Composition, structure, formation environment of the Yaptikshor deposits of the Shezhim facies complex (Upper Katian, Ilych River, Northern Urals)

Research subject. The section of the Upper Katian deposits of the Shezhim facies complex, exposed on the Bol’shaya Kos’yu River (a right tributary of the Ilych River, Northern Urals), exhibits a total thickness of 42.3 metres. The factual material is represented by a collection of more than 60 rock samples, 100 thin sections, and 10 slabs.

Aim. Reconstruction of the sedimentation conditions of the Upper Katian deposits of the Shezhym facies complex.

Methods. Standard lithological and paleontological methods of studying the section were used to dissect the section. Sampling was carried out after no more than 1 m. The sections were studied by the classical optical microscopic method.

Results. The Upper Katian deposits are characterized by numerous remnants of conodont and shell fauna, including the zonal brachiopod species Proconchidium cf. muensteri (St. Joseph), exhibiting a highly heterogeneous lithological composition. At the base, there lies a pack of bioclastic algal-crinoid limestones, which are replaced with tectonic contact by limestone mixed-grained sandstones and limestone block breccias upward the section. Above, they overlap with layered bioclastic limestones with numerous fauna typical of this age range and widespread within the Timan-North Ural region.

Conclusions. According to the stratigraphic position and faunal characteristics, the Upper Katian deposits are reliably correlated with the stratotype of the Yaptikshor formation of the Subpolar Urals. Established on the basis of studying a variety of sections of the Northern, Subpolar, Polar Urals, and Chernyshev Ridge, the transformation of the outer margin of the Pechora Plate from rimmed platform in the Middle Katian to an open platform and to a ramp in the Late Katian (Yaptikshor Time) can also be traced in the section on the Bol’shaya Kos’yu River. The deposits characterize the shift of sedimentation conditions from shallow to deeper ones, which corresponds to the transgressive stage of the sedimentary basin development. The section on the Kosyu River differs from the stratotype of the Yaptikshor Formation by the significant presence of lithoclastic limestone differences, which were most likely formed as a result of the manifestation of tectonic activity of the Pechora Plate. This fact reflects the regional features of the North Ural margin of the carbonate platform, due to its block structure and different intensity of tectonic processes.

1. Antoshkina A.I. (1994) Reefs in the Paleozoic of the Pechora Urals. St.Petersburg, Nauka Publ., 154 p. (In Russ.)

2. Antoshkina A.I. (2003) Reef formation in the Paleozoic (North of the Urals and adjacent regions). Ekaterinburg, UrO RAN, 304 p. (In Russ.)

3. Antoshkina A.I. (2011a) Early Paleozoic reef formation in the North of the Urals as an example of its relationship with geobiospheric changes. Reef formations and reefs in the evolution of the biosphere. (Ed. by S.V. Rozhnov). Moscow, PIN RAN, 116-141. (In Russ.)

4. Antoshkina A.I. (2011б) Genetic types of carbonate psephitolites of that Lower Paleozoic of the North of the Urals. II. Types, models and features of formation. Lithosphere (Russia), (3), 39-49. (In Russ.)

5. Antoshkina A.I. (2015) Features of the Hirnant sedimentation in the North Ural region. The evolution of sedimentary processes in the history of the Earth: materials of the VIII All-Russian Lithological Meeting. Moscow, RGU nefti i gaza im. I.M. Gubkina, 53-56. (In Russ.)

6. Antoshkina A.I., Shmeleva L.A. (2018) Pecularities of composition, structure and environments of Hirnantian deposits in the Timan-Northern Ural sedimentary basin. Lithosphere (Russia), 18(4), 543-565. (In Russ.) https://doi.org/10.24930/1681-9004-2018-18-4-543-565

7. Antoshkina A.I., Afanasyev A.K., Beznosova T.M. (1989) A new stratigraphic scheme of the Upper Ordovician and Silurian of the Northern Urals (Yelets zone). Syktyvkar, Komi NTs UrO AN SSSR, 16 p. (In Russ.)

8. Antoshkina A.I., Ponomarenko E.S., Silaev V.I. (2017) Biochemogenic origin of the ordovician chamosite in the Northern Urals. Vestn. IG Komi NTS URO RAN, (9), 12-22. (In Russ.)

