Microstructural evolution of an incipient fault zone in Opalinus Clay: Insights from an optical and electron microscopic study of ion-beam polished samples from the Main Fault in the Mt-Terri Underground Research Laboratory

2014 ◽  
Vol 67 ◽  
pp. 107-128 ◽  
Author(s):  
Ben Laurich ◽  
Janos L. Urai ◽  
Guillaume Desbois ◽  
Christian Vollmer ◽  
Christophe Nussbaum
Keyword(s):  
Microscopic Study ◽  
Fault Zone ◽  
Microstructural Evolution ◽  
Research Laboratory ◽  
Ion Beam ◽  
Opalinus Clay ◽  
Electron Microscopic ◽  
Main Fault ◽  
Incipient Fault ◽  
Underground Research Laboratory

scholarly journals Impact of the heterogeneity of the sandy Opalinus clay facies at the Mont Terri underground research laboratory on radionuclide migration

2021 ◽  
Vol 1 ◽  
pp. 141-142
Author(s):  
Naila Ait-Mouheb ◽  
Yuankai Yang ◽  
Luc R. Van Loon ◽  
Martin A. Glaus ◽  
Guido Deissmann ◽  
...  
Keyword(s):  
Research Laboratory ◽  
Radioactive Wastes ◽  
Coupled Processes ◽  
Opalinus Clay ◽  
Nuclear Waste Repository ◽  
Radionuclide Transport ◽  
Mont Terri ◽  
Underground Research Laboratory ◽  
Host Rocks ◽  
The Impact

Abstract. The assessment of the safety of a deep geological repository (DGR) for high-level radioactive wastes over assessment time scales of up to 1 million years requires an in-depth understanding of the multi-scale coupled processes that affect the repository system evolution over time, to reduce uncertainties and conservatism in safety analyses. This is in particular required with respect to the challenges of a comparative assessment of different repository concepts in different host rocks within the process of a site selection for a DGR for heat-generating radioactive wastes in Germany. The collaborative project “Integrity of nuclear waste repository systems – Cross-scale system understanding and analysis (iCross)” conducted jointly by five research centres of the Helmholtz Association and co-funded by the Initiative and Networking Fund of the Helmholtz Association and the Federal Ministry of Education and Research (BMBF) has been initiated with the overall objective to improve the understanding of coupled thermal-hydraulic-mechanical-chemical-(micro)biological (THMCB) processes and to develop simulation tools that enable a holistic close to reality description of the long-term evolution of the repository system. Geological formations, such as those foreseen as potential host rocks for DGRs, and their surroundings are heterogeneous on various length scales ranging from nanometers to kilometers. Therefore, the aim of this work in the context of iCross is to evaluate the effects of mineralogical, geochemical and microstructural heterogeneities of repository host rocks on radionuclide transport in the repository far field, using the sandy facies of the Opalinus clay (SF-OPA) from the Mont Terri underground research laboratory (St. Ursanne, Switzerland) as an example. Here, we address in particular the migration behaviour of Ra-226 as an important radionuclide to be considered in safety cases for deep geological disposal of spent nuclear fuel. To assess the impact of the heterogeneities in SF-OPA on radionuclide transport, a complementary approach combining microstructural characterisation methods, experimental techniques for the determination of transport parameters of the rock matrix and the mobility of Ra-226 with innovative developments in reactive transport modelling on the pore and continuum scales was pursued. One of the results was that although the limited clay content in SF-OPA decreases the total amount of Ra bound to the illite phase, the solid solutions of sulphate and carbonate compensate for this and provide a major fixation mechanism.

scholarly journals Microstructures and deformation mechanisms in Opalinus Clay: insights from scaly clay from the Main Fault in the Mont Terri Rock Laboratory (CH)

2016 ◽  
Author(s):  
Ben Laurich ◽  
Janos L. Urai ◽  
Christophe Nussbaum
Keyword(s):  
Ion Beam ◽  
Shear Zones ◽  
Deformation Mechanisms ◽  
Opalinus Clay ◽  
Reverse Fault ◽  
Pore Collapse ◽  
Power Law Distribution ◽  
Calcite Veins ◽  
Main Fault ◽  
Scaly Clay

