Geology of Part of Central Ladakh Himalaya with Particular Reference to Indus Tectonic Zone

Abstract

In the Central Ladakh Himalaya, the Ladakh Granitic Complex with Kharbu Group, the Indus Tectonic Zone and the Spiti-Zanskar and Kashmir Precambrian Phanerozoic belts constitute the chief geological units. The Ladakh Granitic Complex comprises a heterogeneous association of granitoids, gabbroids and basic rocks. The Spiti-Zanskar and Kashmir belts comprise Precambrian-Eocambrian crystallines and Late Palaeozoic-Mesozoic sediments.The Indus Tectonic Zone, a name adopted in preference to the Indus Suture Zone consists of two parallel and almost homotaxial sedimentary belts viz., the non-ophiolitic Indus Group in the north and the ophiolitic sedimentary volcanic belt of the Sangeluma Group in the south. The Indus Group unconformably overlies the Ladakh Granitic Complex, and the Sangeluma Group tectonically overlies the former. The Indus Group is divisible into the Skinding, the Kuksho, the Maklishun and the Karit Formations in the ascending order, and the Sangeluma into the Khalsi, the Dras Volcanic, the Nindam and the Shergol Formations with ophiolite association in all the formations excepting the Nindam.

The Indus Group cycle of sedimentation comprises, shallow diamictite, flyschoid, lagoonal and molassic stages, whereas the Sangeluma comprises the platform, submarine volcanic, flyschoid and unstable shelf type sedimentation.

Tectonically, the area can be divided into: Ladakh Granitic Complex-Indus Group autochthon, the Sangeluma parautochthon, the Kuling-Lilang schuppen belt, the parautochthon of Spiti-Zanskar and Kashmir Precambrian-Phaneroxoic belts and Shilakong ophiolite nappe.

The Indus Tectonic Zone was an original mega lineament which later became a site of opening of sea and sedimentation for the Indus and the Sangeluma. A sequence of stages of sea-floor spreading subduction and closing is envisaged.