9. Antoshkina A.I., Saldin V.A., Sandula A.N., Nikulova N. Yu., Ponomarenko E.S., Shebolkin D.N., Shadrin A.N., Kaneva N.A. (2011) Paleozoic sedimentation in the outer shelf zone of the passive continental margin of the northeastern European Platform. Syktyvkar, Geoprint Publ., 200 p. (In Russ.)

10. Bathurst R.G.C. (1959) Diagenesis in Mississippian calcilutites and pseudobreccias. J. Sed. Petrol., 29, 365-376.

11. Batten Hender K.L., Dix G.R. (2008) Facies development of a Late Ordovician mixed carbonate siliciclastic ramp proximal to the developing Taconic orogen: Lourdes Formation, Newfoundland, Canada. Facies, 54, 121-149.

12. Bergström S.M., Leslie S.A. (2009) The Ordovician conodont Amorphognathus ordovicicus Branson and Mehl and the evolution of Amorphognathus Branson and Mehl, a key genus in Ordovician conodont biostratigraphy. International Conodont Symposium (ICOS 2009) Abstracts. (Ed. by C.M. Henderson, C. MacLean). Newsletter of the Subcommission on Permian Stratigraphy, (53-1), 6-7.

13. Beznosova T.M., Maidl T.V., Myannik P., Marta T. (2011) The border of the Ordovician and Silurian on the western slope of the Circumpolar Urals. Stratigr. Geol. Korrel., 19(4), 21-39. (In Russ.)

14. Blount D.N., Moore C.H. (1969) Depositional and non-depositional carbonate breccias, Chiantla Quadrangle, Guatemala. Geol. Soc. Amer. Bull., 80, 429-442.

15. Brachert T., Dullo C. (1990) Correlation of deep-sea sediments and fore reef carbonates in the Red Sea: an important clue for basin analysis. Mar. Geol., 92, 255-267.

16. Cyclic and Event Stratification (1982). (Ed. by G. Einsele, A. Seilacher). Berlin, Heidelberg; New York, SpringerVerlag, 536 p.

17. Dembovsky B.Ya., Dembovskaya Z.P. (1992) Report on the object: “Production of experimental and methodological work on the dismemberment of the Lower Paleozoic sections of the western slope of the Northern Urals (Shchugoro-Uninsky district)” for 1989-1992. Vorkuta, 218 p. (In Russ.)

18. Dembovsky B.Ya., Dembovskaya Z.P., Klyuzhina M.L., Nasedkina V.A. (1990) Ordovician of the Circumpolar Urals. Geology, lithology, stratigraphy. Sverdlovsk, UrO AN SSSR, 210 p. (In Russ.)

19. Dunham R.J. (1962) Classification of Carbonate rocks according to depositional texture. Classification of Carbonate Rocks. (Ed. by W.E. Ham). Tulsa, AAPG, 108-121.

20. Enos P., Moore C.H. (1983) Fore-reef slope environment. Carbonate Depositional Environments. (Ed. by P.A. Scholle, D.G. Bebout, C.H. Moore). Tulsa, American Association of Petroleum Geologists, 33, 507-537.

21. Flügel E. (2010) Microfacies of carbonate rocks: analysis, interpretation and application. Berlin; Heidelberg, Springer Verlag, 976 p.

22. Folk R.L. (1959) Practical petrographic classification of limestones. Amer. Assoc. Petrol. Geol. Bull., 43, 1-38.

23. Füchtbauer H., Richter D.K. (1983a) Carbonate internal breccias: A source of mass flow at early geosynclinal platform margins in Greece. Soc. Econ. Paleont. Min. Spec. Publ., 33, 207-215.

24. Füchtbauer H., Richter D.K. (1983b) Relations between submarine fissures, internal breccias and mass flow during Triassic and earlier rifting periods. Geol. Rundschau, 72, 53-66.

25. Gradstein F.M., Ogg J.G., Schmitz M.D., Ogg G.M. (2012) The Geologic Time Scale. 2 vols. Amsterdam, Elsevier Science Ltd., 1177 p.

26. Gradstein F.M., Ogg J.G., Smith A.G. (2004) Geologic Time Scale. Episodes, 27(2), 83-100. https://doi.org/10.18814/epiiugs/2004/v27i2/002

27. Hvorova I.V. (1958) Atlas of carbonate rocks of the middle and upper carboniferous of the Russian platform. Moscow, AN SSSR, 167 p. (In Russ.)

