Biofacies of Black Shale Source Rocks from the Kama–Kinel Trough System (Volga–Ural Petroleum Province) across the Devonian–Carboniferous Boundary: Characteristics, Sedimentation Rates, and Depositional Scenarios

Organic-rich Devonian–Carboniferous deposits from the axial and marginal zones of the Kama–Kinel Trough System were investigated. Conodont data place the upper Famennian interval in the expansa Zone and the lower Tournaisian interval in the duplicata and quadruplicata Zones. Six biofacies were identified, described and illustrated, representing anoxic, dysoxic and relatively oxygenated settings. These biofacies differ in organic-matter content, the abundance and diversity of skeletal remains, the character of microbial buildups, and rock textures, including ichnotextures. The studied sections show frequent alternations of biofacies, from metre-scale to centimetre-scale intervals, with the finest alternation recorded on the trough slope. Three depositional scenarios are proposed, corresponding to three basin states: a fully anoxic basin affected by hydrogen sulphide, a stratified basin with separate oxic and anoxic water layers, and a basin with relatively high oxygen content throughout the water column.

1. Afanasieva M.S., Kononova L.I., Zaytseva E.L., Baranova A.V. (2023). Lower Tournaisian (Lower Carboniferous) microfauna of the Volga–Ural Basin (Russia). Paleontological Journal, 57(1), pp. 1–30. https://doi.org/10.1134/S0031030123600208

2. Akhmadishin F.F., Lvova I.V., Karimov M.F., Mironov D.A., Khalikova D.A., Askarov R.F. (2023). Method for stabilization of borehole walls using alkali metal silicates. Neftyanoe khozyaystvo = Oil industry, 9, pp. 34–37. (In Russ.) https://doi.org/10.24887/0028-2448-2023-9-34-37

3. Alekseev A.S., Nikolaeva S.V., Goreva N.V., Donova N.B., Kossovaya O.L., Kulagina E.I., Kucheva N.A., Kurilenko A.V., Kutygin R.V., Popeko L.I., Stepanova T.I. (2022). Russian regional Carboniferous stratigraphy. Geological Society London, Special Publications, 512(1), pp. 49–117. https://doi.org/10.1144/SP512-2021-134

4. Alekseev V.P. (2014). Atlas of subaqueous facies of Lower Cretaceous deposits of Western Siberia (KhMAO–Ugra). Ekaterinburg: Ural State Mining University, 284 p. (In Russ.)

5. Alekseev V.P. (2019). Oil and gas lithology: textbook. Ekaterinburg: Ural State Mining University, 576 p. (In Russ.)

6. Allison P.A., Wignall P.B., Brett C.E. (1995). Paleo-oxygenation: effects and recognition. Marine Palaeoenvironmental Analysis from Fossils. Eds. D.W.J. Bosence, P.A. Allison. Geological Society London, Special Publications, 83(1), pp. 97–112. https://doi.org/10.1144/GSL.SP.1995.083.01.06

7. Amon E.O. (2011). Paleontology of microfossils (micropaleontology): textbook. Ekaterinburg: Ural State Mining University, 520 p. (In Russ.)

8. Aver’yanov V.I. (1960). Conditions of formation of the Sarailinskaya strata of Tataria. Geologiya nefti, 2, pp. 25–28. (In Russ.)

9. Becker R.T., Marshall J.E.A., Da Silva A.-C., Agterberg F.P., Gradstein F.M., Ogg J.G. (2020). The Devonian Period. Geologic Time Scale 2020. Eds. J.M. Gradstein, J.G. Ogg, M.D. Schmitz, G.M. Ogg. Amsterdam: Elsevier, pp. 733–810. https://doi.org/10.1016/B978-0-12-824360-2.00022-X

10. Bosak T., Greene S.E., Newman D.K. (2007). A likely role for anoxygenic photosynthetic microbes in the formation of ancient stromatolites. Geobiology, 5(2), pp. 119–126. https://doi.org/10.1111/j.1472-4669.2007.00104.x

