Middle Cretaceous back-arc formation and arc evolution along the Asian margin: the Shyok Suture Zone in northern Ladakh (NW Himalaya)

40Ar–39Ar dating of volcanic rocks of the Shyok suture zone in north–west trans-Himalaya: Implications for the post-collision evolution of the Shyok suture zone

“…Calc-alkaline to tholeiitic components were reported from Kohistan-Ladakh arc in the north-west trans-Himalaya (Rolland et al, 2000(Rolland et al, , 2002. The pioneering geochronological studies by Honegger et al (1982) showed that the magmatism started at least 100 Ma ago and continued till the continent-continent collision.…”

“…They are in tectonic contacts with the acidic Khardung volcanics, which are overlying the northern flanks of Ladakh batholith and exposed in the form of thick ignimbritic and rhyolitic flows. The western equivalent of the Shyok volcanics, the Chalt volcanics are thought to be of island-arc or back-arc type (Sharma, 1987;Rolland et al, 2000). On the basis of Chalt volcanics in northern Pakistan and Dras island-arc volcanics in southern Ladakh, it was suggested that Shyok suture is the manifestation of collision between island-arc and south Asian plate prior to the main Indian-Asian collision (Honegger et al, 1982;Reuber, 1989;Petterson and Windley, 1985;Treloar et al, 1996;Clift et al, 2000;Dunlap and Wysoczanski, 2002).…”

“…On the basis of Chalt volcanics in northern Pakistan and Dras island-arc volcanics in southern Ladakh, it was suggested that Shyok suture is the manifestation of collision between island-arc and south Asian plate prior to the main Indian-Asian collision (Honegger et al, 1982;Reuber, 1989;Petterson and Windley, 1985;Treloar et al, 1996;Clift et al, 2000;Dunlap and Wysoczanski, 2002). However, studies by Rolland et al (2000) demonstrated that the island-arc rocks grade into more differentiated acidic rocks towards the eastern part of the suture zone in Ladakh region of India. He suggested progressive maturation of arc towards the east and finally merging into continental arc of Tibet-Lhasa block.…”

K-Ar ages of biotite and muscovite from Pangong metamorphic complex, Shyok suture zone, India: Implications for the youngest post-collision metamorphic event in Ladakh Himalaya

“…The highestgrade gneiss has undergone migmatization, which led to the generation of in situ injection granite known as the Pangong Injection. Rolland et al (2000Rolland et al ( , 2002 suggested that the Pangong metamorphic complex consist of two tectonic units: central granulite facies core and amphibolitic cortex. The granulite facies core of Pangong Range is mainly comprised of metabasites and limestones, while the amphibolite facies cortex consists of pelitic schist, gneisses and minor metabasic rocks found as decametre to hectometre -scale lenses.…”

“…Searle et al (1999) considered that the collision between Ladakh arc and Karakoram took place during the Late Cretaceous to form the suture zone. On the other hand, Rolland et al (2000) presented evidences of subduction and back -arc tectonic setting of volcanic rocks in Skardu, Kohistan, northwest Shyok suture zone, and active margin environment in the volcanics of Nubra river, Shyok suture zone, K -Ar ages of biotite and muscovite Ladakh Himalaya. However, it is not clear evidence to support the subduction process in Shyok suture, Ladakh Himalaya.…”