Upper mantle–lower crust dikes of the Zambales Ophiolite Complex (Philippines): distinct short-lived, subduction-related magmatism

The residual harzburgite–lherzolite suites in the Coto and Acoje blocks of the Zambales Ophiolite Complex are cut by numerous dikes that range from clinopyroxenites to diabases, gabbros and diorites. Diabase dikes extensively cut the Coto block harzburgites while some clinopyroxenite to gabbro dikes are noted in the Acoje block lherzolite–harzburgite–dunite suite. The upper mantle–lower crust dikes in both blocks do not extend to their respective overlying sheeted dike–sill complexes. The whole-rock geochemistry of the mafic dikes intruded into the Coto and Acoje block peridotites show subduction-related signatures. These island-arc dikes are not unextracted frozen melts from their respective abyssal peridotite-like country rocks. They represent post-ophiolite, short-lived magmatic events that tapped geochemically different mantle source regions in a subduction-related marginal basin setting.