Petrogenesis and thermal history of the Yulong porphyry copper deposit, Eastern Tibet: insights from U-Pb and U-Th/He dating, and zircon Hf isotope and trace element analysis

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• 作者：Jinxiang Li (1) ljx@mail.iggcas.ac.cn
  Kezhang Qin (2) kzq@mail.iggcas.ac.cn
  Guangming Li (2) liguangming0505@yahoo.com.cn
  Mingjian Cao (2) jiancaoming@163.com
  Bo Xiao (23) xiaobo06@mail.iggcas.ac.cn
  Lei Chen (4) chenlei@mail.igcas.ac.cn
  Junxing Zhao (2) junxingzhao@tom.com
  Noreen J. Evans (56) Noreen.Evans@csiro.au
  Brent I. A. McInnes (56) B.McInnes@curtin.edu.au
• 刊名：Mineralogy and Petrology
• 出版年：2012
• 出版时间：July 2012
• 年：2012
• 卷：105
• 期：3-4
• 页码：201-221
• 全文大小：6.0 MB
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• 作者单位：1. Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, 4A Datun Road, Chaoyang District, Beijing, 100085 China2. Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beitucheng West Road 19#, Chaoyang District, Beijing, 100029 People’s Republic of China3. China Nonferrous Metal Mining (Group) Co., Ltd, Anli Road 10#, Chaoyang District, Beijing, 100029 China4. MRL Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Road, Beijing, 100037 China5. CSIRO Earth Science and Resource Engineering, 26 Dick Perry Ave., Kensington, WA 6151, Australia6. John De Laeter Center for Isotope Research, Department of Applied Geology/Applied Physics, Curtin University, Perth, WA 6945, Australia
• ISSN：1438-1168

文摘

The Yulong porphyry copper deposit (6.5 Mt at 0.46 % Cu) in eastern Tibet was formed in a post-collisional setting. New zircon U–Pb and U–Th/He ages, apatite U–Th/He ages and in-situ zircon Hf isotopic and trace element data for the Yulong ore-bearing adakitic porphyries elucidate the thermal history and petrogenesis of the deposit. Zircon U–Pb ages range from from 41.2 Ma to 40.7 Ma, indicating an Eocene formation age. Combined with the zircon U–Th/He age of 37.5?±?1.2 Ma, results suggest that magmatic-hydrothermal evolution lasted up to 5 m.y. The apatite U–Th/He age of 33.4?±?0.9 Ma reflects Yulong deposit exhumation during the ~33–30 Ma Tibetan uplift. Moreover, the high εHf(t)-values (7.1?~?12.2) zircon yield the highest ΣREE content, higher Y/Hf, lower Ce/Ce* and higher Th/U ratios compared to inherited zircon or magmatic zircon suggesting that the high εHf(t) zircon crystallized from another magma, and that magma mixing probably contributed to the adakitic porphyries at Yulong. In addition, inherited and magmatic zircon with the lowest εHf(t) values (?20.6?~??4.4) suggest crustal contamination. The positive zircon εHf(t) values indicate a source in the juvenile arc lower crust. Significantly, the juvenile arc lower crust inherited arc magma characteristics (abundant F, Cl, Cu and high oxidation state), which are now found in the porphyry Cu–Mo deposits.