In Situ Analyses of Trace Elements,U–Pb and Lu–Hf Isotopes in Zircons from the Tongshankou Granodiorite Porphyry in Southeast Hubei Province,Middle-Lower Yangtze River Metallogenic Belt,China |
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作者姓名: | XIA Jinlong HUANG Guicheng DING Lixue CHENG Shunbo |
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作者单位: | 1 Wuhan Center, China Geological Survey, Wuhan 430205, Hubei, China
2 Research?Center?of?Granitaic?Diagenesis?and?Mineralization, China Geological Survey, Wuhan 430205,Hubei, China |
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基金项目: | This work was supported by geological survey projects of the China Geological Survey (1212011120863,12120114039401, 12120114005901 and 12120115029401). |
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摘 要: | The Tongshankou Cu-Mo deposit, located in southeast Hubei province, is a typical skarn–porphyry type ore deposit closely related to the Tongshankou granodiorite porphyry, characterized by a high Sr/Y ratio.Detailed in situ analyses of the trace elements and U–Pb and Lu–Hf isotopes in zircons from the Tongshankou granodiorite porphyry were performed.Scarcely any inherited zircons were observed, and the analyzed zircons yielded highly concordant results with a weighted mean 206Pb/238 U age of 143.5 ± 0.45 Ma(n=20, mean square weighted deviation was 0.75), which was interpreted to represent the crystallization age of the Tongshankou granodiorite porphyry.The chondrite-normalized rare-earth element pattern was characterized by a slope that steeply rises from the light-group rare-earth elements(LREE) to the heavy-group rare-earth elements(HREE) with a positive Ce-anomaly and inconspicuous Eu-anomaly, which was coincident with the pattern of the zircons from the Chuquicamata West porphyry, Chile.The analyzed zircons also had relatively low 176Hf/177 Hf ratios of 0.282526–0.282604.Assuming t=143 Ma, the corresponding calculated initial Hf isotope compositions(εHf(t)) ranged from-5.6 to-2.9.The results of the in situ analysis of trace elements and U–Pb and Lu–Hf isotopes in zircons from the Tongshankou granodiorite porphyry suggest that a deep-seated process involving a thickened-crust/enriched-mantle interaction may play an important role in the generation of high Sr/Y-ratio magma and potentially in the generation of porphyry Cu-Mo systems.
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关 键 词: | trace element zircon Hf isotope granodiorite porphyry Middle-Lower Yangtze River metallogenic belt |
收稿时间: | 2014/3/26 0:00:00 |
修稿时间: | 2014/11/15 0:00:00 |
In Situ Analyses of Trace Elements,U–Pb and Lu–Hf Isotopes in Zircons from the Tongshankou Granodiorite Porphyry in Southeast Hubei Province,Middle‐Lower Yangtze River Metallogenic Belt,China |
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Authors: | XIA Jinlong HUANG Guicheng DING Lixue and CHENG Shunbo |
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Institution: | 1. Wuhan Center, China Geological Survey, Hubei, China;2. Research Center of Granitaic Diagenesis and Mineralization, China Geological Survey, Hubei, China |
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Abstract: | The Tongshankou Cu‐Mo deposit, located in southeast Hubei province, is a typical skarn–porphyry type ore deposit closely related to the Tongshankou granodiorite porphyry, characterized by a high Sr/Y ratio. Detailed in situ analyses of the trace elements and U–Pb and Lu–Hf isotopes in zircons from the Tongshankou granodiorite porphyry were performed. Scarcely any inherited zircons were observed, and the analyzed zircons yielded highly concordant results with a weighted mean 206Pb/238U age of 143.5 ± 0.45 Ma (n=20, mean square weighted deviation was 0.75), which was interpreted to represent the crystallization age of the Tongshankou granodiorite porphyry. The chondrite‐normalized rare‐earth element pattern was characterized by a slope that steeply rises from the light‐group rare‐earth elements (LREE) to the heavy‐group rare‐earth elements (HREE) with a positive Ce‐anomaly and inconspicuous Eu‐anomaly, which was coincident with the pattern of the zircons from the Chuquicamata West porphyry, Chile. The analyzed zircons also had relatively low 176Hf/177Hf ratios of 0.282526–0.282604. Assuming t=143 Ma, the corresponding calculated initial Hf isotope compositions (εHf(t)) ranged from ?5.6 to ?2.9. The results of the in situ analysis of trace elements and U–Pb and Lu–Hf isotopes in zircons from the Tongshankou granodiorite porphyry suggest that a deep‐seated process involving a thickened‐crust/enriched‐mantle interaction may play an important role in the generation of high Sr/Y‐ratio magma and potentially in the generation of porphyry Cu‐Mo systems. |
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Keywords: | trace element zircon Hf isotope granodiorite porphyry Middle-Lower Yangtze River metallogenic belt |
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