Abstract
Over the last 18 years we have extensively studied an intra-Opalinus Clay fault zone that crops out within the Mont Terri rock laboratory in NW-Switzerland. We performed micro- and macrostructural characterization on four outcrops of this so-called “Main Fault”, which crosscuts the entire Mont Terri rock laboratory. Combining detailed structural mapping, analysis down to the nanometer-scale, and geophysical investigations leads to a better understanding of fault zones within clay-dominated lithologies. The multi-scale, multi-technique approach that we applied in this study on four individual outcrops is critical for describing such a complex system. In these four outcrops, we differentiate five macroscopic structural elements of the Main Fault and have studied their occurrence and spatial distribution. In general, scaly clay, including S–C bands (S = “schistosité” = cleavage, C = “cisaillement” = shear parallel to shear zone boundaries) and microfolds, occurs in isolated, sharply bound lenses and in larger zones at the top and bottom of the Main Fault. A cm-thin, continuous layer of gouge runs along the upper boundary of the fault zone. The non-scaly part shows rather low strain and consists of rhombohedral blocks of undeformed rock (horses), bound by slickensides. The lm-thin shear zones are considered to be elementary building blocks for the structural elements of the Main Fault. Direct comparison of the four studied outcrops to each other highlights the significant lateral variability of the Main Fault. In addition to a reduction in thickness from west to east, size and distribution of structural elements are highly variable. Correlation of these structural elements between closely spaced outcrops is not possible. Fortunately, the upper and lower boundary of the Main Fault, as well as thicker sheets of scaly clay, can be recognized using seismic attributes and thus yield indirect information about size and internal structure of fault zones in clay.
Editorial handling: P. Bossart and A. G. Milnes.
This is paper #3 of the Monte Terri Special Issue of the Swiss Journal of Geosciences (see Bossart et al. 2017, Table 3 and Fig. 7)
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Baur, S. (2014). Geological, Petrophysical and Geochemical Investigations of the Opalinus Clay Formation of the Underground Rock Laboratory Mont Terri, Switzerland. Master thesis, Albert-Ludwigs-University of Freiburg, Freiburg in Breisgau, Germany.
Blaesi, H. R., Moeri, A., & Bossart, P. (1996). Results of the Phase 1 drilling campaign. Mont Terri Technical Report, TR96-01. Federal Office of Topography (swisstopo), Wabern, Switzerland. http://www.mont-terri.ch.
Blenkinsop, T. G. (2000). Deformation microstructures and mechanisms in minerals and rocks (p. 150). Dordrecht: Kluwer Academic Publishers.
Bossart, P., Bernier, F., Birkholzer, J., Bruggeman, C., Connolli, P., Dewonck, S., et al. (2017). Mont Terri rock laboratory, 20 years: Introduction, site characteristics and overview of experiments. Swiss Journal of Geosciences, 110. https://doi.org/10.1007/s00015-016-0236-1.
Bossart, P., & Thury, M. (2008). Mont Terri Rock Laboratory. Project, programme 1996 to 2007 and results. Reports of the Swiss Geological Survey, 3. Federal Office of Topography (swisstopo), Wabern, Switzerland. http://www.mont-terri.ch.
Chester, F. M., Rowe, C., Ujiie, K., Kirkpatrick, J., Regalla, C., Remitti, F., et al. (2013). Structure and composition of the plateboundary slip zone for the 2011 Tohoku-Oki earthquake. Science, 342, 1208–1211.
Clauer, N., Techer, I., Nussbaum, C., & Laurich, B. (2017). Geochemical signatures of paleofluids in microstructures from Main Fault of the Opalinus Clay, Mont Terri rock laboratory (Switzerland). Swiss Journal of Geosciences, 110 (this issue).
Dick, P., Wittebroodt, C., Courbet, C., Sammaljärvi, J., Estève, I., Matray, J.-M., et al. (2016). The internal architecture and permeability structures of faults in shale formations. The Clay Minerals Society Workshop Lectures Series, 21(17), 227–242.
