Himalayan Geology, Vol. 43 (1B), 2022, pp. 201-220, Printed in India
Tectonostratigraphic framework and the Closing of Neo-Tethys in Ladakh, NW Trans Himalaya, India: A Review
V.C. THAKUR
Wadia Institute of Himalayan Geology, Dehradun - 248001, India
Email: thakurvc12@gmail.com
Abstract: The vast New-Tethys ocean, ≥3000 km wide, was closed as a consequence of subduction of the Indian oceanic lithosphere beneath the southern margin of Asian (Tibet) plate through northward converging movement of India. An intra-oceanic subduction produced the Dras island arc and volcanic arc over the Nidar ophiolite. The subduction beneath the southern margin of Asia generated batholiths of the Ladakh and Karakoram, and rifted apart a microcontinent with opening of the Shyok basin. The ophiolitic melanges of Shergol and Zildat and the Nindam Formation represent the pleoaccretionary prism formed in a trench. The Nidar and Spontong ophiolites are relic of Neo-Tethys oceanic crust. The Indus Formation of Paleocene marine passing upward into the Neogene molasse sedimentary were deposited in an arc-trench gap basin, also interpreted as the fore-arc basin. The Shyok Suture zone lies between the Ladakh magmatic arc and the Karakoram granitic batholith of the Karakorum block. The Shyok basin is formed due to rifting of the southern margin of Asia, splitting the wider magmatic arc into the Ladakh and the Karakoram batholiths. It represents a marginal basin, interpreted as a back-arc basin. The Spongtong ophiolites occur as a detached slab over the Zanskar Tethys Himalaya, derived through intra-oceanic thrusting from the Neo-Tethys ocean. The Indus Suture zone has been extensively investigated by various teams in the last about three decades. A considerable amount of geological and geochronological data has been generated which help in interpretation of the evolution of the Indus Suture zone. An attempt is made here to collate and review the data and present a synthesis in the closing of the Neo-Tethys.
Keywords: Indus Suture, island-arc, magmatic arc batholiths, ophiolitic mélange, subduction, ultra-high-pressure metamorphism, Ladakh
