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Deformation, CPO, and Elastic Anisotropy in Low‐Grade Metamorphic Serpentinites, Atlantis Massif Oceanic Core Complex
Author(s) -
Kuehn R.,
Behrmann J. H.,
Stipp M.,
Kilian R.,
Leiss B.
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl092986
Subject(s) - geology , massif , seismic anisotropy , anisotropy , mantle (geology) , metamorphic rock , shear zone , shear (geology) , mineralogy , geophysics , seismology , petrology , tectonics , geochemistry , physics , quantum mechanics
Crystallographic preferred orientation (CPO) and the associated seismic anisotropy of serpentinites are important factors for the understanding of tectonic settings involving hydrated Earth´s mantle, for example, at slow‐spreading mid‐ocean ridges. CPO of lizardite and magnetite in low‐grade metamorphic serpentinites from the Atlantis Massif oceanic core complex (Mid‐Atlantic Ridge, 30°N) were determined using synchrotron high energy X‐ray diffraction in combination with Rietveld texture analysis. Serpentinite mesh structures show weak CPO while deformed samples show a single (0001) maximum perpendicular to the foliation. Seismic anisotropies calculated from CPO show up to >11% anisotropy for compressional waves ( Vp ) and shear wave splitting up to 0.38 km/s in the deformed samples. This indicates that deformation in shear zones controls elastic anisotropy and highlights its importance in defining the seismic signature of hydrated upper mantle.