Multistage exhumation and partial melting of high-T ultrahigh-pressure metamorphic rocks in continental subduction-collision zones

Abstract

High-temperature (HT; >850°C) metamorphism in continental collision orogens, particularly for those ultrahigh-pressure (UHP) metamorphic rocks, has become one of the remarkable topics in Earth science. It has bearing on the element and isotope behaviors of UHP rocks, their partial melting and related geodynamic effects during exhumation. In this paper, five representative continental collision orogens with typical HT/UHP rocks, including the Dabie orogen in China, the Kokchetav in Kazakhstan, the Caledonides in Greenland, the Rhodope in Greece, and the Erzgebirge in Germany are introduced, and their HT/UHP metamorphism and evolution processes are summarized. In addition, metamorphic P-T-t paths, multistage exhumation processes, and partial melting and preservation and retrogression of UHP index minerals during exhumation and their possible mechanisms are discussed. On this basis, the forthcoming key fields and scientific subjects of HT/UHP rocks within continental subduction channel are proposed.