Well within the mainstream Plate Tectonics theory the next mechanism of mountain ridges formation can work: "When an oceanic plate is getting subducted, what would happen to a divergent boundary on the subduction? The divergent boundary is a very thin, not yet fully solidified, highly irregular, and, therefore, weak juncture between plates. The bending stress of subduction would just cut loose the subducting chunk off the plate. The loose chunk would pop-up along the viscous border of the continent to form a mountain ridge. Other divergent boundaries and, probably, other irregularities in the plate would add more ridges to the continent." http://divergent-bou...keeping-it.html
So, in my opinion, Himalaya formation may not necessarily depend on India's pressing the crust up.
Regards,
Sergey S.
http://divergent-bou...s.blogspot.com/
