Tidal deposits in the Early Miocene Central Paratethys: the Vučji Jarek and Čemernica members of the Macelj formation (NW Croatia)

The Macelj formation is an informal Eggenburgian-early Ottnangian lithostratigraphic unit that is established in the area of the Hrvatsko Zagorje Basin, which represented a marginal zone of the Early Miocene Central Paratethys Sea. Modern studies, as a part of the Geologic Map of the Republic of Croatia 1:50 000 project, yielded new data that improves the knowledge of the depositional and stratigraphic characteristics of the formation. The sedimentological research within this study was focused on the two older lithostratigraphic units of the Macelj formation: the Vučji Jarek member and the Čemernica member. The Vučji Jarek mb. is represented by three facies. The Facies of horizontally bedded sandstones is characterized by mostly medium-grained, moderately sorted sandstones that reflect deposition on the foreshore to the upper shoreface. The facies of horizontally and cross-bedded glauconitic sandstones is composed of fine- to coarsegrained, well-sorted sandstones that indicate foreshore to shoreface deposition under tidal influence. The Facies of horizontally and cross-bedded pyroclastics consists of tuff, pumice, lapilli and large blocks, showing a chaotic structure in places. Deposition occurred at the shoreface under tidal influence. The Čemernica mb. is represented by the Facies of structureless clayey-silty sands that are poorly sorted and bioturbated, and indicates deposition below the fairweather wavebase, in the offshore-transition zone. Deposits of the members include marine macro- and microfossil associations.K-Ar dating of separated glauconite mineral fractions yielded an early Eggenburgian age for the Vučji Jarek mb. glauconitic sandstones (19.2±0.64 Ma) which is in accordance with biostratigraphical analyses. Sedimentological characteristics of the Eggenburgian Macelj fm., especially those that reflect the tidal influence, fit the general characteristics of the Central Paratethys Sea in the Early Miocene

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

Geologic reconnaissance of the island of Velika Palagruža (central Adriatic, Croatia)

Velika Palagruža (Pelagosa) is the largest island of the Palagruža archipelago (central Adriatic Sea, Croatia). Despite its minute size the island bears a certain geological interest being the only exposed piece of land in the central part (Mid-Adriatic ridge) of the common Adriatic foreland of the Apenninic and the Dinaridic orogenic domains. The litho-, bio-, and chemostratigraphic (strontium and sulphur isotopes) characteristics of the sedimentary units, along with tectono-structural and geomorphic characteristics of the island, are described in this paper. The oldest Žalo unit is composed of highly deformed siliciclastics containing gypsum, and carbonates of Middle Triassic (Ladinian) age. This unit represents a transitional fl uvial-to-shallow marine, occasionally evaporitic environment, typical of the Middle Triassic rifting phase of the Adriatic microplate. Soft and strongly deformed Žalo unit deposits are found along a probably still active, WNW&ndash;ESE striking, subvertical, oblique-slip fault that crosses the entire length of the island. The Žalo unit is probably in diapiric contact with the Lanterna unit, poorly defi ned as Late Triassic, and characterized by dolomite with chert and dolomite breccia, presumably deposited in a transitional platform-to-basin environment of an evolving Adriatic basin. The Lanterna unit deposits are capped by Miocene biocalcarenites of the Salamandrija unit over an almost perpendicular discordance, possibly representing an unconformity, suggesting that an early deformational phase preceded a Miocene marine transgression. Talus, landslide deposits, and humic soil make up the cover of the bedrock sedimentary succession, and they represent the ultimate phase of emersion of the island, which probably occurred during Pliocene(?) to Quaternary times. An active neotectonic regime of the central Adriatic is evidenced by present-day seismicity, while recent uplifting of the island is shown by the presence of remnants of pebbly palaeobeach deposits, marine (erosional) straths, and cyanobacterial supratidal encrustations (pelagosite) currently observed at various elevations above mean sea level. </span

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

Geologic reconnaissance of the island of Velika Palagruža (central Adriatic, Croatia)

Velika Palagruža (Pelagosa) is the largest island of the Palagruža archipelago (central Adriatic Sea, Croatia). Despite its minute size the island bears a certain geological interest being the only exposed piece of land in the central part (Mid-Adriatic ridge) of the common Adriatic foreland of the Apenninic and the Dinaridic orogenic domains. The litho-, bio-, and chemostratigraphic (strontium and sulphur isotopes) characteristics of the sedimentary units, along with tectono-structural and geomorphic characteristics of the island, are described in this paper. The oldest Žalo unit is composed of highly deformed siliciclastics containing gypsum, and carbonates of Middle Triassic (Ladinian) age. This unit represents a transitional fl uvial-to-shallow marine, occasionally evaporitic environment, typical of the Middle Triassic rifting phase of the Adriatic microplate. Soft and strongly deformed Žalo unit deposits are found along a probably still active, WNW&ndash;ESE striking, subvertical, oblique-slip fault that crosses the entire length of the island. The Žalo unit is probably in diapiric contact with the Lanterna unit, poorly defi ned as Late Triassic, and characterized by dolomite with chert and dolomite breccia, presumably deposited in a transitional platform-to-basin environment of an evolving Adriatic basin. The Lanterna unit deposits are capped by Miocene biocalcarenites of the Salamandrija unit over an almost perpendicular discordance, possibly representing an unconformity, suggesting that an early deformational phase preceded a Miocene marine transgression. Talus, landslide deposits, and humic soil make up the cover of the bedrock sedimentary succession, and they represent the ultimate phase of emersion of the island, which probably occurred during Pliocene(?) to Quaternary times. An active neotectonic regime of the central Adriatic is evidenced by present-day seismicity, while recent uplifting of the island is shown by the presence of remnants of pebbly palaeobeach deposits, marine (erosional) straths, and cyanobacterial supratidal encrustations (pelagosite) currently observed at various elevations above mean sea level