Pore morphology and distribution in the Shaly facies of Opalinus Clay (Mont Terri, Switzerland): Insights from representative 2D BIB–SEM investigations on mm to nm scale

Houben, M.E.; Desbois, Guillaume; Urai, János L.

doi:10.1016/j.clay.2012.11.006

Cited by 178 publications

(159 citation statements)

References 37 publications

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“…5 and 6) were imaged with a Supra 55-Zeiss SEM (SE2 and BSE detectors at 20 kV and working distance (WD) = 8 mm). Further details of the method are given in Klaver et al, 2012Klaver et al, , 2015Houben et al, 2013Houben et al, , 2014Hemes et al, 2013Hemes et al, , 2015and Desbois et al, 2016.…”

Section: Methods: Bib-sem Imaging Of Deformed Microstructuresmentioning

confidence: 99%

“…FIB and BIB), which allow imaging of mineral fabrics and porosity down to the nanometre scale in very high-quality cross sections with SEM and TEM (Lee et al, 2003;Desbois et al, 2009Desbois et al, , 2011Desbois et al, , 2013Desbois et al, , 2016Loucks et al, 2009;Curtis et al, 2010;Heath et al, 2011;Klaver et al, 2012;Keller et al, 2011Keller et al, , 2013Houben et al, 2013Houben et al, , 2014Hemes et al, 2013Hemes et al, , 2015Laurich et al, 2014;Warr et al, 2014;Song et al, 2016). Serial sectioning allows the reconstruction of microstructure in 3-D (Keller et al, 2011(Keller et al, , 2013Milliken et al, 2013;Hemes et al, 2015), and cryogenic techniques can image the pore fluid in the samples and avoid artefacts produced by drying Schmatz et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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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

Desbois¹,

Höhne²,

Urai³

et al. 2017

Solid Earth

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Abstract. 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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Section: Methods: Bib-sem Imaging Of Deformed Microstructuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Desbois¹,

Höhne²,

Urai³

et al. 2017

Solid Earth

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“…parallel to the bedding planes) leading to swelling in normal direction. Moreover, according to Houben et al (2013), the pores of Opalinus Clay are elongated along the bedding.…”

Section: Strain and Damagementioning

confidence: 99%

The response of Opalinus Clay when exposed to cyclic relative humidity variations

2017

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Abstract. Clay shale specimens were exposed to cyclic relative humidity (RH) variations to investigate the response of the material to natural environmental changes. Opalinus Clay, a clay shale chosen as host rock for nuclear waste disposal in Switzerland, was utilized. The specimens were exposed to stepwise relative humidity cycles in which they were alternately allowed to equilibrate at 66 and 93 % relative humidity. Principal strains were monitored throughout the experiments using strain gauges. After each relative humidity cycle, Brazilian tensile strength tests were performed to identify possible changes in tensile strength due to environmental degradation.Results showed that Opalinus Clay follows a cyclic swelling-shrinkage behaviour with irreversible expansion limited to the direction normal to bedding, suggesting that internal damage is restricted along the bedding planes. The Brazilian tensile strength in direction parallel and normal to bedding as well as the water retention characteristic remained unaffected by the RH variations.

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“…However observations of septarian veining in phosphate nodules attested to compaction processes. The low diagenesis process intensity resulted in larger pore diameters and porosity (28 ± 3%) in comparison to clay-rock strongly influenced by chemical compaction, such as the Callovo-Oxfordian or Opalinus clay formations for instance [57][58][59]. Unweathered Tégulines Clay consisted of more than 75% of detrital minerals including quartz, K-feldspar, kaolinite, chlorite, illitesmectite and chlorite-smectite mixed layers, detrital calcite and phosphate bioclasts, and infratraces of goethite and magnetite.…”

Section: Oxidation Profilementioning

confidence: 99%

A Deep Alteration and Oxidation Profile in a Shallow Clay Aquitard: Example of the Tégulines Clay, East Paris Basin, France

Lerouge

Robinet²,

Debure

et al. 2018

Geofluids

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The oxidation profile of a surficial clay aquitard was studied on a 35-meter borecore from the Albian Tégulines Clay near Brienne-leChâteau (Paris Basin, France). Mineralogical, geochemical, and petrophysical data showed evidences of gradual oxidation taking place down to a depth of 20 m. Below 20 m, the clay material was nonplastic and nonfractured, and it inherited reduced redox conditions from bacterial sulfate reduction that occurred after sediment deposition. Above 20 m, the clay material was plastic. Up to a depth of 10-11 m, only rare yellowish aggregates of glauconite attested to limited oxidation, and pore water chemistry was unmodified. The 5-11 m depth interval was characterized by intensive pyrite oxidation, calcite dissolution, and formation of sulfate and iron hydroxide minerals. The upper 2-3 m was ochrous and entirely oxidized. These mineralogical changes were mirrored with pore water chemistry modifications such as an increase of alkalinity and sulfate concentration in the upper part of the profile. The presence of siderite at ∼11 m evinced the reactivity of Fe(II) in the structure of clay minerals with dioxygen from meteoric waters that infiltrated into the Tégulines Clay through vertical fractures.

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Pore morphology and distribution in the Shaly facies of Opalinus Clay (Mont Terri, Switzerland): Insights from representative 2D BIB–SEM investigations on mm to nm scale

Cited by 178 publications

References 37 publications

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

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 response of Opalinus Clay when exposed to cyclic relative humidity variations

A Deep Alteration and Oxidation Profile in a Shallow Clay Aquitard: Example of the Tégulines Clay, East Paris Basin, France

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