Characteristics of Grain Size Composition Holocene Deposits and Its Paleoclimatic Significance in Mu Us Sandy Land

CAO Hong-xia; ZHANG Yun-xiang; YUE Le-ping; WANG Yi

The analytic consequences show the changing laws of grain size and regional magn etic susceptibility in Mu Us sandy land, the grain size gradually becomes smalle r, while the magnetic susceptibility becomes larger from north to sout h. This phenomenon appears not only on the surface of Mu Us, but also obviously occurs on the same layer of different places, so it shows that Mu Us sandy la nd's forming process is closely related to the East Asian monsoon. According to the analyses from selected profiles, we know that, it is cold and dry in this re gion during the later Pleistocene, and early Holocene East Asian winter monsoon' s influence is obvious, so, it is a period of sand accumulation, when the layer s become thinner gradually from north to south. During Middle Holocene, it is wa rm and humid, influenced evidently by East Asian summer monsoon, so, it is an ob vious pedogenesis, when there are generally well-developed Holecene palaeosol( S0) from north to south, and the pedogenesis in the south is better than that in the north, the soil is also thicker than that in the north. From late Holocene to present, the climate changes tend to be dry and cold, but its changing exten t is smaller than that of last glacial period.

1. Laboratory of Continental Dynamics of Department of Education, Northwest Un iversity Department of Geology, Xi'an 710069;

2. Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710075;

3. Exploration Institute in Xianyang, Xianyang Shaanxi 712000

Received Date: 2002-07-24

Rev Recd Date: 2002-11-11

Publish Date: 2003-09-10

Key words:

Abstract: The analytic consequences show the changing laws of grain size and regional magn etic susceptibility in Mu Us sandy land, the grain size gradually becomes smalle r, while the magnetic susceptibility becomes larger from north to sout h. This phenomenon appears not only on the surface of Mu Us, but also obviously occurs on the same layer of different places, so it shows that Mu Us sandy la nd's forming process is closely related to the East Asian monsoon. According to the analyses from selected profiles, we know that, it is cold and dry in this re gion during the later Pleistocene, and early Holocene East Asian winter monsoon' s influence is obvious, so, it is a period of sand accumulation, when the layer s become thinner gradually from north to south. During Middle Holocene, it is wa rm and humid, influenced evidently by East Asian summer monsoon, so, it is an ob vious pedogenesis, when there are generally well-developed Holecene palaeosol( S0) from north to south, and the pedogenesis in the south is better than that in the north, the soil is also thicker than that in the north. From late Holocene to present, the climate changes tend to be dry and cold, but its changing exten t is smaller than that of last glacial period.

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Reference (10)

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Characteristics of Grain Size Composition Holocene Deposits and Its Paleoclimatic Significance in Mu Us Sandy Land

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