EGU21-10797, updated on 04 Mar 2021
https://doi.org/10.5194/egusphere-egu21-10797
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Similarities between the Madeira and Canary Hotspots Revealed by Seismic Anisotropy from Teleseismic and Local Shear-Wave Splitting with the SIGHT Project

David Schlaphorst1, Graça Silveira1,2, João Mata1, Frank Krüger3, Torsten Dahm3,4, and Ana Ferreira5
David Schlaphorst et al.
  • 1Universidade de Lisboa, Instituto Dom Luiz (IDL), Faculdade de Ciências, Lisboa, Portugal (dschlaphorst@fc.ul.pt)
  • 2Instituto Superior de Engenharia de Lisboa, Lisboa, Portugal
  • 3Universität Potsdam, Institut für Geowissenschaften, Potsdam, Germany
  • 4GFZ German Research Centre for Geosciences, Helmholtz Centre Potsdam, Potsdam, Germany
  • 5University College London, London, UK

The Madeira and Canary archipelagos, located in the eastern North Atlantic, are two of many examples of hotspot surface expressions, but a better understanding of the crust and upper mantle structure beneath these regions is needed to investigate their structure in more detail. With the study of seismic anisotropy, it is possible to assess the rheology and structure of asthenosphere and lithosphere that can reflect a combination of mantle and crustal contributions.

Here, as part of the SIGHT project (SeIsmic and Geochemical constraints on the Madeira HoTspot), we present the first detailed study of seismic anisotropy beneath both archipelagos, using data collected from over 60 local three-component seismic land stations. Basing our observations on both teleseismic SKS and local S splitting, we are able to distinguish between multiple layers of anisotropy. We observe significant changes in delay time and fast shear-wave orientation patterns on short length-scales on the order of tens of kilometres beneath the western Canary Islands and Madeira Island. In contrast, the eastern Canary Islands and Porto Santo the pattern is much more uniform. The detected delay time increase and more complex orientation patterns beneath the western Canary Islands and Madeira can be attributed to mantle flow disturbed and diverted on small-length scales by a strong vertical component. This is a clear indication of the existence of a plume at each of those archipelagos, nowadays exerting a strong influence on the western and younger islands. We therefore conclude that a plume-like feature beneath Madeira exists in a similar way to the Canary Island hotspot and that regional mantle flow models for the region should be reassessed.

This is a contribution to project SIGHT (Ref. PTDC/CTA-GEF/30264/2017). The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 – IDL.

How to cite: Schlaphorst, D., Silveira, G., Mata, J., Krüger, F., Dahm, T., and Ferreira, A.: Similarities between the Madeira and Canary Hotspots Revealed by Seismic Anisotropy from Teleseismic and Local Shear-Wave Splitting with the SIGHT Project, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10797, https://doi.org/10.5194/egusphere-egu21-10797, 2021.

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