Metamorphism of Qinling Complex in Northern West Qinling Orogen: Petrology, Phase Equilibria Modelling of Paragneiss and Their Geological Implication
Mao Xiaohong
Zhang Jianxin
Yu Shengyao
Li Yunshuai
Yu Xingxing
Lu Zenglong
Zhou Guisheng
Abstract：Studies of high-grade metamorphic rocks in an ancient orogenic belt can provide important constraints on the formation and tectonic evolution of orogen.The Qinling complex in the northern West Qinling orogen mainly consists of orogneiss,paragneiss,minor metabasite (mafie granulite) and marble.The petrography,mineral chemistry and phase equilibria modelling in this study show that paragneiss has experencied three metamorphic evolution stages.Stage 1 is the prograde stage,characterized by biotite and quartz occurring as inclusions in garnet.Stage 2 is the peak metamorphic stage,and mineral assemblage in this stage is interpreted to be garnet+ sillimanite+ K-feldspar+ plagioclase+ biotite+ quartz+ rutile,which formed in P-T conditions of 793-803 ℃ and 8.8-9.5 kbar.Stage 3 is the retrograde stage with decrease in temperature and pressure,which is recorded by garnet and plagioclase.Combining with previous data,it is suggested that the Qinling complex in the northern West Qinling orogen has experienced Early Paleozoic metamorphism and anataxis related to collision orogenesis.
Keywords：West QinlingQinling complexparagneissmetamorphismphase equilibria modellingpetrology
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：18( 278-295 )