Late Cenozoic topographic growth of the South Tianshan Mountain Range: Insights from detrital apatite fission-track ages, northern Tarim Basin margin, NW China

The Cenozoic deformation of the Tianshan Mountain Range within the framework of the India-Eurasia collision has been extensively studied. Previous thermochronologic studies of bedrocks in this range suggest a complex Triassic-Early Cretaceous tectonic evolution and subsequent tectonic quiescence in the Late Cretaceous-Palaeogene. Thus, constraining the exhumation and topographic growth of the Tianshan Mountain Range during the Cenozoic remains a challenge. In this study we report new detrital apatite fission-track ages for a Cenozoic sedimentary succession on the northern margin of the Tarim Basin (Kuqa River section). Thermochronologic age trends along the analyzed succession reveal two major age-shifts in sediments deposited at ∼ 23 Ma and ∼ 10 Ma, which we ascribe to major drainage reorganizations in response to uplift of the South Tianshan Mountain Range, an interpretation corroborated by published detrital zircon U-Pb and heavy mineral data. By comparing detrital apatite fission-track data with existing bedrock data, we infer that both North Tianshan, Yili-Central Tianshan and South Tianshan provided detritus to the Tarim Basin during the early and middle Miocene. At ∼ 10 Ma, the South Tianshan Mountain Range experienced rapid uplift and started forming a topographic barrier that blocked sediments flowing from North Tianshan and Yili-Central Tianshan into the Tarim Basin. We suggest that progressive topographic growth of the South Tianshan Mountain Range favored the aridification of the Tarim region by acting as a barrier to westerly winds.