Plate Boundary and Triple Junction Control of Shatsky Rise Formation and Implications for Other Ocean Plateaus

Abstract In the study of marine large igneous provinces, investigations often focus on the importance of mantle plumes in generating excess magmatism. Few studies, however, have addressed the role of plate boundary processes in promoting widespread and extensive mantle melting. This study investigates how spreading center geometry may have facilitated the emplacement of Shatsky Rise, an oceanic plateau in the western Pacific Ocean. The largest structure within Shatsky Rise, Tamu Massif, was created ∼140–150 Ma at the Pacific‐Izanagi‐Farallon (PIF) ridge‐ridge‐ridge triple junction. Moreover, the PIF triple junction was one of three triple junctions operating in close proximity at the time, as the nascent Pacific Plate (NPP) began to expand in size. This study suggests that the thermal conditions of the NPP, which likely resulted in a large area of thin lithosphere, could have significantly facilitated widespread mantle melting as well as the magmatic expression of any nearby mantle plume.