Northward motion of the Azores mantle plume over the last 85 Ma
Abstract
Although many plate reconstructions have used the assumption that mantle plumes are stationary in Earth's mantle (e.g. Müller et al., 1993), several paleomagnetic and geochronological studies along long and continuous hotspot tracks have suggested a substantial drift of the Hawaiian and the Louisville plumes below the Pacific plate (Konrad et al., 2018, Koppers et al., 2004, Tarduno et al., 2003).
Here, we use plume-derived basalts sampled along the Mid-Atlantic ridge (MAR) in the Azores area in order to map the upper mantle thermal anomaly below the ridge. The thermal anomaly corresponding to the plume wake is asymmetric, spreading over 2,000 km southwards and 1,000 km northwards, and coincides with an asymmetric anomaly of topography and upper-mantle seismic velocity along the MAR. The shape, extent and asymmetry of the anomaly cannot result from a fixed plume. We use a 3D spherical mantle convection model self-generating plate-like tectonics and drifting plumes in order to show that the Azores plume moved northwards by 1-2 cm/yr from 85 Ma, independently from other Atlantic plumes, and participated to the formation of the Great-Meteor and Corner Rise volcanic chains. References: Konrad, K., Koppers, A.A., Steinberger, B., Finlayson, V.A., Konter, J.G., Jackson, M.G., 2018. On the relative motions of long-lived pacfiic mantle plumes. Nature communications 9, 854. Koppers, A.A., Duncan, R.A., Steinberger, B., 2004. Implications of a nonlinear 40Ar/39Ar age progression along the Louisville seamount trail for models of fixed and moving hot spots. Geochemistry, Geophysics,Geosystems 5. Müller, R.D., Royer, J.Y., Lawver, L.A., 1993. Revised plate motions relative to the hotspots from combined Atlantic and Indian ocean hotspot tracks. Geology 21, 275-278. Tarduno, J.A., Duncan, R.A., Scholl, D.W., Cottrell, R.D., Steinberger, B., Thordarson, T., Kerr, B.C., Neal, C.R., Frey, F.A., Torii, M., et al., 2003. The Emperor seamounts: Southward motion of the hawaiian hotspot plume in earth's mantle. Science 301, 1064-1069.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.T43A..06A
- Keywords:
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- 1038 Mantle processes;
- GEOCHEMISTRYDE: 1115 Radioisotope geochronology;
- GEOCHRONOLOGYDE: 8137 Hotspots;
- large igneous provinces;
- and flood basalt volcanism;
- TECTONOPHYSICSDE: 8450 Planetary volcanism;
- VOLCANOLOGY