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Sediments belonging to the Oligocene Vima Formation (located in the north-western part of the Transylvanian Basin, Romania) have been investigated for calcareous nannofossils content. Biostratigraphically, the sedimentary succession is late Rupelian–Chattian in age, belonging to the NP24 — Sphenolithus distentus and NP25 — Sphenolithus ciperoensis biozones, to CP19a — Cyclicargolithus floridanus and CP19b — Reticulofenestra bisecta Subzones and to the interval from CNO4 — Sphenolithus distentus/Sphenolithus predistentus CRZ to CNO5 — Sphenolithus ciperoensis TZ. The palaeoenvironment of the Fântânele section was reconstructed by means of calcareous nannofossils and statistics. Multivariate statistics were applied to the composition of autochthonous assemblages and the obtained clusters were used to assess the palaeoecological preferences of the nannofossils. We document changes from more stable open-marine regime, with temperate sea-surface temperatures interfering locally with influx of cooler water and enriched cool-nutrient supply for the late Rupelian–earliest Chattian (NP24), to shallower and possibly warmer near-shore marine eutrophic environment, with salinity fluctuations, increased terrigenous material run-off and freshwater influx for the remaining early Chattian (NP25).

This paper focuses mainly on the representatives of calcareous nannofossils and invertebrates from the Hrvaćani section of the Middle Miocene (Badenian) (Prnjavor Basin, southern margin of Pannonian Basin), and it defines the time of Badenian transgression in this area. Rich resources of fossil mollusk species, isolated parts of coral colonies, and other invertebrate remains were found in the investigated section. Moreover, turtle remains from marine sediments at the southern margin of Central Paratethys were recorded for the first time. Calcareous nannofossil biostratigraphy has established an NN5 Zone by the presence of Sphenolithus heteromorphus and the absence of Helicosphaera ampliaperta. The foraminifera associations from the analyzed sandstones belong to the Lower Badenian, namely the older zones of Ammonia viennensis and Elphidium crispum (the equivalent of Lagenidae Zone of Vienna Basin). The specimen of a turtle is currently attributed to order Testudines (suborder Pleurodira). From a stratigraphic and paleoecological point of view, all the fossil assemblages showed similar patterns for the subject of study, reflecting favorable conditions for developing a subtropical fauna in the open shallow marine environment. Consequently, by combining nannofossils, foraminifers, corals, malacological, and herpetological data, we can conclude that the early Middle Miocene (Badenian) in Hrvaćani (Bosnia) corresponds to the Lagenidae Zone (NN5 Zone) and was characterized by a relatively warm climate. [ABSTRACT FROM AUTHOR]

The Oligocene Ruslar Formation, an equivalent of the Maykop Suite, is a potential hydrocarbon source rock in the western Black Sea Basin. In contrast to the offshore areas, the depositional environment and hydrocarbon source rock potential of onshore Bulgaria sediments are largely unknown. Hence, a 14-m-thick section of the Ruslar Formation, exposed near Karadere (Black Cape) along the Black Sea coast, provides an excellent opportunity to study the upper part of the Ruslar Formation. Here, laminated diatomrich mudstones with frequent thin sandstone beds and a prominent concretion horizon are exposed. Furthermore, the fossil diatom assemblages provide a key component to understand the paleoenvironment. Overall, Paleogene diatoms are understudied in the Black Sea Basin and therefore only a genus-level study is undertaken here. The studied Ruslar Formation contain remarkably diverse and wellpreserved diatom assemblage with 23 different genera. The most frequent genera are Paralia, Distephanosira, and Stephanopyxis. Common genera include Coscinodiscus, Hemiaulus, Pseudopodosira, Rouxia, and Xanthiopyxis. Rare taxa include Actinoptychus, Asterolampra, Azpeitia, Delphineis, Distephanosira, Diploneis, Eunotogramma, Eurossia, Lyrella, Liradiscus, Plagiogramma, Radialiplicata, Rutilaria, Saeptifera, and Triceratium. The diatom assemblages together with calcareous nannoplankton, silicoflagellates, and the presence of rare foraminifera indicate a fully marine neritic environment without major salinity variations. The calcareous nannoplankton investigated can be assigned to biozone NP23 (Early Oligocene). The exposed fragment of the Ruslar Formation was deposited after the low salinity "Solenovian event", which represents the maximum isolation of the Paratethys present in the lower part of the NP23. Bulk geochemical parameters from 35 samples (avg. TOC: 1.80% wt.; avg. HI: 226 mg HC/g TOC) show that the exposed part of the Ruslar Formation contains type II-III kerogen and a fair to good hydrocarbon potential. The Ruslar Formation is immature (avg. Tmax: 424 °C), but may generate about 0.5 tons of hydrocarbons per square meter if mature. Biomarker proxies support the low maturity and are characterized by diatom-related biomarkers (24-norcholestane; C25HBI alkanes and thiophenes). Land-plant-derived biomarkers suggest a significant input of angiosperms. Based on biomarker ratios, the depositional environment was oxygen-depleted but probably not strictly anoxic. Reworking of biomass by chemoautotrophic bacteria is suggested by the presence of 28,30-bisnorhopane. [ABSTRACT FROM AUTHOR]

