Contrasted to various other plate boundaries, the Himalaya and also the remainder of India seem awfully quiet as soon as it concerns Volcanism. Sure tbelow are a few small ones and some better north in Tibet, yet compared to the Pacific Ring of Fire, Italy or the East African Rift, contemporary India seems practically dead in that regard.
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That is because in the Himalayas, a continental plate is pumelted under a continental plate, while in the ring of fire, oceanic plates are submerged. These are a lot heavier and sink deeper, hence melt less complicated. The composition of the material, including a lot of water, then provides the molten surconfront of the subunified oceanic plate fairly 'volatile' (for the absence of a far better word), so it ascends and develops volcanoes. Continental crust is pushed quite level under the top continental crust given that both crusts have actually a fairly light density, so the surconfront is not heated up as much and also does not sear through the layers above.
This is certainly on the appropriate track, yet I'll add a couple of clarifying points. Water content within a slab of subducting oceanic crust is without question a major driver of the melting that eventually drives formation of volcanoes in convergent settings (these strings of volcanoes that form inboard of subducting oceanic margins are generally referred to as "volcanic arcs"), but the mechanism explained is not rather ideal. The subducted slab itself is not "molten", it's actually fairly cold compared to the neighboring crust and also mantle versus which it is juxtaposed, however various procedures execute cause the water within the subudcting slab (both within the sediments on the top of the slab, however additionally within the top components of the basaltic oceanic crust) to be expelled and also migrate upwards, into the wedge of mantle material over the subducting slab. This water efficiently lowers the melting temperature of the product in this wedge and also within the lower components of the crust leading to the formation of melts, which will certainly move upwards and inevitably form volcanoes. This dehydration of the slab happens at a particular set of depths, generally between 100-150 km and for this reason the place of the volcanic arc that forms have the right to tell you something about the angle of the subducting slab.
Getting ago to why there are few volcanoes in the Himalaya, the answer over is mainly correct in that the underthrusting of continental crust beneath continental crust does not typically geneprice melts in the exact same fashion as you view in oceanic subduction, mainly bereason of the absence of water. So you don't see a volcanic arc in continental collisions frequently. That being said, mountain building processes carry out geneprice most heat which can inevitably result in partial melting. This deserve to at some point lead to volcanic systems occurring, will absolutely bring about the advance of large igneous bodies within the mountain range (i.e. plutons), and also once the core of the mountain variety is exposed numerous years later on, there might also be a fair amount of migmatite an altogether awesome looking rock which documents partial melting of a metamorphic rock.
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For the Himalaya, tbelow are actually extensive volcanic deposits from volcanoes, yet these are mainly > 50 million years old and also were formed prior to the last collision of India and Asia, once tright here was still an ocean basin separating the 2 which was being subducted, developing an volcanic arc as described over.