| Pressure-temperature Evolution of the Metapelites in the Motuo Area, the Eastern Himalayan Syntaxis |
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| 作者姓名： | DONG Hanwen XU Zhiqin LI Yuan and LIU Zhao |
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| 作者单位： | 1 State Key Laboratory of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China.
2 China University of Geosciences, Beijing 100083, China |
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| 基金项目： | This study was supported by the National Natural Science Foundation of China (40921001) and the Geological Survey of China (1212010818094). |
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| 摘 要： | The Motuo area is located in the east of the Eastern Himalayan Syntaxis. There outcrops a sequence of high-grade metamorphic rocks, such as metapelites. Petrology and mineralogy data suggest that these rocks have experienced three stages of metamorphism. The prograde metamorphic mineral assemblages(M1) are mineral inclusions(biotite + plagioclase + quartz ± sillimanite ± Fe-Ti oxides) preserved in garnet porphyroblasts, and the peak metamorphic assemblages(M2) are represented by garnet with the lowest XSps values and the lowest XFe# ratios and the matrix minerals(plagioclase + quartz ± Kfeldspar + biotite + muscovite + kyanite ± sillimanite), whereas the retrograde assemblages(M3) are composed of biotite + plagioclase + quartz symplectites rimming the garnet porphyroblasts. Thermobarometric computation shows that the metamorphic conditions are 562–714°C at 7.3–7.4 kbar for the M1 stage, 661–800°C at 9.4–11.6 kbar for the M2 stage, and 579–713°C at 5.5–6.6 kbar for the M3 stage. These rocks are deciphered to have undergone metamorphism characterized by clockwise P-T paths involving nearly isothermal decompression(ITD) segments, which is inferred to be related to the collision of the India and Eurasia plates.
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| 关 键 词： | 东喜马拉雅构造结 泥质岩 温度演化 墨脱 压力 矿物组合 变质岩 矿物包裹体 |
| 收稿时间： | 2013/10/30 0:00:00 |
| 修稿时间： | 2014/2/17 0:00:00 |
Pressure-temperature Evolution of the Metapelites in the Motuo Area,the Eastern Himalayan Syntaxis |
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| Authors: | DONG Hanwen XU Zhiqin LI Yuan LIU Zhao |
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| Institution: | [1]State Key Laboratory of Continental Tectonics andDynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China. [2]China University ofGeosciences, Beijing 100083, China |
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| Abstract: | The Motuo area is located in the east of the Eastern Himalayan Syntaxis. There outcrops a sequence of high‐grade metamorphic rocks, such as metapelites. Petrology and mineralogy data suggest that these rocks have experienced three stages of metamorphism. The prograde metamorphic mineral assemblages (M1) are mineral inclusions (biotite + plagioclase + quartz ± sillimanite ± Fe‐Ti oxides) preserved in garnet porphyroblasts, and the peak metamorphic assemblages (M2) are represented by garnet with the lowest XSps values and the lowest XFe# ratios and the matrix minerals (plagioclase + quartz ± K‐feldspar + biotite + muscovite + kyanite ± sillimanite), whereas the retrograde assemblages (M3) are composed of biotite + plagioclase + quartz symplectites rimming the garnet porphyroblasts. Thermobarometric computation shows that the metamorphic conditions are 562–714°C at 7.3–7.4 kbar for the M1 stage, 661–800°C at 9.4–11.6 kbar for the M2 stage, and 579–713°C at 5.5–6.6 kbar for the M3 stage. These rocks are deciphered to have undergone metamorphism characterized by clockwise P‐T paths involving nearly isothermal decompression (ITD) segments, which is inferred to be related to the collision of the India and Eurasia plates. |
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| Keywords: | metamorphic rocks P-T path Motuo area the Eastern Himalayan Syntaxis |
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