The Canary Islands hot spot: New insights from 3D coupled geophysical–petrological modelling of the lithosphere and uppermost mantle

Abstract

The Canary archipelago (NW Atlantic African margin) is one of the best studied volcanic chains in the world yet its structure and geodynamic evolution are still under considerable debate. Oceanic island volcanoes typically form over hot spots due to upwelling of plume material followed by decompression melting and melt migration up to the surface. Here, the 3D lithospheric-uppermost mantle thermochemical structure beneath the Canary Islands is studied using an integrated and self-consistent geophysical-petrological approach exploiting the wealth of available data after decades of geophysical and petrological studies plus recent satellite data. A precise knowledge of the present-day thermal and compositional mantle structure beneath the Canary Islands is a key element to understand the geodynamic evolution of the area and, on a global scale, the thermal state of the Earth's mantle beneath hot spots. Our results suggest a likely chemically depleted and mechanically strong lithosphere showing no significant thinning with respect to the surrounding oceanic and continental domains (110 +/- 20 km thick). Models without a positive temperature anomaly in the sub-lithosphere (characterized by mantle T-pot = 1335 degrees C) fail to reproduce the observed sub-lithospheric seismic anomaly over the Canary Islands. A thermal sub-lithospheric anomaly of +100 degrees C (mantle potential temperature of 1435 degrees C) with respect to ambient mantle beneath the Canaries is able to explain both observed seismic tomography anomalies and measured geophysical and geodetic data. Such a sub-lithospheric thermal anomaly requires a dynamic contribution of 150-400 m to the static topography to match the present-day observed elevation in the Canary Islands and associated swell.