| Emplacement Ages and Petrogenesis of the Molybdenum–bearing Granites in the Jinduicheng Area of East Qinling, China: Constraints from Zircon U–Pb Ages and Hf Isotopes |
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| 作者姓名： | LI Hongying WANG Xiaoxi YE Huishou and YANG Lei |
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| 作者单位： | 1 Key Laboratory of Metallogeny and Mineral Resource Assessment, Ministry of Land and Resources; Institute of Mineral Resources, CAGS, Beijing 100037, China
2 Research Institute, China National offshore Oil Corp. (CNOOC), Beijing 100027 |
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| 基金项目： | This study was supported by the Basic Research Project for the Central Public Welfare Scientific Institutions (K1019) granted by the Institute of Mineral Resources, Chinese Academy of Geological Sciences, the ministry of land and resources public welfare industry research project of China (200911007-6), and the national crisis's mine resources prospecting project of China (20089949). We wish to acknowledge the cooperation received from the Jinduicheng Molybdenum Group company, Ltd., and the leadership of the Shaanxi No.13 Geological Brigade. We thank Dr Hou Kejun and Dr Guo Chunli for technical support during U–Pb zircon dating and Lu–Hf isotopic analytical work. |
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| 摘 要： | The Mesozoic porphyry assemblage in the Jinduicheng area is a special molybdenum area in China, the Mo deposits, including the Jinduicheng, Balipo, Shijiawan, Huanglongpu, are distributed. The emplacement age and geochemical features of the granites in the Jinduicheng area can provide essential information for the exploration and development of the porphyry molybdenum deposit. In this study, we report LA–ICP–MS zircon U–Pb age and zircon Hf isotopic compositions of granite porphyries from the Jinduicheng area, and provide insights on the petrogensis and source characteristics of the granites. The results show that the zircon U–Pb ages of the Jinduicheng granite porphyry (143±1 Ma) and the Balipo granite (154±1 Ma), agree well with the Re–Os ages of molybdenite in the Jinduicheng molybdenum polymetallic deposit (139±3 Ma) and the Balipo molybdenum polymetallic deposit (156±2 Ma), indicating that the emplacement of granite porphyries occurred between Late Jurassic and Early Cretaceous. Zircons granite from the Jinduicheng area give the εHf(t) values mainly ranging from ?10 to ?16, and ?20 to ?24, respectively, corresponding to two–stage model ages (tDM2: mainly focused on 1.86–2.0 Ga, and 2.2–2.6 Ga, respectively) of zircons of the granite from the Jinduicheng values. The ore–forming materials are mainly derived from crust, with minor mantle substances. Zircons of the granite from the Balipo area give εHf(t) values ranging from ?18 to ?20, ?28 to ?38, and ?42 to ?44, respectively, corresponding to two–stage model ages (tDM2: mainly focused on 1.88–3.0 Ga, and 3.2–3.90 Ga, respectively). the εHf(t) values of the Jinduicheng porphyry more than that of the Balipo porphyry, and two–stage model ages (tDM2) less than that of the Balipo porphyry, shows that he source of the porphyries originated from ancient lower crustal materials in the Jinduicheng area, and mixed younger components, more younger components contributed for the source of the Jinduicheng porphyry.
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| 关 键 词： | granites petrogensis LA–ICP–MS U–Pb dating Zircon Hf isotope Jinduicheng |
| 收稿时间： | 2012/3/27 0:00:00 |
| 修稿时间： | 2012/4/27 0:00:00 |
Emplacement Ages and Petrogenesis of the Molybdenum–bearing Granites in the Jinduicheng Area of East Qinling,China: Constraints from Zircon U–Pb Ages and Hf Isotopes |
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| Authors: | LI Hongying WANG Xiaoxia YE Huishou YANG Lei |
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| Institution: | 1. Key Laboratory of Metallogeny and Mineral Resource Assessment, Ministry of Land and Resources;2. Institute of Mineral Resources, CAGS, Beijing 100037, China;3. Research Institute, China National offshore Oil Corp. (CNOOC), Beijing 100027 |
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| Abstract: | The Mesozoic porphyry assemblage in the Jinduicheng area is a special molybdenum area in China, the Mo deposits, including the Jinduicheng, Balipo, Shijiawan, Huanglongpu, are distributed. The emplacement age and geochemical features of the granites in the Jinduicheng area can provide essential information for the exploration and development of the porphyry molybdenum deposit. In this study, we report LA–ICP–MS zircon U–Pb age and zircon Hf isotopic compositions of granite porphyries from the Jinduicheng area, and provide insights on the petrogensis and source characteristics of the granites. The results show that the zircon U–Pb ages of the Jinduicheng granite porphyry (143±1 Ma) and the Balipo granite (154±1 Ma), agree well with the Re–Os ages of molybdenite in the Jinduicheng molybdenum polymetallic deposit (139±3 Ma) and the Balipo molybdenum polymetallic deposit (156±2 Ma), indicating that the emplacement of granite porphyries occurred between Late Jurassic and Early Cretaceous. Zircons granite from the Jinduicheng area give the εHf(t) values mainly ranging from –10 to –16, and –20 to –24, respectively, corresponding to two–stage model ages (tDM2: mainly focused on 1.86–2.0 Ga, and 2.2–2.6 Ga, respectively) of zircons of the granite from the Jinduicheng values. The ore–forming materials are mainly derived from crust, with minor mantle substances. Zircons of the granite from the Balipo area give εHf(t) values ranging from –18 to –20, –28 to –38, and –42 to –44, respectively, corresponding to two–stage model ages (tDM2: mainly focused on 1.88–3.0 Ga, and 3.2–3.90 Ga, respectively), the εHf(t) values of the Jinduicheng porphyry more than that of the Balipo porphyry, and two–stage model ages (tDM2) less than that of the Balipo porphyry, shows that he source of the porphyries originated from ancient lower crustal materials in the Jinduicheng area, and mixed younger components, more younger components contributed for the source of the Jinduicheng porphyry. |
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| Keywords: | granites petrogensis LA–ICP–MS U–Pb dating Zircon Hf isotope Jinduicheng |
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