Middle Miocene (Upper Badenian/Sarmatian) Palaeoecology and Evolution of the Environments in the Area of Medvednica Mt. (North Croatia)

In the area of Medvednica Mt., the Upper Badenian and Sarmatian deposits are divided into four facies associations: (A) deposits of a small carbonate platform represented by breccia, conglomerates, biocalcirudites, biocalcarenites and biocalclutites; (B) open-sea deposits composed of marls with intercalations of clay; (C) nearshore deposits of reduced salinity composed of conglomerates, sandstones, biocalcarenites, biocalcirudites and biocalclutites, and (D) lagoonal deposits represented by spongitic calclutites with clay, marl and sand intercalations. Deposits of these facies associations contain numerous and very diverse fossil species with very different palaeoecological characteristics, from shallow- and deeper-water normal marine to shallow- and deeper-water environment of reduced salinity, even of fresh-water. The transition from Late Badenian to Sarmatian deposition was characterized by three different unconformities and one conformity. Unconformities are located between different lithologies reflecting an amount of uplifting and erosion at the end of the Badenian. The occurrence of an angular unconformity suggests the influence of local tectonics. The Middle Miocene deposition shows different local variations but generally fits with the evolution of Central Paratethys and the Pannonian Basin System

Paleoecological and sedimentological characterisation of Middle Miocene sediments from the Hrvatska Kostajnica area (Croatia)

The Miocene deposits of the Hrvatska Kostajnica (KOS-I) area belong to the south-western marginal part of the Pannonian Basin System (PBS). Investigation of the lithostratigraphical column included: mineralogical, geochemical, sedimentological and integrated palaeontological (calcareous nannofossil, foraminifers, ostracodes, palynomorphs) analyses. Badenian and Sarmatian sediments of this column were deposited in a marine offshore environment with local input of terrigenous material represented by marls and silty marls. Based on palaeontological data, the recorded palaeoclimate was subtropical in the late Badenian changing to a warm temperate climate of the early Sarmatian. Marly sediments predominantly consist of carbonate (calcite and aragonite) and clay minerals, while quartz and plagioclase are less abundant. Most samples contain a small amount of zeolite minerals from the clinoptilolite/heulandite series. Among the clay minerals, smectite and illite/muscovite are the most abundant. Based on provenance analyses we concluded that the Badenian-Sarmatian marls were predominantly formed by the weathering of acidic (Si-rich) source rock derived material from the neighbouring Inner Dinarides.</p

Correlation of upper Miocene–Pliocene Lake Pannon deposits across the Drava Basin, Croatia and Hungary

Upper Miocene to Pliocene (Pannonian) sediments of the Pannonian Basin System accumulated in the brackish Lake Pannon and the fluvial feeder systems, between 11.6-2.6 Ma. Their stratigraphic subdivision has been problematic for a long time due to the laterally prograding architecture of the basin fill and the historically independently evolving stratigraphic schemes of the neighbouring countries. We correlated the lithostratigraphic units of the Lake Pannon deposits between Hungary and Croatia in the Drava Basin, using lithological, sedimentological and palaeontological data from boreholes and outcrops, and seismic correlation. The Croatica and Medvedski breg formations in Croatia correspond to the Endrőd Fm. in Hungary, comprising shallow to deep water, open lacustrine, calcareous to argillaceous marls. The Andraševec fm. in Croatia corresponds to the Szolnok and Algyő Fms. in Hungary, consisting of sandstones and siltstones of turbidite systems and of clay marls deposited on the shelf-break slope. The Nova Gradiška fm. in Croatia is an equivalent of the Újfalu Fm. in Hungary, built up of a variety of lithologies, including sand, silt, clay and huminitic clay, deposited in deltaic environments. The Pluska fm. in Croatia corresponds to the Zagyva Fm. in Hungary, consisting of variegated clays, silts, sands and lignites, deposited in alluvial and fluvial environments. Coarse-grained (sand, gravel) basal layers are assigned to the Kálla and Békés Fms. and the Sveti Matej member of the Croatica fm. Coarse-grained intercalations within the deep-water marls belong to the Dorozsma Member of the Endrőd Fm. in Hungary, and to the Bačun member of the Medvedski breg fm. in Croatia. Sediment transport and lateral accretion of the shelf edge in the Drava Basin took place from the N, NW, and W, to the S, SE, and E, respectively. According to the biostratigraphic and chronostratigraphic analyses, the oldest shelf-break slopes in the Mura Basin are more than 8 Ma old, whereas the youngest ones in the southeasternmost part of the Drava Basin may be Pliocene in age (younger than 5.3 Ma). Thus, the 180 km long and at least 700 m deep Drava Basin was transformed into a fluvial plain during the last 3.5 million years of the Miocene.</p

