Tectonic evolution of the West Kunlun: Geochronologic and geochemical constraints from Kudi granitoids

Abstract

The West Kunlun contains important information about the early evolutionary history of the Tibetan Plateau. Single-grain zircon U-Pb dating and systematic geochemical analyses were conducted on representative granitic plutons from the Kudi area. The earliest Paleozoic magmatism (471 ± 5 Ma) possesses characteristics of volcanic-arc granites, indicating that Proto-Tethys started to close in the Mid-Ordovician. An arc-continent collision occurred in the Late Ordovician, corresponding to the closure of Proto-Tethys. Following the collision, extensional deformation began in the Early Devonian and gave rise to a post-dynamic, A-type North Kudi Pluton (405 ± 2 Ma) and coeval lamprophyre dikes. Extension was pervasive throughout the whole Kunlun orogenic belt, and was responsible for Devonian to Early Permian magmatic quiescence. The reoccurrence of magmatism in the West Kunlun took place in the Early Permian, when Paleo-Tethys started to be consumed, and a new subduction zone developed in the West Kunlun. Paleo-Tethys closed by the Late Triassic (214 ± 1 Ma), and led to rapid uplift and voluminous post-collisional granites.