A late Burdigalian bathyal mollusc fauna from the Vienna Basin (Slovakia)
This is the first record of a bathyal mollusc fauna from the late Early Miocene of the Central Paratethys. The assemblage shows clear affinities to coeval faunas of the Turin Hills in the Mediterranean area and the Aquitaine Basin in France. The overall biostratigraphic value of the assemblage is hard to estimate due to the general very poor knowledge of Miocene bathyal faunas. Several species, however, are known from deep water deposits of the Middle Miocene Badenian stage as well. This implies Early Miocene roots of parts of the Middle Miocene deep water fauna and suggests a low turnover for bathyal mollusc communities at the Early-Middle Miocene boundary. The nassariid gastropod Nassarius janschloegli Harzhauser nov. sp. and the naticid gastropod Polinices cerovaensis Harzhauser nov. sp. are introduced as new species.
Integrated high-resolution stratigraphy of a Middle to Late Miocene sedimentary sequence in the central part of the Vienna Basin
In order to determine the relative contributions of tectonics and eustasy to the sedimentary infill of the Vienna Basin a high-resolution stratigraphic record of a Middle to Late Miocene sedimentary sequence was established for a well (Spannberg-21) in the central part of the Vienna Basin. The well is located on an intrabasinal high, the Spannberg Ridge, a location that is relatively protected from local depocentre shifts. Downhole magnetostratigraphic measurements and biostratigraphical analysis form the basis for the chronostratigraphic framework. Temporal gaps in the sedimentary sequence were quantified from seismic data, well correlations and high-resolution electrical borehole images. Stratigraphic control with this integrated approach was good in the Sarmatian and Pannonian, but difficult in the Badenian. The resulting sedimentation rates show an increase towards the Upper Sarmatian from 0.43 m/kyr to > 1.2 m/kyr, followed by a decrease to relatively constant values around 0.3 m/kyr in the Pannonian. The sequence reflects the creation of accommodation space during the pull-apart phase of the basin and the subsequent slowing of the tectonic activity. The retreat of the Paratethys from the North Alpine Foreland Basin during the Early Sarmatian temporarily increased the influx of coarsergrained sediment, but eventually the basin acted mostly as a by-pass zone of sediment towards the Pannonian Basin. At a finer scale, the sequence exhibits correlations with global eustasy indicators, notably during the Sarmatian, the time of greatest basin subsidence and full connectivity with the Paratethyan system. In the Pannonian the eustatic signals become weaker due to an increased isolation of the Vienna Basin from Lake Pannon.
Decapod crustaceans from the Ottnangian (middle Burdigalian, Lower Miocene) of the Western and Central Paratethys remain poorly known. In this study, we review and re-describe mud shrimps (Jaxea kuemeli), ghost shrimps (Gourretia sp., Calliax michelottii) and brachyuran crabs of the families Leucosiidae, Polybiidae and Portunidae. A dorsal carapace of the genus Calliax is reported for the first time in the fossil record. Re-examination of the type material of Randallia strouhali (Leucosiidae) and Geryon ottnangensis (Geryonidae) resulted in a transfer of these species into Palaeomyra (Leucosiidae) and Liocarcinus (Polybiidae), respectively. Achelous vindobonensis, originally described as a chela of a portunid crab, probably belongs to a member of Polybiidae and is provisionally treated as Liocarcinus sp. Only two species, J. kuemeli and C. michelottii, are also known from the Karpatian, the succeeding Paratethyan stage. In most cases, the decapod assemblages of the Ottnangian consist of rather shallow-water taxa whereas the assemblages of the Karpatian consist of deep-water taxa from the middle and outer shelf. The Central Paratethyan assemblages show similarities in genus composition to the Proto-Mediterranean and recent Indo-Pacific regions. Gourretia sp. represents the earliest occurrence of the respective genus in the fossil record. The Oligocene–Early Miocene appearance of Palaeomyra and Liocarcinus in the circum-Mediterranean implies that sources of present-day diversity hotspots in the Indo-Pacific trace to the Western Tethys (as for other decapod genera), although coeval decapod assemblages in the Indo-Pacific remain poorly known.
The present work displays the first detailed taxonomic study on the freshwater gastropod fauna of the Upper Miocene Lake Turiec. Apart from several mentions of species and genus names in the literature, the mollusc fauna has been poorly studied up to now. Some of the cited genera implied peculiar paleobiogeographic relationships, urging a taxonomic investigation to either prove or revise such arising claims. Variable degrees of preservation, however, limited the possibility to identify all the fossils at species level. The fauna includes at least ten species, of which five turned out to be new to science. Four of those were sufficiently well preserved to be described as new species, namely Viviparus pipiki Neubauer & Harzhauser nov. sp., Melanopsis glaubrechti Neubauer & Harzhauser nov. sp., Tournouerina turiecensis Neubauer & Harzhauser nov. sp., and Radix kovaci Neubauer & Harzhauser nov. sp. Additionally, the new genus Popovicia Neubauer & Harzhauser nov. gen. is introduced for the primary homonym Metohia Popović, 1964 non Absolon, 1927. Most importantly, this taxonomic study revises many of the names cited in the literature and proves most of the alleged paleobiogeographic relationships wrong. The only biogeographic and stratigraphic surprise is the record of Popovicia cf. compressa, a species described from lower Pliocene deposits of the Metohia Basin in Kosovo. The majority of the fauna, however, has only been documented for the Turiec Basin, once more confirming the high degree of its endemicity. The faunal relationships indicate a latest Middle to early Late Pannonian (Middle to Late Tortonian) age, which is in agreement with available age models.
