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Journal Article

Toroidal flow around the Tonga slab moved the Samoan plume during the Pliocene

Authors

Konrad,  Kevin
External Organizations;

Jackson,  Matthew
External Organizations;

/persons/resource/bstein

Steinberger,  B.
2.5 Geodynamic Modelling, 2.0 Geophysics, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum;

Koppers,  Anthony
External Organizations;

Balbas,  Andrea
External Organizations;

Finlayson,  Valerie
External Organizations;

Konter,  Jasper
External Organizations;

Price,  Allison
External Organizations;

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5025896.pdf
(Postprint), 5MB

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Citation

Konrad, K., Jackson, M., Steinberger, B., Koppers, A., Balbas, A., Finlayson, V., Konter, J., Price, A. (2024): Toroidal flow around the Tonga slab moved the Samoan plume during the Pliocene. - Geology, 52, 3, 176-180.
https://doi.org/10.1130/G51588.1


Cite as: https://gfzpublic.gfz-potsdam.de/pubman/item/item_5025896
Abstract
Age-progressive seamount tracks generated by lithospheric motion over a stationary mantle plume have long been used to reconstruct absolute plate motion (APM) models. However, the basis of these models requires the plumes to move significantly slower than the overriding lithosphere. When a plume interacts with a convergent or divergent plate boundary, it is often deflected within the strong local mantle flow fields associated with such regimes. Here, we examined the age progression and geometry of the Samoa hotspot track, focusing on lava flow samples dredged from the deep flanks of seamounts in order to best reconstruct when a given seamount was overlying the mantle plume (i.e., during the shield-building stage). The Samoan seamounts display an apparent local plate velocity of 7.8 cm/yr from 0 to 9 Ma, 11.1 cm/yr from 9 to 14 Ma, and 5.6 cm/yr from 14 to 24 Ma. Current fixed and mobile hotspot Pacific APM models cannot reproduce the geometry of the Samoa seamount track if a long-term fixed hotspot location, currently beneath the active Vailulu’u Seamount, is assumed. Rather, reconstruction of the eruptive locations of the Samoan seamounts using APM models indicates that the surface expression of the plume migrated ~2° northward in the Pliocene. Large-scale mantle flow beneath the Pacific Ocean Basin cannot explain this plume migration. Instead, the best explanation is that toroidal flow fields—generated by westward migration of the Tonga Trench and associated slab rollback—have deflected the conduit northward over the past 2–3 m.y. These observations provide novel constraints on the ways in which plume-trench interactions can alter hotspot track geometries.