Middle Devonian conodonts of the Southern Verkhoyansk Region

Givetian conodonts demonstrate a wide geographical distribution and are instrumental in establishing biostratigraphic correlations at both regional and global levels. Nevertheless, their study in the Southern Verkhoyansk Region has only recently begun. I initially identified these conodonts in Tikhii Creek basin situated on the right bank of the first left tributary of Komar Creek, adjacent to the Vostochnaya Khandyga River, the Sette-Daban Range. In this area, the gypsum-bearing sediments of the Tikhiiskaya Suite underlie the carbonate Zagadochninskaya Suite. During a state-funded geological survey, these suites were classified as the Burkhalinskaya series. Geologists assigned the conglomerates at the base of the Tikhiiskaya Suite and the variegated sediments overlain by basalt to the Givetian Stage. This study suggests that the boundary between the Lower and Middle Devonian periods should be delineated at the base of the conglomerate strata, while the variegated volcanic strata capped by basalt should be classified within the Emsian Stage of the Lower Devonian. The findings related to five taxa of conodonts, which belong to two successive complexes originating from the boundary deposits of the Eifelian and Givetian Stages found along Komar Creek, are reported for the first time. The lower complex, distinguished by the presence of conodonts such as Dvorakia sp., Icriodus expansus Branson and Mehl (1938), Polygnathus parawebbi Chatterton (1974), P. costatus subspecies A, P. parawebbi, and Neopanderodus pearleneatus (Ziegler and Lindström 1971), is identified within the Upper Eiffelian Stage. Conversely, the upper complex, which includes subspecies Polygnathus linguiformis linguiformis Hinde (1879) and P. xylus xylus Stauffer (1940), is indicative of the Givetian Stage. The boundary between the Eiffelian and Givetian Stages in the Tikhii-Komar section is likely situated between beds 5 and 6. Consequently, based on the conodont data, the Tikhiiskaya Suite should be classified as Eiffelian in age. Presumably, the basal layers of the Zagadochninskaya Suite correspond to this same geological stage.

1. Becker R.T., Gradstein F.M., Hammer O. The Devonian Period. In: Gradstein F.M., Ogg J.G., Schmitz M.D., Ogg G.M. (eds.). The Geologic Time Scale 2012. Amsterdam, Netherlands: Elsevier BV; 2012, pp. 559-601. https://doi.org/10.1016/B978-0-444-59425-9.00022-6

2. Becker R.T., Marshall J.E.A., Da Silva A.-C., et al. The Devonian Period. In: Gradstein F.M., Ogg J.G., Schmitz M.D., Ogg, G.M. (eds.). Geologic Time Scale 2020. Amsterdam, Netherlands: Elsevier; 2020, pp. 733-810. https://doi.org/10.1016/B978-0-12-824360-2.00022-X

3. Baranov V.V. The Middle and Upper Devonian in southeastern flank of the Siberian platform (Southern Verkhoyansk Region, Sette-Daban Mountain Range). Stratigraphy and Geological Correlation. 2007;15(5): 470-484. https://doi.org/10.1134/S0869593807050024

4. Baranov V.V., Alkhovik T.S. Brachiopods of the family Ambocoeliidae (Spiriferida) from the Givetian of Southern Verkhoyansk Region (Northeastern Russia). Paleontological Journal. 2006;40(2):162-167. https://doi.org/10.1134/S0031030106020067

5. Baranov V.V. New Devonian brachiopods from northeastern Russia. Paleontological Journal. 2007;41(3): 252-259, https://doi.org/10.1134/S0031030107030045

6. Saydam-Demiray D.G., Çapkınoğlu S. Conodont fauna and biostratigraphy of the Early-Middle Devonian units in Beykoz, Şile And Kurtdoğmuş Areas, İstanbul, Turkey. Bulletin of the Mineral Research and Exploration. 2012;145:1-21.

7. Pyle L.J., Orchard M.J., Barnes Ch.R., Landry M.L. Conodont biostratigraphy of the Lower to Middle Devonian Deserters Formation (new), Road River Group, northeastern British Columbia. Canadian Journal of Earth Sciences. 2003;40:99-113. https://doi.org/10.1139/E02-095

8. Klapper G., Barrick J.E Middle Devonian (Eifelian) conodonts from the Spillville Formation in northern Iowa and southern Minnesota. Journal of Paleontology. 1983; 57(6):1212-1243.

9. Johnson J.G., Klapper G., Trojan W.R. Brachiopod and conodont successions in the Devonian of the northern Antelope Range, central Nevada. Geologica et Palaeontologica. 1980;14:77-116.

