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Article

Ultra-High Pressure Metamorphism and Geochronology of Garnet Clinopyroxenite in the Paleozoic Dunhuang Orogenic Belt, Northwestern China

1
College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, P.O. Box 4588, Beijing 100049, China
2
State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, China
*
Author to whom correspondence should be addressed.
Minerals 2021, 11(2), 117; https://doi.org/10.3390/min11020117
Received: 27 December 2020 / Revised: 21 January 2021 / Accepted: 21 January 2021 / Published: 24 January 2021
(This article belongs to the Section Mineral Geochemistry and Geochronology)
Ultra-high pressure (UHP) metamorphism is recorded by garnet clinopyroxenite enclaves enclosed in an undeformed, unmetamorphosed granitic pluton, northeastern Paleozoic Dunhuang orogenic belt, northwestern China. The protoliths of the garnet clinopyroxenite might be basic or ultrabasic volcanic rocks. Three to four stages of metamorphic mineral assemblages have been found in the garnet clinopyroxenite, and clockwise metamorphic pressure–temperature (P-T) paths were retrieved, indicative of metamorphism in a subduction environment. Peak metamorphic P-T conditions (790–920 °C/28–41 kbar) of garnet clinopyroxenite suggest they experienced UHP metamorphism in the coesite- or diamond-stability field. The UHP metamorphic event is also confirmed by the occurrence of high-Al titanite enclosed in the garnet, along with at least three groups of aligned rutile lamellae exsolved from the garnet. Secondary ion mass spectrometry (SIMS) U-Pb dating of metamorphic titanite indicates that the post-peak, subsequent tectonic exhumation of the UHP rocks occurred in the Devonian period (~389–370 Ma). These data suggest that part of the Paleozoic Dunhuang orogenic belt experienced UHP metamorphism, and diverse metamorphic facies series prevailed in this Paleozoic orogen. It can be further inferred that most of the UHP rocks in this orogen remain buried. View Full-Text
Keywords: Dunhuang Orogenic Belt; garnet clinopyroxenite; geochronology; high-Al titanite; rutile lamellae; P-T path; ultra-high pressure metamorphism Dunhuang Orogenic Belt; garnet clinopyroxenite; geochronology; high-Al titanite; rutile lamellae; P-T path; ultra-high pressure metamorphism
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MDPI and ACS Style

Li, Z.; Wang, H.; Zhang, Q.; Shi, M.-Y.; Lu, J.-S.; Liu, J.-H.; Wu, C.-M. Ultra-High Pressure Metamorphism and Geochronology of Garnet Clinopyroxenite in the Paleozoic Dunhuang Orogenic Belt, Northwestern China. Minerals 2021, 11, 117. https://doi.org/10.3390/min11020117

AMA Style

Li Z, Wang H, Zhang Q, Shi M-Y, Lu J-S, Liu J-H, Wu C-M. Ultra-High Pressure Metamorphism and Geochronology of Garnet Clinopyroxenite in the Paleozoic Dunhuang Orogenic Belt, Northwestern China. Minerals. 2021; 11(2):117. https://doi.org/10.3390/min11020117

Chicago/Turabian Style

Li, Zhen, Hao Wang, Qian Zhang, Meng-Yan Shi, Jun-Sheng Lu, Jia-Hui Liu, and Chun-Ming Wu. 2021. "Ultra-High Pressure Metamorphism and Geochronology of Garnet Clinopyroxenite in the Paleozoic Dunhuang Orogenic Belt, Northwestern China" Minerals 11, no. 2: 117. https://doi.org/10.3390/min11020117

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