Deformation partitioning during folding and transposition of quartz layers.

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MetadadosDescriçãoIdioma
Autor(es): dc.creatorLagoeiro, Leonardo Evangelista-
Autor(es): dc.creatorHippertt, João-
Autor(es): dc.creatorLana, Cristiano de Carvalho-
Data de aceite: dc.date.accessioned2019-11-06T13:31:11Z-
Data de disponibilização: dc.date.available2019-11-06T13:31:11Z-
Data de envio: dc.date.issued2014-11-18-
Data de envio: dc.date.issued2014-11-18-
Data de envio: dc.date.issued2003-
Fonte completa do material: dc.identifierhttp://www.repositorio.ufop.br/handle/123456789/3953-
Fonte: dc.identifier.urihttp://educapes.capes.gov.br/handle/capes/557072-
Descrição: dc.descriptionBanded iron formation (BIF) from the Quadrilátero Ferrífero (southeastern Brazil) shows a compositional layering with alternating iron-rich and quartz-rich layers. This layering was intensively folded and transposed at a centimeter/millimeter scale through a component of bedding-parallel shear related to flexural slip at middle to high greenschist facies conditions (400–450 jC). The microstructure and c-axis fabrics of normal limbs, inverted limb and hinge zones of a selected isoclinal fold were analyzed combining optical and scanning electron microscopy (SEM) and digital image analysis. In the normal limbs, recrystallized quartz grains show undulose extinction, relatively dry grain boundaries, c-axes at high angle to foliation and a pervasive grain shape fabric (GSF) indicating operation of crystal-plastic processes. In the inverted limb, quartz grains show more serrated and porous (‘‘wet’’) grain boundaries; the GSF is similar to that of the normal limb, but c-axes are oriented at 90j to those of the normal limb. We interpreted these characteristics as reflecting operation of solution-precipitation deformation in inverted limbs, as a consequence of grains having been rotated to an orientation that was hard to basal hai glide, but easy to dissolution-precipitation creep. This deformation partitioning between crystal-plasticity and solution-transfer during folding/ transposition of quartz may explain the common occurrence of layered quartz rocks, where individual layers show alternating caxis fabrics with opposite asymmetries but a consistent GSF orientation. Such characteristics may reflect an earlier event of pervasive folding/transposition of a preexisting layering.-
Idioma: dc.languageen-
Direitos: dc.rightsO Periódico Tectonophysics concede permissão para depósito deste artigo no Repositório Institucional da UFOP. Número da licença: 3480320613550-
Palavras-chave: dc.subjectDeformation partitioning-
Palavras-chave: dc.subjectMicrostructures-
Palavras-chave: dc.subjectDissolution-precipitation creep-
Palavras-chave: dc.subjectCrystal-plasticity-
Palavras-chave: dc.subjectFoliation transposition-
Título: dc.titleDeformation partitioning during folding and transposition of quartz layers.-
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