Paleozoic tectono-thermal history of the amalgamation of the Tarim–North-China and Mongolian collages

In the Mongolian Collage, metamorphic pressure–temperature ( P – T ) and timing reveal a one-stage evolution defined by a duality of late Neoproterozoic–Ordovician subduction-related low T / P metamorphism and suprasubduction high T / P metamorphism recorded in the Mongolia–Manchuria and Baikal–Sayan belts. This was followed by gradual prevalence of suprasubduction high T / P metamorphism towards the late Paleozoic corresponding to the Altai and South Altai cycles. In the Tarim–North China Collage, metamorphic P – T and timing reveal a two-stage evolution, from dominant intermediate T / P metamorphism possibly resulting from Ordovician–Devonian amalgamation and Andean-type evolution of the collage, to dual low and high T / P metamorphism in the Carboniferous–Permian reflecting subduction–collision processes along the South Tianshan suture in the west and a suprasubduction evolution along the Solonker suture in the east. Altogether, the Paleozoic tectonometamorphic evolution of the two collages in the Central Asian Orogenic Belt shows remarkable differences, with the Mongolian Collage displaying features typical of peripheral accretionary style reflecting recurrent tectonic switches that can be regarded as a single orogenic system, and a two-stage evolution of the Tarim–North China Collage with features of both peripheral–accretionary and interior–collisional orogenic cycles, but mostly related to recurrent subductions of interior oceans.