Kasimovian stage in the Moleben-Iz section (Ilych River, Northern Urals)

Research subject. This study is devoted to the Moleben-Iz section on the Ilych River (Northern Urals) composed of Upper Moscovian (Myachkovian horizon) and Kasimovian rocks.

Material and methods. The composition of rock and fossil inclusions in 49 samples was investigated.

Results. The upper part of the Moscovian is represented by an alteration of bioclastic grainstones and packstones with rare interlayers of dolostones and cherts. Microcodium structures were found in three layers, which is indicative of three episodes of sub-aerial exposure. The Kasimovian lower boundary, which coincides with that of the Upper Carboniferous, is outlined by the appearance of diverse fusulinids of the usvaella genus, as well as by the first  appearance of Eowariengella, Dagmarella, and Kanmeraia genera, since Pulchrellinae representatives dominate across this stratigraphic interval in northern-eastern sections of the European part of Russia, as well as in Canada and USA. At the base of the Kasimovian stage, the authors distinguished the Kanmeraia ozawai – Usvaella usvae biozone as being most consistent with the fauna composition. The Kasimovian is represented by the deposits of the Orlovskian and Kerzhakovian horizons. The deposits of the Orlovskian horizon are composed, in its lower part, by alternating grainstones and packstones, and, in its upper part, by boundstones and lime mudstones. Two levels of the development of biohermal rocks were established, representing two phases of organic buildup formation. The middle part of the Kasimovian (Montiparus montiparus zone) in the studied section was not established, which is likely to have resulted from a break in sedimentation. Upper Kasimovian deposits (Kerzhakovian horizon) are represented by highly silicified bryozoans packstones. These rocks serve as an excellent marking horizon, which is typical of the Northern Urals and partly of the Chernyshev Ridge.

Conclusion. The Moleben-Iz section represents a range of biologic and geologic events, out of which the appearance of new Pulchrellinae genera and a marking horizon at the base of Kerzhakovian horizon are the most notable events.  

1. Antoshkina A.I. (2014) Palaeomicrocodium: A new View on its Origin. Palaeontol. J., 48(4), 353-368. (In Russian)

2. Antoshkina A.I., Saldin V.A., Sandula A.N., Nikulova N.Yu., Ponomarenko E.S., Shadrin A.N., Shebolkin D.N., Kaneva N.A. (2011) Paleozoiskoe osadkonakoplenie na vneshnei zone shel’ fa passivnoi okrainy severo-vostoka Evropeiskoi platformy [Paleozoic sedimentation on the shelf outer zone oh the passive margin at north-east Evropean Platformi]. Syktyvkar, Geoprint Publ., 200 p. (In Russian)

3. Chermnykh V.A. (1976) Stratigrafiya karbona severa urala [Stratigraphy of Carboniferous of the northern part of the Urals]. Leningrad, Nauka Publ., 304 p. (In Russian)

4. Dunham J.R. (1962) Classification of carbonat rocks according to depositional texture. Classification of Carbonat Rocks. Vem. Amer. Assoc. Petrol. Geol., 108-121.

5. Eliseev A.I. (1963) Stratigrafiya i litologiya kamennougol’nykh otlozhenii gryady Chernysheva [Stratigraphy and Lithology of Carboniferous deposits of the Chernyshev Ridge]. Moscow. Leningrad, USSR Academy of Science Publ., 173 p. (In Russian)

6. Eliseev A.I., Mikhailova Z.P. (1962) New dates about Upper Carboniferous of the Chernyshev Ridge. Dokl. Akad. Nauk SSSR, 145(3), 631-634. (In Russian)

7. Ivanova R.M. (1997) Biostratigraphy and systematic of Carboniferous-Permian Fusulinellida of the Urals. Biostratigrafiya i mikroorganizmy fanerozoya Evrazii. Tr. XII Vseross. mikropaleontol. soveshch. [Phanerozoic Biostratigraphy and Microorganisms of the Eurasia. Proc. XII All-Russian Micropaleontologic Conf.]. Moscow, GEOS Publ., 22-28. (In Russian)

8. Ivanova R.M. (2007) Zonal stratigraphy and paleogeography elements of Middle Carboniferous of the Urals respect to Fusulinids and Algaes. Verkhnii paleozoi Rossii: stratigraphiya i paleogeographiya. Mat-ly Vseross. konf. [Upper Palaeozoic of Russia: Stratigraphy and Paleogeography. Materials of the All-Russian conference]. Kazan’, Kazanskii St. Univ. Publ., 123-127. (In Russian)

9. Ivanova R.M. (2008) Fuzulinidy i vodorosli srednego karbona urala (zonal’naya stratigraphiya, paleobiogeographiya, paleontologiya [Fusulinids and Algaes of Middle Carboniferous of the Urals (zonal stratigraphy, palaeobiogeography, palaeontology)]. Ekaterinburg, UB RAS, 204 p. (In Russian)

10. Kabanov P.B. (2003) The Upper Moscovian and Basal Kasimovian (Pennsylvanian) of Central European Russia: Facies, Subaeral Exposures and Depositional Model. Facies, 49, 243-270.

11. Kabanov P.B., Anadon P., Krumbein W.E. (2008) Microcodium: An extensive review and a proposed non-rhizogeniv biologically induced origin for its formation. sediment. Geol., 205 (3-4), 79-99.