Upper Miocene ostracods from the Krško Basin, SE Slovenia

The purpose of this study was to identify the ostracod assemblage from a 43 m thick section of the Bizeljsko Formation, which constitutes the middle part of the Upper Miocene Posavje Group. The succession comprises sandstone, siltstone, and marlstone, deposited in a delta front environment. The determined ostracods belong to the families Cyprididae, Cytheridae, Darwinulidae, and Loxoconchidae. In total, 30 species were identified. Additionally, 8 morphotypes were determined at the genus level. The most common genera are Candona, Hemicytheria, and Cyprideis. The assemblage belongs to the Caspiocypris labiata subzone from the upper Pannonian. The ostracod assemblage from the Krško Basin is similar in species composition to Pannonian ostracod assemblages from Croatia and Serbia

Middle Miocene marine flooding: new 40Ar/39Ar age constraints with integrated biostratigraphy on tuffs from the North Croatian Basin

In the North Croatian Basin which is located in the southwestern part of the Pannonian Basin System, Miocene tuff deposits have been observed at several localities in the area of Banovina, Medvednica Mt. and Slavonia. Here we present new 40Ar/39Ar age results obtained from volcanic glass from the Laz tuff (15.42 ± 0.15 Ma) intercalated with lacustrine freshwater/brackish deposits, the Jovac tuff (15.10 ± 0.06 Ma) intercalated with lacustrine freshwater deposits, the Čučerje tuff (14.81 ± 0.08 Ma) and the Nježić tuff (14.40 ± 0.03 Ma) both deposited in a marine environment. Fossil data (calcareous nannofossils/foraminifera) from the underlying and overlying beds of the tuffs from Čučerje and Nježić match the geochronological data i.e. NN5 zone and M6 zone were determined. Integration of biostratigraphic and geochronological data enable a better understanding of the NCB sedimentary evolution and constrain the Middle Miocene marine flooding event in the marginal areas of the western part of the NCB at ~15 Ma i.e. early/middle Badenian boundary. These results together with the existence of lower Badenian marine sediments in the Sava depression (in the southern part of NCB) suggest it is possible to conclude that during the early Badenian in the NCB, freshwater lacustrine and marine  environments coexisted.

Sub-recent microfauna within allogenic sediments at the bottom of a deep cave, Njemica (Biokovo Mt., Croatia)

Clastic sediments deposited at the bottom of the vertical, nearly 1000 m deep Njemica Cave (Biokovo Mountain, Croatia) were analysed. Owing to the vertical morphology of the cave, the occurrences of clastic sediments are sparse. Small, up to decimetre-thick, undisturbed sediment accumulations situated near the siphon lake revealed interesting palaeontological and mineralogical data. These data are used as a useful proxy for discussing depositional processes, the provenance of the sediments and paleo-habitats of the subterranean fauna. The sub-recent assemblages of ostracods were discovered within the sediment, and they were shown to be correlative to the known endemic species in the wider Dinaric Karst area (Pseudocypridopsis sywulai and Phreatocandona cf. motasi). The well-preserved sediment archive indicates the allogenic origin of the sediment and defines it as an allochthonous infiltrate of the Quaternary. The detritus originates from Pleistocene–Holocene deposits in the surrounding area, whose composition was influenced by volcanic activity in the wide Adriatic region. Sedimentation occurred in a calm aquatic environment by settling from suspension. Therefore the sediments are defined as slackwater deposits

Sub-recent microfauna within allogenic sediments at the bottom of a deep cave, Njemica (Biokovo Mt., Croatia)

