Abstract

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Author(s):: JIANG Wei-jia; LIU Yi-can; 1. Key Laboratory of Crust-mantle Materials and Environments, Chinese Academy of Sciences, Hefei 230026,Anhui, China; 2. School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, Anhui, China

Keywords:: UHP metamorphic belt; metamorphic heterogeneity; continental deep subduction; exhumation; collisional orogenic belt; eclogite; retrogression

Abstract:: Ultrahigh-pressure (UHP) index minerals, such as coesite and diamond in eclogites and related metamorphosed supracrustal rocks from various orogenic belts, suggest that continental crustal rocks can be subducted to mantle depths of more than 120 km and subsequently return to the surface. Furthermore, eclogites and related eclogite-facies rocks, and low-grade mineral assemblage-bearing rocks (i.e. metagranite, granitic gneiss, meta-basalt and amphibolite) commonly coexist in UHP metamorphic belts. However, their relationship and petrogenetic links between high-grade and lower grade assemblage-bearing rocks are often matter of debate. Hence, to clarify the metamorphic evolutionary histories and the correlation of the two groups of rocks plays a significant role in understanding the continental deep subduciton and exhumation processes. Some investigations on the metamorphic heterogeneity within a single UHP metamorphic belt were summarized. On this basis, several key factors such as protolith nature, metamorphic fluids, structural deformation and retrogression, which affect the preservation of UHP metamorphic records, were discussed.