Petrology,geochemistry and geochronology of Maoershan garnet amphibolite from central Qiangtang,Tibet

被引：0
|
作者：
Li C. [1 ,2 ,3 ]
Wang G. [4 ]
Zhao Z. [1 ,3 ]
Yang F. [2 ]
Li D. [5 ]
Wen J. [6 ]
Wang S. [7 ]
Li H. [1 ,3 ]
机构：
[1] Key Laboratory of Continental Tectonics and Dynamics, Ministry of Natural Resources, Institute of Geology, Chinese Academy of Geological Sciences, Beijing
[2] China National Institute of Standardization, Beijing
[3] Jiangsu Donghai Continental Deep Hole Crustal Activity National Observation and Research Station, Lianyungang
[4] School of Earth Sciences and Resources, China University of Geosciences, Beijing
[5] College of Earth Sciences, Chengdu University of Technology, Chengdu
[6] Administrative and Protection Bureau of China Precambrian Provincial Geological Nature Reserve, Kunming
[7] Exploration and Production Research Institute, Sinopec Northwest Oil Field Company, Urumqi
来源：
Yanshi Xuebao/Acta Petrologica Sinica | 2023年 / 39卷 / 12期
关键词：
Garnet amphibolite; Maoershan accretionary complex; P-T-t path; Paleo-Tethys Ocean; Qiangtang terrane in the central Tibetan Plateau;
D O I：
10.18654/1000-0569/2023.12.09
中图分类号：
学科分类号：
摘要：
Early Paleozoic metamorphic records were preserved in the Maoershan accretionary complex in the central Qiangtang in the hinterland of the Qinghai-Tibetan Plateau,which is of great significance for studying the Early Paleozoic tectonic evolution of the northern margin of the Gondwana. The Maoershan garnet amphibolite occurs as lenticular inside the amphibolite,and it is mainly composed of garnet,hornblende,diopside,plagioclase,muscovite,zoisite,chlorite,sphene and ilmenite. The whole-rock geochemical analysis of the garnet amphibolite shows that it has the characteristics of ophiolite in the subduction zone (SSZ type), which is consistent with the Cambrian-Ordovician ophiolite remnants in the region. According to petrography,mineral chemistry,phase equilibrium simulation and zircon dating results,the genesis and metamorphic process of the garnet amphibolite are revealed as follows: (1)The protolith of the garnet amphibolite was ophiolite remnant formed in the Tethys Ocean at ~ 477Ma;(2)The granulite facies metamorphism occurred in 394 ~ 383Ma,with the peak metamorphism P-T conditions of ~ 900℃ and ~ 1. 55GPa and the mineral assemblage of garnet + amphibole + diopside;(3)Early exhumation lead to the decrease of P-T to ~ 800℃ and ~ 1. 0GPa,with the mineral assemblage of garnet + amphibole + diopside + plagioclase;(4)The further amphibolite facies retrograde metamorphism occurred at 358 ~ 348Ma,with the mineral assemblage of amphibole + plagioclase + diopside + ilmenite,while the plagioclase + amphibole worm-like symplectite remains at the harbor of the coarse-grained garnet. Combined with regional ophiolite and magmatic records,the P-T-t evolution process of garnet amphibolite indicates the Early Paleozoic subduction of the Tethys Ocean,the Devonian back-arc expansion,and the Carboniferous accretion of the island arc. © 2023 Science Press. All rights reserved.
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页码：3661 / 3684
页数：23
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