Clastic sediments deposited at the bottom of the vertical, nearly 1000 m deep Njemica Cave (Biokovo Mountain, Croatia) were analysed. Owing to the vertical morphology of the cave, the occurrences of clastic sediments are sparse. Small, up to decimetre-thick, undisturbed sediment accumulations situated near the siphon lake revealed interesting palaeontological and mineralogical data. These data are used as a useful proxy for discussing depositional processes, the provenance of the sediments and paleo-habitats of the subterranean fauna. The sub-recent assemblages of ostracods were discovered within the sediment, and they were shown to be correlative to the known endemic species in the wider Dinaric Karst area (Pseudocypridopsis sywulai and Phreatocandona cf. motasi). The well-preserved sediment archive indicates the allogenic origin of the sediment and defines it as an allochthonous infiltrate of the Quaternary. The detritus originates from Pleistocene–Holocene deposits in the surrounding area, whose composition was influenced by volcanic activity in the wide Adriatic region. Sedimentation occurred in a calm aquatic environment by settling from suspension. Therefore the sediments are defined as slackwater deposits

Evidence for Badenian local sea level changes in the proximal area of theNorth Croatian Basin

Quantitative analysis of palynomorphs, foraminifera and ostracods enabled the recognition of biotic events and the reconstruction of environmental change in the Badenian sediments from the Vrhovčak section of Mt. Samoborsko gorje (NW Croatia). During the Middle Miocene the investigated area of Mt. Samoborska gora was located at the south-western margin of the North Croatian Basin, which represents the south-western edge of the Pannonian Basin System and the Central Paratethys Basin. This marginal position within the basin controlled the specific evolution of the depositional area during the Badenian. The occurrence of coal bearing horizons and freshwater flora and fauna in the middle part of the Vrhovčak section provide new data for the reconstruction of Badenian palaeoenvironments. A fall in sea level and the probable isolation of this area in the Badenian seems to be responsible for the appearance of a new fauna and flora.The marine sediments from the base of the Vrhovčak section may be correlated to cycle TB 2.4 of the main Badenian transgression, which affected the entire Central Paratethys area. This was followed by a regression and lowstand (Ser2), which, correlated to the middle part of the section, with freshwater sediments and coal bearing horizons. The upper part of the Vrhovčak section with marine sediments represents the Late Badenian cycle TB 2.5.Quantitative analysis of palynomorphs, foraminifera and ostracods enables the recognition of biotic events and the reconstruction of environmental change in the Badenian sediments from the Vrhovčak section of Mt. Samoborsko gorje (NW Croatia). During the Middle Miocene the investigated area of Mt. Samoborska gora was located at the south-western margin of the North Croatian Basin, which represents the south-western edge of the Pannonian Basin System and the Central Paratethys Basin.This marginal position within the basin controlled the specific evolution of the depositional area during the Badenian. The occurrence of coal bearing horizons and freshwater flora and fauna in the middle part of the Vrhovčak section provide surprising details of investigation. A fall in sea level and a probable isolation of this area in the Badenian seems to be responsible for the appearance of a new fauna and flora. The marine sediments from the base of the Vrhovčak section may be correlated to the cycle TB 2.4 of the main Badenian transgression, which affected the entire Central Paratethys. This is followed by a regression and lowstand (Ser2), which is correlated to the middle part of the section with freshwater sediments and coal bearing horizons. The upper part of the Vrhovčak section with marine sediments represents the Late Badenian cycle TB 2.5.</p

Badenian and Sarmatian beds in excavation pit for the hydroelectric power plant Brežice, Slovenia

Geological prospection of partly accessible constructional pit for the hydroelectric power plant (HPP) Brežice was performed. Paleontological content and sediment-petrographic characteristics of rocks were investigated. Neogene part of the succession consists of carbonate silt and siltstone with intercalations of carbonate and silicate sandstone, and polymict sandstone to conglomerate. Based on foraminifera, ostracods, molluscs and marine mammals, the Upper Badenian and Lower Sarmatian age of beds and boundary between them have been determined. The transition is characterized by a shorter break in sedimentation and environmental change. Fossil fids indicate that salinity and depth of sedimentary basin were oscilating in Sarmatian, but in general decreasing. Quaternary cover beds consist of gravelly, sandy and silty deposits of the Sava River