11. Buatois L., Mangano M.G. (2011). Ichnology. Organism-Substrate Interaction in Space and Time. Cambridge University Press, Cambridge. https://doi.org/10.1017/CBO9780511975622

12. Bumagina V.A., Martynyuk E.V., Chertina K.N. (2024). Microbiolite finds in the Bazhenov formation. Ekspozitsiya Neft’ Gaz, 7, pp. 20–24. (In Russ.) https://doi.org/10.24412/2076-6785-2024-7-20-24

13. Chupakhina V.V., Korobova N.I., Kalmykov G.A., Zavyalova A.P., Karpushin M.Yu., Radchenko K.A. (2022). Different types of void space and quality of unconventional reservoirs in the Upper Devonian domanic high-carbon deposits of Mukhanovo-Erokhovsky trough (Volga-Ural basin. Georesursy = Georesources, 24(2), pp. 139–149. (In Russ.) https://doi.org/10.18599/grs.2022.2.14

14. Croizé D., Renard F., Gratier J.-P. (2013). Compaction and porosity reduction. Carbonates: A Review of Observations, Theory, and Experiments. Advances in Geophysics, 54. Ed. R. Dmowska. Elsevier, Amsterdam, pp. 181–238. https://doi.org/10.1016/B978-0-12-380940-7.00003-2

15. De Vleeschouwer D., Rakocinski M., Racki G., Bond D.P.G., Sobień K., Claeys P. (2013). The astronomical rhythm of Late Devonian climate change (Kowala section, Holy Cross Mountains, Poland). Earth and Planetary Science Letters, 365, pp. 25–37. https://doi.org/10.1016/j.epsl.2013.01.016

16. Emeis K.C., Sakamoto T., Wehausen R., Brumsack H.-J. (2000a). The sapropel record of the eastern Mediterranean Sea—results of Ocean Drilling Program Leg 160. Palaeogeography, Palaeoclimatology, Palaeoecology, 158(3–4), pp. 371–395. https://doi.org/10.1016/S0031-0182(00)00059-6

17. Emeis K.C., Struck U., Schulz H.-M., Rosenberg R., Bernasconi S., Erlenkeuser H., Sakamoto T., Martinez-Ruiz F. (2000b). Temperature and salinity variations of Mediterranean Sea surface waters over the last 16,000 years from records of planktonic stable oxygen isotopes and alkenone unsaturation ratios. Palaeogeography, Palaeoclimatology, Palaeoecology, 158(3–4), pp. 259–280. https://doi.org/10.1016/S0031-0182(00)00053-5

18. Emeis K.C., Whelan J.K., Tarafa M. (1991). Sedimentary and geochemical expressions of oxic and anoxic conditions on the Peru Shelf. Modern and Ancient Continental Shelf Anoxia. Eds. R.V. Tyson, T.H. Pearson. Geological Society London, Special Publications, 58, pp. 155–170. https://doi.org/10.1144/GSL.SP.1991.058.01.11

19. Ferri F., McMechan M., Richards B., Friedman R. (2021). Organic Rich Upper Devonian Shales of the Patry and Exshaw Formations (Besa River Group) in the Subsurface of Liard Basin. British Columbia Geological Survey Paper, 42 p.

20. Flügel E. (2010). Microfacies of Carbonate Rocks, Analysis, Interpretation and Application. Springer-Verlag, Berlin, 996 p.

21. Fortunatova N.K., Zaitseva E.L., Bushueva M.A., Ermolova T.E., Mikheeva A.I., Stupak A.A., Baranova A.V., Kononova L.I., Mamontov D.A., Kharchenko S.I., Avdeeva A.A., Kanev A.S., Evdokimov N.V., Shishkina T.Yu., Volodina A.G., Kholmyanskaya N.Yu., Kravchenko M.S., Afanasyeva M.S., Evdokimova I.O. (2023). Stratigraphy of the Lower Carboniferous of the Volga–Ural subregion (materials for updating the stratigraphic scheme). Moscow: VNIGNI, 288 p. (In Russ.)

