OffshorePhilippines

Philippines Offshore

NW Sulu Sea

As illustrated on the location map of the seismic line of this Canvas autotrace, the NW Sulu Sea (where the seismic line is located) and SE Sulu Sea, individualized by the Sulu Ridge, are bounded by Borneo to the west, Sulu volcanic ridge to the south, Philippines to the east, and Palawan and Palawan continental terrace to the north. They are episutural (inside of the Meso-Cenozoic Megasuture) marginal or backarc seas formed between the continent and an/or island arcs, associated with an oceanization in the backarc area. The substratum of these marginal seas is the new formed oceanic crust, over which backarc basin sediments, predating the oceanization (breakup of the lithosphere) and sediments of a non Atlantic-type margin (postdating the oceanization) are deposited, as illustrated on this tentative geological interpretation. Actually, in the Western Pacific Ocean a lot of island arc chain and backarc basins with non Atlantic-type divergent margins, i.e. with formation of marginal seas (South China, Banda, Molucca, Celebes, Sulu) were developed, mainly, since the Middle Eocene when India collide with Asia and Australia pressed north toward Sundaland, which seem to represent the final phase of the Neo-Tethys closure (Chun-Kit Lai et al., 2020).