Mantle Plumes pp 439-464

Seismic Anisotropy in the Asthenosphere Beneath the Eifel Region, Western Germany

  • Kristoffer T. Walker
  • Götz H. R. Bokelmann
  • Simon L. Klemperer
  • Günter Bock
  • The Eifel Plume Team

Abstract

We provide evidence for a plume-like upwelling beneath the Eifel hotspot, Western Germany, by using teleseismic shear-wave splitting to resolve the anisotropy associated with upwelling flow that is spreading laterally into the asthenosphere. The variation in fast-polarization azimuth we find across the Eifel hotspot is explained by a model of slowly upwelling material that is horizontally being deflected or sheared in a parabolic asthenospheric flow (PAF) pattern toward west-southwest, a direction that correlates with Eurasian absolute plate motion. We suggest that the lack of an age progression for Eifel volcanism, which is expected for a fixed-upwelling model, is a result of (1) sporadic volcanism due to a low excess plume temperature and/or varying crustal stresses that periodically relax and facilitate eruption, and (2) complex upwelling flow pathways and/or Late Tertiary changes in the slow Eurasian plate motion. The success of the PAF model in fitting the data is remarkable given the small number of parameters (four) and the consistency with the plate motion direction determined from geology and/or geodesy. This suggests that a predictable mantle-anisotropy pattern may exist also for other hotspots driven by plume-like upwellings, and that splitting can be a useful diagnostic to differentiate between plume-like and alternative sources for mantle hotspots.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2007

Authors and Affiliations

  • Kristoffer T. Walker
    • 1
  • Götz H. R. Bokelmann
    • 2
  • Simon L. Klemperer
    • 3
  • Günter Bock
    • 4
  • The Eifel Plume Team
  1. 1.Institute of Geophysics and Planetary Physics, Scripps Institution of OceanographyUniversity of CaliforniaSan Diego
  2. 2.Laboratoire de TectonophysiqueUniversité Montpellier IIMontpellierFrance
  3. 3.Department of GeophysicsStanford UniversityStanford
  4. 4.GeoForschungsZentrum PotsdamPotsdam

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