Deep structure of the Moscow Aulacogene in the western part of Moscow

Geological and geomorphological studies of the Moscow Aulacogene in the western part of Moscow suburbs have been conducted. This deep structure has been studied by microseismic sounding. The resulting section presents the faults which frame the Teplostanskii Graben in the south (Ramenskii or Butovskii, expressed on the surface as a ledge in the relief) and in the north (Pavlovo-Posadskii, being traced on the surface as a series of lineaments and the valley of Setun’ River). The position of the surface Archean-Lower Proterozoic crystalline basement within the limits of the graben and within the limits of buried elevated blocks (Krasnogorskii and Tumsk-Shaturskii) frame it in the north and south, respectively. Additionally, another fault has been identified in the central part of the graben: the Solntsevskii fault, which has a north-western course and which separates the deflection of the basement in two blocks that are sunken in a slightly different degree. The low-velocity horizons of the Riphean-Vendian complex which make up the graben at depths of 2 to 4.5 km have been found. Down to depths of 15 km, as a component of the upper crust, the graben is underlain by a high-velocity material which also forms the upper part of the section of the crystalline basement in the neighboring elevated block. A low-velocity block of the lithosphere is located in the larger (northern) part of the graben deeper (down to 40 km) beneath the zones of Pavlovo-Posadskii and Solntsevskii faults; in the southern part there is a high-velocity block. In the fault zones framing the graben in the north and south, the surface layer and soil displays a flow of juvenile hydrogen and helium which exceeds several tenfold the background values. According to the collected data, the Teplostanskii Graben has roots traceable through the entire crust and penetrating into the upper mantle.