OffshorePhilippines

Philippines Offshore

West Palawan Offshore

On this Canvas autotrace of a seismic line of the NW Palawan offshore, a backarc basin is overlain by a non Atlantic-type divergent margin. The rifting phase and the sag phase of the backarc basin are, easily, recognized, since they are associated to two different realms of subsidence. A differential subsidence, during the rifting phase with formation of half-graben structures filled, mainly, by non-marine sediments and a thermal subsidence, during the sag phase in association with a large marine ingression with periods of relative sea level stability, during which marine sediments and reefs were deposited (see stratigraphy in Page 2). The substratum of northern part of Palawan Island, Mindoro island and the Reed Bank area, contrariwise to the rest of the Philippine archipelago, is continental, suggesting that before oceanic expansion (sea floor spreading) the area (North Palawan block) was attached with the South China mainland.