The Dras arc: two successive volcanic events on eroded oceanic crust

Abstract The Dras arc is recognized as a volcanic arc system in the western part of the Indus suture zone and it constitutes the link between the Ladakh batholith and the Kohistan arc. This study is based on detailed mapping of the area between Dras, Kargil and Sanku which revealed the following: 1. (1) The ultramafics of Dras and Thasgam can be followed across the Suru Dras ridge and are not intrusive into the arc volcanics, but instead constitute the most probably oceanic substratum of these volcanics. 2. (2) Successive volcanic events are distinguished: 2.1. (a) Dras I is a variable volcaniclastic series rich in slates and carbonates, which can probably be assigned to the Albo-Cenomanian, as dated by orbitolines. This series is intruded by gabbro, diorite and granite and is deformed, essentially in the northern part. It is unconformably overlain by 2.2. (b) the Dras II pyroclastics which grade southward into volcanic breccia and thus enable the location of the centres of volcanic activity during this younger period.