Testing models of Tibetan Plateau formation with Cenozoic shortening estimates across the Qilian Shan–Nan Shan thrust belt

Abstract

Competing models that account for the construction of the Tibetan Plateau include continental subduction, underthrusting, distributed shortening, channel flow, and older crustal-structure inheritance. Well-constrained estimates of crustal shortening strain serve as a diagnostic test of these plateau formation models and are critical to elucidate the dominant mechanism of plateau development. In this work we estimate the magnitude of Cenozoic shortening across the northern Qilian Shan–Nan Shan thrust belt, along the northeastern plateau margin, based on detailed analysis and reconstruction of three high-resolution seismic reflection profiles. By integrating surface geology, seismic data, and the regional tectonic history, we demonstrate that this thrust system has accumulated >53% Cenozoic strain (∼50 km shortening), accommodated by several south-dipping thrust faults. Based on the observed strain distribution across northern Tibet, including lower strain (30%–45%) within the interior of the Qilian Shan–Nan Shan thrust belt, we suggest that a combination of distributed crustal shortening and minor (