Wind-blown origin of the Pliocene red clay formation in the central Loess Plateau, China
Wind-blown origin of the Pliocene red clay formation in the central Loess Plateau, China
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DOI：
10.1016/s0012-821x(98)00145-9
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发表时间：
1998-09-01
影响因子：
5.3
通讯作者：
Guo, B
中科院分区：
文献类型：
--
作者：
Ding, ZL;Sun, JM;Guo, B
为了确定中国黄土高原上新世红粘土地层的沉积过程，对4个400多公里的红粘土剖面进行了研究。剖面上密布样品的粒度分析表明，红粘土颗粒非常细小，砂粒含量(>；63µm)可以忽略不计，反映不同粒度参数变化的所有曲线都具有相似的模式。4个剖面上部的粒度记录与以4~8亩为中心的中值粒度基本一致，佳县红粘土剖面28个样品的稀土配分模式均具有轻稀土富集、重稀土相对平坦和轻微的Eu负异常特征，与风成黄土和平均上陆壳的稀土配分模式相似。这些证据表明，红色粘土沉积物是被风吹来的。因此，中国黄土高原2.6 Ma以来黄土-土壤序列的积累可以看作是上新世大气尘埃沉积的延续。对黄土高原风成红粘土的空间粒度变化的观测表明，风成红粘土可能主要由西风带输送，与上覆黄土主要由东亚冬季季风风输送有明显不同。(C)1998 Elsevier Science B.V.保留所有权利。
In order to determine the depositional processes of the Pliocene red clay formation deposited directly beneath the Plio-Pleistocene loess in the Chinese Loess Plateau, four red clay sections spanning over 400 km are studied. Grain size analysis of closely spaced samples in the sections shows that the particles of the red clay are very fine with the sand fraction (>63 mu m) being negligible, and that all the curves indicating changes in different grain size parameters have a similar pattern. The grain size records in the upper part of the four sections are almost identical with the median grain size centered at 4-8 mu m. The REE patterns of 28 samples from the Jiaxian red clay section are all characterized by LREE enrichments, relatively flat HREE and slight negative Eu anomaly, being similar to those of eolian loess and the average upper continental crust. These lines of evidence point to a wind-blown origin of the red clay deposits. Accumulation of the loess-soil sequences in the Chinese Loess Plateau during the past 2.6 Ma can be therefore regarded as the continuation of the Pliocene atmospheric dust deposition. Observations of spatial grain size changes in the Loess Plateau suggest that the eolian red clay might be transported mainly by the westerlies, differing significantly from the overlying loess that was transported essentially by the East-Asia winter monsoonal winds. (C) 1998 Elsevier Science B.V. All rights reserved.