| Integrated P-T Paths of the High-Pressure Rocks and Their Tectonic Implications for the Mountain-Building of the North Qilian, China |
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| 作者单位： | CHEN Wei-Min，HUANG Young-Ching，Yoshiyuki IIZUKA，LO Ching-Hua，WUHanquan，SONG Shuguang，YANG Jingsui，XU Zhiqin and YANG Houng-Yi Department of Earth Sciences，National Central University，Chungli，Taiwan，China Institute of Earth Sciences，Academia Sinica，Taipei，Taiwan，China Department of Geology Science，National Taiwan University，Taipei，Taiwan，ChinaXi'an Institute of Geology and Mineral Resources，Xi'an 710054，China. Institute of Geology，Chinese Academy of Geological Sciences，Beijing 100037，China Department of Earth Sciences，National Cheng Kung University，Tainan，Taiwan，China |
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| 摘 要： | After the integration of petrographic study, geothermobarometry and Gibbs method, the synthetic P-T paths for the rocks from different geological profiles in the North Qilian, China, have been derived. The composite P-T paths from different methods indicate that all the high-pressure rocks in the Qilian area recorded P-T paths with clockwise loops starting at the blueschist facies, later reaching peak metamorphism at the blueschist facies, eclogite fades or epidote-amphibolite facies and ending up with the greenschist facies. The incremental Ar-Ar dating shows that the plateau ages for the high-pressure rocks range from 410 to 443 Ma. The plateau ages could be used as a minimum age constraint for the subduction that resulted in the formation of these high-pressure rocks in the Qilian area. It is proposed that the late-stage decompressional and cooling P-T paths with ends at the greenschist facies for these high-pressure rocks probably reflect the uplift process which could occur after shifting the arc-t
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Integrated P-T Paths of the High-Pressure Rocks and Their Tectonic Implications for the Mountain-Building of the North Qilian, China |
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| Authors: | CHEN Wei‐Min HUANG Young‐Ching Yoshiyuki IIZUKA LO Ching‐Hua WU Hanquan SONG Shuguang YANG Jingsui XU Zhiqin YANG Houng‐Yi |
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| Abstract: | After the integration of petrographic study, geothermobarometry and Gibbs method, the synthetic P-T paths for the rocks from different geological profiles in the North Qilian, China, have been derived. The composite P-T paths from different methods indicate that all the high-pressure rocks in the Qilian area recorded P-T paths with clockwise loops starting at the blueschist facies, later reaching peak metamorphism at the blueschist facies, eclogite fades or epidote-amphibolite facies and ending up with the greenschist facies. The incremental Ar-Ar dating shows that the plateau ages for the high-pressure rocks range from 410 to 443 Ma. The plateau ages could be used as a minimum age constraint for the subduction that resulted in the formation of these high-pressure rocks in the Qilian area. It is proposed that the late-stage decompressional and cooling P-T paths with ends at the greenschist facies for these high-pressure rocks probably reflect the uplift process which could occur after shifting the arc-trench tectonic system to the system of continental orogenic belts. The retrograde paths for the high-pressure rocks in the North Qilian tectonic belt are characterized by dramatic decompression with slight cooling, which suggests very rapid exhumation. Petrography supports that the mountain-building for the Qilian mountain range could undergo a very fast process which caused rapid uplift and denudation. |
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| Keywords: | petrology integrated P-T path high-pressure rocks mountain-building of North Qilian China |
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