Natália Hudáčková

Late Miocene surface uplift of the southern margin of the Central Anatolian Plateau, Central Taurides, Turkey

The timing and pattern of surface uplift of Miocene marine sediments capping the southern margin of the Central Anatolian Plateau in southern Turkey provide a first-order constraint on possible mechanisms of regional uplift. Nannofossil, ostracod, and planktic foraminifera biostratigraphy of the Basyayla section (Mut-Ermenek Basin) within the Mut and Koselerli Formations suggests a Tortonian age for marine sediments unconformably capping basement rocks at ∼2 km elevation. The identification of biozone MMi 12a (7.81–8.35 Ma) from planktic foraminifera in the upper part of the section provides the tightest constraint on the age, which is further limited to 8.35–8.108 Ma as a result of the reverse polarity of the collected samples (chron 4r.1r or 4r.2r). This provides a limiting age for the onset of surface uplift at the margin of one of the world’s major orogenic plateaus, from which an average uplift rate of 0.24–0.25 mm/yr can be calculated. Subhorizontal beds of the uppermost marine sediments exposed throughout the Mut-Ermenek Basin suggest minimal localized deformation, with just minor faulting at the basin margin and broad antiformal deformation across the basin. This implies that the post–8 Ma uplift mechanism must be rooted deep within the crust or in the upper mantle. Published Pn-wave velocity data for the region are compatible with topography compensated by asthenosphere across the southern margin of the plateau, showing a close match to the highest topography when elevations are filtered with a 100-km-wide smoothing window. Uplift along the southern margin of the Central Anatolian Plateau is also reflected by the pattern of Miocene marine sediments capping the margin, which form an asymmetric drape fold over the topography. These observations, together with tomographic evidence for slab steepening and break-off beneath the Eastern Anatolian Plateau, suggest that at least some of the ∼2 km of post–8 Ma uplift of the southern Central Anatolian Plateau margin is compensated by low-density asthenospheric mantle that upwelled following slab break-off.

Late Badenian foraminifers from the Vienna Basin (Central Paratethys): stable isotope study and paleoecological implications

Late Badenian foraminifers from the Vienna Basin (Central Paratethys): stable isotope study and paleoecological implications Paleoecological interpretations based on stable isotope study of benthic (Uvigerina semiornata) and planktonic (Globigerina bulloides, Globigerinoides trilobus) foraminiferal shells from the Paratethys Vienna Basin (southwestern Slovakia) are presented. The study was performed on sediments of the Devínska Nová Ves-clay pit deposited during the Middle and Late Badenian (Middle Miocene). Our δ13C data show an enhanced nutrient input to the water column and the organic matter accumulation at the bottom of the Vienna Basin. The remineralization of accumulated organic matter on the sea floor resulted in the formation of oxygen-depleted zones, where no oxic indicators but the oxygen-deficiency tolerant species were found. Positive benthic δ18O signal can be attributed to the influence of the global cooling recognized in the world-ocean during the Middle Miocene. At the same time, variations observed in the water column are interpreted as reflecting the local temperature and salinity changes resulting from the fluvial and rain inflow. The differences between surface and bottom water temperature reflect the stratification of the water column. Such stratification might be related to the isolation process of Central Paratethys in the Badenian. This study confirms that δ13C and δ18O are not always in isotopic equilibrium with the ambient water but are also influenced by vital effects (respiration, symbiont photosynthesis …). The vital effects led to the incorporation of isotopically light metabolic CO2 into Globigerina bulloides resulting in high similarity between δ13C values of Uvigerina and Globigerina. It has been shown that the extremely high δ13C and very low δ18O of Globigerinoides trilobus clearly imply the influence of algal photosymbionts.

Biostratigraphy, sedimentology and paleoenvironments of the northern Danube Basin: Ratkovce 1 well case study

Abstract The Ratkovce 1 well, drilled in the Blatné depocenter of the northern Danube Basin penetrated the Miocene sedimentary record with a total thickness of 2000 m. Biostratigraphically, the NN4, NN5 and NN6 Zones of calcareous nannoplankton were documented; CPN7 and CPN8 foraminifer Zones (N9, 10, 11 of the global foraminiferal zonation; and MMi4a; MMi5 and MMi6 of the Mediterranean foraminiferal zonation were recognized. Sedimentology was based on description of well core material, and together with SP and RT logs, used to characterize paleoenvironmental conditions of the deposition. Five sedimentary facies were reconstructed: (1) fan-delta to onshore environment which developed during the Lower Badenian; (2) followed by the Lower Badenian proximal slope gravity currents sediments; (3) distal slope turbidites were deposited in the Lower and Upper Badenian; (4) at the very end of the Upper Badenian and during the Sarmatian a coastal plain of normal marine to brackish environment developed; (5) sedimentation finished with the Pannonian-Pliocene shallow lacustrine to alluvial plain deposits. The provenance analysis records that the sediment of the well-cores was derived from crystalline basement granitoides and gneisses and from the Permian to Lower Cretaceous sedimentary cover and nappe units of the Western Carpathians and the Eastern Alps. Moreover, the Lower Badenian volcanism was an important source of sediments in the lower part of the sequence.

