Basement of the sequence in Ilocos; unconformably overlain by the Bangui Formation
Suyo, Burgos, Ilocos Norte
Suyo Metamorphics (BMG, 1981)
The Suyo Schist, exposed largely in Suyo, Burgos, Ilocos Norte, consists of amphibolite, quartz-biotite schist, actinolite-tremolite-talc schist and quartzite which are mostly in fault contact with serpentinized peridotite. These rocks are probably of Cretaceous age.
The amphibolite schist is light to dark green, fine to medium grained and is characterized by planar orientation of green amphibole, chlorite, feldspar and quartz. The rock exhibits usually nematoblastic texture with large bluish green amphibole and prismatic, light colored epidote.
The quartz-biotite schist, consisting dominantly of quartz with lesser amounts of biotite, epidote, garnet, hematite and piedmontite, occurs intimately with the amphibolite schist.
The actinolite-tremolite-talc schist, a product of dynamothermal metamorphism, is structurally confined along the contact of the intensely sheared serpentinized peridotite.