Ocean Island Basalts in Polynesia, South Pacific

Products of Magmatism Caused by Superplume Activity

Abstract

 Polynesia in the South Pacific is the location of a cluster of hotspots associated with a superswell. A large-scale seismic low-velocity anomaly found in the mantle beneath Polynesia indicates the existence of a superplume, which is responsible for the formation of the hotspot cluster and superswell. Basaltic lavas that erupted at volcanic islands in Polynesia are characterized by a large diversity of radiogenic isotopic ratios. The geochemical characteristics of Polynesian basalts are consistent with the involvement of subducted crustal material in the source mantle, suggesting that Polynesian basalts are products of the large-scale recycling of subducted crustal material facilitated by superplume activity.