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 hal.structure.identifier
BLACKMAN, D.K
121317 Scripps Institution of Oceanography [SIO]
dc.contributor.author
 hal.structure.identifier
BOYCE, D.E
99874 Cornell University
dc.contributor.author
 hal.structure.identifier
CASTELNAU, O
86289 Procédés et Ingénierie en Mécanique et Matériaux [Paris] [PIMM]
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DAWSON, P.R
99874 Cornell University
dc.contributor.author
 hal.structure.identifier
LASKE, G
121317 Scripps Institution of Oceanography [SIO]
dc.date.accessioned2018
dc.date.available2018
dc.date.issued2017
dc.date.submitted2017
dc.identifier.urihttp://hdl.handle.net/10985/12467
dc.description.abstractInsight into upper-mantle processes can be gained by linking flow-induced mineral alignment to regional deformation and seismic anisotropy patterns. Through a series of linked micro–macro scale numerical experiments, we explore the rheologic effects of crystal preferred orientation (CPO) and evaluate the magnitude of possible impacts on the pattern of flow and associated seismic signals for mantle that includes a cooling, thickening young oceanic lithosphere. The CPO and associated anisotropic rheology, computed by a micromechanical polycrystal model, are coupled with a large scale flow model (Eulerian Finite Element method) via a local viscosity tensor field, which quantifies the stress:strain rate response of a textured polycrystal. CPO is computed along streamlines throughout the model space and the corresponding viscosity tensor field at each element defines the local properties for the next iteration of the flow field. Stable flow and CPO distributions were obtained after several iterations for the two dislocation glide cases tested: linear and nonlinear stress:strain rate polycrystal behaviour. The textured olivine polycrystals are found to have anisotropic viscosity tensors in a significant portion of the model space. This directional dependence in strength impacts the pattern of upper-mantle flow. For background asthenosphere viscosity of ∼1020 Pa s and a rigid lithosphere, the modification of the corner flow pattern is not drastic but the change could have geologic implications. Feedback in the development of CPO occurs, particularly in the region immediately below the base of the lithosphere. Stronger fabric is predicted below the flanks of a spreading centre for fully coupled, power-law polycrystals than was determined using prior linear, intermediate coupling polycrystal models. The predicted SKS splitting is modestly different (∼0.5 s) between the intermediate and fully coupled cases for oceanic plates less than 20 Myr old. The magnitude of azimuthal anisotropy for surface waves, on the other hand, is predicted to be twice as large for fully coupled power-law flow/polycrystals than for linear, intermediate coupled flow/polycrystal models.
dc.language.isoen
dc.publisherAdvance Access publication
dc.rightsPost-print
dc.subjectMantle processes; Seismic anisotropy; Rheology: mantle.
dc.titleEffects of crystal preferred orientation on upper-mantle flow near plate boundaries: rheologic feedbacks and seismic anisotropy
ensam.embargo.terms2018-01-09
dc.identifier.doi10.1093/gji/ggx251
dc.typdocArticles dans des revues avec comité de lecture
dc.localisationCentre de Paris
dc.subject.halSciences de l'ingénieur: Matériaux
dc.subject.halSciences de l'ingénieur: Mécanique
ensam.audienceInternationale
ensam.page1481–1493
ensam.journalGeophysical Journal International
ensam.volume210
ensam.peerReviewingOui
hal.identifierhal-01676438
hal.version1
hal.submission.permittedupdateFiles


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