Geochemical characteristics of amphiboles in gabbroic rocks of the Godzilla Megamullion, Parece Vela Basin, Philippine Sea

Abstract

The Godzilla Megamullion, the largest oceanic core complex, is located at the extinct Parece Vela Basin spreading ridge in the Philippine Sea. Fault rocks are common on the surface of the Godzilla Megamullion, indicating the presence of a detachment fault exposed on the seafloor (Harigane et al., 2011a). Based on a study of deformed gabbroic rocks at the breakaway region, Harigane et al. (2008) showed that the hydrothermal metamorphism occurred retrogressively, associated with deformation in the lower crust related to the detachment fault. But the origins of fluids and the fluid/rock ratio during deformation are still unsolved. Here, we present trace element geochemical analyses of amphibole and clinopyroxene of the gabbroic rocks sampled from the medial area of the Godzilla Megamullion.