HR: 0830h
AN: H51D-1089    [PDF]
TI: Relationships Between GIS-Based Erosion Indices and Relief Production in the Karakoram Himalaya
AU: * Bishop, M P
EM: bishop@data.unomaha.edu
AF: Univ. of Nebraska at Omaha, Dept. of Geography & Geology, Omaha, NE 68182 United States
AU: Shroder, J F
EM: jshroder@mail.unomaha.edu
AF: Univ. of Nebraska at Omaha, Dept. of Geography & Geology, Omaha, NE 68182 United States
AU: Bush, A B
EM: andrew.bush@ualberta.ca
AF: Univ. of Alberta, Dept. of Earth & Atm. Science, Edmonton, AL T6G 2E3 Canada
AU: Copland, L
EM: luke.copland@canterbury.ac.nz
AF: Univ. of Canterbury, Gateway Antarctica, Christchurch, 8020 New Zealand
AU: Owen, L A
EM: lewis.owen@ucr.edu
AF: Univ. of California-Riverside, Dept. of Earth Sciences, Riverside, CA 92521 United States
AB: Mountain topography is the result of highly scale-dependent interactions involving climatic, tectonic, and surface processes. Alpine glaciers are known to be effective erosional agents that alter landscape relief-structure differently with altitude, although considerable uncertainty and debate exists concerning their effectiveness relative to fluvial activity. Furthermore, from a geodynamic systems perspective, the role of surface processes and relief production, and the spatio-temporal relationships between erosion and rock uplift are enigmatic. The Karakoram Himalaya represents an excellent location to study such relationships, given the extreme relief and reported values of sediment flux and exhumation rates. Consequently, we utilized GIS-based terrain modeling, global climate model simulations, geochronology, and satellite remote sensing to depict areas of rapid erosion in relation to mountain peaks and zones of rapid uplift, and assess the influence of alpine glaciation and other surface processes on landscape relief-structure. Three-dimensional, scale-dependent analysis and modeling of GTOPO30 data reveals that the maximum Airy isostatic response to landscape dissection ranges from $\sim$ 2 - 3 km for the highest peaks. GIS-based erosion indices depict high-erosion patterns that are spatially coincident with known and suspected zones of rapid uplift and erosion, such as Nanga Parbat, K2 and the Hunza region. The spatial variations depict differences in the coupling of glacier and fluvial erosion, although high-erosion areas exhibit a significant glacier erosion component. Topographic analysis reveals a non-linear relationship between slope angles and altitude, and high-resolution satellite imagery provides evidence of glacier erosion surfaces at high altitude. Although these surfaces have not yet been dated in the K2 region, geochronologic evidence from similar terraces in Hunza support an age of $>$ 100 K BP. If we assume this to be the case, our preliminary maximum estimates of valley incision near K2 average $>$ 1.5 cm / yr. Paleoclimate simulations and glaciological parameter estimates support the interpretation of periodic monsoon-enhanced, high-magnitude glacial erosion in these zones. We conclude that climate forcing and glacier positive-feedback mechanisms can generate significant relief at high altitudes, as deep glacier erosion removes lithospheric mass, whereas high peaks and ridge-lines are protected by permafrost and cold-based ice.
DE: 1815 Erosion and sedimentation
DE: 1824 Geomorphology (1625)
DE: 1827 Glaciology (1863)
SC: Hydrology [H]
MN: 2003 Fall Meeting