| Re-Os Dating of the Pulang Porphyry Copper Deposit in Zhongdian,NW Yunnan, and Its Geological Significance |
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| 作者姓名： | ZENG Pusheng HOU Zengqian WANG Haiping QU Wenjun MENG Yifeng YANG Zhusen and LI Wenchang Institute of Mineral Resources Chinese Academy of Geological Sciences Beijing National Research Center of Geoanalysis Chinese Academy of Geological Sciences Beijing Yunnan Institute of Geological Survey Kunming Yunnan |
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| 作者单位： | ZENG Pusheng，HOU Zengqian，WANG Haiping，QU Wenjun，MENG Yifeng，YANG Zhusen and LI Wenchang Institute of Mineral Resources，Chinese Academy of Geological Sciences，Beijing 100037;National Research Center of Geoanalysis，Chinese Academy of Geological Sciences，Beijing 100037 Yunnan Institute of Geological Survey，Kunming，Yunnan 651000 |
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| 摘 要： | The Pulang porphyry copper deposit is located in the Zhongdian island arc belt, NW Yunnan, in the central part of the Sanjiang area, SW China, belonging to the southern segment of the Yidun island arc belt on the western margin of the Yangtze Platform. In the Yidun island arc, there occur well-known "Gacun-style" massive sulfide deposits in the northern segment and plenty of porphyry copper deposits in the southern segment, of which the Pulang porphyry copper deposit is one of the representatives. Like the Yulong porphyry copper deposit, this porphyry copper deposit is also one of the most important porphyry copper deposits in the eastern Qinghai-Tibet Plateau. But it is different from other porphyry copper deposits in the eastern Qinghai-Tibet Plateau (e.g. those in the Gangdise porphyry copper belt and Yulong porphyry copper belt) in that it formed in the Indosinian period, while others in the Himalayan period. Because of its particularity among the porphyry copper deposits of China, this porphyry copp
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| 关 键 词： | 铼-锇测定法 铜斑岩 云南 沉积矿 |
Re-Os Dating of the Pulang Porphyry Copper Deposit in Zhongdian,NW Yunnan, and Its Geological Significance |
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| Authors: | ZENG Pusheng HOU Zengqian WANG Haiping QU Wenjun MENG Yifeng YANG Zhusen and LI Wenchang Institute of Mineral Resources Chinese Academy of Geological Sciences Beijing National Research Center of Geoanalysis Chinese Academy of Geological Sciences Beijing Yunnan Institute of Geological Survey Kunming Yunnan |
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| Abstract: | Abstract The Pulang porphyry copper deposit is located in the Zhongdian island are belt, NW Yunnan, in the central part of the Sanjiang area, SW China, belonging to the southern segment of the Yidun island arc belt on the western margin of the Yangtze Platform. In the Yidun island arc, there occur well‐known “Gacun‐style” massive sulfide deposits in the northern segment and plenty of porphyry copper deposits in the southern segment, of which the Pulang porphyry copper deposit is one of the representatives. Like the Yulong porphyry copper deposit, this porphyry copper deposit is also one of the most important porphyry copper deposits in the eastern Qinghai‐Tibet Plateau. But it is different from other porphyry copper deposits in the eastern Qinghai‐Tibet Plateau (e.g. those in the Gangdise porphyry copper belt and Yulong porphyry copper belt) in that it formed in the Indosinian period, while others in the Himalayan period. Because of its particularity among the porphyry copper deposits of China, this porphyry copper deposit is of great significance for the study of the basic geology and the evaluation and prediction of mineral resources in the Zhongdian island arc belt. However, no accurate chronological data are available for determining the timing of mineralization of the porphyry copper deposit. By field observation in the study area and Re‐Os dating of molybdenite and K‐Ar dating of hydrothermal minerals and whole rock from the typical geological bodies, the timing of mineralization of the porphyry copper deposit has systematically been determined for the first time. The K‐Ar age for the hydrothermal mineralization of biotite‐quartz monzonitic porphyry that has undergone patassic silicate (biotite and K‐feldspar) alteration ranges from 235.4±2.4 to 221.5±2.0 Ma and the Re‐Os age for molybdenite in the quartz‐molybdenite stage is ～213±3.8 Ma. These data are very close to each other, suggesting that the ore‐forming processes of the Pulang porphyry copper deposit was completed in the Indosinian. But the K‐feldspar K‐Ar age of the main orebodies suggests that the hydrothermal activity related to porphyry copper mineralization continued till ～182.5±1.8 Ma. This indicates that the lifespan of the hydrotthermal system related to porphyry copper mineralization may have lasted at least 40 Ma. This hydrothermal thermal system with such a long lifespan may be one of the necessary conditions for forming large porphyry copper deposits with a high grade. No late Yanshanian and/or Himalayan magmatism (mineralization) were superimposed in the Pulang porphyry copper deposit. |
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| Keywords: | Re-Os dating porphyry copper Pulang Zhongdian Yunnan China |
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