Are the Himalayas volcanic in origin?
Not far from here as the crow flies, at 14200 ft near a village called Langzha, is a big plain of fossils which indicate that a few million years ago it was part of the sea bed.
If I start a thread with a link to a page on another site (an Indian motoring and travel site), will it be allowed or will I be zotted? On the same thread, a travelogue of what is called the "Spiti Loop", you can see some of the fossils. The bigger and better ones have already been collected by travellers and the inhabitants of the villages.
Years ago I worked for a college textbook company. We published a book on plate tectonics ... I spent so much time on the road with those companies that I read practically every good textbook we published. Plate tectonics was not well received thirty-five years ago. Now, it is quite clear that plates subduct and rise. The Appalachians are old mountains, but the Himalayans are new.
More than one massive volcano has erupted in the area which is now Indonesia. A super volcano can send an awful lot of ash to coat the landscape. And as the Himalayas have risen, they have perhaps covered and subducted massive volcanos which ruled prior to the plates forming up the massive risers of the Himalayas. The Yellowstone super volcano may be going extinct due to plates shifting away from the weak spots in sub-crust.
Oh yeah, in answer to your question, IIRC the himalayans are not volcanic in origin, they are the result of a plate over riding another older plate, pushing up material like a ribbon. Place a bath towel on a smooth table top. Push one side of the towel and watch as wrinkles rise up between your hands and the opposite side of the towel. That’s an illustration of how plates rise and subduct.