Preservation of Re‐Os isotope signatures in pyrite throughout low‐T,high‐P eclogite facies metamorphism |
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| Authors: | David van Acken Wen Su Jun Gao Robert A Creaser |
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| Institution: | 1. Department of Earth and Atmospheric Sciences, University of Alberta, , Edmonton, AB, T6G2E3 Canada;2. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, , Beijing, 100029 China |
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| Abstract: | Pyrite in LT–HP eclogites from the western Tianshan orogenic belt yields a Re‐Os age of 378.1 ± 8.9 Ma, which is 30–70 Ma older than ages previously obtained for the same rocks using the Rb–Sr, Sm–Nd, Ar–Ar, U–Pb, and Lu–Hf isotope systems. The Tianshan LT–HP eclogite experienced temperatures of up to ~570 °C combined with pressures of up to 2.1 GPa during metamorphism. These conditions are below the transition of pyrite to pyrrhotite, which defines both pyrite stability and possibly its closure temperature for Re‐Os. Pyrite can preserve Re‐Os signatures through eclogite facies peak metamorphic conditions, and thus allow determination of the formation age of pyrite in the protolith. |
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