From ka to Ma: A multi-timescale record of accelerating Cenozoic tectonic uplift between the Qilian Shan and Qaidam Basin, northern Tibetan Plateau

Abstract

Constraining tectonic uplift history within the Tibetan Plateau is critical to understanding its deformational response to continental collision. However, it is difficult to extrapolate orogen-scale uplift history from any single method alone. Here, we combined high-resolution deep and shallow seismic imaging (on the order of 103 to 102 meters in depth, respectively) with geologic paleoseismic trenching (on the order of several meters in depth) in the Qilian Shan−Qaidam Basin (QSQB) transition zone within the northern Tibetan Plateau, which provide a fault-to-basin, ka-to-Ma-scale record of mountain building. Tectonic uplift began in the early Cenozoic (>40 Ma), with slow uplift rates persisting until ca. 15.3 Ma. Tectonic tilting with limited thrust faulting along the QSQB transition zone was the predominant form of deformation during this period. Accelerated uplift since the middle Miocene is attributed to the activation of more thrust faults, and an increase in fault vertical slip rates by an order of magnitude, reaching ∼0.2−0.25 mm/a.