Decoupling of erosion and precipitation in the Himalayas

被引:460
作者
Burbank, DW [1 ]
Blythe, AE
Putkonen, J
Pratt-Sitaula, B
Gabet, E
Oskin, M
Barros, A
Ojha, TP
机构
[1] Univ Calif Santa Barbara, Dept Geol Sci, Santa Barbara, CA 93106 USA
[2] Univ So Calif, Dept Earth Sci, Los Angeles, CA 90089 USA
[3] Univ Washington, Dept Earth & Space Sci, Seattle, WA 98195 USA
[4] Harvard Univ, Div Engn & Appl Sci, Cambridge, MA 02138 USA
[5] Himalayan Experience, Kathmandu 3, Nepal
基金
美国国家科学基金会; 美国国家航空航天局;
关键词
D O I
10.1038/nature02187
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The hypothesis that abrupt spatial gradients in erosion can cause high strain rates in active orogens has been supported by numerical models that couple erosional processes with lithospheric deformation via gravitational feedbacks(1 - 3). Most such models invoke a ' stream- power' rule, in which either increased discharge or steeper channel slopes cause higher erosion rates. Spatial variations in precipitation and slopes are therefore predicted to correlate with gradients in both erosion rates and crustal strain. Here we combine observations from a meteorological network across the Greater Himalaya, Nepal, along with estimates of erosion rates at geologic timescales ( greater than 100,000 yr) from low- temperature thermochronometry. Across a zone of about 20km length spanning the Himalayan crest and encompassing a more than fivefold difference in monsoon precipitation, significant spatial variations in geologic erosion rates are not detectable. Decreased rainfall is not balanced by steeper channels. Instead, additional factors that influence river incision rates, such as channel width and sediment concentrations, must compensate for decreasing precipitation. Overall, spatially constant erosion is a response to uniform, upward tectonic transport of Greater Himalayan rock above a crustal ramp.
引用
收藏
页码:652 / 655
页数:4
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