Basin-scale seawater lead isotopic character and its geological evolution indicated by Fe-Mn deposits in the SCS |
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| Authors: | Xiaoxia Tu Chonghui Wang Qunhui Yang Benduo Zhu |
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| Institution: | 1. School of Ocean and Earth Science, Tongji University, Shanghai, China;2. College of Biological &3. Environmental Sciences, Zhejiang Wanli University, Ningbo, China;4. Ministry of Land and Resources, Key Laboratory of Marine Mineral Resources, Guangzhou, China;5. Guangzhou Marine Geological Survey, China, Geological Surve, Guangzhou, China |
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| Abstract: | AbstractThe geochemical characteristics and Pb isotope variations in Fe-Mn deposits collected from the South China Sea (SCS) were studied in this paper. The mineralogical and chemical composition data indicate that the deposits are almost all hydrogenetic in origin. Compared with the Fe-Mn deposits in other oceans, the SCS Fe-Mn deposits have a significantly higher Pb content because of higher material supply in addition to a lower growth rate of the deposits. Pb isotope ratios in the surface of the SCS Fe-Mn deposits are relatively uniform, with a characteristic of relatively lower 206Pb/204Pb ratio. The Pb isotopic compositions of the SCS Fe-Mn deposits are controlled by the Pacific Deep Water and local inputs, which include eolian dust from the Asian continent and weathering products from Taiwan, Luzon and SCS submarine volcanic rocks. The continuously increasing 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios along the transect of nodule D581 over the past 3.5?Ma are affected by the stepwise closure of the Luzon Strait that reduced volcanic material supply and the deep current strengthen at the same time. |
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| Keywords: | Pb isotopes Fe-Mn deposits South China Sea hydrogenetic Luzon Strait |
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