28. Iordanskij N.N. (1928) New data on the distribution of the Lower Silurian in the Upper Pechora basin. Izv. Assotsiatsii NII pri fiz.-mat. fak. 1-go MGU, 1(1-2), 74-96. (In Russ.)

29. James N.P., Jones B.G. (2015) Origin of carbonate sedimentary rocks. Hoboken, Wiley, 464 p.

30. Kaljo D., Männik P., Martma T., Nõlvak J. (2012) More about the Ordovician. Silurian transition beds at Mirny Creek, Omulev Mountains, NE Russia: carbon isotopes and conodonts. Estonian J. Earth Sci., 61(4), 277-294.

31. Klyuzhina M.L. (1985) Paleogeography of the Urals in the Ordovician period. Moscow, Nauka Publ., 189 p. (In Russ.)

32. Kondiain A.G. (1967) Silurian and Lower Devonian deposits of the Belsko-Yelets facies zone of the Pechora Urals. Tr. VSEGEI, 144, 87-123. (In Russ.)

33. Kondiajn O.A. (1960) Structural features of the Pechora Urals. Materials of the annual session of the Academic Council of VSEGEI on the results of the work of 1958. Leningrad, Nedra Publ., 96-98. (In Russ.)

34. Logan B.W., Semeniuk V. (1976) Dynamic metamorphism; Processes and products in Devonian carbonate rocks, Canning Basin, Western Australia. Geol. Soc. Australia, Spec. Publ., 6, 1-138.

35. Lokier S.W., Al Junaibi M. (2016) The petrographic description of carbonate facies: Are we all speaking the same language? Sedimentology, 63(7), 1843-1885. https://doi.org/10.1111/sed.12293

36. Malyshev N.A. (2002) Tectonics, evolution and oil and gas content of sedimentary basins of the European north of Russia. Ekaterinburg, UrO RAN, 270 p. (In Russ.)

37. Mavrinskaya T.M., Yakupov R.R. (2016). Ordovician deposits of the western slope of the Southern Urals and their correlation by conodonts and chitinozoa. Geologiya i Geofizika, 57(2), 333-352. (In Russ.)

38. Melnikov S.V. (1999) Ordovician and Silurian conodonts of the Timan-North Ural region. St.Petersburg, VSEGEI, 135 p. (In Russ.)

39. Norton W.H. (1917) A classification of breccias. J. Geol., 25, 160-194.

40. Obrador A., Pomar L., Taberner C. (1992) Late Miocenebreccia of Menorca (Balearic Islands): a basis for the interpretation of a Neogene ramp deposit. Sediment. Geol., 79, 203-223.

41. Pershina A.I. (1962) Boundary layers of the Ordovician and Silurian in the Pechora Urals. Tr. IG Komi filiala AN SSSR, vyp. 3, 28-37. (In Russ.)

42. Pomoni-Papaioannou F., Dornsiepen U. (1987) Post-Pliocene calichified solution-collapse breccia from Eastern Crete, Greece. Facies, 18, 169-180.

43. Ponomarenko E.S. (2020) Structure and conditions of formation of the Upper Lochkovian Valgan formation (Lower Devon, Ilych River, Northern Urals). Lithosphere (Russia), 20(1), 63-75. (In Russ.)

44. Ponomarenko E.S. (2021) Lithological and isotopic (δ13C, δ18O) features of the Upper Silurian deposits of the zarif lagoon of the Ilych river basin (Northern Urals). Vestn. Geonauk, 11(323), 43-54. (In Russ.) https://doi.org/10.19110/geov.2021.11.4

45. Ponomarenko E.S. (2022) Lower Ludford (Upper Silurian) slope deposits in the Lyagadin section (Ilych River, Northern Urals). Lithosphere (Russia), 22(1), 75-100. (In Russ.) https://doi.org/10.24930/1681-9004-2022-22-1-75-100

46. Ponomarenko E.S., Nikulova N.Yu. (2020) Lithological and geochemical features of Upper Emsian (Lower Devonian) carbonate-clay deposits on the Ilych River (Northern Urals). Vestn. Geonauk, 8(308), 10-17. (In Russ.)

47. Productive forces of the Komi ASSR (1953). V. 1. Geological structure and minerals. Moscow, AN SSSR, 464 p. (In Russ.)

48. Rasskazova N.V. (1988) Correlation of productive horizons of the Upper Ordovician-Lower Devonian. Stratigraphy and lithology of oil and gas deposits of the TimanPechora province. (Ed. by V.I. Bogatskiy). Leningrad, VNIGRI, 30-36. (In Russ.)

