СТРАТИГРАФИЯ И МИКРОФАУНИСТИЧЕСКАЯ ХАРАКТЕРИСТИКА ТАВДИНСКОЙ СВИТЫ ЗАПАДНОЙ СИБИРИ

• Main Authors: Подобина, Вера, Чернышов, Алексей
• Format: Text
• Language: unknown
• Published: Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Национальный исследовательский Томский государственный университет" 2012
• Subjects: ТАВДИНСКАЯ СВИТА; СТРАТИГРАФИЯ; МИКРОФАУНА; НИЖНИЙ ОЛИГОЦЕН; Arctic; Greenland; Norway; Arctic Basin; Foraminifera*; ob river; Siberia
• Online Access: http://cyberleninka.ru/article/n/stratigrafiya-i-mikrofaunisticheskaya-harakteristika-tavdinskoy-svity-zapadnoy-sibiri; http://cyberleninka.ru/article_covers/13983769.png

Исследованы литологический состав и микропалеонтологические комплексы тавдинской свиты одноименного горизонта по разрезам скважин Западной Сибири. Виды фораминифер сравнивались с таковыми Европы, Атлантического океана, США и Канады. Установлен возраст свиты как раннеолигоценовый на основании находок характерных планктонных, бентосных фораминифер и остракод. По полученным данным уточнена стратиграфия свиты. Over the course of many years, the Tavdinskaya suite has been studied in order to ascertain the lithology and stratigraphy of this part of the marine Palaeogene of Western Siberia. Numerous borehole sections have been studied in Transuralia and especially in the southern part of Western Siberia (southward the latitudinal flow of the Ob River). At that time the basin was connected with southern seas through the straights in Turgay and northern Urals. Since the beginning of the Oligocene, the northern part of Western Siberia and the whole Arctic Region were exposed to the upward tectonic movements. This resulted in the shallowing and separation of the West-Siberian and Canadian basins and widening of the straight between Greenland and Norway. As it has previously been stated [2], calcareous secreted foraminifers migrated to the West Siberian Basin from the Atlantic Ocean via the shallowed warmed Arctic Basin and farther through the straight in the northern Urals. This may be evidenced by the systematic composition of foraminifers wherein European and American species of benthos and planktonic forms are present. There are no similar foraminifers in the Eocene and Oligocene of Kazakhstan. The most characteristic distinguished planktonic forms are as follows: Paragloborotalia postcretacea (Mjatliuk), P. anguliofficinalis (Blow), Globanomalina micra (Cole), G. barbadoensis (Blow), Globigerina ouachitaensis Howe et Wallace gnaucki Blow et Banner, G. angustiumbilicata Bolli, G. ampliapertura Bolli, G. officinalis Subbotina praesentata Podobina. Besides the planktonic forms, the characteristic calcareous benthos species were encountered: Cibicidoides pseudoungerianus (Cushman), Nonionellina oligocenica (Cushman et McGlamery), N. оvata (Brotzen), Evolutononion decoratum (Cushman et McGlamery), E. advenum (Cushman) and elphidiids. The Early Oligocene foraminiferal assemblage of Western Siberia characterizes the Cibicidoides pseudoungerianus Protononion decoratum Zone occupying the most part of the section of the Tavdinskaya suite. One of the recently studied sections of this suite, wherein the Early Oligocene foraminifers were distinguished, is the borehole of Section 8 (depth 159.35-87.60 m) of the Russian-Polyanskaya Area southward Omsk on Kazakhstan borderline [2]. The systematic composition of foraminifers, the rate of their preservation and lithological characteristics of rocks are indicative of their dwelling in the shallow coastal southern part of the West Siberian basin. More comprehensive information on the systematic composition of the foraminiferal assemblages studied previously and their comparison with those of other regions, including the Rupelian typical section of Belgium, has been presented in other publications [1, 2]. In the Tavdinskaya suite, the underlying quartz-siliceous agglutinated species gave way to the predominating calcareous secreted forms. This is recorded by us both in the West Siberian Province and in the Canadian one, thus indicating the general change of physical-andgeographical and bionomical conditions in the whole Arctic area.