22. Fortunatova N.K., Zaitseva E.L., Kononova L.I., Baranova A.V., Bushueva M.A., Mikheeva A.I., Afanasyeva M.S., Obukhovskaya T.G. (2018). Lithological-facies and biostratigraphic characteristics of Upper Devonian deposits in the reference borehole 1 Melekesskaya (Melekess Depression, Volga–Ural region). Byulleten’ Moskovskogo Obshchestva Ispytatelei Prirody. Otdel geologicheskii, 93(5–6), pp. 3–49. (In Russ.)

23. Fossil bacteria and other microorganisms in terrestrial rocks and astromaterials. (2011). Eds. A.Yu. Rozanov, G.T. Ushatinskaya. Moscow: PIN RAN, 172 p. (In Russ.)

24. Geology and petroleum potential of the Kama–Kinel troughs. Ed. V.I. Troepol’skii. Kazan: Kazan University Press, 307 p. (In Russ.)

25. Grachevskii M.M. (1959). Features of the structure and formation of the Kama–Kinel depression in the Kuibyshev Trans-Volga region and Tataria. Doklady Akademii Nauk SSSR, 125(6), pp. 1311–1314. (In Russ.)

26. Gubareva V.S. (2003). Carboniferous system. Geology of Tatarstan: Stratigraphy and tectonics. Ed. B.V. Burov. Moscow: GEOS, pp. 103–124. (In Russ.)

27. Kabanov P.B. (2022). Jura Creek field trip: the drowning unconformity and anoxic sediments at the Devonian–Carboniferous boundary, Alberta. Geological Survey of Canada, Open File 8922.

28. Kabanov P., Gouwy S.A., van der Boon A., Grasby S.E. (2023b). Nature of Devonian anoxic events based on multiproxy records from Panthalassa, NW Canada. Global and Planetary Change, 227, 104176. https://doi.org/10.1016/j.gloplacha.2023.104176

29. Kabanov P., Hauck T.E., Gouwy S.A., Grasby S.E., van der Boon A. (2023a). Oceanic anoxic events, photic-zone euxinia, and controversy of sealevel fluctuations during the Middle–Late Devonian. Earth-Science Reviews, 241, 104415. https://doi.org/10.1016/j.earscirev.2023.104415

30. Kabanov P., Jiang C. (2020). Photic-zone euxinia and anoxic events in a Middle–Late Devonian shelfal sea of Panthalassan continental margin, NW Canada: changing paradigm of Devonian Ocean and sea level fluctuations. Global and Planetary Change, 188, 103153. https://doi.org/10.1016/j.gloplacha.2020.103153

31. Kazmierczak J., Kremer B., Racki G. (2012). Late Devonian marine anoxia challenged by benthic cyanobacterial mats. Geobiology, 10, pp. 371–383. https://doi.org/10.1111/j.1472-4669.2012.00339.x

32. Keogh M.E., Törnqvist T.E., Kolker A.S., Erkens G., Bridgeman J.G. (2021). Organic matter accretion, shallow subsidence, and river delta sustainability. Journal of Geophysical Research: Earth Surface, 126, e2021JF006231. https://doi.org/10.1029/2021JF006231

33. Khachatryan R.O. (1964). Devonian and Carboniferous formations of the eastern Russian Platform. Doklady Akademii Nauk SSSR, 159(6), pp. 1293–1296. (In Russ.)

34. Khachatryan R.O. (1979). Tectonic development and petroleum potential of the Volga–Kama anteclise. Moscow: Nauka Publ., 171 p. (In Russ.)

35. Khachatryan R.O., Mitreikin Yu.B. (1991). Current geological problems of developing oil resources in the Kama–Kinel troughs. Geology and development of oil resources in the Kama–Kinel system of troughs. Ed. N.A. Krylov. Moscow: Nauka Publ., pp. 7–17. (In Russ.)

36. Kleshchev A.I., Kirov V.A., Petropavlovskii V.V. (1957). On the age of the Sarailinskaya terrigenous strata of Tataria. Geologiya nefti, 12, pp. 48–59. (In Russ.)