12. Kaneva N.A. (2010) Palaeoecology and facies of organic buildups of Upper Carboniferous of north of the Urals (by the example skeletal mounds of the Shchuger River). Vestn. Inst. Geol. Komi SC uB RAS, (7), 2-5. (In Russian)

13. Konovalova M.V. (1991) Stratigraphiya i fusulinidy verkhnego karbona i nizhnei permi Timano-Pechorskoi neftegazonosnoi provintsii [Stratigraphy and Fusulinids of Upper Carboniferous and Lower Permian of the TimanPechora oil-and-gas province]. Moscow, Nedra Publ., 201 p. (In Russian)

14. Mikhailova Z.P. (1974) Fuzulinidy verkhnego karbona Pechorskogo Priural’ya [Fusulinids of Upper Carboniferous of the Pechorian Cisurals]. Leningrad, Nauka Publ., 136 p. (In Russian)

15. Mizens G.A., Badida L.V., Stepanova T.I., Kucheva N.A. (2016). Ancient karst at the eastern slope of the Middle Urals and the Early-Middle Carboniferous boundary. Litosferа, (6), 59-69. (In Russian)

16. Ponomarenko E.S. (2015) Verkhekamennougol’nye-nizhnepermskie karbonatnye otlozheniya zapadnogo sklona Severnogo urala [Upper Carboniferous-Lower Permian carbonate deposits of western slope oh the Northern Urals]. Syktyvkar, Geoprint Publ., 177 p. (In Russian)

17. Ponomarenko E.S. Isakova T.N. (2011) Buzgal’skij Kamen’ section – the key section of Upper Carboniferous–Lower Permian deposits of the Northern Urals: Lithologic and Microfaunistic characteristics. Permskaya sistema: stratigraphiya, paleontologiya, geodinamika i mineral’nye resursy. Mat-ly Mezhdunar. conf. [Permian system: stratigraphy, palaeontology, palaeogeography, geodynamics and mineral resources. Contributions to International conference]. Perm’, Perm. St. Univ. Publ., 173-177. (In Russian)

18. Ponomarenko E.S., Ivanova R.M. (2013) An influence of Anchicodiaceae algae on specificity of palaeocommunities in Lower Permian skeletal mounds of the Northern Urals. Vodorosli v evolutsii biosphery. Mat-ly I paleoalgologicheskoi konferentsii [Algae in Biosphere Evolution. Contributions to the I Palaeoalgological Conference]. Moscow, PIN RAS, 103-104. (In Russian)

19. Ponomarenko E.S., Remizova S.T. (2013) Establishing the Moskovian-Kasimovian boundary in the Northern Urals (the Ilych River). Newslett. Carbonifer. Stratigr., 30, 53-55.

20. Ponomarenko E.S., Remizova S.T., Kamaletdinova L.N. (2009) The problem of stratification of Kasimovian on the Ilych River. Verkhnii paleozoi Rossii: stratigraphiya i fatsial’nyi analiz. Mat-ly II Vseross. konf. [Upper Paleozoic of Russia: Stratigraphy and facial analysis. Contribution to II All-Russian conference]. Kazan’, Kazan. St. Univ. Publ., 147-148. (In Russian)

21. Remizova S.T. (2004) Fuzulinoidy Timana: evolutsiya, biostratigraphiya i paleobiogeographiya [Fusulinoids of the Timan: evolution, biostratigraphy and palaeobiogeography]. Ekaterinburg, UB RAS, 218 p. (In Russian)

22. Remizova S.T. (2015) Middle Carboniferous algal buildups of Timan as indicator of paleoecological conditions. Geologiya rifov. Mat-ly Vseross. Litol. Soveshch. [Geology of Reefs. Proc. All-Russian Lithol. Meeting]. Syktyvkar, IG Komi SC UB RAS, 130-131. (In Russian)

23. Saldin V.A., Remizova S.T. (2015) The Upper Paleozoic organic buildup in the Kos’yu River (Subpolar Urals). Geologiya rifov. Mat-ly Vseross. Litol. Soveshch. [Geology of Reefs. Proc. All-Russian Lithol. Meeting]. Syktyvkar, IG Komi SC UB RAS, 133-135. (In Russian)

24. Sandula A.N. (2009) Upper Moskovian-Kasimovian skeletal mounds on Shchuger River. Vestn. Inst. Geol. Komi SC urO RAN, (9), 2-4. (In Russian)

25. Solov’eva M.N. (1984) The lower boundary of Upper Carboniferous respect to foraminifera faunas of the Yugor Peninsula. Verkhnii karbon SSSR [Upper Carboniferous of USSR]. Moscow, Nauka Publ., 121-158. (In Russian)

26. Varsanof’eva V.A. (1940) Geologic construction of Pechora-Ilych national reserve. Tr. Pechoro-Ilychskogo gos. zapovednika [Works of Pechora-Ilych national reserve], 1, 1-214. (In Russian)

27. Varsanofieva V.A., Rauser-Chernousova D.M. (1960) To characterization of Middle Carboniferous deposits of Ilych River. Sbornik trudov po geologii i paleontologii [Collection of works regarding Geology and Paleontology]. Syktyvkar, 94-126. (In Russian)

28. Yudin V.V. (1994) Orogenez Severa urala i Pai-Khoya [Orogenesis of north of the Urals and Pay-Khoy]. Ekaterinburg, UIF Nauka Publ., 285 p. (In Russian)