Naslov
Early/middle Miocene ostracod fauna from Mt. Požeška gora ; how the non-marine ostracods met marine

Autori
Hajek Tadesse, Valentina

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
8th International Workshop Neogene of Central and South-Eastern Europe Abstract Volume Field Trip Guidebook / Studencka, Barbara - Varšava : University of Warsaw, Faculty of Geology, Institute of Geology, 2019, 46-47

ISBN
978-83-945216-8-4

Skup
8th International Workshop: Neogene of Central and South-Eastern Europe

Mjesto i datum
Chęciny, Poljska, 27.05.2019. - 31.05.2019

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Ostracods, Karpatian, Badenian, Mt. Požeška gora

Sažetak
Ostracod data from the non - marine and marine Miocene deposits of Mt. Požeška gora were presented in this study. The Mt. Požeška gora is located in eastern Croatia in the southern part of the Pannonian Basin. It consists mostly of Neogene sediments with a volcanic mass in its central and north-eastern part. During the Miocene Mt. Požeška gora was located in the central part of the North Croatian Basin, at the south-western margin of the Pannonian Basin System. Formation of the North Croatian Basin started in the Lower Miocene with freshwater deposits, and was replaced in the base of the Middle Miocene by fully marine conditions as a consequence of the transgression by the Paratethys Sea. Dynamic evolution of the sedimentary basin, in a geologically short time, resulted with a great diversity of ostracods fauna. Ostracods are small, bivalve crustaceans that are found in all aquatic and some terrestrial habitats. In Lower/Middle Miocene non-marine and marine sediments of Mt. Požeška gora ostracods are common fossils and have been widely utilized for paleoenvironmental interpretations. Lacustrine ostracods are especially useful because they document the possible exchange of water between lakes and seas. Especially their importance should be emphasized in transitional marginal environments, as indicators of hydrodynamics and salinity. According to past and recent investigation four main ostracod groups were identified according to the assemblage composition and the presence of indicator species. First ostracod group includes badly preserved, fragmented, scattered freshwater valves, which were identified in the oldest deposits. The oldest deposit was characterized by the accumulation of predominantly breccias and conglomerates, sand and siltstones. Stratigraphically above the oldest sediments lacustrine sediments were deposited. The coeval transition from first lake deposits to laminated organic-rich marls suggests a rapid expansion and deepening of the lake. Lacustrine sediments are marked by very rich ostracods of the second group with the most abundant and frequent freshwater genus Heterocypris, Amplocypris, Candona, Cypris, Darwinula, Eucypris, Paralimnocythere, Potamocypris, Fabaeformiscandona, Cypridopsis and Herpetocypris. First ingression of marine water into the Early Miocene Lake was documented with the content of the third group of ostracods, and especially indicator genera of marine origin: Cyprideis, Aurila, Leptocythere and Amnicythere. Significantly, the oldest lake ostracod fauna indicates that the lake had already developed before any potential marine incursion took place. The lake system probably formed close to sea level and therefore the basin could, have been temporarily connected to the Paratethys Sea. The last ostracod group is characterized by fully marine assemblages which is a result of the transgression by the Paratethys Sea. After the stabilization of the marine palaeoenvironment the ostracod fauna enriched significantly in both nearshore and offshore environments. A very common genera in the deep-water environment are Krithe, Parakrithe, Henryhowella, Argilloecia, Acanthocythereis, Paracypris and Bythocythere ; in transitional, shallow-water/deep-water environment Pterygocythereis, Echinocythereis, Bosquetina, Cytherella and Ruggieria ; and shallow-water environment Aurila, Tenedocythere, Callistocythere, Costa, Cytheridea, Xestoleberis, Semicytherura and Olimfalunia.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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