37. Kleshchev A.I., Petropavlovskii V.V., Kirov V.A. (1959). Some data on the structure of the Sarailinskaya strata of Tataria. Stratigraphy of the lower part of the Lower Carboniferous of the Volga–Ural region of the Russian Platform. Ed. S.V. Semikhatova. Moscow: Gostoptekhizdat, pp. 104–110. (In Russ.)

38. Lee S.-J., Browne K.M., Golubic S. (2000). On stromatolite lamination. Microbial Sediments. Eds. R.E. Riding, S.M. Awramik. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-04036-2_3

39. Littke R., Zieger L. (2020). Formation of organic-rich sediments and sedimentary rocks. Hydrocarbons, Oils and Lipids: Diversity, Origin, Chemistry and Fate. Handbook of Hydrocarbon and Lipid Microbiology. Ed. H. Wilkes. Springer, pp. 476–492. https://doi.org/10.1007/978-3-319-90569-3_14

40. Liu Y.Q., Ji Q., Kuang H.W., Jiang X.J., Xu H., Peng N. (2012). U–Pb zircon age, sedimentary facies, and sequence stratigraphy of the Devonian– Carboniferous boundary, Daposhang section, Guizhou, China. Palaeoworld, 21(2), pp. 100–107. https://doi.org/10.1016/J.PALWOR.2012.03.001

41. Loya Y., Puglise K.A., Bridge T.C.L. (Eds.). (2019). Mesophotic Coral Ecosystems. New York: Springer, 1013 p. https://doi.org/10.1007/978-3-319-92735-0

42. Lozin E.V. (2002). Deep structure and petroleum potential of the Volga–Ural region and adjacent territories. Litosfera, 3, pp. 45–68. (In Russ.)

43. Mata S.A., Bottjer D.J. (2012). Microbes and mass extinctions: paleoenvironmental distribution of microbialites during times of biotic crisis. Geobiology, 10(1), pp. 3–24. https://doi.org/10.1111/j.1472-4669.2011.00305.x

44. Mavrinskaya T.M., Sharipova A.R., Pazukhin V.N. (2023). Conodonts of the Famennian Stage of the Upper Devonian and the Tournaisian Stage of the Lower Carboniferous of the Magnitogorsk ore field. Geologicheskii vestnik, 3, pp. 87–97. (In Russ.) https://doi.org/10.31084/2619-0087/2023-3-8

45. Mirchink M.F., Khachatryan R.O., Gromeka V.I., Mitreikin Yu.B., Mkrtchyan O.M., Nartov G.V. (1965). Tectonics and zones of oil and gas accumulation in the Kama–Kinel system of troughs. Moscow: Nauka Publ., 214 p. (In Russ.)

46. Mirchink M.F., Khachatryan R.O., Mkrtchyan O.M. (1962). Tectonics and origin of the Kama–Kinel system of troughs. Voprosy tektoniki neftenosnykh oblastei. Moscow: USSR Academy of Sciences Press, pp. 86–101. (In Russ.)

47. Mkrtchyan O.M. (1964). Upper Devonian reefs and their role in the formation of oil-bearing structures in the eastern Ural–Volga region. Moscow: Nauka Publ., 117 p. (In Russ.)

48. Mkrtchyan O.M. (1980). Regularities in the distribution of structural forms in the eastern Russian Plate. Moscow: Nauka Publ., 135 p. (In Russ.)

49. Myrow P.M., Ramezani J., Hanson A.E., Bowring S.A., Racki G., Rakociński M. (2014). High-precision U–Pb age and duration of the latest Devonian (Famennian) Hangenberg Event, and its implications. Terra Nova, 26(3), pp. 222–229. https://doi.org/10.1111/ter.12090

50. Nikishin A.M., Ziegler P.A., Stephenson R.A., Cloetingh S.A.P.L., van Hoorn B., Furne A.V., Fokin P.A., Ershov A.V., Bolotov S.N., Korotaev M.V., Alekseev A.S. (1996). Late Precambrian to Triassic history of the East European Craton: dynamics of sedimentary basin evolution. Tectonophysics, 268(1–4), pp. 23–63. https://doi.org/10.1016/S0040-1951(96)00228-4

51. Pazukhin V.N., Kulagina E.I. (2014). Carboniferous stratigraphy of the Zilair synclinorium (South Urals). Byulleten’ Moskovskogo Obshchestva Ispytatelei Prirody. Otdel geologicheskii, 89(6), pp. 19–44. (In Russ.)

