Glass microbeads in analog models of thrust wedges.
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2017
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Resumo
Glass microbeads are frequently used in analog physical modeling to simulate weak detachment zones but
have been neglected in models of thrust wedges. Microbeads differ from quartz sand in grain shape and
in low angle of internal friction. In this study, we compared the structural characteristics of microbeads
and sand wedges. To obtain a better picture of their mechanical behavior, we determined the physical and
frictional properties of microbeads using polarizing and scanning electron microscopy and ring-shear tests,
respectively. We built shortening experiments with different basal frictions and measured the thickness,
slope and length of the wedges and also the fault spacings. All the microbeads experiments revealed wedge
geometries that were consistent with previous studies that have been performed with sand. However, the
deformation features in the microbeads shortened over low to intermediate basal frictions were slightly
different. Microbeads produced different fault geometries than sand as well as a different grain flow. In
addition, they produced slip on minor faults, which was associated with distributed deformation and gave
the microbeads wedges the appearance of disharmonic folds. We concluded that the glass microbeads may
be used to simulate relatively competent rocks, like carbonates, which may be characterized by small-scale
deformation features.
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Compressional deformation models, Sand, Microbeads
Citação
D'ANGELO, T.; GOMES, C.; J.; S. Glass microbeads in analog models of thrust wedges. Anais da Academia Brasileira de Ciências, v. 89, p. 73-89, 2017. Disponível em: <http://www.scielo.br/scielo.php?script=sci_abstract&pid=S0001-37652017000100073&lng=pt&nrm=iso>. Acesso em: 25 ago. 2017.