Folded orogen dissection under conditions of regional compression (with reference to the Pamir-Tien-Shanboundary)

Abstract

Erosional dissection of mountain ridges between the Pamir and Tien-Shan had been profoundly influenced by folding process within the upper 10 km of the sedimentary mantle, displaced and deformed by the tangential pressure of the Indostan plate. As the uplift proceeds, folding processes continue, and valley floors do not keep pace with ridges. At early stages fluvial processes contribute to the relative heights increase, but later they cannot remove all the debris and the latter accumulates in valleys. The balance between the input from slopes and removal by streams is achieved after glaciers formation. Increase in slope angle and valley depth results in development of an optimum cross-profile of the range, usually with narrow crest and rather steep slopes.