Geologická stavba hydrogeologického rajonu 2242 (Kuřimská kotlina) a představy vývoje toku řeky Svratky v kenozoiku.

Hydrogeological district 2242 - the Kuřim Basin (HGD 2242) lies NNW of the Brno city. The project "Groundwater balance in the selected areas of the Czech Republic" implemented by the Czech Geological Survey provided an opportunity to process and interpret data from many earlier drilled boreholes, geological maps and other records from this HGD. Several new boreholes enabled new recordings of groundwater behaviour and also provided data on lithology. The well logging also allowed to upgrade the position of individual beds and their lithology. The character of NW termination of hydrogeological district was verified by geophysical methods on P1 and P2 profiles, where vertical electrical sounding (VES) and electrical profiling (DOP) in dipoledipole array were used. Electrical resistivity tomography (ERT), dipole electromagnetic profiling (DEMP) and shallow seismic refraction survey (MRS) were employed only in selected sections of the profiles. The Tišnov Fault (NW-SE trending zone) in particular demarcates areas with different development which is reflected in distribution of sediments of various stratigraphic levels. While the central part represents tectonically the most affected, and simultaneously the most sunken area with relatively large thickness of Badenian sediments (more than 100 m), the marginal parts in the NE (Sebrov, Milonice) and in the SW (Vohančice, Čebín-Chudčice and Jinačovice) represent remodelled relics of Lower Miocene valleys filled with Ottnangian sediments the thickness of which only rarely exceeds 50 meters. Moreover, the lithology of both the above-mentioned types of sediments is also different. Ottnangian sediments consist of a sequence of alternating sands, gravels and clays with coal seams. Lower Badenian sediments are represented by marine calcareous clays that form most of their thickness, whereas coarse-grained clastics occur only on their basis. One of the project objectives was also to create a contour model of the base of Miocene sediments. Consequently, a border line defining the extent of Miocene sediments was established. It should become a new boundary of the hydrogeological district enabling balancing the groundwater supply and demand in the future. This contour model was derived from data obtained from the newly drilled boreholes and from the results of geophysical methods that allowed to create a concept of changing paleoflow of the Svratka River during the Neogene and Quaternary. The Pre-Ottnangian course of the Paleo-Svratka River is not clear. It later sinks along the Tišnov Fault forming a pre-Badenian valley trending approximately in the direction of Stěpánovice-Drásov-Kuřim-Brno. The valley was later filled with marine sediments markedly exceeding the current relief level. The tectonic vertical movements and blocks tilting continued in Badenian and post-Badenian time so the Svratka River direction moved to its recent position maybe partly similar to pre-Ottnangian. [ABSTRACT FROM AUTHOR]