Geology of Nepal

The geology of Nepal is dominated by the Himalaya, the highest, youngest and a very highly active mountain range. Himalaya is a type locality for the study of on-going continent-continent collision tectonics. The Himalayan arc extends about 2400 km from Nanga Parbat (8,138 m) by the Indus River in northern Pakistan eastward to Namche Barwa (7,756 m) by the gorge of the Tsangpo-Brahmaputra in eastern Tibet (Le Fort 1996). About 800 km of this extent is in Nepal; the remainder includes Bhutan and parts of Pakistan, India, and China.

Since 55 Ma the Himalayan orogeny beginning with the collision of Indian subcontinent and Eurasia at the Paleocene/Eocene epoch (Rowley 1996), has thickened the Indian crust to its present thickness of 70 km (Le Fort 1975). The northwest tip of India after colliding with Asia seems to have met along the full length of the suture by about 40 Ma (Dewey et al. 1988).

Immediately prior to the onset of the Indo-Asian collision, the northern boundary of the Indian shield was likely a thinned continental margin on which Proterozoic clastic sediments and the Cambrian ±Eocene Tethyan shelf sequence were deposited (Le Fort 1996).

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