Tectonostratigraphic history of the southern Tian Shan, western China, from seismic reflection profiling

The modem Tian Shan formed due to the India-Eurasia collision. Uplift of the Tian Shan is recorded notably by the sedimentary sequences and subsidence history of the coupling foreland basins. We analyzed a 353-km-long seismic profile and logging data of four wells in the southern Tian Shan foreland area to decipher its tectonic, stratigraphic, and subsidence history. The sedimentary sequences comprise the Cambrian-Silurian, Devonian-Permian, Triassic, Jurassic-Cretaceous, and Paleogene tectonostratigraphic units, overlain by the late Oligocene-Quaternary foreland basin unit. The Jidike Formation is the oldest sedimentary sequence of the foreland succession, deposited at similar to 26 Ma based on magnetostratigraphic constraints, indicating that uplift of the southern Tian Shan was initiated by at least similar to 26 Ma. In addition, the tectonic subsidence rate of the southern Tian Shan foreland basin increased significantly since similar to 26 Ma due to lithospheric flexure caused by building of the topography of the southern Tian Shan. The envelope line of the forelandward onlaping points within the foreland unit indicates that the forebulge of the southern Tian Shan foreland basin migrated southwards at 1.6 +/- 0.1 mm/yr between similar to 26 Ma and similar to 12 Ma and at 14.6 +/- 0.1 mm/yr after similar to 12 Ma. The increase of migration rate at similar to 12 Ma suggests an accelerated convergence between the Tarim Basin and the Tian Shan.