Paleomagnetism in an accretionary margin Luzon, Northern Philippines

Abstract

Paleomagnetic results from Northern and Central Luzon reveal clockwise rotated declinations for Late Miocene rocks. This is interpreted as a record of tectonic rotation when Luzon was a part of the Philippine Sea Plate, prior to the development of the East Luzon trench. To the south of Luzon a left lateral shear zone is required to separate it from regions which do not show Late Miocene clockwise rotations. Paleomagnetic data from older rocks do not give such clear regional patterns, as do the Late Miocene sites. However, both the Cretaceous Angat and the Eocene Zambales ophiolites appear to have originated at equatorial latitudes.