ISSN: 3005-9321 (print version)

Brachiopods as indicators of the Upper Devonian Frasnian sedimentation in the Timan-Pechora oil and gas province

Bakulina L.P., Dovjikova Y.G.

Ukhta State Technical University, Russia, Komi Republic, Ukhta, Pervomaiskaya str., 13: luda5200@bk.ru, dovzh57@yandex.ru


DOI: 
10.35714/ggistrat20240100006


Summary.
The paper describes faunal complexes formed in the north of the European part of Russia under different facies conditions during the Frasnian stage of the Upper Devonian period. The main inhabitants of the Frasnian sea basin were cephalopods – ammonoids and bactritoids, characterized by a rich species diversity of brachiopods, ostracods, bivalves, echinoderms, conodonts, coniconchians and radiolarians. These complexes are somewhat similar to the Frasnian complexes of the Russian Platform and the Western slope of the Ural Mountains. A particularly important role in the division of the Frasnian sections played brachiopods – inhabitants of the 30-200 m depth intervals of the warm shallow-water basins with normal salinity. Characterized by characteristic bi-valve, bilaterally symmetrical shells with different relief, these brachiopods are the most important indicator of the physicochemical conditions of sedimentation. To date, more than sixty brachiopod species with different shapes, sizes and shell surface structures have been detected and described in the Upper Devonian Frasnian stagsse of the Timan-Pechora oil and gas province.

Each substage, horizon and formation of the Frasnian stage is characterized by its own set of brachiopod species distinguished for their specific morphological features. It brings to a conclusion that the studied rocks had been formed under different facies conditions during four major sedimentation cycles the Timan (Timan formation), Khvorostan (Ustyarega formation), Semiluk (Domanik and Vetlasyan formations) and Don (Sirachoy and Ukhta formations).

Keywords: the Frasnian stage, the Timan-Pechora oil and gas province, facies conditions, faunal complexes, brachiopods, sedimentation cycles


REFERENCES

Bakulina L.P., Dovjikova Y.G. Lithology and structure of the upper Devonian domanik formation of southern Timan. Stratigrafy and sedimentology of oil-gas basins / Azerbaijan National Academy of Earth Sciences, 2. 2021, pp. 3-8.

Keyserling A. Krusenstern P. Scientific observations on a journey to the Petschora country in the year 1843. Carl Kray. St.-Petersburg, 1846, 467 s. (in German).

Maximova S.V. Ecological and facies features and conditions of formation of Domanic. Nauka. Moscow, 1970, 83 p. (in Russian.)

Parmuzina L.V., Borovinsky A.P. Rhythmicity of Upper Devonian sediments of Timan-Pechora Province. Vestnik of the Institute of Geology of Komi SC UB RAS, No. 3, 2012, pp. 2-5. (in Russian).

Schenk Ch.J. Chapter 18: Geology and petroleum potential of the Timan-Pechora Basin Province, Russia. Geological Society, London, Memoirs, Vol. 35(1), 2011, pp. 283-294, https://doi.org/10.1144/M35.18.

Yudina Y.A., Moskalenko M.N. Key sections of the Frasnian stage of the Southern Timan. Field guide for the International Sub-Commission on the stratigraphy of the Ukhta Devonian. VSEGEI (Russian Geological Research Institute) Publishing House. St. Petersburg, 1997, 79 p. (in Russian).