Tectonic evolution of the western Kunlun orogenic belt, western China

Abstract

The western Kunlun orogenic belt in western China evolved through the development of a large subduction–accretionary complex, including flysch sediments and granitic plutons, and by collision of three terranes, namely the North and South Kunlun and Karakorum–Qiangtang blocks from the early Paleozoic to the early Mesozoic. North-dipping subduction of the Paleo–Tethys ocean beneath the Kunlun terranes, which may have commenced in the Cambrian, produced an early Paleozoic Andean-type magmatic arc on the South Kunlun, and a marginal back arc basin, represented by the early Paleozoic Oytag–Kudi ophiolite belt, between the North and South Kunlun. A northward subduction zone consumed the basin and the young, hot upper plate lithosphere was obducted southward onto the South Kunlun following closure of the basin. This resulted in collision of the North and South Kunlun in the early Devonian. Continuous northward subduction of Paleo–Tethys resulted in the development of a Carboniferous–Triassic magmatic arc, and a back arc rifting sequence composed of the Carboniferous to Permian carbonates and clastic sediments on the North and South Kunlun terranes. The Paleo–Tethys ocean finally closed in the late Triassic–early Jurassic, when the Kunlun and Karakorum–Qiangtang blocks were accreted, with the Kara–Kunlun accretionary prism marking their suture zone.