气候变化领域集成服务门户(CCPortal): P–T–t Path of Garnetites in South Altyn Tagh, West China: A Complete Record of the Ultradeep Subduction and Exhumation of Continental Crust

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DOI	10.1029/2019JB018881
	P–T–t Path of Garnetites in South Altyn Tagh, West China: A Complete Record of the Ultradeep Subduction and Exhumation of Continental Crust
	Dong J.; Wei C.; Chen J.; Zhang J.
发表日期	2020
ISSN	21699313
卷号	125 期号:2
英文摘要	We report here a detailed investigation of mineral chemistry, phase modelling and geochronology for garnetites from the Bashiwake ultrahigh pressure (UHP) terrane, South Altyn Tagh, West China. Three generations of mineral assemblages including two stages of melting were identified. The first generation is represented by the zoning with decreasing grossular and increasing pyrope and multiphase inclusions in garnet core. It records an early-stage prograde evolution from amphibolite facies to eclogite facies (1.7–2.5 GPa/710–850 °C) where the first stage of melting occurs. The second generation is characterized by the zoning in garnet mantle with increasing grossular and nearly constant pyrope, defining a later-stage prograde evolution to UHP peak with the minimum condition of 6.5–7.0 GPa/990 °C. The pressure is consistent with that constrained from the pigeonite exsolution particularly along (401) planes in clinopyroxene. The third generation includes the presence of perthite, plagioclase along with amphibole, suggesting the decompression from eclogite facies to HP–ultrahigh-temperature (UHT) granulite facies (~3.3–1.2 GPa/960–1020 °C) coupled with the second stage of melting. It is for the first time to get two metamorphic ages about 500 Ma and 486 Ma using in situ SIMS zircon dating which represent the prograde eclogite facies and decompressional granulite facies stages, suggesting the rocks staying at mantle depths for ~14 million years. The garnetites have recorded a complete metamorphic P–T–t history of continental ultradeep subduction to mantle depths of ~200 km or more followed by diapiring exhumation to the crust bottom. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	continental ultradeep subduction; garnet zoning; garnetite; P–T–t path; South Altyn Tagh
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187990
作者单位	MOE Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing, China; Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, China; Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China
推荐引用方式 GB/T 7714	Dong J.,Wei C.,Chen J.,等. P–T–t Path of Garnetites in South Altyn Tagh, West China: A Complete Record of the Ultradeep Subduction and Exhumation of Continental Crust[J],2020,125(2).
APA	Dong J.,Wei C.,Chen J.,&Zhang J..(2020).P–T–t Path of Garnetites in South Altyn Tagh, West China: A Complete Record of the Ultradeep Subduction and Exhumation of Continental Crust.Journal of Geophysical Research: Solid Earth,125(2).
MLA	Dong J.,et al."P–T–t Path of Garnetites in South Altyn Tagh, West China: A Complete Record of the Ultradeep Subduction and Exhumation of Continental Crust".Journal of Geophysical Research: Solid Earth 125.2(2020).