10. Uyeno Th.T., Pedder A.E.H., Uyeno Th.A. Conodont biostratigraphy and T-R cycles of the Middle Devonian Hume Formation at Hume River (type locality), northern Mackenzie Mountains, Northwest Territories, Canada. Stratigraphy. 2017;14(1-4):391-404. https://doi.org/10.29041/strat.14.1-4.

11. Weddige K. Die Conodonten der Eifel-Stufe im Typusgebiet und in benachbarten Faziesgebieten. Senckenbergiana lethaea. 1977;58:271-419.

12. Stauffer C.R. Conodonts from the Devonian and associated clays of Minessota. J. Paleontol. 1940;14(5): 417-435.

13. Uyeno T.T. Pre-Famennian Devonian conodont biostratigraphy of selected intervals in the eastern Canadian Cordillera. Geological Survey of Canada Bulletin. 1991;417:129-161. https://doi.org/10.4095/132436

14. Ziegler W., Ovnatanova N., Kononova L. Devonian Polygnathids from the Frasnian of the Rheinisches Schiefergebirge, Germany, and the Russian Platform. Senck. Leth. 2000;80(2):593-645.

15. Ovnatanova N.S., Kononova L.I. Conodonts and Upper Devonian (Frasnian) biostratigraphy of central regions of Russian Platform. Courier Forschungsinstitut Senckenberg. 2001;233:1-115.

16. Ovnatanova N.S., Kononova L.I. Frasnian conodonts from the Eastern Russian Platform. Paleontological Journal. 2008;42(10):997-1166.

17. Narkiewicz K., Bulthynk P. Conodont biostratigraphy of the Upper Devonian in the Lublin area (southeastern Poland). 2011. Prace panstwowego instytutu geologicznego. 2011:193-254.

18. Ziegler W., Klapper G., Jonson I.G. Redefinition and subdivision of the varcus-Zone (Conodonts Middle - ?Upper Devonian) in Europe and North America. Geologica et Palaeontologica. 1976:109-140.

19. Bardashev I.A., Ziegler W. Conodonts from Middle Devonian section in Tadzhikistan (Kalagach Fm., Middle Asia, USSR). Courier Forsch.-Inst. Senckenberg. 1985:65-78.

20. Ovnatanova N.S., Kuzmin A.V. Conodonts of the Type Sections of the Domanik Formation on Southern Timan. Izv. Akad. Nauk SSSR, Ser. Geol. 1991; 3: 37-50.

21. Hinde G.J. On conodonts from the Chazy and Cincinnati group of the Cambro-Silurian and from the Hamilton and Genesee Shale divisions of the Devonian, in Canada and the United States. United States. Quarterly Journal of the Geological Society of London.1879; 35:351-369.

22. Uyeno T.T. Conodont faunas. In: Middle Devonian brachiopods, conodonts, stratigraphy, and transgressive-regressive cycles, Pine Point area, south of Great Slave Lake, District of Mackenzie, Northwest Territories. Geological Survey of Canada, Bulletin 522, 1998; 146- 191. Ottawa: Part II.

23. Liao J.-C., Valenzuela-Ríos J I. Givetian and early Frasnian conodonts from the Compte section (Middle- Upper Devonian, Spanish Central Pyrenees). Geological Quarterly. 2008;52(1):1-18.

24. Walliser O.H., Bultynck P. Extinctions, survival and innovations of conodont species during the Kaák Episode (Eifelian-Givetian) in southeastern Morocco. Bulletin de l’Institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre. 2011;81:5-25.

25. Bultynck P. Révision stratigraphique et paléontologique (Brachiopodes et Conodontes) de la coupe type du Couvinien. Mémoires de l’Institut Géologique de l’Université de Louvain. 1970;26:1-152.

26. Ziegler W., Klapper G. Redefinition and subdivision of the varcus-Zone (Conodonts, Middle-? Upper Devonian) in Europe and North America. Geologica et Paleontologica. 1976;10:109-140.

27. Chatterton B.D.E. Middle Devonian conodonts from the Harrogate Formation, southeastern British Columbia. Canadian Journal of Earth Sciences, 1974;11:1461-1484.

28. Kononova L.I., Kim S.Y. Eifelian conodonts from the central Russian platfom. Paleontological Journal. 2005;39:S55-S134.

29. Narkiewicz M., Litostratygrafia, systemy depozycyjne i cykle transgresywno-regresywne dewonu basenu lubelskiego. Prace - Panstwowego Instytutu Geologicznego. 2011;196:53-146.