Author's Personal Copy
Author's personal copy Tectonophysics 494 (2010) 201–210 Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto Elasticity of glaucophane, seismic velocities and anisotropy of the subducted oceanic crust L. Bezacier a,⁎, B. Reynard a, J.D. Bass b, J. Wang b, D. Mainprice c a Université de Lyon, Laboratoire de Sciences de la Terre, CNRS, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France b Department of Geology, University of Illinois, Urbana, IL, 61801, USA c Géosciences Montpellier UMR CNRS 5343, Université Montpellier 2, 34095 Montpellier Cedex 05, France article info abstract Article history: Upon subduction, the oceanic crust transforms to blueschists and eclogites, with seismic properties that Received 8 March 2010 gradually become similar to those of the surrounding mantle. In order to evaluate the anisotropy of Received in revised form 30 July 2010 blueschists and glaucophane-bearing eclogites, the elastic constants of glaucophane single-crystal plates from Accepted 9 September 2010 the Sesia–Lanzo Zone (Aosta Valley, Western Alps) were measured using Brillouin spectroscopy at ambient Available online 17 September 2010 conditions. The mean P- and S-wave velocities are 7.8 and 4.6 km s−1 respectively, and the anisotropy is high Keywords: (38.1% (AVP) and 27.3% (AVS)). Glaucophane develops strong LPO, characterized by the [001]-axes Elasticity concentrated sub-parallel to the lineation, and the {110} poles concentrated sub-perpendicular to the Glaucophane foliation in both blueschist and eclogite rocks. The measured LPO is in good agreement with viscoplastic self- Epidote consistent numerical models.
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