Structural variety and tectonic evolution of strike‐slip basins related to the Philippine Fault System, northern Luzon, Philippines

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Abstract
The northern part of the Philippine fault zone, in Luzon, corresponds to a complex braided system of left‐lateral strike‐slip faults. The NW oriented main active branch, which emerges from the Philippine Sea, splits into an array of north striking splays responsible for the tectonic evolution of the Central Cordillera. This complex fault pattern has favored local stress field variations. Strike‐slip basins have evolved in this framework along or in the vicinity of the main splays of the Philippine fault. Apart from the classical pull‐apart tectonics on a releasing fault termination, overlap, or bend, we describe other mechanisms such as the strike‐slip tilting or the warping of a strip limited by two strike‐slip faults. The strike‐slip basins are good recorders of the evolution of the Philippine fault system. Those located along the north striking cordilleran faults individualized in late early Pliocene to Pleistocene time when the present‐day Philippine fault initiated, but their main control is the fault shape acquired in upper middle Miocene time. The recent tectonic evolution of the fault system is best recorded in central Luzon, where the active basins trace an asymmetrical V shape, with the longest branch trending NE parallel to the East Luzon Trough, and the shortest one trending NW related to the Philippine fault. Both the fault pattern and the basin distribution demonstrate the influence of the Benham Rise in the tectonic evolution of Luzon. The structural setting is interpreted as the result of an early Miocene collision event between the Benham Rise and the eastern margin of Luzon, and subsequent inception of the NW striking strand of the Philippine fault. The present locations of the basins result from the interaction between the structural heritage and the present‐day regional plate motion.