Metamorphic P-T Path of High-Pressure Mafic Granulite (Retrograded Eclogite) from Dinggye of Tibet and Its Tectonic Implication
Ding Zigeng
Tong Laixi
Liu Xiaohan
Liu Zhao
Zhou Xuejun
Abstract：Dinggye is located in the central part of the Greater Himalayan crystalline complex (GHC) in southern Tibet.It is essential to investigate the metamorphic P-T path of granulite in this area to better understand the collision and uplifting process of the Tibetan plateau.The petrological study of the high-pressure mafic granulite (retrograded eelogite) from the region indicates four stages:(1) peak eclogite facies mineral assemblage (M1) consists of garnet (core)+omphacite (psedomorph)+ quartz + rutile;(2) high-pressure granulite facies mineral assemblage (M2) comprises garnet (mantle) +clinopyroxene+ plagioclase+ilmenite + amphibole + biotite;(3) medium-pressure granulite facies assemblage (M3) is composed of garnet (rim) + orthopyroxene + plagioclase + biotite;(4) amphibolite facies mineral assemblage (M4) consists of amphibole+plagioclase.Using the THERMOCALC program,the thermodynamic modeling in the NCFMASHTO system has been undertaken for the high-pressure mafic granulite.Combined with the conventional thermobarometers and the average P-T estimates,the P-T conditions of the different metamorphic stages are estimated to be 786-826 ℃,0.78-0.96 GPa (M2);798-850 ℃,0.71-0.75 GPa (M3);and 610-666 ℃,0.51-0.60 GPa (M4),respectively,indicating a post-peak clockwise P-T path characterized by nearly isothermal decompression.Combined with geological data available,we propose that the highpressure mafic granulite (retrograded eclogite) of the Dinggye formed during the Himalayan collisional orogeny,and underwent a post-peak tectonic uplift process of nearly isothermal decompression.
Keywords：high-pressure mafic granuliteP-T pathcollisional orogenesisGreater HimalayaDinggyepetrology
Publication Date：2018-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：16( 220-235 )