Late Permian to Triassic intraplate orogeny of the southern Tianshan and adjacent regions, NW China

摘要

The South Tianshan Orogen and adjacent regions of Central Asia are located in the southwestern part of the Central Asian Orogenic Belt. The formation of South Tianshan Orogen was a diachronous, scissors-like process, which took place during the Palaeozoic, and its western segment was accepted as a site of the final collision between the Tarim Craton and the North Asian continent, which occurred in the late Palaeozoic. However, the post-collisional tectonic evolution of the South Tianshan Orogen and adjacent regions remains debatable. Based on previous studies and recent geochronogical data, we suggest that the final collision between the Tarim Craton and the North Asian continent occurred during the late Carboniferous. Therefore, the Permian was a period of intracontinental environment in the southern Tianshan and adjacent regions. We propose that an earlier, small-scale intraplate orogenic stage occurred in late Permian to Triassic time, which was the first intraplate process in the South Tianshan Orogen and adjacent regions. The later large-scale and well-known Neogene to Quaternary intraplate orogeny was induced by the collision between the India subcontinent and the Eurasian plate. The paper presents a new evolutionary model for the South Tianshan Orogen and adjacent regions, which includes seven stages: (I) late Ordovician–early Silurian opening of the South Tianshan Ocean; (II) middle Silurian–middle Devonian subduction of the South Tianshan Ocean beneath an active margin of the North Asian continent; (III) late Devonian–late Carboniferous closure of the South Tianshan Ocean and collision between the Kazakhstan-Yili and Tarim continental blocks; (IV) early Permian post-collisional magmatism and rifting; (V) late Permian–Triassic the first intraplate orogeny; (VI) Jurassic–Palaeogene tectonic stagnation and (VII) Neocene–Quaternary intraplate orogeny. Graphical abstract Display Omitted Highlights ? Seven evolutionary stages can be recognized in the southern Tianshan. ? The southern Tianshan has been an intracontinental setting since the Permian. ??Intraplate orogeny was active during the late Permian to the Triassic.