Hostname: page-component-6766d58669-rxg44 Total loading time: 0 Render date: 2026-05-20T09:23:59.216Z Has data issue: false hasContentIssue false
  • English
  • Français

Chemical tracing and isotopic dating of authigenic illite-type minerals in centimeter-sized gouges of the ‘Main Fault’ within the Opalinus Clay (Switzerland)

Published online by Cambridge University Press:  17 March 2025

Norbert Clauer ,
Christophe Nussbaum Open the ORCID record for Christophe Nussbaum [Opens in a new window] ,
Marie-Christine Boiron  and
Marc Ulrich Open the ORCID record for Marc Ulrich [Opens in a new window]
Norbert Clauer*
Affiliation:
Institut des Sciences de la Terre et de l’Environnement de Strasbourg, Université de Strasbourg (UdS/CNRS), 67084 Strasbourg, France
Christophe Nussbaum
Affiliation:
Swiss Geological Survey, Federal Office of Topography Swisstopo, 3084 Wabern, Switzerland
Marie-Christine Boiron
Affiliation:
Université de Lorraine, CNRS, GeoRessources Research Unit, 54000 Nancy, France
Marc Ulrich
Affiliation:
Institut des Sciences de la Terre et de l’Environnement de Strasbourg, Université de Strasbourg (UdS/CNRS), 67084 Strasbourg, France
*
Corresponding author: Norbert Clauer; Email: nclauer@unistra.fr
Get access Rights & Permissions [Opens in a new window]

Abstract

Various minerals have crystallized in centimeter-sized gouges and in adjacent scaly clays of the Main Fault intersecting the Opalinus Clay within the Mont Terri underground rock laboratory (Switzerland). Authigenic illite-type crystals, for instance, formed idiomorphic overgrowths on older detrital mica-type agglomerates in the gouge matrices and in their highly deformed surrounding damage zones. This heterogeneous illite crystallization was induced by local temperature increases due to the friction during faulting and to circulation of hot fluids, more in the highly deformed gouge rims than in the gouge matrices themselves. The aggregation of authigenic illite with detrital counterparts in the size separates made it difficult to do any quantitative distinction, and therefore any direct isotopic age dating. This incomplete separation of the detrital from authigenic illite in size separates of the gouges and the scaly clays, even down to nanometer size, needed a theoretical K-Ar age extrapolation for the authigenic illite fraction at ~8.8±0.9 Ma. This estimated age is based on the K content of a theoretically pure authigenic fraction determined by in situ analysis relative to estimated K contents of the detrital counterparts.

The superposition of the micro-X-ray fluorescence Na and Cl maps visualizes a few veins filled with salts across an examined gouge, showing that fluids flowed through it, as well as through its highly deformed rims, while diffusing discretely into the surrounding matrix. The combined Fe and S micro-X-ray fluorescence maps of the examined materials also showed numerous pyrite agglomerates systematically associated with P, which indicates an occurrence of organic matter related to pyrite alteration. This organic matter induced local reducing conditions that were confirmed by REE spectra in the newly crystallized clay minerals of the fault features, carried by flowing fluids into the gouges. No geochemical argument suggests that the gouges are more or less permeable, at present, than the nearby undeformed Opalinus Clay. However, they were certainly more or less permeable at one point, probably during faulting, as K had to be supplied to explain the illite authigenesis detected in them and, to some extent, in the nearby scaly clays. Such permeability is also demonstrated by the systematic occurrence of salts in the micro-veins throughout the observed gouge and in its highly deformed rims that had to crystallize from fluids flowing during the deformation episode. Clearly, both the shape of the drains in and around the gouges and their systematic infilling by salts exclude technical artifacts claimed sometimes to deny any opening of the gouge volumes.

