GEOLOGY AND TECTONIC HISTORY OF SOUTHEASTERN LUZON, PHILIPPINES

Southeastern Luzon belongs to the eastern Philippine Mobile Belt. Geol ogical and structural studies revealed that it could be divided into t hree major structural units limited by two subparallel NW-SE trending left-lateral strike-slip faults: the Hilawan Fault in the NE and the m inas Fault in the SW. The North-central Catanduanes Structural Unit (N CSU) is characterized by a Middle to early Late Cretaceous volcanic ar e sequence unconformably overlain by a Middle to Late Eocene volcanic are sequence followed by Early Oligocene intrusives. The Median Struct ural Unit (MSU), limited from the NCSU by the Hilawan Fault, is underl ain by a Late Cretaceous volcanic are sequence followed by two distinc t chaotic sequences from the end of Cretaceous-Paleocene and latest Mi ddle Eocene-earliest Late Eocene. It is limited to the southwest by th e Minas Fault. The Western Caramoan Structural Unit (WCSU), pre-late C retaceous ophiolitic suite unconformably overlain by Late Cretaceous v olcanic are sequence and Middle Eocene limestones are exposed. These s tructural units are overlain by carbonate and detrital sequence from t he Late Oligocene to Pliocene. Constrained by angular unconformities a nd deposition of olistostromes, polyphase left-lateral strike-slip fau lting was recorded since the end of Cretaceous up to the limit of Earl y-Late Oligocene. These faults probably represent the traces of a Prot o-Philippine Fault System in Southeastern Luzon. (C) 1997 Elsevier Sci ence Ltd.