Washington: It is well understood that the collision between India and Eurasia led to the formation of the Tibetan Plateau that has an average elevation of 5 km and a much thickened crust.
However, the mechanisms responsible for both the topographic uplift and the crustal thickening remain controversial.
Now, Xiaodian Jiang and colleagues at the Dept. of Marine Geology, Ocean University of China, have obtained high-resolution seismic reflection data from the West Kunlun Range Front at the northwestern margin of the Tibetan Plateau that show that crustal structures there are dominated by nappes of upper crustal rocks.
Horizontal shortening in the upper crust by brittle folding and faulting correlates positively with crustal thickening, an increase in Moho depth, and the topography.
Their work thus suggests that upper crustal shortening is a chief factor for topographic uplift and crustal thickening at the northwestern margin of the Tibetan Plateau.
The researchers believe this mechanism might have played a major role in crustal thickening and proto-plateau uplift during the early stage of continental and terrane collisions in Tibet, which laid the condition for other mechanisms, such as crustal flow, to kick in during late Cenozoic plateau propagation.