Keywords

centimeter-sized gouges and scaly claysK-Ar datingMain Fault tectonic environmentmineral alterations and authigenesesmulti-method elemental tracingOpalinus Clay formation

Information

Type
Original Paper
Information
Clays and Clay Minerals , Volume 73 , 2025 , e16
Check for updates
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of The Clay Minerals Society

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable

References

Aldega, L., Viola, G., Casas-Sainz, A., Marcén, M., Roman-Berdiel, T., & van der Lelij, R. (2019). Unraveling multiple thermotectonic events accommodated by crustal-scale faults in Northern Iberia, Spain: insights from K-Ar dating of clay gouges. Tectonics, 38, 3629–3651.10.1029/2019TC005585CrossRefGoogle Scholar
Bonhomme, M., Thuizat, R., Pinault, Y., Clauer, N., Wendling, R., & Winkler, R. (1975). Méthode de datation potassium-argon. Appareillage et techniques. Note Technique de l’Institut de Géologie de Strasbourg, France, 3, 53 pp.Google Scholar
Bossart, P., Bernier, F., Birkholzer, J., Bruggeman, C., Connolli, P., Dewonck, S., Fukaya, M., Herfort, M., Jensen, M., Matray, J.-M., Mayor, J. C., Moeri, A., Oyama, T., Schuster, K., Shigeta, N., Vietor, T., & Wieczorek, K. (2017). Mont Terri rock laboratory, 20 years of research: introduction, site characteristics and overview of experiments. Swiss Journal of Geosciences, 110. doi: 10.1007/s00015-016-0236-1CrossRefGoogle Scholar
Brindley, G., & Brown, G. (eds) (1980). Crystal Structures of Clay Minerals and their X-ray Identification. Monograph 5, Mineralogical Society, London, 495 pp.10.1180/mono-5CrossRefGoogle Scholar
Bundesamt für Energie (2008). Sachplan geologische Tiefenlager: Konzeptteil. Bern, Schweiz: Bundesamt für Energie BFE. http://www.bfe.admin.chGoogle Scholar
Caine, J.S., Evans, J.P., & Forster, C.B. (1996). Fault zone architecture and permeability structure. Geology, 24, 1025–1028.10.1130/0091-7613(1996)024<1025:FZAAPS>2.3.CO;22.3.CO;2>CrossRefGoogle Scholar
Carboni, F., Viola, G., Aldega, L., van der Lelij, R., Brozzetti, F., & Barchi, M. (2020). K-Ar fault gouge dating of Neogene thrusting: the case of the siliciclastic deposits of the Trasimeno Tectonic Wedge (Northern Apennines, Italy). Italian Journal of Geosciences, 139, 300–308.10.3301/IJG.2020.06CrossRefGoogle Scholar
Clauer, N., & Chaudhuri, S. (1995). Clays in Crustal Environments . Isotope Dating and Tracing, 359 pp. Springer Verlag, Heidelberg, New York.Google Scholar
Clauer, N., & Chaudhuri, S. (1998). Isotopic dating of very low-grade metasedimentary and metavolcanic rocks: techniques and methods. Low-Grade Metamorphism (ed. Frey, M. & Robinson, D.), 202–226. Blackwell Science, Oxford, UK.10.1002/9781444313345.ch7CrossRefGoogle Scholar
Clauer, N., Środoń, J., Francú, J., & Šucha, V. (1997). K-Ar dating of illite fundamental particles separated from illite/smectite. Clay Minerals, 32, 181–196.10.1180/claymin.1997.032.2.02CrossRefGoogle Scholar
Clauer, N., Techer, I., Nussbaum, C., & Laurich, B. (2017a). Geochemical signature of paleofluids in microstructures of the Main Fault in the Opalinus Clay of the Mont Terri rock laboratory, Switzerland. Swiss Journal of Geosciences, 5, 107–130.10.1007/978-3-319-70458-6_6CrossRefGoogle Scholar
Clauer, N., Boiron, M.C., Nussbaum, C., & Techer, I. (2017b) Chemical clues for the extent and timing of fluid-mineral interactions in the gouge(s) from the Main Fault in the OPA. 35th Technical Meeting (TM-35), Porrentruy, 8–9 February 2017.Google Scholar
