Abstract

The Palawan metamorphic terrane, represented by Paleozoic basement on the northwestern tip of Panay, central Philippines, collided with the remainder of the island between late Oligocene and middle Miocene time. Subduction continued north and south of the collision zone, along the Manila and Negros trenches, respectively. Evidence for the collision is (1) the juxtaposition along a major fault of old melange terrane against highly metamorphosed Paleozoic continental sediments similar to those exposed on Palawan island itself, and (2) Miocene thrusting in the melange terrane oriented parallel to the suture.

Paleomagnetic studies show that since the early Miocene the island of Panay has rotated 20° clockwise (declination 20.9°, inclination 22.1° for six sites), whereas the northern Philippines has rotated counterclockwise. These contrasting rotations are consistent with a collision of the Philippine arc with a northeastward-converging Palawan block.

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