52. Plotitsyn A.N., Ponomarenko E.S., Vevel’ Ya.A. (2018). Tournaisian deep-water sequences of the Usa River basin (Polar Urals). Neftegazovaya geologiya. Teoriya i praktika, 13(3), pp. 1–34. (In Russ.) http://www.ngtp.ru/rub/2/32_2018.pdf

53. Pozner V.M. (1955). Stratigraphy of the terrigenous strata of the Lower Carboniferous of the Kama–Kinel depression. Doklady Akademii Nauk SSSR, 104(6), pp. 892–894. (In Russ.)

54. Puchkov V.N. (2010). Geology of the Urals and Cis-Urals (current issues of stratigraphy, tectonics, geodynamics, and metallogeny). Ufa: DizainPoligrafServis, 280 p. (In Russ.)

55. Resolutions of the Interdepartmental Stratigraphic Committee and its standing commissions (2003). Issue 34. St Petersburg: VSEGEI, 46 p. (In Russ.)

56. Rhoads D.C., Mulsow S.G., Gutschick R., Baldwin C.T., Stolz J.F. (1991). The dysaerobic zone revisited: a magnetic facies? Modern and Ancient Continental Shelf Anoxia. Eds. R.V. Tyson, T.H. Pearson. Geological Society London, Special Publications, 58, pp. 1–24. https://doi.org/10.1144/GSL.SP.1991.058.01.01

57. Rohling E.J. (1994). Review and new aspects concerning the formation of eastern Mediterranean sapropels. Marine Geology, 122(1–2), pp. 1–28. https://doi.org/10.1016/0025-3227(94)90202-X

58. Saakyan M.I. (2010). Conditions of occurrence of productive strata in the terrigenous sequence of the Lower Carboniferous on the example of the Arlan field based on automated correlation of well sections. Abstract of PhD thesis. Moscow, 22 p. (In Russ.)

59. Sandberg C.A., Streel M., Scott R.A. (1971). Comparison between conodont zonation and spore assemblages at the Devonian–Carboniferous boundary in the western and central United States and in Europe. 7e Congrès International de Stratigraphie et de Géologie du Carbonifère, Compte Rendu, 1, pp. 179–203.

60. Shinn E.A., Robbin D.M. (1983). Mechanical and chemical compaction in fine-grained shallow-water limestones. Journal of Sedimentary Petrology , 53(2), pp. 595–618. https://doi.org/10.1306/212F8242-2B24-11D7-8648000102C1865D

61. Silantiev V.V., Miftakhutdinova D.N., Nurgalieva N.G. (2024). From Siliciclastics to Carbonates and Black shales: Deciphering Sedimentary Continuity and Discontinuity in the Devonian Landscapes of the Volga-Ural Petroleum Province. Georesursy = Georesources, 26(4), pp. 62–82. https://doi.org/10.18599/grs.2024.4.1

62. Silantiev V.V., Nurgaliev D.K., Sungatullina G.M., Miftakhutdinova D.N., Kulikova A.V., Nourgalieva N.G., Saetgaleeva Ya.Ya., Vandin A.S. (2025). First U–Pb LA-ICP-MS radioisotopic ages of the Devonian– Carboniferous boundary black shales (Domanik facies) in the Kama–Kinel Trough System, Volga–Ural Petroleum Province, East European Platform. Georesursy = Georesources, 27(2), pp. 297–304. https://doi.org/10.18599/grs.2025.2.22

