Northward drift of the Azores plume in the Earth’s mantle

Maëlis Arnould (1) , Jérôme Ganne (2) , Nicolas Coltice (1) , Xiaojun Feng (3)

1 LGL-TPE - Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement
2 GET - Géosciences Environnement Toulouse
3 CUMT - China University of Mining and Technology

The fixity of mantle plumes has been a cornerstone assumption for the reconstruction of tectonic plate motions 1. However, paleomagnetic records and age progression along hotspot tracks have suggested substantial drift of plumes below the Pacific plate 2. Identifying the individual motion of a plume usually requires a long and continuous chain of seamounts, and precise geochronological and paleomagnetic data. Hence Hawaii is the only plume with clear evidence of drift so far 3,4. Here, we use plume-derived basalts from the Mid-Atlantic ridge (MAR) to map the mantle temperature over a large region in the upper mantle centered on the Azores. We show the thermal anomaly associated with the plume is asymmetric, spreading over ~2,000 km southwards and ~1,000 km northwards. The extent, shape and asymmetry of this anomaly cannot be accounted by a stationary plume. Using a 3D spherical mantle convection model allowing for self-consistent plate-like tectonics and drifting plumes, we show that the Azores plume moved northwards by 1-2 cm/yr from 85 Ma, independently from other Atlantic plumes, developing the Great-Meteor and Corner Rise volcanic chains.

Domaines: Sciences de la Terre

Maëlis Arnould, Jérôme Ganne, Nicolas Coltice, Xiaojun Feng. Northward drift of the Azores plume in the Earth’s mantle. Nature Communications, 2019, 10, pp.3235. ⟨10.1038/s41467-019-11127-7⟩. ⟨hal-03228578⟩