Evolution of the Ladakh Magmatic Arc

Abstract

In this contribution, the evolution of the Ladakh magmatic arc encompassing ca 160 Ma history from subduction initiation to intra-oceanic arc collision to final continent-continent collision is summarized. The observed compositional variation in Ladakh magmatic arc reflects directional maturity from mafic magmatism towards south to more acidic magmatism towards north, and therefore indicating northward dipping subduction. Based on the ca 160 Ma Neo-Tethys geodynamic reconstruction, the evolution of the Ladakh magmatism can be summarized into three distinct time periods; (i) from 160 to 80 Ma, representing intra-oceanic island arc (IOIA) complex dominantly of mafic magmatism, (ii) from 80 to 50 Ma, the magmatism shifts to felsic composition (involving Indian continental margin) in the form of Kohistan-Ladakh batholith and (iii) from 35 to 18 Ma, the magmatism occurred in the form of post-collisional dykes. We also support the double collision model of Ahmad et al. (2008), according to which the first collision occurred between IOIA complex (including Kohistan-Ladakh batholith) with southern margin of Asia during mid-Cretaceous to late-Cretaceous along Shyok Suture Zone (SSZ). Finally, the accreted IOIA and Asian plate margin collided with the northern margin of Indian plate during Late Eocene ∼40 Ma along the Indus Suture Zone (ISZ).