Ongoing India–Asia convergence controlled differential growth of the eastern Tibetan Plateau

Abstract

The eastern Tibetan Plateau is known for its unique topography and active tectonics, serves as a crucial region for investigating geodynamics and lithosphere–atmosphere interaction. Despite its importance, the formation process and geodynamics of this region remain controversial. We integrated new and reported thermochronological data, and paleo-crustal thickness reconstruction to explore the tectonic deformation, climate–tectonic coupling, and geodynamics of the area. New apatite fission track data, collected from the upstream areas of major rivers in the eastern Tibetan Plateau, revealed multiple rapid river incision phases during the Eocene and Neogene–Quaternary. Apatite (U-Th)/He data obtained from a borehole near the Gaoligong shear zone indicates that the Yingjiang fault experienced two rapid exhumation phases, which initiated at ∼22 Ma and ∼18 Ma, respectively. Thermo-kinematic modeling (Pecube), based on multiple thermochronometers, predicted three phases of thrusting along the Longmenshan fault, which were initiated at ∼34 Ma, ∼17 Ma and ∼14 Ma, respectively. During the late Eocene period, Sr/Y and (La/Yb)n ratios suggest that the eastern Qiangtang and Songpan–Ganzi terranes underwent considerable uplift, followed by outward uplift in the collisional front zone and the southeastern margin of the plateau during the late Oligocene. Paleo-crustal thickness reconstruction also indicate another ∼1 km surface uplift during the Neogene–Quaternary. Our findings, when combined with reported thermochronological data, suggest that during the Neogene–Quaternary, the collisional front zone and the eastern margin of the plateau underwent greater exhumation compared to the eastern Qiangtang and Songpan–Ganzi terranes. The temporally and spatially varied exhumation shaped the landscape of the eastern Tibetan Plateau, driven mainly by precipitation-related erosion and promoted by fold-thrust and strike-slip thrust. This was controlled primarily by eastward lithosphere/asthenosphere extrusion associated with ongoing India–Asia convergence.