The onset of movement on the Philippine Fault in eastern Mindanao: A transition from a collision to a strike‐slip environment

Abstract

The spatial and temporal evolution of eastern Mindanao from a zone of active arc‐arc collision to one of pure strike slip environment is addressed. This is made possible by tracing the Philippine Fault, confined to a well defined and narrow zone of deformation, and by differentiating from it earlier collision‐related compressional features, whose deformation is distributed over a broad zone. A diachronous unconformity marking the end of collision‐related deformation reflects the southward propagating nature of the collision and provides limits on the age of initiation of the Philippine Fault. This diachronism suggests that the initiation of the Philippine Fault is related to the completion of the collision. We show the rapidity at which formation and propagation of the fault follows the locking of the collision zone. We likewise demonstrate that the Philippine Fault reactivates pre‐existing collisional features in cutting across the southern Pacific Cordillera.