Presence of two plume-related volcanic events along the Indian northern passive margin evidenced by the geochemistry of the Carboniferous Baralacha La dykes, the Permian Panjal traps and the Drakkar Po phonolites

The built-up of the Himalayan Ranges is related to the collision of the Indian and Asian plates which occurred 52 Ma ago. Subduction-related magmatism developed, south of the Tibet block while the Indian northern margin remained passive. During the collision, the Indian northern margin was dismembered in several tectonic units, caught between the High Himalayan Cristalline domain and the Indus-Zangbo suture. These tectonic units are largely exposed in the Zanskar, Spiti and Upper Lahul areas in north-western Himalayas. The pre-rift units consist of platform-type detritic sediments ranging in age from the Late Precambrian up to the mid to late Permian; they are characterized by four magmatic events, i.e., the Cambrian to Ordovician granites, the Baralacha La Carboniferous basaltic dykes, the Yunam Early Permian intrusives and the Middle Permian Panjal traps. The latter are related to the Neotethys opening. In the Indus-Zangbo suture, blocks of Late Permian phonolites associated with reefal limestones represent the remnants of the oceanic basin neighbouring the northern Indian passive margin.