Exotic sediments in the Devonian thickness of the Middle Timan

Sedimentary bodies unusual for the Devonian thickness of the Middle Timan are described: apepal illite layer, calcite bodies with "cone-in-cone" texture in close association with the basic tuff layer, the original conglomerate with dolomitic cement where the washed-up calcite concretions perform the role of pebbles. In deposits of the Tsilma suite the clay layer as an important regional marker was found. Clay is represented by illite which has developed in apepal montmorillonite. The existence of the layer indicates the continuing volcanic activity in the Tsilma time. In the section described above, a double layer of tuff (upper) and calcite with a “cone-in-cone” (lower) structure was found. Distinctive features of calcite lenses are: holocrystalline architecture, instead of fibrous, sharp increase in the content of light isotope of carbon (δ13C PDB to -22.5%). The unusual lens of the washed-up calcite concretions was found. The carbonate of cement is of dolomitic composition. The conclusion about shortterm approaches of the salty sea at the end of the Ust’chirka time is made. The research results help to detail the history of development of the Devonian terrigenous deposits.