Abstract. The Main Fault in the shaly facies of Opalinus Clay is a small reverse fault formed in slightly overconsolidated claystone at around one km depth. The fault zone is up to 6 m wide, with micron-thick shear zones, calcite and celestite veins, scaly clay and clay gouge. Scaly clay occurs in up to 1.5 m wide lenses, providing hand specimens for this study. After mapping of the macroscopic fabric at 10 cm–0.1 mm scale, Broad Ion Beam polishing combined with scanning electron microscopy (BIB-SEM) was used to study microscale deformation mechanisms. Results show a network of thin shear zones and microveins, separating angular to lensoid microlithons between 3 cm and 10 µm in diameter, with slickensided surfaces. Samples can be easily disintegrated into individual microlithons because of the very low tensile strength of the thin shear zones. Analyses of the size of microlithons show a power law distribution. We present a model to explain the progressive formation of a self-similar network of anastomosing thin shear zones during macroscopically continuous deformation in a fault relay. Localisation of strain in thin shear zones which are locally dilatant, and precipitation of calcite veins in dilatant shear fractures evolves into complex re-partitioning of shear, forming new shear zones at asperities while the microlithons remain much less deformed internally and the volume proportion of the µm-thick shear zones slowly increases. Grain scale deformation mechanisms are: microfracturing, boudinage and rotation of mica grains, pressure solution of carbonate fossils and pore collapse during ductile flow of the clay matrix. This provides a microphysical basis to relate the microstructures to macroscopic observations of strength and permeability of the Main Fault, and extrapolating fault properties in long term deformation.

scholarly journals Microstructures and deformation mechanisms in Opalinus Clay: insights from scaly clay from the Main Fault in the Mont Terri Rock Laboratory (CH)

Solid Earth ◽  
2017 ◽  
Vol 8 (1) ◽  
pp. 27-44 ◽  
Author(s):  
Ben Laurich ◽  
Janos L. Urai ◽  
Christophe Nussbaum
Keyword(s):  
Ion Beam ◽  
Shear Zones ◽  
Deformation Mechanisms ◽  
Opalinus Clay ◽  
Distribution Model ◽  
Reverse Fault ◽  
Deformation Localization ◽  
Calcite Veins ◽  
Main Fault ◽  
Scaly Clay

Abstract. The Main Fault in the shaly facies of Opalinus Clay is a small reverse fault formed in slightly overconsolidated claystone at around 1 km depth. The fault zone is up to 6 m wide, with micron-thick shear zones, calcite and celestite veins, scaly clay and clay gouge. Scaly clay occurs in up to 1.5 m wide lenses, providing hand specimens for this study. We mapped the scaly clay fabric at 1 m–10 nm scale, examining scaly clay for the first time using broad-ion beam polishing combined with scanning electron microscopy (BIB-SEM). Results show a network of thin shear zones and microveins, separating angular to lensoid microlithons between 10 cm and 10 µm in diameter, with slickensided surfaces. Our results show that microlithons are only weakly deformed and that strain is accumulated by fragmentation of microlithons by newly formed shear zones, by shearing in the micron-thick zones and by rearrangement of the microlithons.The scaly clay aggregates can be easily disintegrated into individual microlithons because of the very low tensile strength of the thin shear zones. Analyses of the microlithon size by sieving indicate a power-law distribution model with exponents just above 2. From this, we estimate that only 1 vol % of the scaly clay aggregate is in the shear zones.After a literature review of the hypotheses for scaly clay generation, we present a new model to explain the progressive formation of a self-similar network of anastomosing thin shear zones in a fault relay. The relay provides the necessary boundary conditions for macroscopically continuous deformation. Localization of strain in thin shear zones which are locally dilatant, and precipitation of calcite veins in dilatant shear fractures, evolve into complex microscale re-partitioning of shear, forming new shear zones while the microlithons remain much less deformed internally and the volume proportion of the µm-thick shear zones slowly increases. Grain-scale deformation mechanisms are microfracturing, boudinage and rotation of mica grains, pressure solution of carbonate fossils and pore collapse during ductile flow of the clay matrix. This study provides a microphysical basis to relate microstructures to macroscopic observations of strength and permeability of the Main Fault, and extrapolating fault properties in long-term deformation.

scholarly journals Deformation mechanisms and evolution of the microstructure of gouge in the Main Fault in Opalinus Clay in the Mont Terri rock laboratory (CH)

