Yellow‐brown earth on Quaternary red clay in Langxi County,Anhui Province in subtropical China: Evidence for paleoclimatic change in late Quaternary period |
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Authors: | Xue‐Feng Hu Wei Jiang Wei Ye Ming‐Neng Shen Wei‐Guo Zhang Hong‐Bo Wang Cheng‐Wen Lu Li‐Dong Zhu |
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Institution: | 1. Department of Environmental Science and Engineering, Shanghai University, Shanghai 200072, China;2. Laboratory of Geographical Processes, School of Tourism and Resources Management, Zhejiang Normal University, Jinhua 321004, Zhejiang Province, China;3. Department of Geography, East China Normal University, Shanghai 200062, China;4. Institute of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China;5. College of Territorial Resources and Tourism, Anhui Normal University, Wuhu 241000, Anhui Province, China |
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Abstract: | In order to investigate the paleoclimatic changes in S China during the late Quaternary and their influence on pedogenesis and soil classification, a yellow‐brown earth (YBE)–red clay (RC) profile in Langxi County, Anhui Province was studied. The grain‐size distribution and the major‐ and trace‐element compositions of the profile indicate that the YBE of the profile shares the same origin with the YBE in Jiujiang and Xuancheng and the Xiashu loess in Zhenjiang, and the underlying RC also has aeolian characteristics and shares the same origin with the Xiashu loess. Grain‐size characteristics, molecular ratios of SiO2/Al2O3, SiO2/(Al2O3+Fe2O3), and BA (CaO+MgO+K2O+Na2O]/Al2O3) and other weathering indices (CaO/TiO2, MgO/TiO2, K2O/TiO2, Na2O/TiO2, and Rb/Sr) of the profile indicate that the RC is more strongly weathered than the YBE. Magnetic susceptibility (χlf) of the uniform red clay (URC) of the profile is significantly enhanced. However, that of the underlying reticulate red clay (RRC) is significantly decreased because of the paleogroundwater movement and cannot indicate its strong weathering properties. The YBE‐RC profile in Langxi County recorded a great climatic change during late Quaternary: At that time, the pedogenic development of the RC was terminated and widespread dust deposition occurred. The parent material of the RC may be aeolian deposits which were accumulated before the last interglacial and were strongly weathered and rubified under the subsequent interglacial climate. It is observed that red soils, derived from the RC, and yellow‐brown soils, derived from the YBE, coexist in the study area, which is contradictive to the theory of the zonal distribution of soils. Therefore, it is necessary to take into account the history of Quaternary climatic changes when studying pedogenesis. |
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Keywords: | red clay (RC) paleoclimatic changes weathering indices magnetic susceptibility (χ lf) zonal distribution of soils |
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