An emerging plume head interacting with the Hawaiian plume tail

The Hawaiian-Emperor seamount chain has shown two subparallel geographical and geochemical volcanic trends, Loa and Kea, since -5 Ma, for which numerous models have been proposed that usually involve a single mantle plume sampling different compositional sources of the deep or shallow mantle. However, both the dramatically increased erup-tion rate of the Hawaiian hotspot since -5 Ma and the nearly simulta-neous southward bending of the Hawaiian chain remain unexplained. Here, we propose a plume-plume interaction model where the composi-tionally depleted Kea trend represents the original Hawaiian plume tail and the relatively enriched Loa trend represents an emerging plume head southeast of the Hawaiian plume tail. Geodynamic modeling further suggests that the interaction between the existing Hawaiian plume tail and the emerging Loa plume head is responsible for the southward bending of the Hawaiian chain. We show that the arrival of the new plume head also dramatically increases the eruption rate along the hot-spot track. We suggest that this double-plume scenario may also repre-sent an important mechanism for the formation of other hotspot tracks in the Pacific plate, likely reflecting a dynamic reorganization of the lowermost mantle.

Automated summary

The Hawaiian-Emperor seamount chain displays two parallel volcanic trends, Loa and Kea, which have been studied extensively. However, the increased eruption rate and southward bending of the chain remain unexplained. This study proposes a plume-plume interaction model, where the Loa trend represents an emerging plume head southeast of the original Hawaiian plume tail, and the interaction between these two plumes is responsible for the southward bending and increased eruption rate. This double-plume scenario may also play a role in the formation of other hotspot tracks.