63. Silantiev V.V., Validov M.F., Miftakhutdinova D.N., Morozov V.P., Ganiev B.G., Lutfullin A.A., Shumatbaev K.D., Khabipov R.M., Nurgalieva N.G., Tolokonnikova Z.A., Korolev E.A., Sudakov V.A., Smirnova A.V., Golod K.A., Leontiev A.A., Shamsiev R.R., Noykin M.V., Kosarev V.E., Nikonorova D.A., Akhmetov R.F. (2022). Sedimentation model of the middle Devonian clastic succession of the South Tatar Arch, Pashyian Regional stage, Volga-Ural Oil and Gas Province, Russia. Georesursy = Georesources, 24(4), pp. 12–39. (In Russ.) https://doi.org/10.18599/grs.2022.4.2

64. Silantiev V.V., Validov M.F., Miftakhutdinova D.N., Nourgalieva N.G., Korolev E.A., Ganiev B.G., Lutfullin A.A., Shumatbaev K.D., Khabipov R.M., Sudakov V.A., Akhmadullina Yu.A., Golod K.A., Leontev A.A., Shamsiev R.R., Nikonorova D.A., Krikun S.S., Noykin M.V., Abdullina E.A. (2023). Visean terrigenous sediments of the South Tatar Arch (Volga-Urals oil and gas bearing province) – multifacial filling of the karst surface of the Tournaisian isolated carbonate platform. Georesursy = Georesources, 25(4), pp. 3–28. (In Russ.) https://doi.org/10.18599/grs.2023.4.1

65. Smelkov V.M., Tukhvatullin R.K., Uspenskii B.V. (2007). Petroleum potential of Paleozoic deposits of Tatarstan. Petroleum potential of the Republic of Tatarstan. Geology and development of oil fields. Vol. 1. Ed. R.Kh. Muslimov. Kazan: Fen, pp. 66–75. (In Russ.)

66. Southam J.R., Peterson W.H., Brass G.W. (1982). Dynamics of anoxia. Palaeogeography, Palaeoclimatology, Palaeoecology, 40, pp. 183–198. https://doi.org/10.1016/0031-0182(82)90089-X

67. Staffers P., Degens E.T., Trimonis E.S. (1978). Stratigraphy and suggested ages of Black Sea sediments cored during Leg 42B. Initial Reports of the Deep Sea Drilling Project, 42(2). Eds. D.A. Ross, Y.P. Neprochnov. Washington: U.S. Government Printing Office, pp. 483–488.

68. Sungatullina G.M., Silantiev V.V., Miftakhutdinova D.N., Safarov A.F., Validov M.F., Ganiev B.G., Shumatbaev K.D., Khabipov R.M. (2025). First insights into the Devonian–Carboniferous boundary conodonts from the depression deposits of the Kama-Kinel Trough System, East European Platform (Volga-Ural petroleum province, Sarailinskaya Depression). Uchenye Zapiski Kazanskogo Universiteta. Seriya Estestvennye Nauki, 167(1), pp. 130–153. (In Russ.) https://doi.org/10.26907/2542-064X.2025.1.130-153

69. Thompson J.B., Mullins H.T., Newton C.R., Vercoutere T.L. (1985). Alternative biofacies model for dysaerobic communities. Lethaia, 18(2), pp. 167–179. https://doi.org/10.1111/j.1502-3931.1985.tb00695.x

70. Trapp E., Kaufmann B., Mezger K., Korn D., Weyer D. (2004). Numerical calibration of the Devonian–Carboniferous boundary: Two new U-Pb isotope dilution-thermal ionization mass spectrometry single-zircon ages from Hasselbachtal (Sauerland, Germany). Geology, 32(10), pp. 857–860. https://doi.org/10.1130/G20644.1

71. Tyson R.V., Pearson T.H. (Eds.) (1991). Modern and ancient continental shelf anoxia. Geological Society London, Special Publications, 58, 470 p. https://doi.org/10.1144/GSL.SP.1991.058.01.01

72. Voitovich E.D. (2003). Tectonics of the sedimentary cover. Geology of Tatarstan: Stratigraphy and tectonics. Ed. B.V. Burov. Moscow: GEOS, pp. 313–336. (In Russ.)