49. Richter D.K., Füchtbauer H. (1981) Merkmale und Genese von Breccien und ihre Bedeutung im Mesozoikum von Hydra (Griechenland). Z. Deutsch. Geol. Ges., 132, 451-501.

50. Sandula A.N. (2008) Limestone breccias in carboniferous deposits of the Pechora Urals. Ekaterinburg, UrO RAN, 144 p. (In Russ.)

51. Shmeleva L.A. (2015) Composition and structure of the Upper Katian sediments (basin of the Ilych, Northern Urals). The evolution of sedimentary processes in the history of the Earth: materials of the VIII All-Russian Lithological Meeting. V. 2. Moscow, RGU nefti i gaza im. I.M. Gubkina, 473-475. (In Russ.)

52. Shmeleva L.A. (2018) Paragenetic rock associations as a reflexion of carbonate platform margin lithogeodinamic evolution in the Late Ordovician (Ilych River basin, Northern Urals). Vestn. IG Komi NTs UrO RAN, (5), 3-12. (In Russ.)

53. Shmeleva L.A. (2020) The Upper Ordovician reef Bol’shaya Kos’yu, Ilych River, Northern Urals (structure, paleobiocenosis, microfacies, model of formation). Lithosphere (Russia), 20(4), 557-572. (In Russ.). https://doi.org/10.24930/1681-9004-2020-20-4-557-572

54. Shmeleva L.A. (2024) Upper Ordovician-Lower Silurian deposits in the Zakola section (Ilych River, Northern Urals) – composition, structure, environments of formation. Lithosphere (Russia), 24(1), 98-114. (In Russ.) https://doi.org/10.24930/1681-9004-2024-24-1-98-114

55. Shmeleva L.A., Ponomarenko E.S. (2023) Some details of the structure of the northern centricline of the Kos’yu-Un’ya syncline (Ilych River, Northern Urals). Vestn. Geonauk, 11(347), 48-58. (In Russ.). https://doi.org/10.19110/geov.2023.11.5

56. Shmeleva L.A., Tolmacheva T.Yu. (2016) Carbonate deposits of the Upper Ordovician on the Bolshaya Kosyu River (Northern Urals): sequence characteristic and the first data on conodonts. Region. Geologiya i Metallogeniya, 65, 50-59. (In Russ.)

57. Shvecov M.S. (1948) Petrography of sedimentary rocks. Moscow; Leningrad, Gosgeolizdat, 431 p. (In Russ.)

58. Stanton R.J. (1966) The solution brecciation process. Geol. Soc. Amer. Bull., 77, 843-848.

59. Stratigraphic schemes of the Urals (Precambrian, Paleozoic) (1993). (Ed. by N.Ya. Antsygin, B.A. Popov, B.I. Chuvashov). Ekaterinburg, IGG UrO RAN, 152 p. (In Russ.)

60. Supporting sections of the Upper Ordovician and Lower Silurian of the Circumpolar Urals (1987) (Comp. by V.S. Tsyganko, V.A. Chermnykh). Syktyvkar, Komi filial AN SSSR, 94 p. (In Russ.)

61. Teodorovich G.I. (1958) Autigenic minerals of sedimentary rocks. Moscow, AN SSSR, 231 p. (In Russ.)

62. The state of knowledge of the stratigraphy of the Precambrian and Phanerozoic of Russia. Tasks of further research (2008). Resolutions of the Interdepartmental Stratigraphic Committee and its permanent commissions, vyp. 38. (Ed. by A.I. Zhamoida, O.V. Petrov). St.Petersburg, VSEGEI, 131 p. (In Russ.)

63. Timonin N.I. (1998) Pechora plate: the history of geological development in the Phanerozoic. Ekaterinburg, UrO RAN, 240 p. (In Russ.)

64. Yudin V.V. (1983) Variscids of the Northern Urals. Leningrad, Nauka Publ., 174 p. (In Russ.)

65. Yudin V.V. (1994) Orogeny of the North of the Urals and Pai Khoi. Ekaterinburg, Nauka Publ., 286 p. (In Russ.)

66. Zhemchugova V.A., Melnikov S.V., Danilov V.N. (2001) The Lower Paleozoic of the Pechora oil and gas basin (structure, conditions of formation, oil and gas content). Moscow, Akademiya gornykh nauk, 110 p. (In Russ.).