Study of geology and Carboniferous subcrop topography upon engineering geological mapping of Moscow territory

Abstract Carboniferous deposits in Moscow are composed of interlaying carbonate and clay-marl massifs. The roof of Carboniferous deposits occurs at a depth 5–150 m below the surface. It has been affected by several generations of river erosion. Carbonate layers consist mainly of limestones karstified to a different extent. Suffosion development in overlaying sandy-clayey and sandy horizons resulting in karst-suffosion sinkholes and surface subsidence are related to the ancient buried karst forms. The geological map of Carboniferous deposits is compiled to a scale of 1: 10 000 for the entire territory of Moscow. The map shows the geological structure at the roof of Carboniferous deposits. It also displays the spatial distribution of various stratigraphical and lithological series of Carboniferous system, the subcrop topography of the Carboniferous deposits and thalwegs of pre-Jurassic and pre-Pleistocene (pre-glacial) buried river valleys and gullies. The specifics of karst development in Carboniferous limestone massifs are studied. Karstification and fracturing distribution is analysed in connection with the ancient topography. The geological map of Carboniferous deposits is one of the principal maps for compiling the map of karst and karst-suffosion hazard and the map of engineering geological zoning of Moscow.