Sedimentation Conditions, Material Composition, and Reconstruction of the Rock Composition of the Feeding Provinces of the Visean Terrigenous Stage of the Bashkir Dome (Based on the Results of the Study of the Borehole Core in the South of the Perm Territory)

Abstract

The lithologic-facial, mineralogical, petrographic, and lithogeochemical studies of Visean terrigenous sediments in the borehole section at the Bashkirian arch were carried out to clarify the sources of matter and sedimentation conditions. Terrigenous rocks of the Radayevsky and Bobrikovsky horizons are characterized by predominantly good sorting and pelletization of clastic material. A significant distance from the source of drifting is assumed. Terrigenous rocks of these horizons are sediments of the first and second sedimentation cycles. The rocks of the Tula horizon are characterized by average sorting and pelletization, which indicates the proximity of the drift source to the sedimentation basin. They are rocks of the first sedimentation cycle. The source of clastic material for the Radayevsky and Tula horizons was found to be rocks of acidic composition. For the beaver horizon, the acidic and the main source of drift was established. It is assumed that sedimentation of rocks occurred in coastal-marine conditions on the passive continental margin, with the inflow of clastic material from the inner parts of the East European Platform, due to overwashing of the early accumulated terrigenous rocks of the Devonian and Proterozoic, as well as destruction of the basement ledges, which were activated in the Early Visean time during the manifestation of folding. The presence of basic rocks in the Bobrikovsky horizon may indicate that the material came from the orogen.