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Swiss Journal of Geosciences
Fig. 9 | Swiss Journal of Geosciences

Fig. 9

From: Microstructural characterization of natural fractures and faults in the Opalinus Clay: insights from a deep drilling campaign across central northern Switzerland

Fig. 9

Three examples of thrust faults associated with subhorizontal and fibrous veins. White arrows indicate downhole arrows. a–c Macroscopic photographs of thrust faults (with slickenfibres) parallel to fibrous calcite veins (a: sample STA2_1_793.15, b: sample STA3_1_851.27, c: sample BOZ2_1_531.77). d Optical light micrograph showing fibrous crack-seal vein, with calcite fibres perpendicular to the slickensides on the upper slip surface (sample BOZ2_1_527.87). e–f Optical light micrographs showing fibrous veins disrupted by slickensides (in (e) sample BOZ2_1_531.77, in (f) sample STA2_1_793.15). g Optical light micrograph shows multiple slickensides localised on the dip slip surface of a fibrous calcite vein (sample BOZ2_1_531.77)

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