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New data about Santonian-Campanian boundary in the Alan-Kyr section (Central Crimea)тезисы доклада
- Авторы: Proshina P.A., Kopaevich L., Guzhikov A., Aleksandrova G., Ovechkina M., Ryabov I.
- Сборник: 3rd International Congress on Stratigraphy, Abstract Book
- Тезисы
- Год издания: 2019
- Место издания: Società Geologica Italiana Roma
- Первая страница: 286
- Последняя страница: 286
- Аннотация: Keywords: Santonian-Campanian, Crimea, Foraminifera, Nannoplankton, Palynomorph, Magnetostratigraphy. One of the problematic boundaries of the Upper Cretaceous is the base of the Campanian, for which GSSP has not yet been established. In the Central Crimea, the Santonian-Campanian boundary interval is represented by a lithologically monotonous carbonate deposits. In the absence of macrofossils, the boundary can be established by microfossil and magnetostratigraphic techniques. The Coniacian-Campanian interval of the Alan-Cyr section (Central Crimea) was studied by Bragina et al. (2016). There was a discrepancy in stratigraphy by the benthic foraminifera on the one hand, and the planktic foraminifera and radiolarians on the other. Therefore, a comprehensive additional study of the Alan-Kyr section deposits was carried out by authors in order to clarify the issue of the boundary position for nannoplankton, palynomorphs and foraminifera using the magnetostratigraphy. At the lower part of the section, according to the results of magnetostratigraphic studies, the chron of reverse polarity was established, correlated with chron 33r, the base of which equals in the International stratigraphic scale to the base of the Campanian. Nannoplankton data confirm the conclusions about the correct interpretation of the interval of reverse polarity. At this level the transition Zone ??17 (Upper Santonian) is established. Above in the section Zone CC18 (Lower Campanian) is recognized. Palynomorphs are fixed in this interval, which is compared with the Newhaven Chalk Formation and part of the Margate Chalk (corresponds to Santonian too). In the lower part of section (Zone CC17) typical Santonian-Campanian bentic and plaktic foraminifera were established. At the terminal part of CC17 Pseudogavelinella clementiana clementiana (d’Orb.) was encountered, indicating a transitional level of the terminal Santonian–Lower Campanian. Zone CC18 is characterized by Lower Campanian planktic foraminifera Globotruncana elevata (Brotz.), above in the section G. ventricosa (White), Heterohelix sphaeralis (Georg.) (Middle Campanian) are established. As a result, the characteristics of the Alan-Kyr section have been supplemented in comparison with the published data. Campanian age of the upper part of the section is confirmed to the data from previous researchers (Bragina et al., 2016). Lower part of the section is determined as Coniacian by Bragina et al. (Bragina et al., 2016) vs. dated by our data Santonian-Lower Campanian. This research was supported the RFBR: 18-05-00784-a, 18-05-00503 and was carried out of the frame work of State Task Theme 0135-2018-0036 (GIN RAS).
- Добавил в систему: Копаевич Людмила Федоровна