The Malampaya Sound Group is predominantly composed of chert (Liminangcong Formation), clastics (Guinlo Formation) and scattered limestone units that characterize the North Palawan Block (Zamoras and Matsuoka, 2001). In the Calamian Islands (grouping Busuanga, Coron, Culion and other smaller islands) the Liminangcong Formation is represented by Permian to Late Jurassic chert; the Guinlo Formation is represented by Middle-Late Jurassic to Early Cretaceous clastics.
The common succession from chert to clastics with generally conformable contact is thus referred to as a chertclastic sequence. In Busuanga Island, linear topographic patterns reveal the parallel distribution of chert-clastic sequences dipping generally NW in the west, and NE in the central and eastern portions. This chert-clastic repetition indicates an imbricate structure typical to offscrape accretion complexes.