Late Cretaceous Extension within Dras Arc: Sedimentary Evidence from the Nindam Formation, Zanskar Gorge, Ladakh

ABSTRACT The sedimentary record of the Nindam Formation is crucial for reconstructing the composition and tectono-magmatic evolution of the Dras arc, particularly its younger stages that are poorly represented in the volcanic record, as well as its tectonic relationship with the Kohistan-Ladakh arc. New field observations, facies analysis, and petrographic data suggest that the Nindam Formation in the Zanskar Gorge, Ladakh, was deposited in a volcano-bound basin in a submarine- fan environment characterised by a fining-upward stacking pattern. The sediments record the erosion of dominantly andesitic volcanics with moderate input from felsic volcanics, consistent with sediment derivation from an oceanic arc with an active subaerial volcanic centre during a phase of extension. This inferred phase of extension within the Dras arc is consistent with contemporaneous extensional diapirism reported within the Kohistan Arc and with recently proposed southward migration and extension of the Ladakh Arc at the same time. Our results suggest that the Nindam Formation in the Zanskar Gorge preserves the Late Cretaceous dissection of the Kohistan-Ladakh arc during arc extension, potentially linked to Neo-Tethyan slab rollback.