The Badenian/Sarmatian boundary in the Central Paratethys has been traditionally identified by the faunal turnover recording an important environmental change possibly controlled by the change from marine to brackish conditions. The strata below the Badenian/Sarmatian boundary in the northern Carpathian Foredeep are included into the Pecten beds, and those above it into the Syndesmya beds. Foraminiferal study of the Babczyn 2 borehole which is one of the crucial sections in the northern Carpathian Foredeep, well-known for the depositional age of rhyolite tuff within the Pecten beds dated by Śliwiński et al. (2012) at 13.06 ±0.11 Ma, indicated that in fact the boundary occurs within the Syndesmya beds. This conclusion is based upon the rapid change from a stenohaline foraminiferal fauna to a euryhaline one, and the appearance of the species Anomalinoides dividens, the taxon regarded as the marker for the Sarmatian. In the Babczyn 2 and Cieszanów 1 (located ~2.5 km basinward of Babczyn 2) boreholes, Anomalinoides dividens appears 3.1-3.8 m above the replacement of stenohaline by euryhaline foraminifers. The calcareous nannoplankton study shows that the upper Badenian and the lower Sarmatian strata in the studied sections represent the NN6, undivided NN6-NN7, and NN7 zones.
Seven Middle Miocene (Upper Badenian to Lower Sarmatian) sedimentary sections of the Central Paratethys, two from the Polish Carpathian Foredeep Basin (PCFB) and five from the Eastern Carpathian Foreland Basin (ECFB) of Romania and the Republic of Moldova have been analysed micropalaeontologically to better constrain the Badenian-Sarmatian Extinction Event, characterized by significant taxonomic impoverishment of both foraminifers and ostracods. Our studies show significant palaeoenvironmental changes in the basin including depth, salinity, oxygenation, and organic matter flux. The occurrence of moderately diverse planktonic foraminifera (Globigerina, Globigerinita, Globorotalia, Trilobatus, Orbulina, Velapertina) in the Upper Badenian deposits of the PCFB as well as in the ECFB and their rarity in the lowermost Sarmatian indicate an almost fully marine environment during the latest Badenian, followed by a significant regression and possible appearance of much more restricted marine conditions across the boundary. The taxonomic composition of the Sarmatian foraminifera, ostracoda and calcareous nannofossils indicate that during this interval the salinity fluctuated strongly, with the water regime varying from brackish to normal marine. In addition, the identified micropalaeontological assemblages identified show palaeoenvironmental similarity across different basins of the Central Paratethys. This supports a hypothesis of possible connections during the latest Badenian between different areas of the Central Paratethys, as well as of the existence of a gateway between the Central Paratethys and the Mediterranean realm.
The area of investigation is situated close to the contact zone between the Pieniny Klippen Belt, Krynica Subunit of the Magura Nappe and the Neogene strata of the Orava–Nowy Targ Intramontane Basin (southern Poland). In the area studied, marine deposits of the Stare Bystre Formation outcrop at the surface where they emerge from beneath freshwater and terrestrial Neogene and Quaternary deposits. Nannofossil assemblages from all samples are strongly dominated by reworked species. The Early Miocene age (NN2) of the Stare Bystre Formation has been determined on the base of the first occurrence of Sphenolithus disbelemnos after Shackleton et al. (2000). During the Late Oligocene (NP25/NN1), the frontal part of Magura Nappe was thrust northwards on to the terminal Krosno flysch basin. The northwards thrusting of the Magura Nappe was accompanied by the formation of the piggy-back basin on the Magura Nappe, filled with the synrorogenic turbidites belonging to the Zawada, Kremná and Stare Bystre formations (NN2).
Status and correlation of Andean ammonite biozones are reviewed. Available calpionellid, nannofossil, and radiolarian data, as well as radioisotopic ages, are also considered, especially when directly related to ammonite zones. There is no attempt to deal with the definition of the Jurassic–Cretaceous limit. Correlation of the V. mendozanum Zone with the Semiforme Zone is ratified, but it is open to question if its lower part should be correlated with the upper part of the Darwini Zone. The Pseudolissoceras zitteli Zone is characterized by an assemblage also recorded from Mexico, Cuba and the Betic Ranges of Spain, indicative of the Semiforme–Fallauxi standard zones. The Aulacosphinctes proximus Zone, which is correlated with the Ponti Standard Zone, appears to be closely related to the overlying Windhauseniceras internispinosum Zone, although its biostratigraphic status needs to be reconsidered. On the basis of ammonites, radiolarians and calpionellids the Windhauseniceras internispinosum Assemblage Zone is approximately equivalent to the Suarites bituberculatum Zone of Mexico, the Paralytohoplites caribbeanus Zone of Cuba and the Simplisphinctes/Microcanthum Zone of the Standard Zonation. The C. alternans Zone could be correlated with the uppermost Microcanthum and “Durangites” zones, although in west central Argentina it could be mostly restricted to levels equivalent to the “Durangites Zone”. The Substeueroceras koeneni Zone ranges into the Occitanica Zone, Subalpina and Privasensis subzones, the A. noduliferum Zone could be equivalent to the Dalmasi Subzone, Occitanica Zone, to lower part of the Boissieri Zone, and the S. damesi Zone could range through the upper part of the Boissieri Zone to the lower part of the Pertransiens Zone. Division of the Substeueroceras koeneni Zone and a precise correlation between the Andean ammonite zones and the international standard require new systematic and stratigraphic studies.