Quantitative and semi-quantitative analyses of calcareous nannofossils were performed on samples collected from Bozdovec Section (Albanian-Thessalian intramontane basin, Albania). The calcareous nannofossil assemblages are dominated by: small reticulofenestrids, Cycligargolithus floridanus, Coccolithus pelagicus, Sphenolithus spp., Reticulofenestra scrippsae, Helicosphaera spp., Clausicoccus spp., Reticulofenestra bisecta, Cycligargolithus abisectus. Biostratigraphically, the studied outcrop is assigned to the Late Oligocene NP25 - Sphenolithus ciperoensis Zone. In the Mediterranean area, this interval can be correlated with the MNP25a - Sphenolithus ciperoensis Zone, while according to the zonation for low to middle latitudes the investigated material would belong to the CNO5 - Sphenolithus ciperoensis TZ. High amounts of small reticulofenestrids and sphenoliths point to warm well stratified paleoenvironment. [ABSTRACT FROM AUTHOR]

This is the first detailed stratigraphic correlation of Lower and Middle Miocene deposits in the Gulf of Suez, Egypt using dinoflagellate cysts. The correlation is based on 273 ditch-cutting samples from five onshore boreholes located along the southwestern margin of the Gulf of Suez. The interval studied is represented by the Nukhul, Rudeis and Kareem formations of the Gharandal Group, and the lower part of the Belayim Formation of the Ras Malaab Group. These Miocene deposits unconformably overlie the Lower or lower Middle Eocene. The dinoflagellate cyst record is more diverse than previously reported and many taxa are documented for the first time in Egypt. Five biozones are established and tied to a chronostratigraphic framework by calibration to calcareous nannofossils (NN biozones) obtained from the same set of samples: (1) Lingulodinium machaerophorum Assemblage Biozone (GOS1), Aquitanian through mid-Burdigalian; (2) Exochosphaeridium insigne Taxon-range Biozone (GOS2), lower through mid-Burdigalian; (3) Apteodinium spiridoides Interval Biozone (GOS3), mid-Burdigalian through lower Langhian; (4) Cleistosphaeridium placacanthum Interval Biozone (GOS4), upper Burdigalian, Langhian, and lower Serravallian?); and (5) Polysphaeridium zoharyi Assemblage Biozone (GOS5), upper Langhian and Serravallian? Comparison with other Miocene biozonations from the Mediterranean, Central Paratethys, North Atlantic region, and eastern USA indicate that the highest occurrences of Apteodinium spiridoides, Cordosphaeridium cantharellus, Distatodinium paradoxum, Exochosphaeridium insigne and Cleistosphaeridium placacanthum, and the lowest occurrences of Exochosphaeridium insigne and Sumatradinium soucouyantiae are important datums, whereas the lowest occurrences of Hystrichosphaeropsis obscura, Labyrinthodinium truncatum, and Operculodinium? borgerholtense provide useful supporting age control. [ABSTRACT FROM PUBLISHER]