Development of major structures across the northwestern Himalaya, India

Abstract

The Himalaya originated as a result of subduction of the Tethyan oceanic crust that lay between India and Tibet followed by continent-continent collision. A petrotectonic assemblage of the subduction complex consisting of the Shergol ophiolitic melange, the Nidar ophiolite, the Nindam flysch Formation and blue-schist rocks were obducted over the Indian margin during initial collision of the Indian continent with Tibet in the middle Eocene. The collision was followed by continued convergence of India against Tibet resulting in crustal shortening both in the Indian and the Tibetan margins. This crustal shortening produced regional metamorphism and polyphase deformation of the Higher Himalaya zone, the Tso Morari Crystallines and the Pangong Tso group. Continued convergence produced major folds, nappes and thrusts of the Higher, Tethys and Lesser Himalayas on the Indian plate and the Indus, Shyok and Karakoram zones of the Trans-Himalaya. The major structures include the Main Karakoram Thrust, Zanskar Thrust, Tso Morari dome, Zanskar synform, Sum dome, Kashmir-Chamba nappe, Panjal Thrust and MBT. The compressional phase was followed by an uplift phase in the early Miocene which formed a foredeep to the south in front of the uplifted cordillera. The Siwalik group sediments were deposited in this foredeep and were later folded and faulted. The folds and thrusts in the Outer Himalaya belt are younger than those of other tectonic zones of the Himalaya.