Tectonic evolution around the Mont Terri rock laboratory, northwestern Swiss Jura: constraints from kinematic forward modelling

Nussbaum, Christophe; Kloppenburg, A.; Caër, Typhaine; Bossart, Paul

doi:10.1007/978-3-319-70458-6_3

Cited by 22 publications

(25 citation statements)

References 41 publications

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“…The (Nussbaum et al 2017) one 2-m long and two 50-cm long hydraulically inflatable packers (Fig. 3) made of a stainless steel central tube surrounded by sleeves with an inner layer of natural rubber and an outer layer of neoprene and reinforced with stainless steel wires.…”

Section: Bn Downhole Equipmentmentioning

confidence: 99%

Impact of the electron donor on in situ microbial nitrate reduction in Opalinus Clay: results from the Mont Terri rock laboratory (Switzerland)

et al. 2017

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At the Mont Terri rock laboratory (Switzerland), an in situ experiment is being carried out to examine the fate of nitrate leaching from nitrate-containing bituminized radioactive waste, in a clay host rock for geological disposal. Such a release of nitrate may cause a geochemical perturbation of the clay, possibly affecting some of the favorable characteristics of the host rock. In this in situ experiment, combined transport and reactivity of nitrate is studied inside anoxic and water-saturated chambers in a borehole in the Opalinus Clay. Continuous circulation of the solution from the borehole to the surface equipment allows a regular sampling and online monitoring of its chemical composition. In this paper, in situ microbial nitrate reduction in the Opalinus Clay is discussed, in the presence or absence of additional electron donors relevant for the disposal concept and likely to be released from nitrate-containing bituminized radioactive waste: acetate (simulating bitumen degradation products) and H 2 (originating from radiolysis and corrosion in the repository). The results of these tests indicate that-in case microorganisms would be active in the repository or the surrounding clay-microbial nitrate reduction can occur using electron donors naturally present in the clay (e.g. pyrite, dissolved organic matter). Nevertheless, non-reactive transport of nitrate in the clay is expected to be the main process. In contrast, when easily oxidizable electron donors would be available (e.g. acetate and H 2 ), the microbial activity will be strongly stimulated. Both in the presence of H 2 and acetate, nitrite and nitrogenous gases are predominantly produced, although some ammonium can also be formed when H 2 is present. The reduction of nitrate in the clay could have an impact on the redox conditions in the pore-water and might also lead to a gas-related perturbation of the host rock, depending on the electron donor used during denitrification.

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Section: Bn Downhole Equipmentmentioning

confidence: 99%

Impact of the electron donor on in situ microbial nitrate reduction in Opalinus Clay: results from the Mont Terri rock laboratory (Switzerland)

et al. 2017

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“…Veins at Mont Terri occur in structures that can be attributed to thrust-fault systems that developed during the formation of the anticline (Nussbaum et al 2011(Nussbaum et al , 2017. In spite of substantial brittle deformation, veins in Opalinus Clay are infrequent and thin, indicating that fluid flow across the formation during deformation was limited.…”

Section: Structural Features and Petrography Of Veinsmentioning

confidence: 99%

“…Within the Main Fault (shown in Fig. 1), the largest thrust fault within the Mont Terri rock laboratory (Nussbaum et al 2011(Nussbaum et al , 2017, veins are typically \ 1 mm thick and also occur within a few metres around the fault, documenting a diffuse pattern of deformation and vein precipitation.…”

Section: Structural Features and Petrography Of Veinsmentioning

confidence: 99%

Pore-water evolution and solute-transport mechanisms in Opalinus Clay at Mont Terri and Mont Russelin (Canton Jura, Switzerland)