Brachiopods and bryozoans from the Sandberg section (ViennaBasin, Central Paratethys) and their significance forenvironmental interpretation of the Early Sarmatian (= MiddleMiocene) Sea.

Brachiopods and bryozoans are described for the first time from the upper part of the Sandberg section (Vienna Basin, Central Paratethys, Slovakia) dated by foraminifers and calcareous nannoplankton as Early Sarmatian (= Late Serravallian). Three brachiopod species, i.e. Gryphus miocenicus (Michelotti, 1847), Argyrotheca cuneata (Risso, 1826) and Joania cordata (Risso, 1826), have been identified. Bryozoans are represented by at least 11 species, i.e. Umbonula macrocheila (Reuss, 1847), Margaretta cereoides (Ellis et Solander, 1786), Plagioecia rotula (Reuss, 1847), Schizoporella dunkeri (Reuss, 1847), Calpensia gracilis (Munster, 1826), Escharella tenera (Reuss, 1874), Mollia cf. patellaria (Moll, 1803), Vibracella trapezoidea (Reuss, 1847), Smittina cervicornis (Pallas, 1766), Porella sp., and an unidentified calloporid. Despite the fact that brackish conditions are commonly expected in the Vienna Basin during this period, the assemblage indicates full marine (stenohaline) conditions.

TAPHONOMIC CLOCK AND BATHYMETRIC DEPENDENCE OF CEPHALOPOD PRESERVATION IN BATHYAL, SEDIMENT-STARVED ENVIRONMENTS

Abstract: The dependence of skeletal alteration on time spent in the taphonomic active zone (TAZ) can generate a taphonomic clock, which can be used to quantify scales of time averaging and rates of skeletal production and recycling in the fossil record. However, the strength of the taphonomic clock is variable in present-day shallow marine environments and it is unclear how this strength varies with depth. Here, we assess the strength of the taphonomic clock in Nautilus macromphalus dead shells that were collected in cool-water, sediment-starved, epi- and mesobathyal environments off New Caledonia and range in postmortem age from few decades to several millennia. We find that, first, differences in the onset and extent of alteration states in the epibathyal zone (< 750 m) segregate well-preserved shells with red stripes (less than ∼ 200 years) from encrusted shells with faded colors and extensively bored by sponges (∼ 400 years), and from strongly fragmented, bored, and coated shell relicts (> 1,000 years). The onset of dissolution and formation of clay-goethitic coating occurs earlier (∼ 200 years) in the mesobathyal zone (> 750 m) than in the epibathyal zone. Clay-goethitic rims and boring infills show signs of microbial binding, pelletization, and coccolith dissolution and can represent nascent stages of glauconitization. Second, shells several centuries old show differences between right and left flanks (1) in the degree of encrustation and sponge bioerosion in the epibathyal zone and (2) in the extent of clay-goethitic coating in the mesobathyal zone. The upper flanks are ultimately removed in both depth zones, leaving relict half-shells that are millennia old. Third, the depth dependence of alteration can reflect a bathymetric decline in disintegration rates by heterotrophic borers due to a reduced productivity in the mesobathyal zone and an increase in dissolution rates due to the proximity of the aragonite compensation depth. The between-flank asymmetry in preservation implies (1) horizontal position of shells close to the sediment-water interface for several decades or centuries without being overturned or subjected to reworking and (2) shell exposure to two distinct taphonomic regimes separated by few centimeters, with the upper flank located in the TAZ and the lower flank facing a less aggressive sediment zone. The stable exposure of shells in the taphonomic active zone and slow alteration rates in bathyal environments allow discriminating between within-habitat time-averaged assemblages on one hand and environmentally or stratigraphically condensed assemblages on the other hand.

