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The palynological assemblages of the Middle Jurassic of the Russian Platformтезисы доклада
- Автор: Rostovtseva J.I.
- Сборник: 9th European Palaeobotany=Palynology Conference
- Тезисы
- Год издания: 2014
- Место издания: Padova-Italy
- Первая страница: 235
- Последняя страница: 236
- Аннотация: The samples for palynological analysis were collected from seven outcrops and three boreholes. These outcrops located in central region of the Russian platform. Eight palynological assemblages were established. The palyassemblage I is characterized by domination of pollen grains (over 54% of the total). The grains of Alisporites similis, Alisporites oblatinoides is dominated among pollen constituting 13% of the assemblage. Besides the pollen, there are some spores (46%). The systematic composition of the spores is various. Spores of Filicopsida are Dicthyophyllidites harrisii, Cyathidites minor. There are Uvaesporites verrucosus, Neoraistrickia suratensis, Antulsporites verrucatus, Lycopodiumsporites intortivallus, which are typical for the Bajoician deposits. Thus studied palynological assemblage has the Bajocian age. The palynoassemblage II is distinguished by domination the spores (69%) over pollen. The spores of Cyatheaceae (25%) and Gleicheniaceae (10%) are presented. A lot of ancient forms of spores (Klukisporites variegatus, Staplinisporites caminus, Neoraistrickia rotundiformis) reveals about Lower Bathonian age. It is also important that pollen Classopollis (1,2%) appears in minor amount. The assemblage III is characterized by domination of spores of Gleicheniaceae (19%). The typical zonation species for the Bathonian stage (Sestrosporites, psevdoalveolatus, Callialasporites dampieri) are found. For the callovian age five assemblages is distinguished. The main feature of the palynoassemblage IV is the prevalence of pollen gymnosperms over spores. It should be noted the first appearance Gleicheniidites apilobatus and pollen grains Cycadopites jansonii. The amount of pollen Classopollis is increased to 35%. The palynoassemblage V is dominated by Classopollis pollen 46%. The Lycopodiumsporites caperatus и Alisporites grandis is appeared for the first time. It is necessary to note that assemblage V consists of 50% algae. The composition of the pollen assemblage in the middle Callovian rocks is varied from the lithologic composition of rocks as observed in our palynoassamblage VI. The bissacate pollen is dominated in sandy rocks. Pollen Classopollis (up to 40%) is a big part of the assemblage in clay rocks. Concavisporites jurienensis appears for the first time for the Middle Callovian. The palynological assemblages VII and VIII are similar. Both assemblages are characterized by domination of Classopollis from 26% in VII to 36% in VIII. However, assemblage VIII is characterized by first appearance of Gleicheniidites apilobatus and G. rasilis. Two abundance peaks of marine dinocysts occur in ammonite zones Proplanulites koenigi and Quenstedtoceras lamberti that indicate two transgressive events during Early and Late Callovian. The research was supported by Russian Foundation for Basic Researches, project No 13-05-00423.
- Добавил в систему: Ростовцева Юлия Игоревна