HR: 1340h
AN: T23D-1636    [Abstracts]
TI: Denudation of Actively Growing Mountain Ranges in the Foreland of NE Tibet Inferred From in- Situ Produced Cosmogenic Be-10
AU: * Palumbo, L
EM: luigi.palumbo@uni-muenster.de
AF: Geologisch-Palaeontologisches Institut, Westfaelische Wilhelms, Muenster University, Correnstrasse, 24, Muenster, 48149, Germany
AU: Hetzel, R
EM: rahetzel@uni-muenster.de
AF: Geologisch-Palaeontologisches Institut, Westfaelische Wilhelms, Muenster University, Correnstrasse, 24, Muenster, 48149, Germany
AU: Tao, M
EM: Mxtao@ires.cn
AF: College of Resources Sciences and Technology, Beijing Normal University, N.19, Xinjiekouwai Street, Beijing, 100875, China
AU: Li, X
EM: lxbyj163@163.com
AF: College of Resources Sciences and Technology, Beijing Normal University, N.19, Xinjiekouwai Street, Beijing, 100875, China
AB: At the northeastern edge of the Tibetan Plateau ranges bounded by active thrust faults offer the unique opportunity to study the competing effects of uplift and erosion during the early stages of mountain building. Owing to along- strike variations in relief, slope, and lithology, these ranges are an ideal target for studying the influence of topography, lithology, and active faulting on denudation. Here we report spatially-averaged erosion rates for catchments situated along two of these ranges based on Be-10 concentrations of quartz in stream sediments. The Yumu Shan and the western Long Shou Shan are about 60 km long and their overall shape as well as the presence of wind gaps illustrates their vertical-lateral growth during Plio-Quaternary thrust faulting (Hetzel et al. 2004a). Erosion rates determined so far for 20 small catchments are variable and range from 20 to 550 mm/kyr. The observed variability results from at least three factors: (1) the erosion rate in catchments exposing the same lithology is positively correlated with relief and mean slope, (2) weakly consolidated Cretaceous sediments generally erode faster than low-grade Paleozoic bedrock, and (3) the erosion rate seems to decrease from the centre of the fault-bounded ranges towards their propagating tips. As rates of thrust faulting and rock uplift in the region (600-1200 mm/kyr; Hetzel et al., 2004a, b) exceed the denudation rates, the active growth of mountains and the lateral growth of Tibet has not yet come to rest. References Hetzel, R., Tao, M., Niedermann, S., Strecker, M.R., Ivy-Ochs, S., Kubik, P.W., Gao, B. (2004a). Implications of the fault scaling law for the growth of topography: Mountain ranges in the broken foreland of NE Tibet, Terra Nova 16, 157-162. Hetzel, R., Tao, M., Stokes, S., Niedermann, S., Ivy-Ochs, S., Gao, B., Strecker, M.R., Kubik, P.W. (2004b). Late Pleistocene-Holocene slip rate of the Zhangye thrust (Qilian Shan, China) and implications for the active growth of the northeastern Tibetan Plateau, Tectonics 23 (6), TC6006, doi:10.1029/2004TC001653.
DE: 1815 Erosion
DE: 4918 Cosmogenic isotopes (1150)
DE: 8175 Tectonics and landscape evolution
SC: Tectonophysics [T]
MN: 2007 Fall Meeting