Cenozoic Pulsed Rise and Growth of the Chinese South Tianshan Revealed by Zircon and Apatite Provenance Analyses: Implications for Stepwise Aridification in the Tarim Basin

Cenozoic uplift in the Tianshan played an important role in driving Proto-Paratethys Sea retreat and Asian aridification. However, most paleoclimate studies have focused on the Pamir-Tianshan corridor, and frequently overlook the role of the entire Tianshan range in modifying the Central Asian climate during Cenozoic uplift. When and how Cenozoic deformation of Tianshan was initiated and propagated are intensively debated which makes its role in contributing to climate change in Central Asia more ambiguous. To address this issue, this study presents new detrital zircon U-Pb and detrital apatite U-Pb and fission track age data from Cenozoic sedimentary successions (54–0 Ma) in the northern margin of the Tarim Basin and integrates these data with published provenance data from adjacent regions. Our results show that deformation/uplift of the Baicheng-Kuqa Depression and the South Tianshan occurred at ∼41–37 Ma and ∼24 Ma, when topographic growth of South Tianshan began to block the flow of sediment from the north. Continued uplift of the South Tianshan completely blocked fluvial transport from the Central Tianshan-Yili Block by ∼10 Ma, as shown by the paucity of 380–310 Ma detrital zircons/apatites. Far-field, north-directed compressive stress resulting from the India-Asia collision began to propagate toward the South Tianshan and its foreland during the Late Eocene, and continued to propagate into the South Tianshan and northward at the ∼24 Ma and 10 Ma. Finally, we suggest a two-stage of aridification in the Tarim Basin which can be linked to two stages (∼24 and 10 Ma) of growth of the Tianshan.