Dielforder, A., Vollstaedt, H., Vennemann, T., Berger, A., & Herwegh, M. (2015). Linking megathrust earthquakes to brittle deformation in a fossil accretionary complex. Nature Communications, 6, 7504.
Doblas, M., Mahecha, V., & Hoyos, M. (1997). Slickenside and fault surface kinematic indicators on active normal faults of the Alpine Betic cordilleras, Granada, southern Spain. Journal of Structural Geology, 19, 159–170.
Gratier, J.-P., Renard, F., & Vial, B. (2014). Postseismic pressure solution creep: Evidence and time-dependent change from dynamic indenting experiments. Journal of Geophysical Research Solid Earth, 119, 2764–2779.
Gschwind, S. (2013). The Relationship between Failure Behavior and Sedimentary Subfacies Types in the Sandy Facies of Opalinus Clay. Master thesis, Swiss Federal Institute of Technology in Zurich (ETH Zurich), Zurich, Switzerland.
Gudmundsson, A. (2001). Fluid overpressure and flow in fault zones: Field measurements and models. Tectonophysics, 336, 183–197.
Haines, S. H., Kaproth, B., Marone, C., Saffer, D., & van der Pluijm, B. (2013). Shear zones in clay-rich fault gouge: A laboratory study of fabric development and evolution. Journal of Structural Geology, 51, 206–225.
Hostettler, B., Reisdorf, A. G., Jaeggi, D., Deplazes, G., Blaesi, H. R., Morard, A., et al. (2017). Litho- and biostratigraphy of the Opalinus Clay and bounding formations in the Mont Terri rock laboratory (Switzerland). Swiss Journal of Geosciences, 110. https://doi.org/10.1007/s00015-016-0250-3
Houben, M. E., Desbois, G., & Urai, J. L. (2013). 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. Applied Clay Science, 71, 82–97.
Housen, B. A., Tobin, H. J., Labaume, P., Leitch, E. C., & Maltman, A. J. (1996). Strain decoupling across the decollement of the Barbados accretionary prism. Geology, 24, 127–130.
Ismat, Z. (2013). Block-supported cataclastic flow within the upper crust. Journal of Structural Geology, 56, 118–128.
Jaeggi, D., Lisjak, A., Gisiger, J., & Becker, J. (2013). FE-C experiment: Engineering part of full-scale emplacement experiment. Geological and structural mapping of the FE-tunnel including a photogrammetric method. Mont Terri Technical Note, TN2012-82. Federal Office of Topography (swisstopo), Wabern, Switzerland. http://www.mont-terri.ch.
Jaeggi, D., Wymann, L., Burrus, F., Becker, J., & Bossart, P. (2014). FE-E (EDZ-characterization in the vicinity of the FE-gallery) experiment. Synthesis of the excavation damaged zone (EDZ). Mont Terri Technical Note, TN2014-33. Federal Office of Topography (swisstopo), Wabern, Switzerland. http://www.mont-terri.ch.
Johansen, T. E. S., & Fossen, H. (2008). Internal geometry of fault damage zones in interbedded siliciclastic sediments. In C. A. J. Wibberley, W. Kurz, J. Imber, R. E. Holdsworth, & C. Collettini (Eds.), The internal structure of fault zones: Implications for mechanical and fluid-flow properties (pp. 35–56). London: The Geological Society of London.
Klinkenberg, M., Kaufhold, S., Dohrmann, R., & Siegesmund, S. (2009). Influence of carbonate microfabrics on the failure strength of claystones. Engineering Geology, 107, 42–54.
Koehn, D., & Passchier, C. W. (2000). Shear sense indicators in striped bedding-veins. Journal of Structural Geology, 22, 1141–1151.
Labaume, P., Maltman, A. J., Bolton, A., Tessier, D., Ogawa, Y., & Takizawas, S. (1997). Scaly fabrics in sheared clays from the decollement zone of the Barbados accretionary prism. In T. R. Shipley, Y. Ogawa, P. Blum, J. M. Bahr (Eds.), Proceedings of the ocean drilling program (pp. 59–77). USA: Texas A&M University.
