The Philippine Archipelago located along the border between the sialic Asiatic mainland and the simatic Pacific basin forms the southern segment of the western circum-Pacific mobile belt. Typical island arc features are well developed in the southern part of the Archipelago.

Most of the Philippine islands appear to be closely related geologically and to have geologic affinities with Taiwan, Borneo, and the other islands of the Indonesian Archipelago. These affinities include similarities in the quartz-deficient basement suites and in ages and characteristics of younger sediments.

Thick accumulations of sediments of Miocene and Pliocene ages are present in most large Philippine basins. Paleo-environmental studies of the Central Valley basin in Luzon have established that the basal deposits were deposited in paralic environments. These sediments grade upward into bathyal deposits which, in turn, grade upward into paralic and continental deposits. Richly organic, bathyal mudstones are possible source beds and the coarser clastic facies (both paralic deposits and turbidites) as well as biohermal limestones have reservoir rock characteristics in outcrop. Other basins with comparable marine sections have Eocene and possibly Cretaceous objectives.

The Philippine rift, the major structural feature in the Philippines, resembles the San Andreas rift in California. It can be traced southward from Northern Luzon through Mindanao. Structural trends are oblique to the rift with the expectable orientation of secondary structures arising from left-lateral movement along the rift. The amount of displacement is not known.

Many oil seepages originating in Miocene and Eocene rocks were investigated during the initial phase of Philippine exploration. Although some companies continue these operations, several are using modern techniques to evaluate deeper prospects. Three discoveries have been made in sandstones and a limestone of Miocene age. The results of drilling to date suggest that delineation of potential reservoirs is the most difficult task confronting exploration in the Philippines.

The Republic of the Philippines is now spending about 90 million dollars annually for imports of crude oil. The internal demand is accelerating and foreign exchange reserves are low. A major discovery will alleviate this serious financial problem.

End_of_Article - Last_Page 273------------