Bulk and clay mineral composition indicate origin of terra rossa soils in Western Herzegovina

The B horizons of terra rossa soils developed on three different carbonate lithologies having variable insoluble residue contents were studied in Western Herzegovina. Comparison of  their composition and properties illustrates to what extent mineral (especially clay mineral assemblage) and particle size composition of those horizons and the insoluble residue of the underlying carbonate rocks can be used as indicators of the polygenetic nature of terra rossa in this region. Terra rossa B horizons have characteristic red colours, neutral to slightly acid pH, high base saturation with calcium as the predominant cation and high CIA (Chemical Index of Alteration). The CIA values obtained are generally in accordance with mineral composition and particle size distribution of the analysed B horizons.  The predominant clay mineral phases in B horizons and related insoluble residues match. Kaolinite is the predominant clay mineral phase in the B horizons overlying carbonate rocks containing low amounts of insoluble residue, while smectite predominates in calcarenites areas with a high insoluble residue content.  However, the presence of plagioclase, gibbsite, chlorite-vermiculite mixed layer mineral and vermiculite in B horizons overlying carbonate rocks containing low amounts of insoluble residue support a polygenetic origin for the terra rossa. In contrast, terra rossa formed on calcarenites containing high amounts of insoluble residue might have formed almost exclusively from the parent carbonate rock although some influence of external materials (e.g. gibbsite) cannot be excluded. This investigation shows that in Western Herzegovina, an area with no important aeolian input, the content and mineral composition of carbonate rock insoluble residue plays a major role in terra rossa composition.  We can tentatively conclude that the lower the insoluble residue content of the parent materials, the greater is the expectation of a more polygenetic origin for the terra rossa

IN SEARCH OF THE EGGENBURGIAN – OTTNANGIAN BOUNDARY AT THE SOUTHEASTERN MARGIN OF THE BOHEMIAN MASSIF (LOWER AUSTRIA)

At the south-eastern margin of the Bohemian Massif in Lower Austria Eggenburgian to Ottnangian sediments are widespread. In the wider surroundings of Eggenburg nearshore clastic deposits of the upper Eggenburgian (Kühnring Mb., Burgschleinitz Fm., Gauderndorf Fm.) occur, which are discordantly overlain by shallow marine sublittoral bioclastic limestone of the Zogelsdorf Fm. Due to the ongoing transgression the Zogelsdorf Fm. shows a fining and deepening upward succession, passing upsection and laterally into marine clays and marls of the Zellerndorf Fm.Two completely cored logs from Limberg and Pulkau show this sedimentary succession above the crystalline basement. As in many outcrops, in the well Limberg KB2 on top of the Burgschleinitz Fm. a transgressional conglomerate occurs at the base of typical Zogelsdorf Fm. followed by pelites of the Zellerndorf Fm. The well Pulkau S1 exhibits between clastics of the Burgschleinitz Fm. and sands and limestone of the Zogelsdorf-Fm. a 4.5 m pelitic sequence with two tuffitic horizons. Between those notdateable tuffitic clays, badly sorted gravelly and sandy clay with molluscs like Granulolabium plicatum, Ostrea digitalina, Perna aquitanica, Cerastoderma edule, Taras rotundatus, Tellina planata, Cordiopsis incrassatus, Turritella sp., and Natica sp. indicates a deepening upward lagoonal environment. In dark gray fine bedded silty clays above thin shelled bivalves (Cardiidae, Veneridae, Lucinidea) and gastropods (Turritella eryna, Granulolabium plicatum) also point to shallow marine lagoonal conditions. This pelitic sequence is concordantly overlain by sands and sandy limestone of the Zogelsdorf Fm. and silty clay of the Zellerndorf Fm.Calcareous nannoplankton associations from the Burgschleinitz Fm. in Limberg KB2 can be correlated by Triquatrorhabdulus carinatus and Helicosphaera ampliaperta with the upper part of NN2. Sediments from the Zogelsdorf Fm. in the lower part of Limberg KB2 can be assigned to NN2/NN3 by H. ampliaperta and T. carinatus. Assemblages with H. ampliaperta and Reticulofenestra excavata in the lowermost part of the Zellerndorf Fm. in Pulkau S1 point to NN3.The successions in both wells show at the base upper Eggenburgian marine deposit (Burgschleinitz Fm.) followed by a regressional phase and a renewed transgression initiating the deposition in lagoonal facies in Pulkau S1. This regression presumably correlates with the main regional hiatus at the base of the Zogelsdorf Fm. and can be consequently correlated with the 3rd Order Sequence Stratigraphic Boundary Bur 3

