Research Fellows Directory
Dr Shihu Li
The Tibetan Plateau is more than 4000 m above sea level. It formed when the continents of India and Asia collided and is the best example of how mountain belts form. Knowing when the Tibetan Plateau formed is important to understand (1) how Earth’s continental crust deforms and (2) the link between plateau formation and climate change since it is thought that uplift of the plateau resulted in climate change. It is difficult to make direct determinations of the amount of crustal strain that has occurred, and the timing of surface uplift, over geological timescales. Along the southeast margin of Tibetan Plateau, the deeply incised Salween, Mekong and Yangtze Rivers show an unusual geometry, their drainage basins have near parallel trends and are in considerably closer proximity than would be expected from rivers of this size, which has been ascribed as either due to crustal strain, of which the antecedent rivers would then be passive markers (Hallet and Molnar 2001) or the result of river captures due to plateau uplift (Clark et al. 2004). These two models can be distinguished by investigating the dated sedimentary records of these rivers preserved in their drainage basins.
We will study the Cenozoic paleo-Red river deposits preserved in the Gongjue and Lanping-Jianchuan basins. We will first date the deposits to provide a temporal framework. Then we will use isotopic provenance techniques to assess if and when the major drainage capture occurred. This would be represented in the sediment record by a change in composition of the sediment at the time when the upper reaches of the proposed paleo-Red river were diverted to the Yangtze River. In this way we will assess (a) whether drainage capture occurred, and therefore if the drainage configuration can be used either as passive markers of crustal strain or to document the timing of plateau uplift and (b) the timing of plateau uplift, if a drainage capture occurred.
Interests and expertise (Subject groups)