Cutten, H.N., Zwingmann, H., Uysal, T., Todd, A., & Johnson, S.P. (2021). Dating Proterozoic Fault movement using K-Ar geochronology of illite separated from lithified fault gouge. Government of Western Australia, Department of Mines, Industry Regulation and Safety, Report 214, 25 pp.Google Scholar
Farrell, N.J.C., Debenham, N., Wilson, L., Wilson, M.J., Healy, D., King, R.C., Holford, S.P., & Taylor, C.W. (2021). The effect of authigenic clays on fault zone permeability. Journal of Geophysical Research: Solid Earth, 126, e2021JB022615. https://doi.org/10.1029/2021JB022615.Google Scholar
Gromet, L.P., Haskin, L.A., Korotev, R.L., & Dymek, R.F. (1984). The ‘North American shale composite’: its compilation, major and trace element characteristics. Geochimica et Cosmochimica Acta, 48, 2469–2482.10.1016/0016-7037(84)90298-9CrossRefGoogle Scholar
Haines, S.H., & van der Pluijm, B.A. (2012). Patterns of mineral transformations in clay gouge, with examples from low-angle normal fault rocks in the western USA. Journal of Structural Geology, 43, 2–32.10.1016/j.jsg.2012.05.004CrossRefGoogle Scholar
Harper, C.T. (1970). Graphic solution to the problem of 40Ar loss from metamorphic minerals. Eclogae Geologicae Helvetiae, 63, 119–140.Google Scholar
Hobbs, B.E., Means, W.D., & Williams, P.F. (1976). An Outline of Structural Geology, 571 pp. Wiley, New York, USA.Google Scholar
Hoffman, J., Hower, J., & Aronson, J.L. (1976). Radiometric dating of time of thrusting in the disturbed belt of Montana. Geology, 4, 16–20.10.1130/0091-7613(1976)4<16:RDOTOT>2.0.CO;22.0.CO;2>CrossRefGoogle Scholar
Holdsworth, R.E., Butler, C.A., & Roberts, A.M. (1997). The recognition of reactivation during continental deformation. Journal of the Geological Society, 154, 73–78.10.1144/gsjgs.154.1.0073CrossRefGoogle Scholar
Jackson, M.L. (1975). Soil Chemical Analysis – Advanced Course, 386 pp. Madison, Wisconsin, USA.Google Scholar
Jaeggi, D., Laurich, B., Nussbaum, C., Schuster, K., & Connolly, P. (2018). Tectonic structure of the ‘Main Fault’ in the Opalinus Clay, Mont Terri rock laboratory (Switzerland). Swiss Journal of Geosciences, 5, 69–86.10.1007/978-3-319-70458-6_4CrossRefGoogle Scholar
Kirschner, D.L., Sharp, Z.D., & Masson, H. (1995). Oxygen isotope thermometry of quartz calcite veins unraveling the thermal-tectonic history of the sub-greenschist facies Morcles nappe (Swiss Alpes). Geological Society of America Bulletin, 107, 1145–1156.10.1130/0016-7606(1995)107<1145:OITOQC>2.3.CO;22.3.CO;2>CrossRefGoogle Scholar
Kligfield, R., Hunziker, J., Dallmeyer, R.D., & Schamel, S. (1986). Dating of deformation phases using K-Ar and 40Ar/39Ar techniques: results from the Northern Apennines. Journal of Structural Geology, 8, 781–798.10.1016/0191-8141(86)90025-8CrossRefGoogle Scholar
Kralik, M. (1982). Rb-Sr determinations on Precambrian carbonate rocks of the Carpentarian McArthur Basin, Northern Territories, Australia. Precambrian Research, 18, 157–170.10.1016/0301-9268(82)90044-4CrossRefGoogle Scholar
Laurich, B. (2015). Evolution of microstructure and porosity in faulted Opalinus Clay. PhD Thesis, Rheinisch-Westfälische Techniche Hochschule (RWTH), Aachen, Germany.Google Scholar
Laurich, B., Urai, J.L., Desbois, G., Vollmer, C., & Nussbaum, C. (2014). 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 Mont Terri Underground Research Laboratory. Journal of Structural Geology, 67, 107–128.CrossRefGoogle Scholar
