HAL will be down for maintenance from Friday, June 10 at 4pm through Monday, June 13 at 9am. More information
Skip to Main content Skip to Navigation
Journal articles

EBSD-measured lattice-preferred orientations and seismic properties of eclogites

Abstract : We investigated the deformation mechanisms and the seismic properties of 10 eclogite samples from different localities (Alps, Norway, Mali and eastern China) through the analysis of their microstructures and lattice-preferred orientations (LPO). These samples are representative of various types and intensity of deformation under eclogitic metamorphic conditions. Omphacite and garnet LPO were determined from electron backscatter diffraction (EBSD) technique. Garnet appears to be almost randomly oriented whereas omphacite develops strong LPO, characterized by the [001]-axes concentrated sub-parallel to the lineation, and the (010)-poles concentrated sub-perpendicular to the foliation. In order to analyze the deformation mechanisms that produced such omphacite LPO, we compare our observations to LPO simulated by viscoplastic self-consistent numerical models. A good fit to the measured LPO is obtained for models in which the dominant slip systems are 1/2h110i{11 ¯ 0}, [001] {110} and [001] (100). Dominant activation of these slip systems is in agreement with TEM studies of naturally deformed omphacite. Seismic properties of eclogite are calculated by combining the measured LPO and the single crystal elastic constants of omphacite and garnet. Although eclogite seismic anisotropies are very weak (less than 3% for both P-and S-wave), they are generally characterized by a maximum P-wave velocity sub-parallel to the lineation and by a minimum velocity approximately normal to foliation. The mean P-and S-wave velocities are high (respectively, 8.6 and 4.9 km/s). The S-wave anisotropy pattern displays complex relationships with the structural frame but the fast polarization plane generally tends to be parallel to the foliation. Calculated reflection coefficients show that an eclogite/crust interface is generally a good reflector (Rc > 0.1), whereas an eclogite body embedded in the upper mantle would be hardly detectable.
Document type :
Journal articles
Complete list of metadata

Cited literature [67 references]  Display  Hide  Download

Contributor : Guilhem Barruol Connect in order to contact the contributor
Submitted on : Saturday, October 29, 2016 - 8:28:52 AM
Last modification on : Wednesday, October 20, 2021 - 4:12:16 PM


Files produced by the author(s)



Jerôme Bascou, Guilhem Barruol, Alain Vauchez, David Mainprice, Marcos Egydio-Silva. EBSD-measured lattice-preferred orientations and seismic properties of eclogites. Tectonophysics, Elsevier, 2001, 342, pp.61 - 80. ⟨10.1016/S0040-1951(01)00156-1⟩. ⟨hal-01389715⟩



Record views


Files downloads