Cagayan Valley Basin, North Luzon, Philippines: subduction, rotation and rift product?

Abstract Recent investigations confirm the existence of a west-dipping Cretaceous-Paleogene subduction zone offshore of North Luzon. This tectonic feature can account for the formation of an Eocene arc that subsequently separated into the Central Cordillera Arc and Northern Sierra Madre Range. The separation led to the formation of an inter-arc basin, the Cagayan Valley Basin. The termination of arc splitting that led to the failed rifting of the Cagayan Valley Basin can be attributed to the collision and eventual subduction of an oceanic plateau. This subducted oceanic plateau would not be the Benham Rise but an older one that could be the “counterpart” plateau of the Oki-Daito Rise. The interaction of this subducted plateau with a metasomatized mantle could also account for the alkalic rock-hosted gold-copper deposits and the almost wedge-shaped basin configuration which is wider at the northern portion of the basin and tapers in the southern part around the Caraballo Mountain Range.