Magnetic properties of surface soils across the southern Tarim Basin and their relationship with climate and source materials |
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Authors: | JinBo Zan XiaoMin Fang JunSheng Nie ShengLi Yang ChunHui Song Shuang Dai |
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Institution: | (1) Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, P.O. Box 9825, 100029 Beijing, People’s Republic of China;(2) Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 830011 Urumqi, China;(3) Academy of Exploration and Development, Northwest Company, SINOPEC, 830011 Urumqi, China |
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Abstract: | The magnetic susceptibility (χ) of surface soils on the Chinese Loess Plateau (CLP) has strong positive correlation with mean annual precipitation. It is
widely accepted that ultrafine magnetite/maghemite grains produced during pedogenesis are responsible for the enhancement
of χ, and loess χ on the CLP has been widely used as a proxy for the intensity of the East Asian summer monsoon. However, few works have investigated
mechanisms for the enhancement of χ in the case of surface aeolian sediments in westerly-dominated inland China, north of the Tibetan Plateau. Here detailed
rock magnetism and grain size studies of 49 surface samples taken across the southern Tarim Basin for different rainfall/temperature/altitude
conditions are presented. The results show that samples taken from desert have the lowest χ values and that χ of loessic sand and loess samples decreases with increasing altitude. In addition, the rock magnetism studies suggest that
the magnetic properties of surface soils across the southern Tarim Basin are mainly controlled by the concentration of coarse
aeolian ferrimagnetic minerals. The contribution of ultrafine pedogenically produced magnetic grains to χ is very limited. |
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Keywords: | surface soils magnetic susceptibility grain size Tarim Basin rock magnetism |
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