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Geochimica木虫 (正式写手)
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【原创】简评Li et al., GEOLOGY, August 2009
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Loess depositions in central China: Where do they come from? The Chinese Loess Plateau located in central China has been covered by thick loess sedimentations (> 100 m). The loess is thought to be the consequences of Asian dust settlement which had been transported by wind from the vast arid regions in far north or west. However, the exact location of where the loess material comes from is poorly constrained. Distinguishing different sources for Asian dust and deciphering the origin of ancient dust deposition – the Chinese loess – would help us better understand the history of Asian dust production and transportation, which would have profound paleoecology and paleoclimate implications. Gaojun Li and colleagues at Nanjing University employed paired radiogenic isotope analyses, Neodymium (Nd) and Strontium (Sr), to survey all major deserts or arid lands in China which could serve as potential dust sources. They classified those deserts into three different areas with disparate isotopic signatures. Since Nd-Sr isotopes are resistant to alterations during dust production and transportation processes, Li et al. argue that the Nd-Sr isotope analyses of both ancient (loess) and modern dust deposition could help answering the question: where do they come from? Application of this technique to Chinese loess reveals that instead of the closest deserts on the Ordos Plateau, their origin relies in the northern margin of the Tibetan Plateau thousands of kilometers away. Journal Reference: Natural and anthropogenic sources of East Asian dust Gaojun Li, Jun Chen, Junfeng Ji, Jiedong Yang, and Tim M. Conway http://bbs.nju.edu.cn/file/Earth ... st_Geology_2009.pdf |
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