It seems like that the cool plate subducted into and cut an earlier warmer mantle plume unit from the seismic picture. Whether the relationship is true or faulse?
Good question! The reason might lie in how the subducted slab interacts with the mantle transition zone... as introduced in the film .... though the situation is 3D - so reasons may lie in slab processes adjacent to Japan....
Thankyou Prof. Butler for making such nicely explained videos on Himalayas and Red river fault. Those video clear so many doubts, Actually the Indian plate subduct in. Two direction, one in north under Eurasian/tibetan and one in east under burmese micro plate. Hence I wanted to make a request that can you please make a video on eastern Himalayan syntaxis that why the myanmar itself and the major basins like Assam Arakan (Surma basin) has western convex arch, as if something is pushing them into west whereas subduction is going on east. It's bit confusing
need to explain more in depth/clearly the backwards and forwards and penetration of perovskite , , ie why penetration beyond 600 km? or not ? why backward and forward motion ? - a semi-mystified retired geophysicist
As the slab rolls back it takes the arc with it - so the back arc must stretch...One reason for the slab hinge rolling oceanward is that at depth the subducted slab "ponds" against the mantle transition zone....
The one part, a subdued plate bounces on the 2nd layer is ok, but I am still curous what force can pull the Japanese Area against the in moving Pacific Plate ... if Asia itself is not moving ...
The general idea is that the motor for plate tectonics is slab pull. It can drag down the subducting plate but if the hinge of the subduction zone rolls back, then the over-riding plate (volcanic arc) moigrates with it, causing the area behind to rift (back arc basin). Mainland Asia "pushing" Japan wouldn't generate the rifting of the back arc artea (Sea of Japan)... Incidentally - it's the same reason I think the extrusion of Tibet (see film) is IMO an unlikely driver for basin formation further out in SE Asia... Thanks for the question.
