Shing Fm

The Daurechskiy, Uatasay, and Arg typesections are fully or largely represented by the Shing Fm (Resolution..., 1969)

Synonym: Shing suite

Reference section:

In the sections of the Daurech type, the suite is represented by uniform clayey dolomitized limestones. Based on the complexes of fossil organisms, the Bilfurak, Daurech, Mukhak, Khokhgalta, Yakkahonino, Nofin, and Zorhok layers are distinguished. In the Zorhok layers, the limestones become more coarse-bedded and gradually turn into dolomites. Above lie black medium- and thin-bedded dolomites of the lower Arg sub-suite, the lower part of which in this type of section still contains a complex of forms characteristic of the tops of the upper Wenlock (Shikorhon layers).

In sections of the Arg type, the entire lower Silurian, including the Shikorhon layers, is composed of thin-bedded clayey limestones of the Shing Fm. Distinguishing features of these sections are also their considerable thickness, the presence of interlayers of quartz sandstones and quartz-chlorite-sericite schists, and a relatively poor complex of fossils (Lavrusevich, Menakova, 1971).

Sections of the Zinakh type are widespread in the framing of the Ganza-Chimtarginsky Mountain node and are represented by the Zinakh layer, which occupies the same position in the section as the Shing suite. The thickness of the Zinakh layer is 400-700 m. It is represented by quartzite sandstones with interlayers of phyllitic schists, limestones, dolomites, and rarely altered diabases. (Lavrusevich, Menakova, 1971).

In different types of sections, the thickness of the suite varies from 230 (g. Daurech) to 770 m (r. Arg).

In the sections of the Daurech type, numerous stromatoporoids Clathrodictyon regulare (Rosen), C. microstriatellum Riab., C. cylindricum Riab., tabulates Palaeofavosites balticus (Rukhin), Favosites gothlandicus Lam., F. hisingeri M.-Edw. et H., Catenipora gotlandica (Yabe); rugose Streptelasma asiaticum Lavrus., Dinophyllum longum Lavrus., Cyathactis typus Soshk., Protopilophyllum cylindricum (Ivnsk), Calostylis denticulata (Kjerulf.), Ceriaster menakovae Lavrus., Entelophyllum articulatum (Wahl.), E. nikolaievae Lavrus., Holmophyllum progressivum Lavrus., Cystiphyllum cylindricum Lonsdale, Ketophyllumı rarum Lavrus., Yassia fasciculata Lavrus., et Ivnsk; brachiopods Resserella neocrassa (Nikif.), Virgiana barrandei (Billings), Pentamerus magianicus Menakova, Acanthospirifer edelschteini Menakova and other fossils (Lavrusevich, Menakova, 1966, 1971).

In the Zorhok layers, Clathrodictyon fastigiatum Nich., Cl. aff. cylindriforme Riab. and others.

In Shikorhon layers, a relatively poor complex of fossils (Lavrusevich, Menakova, 1971).

In Zinakh layer, the complex of fossils is similar to that of the Shing suite, but much poorer (Lavrusevich, Menakova, 1971).