Sepia from the Miocene of the Central Paratethys: new taxa and notes on late Cenozoic cuttlefish diversity

A new and locally abundant species of Sepia, S. juliebarborarum sp. nov., and single records of S. aff. loerentheyi and S. aff. sanctacrucensis from the upper Badenian of Slovakia and Austria, S. mikuzi sp. nov., S. aff. mikuzi sp. nov. and Sepia sp. from the middle Badenian of Slovenia, document a greater Miocene sepiid diversity in the Central Paratethys than previously recorded. In the present study, Miocene sepiids from the Central Paratethys are systematically revised and, in part, compared to other coeval taxa from elsewhere. Middle Miocene diversity in the Central Paratethys amounts to nine species, inclusive of four taxa retained in open nomenclature. Here we use the morphology of the dorsal shield and septal suture lines as key features for systematic assignment at the species level. Usage of the generic name Sepia for these Miocene sepiids is corroborated by uniquely preserved material of S. vindobonensis from the middle Badenian of Austria. This reveals only minor morphological differences during ontogeny from the Recent type species of Sepia, S. officinalis. The stratigraphical range of sepiids in the Central Paratethys is reinterpreted and shown to be early to late Badenian. Miocene Sepia diversity in the Central Paratethys is greater than previously supposed, which supports normal marine conditions and an open connection with the Mediterranean. http://zoobank.org/urn:lsid:zoobank.org:pub:3B32BA47-EB28-4A75-95FE-6349C08BB5EA.

Integrated biostratigraphical, sedimentological and provenance analyses with implications for lithostratigraphic ranking: the Miocene Komjatice depression of the Danube Basin

Abstract The Komjatice depression, situated on the Danube Basin’s northern margin, represents a sub-basin of the Neogene epicontinental Central Paratethys Sea and Lake Pannon. The paper provides an insight into the character of sediment provenance evolution by study of well cores (ZM-1, IV-1, MOJ-1, VR-1 wells). A modern combination of provenance, sedimentology and biostratigraphy together with the reported redefinition of Pannonian formations resulted in a new lithostratigraphy of the study area. Moreover, newly published volcanic rock age data were used for calibration of biostratigraphy. The overall age span of the sedimentary fill is occupied only by late Badenian–Sarmatian (Serravallian) to Pannonian (Tortonian–Messinian) strata: 1) the basal alluvial sediments of the newly defined Zlaté Moravce Formation; 2) late Badenian–Sarmatian (Serravalian) marine sediments of the Vráble-Pozba Fm., connected with tectonic opening of the depression; 3) Pannonian (Tortonian) coarse grained sediments of the Nemčiňany Fm. with an erosional base; 4) Pannonian (Tortonian–Messinian) predominantly fine-grained, basin floor to slope Ivanka Fm., sandy deltaic Beladice Fm. and predominantly muddy, alluvial Volkovce Fm. In the middle Miocene provenance is situated in Paleozoic sequences and Neogene volcanic rocks occurring currently in the NE. During the late Miocene, provenance is changed to the NNW (Tribeč Mts.), although the transport from the NE also remained.

Towards better correlation of the Central Paratethys regional time scale with the standard geological time scale of the Miocene Epoch

Abstract Depositional sequences originating in semi-enclosed basins with endemic biota, partly or completely isolated from the open ocean, frequently do not allow biostratigraphic correlations with the standard geological time scale (GTS). The Miocene stages of the Central Paratethys represent regional chronostratigraphic units that were defined in type sections mostly on the basis of biostratigraphic criteria. The lack of accurate dating makes correlation within and between basins of this area and at global scales difficult. Although new geochronological estimates increasingly constrain the age of stage boundaries in the Paratethys, such estimates can be misleading if they do not account for diachronous boundaries between lithostratigraphic formations and for forward smearing of first appearances of index species (Signor-Lipps effect), and if they are extrapolated to whole basins. Here, we argue that (1) geochronological estimates of stage boundaries need to be based on sections with high completeness and high sediment accumulation rates, and (2) that the boundaries should preferentially correspond to conditions with sufficient marine connectivity between the Paratethys and the open ocean. The differences between the timing of origination of a given species in the source area and timing of its immigration to the Paratethys basins should be minimized during such intervals. Here, we draw attention to the definition of the Central Paratethys regional time scale, its modifications, and its present-day validity. We suggest that the regional time scale should be adjusted so that stage boundaries reflect local and regional geodynamic processes as well as the opening and closing of marine gateways. The role of eustatic sea level changes and geodynamic processes in determining the gateway formation needs to be rigorously evaluated with geochronological data and spatially-explicit biostratigraphic data so that their effects can be disentangled.