## 3 Results  
Using the STMA, quantitative parameters of microfractures in thin sections were calculated. The mean length of one object (microfracture segment) was about 7.5 \(\mathrm{\SIUnitSymbolMicro m}\). The investigated area varied from 150 to 370 mm\({}^{2}\). Microstructural parameters are presented in Table 6 and in Figure 7. Samples 57-1 and 60-2 show maximum cumulative length and maximum number of microfractures (see Table 6 and Figure 7A,B). Minimal values of these parameters are observed in samples 55-3, 55-4, 81-4 and 81-5. The remaining samples are characterized by average values. The L/S ratios (see Table 6 and Figure 7C) reached maxima in samples 57-1, 60-2, 60-3, 61-5 and minima in samples 55-4, 81-3, 81-4, 81-5. Maximum values of the fracture intensity (F = N/L) [99] were observed in samples 61-5, 81-3, 81-4, 81-5 and the minimum values-in samples 55-4, 60-2 (see Table 6 and Figure 7D). In general, the distribution of the fracture intensity is extremely nonuniform. Porosity and permeability can be most informative parameters for assessing the degree of deformations, since they are directly related to the physical properties of rocks. Porosity and permeability vary in a similar manner (see Table 6 and Figure 7E,F). Four clusters can be distinguished. The first cluster shows increased values of porosity and permeability. It includes samples 60-2, 60-3 and 61-5. The second cluster shows average values of porosity/permeability typical for samples 57-1, 58-1, 59-1 and 59-2. The third cluster includes only sample 60-1 and is associated with below-average values. Minimum values characterize the fourth cluster, which includes samples 55-1, 55-3, 55-4, 56-1, 81-3, 81-4 and 81-5. Figure 8 shows distributions of L/S and N/L versus permeability. Figure 7: Graphs of the distribution of cumulative length (**A**), number of microfractures (**B**), L/S (**C**), Fracture intensity (**D**), porosity (**E**) and permeability (**F**) of microfractures in oriented thin sections. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Cumulative** & **Mean** & **Number of** & **Studied** & **Fracture** & & & & \\  & **Length,** & **Aperture,** & **Objects** & **Area, mm2** & **Intensity** & **L/S** & **Porosity, \%** & **Permeability,** \\  & **mm (L)** & **Microns (e)** & **(N)** & **(S)** & **F = N/L** & & & **m2** \\ \hline
55-1 & 2416.76 & 3.1 & 326,112 & 282.52  
Fracture density maps (P20) [100] of the identified microfractures were built to assess the most permeable zones in the thin section. These maps show the areal distribution of microfractures (Figure 9). Figure 8: Graphs of the distribution of L/S (**A**) and N/L (**B**) versus permeability. Figure 9: Fracture density (P20) maps and rose diagrams of microfractures in oriented thin sections. Microfractures in the samples 56-1, 57-1, 59-1, 60-2, 60-3 and 61-5 have relatively uniform spatial distributions. In other thin sections, the distribution of microfractures is extremely uneven. Most often, the areas of maximum density of microfractures are confined to linearly elongated zones oriented in a certain manner. In sample 55-3, the density diagram clearly shows the contact of two rocks, which strike northeast. The rocks differ in the density of microfractures. Figure 9 also shows rose diagrams microfracture orientation. The results of orientation measurements can be used to reconstruct stress-strain fields, as well as to indirectly assess the degree of deformations that resulted in the origination of microfracture ensembles. In this paper, only the predominant directions of strikes of microfracture ensembles are considered. For a more detailed analysis, it is necessary to rank microfractures over length and orientation intervals, as well as structural and genetic types in order to identify individual ensembles associated with certain stages of deformations and parameters of the acting stress-strain field [6; 7; 8; 9].