River inverse modeling of the late Cenozoic uplift history of the Pamir-Tian Shan orogens: Implications for aridification of Central Asia

The uplift history of the Pamir-Tian Shan orogens remains debated, and is crucial to understanding the aridification of Central Asia. To address this question, we performed inverse modeling of the westward-flowing Vakhsh River along the Alai Valley between the Pamir and Tian Shan orogens. We validated the application of this method in reconstructing uplift history of mountains with complex climatic and tectonic settings. The modeled results reveal three episodes of accelerated uplift of the Vakhsh River drainage at ca. 10–7 Ma, ca. 5 Ma, and 2–0 Ma. The late Miocene rapid uplift at rates of 0.6–0.8 mm/yr of the Vakhsh River drainage occurred at ca. 10–7 Ma. Rock uplift, coeval with compressional deformation and exhumation around the Alai Valley, was likely driven by crustal shortening during the Pamir-Tian Shan convergence. Narrowing of the Alai Valley started to impact westerly atmospheric flow, leading to incipient rain shadow responsible for emergence of desert in the proximal leeward Tarim Basin. Accelerated uplift at ca. 5 Ma and 2–0 Ma at rates of 1.0–1.4 mm/yr and 1.7–2.3 mm/yr, increased surface elevations to near modern heights (3.5–5 km) that largely blocked the westerlies, causing enhanced aridification in the Tarim Basin. Our modeling results highlight the important role of mountain building in shaping late Cenozoic climate in Central Asia. [Display omitted] •Study examines the uplift history of the Pamir-Tian Shan convergence zone.•Applies river channel profile inversion method•River inverse modeling can be used in complex climatic and tectonic settings.•Three episodes of accelerated rock uplift has occurred in the late Cenozoic.•Highlights mountain building as a key mechanism for Central Asia aridification