Mazurek

Haller

2017

Mont Terri Rock Laboratory, 20 Years

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Data pertinent to pore-water composition in Opalinus Clay in the Mont Terri and Mont Russelin anticlines have been collected over the last 20 years from longterm in situ pore-water sampling in dedicated boreholes, from laboratory analyses on drillcores and from the geochemical characteristics of vein infills. Together with independent knowledge on regional geology, an attempt is made here to constrain the geochemical evolution of the pore-waters. Following basin inversion and the establishement of continental conditions in the late Cretaceous, the Malm limestones acted as a fresh-water upper boundary leading to progressive out-diffusion of salinity from the originally marine pore-waters of the Jurassic low-permeability sequence. Model calculations suggest that at the end of the Palaeogene, pore-water salinity in Opalinus Clay was about half the original value. In the Chattian/Aquitanian, partial evaporation of sea-water occurred. It is postulated that brines diffused into the underlying sequence over a period of several Myr, resulting in an increase of salinity in Opalinus Clay to levels observed today. This hypothesis is further supported by the isotopic signatures of SO 4 2-and 87 Sr/ 86 Sr in current pore-waters. These are not simple binary mixtures of sea and meteoric water, but their Cl -and stable water-isotope signatures can be potentially explained by a component of partially evaporated sea-water. After the re-establishment of fresh-water conditions on the surface and the formation of the Jura Fold and Thrust Belt, erosion caused the activation of aquifers embedding the low-permeability sequence, leading to the curved profiles of various pore-water tracers that are observed today. Fluid flow triggered by deformation events during thrusting and folding of the anticlines occurred and is documented by infrequent vein infills in major fault structures. However, this flow was spatially focussed and of limited duration and so did not markedly affect the bulk pore-water.

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“…From thin section microscope observations, the rock displays a fine grain fabric with heterogeneities. The clay (Nussbaum et al 2017) matrix is essentially formed of detrital particles of less than 1 lm of illite and illite-smectite mixed layers, with minor 10-50 lm sized flakes of biotite, muscovite, and chlorite. The carbonate fraction consists of calcite test and shell fragments and diagenetic carbonates including calcite (major micrite, sparite, and rare euhedral grains), dolomite/ ankerite (essentially euhedral grains) and siderite (disseminated lm-sized grains, rare clusters).…”

Section: Geological Context and Rock Characteristicsmentioning

confidence: 99%

Natural gas extraction and artificial gas injection experiments in Opalinus Clay, Mont Terri rock laboratory (Switzerland)

Vinsot

Appelo²,

Lundy

et al. 2017

Swiss J Geosci

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Two experiments have been installed at Mont Terri in 2004 and 2009 that allowed gas circulation within a borehole at a pressure between 1 and 2 bar. These experiments made it possible to observe the natural gases that were initially dissolved in pore-water degassing into the borehole and to monitor their content evolution in the borehole over several years. They also allowed for inert (He, Ne) and reactive (H 2 ) gases to be injected into the borehole with the aim either to determine their diffusion properties into the rock pore-water or to evaluate their removal reaction kinetics. The natural gases identified were CO 2 , light alkanes, He, and more importantly N 2 . The natural concentration of four gases in Opalinus Clay porewater was evaluated at the experiment location: N 2 2.2 mmol/L ± 25%, CH 4 0.30 mmol/L ± 25%, C 2 H 6 0.023 mmol/L ± 25%, C 3 H 8 0.012 mmol/L ± 25%.Retention properties of methane, ethane, and propane were estimated. Ne injection tests helped to characterize rock diffusion properties regarding the dissolved inert gases. These experimental results are highly relevant towards evaluating how the fluid composition could possibly evolve in the drifts of a radioactive waste disposal facility.

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Tectonic evolution around the Mont Terri rock laboratory, northwestern Swiss Jura: constraints from kinematic forward modelling

Cited by 22 publications

References 41 publications

Impact of the electron donor on in situ microbial nitrate reduction in Opalinus Clay: results from the Mont Terri rock laboratory (Switzerland)

Impact of the electron donor on in situ microbial nitrate reduction in Opalinus Clay: results from the Mont Terri rock laboratory (Switzerland)

Pore-water evolution and solute-transport mechanisms in Opalinus Clay at Mont Terri and Mont Russelin (Canton Jura, Switzerland)

Natural gas extraction and artificial gas injection experiments in Opalinus Clay, Mont Terri rock laboratory (Switzerland)

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