Philippine plate = "cracked off corner" of Pacific plate?

[Widdekind]

As evidenced by the Emperor - Hawaii island chains, c.45Mya, the northwards-sliding Pacific plate began sliding westwards. If that sudden shift in direction was caused by some massive force (North America obducting east Pacific ridge near San Francisco, so "slamming into" the Pacific plate on the other side of the M.O.R.?), then perhaps the Philippine plate was "cracked off"? The northwards slide of the Philippine plate resembles the ancient northwards trend of the Pacific plate, before c.45Mya.

 

The Philippine plate is c.50 Myr old. 50 Mya, Asia was subducting younger Pacific plate, with older (colder, denser, deeper) Pacific basin farther out to sea. Thus, Asia was obducting "down hill", depressing younger, lighter, higher-riding oceanic crust, attached to older, heavier, lower-riding oceanic basin out-board (sea-wards). Perhaps that caused the in-board (land-wards) corner to "crack off", as the older basin out-board began to subduct the younger oceanic crust, jammed up against the Asian coast ? (Cp. imagine Asia obducting right-to-left, in part B, of this figure; the down-ward depressing, on the right edge, of the right-most slab, could cause the same to rotate clockwise, tilting up over the lip, of the second slab section -- especially with a jarring collision, capable of completely re-directing the Pacific slab nearly 90 degrees, as occurred c.50 Mya. Indeed, the Philippine plate is straight across, on a great circle, from the tip of North America, near San Francisco, which obducted onto the Pacific plate, at that time. Colossal compression waves, emanating from the California coast, could have propagated through the Pacific plate, first "down hill" into the deep Pacific basin, and then "up hill", up slope, through younging oceanic crust, towards Asia. Perhaps at some point, those colossal compression waves found a fault that failed? Alternatively, Asia's collision with India occurred about that time, too.)

 

Edited September 28, 2012 by Widdekind