HR: 17:00h
AN: T34C-05    [Abstracts]
TI: Quantifying landscape differences across the Tibet plateau: Implications for topographic relief evolution
AU: * Liu, J
EM: liu-zeng@itpcas.ac.cn
AF: Institute of Tibetan Plateau Research, CAS, 18 Shuang Qing Rd, Beijing, 100085, China
AU: Tapponnier, P
EM: tappon@ipgp.jussieu.fr
AF: Institut de Physique du Globe, 4 place Jussieu, Paris, 75005, France
AU: Gaudemer, Y
EM: gaudemer@ipgp.jussieu.fr
AF: Institut de Physique du Globe, 4 place Jussieu, Paris, 75005, France
AU: Ding, L
EM: dinglin@mail.iggcas.ac.cn
AF: Institut de Physique du Globe, 4 place Jussieu, Paris, 75005, France
AB: Because of its extreme high-elevation and low-relief interior with a particularly large areal extent, the Tibet plateau is a unique topographic feature on Earth. How and when it attained its current topography has been the motivation of many studies. In one class of previous studies, the landscape morphology of the plateau has been taken to be a straight-forward reflection of deep seated lower crust and mantle processes. The importance of surficial erosion processes in shaping the landscape, by contrast, has been downplayed. To assess the potential role of such processes, we quantify here the bulk landscape characteristics in representative regions of northern, central and southeastern Tibet. We find that the northern and central parts of the plateau are characterized by positive topography. Internal drainage appears to play a major role in smoothing out the tectonically generated structural relief. The change from the internally drained interior, to the externally drained part of eastern Tibet is accompanied by a transition from low to high relief, and from positive to negative topography. We propose that the evolution of river systems and drainage efficiency coupled with tectonic uplift provides a robust mechanism in explaining the systematic regional differences in Tibetan landscape. This also provides a unifying mechanism for the formation of the low-relief interior, and for the origin of the high-elevation low-relief relict surface in SE Tibet. Our analysis questions the fashionable contention that a continuous pre-uplift low-relief surface first formed at low elevation, extending all the way to the South China Sea shore, before being warped upwards in the Late Miocene-Pliocene by lower crustal channel flow.
DE: 1815 Erosion
DE: 1824 Geomorphology: general (1625)
DE: 8107 Continental neotectonics (8002)
DE: 8177 Tectonics and climatic interactions
SC: Tectonophysics [T]
MN: 2007 Fall Meeting