The principal investigator will map, sample, and make a mineralogic-petrologic-geochemical-isotopic study of selected plutonic and volcanic rocks in north Luzon, Philippines. The purpose is to determine the chemical and isotopic compositions of four distinct increments of crustal rocks that have led to the progressive transformation from basaltic island arc crust to more highly evolved crust. The investigation will address the question of whether the Luzon arc systems formed largely from melts of the mantle wedge above subduction zones, followed by modification via assimilation zone-refining of the arc crust, plus fractional crystallization, resulting later in the production of more granitic compositions. This area offers a unique opportunity for geologists to trace the early stages of crustal evolution of a microcontinent.
