Landslide Sediment Structures in Lower Carboniferous Terrigenous–Carbonate Rocks of the Kochkar Anticlinorium (Southern Urals)

The metamorphic framing of granite-gneiss domes in the Кochkar anticlinorium (Southern Urals) includes the Lower Carboniferous terrigenous-carbonate sequence that underwent zonal metamorphism of the epidote–amphibolite to greenschist facies. Numerous soft-sediment deformation structures were found in marbles of this sequence uncovered by the quarry at the Svetlinsk gold deposit and in the bedrock of the Eleninsk placer. The main structure types are represented by landslides associated with the laminar sediment flows and less often by seismites of various morphologies. The formation mechanism of these structures is associated with the underwater gravitational landslide of nonlithified sediments due to change in the seabed slope and the impact of earthquakes. The seismic activity was triggered by both the anticlinorium-bounding regional faults and, probably, the formation of granite-gneiss domes. The discovery of landslides and seismites in the terrigenous–carbonate sequences of the anticlinorium provides insight into its paleotectonic formation environment during the Late Paleozoic Ural collision. The structural position of carbonate rocks indicates the formation of granite-gneiss domes under shallow-water conditions in the anticlinorium.