Formation of m~langes in the Indus Suture Zone, Ladakh Himalaya by successive subduction-related, collisional and post-collisional processes during Late Mesozoic-Late Tertiary time

Abstract: The classic Indus Suture Zone in western Ladakh includes two zones (southern and northern) of highly dismembered rocks, that in the past were widely interpreted as ophiolitic mrlanges, created mainly by subduction/accretion processes. The 'ophiolitic mrlange ' was reported to include chaotically distributed blocks of ophiolitic rocks (e.g. serpentinite, gabbro, basalt) and sedimentary ocks (chert, limestone) set in a matrix of deep-sea clastic sediments. This accretionary hypothesis tested in this paper and found to be inadequate. Units formed simply by oceanic subduction-accretion (i.e. local mud-matrix m~lange) are minimal ( < 1 % by volume). In reality, the southern and northern mrlange zones are the end products of complex multi-stage tectonic processes, involving subduction (mid-Late Cretaceous to Early Tertiary), initial emplacement (latest Cretaceous), collision (Palaeo-cene Eocene) and post-collisional (Late Tertiary) stages. Important components of the m6lange as a whole include thrust sheets and broken formation of relatively coherent volcanic-sedimentary successions related to the North Indian passive margin (Karamba nd Lamayuru complexes), also mid-Late Cretaceous oceanic ar-type volcanics and volcani-clastic sediments (Dras arc omplex). Dismembered serpentinite hrust sheets, cut by swarm