Laurich, B., Urai, J.L., & Nussbaum, C. (2017). Microstructures and deformation mechanisms in Opalinus Clays: insights from scaly clay from Main Fault in the Mont Terri rock laboratory. Solid Earth, 8, 1–24.10.5194/se-8-27-2017CrossRefGoogle Scholar
Laurich, B., Urai, J.L., Vollmer, C., & Nussbaum, C. (2018). Deformation mechanisms and evolution of the microstructures of gouge in the Main Fault in Opalinus Clay in the Mont Terri rock laboratory (CH). Solid Earth, 9, 1–24.10.5194/se-9-1-2018CrossRefGoogle Scholar
Laverret, E., Clauer, N., Fallick, A., Mercadier, J., Patrier, P., Beaufort, D., & Bruneton, P. (2010). K-Ar dating and dO-dD tracing of illitization within and outside the Shea Creek uranium prospect, Athabasca Basin, Canada. Applied Geochemistry, 25, 856–871.10.1016/j.apgeochem.2010.03.004CrossRefGoogle Scholar
Lee, J.Y., Marti, K., Severinghaus, J.P., Kawamura, K., Yoo, H.S., Lee, J.B., & Kim, J.S. (2006). A redetermination of the isotopic abundances of atmospheric Ar. Geochimica et Cosmochimica Acta, 70, 4507–4512.10.1016/j.gca.2006.06.1563CrossRefGoogle Scholar
Liewig, N., Clauer, N., & Sommer, F. (1987). Rb-Sr and K-Ar dating of clay diagenesis in Jurassic sandstone oil reservoir, North Sea. American Association of Petroleum Geologists Bulletin, 71, 1467–1474.Google Scholar
MacRae, M.D., Nesbitt, H.W., & Kronberg, B.I. (1992). Development of a positive Eu anomaly during diagenesis. Earth and Planetary Science Letters, 109, 585–591.10.1016/0012-821X(92)90116-DCrossRefGoogle Scholar
Mazurek, M., Hurford, A.J., & Leu, W. (2006). Unravelling the multi-stage burial history of the Swiss Molasse Basin: integration of apatite fission track, vitrinite reflectance and biomarker isomerisation analysis. Basin Research, 18, 27–50.10.1111/j.1365-2117.2006.00286.xCrossRefGoogle Scholar
McCarty, D.K., Sakharov, B.A., & Drits, V. (2008). Early clay diagenesis in Gulf Coast sediments: new insights from XRD profile modeling. Clays and Clay Minerals, 56, 359–379.10.1346/CCMN.2008.0560306CrossRefGoogle Scholar
Meunier, A. (2005). Clays, 472 pp. Springer-Verlag, Heildeberg, Germany.Google Scholar
Mottram, C.M., Kellett, D.A., Barresi, T., Zwingmann, H., Friend, M., Todd, A., & Percival, J.B. (2020). Syncing fault rock clocks: direct comparison of U-Pb carbonate and K-Ar illite fault dating methods. Geology, 48, 1179–1183.CrossRefGoogle Scholar
Nussbaum, C., Amann, F., Aubourg, C., & Bossart, P. (2011). Analysis of tectonic structures and excavation induced fractures in the Opalinus Clay, Mont Terri underground rock laboratory (Switzerland). Swiss Journal of Geosciences, 104, 187–210.10.1007/s00015-011-0070-4CrossRefGoogle Scholar
Nussbaum, C., Kloppenburg, A., Caër, T., & Bossart, P. (2017). Tectonic evolution around the Mont Terri rock laboratory, northwestern Swiss Jura: constraints from kinematic forward modeling. Journal of Geosciences, 5, 41–68.Google Scholar
Odin, G.S. & 35 collaborators (1982). Interlaboratory standards for dating purposes. In Numerical Dating in Stratigraphy (ed. Odin, G.S.). John Wiley & Sons, Chichester, UK.Google Scholar
Orellana, L.F., Violay, M., Henry, P., Guglielmi, Y., & Nussbaum, C. (2017). Petro-physical characterization of the Main Fault at the Mont Terri Laboratory. 7th International Conference on Clays in Natural and Engineered Barriers for Radioactive Waste Confinement, Book of Abstracts, p. 268.Google Scholar
Pevear, D.R. (1999). Illite and hydrocarbon exploration. Proceedings National Academy of Sciences, USA, 96, 3440–3446.Google Scholar
