Deformation in cemented mudrock (Callovo–Oxfordian Clay) by microcracking, granular flow and phyllosilicate plasticity: insights from triaxial deformation, broad ion beam polishing and scanning electron microscopy
The macroscopic description of deformation and fluid flow in mudrocks can be improved by a better understanding of microphysical deformation mechanisms. Here we use a combination of scanning electron microscopy (SEM) and broad ion beam (BIB) polishing to study the evolution of microstructure in samp...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-03-01
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| Series: | Solid Earth |
| Online Access: | http://www.solid-earth.net/8/291/2017/se-8-291-2017.pdf |
| Summary: | The macroscopic description of deformation and fluid flow in mudrocks can be
improved by a better understanding of microphysical deformation mechanisms.
Here we use a combination of scanning electron microscopy (SEM) and broad
ion beam (BIB) polishing to study the evolution of microstructure in samples
of triaxially deformed Callovo–Oxfordian Clay. Digital image correlation
(DIC) was used to measure strain field in the samples and as a guide to
select regions of interest in the sample for BIB–SEM analysis.
Microstructures show evidence for dominantly cataclastic and minor crystal
plastic mechanisms (intergranular, transgranular, intragranular cracking,
grain rotation, clay particle bending) down to the nanometre scale. At low strain, the
dilatant fabric contains individually recognisable open fractures, while at
high strain the reworked clay gouge also contains broken non-clay grains and
smaller pores than the undeformed material, resealing the initial fracture
porosity. |
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| ISSN: | 1869-9510 1869-9529 |