation in the loesses and desert sands may be partly explained by isotopic variations reported previously for moraines from the Tianshan and west Kunlun Mountains, which are possible sources for the loesses and desert sands. These inferences on the provenance of the loesses and desert sands are consistent with the dust transport pattern over East Asia.