Laurich, B. (2015). Evolution of microstructure and porosity in faulted Opalinus Clay. PhD thesis, RWTH Aachen University, Aachen, Germany.
Laurich, B., Urai, J. L., Desbois, G., Vollmer, C., & Nussbaum, C. (2014). Microstructural evolution of an incipient fault zone in Opalinus Clay: Insights from optical and electron microscopic study of iron-beam polished samples from the Main Fault in the Mont Terri underground research laboratory. Journal of Structural Geology, 67, 107–128.
Laurich, B., Urai, J. L., & Nussbaum, C. (2016). Microstructures and deformation mechanisms in Opalinus Clay: Insights from scaly clay from the Main Fault in the Mont Terri Rock Laboratory (CH). Journal Solid Earth. https://doi.org/10.5194/se-2016-94.
Marschall, P., Croisé, J., Schlickenrieder, L., Boisson, J.-Y., Vogel, P., & Yamamoto, S. (2004). Synthesis of hydrogeological investigations at the Mont Terri Site (phases 1 to 5). In P. Heitzmann (Ed.), Mont Terri Project—Hydrogeological synthesis—Osmotic flow. Bern: Reports of the Federal Office for Water and Geology, Geology Series, 6.
Marschall, P., Gimmi, T., & Horseman, S. (2005). Characterisation of gas transport properties of the Opalinus Clay. Oil & Gas Science and Technology, 60, 121–139.
Nussbaum, C., Bossart, P., Amann, F., & Aubourg, C. (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.
Nussbaum, C., Bossart, P., Zingg, A., Inderbitzin, L., & Steiger, H. (2001). Géométrie et cinématique d’une zone de chevauchement (,,Main Fault”) recoupant les Argiles à Opalinus dans le laboratoire souterrain du Mont Terri. Mont Terri Technical Report, TR2001-04. Federal Office of Topography (swisstopo), Wabern, Switzerland. http://www.mont-terri.ch.
Passchier, C. W., & Trouw, R. A. J. (1996). Microtectonics. Berlin: Springer.
Schuster, K. (2012). Detection of borehole disturbed zones and small scale rock heterogeneities with geophysical methods. In X. Li, L. Jing, & P. Blaser (Eds.), Proceedings of the EC-TIMODAZTHERESA International Conference, Impact of thermo-hydromechanical chemical (THMC) processes on the safety of underground radioactive waste repositories, Luxembourg, 29 Sep.–1 Oct. 2009 (pp. 135–145). Publications Office, 2012.
Schuster, K., Amann, F., Yong, S., Connolly, P., & Bossart, P. (2017). High-resolution mini-seismic methods applied in the Mont Terri rock laboratory (Switzerland). Swiss Journal of Geosciences, 110. https://doi.org/10.1007/s00015-016-0241-4.
Thoeny, R. (2014). Geomechanical analysis of excavation-induced rock mass behavior of faulted Opalinus Clay at the Mont Terri Underground Rock Laboratory (Switzerland). PhD thesis, Swiss Federal Institute of Technology in Zurich (ETH Zurich), Zurich, Switzerland.
Vannucchi, P., Maltman, A., Bettelli, G., & Clennell, B. (2003). On the nature of scaly fabric and scaly clay. Journal of Structural Geology, 25, 673–688.
Yong, S., Kaiser, P. K., & Loew, S. (2010). Influence of the tectonic shears on tunnel-induced fracturing. International Journal of Rock Mechanics and Mining Sciences, 47, 894–907.
Acknowledgements
The authors would like to thank the Mont Terri Project Partners swisstopo and Chevron for their financial contribution to the PS (Petrofabric and Strain) experiment. Both reviewers Marco Herwegh from University of Bern and Reto Thöny from AF Consult provided useful comments and helped to improve the manuscript. We thank Fabian Jäggi, Solothurn, for creating and improving the figures of this work.
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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). In: Bossart, P., Milnes, A. (eds) Mont Terri Rock Laboratory, 20 Years. Swiss Journal of Geosciences Supplement, vol 5. Birkhäuser, Cham. https://doi.org/10.1007/978-3-319-70458-6_4
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