HR: 1340h
AN: H43C-0377    [Abstracts]
TI: Geomorphic controls on chemical weathering rates in the High Himalayas of Nepal
AU: * Gabet, E
EM: manny.gabet@mso.umt.edu
AF: University of Montana, Dept. of Geology, Missoula, MT 59812 United States
AU: Langner, H
EM: heiko.langner@umontana.edu
AF: University of Montana, Dept. of Geology, Missoula, MT 59812 United States
AU: Burbank, D
EM: burbank@crustal.ucsb.edu
AF: University of Santa Barbara, Dept of Geological Sciences, Missoula, MT 59812 United States
AU: Barros, A
EM: ana.barros@duke.edu
AF: Duke University, Civil and Environmental Engineering, Missoula, MT 59812 United States
AU: Pratt-Situala, B
EM: pratt@crustal.ucsb.edu
AF: University of Santa Barbara, Dept of Geological Sciences, Missoula, MT 59812 United States
AB: Evaluating the competing roles of climate and topography in controlling chemical weathering rates is critical to understanding the linkages between tectonic activity, surface processes, and the atmosphere. Rivers issuing from ten watersheds in the Annapurna region of Nepal, with drainage areas ranging from 6 to 2700 sq-km, were monitored during the 2002 monsoon season to estimate discharge and to collect weekly water samples. Chemical denudation rates of bedrock were estimated from the cation and anion load. We find a strong inverse linear relationship (r-sqrd = 0.83) between rates of chemical denudation and average watershed hillslope angle. We propose that this relationship is due to the effects of soil depth (ie. steep slopes = thin soils, gentle slopes = thick soils) on chemical weathering rates in an interface-limited weathering environment. These results also support Gilbert's hypothesis on the relationship between soil depth and the rate of soil production.
DE: 1815 Erosion and sedimentation
DE: 1824 Geomorphology (1625)
DE: 1030 Geochemical cycles (0330)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting