litosphereЛитосфераLITHOSPHERE (Russia)1681-90042500-302XA.N. Zavaritsky Institute of Geology and Geochemistry10.24930/1681-9004-2023-23-3-348-366litosphere-1880Research ArticleСтатьиArticlesОстракодовая зональность живетско-франского пограничного интервала в Тимано-Североуральском регионеOstracod zonation of the Givetian-Frasnian boundary interval in the Timan-North Urals RegionСоболевД. Б.SobolevD. B.

167000, г. Сыктывкар, ул. Первомайская, 54

54 Pervomaiskaya st., Syktyvkar, 167000, Russia

dbsobolev@rambler.ruСоболеваМ. А.SobolevaM. A.

167000, г. Сыктывкар, ул. Первомайская, 54

54 Pervomaiskaya st., Syktyvkar, 167000, Russia

matusha.888@mail.ruЕвдокимоваИ. О.EvdokimovaI. O.

199106, г. Санкт-Петербург, ул. Средний проспект В.О., 74

74 Srednii Prospect, St.Petersburg 199106, Russia

irina_evdokimova@vsegei.ruИнститут геологии ФИЦ Коми НЦ УрО РАНРоссияInstitute of Geology FRC Komi SC UB RASRussian FederationФГБУ «Всероссийский научно-исследовательский геологический институт им. А.П. Карпинского»РоссияKarpinsky Russian Geological Research Institute (FGBU “VSEGEI”)Russian Federation202309072023233348366Copyright © Соболев Д.Б., Соболева М.А., Евдокимова И.О., 20232023Соболев Д.Б., Соболева М.А., Евдокимова И.О.Sobolev D.B., Soboleva M.A., Evdokimova I.O.Данная работа распространяется под лицензией Creative Commons Attribution 4.0.This work is licensed under a Creative Commons Attribution 4.0 License.https://www.lithosphere.ru/jour/article/view/1880Объект исследования

Объект исследования. Остракоды и пограничные живетско-франские отложения Тимано-Североуральского региона.

Материал и методы

Материал и методы. В основе работы лежат результаты изучения остракод из стратотипических разрезов Южного Тимана, являющихся эталонными для региональных и глобальных корреляций. Анализ интервалов распространения наиболее значимых таксонов основан на результатах предшествующих как опубликованных, так и фондовых работ по Тимано-Уральскому региону. Остракоды рассмотрены в ассоциации с конодонтами, что является важным критерием для использования обоснованного биостратиграфического расчленения. Показано применение разномасштабной региональной цикличности осадконакопления, а также отдельных “маркирующих” уровней проявления глобальных событий.

Результаты

Результаты. Проведен анализ распространения остракод в живетско-франских пограничных отложениях Тимано-Североуральского региона. Выделены наиболее значимые таксоны: Cavellina devoniana, Cavellina uchtensis, Cavellina batalinae, Cavellina chvorostanensis, Nodella faceta, Nodella ex gr. hamata. Показана сопряженность установленных комплексов с остракодами Франко-Бельгийского бассейна. Отличие заключается в отсутствии полизигидного комплекса с Polyzygia beckmanni beckmanni, который установлен в основании формации Nismes Бельгии вблизи исторической границы между живетским и франским ярусами. Установленная сопряженность биостратиграфических данных с трансгрессивно-регрессивной последовательностью осадконакопления дает более обоснованное решение вопроса о положении нижней границы франского яруса верхнего девона в ТиманоСевероуральском регионе.

Выводы

Выводы. Учитывая особенности распространения остракод семейств Cavellinidae и Nodellidae, а также выявленные несоответствия уровней появления зональных видов с границами зон в региональной стратиграфической схеме, разработан обновленный вариант схемы зонального расчленения живетскофранского пограничного интервала в Тимано-Североуральском регионе. Показана корреляция остракодовых зон относительно конодонтовой шкалы.

Research subject

Research subject. Ostracods and Givetian-Frasnian boundary deposits of the Timan-North Urals Region.

Materials and methods

Materials and methods. The work was based on the results of studying ostracods from the stratotype sections of the Southern Timan, which are considered referential for regional and global correlations. The analysis of the distribution intervals of the most significant taxa was based on the results of previous studies, both published and archival materials on the Timan-Urals Region. Ostracods were considered in association with conodonts, which is an important criterion for applying a reasonable biostratigraphic subdivision. The use of different-scale regional cyclicity of sedimentation and individual “marking” levels of manifestation of global events were shown.

Results

Results. The ostracod distribution in the Givetian-Frasnian boundary interval of the Timan-Northern Urals region was analyzed. The following most significant taxa were identified: Cavellina devoniana, Cavellina uchtensis, Cavellina batalinae, Cavellina chvorostanensis, Nodella faceta, Nodella ex gr. hamata. The correlation of established assemblages with ostracods from the Franco-Belgian basin was shown. The difference consists in the absence of a polyzygid assemblage with Polyzygia beckmanni beckmanni, which was established at the base of the Nismes Formation of Belgium near the historical boundary between the Givetian and Frasnian stages. The determined relationship of biostratigraphic data in combination with the transgressive-regressive sequence of sedimentation shows a more reasonable solution to the problem of the position of the lower boundary of the Frasnian stage of the Upper Devonian in the Timan-Northern Urals Region.

Conclusions

Conclusions. An updated version of the scheme of zonal subdivision of the Givetian-Franian boundary interval in the Timan- Northern Urals region has been developed, taking into account the ostracod distribution of the Cavellinidae and Nodellidae families, as well as the discrepancies in the levels of the first appearance of index species and the boundaries of zones in the regional stratigraphic scheme. The correlation of ostracod zones relative to the conodont scale is shown.

Тимано-Североуральский регионживетско-франский пограничный интервалсредний-верхний девонбиостратиграфиякорреляцияостракодыTiman-Northern Urals regionGivetian-Frasnian boundary intervalMiddle-Upper DevonianbiostratigraphycorrelationostracodsИсследования проводились в рамках государственного задания по теме № 122040600008-5 и при частичной поддержке гранта РФФИ № 20-05-00445.The research was conducted within framework of State Assignment No. 122040600008-5 and with partial financial support from the RFBR grant No. 20-05-00445.ReferencesГруздев Д.А., Соболева М.А., Соболев Д.Б., Журавлев А.В. (2016) Франские отложения на р. Большая Надота (Приполярный Урал) – стратиграфия и условия образования. Литосфера, (6), 97-116.Aboussalam Z.S., Becker R.T. (2007) New upper Givetian to basal Frasnian conodont faunas from the Taflalt (Anti-Atlas, Southern Morocco). Geol. Quart., 51(4), 345-374.Егоров В.Г. (1953) Остракоды франского яруса Русской платформы. Ч. 2. Bairdiidae, Hollinidae, Kirkbyidae. 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The authors declare that there are no conflicts of interest present.