Jurassic–Cretaceous arc magmatism along the Shyok–Bangong Suture of NW Himalaya: formation of the peri-Gondwana basement to the Ladakh Arc

Abstract

The Jurassic–Cretaceous Tsoltak Formation of the eastern borderlands of Ladakh Himalaya consists of conglomerates, sandstones and shales, and is intruded by norite sills. It is the oldest sequence of continent-derived sedimentary rocks within the Shyok Suture. It also represents a rare outcrop of the basement rocks to the voluminous Late Cretaceous–Eocene Ladakh Batholith. The Shyok Formation is a younger sequence of volcaniclastic rocks that overlie the Tsoltak Formation and record the Late Cretaceous closure of the Mesotethys Ocean. The petrogenesis of these formations, ophiolite-related harzburgites and norite sill is investigated through petrography, whole-rock geochemistry and U–Pb zircon geochronology. The youngest detrital zircon grains from the Tsoltak Formation indicate an Early Cretaceous maximum depositional age and a distinctly Gondwanan, Lhasa microcontinent-related provenance with no Eurasian input. The Shyok Formation has a Late Cretaceous maximum depositional age and displays a distinct change in provenance to igneous detritus characteristic of the Jurassic–Cretaceous magmatic arc along the southern margin of Eurasia. This is interpreted as a sign of collision of the Lhasa microcontinent and the Shyok ophiolite with Eurasia along the once continuous Shyok–Bangong Suture. The accreted terranes became the new southernmost margin of Eurasia and the basement to the Trans-Himalayan Batholith associated with the India–Eurasia convergence.Supplementary material: Supplementary figures and Tables S1–S3 are available at https://doi.org/10.6084/m9.figshare.c.5633162