On the relative motions of long-lived Pacific mantle plumes

Kevin Konrad,Valerie A Finlayson,Matthew G Jackson,Bernhard Steinberger,Anthony A P Koppers,Jasper G Konter

doi:10.1038/s41467-018-03277-x

Abstract

Mantle plumes upwelling beneath moving tectonic plates generate age-progressive chains of volcanos (hotspot chains) used to reconstruct plate motion. However, these hotspots appear to move relative to each other, implying that plumes are not laterally fixed. The lack of age constraints on long-lived, coeval hotspot chains hinders attempts to reconstruct plate motion and quantify relative plume motions. Here we provide 40Ar/39Ar ages for a newly identified long-lived mantle plume, which formed the Rurutu hotspot chain. By comparing the inter-hotspot distances between three Pacific hotspots, we show that Hawaii is unique in its strong, rapid southward motion from 60 to 50 Myrs ago, consistent with paleomagnetic observations. Conversely, the Rurutu and Louisville chains show little motion. Current geodynamic plume motion models can reproduce the first-order motions for these plumes, but only when each plume is rooted in the lowermost mantle.

Highlights

Mantle plumes upwelling beneath moving tectonic plates generate age-progressive chains of volcanos used to reconstruct plate motion
Focused subduction along the Aleutian arc between 100 and 50 Ma may have caused a strong southward deep mantle flow that has affected the Pacific large low shear velocity province (LLSVP)[9] and the starting locations of plumes, assuming that plumes initiate from the LLSVP edges[10]
We find that modeled motions can reproduce first-order trends only if plumes are rooted, but not anchored, near the core-mantle boundary (CMB)

Summary

Introduction

Mantle plumes upwelling beneath moving tectonic plates generate age-progressive chains of volcanos (hotspot chains) used to reconstruct plate motion. The new 40Ar/39Ar age determinations presented here link the Tuvalu seamount chain to the Rurutu hotspot, allowing us to define the motion of the Rurutu plume relative to the previously dated, long-lived Louisville and Hawaiian hotspots.

Results

Conclusion