Quantifying landscape differences across the Tibetan plateau : implications for topographic relief evolution
Date of Issue2008
We quantify the bulk topographic characteristics of the Tibet-Qinghai plateau with specific focus on three representative regions: northern, central, and southeastern Tibet. Quantitative landscape information is extracted from Shuttle Radar Topography Mission digital elevation models. We find that the morphology of the Tibetan plateau is nonuniform with systematic regional differences. The northern and central parts of the plateau are characterized by what we suggest to call ‘‘positive topography,’’ i.e., a topography in which elevation is positively correlated with relief and mean slope. A major change from the internally drained central part of Tibet to the externally drained part of eastern Tibet is accompanied by a transition from low to high relief and from positive to ‘‘negative topography,’’ i.e., a topography where there is an inverse or negative correlation between elevation and relief and between elevation and mean slope. Relief in eastern Tibet is largest along rivers as they cross an ancient, eroded plateau margin at high angle to the major strike-slip faults, the Yalong-Yulong thrust belt, implying strong structural control of regional topography. We propose that the evolution of river systems and drainage efficiency, the ability of rivers to transport sediments out of the orogen, coupled with tectonic uplift, is the simplest mechanism to explain systematic regional differences in Tibetan landscapes. Basin filling due to inefficient drainage played a major role in smoothing out the tectonically generated structural relief. This mode of smoothing started concurrently with tectonic construction of the relief, as most clearly illustrated today in the Qilian Shan-Qaidam region of the northeastern plateau. In the interior of Tibet, further ‘‘passive’’ filling, due to internal drainage only, continued to smooth the local relief millions of years after the cessation of major phases of surface uplift due to crustal shortening.
Journal of geophysical research
© 2008 the American Geophysical Union. This paper was published in Journal of Geophysical Research and is made available as an electronic reprint (preprint) with permission of the American Geophysical Union. The paper can be found at the following official DOI: http://dx.doi.org/10.1029/2007JF000897. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.