Cooling and exhumation of the mid-Jurassic porphyry copper systems in Dexing City,SE China: insights from geo- and thermochronology |
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Authors: | Xuan Liu Hong-rui Fan Noreen J. Evans Geoffrey E. Batt Brent I. A. McInnes Kui-feng Yang Ke-zhang Qin |
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Affiliation: | 1. Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China 2. John de Laeter Centre for Isotope Research, Department of Applied Geology, Curtin University, Perth, 6845, Australia 3. Center for Exploration Targeting, School of Earth and Environment, University of Western Australia, Crawley, 6009, Australia
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Abstract: | The Dexing porphyry copper and Yinshan polymetallic deposits in Dexing City, southeastern China are both giant porphyry ore systems. Located 15 km apart, they formed synchronously and share a similar magma source and metallogenic evolution, but their metal endowment, dominant rock types, and alteration assemblages differ significantly. In this contribution, we investigate the cause of these distinctions through new molybdenite Re–Os ages and zircon and apatite (U–Th)/He thermochronology data. Dexing has a molybdenite Re–Os age of ~170.3 Ma, zircon (U–Th)/He (ZHe) ages of 110 to 120 Ma and apatite (U–Th)/He (AHe) ages of 7 to 9 Ma. In contrast, Yinshan has older ZHe ages of 128 to 140 Ma and an AHe age of ~30 Ma. Viewed in combination with previously published data, we conclude that the apparently slow cooling experienced by these bodies is primarily a reflection of their experiencing multiple episodes of thermal disturbance. We tentatively infer that both deposits were exposed in the Late Miocene or more recent time, with the Dexing deposit more deeply exhumed than Yinshan. Our study has exploration implications for deeper porphyry-style ores at Yinshan and for porphyry deposits in non-arc (intraplate) settings in general. |
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