D&partment des Sciences de la Terre,

Abstract. The structure of the pre-Eocene rocks, considered as the "basement " of the Philippines, has been investigated in the Mindoro-Lubang, Romblon-Tablas-Sibuyan, and North Palawan areas. In the former two areas the same pre-Eocene succession of units is recognized from top to bottom: (1) a pre-Eocene olistostrome; (2) an ophiolitic nappe; (3) a schistose sequence (pelites, sandstones, basic schists and marbles); and (4) a gneissic unit. The nature of the contact between the olistostrome and the underlying units is unclear, but the ophiolite and the schistose sequence form two thrust sheets of oceanic origin thrust upon the gneissic unit that is considered a part of a continental basement called the West Philippines Block. Small-scale structures show that the early deformation stage is characterized by a submeridian (0ø-N40øE) lineation formed in greenschist to amphibolite facies conditions during the thrusting. Kinematic analysis show that the thrusting was from north to south. In North Palawan, metamorphic rocks with similar microtectonic and kinematic characteristics are found. They are overlain by a Late Jurassic olistostrom