Benthic algae as major precursors of oil-prone kerogen – A case study from the Hungarian Middle Miocene

This study is intended to clarify the depositional environment of a 180-m-thick, immature, limy Middle Miocene oil source rock interval, cored in the Zala Basin, western Hungary. For this purpose, a highly interdisciplinary approach was applied combining simple, standard micropaleontological, isotopic, and organic geochemical methods, rarely applied together. Foraminifera were studied for estimating bottom oxygenation and water depth, while nannoplankton biostratigraphy permitted for estimating the rate of sedimentation. The studied source rocks were deposited in a rather shallow sea, below well-oxygenated bottom water. The abundant epiphytic foraminiferal fauna proves that the bottom was densely inhabited by benthic algae, while the high δ13Corg (>–22‰) clearly indicates massive benthic algal contribution to the kerogen. Mass accumulation rate of the limy upper part of the NN5 nannoplankton biozone, the oil source interval included, was very high (551 t/m2/Ma). In spite of moderate productivity and good oxygenation of the bottom, rapid accumulation of carbonate, produced partly by benthic algae, assured both the great relative weight of the marine organic components and their good preservation. Our results provide the first proof for the possibility of a major contribution of benthic algae to oil-prone kerogen

Environmental shifts in and around Lake Pannon during the Tortonian Thermal Maximum based on a multi-proxy record from the Vienna Basin (Austria, Late Miocene, Tortonian)

The Neogene Lake Pannon was the largest lake that ever existed in Europe. It attained its greatest extent during the Tortonian Thermal Maximum. For the first time, results from a detailed lake record documenting about 85 kyr of Late Miocene time in a continuously recovered, 60-m-long, clay-rich core of Lake Pannon are reported. This record includes the transition from the lake's maximum transgression into its highstand at around 10.4 Ma. The environmental development of Lake Pannon during its maximum extent is interpreted based on integrated paleontological, sedimentological, mineralogical and geochemical data. The maximum extent coincided with stable sedimentation of clay, little influx from the hinterland, low surface productivity and severe bottom-water anoxia. The clay mineralogy of the lower part of the core points to prevailing chemical weathering based on the illite/smectite ratios. Distinct Fe, Mn and Ba enrichments are interpreted to have formed close to sulfate-methane transition zones during the maximum flooding. The highstand phase was marked by rapid environmental shifts with frequent phases of well‑oxygenated bottom waters. These phases are reflected by rich benthic communities including stenohaline tunicates. The increased input of detritic kaolinite suggests a shift towards physical weathering and higher precipitation coinciding with a shift in the provenance of clay minerals. Increasing amounts of nutrients stimulated surface water productivity and nannoplankton blooms. Despite the offshore position of the core at ∼8 km from the mountainous ranges of the Alps, strong fluvial input is reflected from 32.5 to 30.3 m by coarser sediment and the occurrence of terrestrial and freshwater molluscs. The Rhenodanubian Flysch Unit was the main source of the siliciclastics of the core and was drained by the Paleo-Wien river. Drainage from the Calcareous Alps was limited to an exceptionally strong fluvial event and related deposits, which documents the presence of a second river in the southwest, which might represent the Paleo-Liesing. The dominance of smectite throughout the core suggests a temperate climate with distinct seasonality during the Tortonian Thermal Maximum. In view of the autochthonous ascidian sclerites in three samples, and assuming generally similar ecological requirements for both Pannonian and modern tunicates, we conclude a polyhaline salinity for Lake Pannon around 10.4 Ma

SPECTACULAR INSIGHTS INTO ESTUARINE TO SHALLOW MARINE SEDIMENTS OF THE KARPATIAN (LOWER MIOCENE) IN THE KORNEUBURG BASIN (LOWER AUSTRIA)

