An outcrop of Carboniferous – Permian clastic rocks located along the Sava river near Črnuče north of Ljubljana was studied to analyze tectonic structures. The studied section with a total stratigraphic thickness of 30 m comprises fine-grained sandstones and very-fine grained slates. The rocks were examined with X-ray diffraction and with optical microscopy. In both types of rock, metamorphic minerals such as albite, muscovite, clorite and illite are present. The rocks exhibit a low degree of metamorfism, however, SEM investigation and Raman spectrometry would additionally be required for exact determination of metamorphic grade. In structural analysis, various mesoscopic structrures such as joints, shear fractures, folds, faults and crenulation clevage were described and interpreted, and their orientations were measured. Orientations of structures were analysed in spherical projection to determine kinematic axes of deformation episodes, which produced the structures. Two groups of tensional veins, implying NE-SE and ESE-WNW directed extension were identified. Relative timing of these vein families, and their relative age with respect to shortening structures, was not possible to determine. The phase of NE-SE directed extension could be correlated to Mid-Miocene regional extension documented in the literature. Contractional structures, which include mesoscopic reverse faults and folds, crenulation cleavage, en echelon shear joints and conjugate fractures imply two phases of thrusting-related shortening. In the first, older phase the thrusting was SE to SSE-directed. This phase is characterized by ductile deformations and formation of crenulation cleavage, therefore I assume that during this stage the rocks were burried at a greater depths than today, and that this phase was probably coeval with metamorphism. Second phase of shortening is NE-SW-oriented, which matches in direction the Eocene-Oligocene Dinaric thrusting episode. Structures of this phase are of more brittle character and were thus probably formed at lower presures and temperatures compared to the structures of the first phase.
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