The lithologic-paleontologic substantiation of the ilinskian subseries stratification of the Kuznetskian basin

The lithologic-palaeontologic analysis of the thick (1700 meters) Ilyinskaya section of the Kuznetskycoal basin has been done. In this article it is suggested that the lower boundary of the Ilyinskaya sub-series should be on the bottom ofthe medium sandstone, which is situated in the basement of the section in Mitino village and along the Tom River. This stratum includespolymictic conglomerates and is characterized by a maximum number of stable components (fragments of quartz and siliceous rocks).On this level because of weathering the clarification and kaolinization of the sedimentary rocks are observed. Besides on this level coalfreeKuznetsky deposits are changed by the coal-bearing Ilyinskaya deposits. On the sandstone described above there are argillousrocks, which can be accepted as the basal stratum for the Ilyinskay deposits. In this stratum the mass distribution of big (to 57 mm)bivalves is observed. According to the main bivalve composition this oryctocoenosis is named by P.A. Tokareva as Palaeanodonta-Paleomutella layer. The general quantity and size of the bivalve shells decrease to the section top. New taxons of cordaitalessimultaneously appear with the mass of Paleanodonta and Paleomutella. The high rank of changing of the aquatic and terrestrialorganisms, i.e. bivalves and plants, is underlined by evidence, that it occurred at the same level. The boundary between the Kuznetskyand Ilyinskaya sub-series, which the authors of the article substantiate, lies 182 meters lower in comparison with the regionalstratigraphic scheme. The upper boundary of the Ilyinskaya sub-series is commonly accepted to be on the level of coal bed 38 in thestratotype section. But this level does not reflect any remarkable changing in the sedimentation and biota development. According to theposition of rhythmicity coal bed 38 is situated in the central part of the integrated rhythm. If to connect the situation of the boundarybetween the Ilyinskaya and Yerunakovskaya sub-series with this rhythm it would be more natural to take coal bed 32, which lies in thebasement of the rhythm and is situated 80-90 meters lower. The most expressive boundary inside the Ilyinskaya subseries is coal bed378 according to E.V. Yevtushenkos numeration. This bed is presented by sandstone with frequent pebble. The bed capacity comes to7 meters. Changing of small rhythmicity (in the lower part) into the big one (in the upper part) takes place on this level. Above this layerthere are numerous shells of bivalvs in the basal argillaceous strata. Shells of Paleonodonta are frequently developed in the lower partand they are practically absent in the upper part. The lower part corresponds to the Kazankovo-Markinskaya suite and the upper part - tothe Uskatskaya one. The boundary between them (coal bed 378), as suggested by the authors, is situated 215 meters lower than coal bed4, which is officially accepted as the boundary in the regional stratigraphic scheme of the Kuznetsky coal basin.

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