Reconciling the Long-Term Growth of the Northeastern Tibetan Plateau and the Upstream Yellow River Profile

Abstract

The growth history of the Northeastern Tibetan Plateau (NETP) is enigmatic, with debates on when and how the NETP significantly uplifted. Here, we use a numerical landscape evolution model to quantitatively investigate the ∼20 Ma growth history of the NETP by studying the formation history of the upstream Yellow River (UYR). The long-term growth history of the NETP consists of an early block uplift (∼20–${12}_{-4}^{+3}$ Ma) and a late outward propagation uplift (${12}_{-4}^{+3}$–0 Ma), compared to the observed river profiles, erosion rates, the trend of acceleration time of deformation, and paleo-elevation data sets. Before ${12}_{-4}^{+3}$ Ma (middle Miocene), the NETP was uplifted via a block growth, with a major uplift in the south part. Subsequently, the high (∼5 km) NETP has been uplifted via a northward propagation until the present. We further suggest that pure headward erosion unlikely formed the observed river profile of the UYR over the past few million years. Our modeling thus reconciles the long-term outward growth of the NETP and the UYR profile, suggesting a downstream migration of high erosion rates, which is fundamentally different from the headward erosion of small mountain rivers. The downstream propagation of fluvial erosion may be common in the outward-growing plateaus elsewhere on Earth.