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High-pressure granulite from Western Kunlun,northwestern China: Its metamorphic evolution,zircon SHRIMP U-Pb ages and tectonic implication |
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| Authors: | Qu?JunFeng |
| Institution: | 1. MOE Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Science, Peking University, Beijing 100871, China 2. Henan Polytechnic University, Jiaozuo 454100, China 3. Geological Survey of Henan Province, Zhengzhou 450007, China |
| Abstract: | High-pressure mafic granulites occurring as lenticular bodies within garnet-amphibolites in Kangxiwar Fault have been first reported in this paper. The P-T conditions of two metamorphic stages were obtained using calibrated geothermal barometers and ThermoCalc Program. The peak metamorphic condition of these high-pressure granulites is about 760–820°C, 1.0–1.2 GPa and the retrograde metamorphic condition is about 620–720°C, 0.7–0.8 GPa. The petrological studies show that they have a near-isobaric cooling P-T path which suggests that the Western Kunlun underwent initial crustal thickening, subsequent exhumation and cooling. The SHRIMP zircon U-Pb dating gives two groups of ages for high-pressure granulites. One is 177±6 Ma which is obtained from the rim of the zircon. We consider this age should be the metamorphic age. And the other is 456±30 Ma which is obtained from the core of the zircon and should be the protolith age. The formation of these high-pressure granulites in western Kunlun is closely correlated with the evolution of the Paleo-Tethys and has important implications for the research on Tethys and Paleo-Asian tectonic zone. Supported by Geological Survey of Henan Province and the National Natural Science Foundation of China (Grant No. 40325005) |
| Keywords: | Western Kunlun Kangxiwar Fault high-pressure granulite P-T path SHRIMP U-Pb dating of zircon |
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