Quantifying the contributions of Pacific Plate motion change and hotspot drift to the formation of Hawaiian-Emperor Bend

Abstract

<p>The Hawaiian-Emperor Seamount Chain changed its strike by 60° around 47 Ma, causing the Hawaiian-Emperor Bend (HEB). Both a change in Pacific Plate motion and a change in plume dynamics have been proposed to account for the HEB, but vigorous debates remain on their relative contribution. In order to have a better understanding, we build high–resolution global mantle convection models and test alternative plate reconstructions of North Pacific to quantify the contribution of each mechanism. For the contribution of Pacific Plate motion change, we find that Izanagi Plate subduction, followed by demise of the Izanagi–Pacific ridge and Izu–Bonin–Mariana subduction initiation alone, is incapable of causing a sudden change in plate motion, challenging the conventional hypothesis on the mechanisms of Pacific Plate motion change. Instead, with the alternative intra-oceanic subduction model, the Paleocene slab pull from Kronotsky subduction in North Pacific exerts a northward pull on the Pacific Plate, with its demise causing a sudden 30-35° change in plate motion. We further quantify the Hawaiian Hotspot drift using global mantle convection models with both the traditional and the alternative plate reconstructions. We find both models yield a fast southward drifting Hawaiian plume due to the push of slabs on the edge of the Pacific LLSVP. In the end, we discuss the combinational effects of Pacific Plate motion change and Hawaiian hotspot drift on the formation of HEB under different scenarios to gain insights on the possible history of North Pacific since the Late Cretaceous.</p>