Solid Earth ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 1-24 ◽  
Author(s):  
Ben Laurich ◽  
Janos L. Urai ◽  
Christian Vollmer ◽  
Christophe Nussbaum
Keyword(s):  
Electron Microscopy ◽  
Fault Zone ◽  
Shear Zones ◽  
Deformation Mechanisms ◽  
Opalinus Clay ◽  
Rock Laboratory ◽  
Main Fault ◽  
Clay Formation ◽  
Mont Terri ◽  
Mont Terri Rock Laboratory

Abstract. We studied gouge from an upper-crustal, low-offset reverse fault in slightly overconsolidated claystone in the Mont Terri rock laboratory (Switzerland). The laboratory is designed to evaluate the suitability of the Opalinus Clay formation (OPA) to host a repository for radioactive waste. The gouge occurs in thin bands and lenses in the fault zone; it is darker in color and less fissile than the surrounding rock. It shows a matrix-based, P-foliated microfabric bordered and truncated by micrometer-thin shear zones consisting of aligned clay grains, as shown with broad-ion-beam scanning electron microscopy (BIB-SEM) and optical microscopy. Selected area electron diffraction based on transmission electron microscopy (TEM) shows evidence for randomly oriented nanometer-sized clay particles in the gouge matrix, surrounding larger elongated phyllosilicates with a strict P foliation. For the first time for the OPA, we report the occurrence of amorphous SiO2 grains within the gouge. Gouge has lower SEM-visible porosity and almost no calcite grains compared to the undeformed OPA. We present two hypotheses to explain the origin of gouge in the Main Fault: (i) authigenic generation consisting of fluid-mediated removal of calcite from the deforming OPA during shearing and (ii) clay smear consisting of mechanical smearing of calcite-poor (yet to be identified) source layers into the fault zone. Based on our data we prefer the first or a combination of both, but more work is needed to resolve this. Microstructures indicate a range of deformation mechanisms including solution–precipitation processes and a gouge that is weaker than the OPA because of the lower fraction of hard grains. For gouge, we infer a more rate-dependent frictional rheology than suggested from laboratory experiments on the undeformed OPA.

scholarly journals In-situ diffusion of HTO, 22Na+, Cs+ and I- in Opalinus Clay at the Mont Terri underground rock laboratory

2004 ◽  
Vol 92 (9-11) ◽  
Author(s):  
Luc R. Van Loon ◽  
P. Wersin ◽  
J. M. Soler ◽  
J. Eikenberg ◽  
Th. Gimmi ◽  
...  
Keyword(s):  
Research Laboratory ◽  
Opalinus Clay ◽  
Small Scale ◽  
Diffusion Data ◽  
Rock Laboratory ◽  
In Situ Diffusion ◽  
Mont Terri ◽  
Underground Research Laboratory ◽  
Diffusion Properties

SummaryThe diffusion properties of the Opalinus Clay were studied in the underground research laboratory at Mont Terri (Canton Jura, Switzerland) and the results were compared with diffusion data measured in the laboratory on small-scale samples. The diffusion of HTO,

The Growth of Herpesvirus mulatto in Human Fibroblast

1974 ◽  
Vol 32 ◽  
pp. 244-245
Author(s):  
Glennelle Washington ◽  
Philip P. McGrath ◽  
Peter R. Graze ◽  
Ivor Royston
Keyword(s):  
Rhesus Monkey ◽  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Peripheral Blood ◽  
Human Fibroblast ◽  
Rhesus Monkeys ◽  
Human Fibroblasts ◽  
Electron Microscopic ◽  
Specific Antisera ◽  
Peripheral Blood Leucocytes

Herpes-like viruses were isolated from rhesus monkey peripheral blood leucocytes when co-cultivated with WI-38 cells. The virus was originally designated rhesus leucocyte-associated herpesvirus (LAHV) and subsequently called Herpesvirus mulatta (HVM). The original isolations were from juvenile rhesus monkeys shown to be free of antibody to rhesus cytomegalic virus. The virus could only be propagated in human or simian fibroblasts. Use of specific antisera developed from HVM showed no relationship between this virus and other herpesviruses. An electron microscopic study was undertaken to determine the morphology of Herpesvirus mulatta (HVM) in infected human fibroblasts.

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