Thermal Nature of Mantle Upwellings Below the Ibero‐Western Maghreb Region Inferred From Teleseismic Tomography

Civiero, Chiara and Custódio, Susana and Rawlinson, Nicholas and Strak, Vincent and Silveira, Graça and Arroucau, Pierre and Corela, Carlos (2019) Thermal Nature of Mantle Upwellings Below the Ibero‐Western Maghreb Region Inferred From Teleseismic Tomography. Journal of Geophysical Research: Solid Earth, 124 (2). pp. 1781-1801. ISSN 2169-9313 DOI https://doi.org/10.1029/2018JB016531

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Abstract

Independent models of P wave and S wave velocity anomalies in the mantle derived from seismic tomography help to distinguish thermal signatures from those of partial melt, volatiles, and compositional variations. Here we use seismic data from SW Europe and NW Africa, spanning the region between the Pyrenees and the Canaries, in order to obtain a new S‐SKS relative arrival‐time tomographic model of the upper mantle below Iberia, Western Morocco, and the Canaries. Similar to previous P wave tomographic results, the S wave model provides evidence for (1) subvertical upper‐mantle low‐velocity structures below the Canaries, Atlas Ranges, and Gibraltar Arc, which are interpreted as mantle upwellings fed by a common lower‐mantle source below the Canaries; and (2) two low‐velocity anomalies below the eastern Rif and Betics that we interpret as the result of the interaction between quasi‐toroidal mantle flow induced by the Gibraltar slab and the mantle upwelling behind it. The analysis of teleseismic P wave and S wave arrival‐time residuals and the conversion of the low‐velocity anomalies to temperature variations suggest that the upwellings in the upper mantle below the Canaries, Atlas Ranges, and Gibraltar Arc system may be solely thermal in nature, with temperature excesses in the range ~100–350 °C. Our results also indicate that local partial melting can be present at lithospheric depths, especially below the Atlas Ranges. The locations of thermal mantle upwellings are in good agreement with those of thinned lithosphere, moderate to high heat‐flow measurements, and recent magmatic activity at the surface.

Item Type: Article
Uncontrolled Keywords: 2018AREP, IA74
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
08 - Green Open Access
Journal or Publication Title: Journal of Geophysical Research: Solid Earth
Volume: 124
Page Range: pp. 1781-1801
Identification Number: https://doi.org/10.1029/2018JB016531
Depositing User: Sarah Humbert
Date Deposited: 11 Apr 2019 17:35
Last Modified: 12 Sep 2019 09:41
URI: http://eprints.esc.cam.ac.uk/id/eprint/4477

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