Focused modern denudation of the Longmen Shan margin, eastern Tibetan Plateau

摘要: We use river sediment load data to map the pattern of modern denudation across Longmen Shan margin Tibetan Plateau. Suspended load, with corrections bed and solute contributions, is used calculate watershed-averaged rates. Decadal erosion spatially heterogeneous, seasonally modulated by monsoon flows, which account for 80–90% load. Enhanced occurs in a ∼50 km wide band on hanging wall Huya fault zones, reaching 0.5–0.8 mm/yr. These rates are similar kyr-scale deduced from cosmogenic 10Be Myr-scale low-temperature thermochronology. The flux-derived decrease increasing distance plateauward, less than 0.05 mm/yr at ∼200 northwest foot Shan. gradient precipitation this alone cannot explain one order magnitude spatial difference erosion. Rather, delineates zone relatively rapid around active faults that carry their wall. From similarity measured over Myr, kyr, decadal time scales, we propose has approached flux steady state. erosional efflux balanced advection rock toward above ∼20°NW dipping ramp margin-bounding fault. Our results suggest high amounts landslide material mobilized earthquakes such as Mw 7.9 2008 Wenchuan event gradually removed rivers, smoothing time. also caution should be exercised when interpreting young cooling ages evidence initiation plateau uplift. Advection an already into belt higher rate could give rise abrupt history.