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Results of detailed multistratigraphic analyses of the Campanian.Maastrichtian boundary section at Kronsmoor in northern Germany are summarised and calibrated with the GSSP at Tercis les Bains, southwest France. Additional markers for the definition of the boundary in the Boreal Realm are proposed, and a detailed carbon isotope curve around the Campanian.Maastrichtian boundary in the chalk facies of the Boreal epicontinental sea is presented. The C isotopic GSSP marker for global correlation is the markedly abrupt decrease of c. 0.7 [per mil] [delta^13]C directly at the Campanian.Maastrichtian boundary as dated by ammonites. In electronic borehole measurements the Kronsmoor section covers the SP peaks 53 to 64 and the base of the Maastrichtian being situated just below SP peak 60. The first occurrence (FO) of the ammonite Pachydiscus neubergicus, which corresponds to biohorizon 1 at Tercis, falls in the upper part of nannofossil Zone UC15, at both localities. Biohorizon 3 is the FO of the ammonite Diplomoceras cylindraceum, which first appears in the Upper Campanian of Tercis and at Kronsmoor enters significantly above the FO of Belemnella lanceolata, the conventional Boreal belemnite marker for the base of the Maastrichtian Stage. Based on ammonite evidence, the internationally accepted base of the Maastrichtian at Kronsmoor is located between the FOs of Diplomoceras cylindraceum (Upper Campanian) and Pachydiscus neubergicus (Lower Maastrichtian) c. 11 m above flint layer F 600, at which the first representatives of the belemnite genus Belemnella, in particular Bn. lanceolata occur. The latter thus is a Late Campanian species, appearing c. 450 ky prior to the ammonite-based boundary. The FOs of Belemnella pseudobtusa (sensu Schulz) resp. Belemnella obtusa (sensu Remin) directly at the boundary can be use as the coleoid proxy for the definition of the base of the Maastrichtian in the Boreal Realm. To define the boundary by benthic foraminifera the last occurrence (LO) of Neoflabellina praereticulata is suitable. Biohorizon 12, as defined at Tercis, involves the nannofossil Uniplanarius trifidus, however, at Kronsmoor this species is rare, occurs only sporadically and also significantly lower in comparison to Tercis. It is possible though to compare and correlate nannofossil events between Kronsmoor and Tercis using cosmopolitan taxa such as Broinsonia parca constricta and Eiffellithus eximius. The LO of the latter appears to be situated just above the boundary in both sections; it follows from this that the top of nannofossil Zone UC15 is of Early Maastrichtian age.
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The Hanifa Formation in Saudi Arabia consists of a succession of carbonates, over 90 m thick that were deposited during the Late Jurassic, Oxfordian. It consists of a lower Hawtah Member and an upper Ulayyah Member. A Late Oxfordian age is based on the first appearance of the benthonic foraminifera Alveosepta jaccardi and, within the upper part of the underlying Hawtah Member, the local extinctions of the calcareous nannofossil species Watznaueria manivitiae and Stephanolithion bigotii together with an influx of Ellipsagelosphaera britannica. A detailed study of the micropalaeontology, nannopalaeontology, biofacies, sedimentology and wireline log character of the uppermost parts of 35 cored wells distributed across the Kingdom has revealed a variety of depositional environments. The late highstand succession of the Formation displays a variety of biofacies and lithotextures, of which the grainiest host the Hanifa Reservoir. These are associated with stromatoporoid banks that developed on the flanks of intrashelf basins, although grain-dominated shoals within the lagoons also present reservoir potential. A range of palaeoenvironments has been determined, based on integrated biofacies and lithofacies that include shallow lagoon packstones and foramininiferal dominated grainstones, deep lagoon wackestones and packstones with Clypeina/Pseudoclypeina dasyclad algae, stromatoporoid back bank packstones and grainstones with the branched stromatoporoid Cladocoropsis mirabilis, bank crest grainstones with encrusting and domed stromatoporoids and intrashelf basin flank mudstones and wackestones containing sponge spicules, deep marine foraminifera and coccoliths. This study has assisted delimitation of an intrashelf basin with an irregular margin situated in the East Central part of the Saudi Arabian portion of the Arabian Plate palaeoenvironments during the Late Oxfordian. The basin is flanked by a belt of stromatoporoid banks that pass laterally into a back-bank facies before developing into a lagoon facies. There is no evidence for the shoreline of this basin, although the presence of rare charophytes in the northwest testifies to possible proximity of fluviatile input. The grainstone margin presents good hydrocarbon reservoir facies and its juxtaposition to intrashelf basinal sediments with potential source rock character provides exciting new prospects in areas hitherto uninvestigated for hydrocarbon reservoirs.
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Temporary exposures of Upper Maastrichtian to Palaeocene sediments of the Richard Bay area, Kwa Zulu yielded Maastrichtian and Danian cephalopod faunas. The lower Upper Maastrichtian assemblage, dated to nannofossil standard biozone CC25b, or UC20a^TP of BURNETT (1998), is: Anagaudryceras politissimum (KOSSMAT, 1895), Pseudophyllites indira (FORBES, 1846) (abundant), Desmophyllites diphylloides (FORBES, 1846) Pachydiscus (P.) australis HENDERSON & McNAMARA, 1985, Menuites fresvillensis (SEUNES, 1890), Diplomoceras cylindraceum (DEFRANCE, 1816), Baculites ambatryensis COLLIGNON, 1971, Eubaculites carinatus (MORTON, 1834), and E. latecarinatus (BRUNNSCHWEILER, 1966). The Danian yields a monospecific assemblage of Hercoglossa madagascariensis COLLIGNON, 1951. The Maastrichtian assemblage has strong similarities to the lower Upper Maastrichtian fauna of the Miria Formation of Western Australia, and is made up of cosmopolitan and latitudinally restricted taxa: there are no endemic elements.
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