HR: 0830h
AN: T21C-0470    [PDF]
TI: Stability of Major River Knickpoints Throughout the Himalaya: Evidence for Strong Coupling Between Erosion and Rock Uplift
AU: * Hallet, B
EM: hallet@u.washington.edu
AF: Quaternary Research Center, University of Washington, Box 351360, Seattle, WA 98195 United States
AU: Finnegan, N J
AF: Quaternary Research Center, University of Washington, Box 351360, Seattle, WA 98195 United States
AU: Anders, A
AF: Quaternary Research Center, University of Washington, Box 351360, Seattle, WA 98195 United States
AU: Koons, P O
AF: Department of Geological Sciences, 5790 Edward T. Bryand Global Sciences Center University of Maine, Orono, ME 04469-5790 United States
AU: Fletcher, R C
AF: Department of Geosciences, University of Pennsylvania 335 Deike Building, University Park, PA 16802 United States
AU: Montgomery, D R
AF: Quaternary Research Center, University of Washington, Box 351360, Seattle, WA 98195 United States
AB: For nearly 2000 km, the Himalaya forms a remarkably continuous and smooth arc at the boundary between India and Tibet. We use this arc as reference line to quantify the mobility of knickpoints of the major rivers and the underlying connection between fluvial incision and bedrock uplift throughout the range. The nearly perfect alignment suggests that knickpoints have not migrated more than 50 km during the 40-50 million years since the initial topographic expression of the collision between India and Eurasia was established. This is an order of magnitude less than the migration expected in the absence of localized tectonic uplift in regions of rapid erosion. For this migration to be limited to 50 km, rates of bedrock uplift and incision must be equal, to within 2% of each other, over the life of the orogen. The close erosion-uplift balance is also evident in the syntaxial corners that terminate the Himalayan arc, where the largest, most energetic and, by inference, most erosive rivers in the region slice through the Himalaya. In these syntaxes, the elevated fluvial incision rates are balanced by focused vertical displacement into the corner massifs. This balance constitutes a spectacular and pervasive example of self-organization emerging from diverse feedbacks between erosional and tectonic processes.
DE: 1824 Geomorphology (1625)
DE: 8102 Continental contractional orogenic belts
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 9320 Asia
SC: Tectonophysics [T]
MN: 2003 Fall Meeting