N.L. Caagusan’s scientific contributions

... These fragments are set in a highly sheared, metamorphosed matrix. Previous work byCaagusan (1966) describes the metamorphic rocks as essentially low grade, being composed of quartzo-feldspathic schist, gneiss, semischist, phyllite, marble, slate and meta-conglomerate.Caagusan (1966) implies that the schist and other regionally metamorphosed rocks have sedimentary rocks as protoliths (e.g. the quartz feldspathic schist and the semischist have greywacke as sources while the slate and phyllite were derived from the shale and argillite interbedded with the greywacke).Canto et al. (2012) also conclude that the metamorphic rocks were derived from various sources, including clastic, silicic igneous rocks and ophiolitic rocks based on field observations and petrographic studies. Finally, recent expeditions made on the western part of Panay revealed the presence of a tectonic mélange consisting of cherts, ophiolitic fragments as well as metamorphic rocks made up mostly of greenschist and phyllite(Figure 7d). ...

Reference:

Mesozoic radiolarian faunas from the northwest Ilocos Region, Luzon, Philippines and their tectonic significance