Evaluating triggers for river capture along the Sutlej River, western Himalaya
Abstract
Drainage capture is a ubiquitous phenomenon in the Himalayan orogen, as reflected in numerous barbed drainages and asymmetric basins that extend across the orogen and into southern Tibet. Field evidence and a series of migrating knickpoints in the Zhada Basin of southern Tibet suggest late Pleistocene capture of the basin by the trans-Himalayan Sutlej River. We use a numerical incision model to constrain the incision magnitude and temporal evolution in response to this event. Modeling results, in conjunction with field observations, topographic analyses, and low-T thermochronometry, are used to evaluate two different proposed triggers for drainage capture. First, we examine a potentially Quaternary-active South Tibetan Detachment System (STDS) as a driver of base level fall and subsequent divide migration. While activity along the STDS in the western Himalaya is believed to have ceased in the Miocene, apatite (U-Th)/He ages along the Sutlej River valley suggest differential exhumation across the STDS during the Quaternary. Second, we evaluate the possibility that an earlier capture of a large downstream tributary to the Sutlej (Spiti River) triggered capture of the Zhada Basin. The findings of this work have implications for similar capture events by other trans-Himalyan rivers (e.g. Arun River, Kali Gandaki, Trishuli River). This work is vital to understand how orogenic systems evolve and whether Himalayan drainage reorganization is primarily a product of internal dynamics or tectonic forcings.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMEP0310007P
- Keywords:
-
- 1625 Geomorphology and weathering;
- GLOBAL CHANGE;
- 1815 Erosion;
- HYDROLOGY;
- 8110 Continental tectonics: general;
- TECTONOPHYSICS