The Korneuburg Basin in Lower Austria, about 18 km north of Vienna, is a ca 20 km long and at most 7 km wide asymmetric pull-apart basin formed within the Alpine-Carpathian thrustbelt during last Alpine movements in the Karpatian (late Early Miocene). During the construction of the S1 motorway south of Stetten a ca 1.8 km long section between the Tradenberg tunnel and the city of Korneuburg was geologically documented in detail (fig. 1). A flysch-elevation in the area of profile E (fig. 1) divides the section in an eastern (profiles A, F) and a western part (profiles G, D, D1, B, C1, C) causing an increasing number of faults in the Miocene sediments towards the vicinity of the flysch. In the western part constantly 20° to 30° westward dipping marl, marly silts and fine to medium sands, in some parts with intercalations of lignite and coaly clay were cropping out, whereas in the eastern part the westward dipping of similar sediments is changing to an eastward nearby the flysch high.Rich fossil content documents sedimentation in mudflats, coastal swamps and shallow sublittoral settings within an estuary. Autochthonous Lower Miocene nannofossils represented by stratigraphical important forms like Helicosphaera ampliaperta Bramlette et Wilcoxon, 1967, H. carteri (Wallich 1877) Kamptner 1954, Reticulofenestra excavata Lehotayova, 1975, Sphenolithus cf. heteromorphus Deflandre 1953, indicating nannoplankton Zone NN4 (Martini 1971). The mollusc fauna documents changing environmental conditions along the sampled transect. Nearby terrestrial habitats and freshwater influence are indicated by planorbids, hydrobiids and Melanopsis impressa. An enormous biodiversity with more than 650 taxa was documented from these paleoenvironments, allowing also precise climatic reconstruction from palynologic data: within subtropical climatic conditions intertidal to very shallow subtidal marine environments and brackish water with Agapilia pachii, Granulolabium plicatum, Terebralia bidentata, Crassostrea gryphoides, and Perna aquitanica; whereas deeper subtidal and fully marine conditions are documented by Turritella, Nassarius, Anadara, muricid gastropods, or venerids. Foraminiferal assemblages are dominated by benthic foraminifera and document brackish to shallow marine paleoenvironments. Most frequent genera are Ammonia, Aubignyna and elphidiids. Quiet water assemblages are indicated by higher portions of Caucasina and Nonion. The found assemblages enable us to trace sea level changes within the sections. They correspond largely to those described earlier by Rögl (1998). A complete measurement by hand-held gammalog spectral analysis detected throughout the succession prominent, highly significant periodicities with stratigraphic distance ranging from 12 m to 25 m, which have been interpreted as 21-kyr-precession signal. This indication for astronomical forcing allows further discussion of a reliable age-model for this section of the Korneuburg Basin

Calcareous nannofossils from the middle/upper Miocene succession of Pécs-Danitzpuszta, southern Hungary: cosmopolitan Paratethys and endemic Lake Pannon assemblages

Quantitative analyses on calcareous nannofossils were carried out on 109 middle/late Miocene (Sarmatian/ Pannonian) samples from the section at Pécs-Danitzpuszta sand pit (Hungary). The lower part of the section, which can be assigned to the Sarmatian, contains normal marine low-diversity assemblages dominated by Calcidiscus leptoporus, Reticulofenestra pseudoumbilicus, Sphenolithus moriformis and Syracosphaera spp. accompanied by didemnid ascidian spicules (Perforocalcinela fusiformis). The middle/late Miocene (Sarmatian/Pannonian) boundary is characterized by the last occurrences of normal marine calcareous nannofossils. The upper part of the section (Pannonian) can be subdivided into intervals characterized by monospecific endemic nannofossils Isolithus spp. and ascidians, respectively. A short interval with common endemic coccoliths belonging to the family Noelaerhabdaceae (Bekelithella echinata, Noelaerhabdus bozinovicae, N. jerkovici, Praenoelaerhabdus banatensis) in the upper part of the profile was also documented. The drastic change in nannofossil assemblages at the Sarmatian/Pannonian boundary is a result of paleoenvironmental stress caused by the isolation of the Central Paratethys from the Eastern Paratethys

Late Oligocene calcareous nannofossils from Albanian-Thessalian intramontane basin (Bozdovec Section, Albania) – a quantitative approach

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