73. Walters C.C. (2006). The Origin of Petroleum. Practical Advances in Petroleum Processing. Eds. C.S. Hsu, P.R. Robinson. New York: Springer. https://doi.org/10.1007/978-0-387-25789-1_2

74. Walters C.C. (2017). Origin of Petroleum. Springer Handbook of Petroleum Technology. Eds. C.S. Hsu, P.R. Robinson. Cham: Springer. https://doi.org/10.1007/978-3-319-49347-3_10

75. Warning B., Brumsack H.J. (2000). Trace metal signatures of eastern Mediterranean sapropels. Palaeogeography, Palaeoclimatology, Palaeoecology, 158(3–4), pp. 293–309. https://doi.org/10.1016/S0031-0182(00)00055-9

76. Wignall P.B. (1994). Black shales. Geology and Geophysics Monograph Series, 30. Oxford: Oxford University Press, 136 p.

77. Wignall P.B., Hallam A. (1991). Biofacies, stratigraphic distribution and depositional models of British onshore Jurassic black shales. Modern and ancient continental shelf anoxia. Geological Society London, Special Publications, 58, pp. 291–309.

78. Winston R.B. (1986). Characteristic features and compaction of plant tissues traced from permineralized peat to coal in Pennsylvanian coals (Desmoinesian) from the Illinois Basin. International Journal of Coal Geology, 6(1), pp. 21–41. https://doi.org/10.1016/0166-5162(86)90023-6

79. Xu J., Hou H., Ramezani J., Fang Q., Zhang S., Yang T., Chu Z., Wu H. (2024). Geochronological constraints on the Hangenberg Event of the latest Devonian in South China. Palaeogeography, Palaeoclimatology, Palaeoecology, 642, 112147. https://doi.org/10.1016/J.PALAEO.2024.112147

80. Yudovich Ya.E., Ketris M.P. (1988). Geochemistry of black shales. Leningrad: Nauka, 272 p. (In Russ.)

81. Yurchenko A.Yu. (2017). Formation of secondary carbonate rocks of the Upper Abalak-Bazhenov succession of the Salym, Pravdinsk and Malobalyk oil fields of Western Siberia. Cand. Sci. dissertation. Moscow, 133 p. (In Russ.)

82. Zhang Y., Li J., Chen L., Wei Y., Shi Q., Wang D.-G., Wu Q.-M., Song L.-Y., Tian M., Kuang H.-W., Liu Y.-Q., Mänd K., Bai H.-Q., Liu Z.-L., Wang Y.-Ch., Qiao D.-W., Zhu W.-J. (2021). Manganese carbonate stromatolites of the Ediacaran Doushantuo Formation in Chengkou, northern Yangtze Craton, China. Journal of Palaeogeography, 10(22). https://doi.org/10.1186/s42501-021-00099-9

83. Ziegler W. (1962). Taxionomie und Phylogenie oberdevonischer Conodonten und ihre stratigraphische Bebeutung. Abhandlungen des Hessischen Landesamtes für Bodenforschung, 38, pp. 1–166.

84. Ziegler W. (1969). Eine neue Conodontenfauna aus dem höchsten Oberdevon. Fortschritte Geologie von Rheinland und Westfalen, 17, pp. 179–191.

85. Ziegler W. (1971). Conodont Stratigraphy of the European Devonian. Geological Society of America Memoirs, 127, pp. 227–284. https://doi.org/10.1130/MEM127-p227

86. Ziegler W., Sandberg C. (1984). Palmatolepis-based revision of upper part of standard Late Devonian conodont zonation. Geological Society of America Special Paper, 196, pp. 179–194. https://doi.org/10.1130/SPE196-p179

87. Ziegler W., Sandberg C. (1990). The Late Devonian Standard Conodont Zonation. Courier Forschungsinstitut Senckenberg, 121, pp. 1–115.

88. Zonal stratigraphy of the Phanerozoic of Russia (2006). Ed. T.N. Koren’. St Petersburg: VSEGEI, 256 p. (In Russ.)