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ABSTRACT: A Middle Miocene Reconstruction of the Philippines and Its Consequences Concerning Petroleum Exploration

Arthur Saldivar-Sali, John Suppe, Richard E. Bischke

The major problem in the Philippines with respect to petroleum exploration seems to be finding the presence and/or the location of good reservoir beds. This problem arises as portions of the Northern and Central Philippines contain typical island arc environments along with continental fragments. Thus in this work, we shall concentrate on the geologic trends and on the location of reservoir sands or reefal build-ups.

The middle Miocene reconstruction of the Philippines is postulated. Briefly, the Continental Palawan-Mindoro blocks collided with the Visayas (which also contains continental affinities) during about the middle Miocene. This collision uplifted Central Mindoro and deformed basement and sedimentary strata along a line that trends from Northern Luzon to Negros. Behind this collision zone and/or trench is an Oligo-Miocene volcanic arc that formed during subduction along the ancestral Manila trench during the Oligocene to the Miocene. This subduction and the resultant tilting of the ophiolitic basement rocks toward the east formed a series of forearc basins along the 570 km long arc-trench system. After the middle Miocene collision, the central Philippines ruptured along the Batangas and C ntral Luzon branches of the Philippine fault system and rotated Central and Northern Luzon 20° in a counterclockwise direction. In this papel, we shall discuss the petroleum implications associated with this reconstruction for the Northwestern and Central Luzon, for the Palawan-Mindoro blocks, and for portions of the Visayas (i.e., Panay, Negros, Cebu, Masbate, and Bohol). Our presentation will draw on work conducted by the Philippine National Oil Company (PNOC) and by work conducted by the Bureau of Energy Development (BED) which, since 1982, has been conducting a basin evaluation study of the Philippine Islands and their offshore basins.

AAPG Search and Discovery Article #90097©1990 Fifth Circum-Pacific Energy and Mineral Resources Conference, Honolulu, Hawaii, July 29-August 3, 1990