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dc.contributor.authorMansard, Nicolas
dc.contributor.authorStunitz, Holger
dc.contributor.authorRaimbourg, Hugues
dc.contributor.authorPrécigout, Jacques
dc.contributor.authorPlunder, Alexis
dc.contributor.authorNègre, Lucille
dc.date.accessioned2020-11-30T14:10:28Z
dc.date.available2020-11-30T14:10:28Z
dc.date.issued2020-11-18
dc.description.abstractSyn-kinematic mineral reactions play an important role for the mechanical properties of polymineralic rocks. Mineral reactions (i.e., nucleation of new phases) may lead to grain size reduction, producing fine-grained polymineralic mixtures, which have a strongly reduced viscosity because of the activation of grain-size-sensitive deformation processes. In order to study the effect of deformation–reaction feedback(s) on sample strength, we performed rock deformation experiments on “wet” assemblages of mafic compositions in a Griggs-type solid-medium deformation apparatus. Shear strain was applied at constant strain rate (10−5 s−1) and constant confining pressure (1 GPa) with temperatures ranging from 800 to 900 ∘C. At low shear strain, the assemblages that react faster are significantly weaker than the ones that react more slowly, demonstrating that reaction progress has a first-order control on rock strength. With increasing strain, we document two contrasting microstructural scenarios: (1) the development of a single throughgoing high-strain zone of well-mixed, fine-grained aggregates, associated with a significant weakening after peak stress, and (2) the development of partially connected, nearly monomineralic shear bands without major weakening. The lack of weakening is caused by the absence of interconnected well-mixed aggregates of fine-grained reaction products. The nature of the reaction products, and hence the intensity of the mechanical weakening, is controlled by the microstructures of the reaction products to a large extent, e.g., the amount of amphibole and the phase distribution of reaction products. The samples with the largest amount of amphibole exhibit a larger grain size and show less weakening. In addition to their implications for the deformation of natural shear zones, our findings demonstrate that the feedback between deformation and mineral reactions can lead to large differences in mechanical strength, even at relatively small initial differences in mineral composition.en_US
dc.identifier.citationMansard N, Stunitz H, Raimbourg H, Précigout J, Plunder A, Nègre. Relationship between microstructures and resistance in mafic assemblages that deform and transform. Solid Earth (SE). 2020;11:2141-2020en_US
dc.identifier.cristinIDFRIDAID 1850402
dc.identifier.doi10.5194/se-11-2141-2020
dc.identifier.issn1869-9510
dc.identifier.issn1869-9529
dc.identifier.urihttps://hdl.handle.net/10037/19942
dc.language.isoengen_US
dc.publisherEuropean Geosciences Union (EGU)en_US
dc.relation.journalSolid Earth (SE)
dc.relation.projectIDAndre: Labex VOLTAIRE (ANR-10-LABX-100-01)en_US
dc.relation.projectIDAndre: CNRS INSU (SYSTER)en_US
dc.relation.projectIDEC/FP7: 290864en_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2020 The Author(s)en_US
dc.subjectVDP::Mathematics and natural science: 400::Geosciences: 450en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Geofag: 450en_US
dc.titleRelationship between microstructures and resistance in mafic assemblages that deform and transformen_US
dc.type.versionpublishedVersionen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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