Pearson, F.J., Acros, D., Bath, D., Boisson, J.Y., Fernández, A.M., Gäbler, H.E., Gaucher, E., Gautschi, A., Griffault, L., Hernán, P., & Waber, H.N. (2003). Mont Terri Project: Geochemistry of Water in the Opalinus Clay Formation at the Mont Terri Rock Laboratory. Federal Office for Water and Geology (FOWG), Geology Series 5, 319 pp.Google Scholar
Samuel, J., Rouault, R., & Besnus, Y. (1985). Analyse multi-élémentaire standardisée des matériaux géologiques en spectrométrie d’émission par plasma à couplage inductif. Analusis, 13, 312–317.Google Scholar
Sanchez-Roa, C., Jimenez-Millàn, J., Abad, I., Faulkner, D.R., Nieto, F., & Garcia-Tortosa, F.J. (2016). Fibrous clay mineral authigenesis induced by fluid–rock interaction in the Galera fault zone (Betic Cordillera, SE Spain) and its influence on fault gouge frictional properties. Applied Clay Science, 134, 275–288.10.1016/j.clay.2016.06.023CrossRefGoogle Scholar
Sasseville, C., Tremblay, A., Clauer, N., & Liewig, N. (2008). K-Ar time constraints on the evolution of polydeformed fold-thrust belts: the case of the Northern Appalachians (southern Québec). Journal of Geodynamics, 45, 99–119.10.1016/j.jog.2007.07.004CrossRefGoogle Scholar
Scheiber, T., Viola, G., van der Lelij, R., Margreth, A., & Schönenberger, J. (2019). Microstructurally-constrained versus bulk fault gouge K-Ar dating. Journal of Structural Geology, 127, 103868.10.1016/j.jsg.2019.103868CrossRefGoogle Scholar
Scholz, C.H. (2002). The Mechanics of Earthquakes and Faulting, 2nd edn, 471 pp. Cambridge University Press, Cambridge, New York, Melbourne.10.1017/CBO9780511818516CrossRefGoogle Scholar
Środoń, J., Elsass, F., McHardy, W.J., & Morgan, D.J. (1992). Chemistry of illite/smectite inferred from TEM measurements of fundamental particles. Clay Minerals, 27, 137–158.10.1180/claymin.1992.027.2.01CrossRefGoogle Scholar
Steiger, R.H., & Jäger, E. (1977). Subcommision on geochronology: convention on the use of decay constants in geo- and cosmochronology. Earth and Planetary Science Letters, 36, 359–362.CrossRefGoogle Scholar
Tostevin, R., Shields, G.A., Tarbuck, G.M., He, T., Clarkson, O.M., & Wood, R.A. (2016). Effective use of cerium anomalies as a redox proxy in carbonate-dominated marine settings. Chemical Geology, 438, 146–162.10.1016/j.chemgeo.2016.06.027CrossRefGoogle Scholar
Ulrich, M., Munoz, M., Guillot, S., Cathelineau, M., Picard, C., Quesnel, B., Boulvais, P., & Couteau, C. (2014). Dissolution–precipitation processes governing the carbonation and silicification of the serpentinite sole of the New Caledonia ophiolite. Contributions to Mineralogy and Petrology, 167, 952–971.CrossRefGoogle Scholar
Velde, B., & Vasseur, G. (1992). Estimation of the diagenetic smectite to illite transformation in time-temperature space. American Mineralogist, 77, 967–976.Google Scholar
Vrolijk, P., & van der Pluijm, B.A. (1999). Clay gouges. Journal of Structural Geology, 21, 1039–1048.10.1016/S0191-8141(99)00103-0CrossRefGoogle Scholar
Zwingmann, H., Han, R., & Ree, J.-H. (2010). Cretaceous reactivation of the Deokpori Thrust, Taebaeksan Basin, South Korea, constrained by K-Ar dating of clayey fault gouge. Tectonics, 30. https://doi.org/10.1029/2010TC002829Google Scholar
Zwingmann, H., Berger, A., Eggenberger, U., Todd, A., & Herwegh, M. (2017). Testing high voltage electrical discharges in disintegrating claystone for isotopic and mineralogical studies: an example using Opalinus claystone. Clays and Clay Minerals, 65, 342–354.CrossRefGoogle Scholar