Tectonic framework of the Indus and Shyok suture zones in Eastern Ladakh, Northwest Himalaya

Abstract

Three different phases of plutonic-volcanic activity, viz. 1. (1) Cretaceous volcanics of the Dras and Luzarmu formations. 2. (2) Early Tertiary granitoids of the Ladakh plutonic complex. 3. (3) Oligocene acid volcanics and dykes of the Khardung Formation have been recognised in the Ladakh magmatic arc. The Dras Formation of the Indus suture zone and the Luzarmu Formation of the Shyok suture zone were one stratigraphic unit into which granitoids of the Ladakh plutonic complex intruded. The rocks of the Shyok suture zone are interpreted to represent the tectonised remainder of a marginal (back-arc) basin. The closure of the marginal basin occurred at the Eocene-Oligocene time boundary, and crustal shortening was responsible for generation of Neogene 2-mica granites of the Karakoram plutonic complex and regional metamorphism of the Pangong Tso group.