Low-Pressure Metamorphism of Granulite Facies in an Early Proterozoic Orogenic Event in Central Inner Mongolia

作     者：Liu Xishan, Jin Wei and Li Shuxun Changchun University of Earth Sciences, Changchun, Jilin Sun Sheping 

作者机构：Changchun University of Earth Sciences Changchun Jilin 

出 版 物：《Acta Geologica Sinica(English Edition)》 (地质学报（英文版）)

年 卷 期：1993年第67卷第1期

页      面：63-77页

核心收录：

学科分类：0709[理学-地质学] 081803[工学-地质工程] 07[理学] 08[工学] 0818[工学-地质资源与地质工程] 

基　　金：This research was supported by the National Natural Science Foundation of China 

主　　题：Early Proterozoic change of mineral assemblages thrusting extension orogenic event. 

摘      要：According to the kinds of feldspar and rock associations in the Ai-rich gneisses, the low-pressure metamorphic crust of the Early Proterozoic granulite facies in central Inner Mongolia can be divided into southern and northern belts which are composed of six rock associations. They represent the relevant rock sequences of the layered metamorphic rock series formed under specific metamorphic temperature and pressure conditions as well as tectonic environments. Mineral inclusions and reaction texture have recorded that the medium-temperature high-pressure mineral assemblages are replaced by the high-temperature low-pressure mineral assemblages, thus, giving rise to: garnet+quartz→ hypersthene+plagioclase; kyanite→sillimanite and garnet+kyanite/sillimanite+quartz→cordierite. The deformation fabrics of the rocks, the change of mineral assemblages and the PTt path of metamorphism indicate that the contempranceous high-temperature normal-slip ductile shearing is the main cause of the formation of the low-pressure metamorphic crust of granulite facies. In the orogenic event, the co-action of thrusting and extension resulted in the change of a medium-temperature high-pressure metamorphic environment into the high-temperature low-pressure metamorphic conditions.