Home | Contact Us | Sitemap | 中文 | CAS | Director's Email
 
Location:Home > Papers > Recent Papers
Metamorphic records for subduction erosion and subsequent underplating processes revealed by garnet-staurolite-muscovite schists in central Qiangtang, Tibet TEXT SIZE: A A A
Subduction erosion is confirmed as a crucial geodynamic process of crustal recycling based on geological, geochemical, and geophysical observations at modern convergent plate margins. So far, not a single metamorphic record has been used for constraining a general tectonic evolution for subduction erosion. Here we first revealed metamorphic records for a subduction erosion process based on our study of the Late Paleozoic garnet-staurolite-muscovite schists in the central Qiangtang block, Tibet. Provenance analyses suggest that the protoliths of garnet-staurolite-muscovite schists have the Northern Qiangtang-affinity and were deposited in an active continental margin setting. Mineral inclusion data show that the early metamorphic stage (M-1) recorded blueschist facies pressure-temperature (P-T) conditions of 0.8-1.1 GPa and 402-441 degrees C, indicating that a part of the material from the overriding plate had been abraded into the subduction channel and undergone high-pressure/low-temperature metamorphism. The peak metamorphic stage (M-2) recorded amphibolite facies P-T conditions of 0.3-0.5 GPa and 470-520 degrees C. The Ar-40/Ar-39 cooling ages (263-259 Ma) yielded from muscovite suggest the amphibolite facies metamorphism (>263 Ma) occurred at oceanic subduction stage. The distinctly staged metamorphism defines a clockwise and warming decompression P-T-t path which reveals an underplating process following the early subduction erosion. During the tectonic process, the eroded low-density material escaped from the cold subduction channel and rise upward into the warm middle-lower crust of the upper plate, undergoing amphibolite facies metamorphism. Our new results revealed a complete evolutional process from the early subduction erosion to the subsequent underplating during the northward subduction of the Paleo-Tethys Ocean.
 

Publication name

 GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, 18 (1):266-279; 10.1002/2016GC006576 JAN 2017

Author(s)

 Zhang, Xiu-Zheng; Dong, Yong-Sheng; Wang, Qiang; Dan, Wei; Zhang, Chunfu; Xu, Wang; Huang, Ming-Liang

Corresponding author(s) 

 ZHANG Xiuzheng1; WANG Qiang1,2 
 zhangxz@gig.ac.cnwqiang@gig.ac.cn  
 1. Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou, Guangdong, Peoples R China
 2. CAS Ctr Excellence Tibetan Plateau Earth Sci, Beijing, Peoples R China 

Author(s) from IGCAS   HUANG Mingliang

View here for the details 

Copyright © Institute Of Geochemistry, Chinese Academy of Sciences All Rights Reserved.
Address: 99 West Lincheng Road, Guanshanhu District, Guiyang, Guizhou Province 550081, P.R.China
Tel: +86-851-85895239 Fax: +86-851-85895239 Email: web_en@mail.gyig.ac.cn