Late Cenozoic locally landslide-dammed lakes across the Middle Yangtze River

Abstract

Understanding the drainage history of the Middle Yangtze River is critical for determining its interaction of tectonics, climate, and denudation. Previous studies have focused on interpreting the provenance of the Xigeda lacustrine sediments, however, the poorly constrained ages of these sediments mean that the evolutionary history remains elusive. Here, we present new cosmogenic 10Be, 21Ne and 26Al data from the Dadu and Anning river sediments, indicating deposition ages of paleo-lake sediments between ~1 and ~0.5 Ma. Paleo-denudation rates together with neon isotopic composition and topographic analysis suggest that there was no connection between the Dadu and Anning rivers during the Middle Pleistocene. Combined with field investigations and cosmogenic nuclides ages, we suggest that paleo-lakes formed upstream of channel blocking landslides, which in turn could have been the result of external forcings, such as earthquakes, debris flows, increased precipitation, and glaciation. Previous thermochronology data constrain the fluvial incision of the paleo-Dadu-Anning River to have enhanced between ~13–9 Ma. Subsequently, our cosmogenic results show paleo-lakes were formed (~1 Ma) after the paleo-Dadu-Anning River capture (~2 Ma). Finally, the draining of paleo-lakes occurred at ~0.5 Ma.