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Dorr Lecture: Megamountains, Megarivers, and Megafloods: the Sedimentary Archive of Eastern Himalayan Tectonics and Erosion

Katharine Huntington, University of Washington
Friday, March 13, 2020
3:30-4:30 PM
1528 1100 North University Building Map
The Tsangpo gorge region of the far eastern Himalaya is a spectacular feature of the Earth’s crust, where erosion of the Yarlung-Siang-Brahmaputra river has sliced a narrow gorge between two >7 km Himalayan peaks in a zone of extremely localized rapid erosion and rock uplift. It has been argued that this area represents some of the best evidence for a localized positive feedback between river erosion and deformation on Earth. We test this hypothesis by using detrital geochronology and thermochronology of modern river sediments and Cenozoic foreland basin deposits to establish the relative timing of river capture and the onset of rapid erosion/exhumation. Results rule out 3-4 Ma river capture or Quaternary climate change as triggers for rapid exhumation, and instead point to a tectonic driver for extreme rock uplift rates. We investigate the mechanisms by which fluvial erosion keeps pace with rock uplift in different climate regimes using zircon U-Pb and single-grain feldspar luminescence dating of single-event deposits from historical dam-break outburst floods and ancient glacial megafloods. Together with field observations and numerical modeling of flood hydraulics, these data shed light on megaflood provenance and the role of large, infrequent geomorphic events in shaping landscapes—with implications for the sedimentary record of Himalayan tectonics and erosion preserved in Earth’s largest submarine fan
Building: 1100 North University Building
Event Type: Lecture / Discussion
Tags: Lecture
Source: Happening @ Michigan from Earth and Environmental Sciences