This contribution presents a quantitative microstructural analysis of a polycrystalline aggregate of gypsum, deformed in torsion (T = 70-90 degrees C) at gamma (shear strain) ranging from 0 to 4.82. Quantitative microstructural analysis is used to compare the evolution of microstructures observed by optical microscope with those obtained from analysis of X-ray and neutron diffraction data. This analysis shows that during experimental deformation, gypsum accommodated strain by brittle and plastic deformation mechanisms, developing Riedel-like microfaults with plastic foliations and crystallographic preferred orientation (CPO). The relations of microstructures show that with increasing strain, the Riedel systems start from R planes with an angle of approximate to 30 degrees to the Imposed Shear Plane. This angle decreases (5 degrees-15 degrees) when strain increases, and Y planes develop. Quantitative texture analysis (QTA) shows that S-foliations start developing at low gamma and maintain their orientation up to high gamma, and that the most active slip system is the (010) along normal to (100) and the [001]-axis. Shape preferred orientation (SPO) of gypsum does not coincide with the theoretical orientation as it does not decrease with increasing strain. This discrepancy is explained by the role of the brittle shear planes that impose a back rotation to gypsum. No brittle to plastic transition occurs. But both plastic and brittle structures contemporaneously accommodate and localize strain.

Zucali, M., Barberini, V., Chateigner, D., Ouladdiaf, B., Lutterotti, L. (2010). Brittle plus plastic deformation of gypsum aggregates experimentally deformed in torsion to high strains: quantitative microstructural and texture analysis from optical and diffraction data. In M.I. Spalla, A.M. Marotta, G. Gosso (a cura di), Advances in Interpretation of Geological Processes: Refinement of Multi-scale Data and Integration in Numerical Modelling (pp. 79-98). Geological Society [10.1144/SP332.6].

Brittle plus plastic deformation of gypsum aggregates experimentally deformed in torsion to high strains: quantitative microstructural and texture analysis from optical and diffraction data

BARBERINI, VALENTINA;
2010

Abstract

This contribution presents a quantitative microstructural analysis of a polycrystalline aggregate of gypsum, deformed in torsion (T = 70-90 degrees C) at gamma (shear strain) ranging from 0 to 4.82. Quantitative microstructural analysis is used to compare the evolution of microstructures observed by optical microscope with those obtained from analysis of X-ray and neutron diffraction data. This analysis shows that during experimental deformation, gypsum accommodated strain by brittle and plastic deformation mechanisms, developing Riedel-like microfaults with plastic foliations and crystallographic preferred orientation (CPO). The relations of microstructures show that with increasing strain, the Riedel systems start from R planes with an angle of approximate to 30 degrees to the Imposed Shear Plane. This angle decreases (5 degrees-15 degrees) when strain increases, and Y planes develop. Quantitative texture analysis (QTA) shows that S-foliations start developing at low gamma and maintain their orientation up to high gamma, and that the most active slip system is the (010) along normal to (100) and the [001]-axis. Shape preferred orientation (SPO) of gypsum does not coincide with the theoretical orientation as it does not decrease with increasing strain. This discrepancy is explained by the role of the brittle shear planes that impose a back rotation to gypsum. No brittle to plastic transition occurs. But both plastic and brittle structures contemporaneously accommodate and localize strain.
Capitolo o saggio
gypsum, quantitative texture analysis, neutron diffraction, X-rays diffraction
English
Advances in Interpretation of Geological Processes: Refinement of Multi-scale Data and Integration in Numerical Modelling
Spalla, MI; Marotta, AM; Gosso, G
2010
978-1-86239-295-3
332
Geological Society
79
98
Zucali, M., Barberini, V., Chateigner, D., Ouladdiaf, B., Lutterotti, L. (2010). Brittle plus plastic deformation of gypsum aggregates experimentally deformed in torsion to high strains: quantitative microstructural and texture analysis from optical and diffraction data. In M.I. Spalla, A.M. Marotta, G. Gosso (a cura di), Advances in Interpretation of Geological Processes: Refinement of Multi-scale Data and Integration in Numerical Modelling (pp. 79-98). Geological Society [10.1144/SP332.6].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/10840
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