This paper describes the section and fossil content of a former gravel pit in the Eastern Styrian Basin (SE Austria), which exposes sediments of a fluvial system, ranging from within channel to overbank environments. A predominately terrestrial gastropod fauna of 15 species so far, was recovered from a palaeosol formed in a moist and vegetated, floodplain or abandoned channel. Up-section, a shallow freshwater pond/lake developed within the floodplain, settled by fishes, molluscs and ostracods. By integrating regional geological and biostratigraphical data derived from the terrestrial gastropod fauna as well as from the other recovered biota, these strata are of late middle Miocene (late Sarmatian s.str.) age. Hence, this fossil site provides a rare insight into the terrestrial habitats in the hinterland of the Sarmatian Sea and their biota, which are otherwise barely known in Central Europe.
Upwelling conditions in the Early Miocene Central Paratethys Sea
Evidence for regional upwelling conditions in the Central Paratethys Sea is presented for mid-Burdigalian (early Ottnangian) times. The oceanographic phenomenon is detected in clay-diatomite successions along the steep escarpment of the Bohemian Massif in the eastern North Alpine Foreland Basin. Interpretations are based on a multiproxy data-set including published sedimentological and paleontological data, newly performed stable isotope measurements (δ18O, δ13C) of foraminifers and bulk sediment samples, and analyses of dinoflagellate cyst assemblages. The revealed stable isotope values of planktonic foraminifers point to upwelling: low δ13C values indicate strong mixing of surface waters with rising nutrient-rich waters, high δ18O values reflect cool sea surface temperatures (SST). Temperature calculations give SSTs ranging from 10-14 °C. Cool SSTs and high productivity are additionally supported by bulk sediment analyses. Assemblages of dinoflagellate cysts indicate a distal-shelf environment with nutrient-rich waters. Westerly winds and tidal currents are discussed as potential driving forces behind the local upwelling event. As mid-Burdigalian geography favoured strong current patterns in the Central Paratethys as documented in the sedimentary record from the Rhône Basin to Hungary upwelling might have been a more common phenomenon in this epicontinental sea than currently known.
Although decapod crustaceans of the Central Paratethys were diverse during the Badenian (Langhian-Early Serravallian), a dramatic drop in their diversity occurred at the boundary with the Sarmatian. A crab Mioplax socialis is one of the few decapods reported from the Lower Sarmatian (Mohrensternia Zone) of the Paratethys. Until now, this species has been known from only a handful of specimens from Austria, Croatia and Bulgaria (Central Paratethys), and its systematics and ecology remain poorly known. Here, on the basis of new specimens from the Sarmatian tuffitic clays of the Stretava Formation (Skároš, Eastern Slovakia) we confirm that this species belongs to the subfamily Chasmocarcininae. The diagnostic characters of the male sternum that allow this classification are reported for the first time. The molluscan assemblage co-occurring with M. socialis demonstrate that this species tolerated conditions with variable salinity. Its tolerance of a broad range of salinity regimes may thus explain its survival across the Badenian-Sarmatian extinction event. Preservation of near-complete and fully articulated individuals of M. socialis suggests calm conditions and short residence times on the sediment-water interface.
The Sarmatian sedimentary record of the Borod Depression (eastern Pannonian Basin) consists of a marine sequence with continental influence. The investigated section, located near Vârciorog, was biostratigraphically and paleoenvironmentally analysed. The micro- and macrofossil assemblages include dasycladaceans, characeans, foraminifera, molluscs, polychaetes, ostracods, crabs, bryozoans, fish and vertebrate remains, which are characteristic for a shallow marine setting with local transitions to continental facies. The microfossil assemblages are characteristic for the Elphidium reginum Zone and Mohrensternia Zone of the early Sarmatian (Serravallian). The succession of populations correlates with the sedimentological trend, allowing the separation of several genetic units. The relative sea-level changes and the progradational trend from the top of the section suggest active tectonics in the hinterland (Apuseni Mountains). The shallow seas surrounding the emerging islands (Apuseni Mountains) provided the connections between the Pannonian and Transylvanian basins during the early Sarmatian
The formations underlying the Neogene infill of the Vienna Basin are still poorly documented. Until now correlation of subsurface lithostratigraphic units with those of the Rhenodanubian nappe system and the Magura nappe system, outcropping at the basin margins, has been based on extrapolations. A recent drilling campaign in the Bernhardsthal oil field of the northern Vienna Basin in Austria reached the pre-Neogene basement and provided cuttings for biostratigraphic and paleoecological analyses. Based on these data, acquired by using detailed micro- and nanno-paleontological analyses, a Lutetian age (middle Eocene) and a bathyal depositional environment for the Flysch of the Harrersdorf Unit was documented. The lithological similarity of the drilling with the Steinberg Flysch Formation of the Greifenstein Nappe and its Lutetian age suggests, that the middle Eocene part of the Harrersdorf Unit represents a continuation of the Greifenstein Nappe of the Rhenodanubian Flysch, rather than a frontal part of the Rača Nappe of the Magura Flysch as previously thought.
This paper presents a revised sequence stratigraphy for the lower, middle and upper Badenian depositional systems of the Austrian Vienna Basin based on the integration of 3D seismic surveys and well data. The study area in the central and northern part of the Austrian Vienna Basin is covered with 3D seismic data. According to a new sequence stratigraphic framework established in the southern part of the Vienna Basin, the Badenian is subdivided into three 3rd order depositional sequences. For each sequence, paleogeographic maps are created, representing coeval depositional systems within a chronostrati-graphic interval. Lower Badenian sediments of the 1st sequence (Ba1) represent fillings of the pre-Badenian sub-basins with a major change of sediment transport direction. The early stage of the 1st sequence is dominated by subaerial braided river deposits which use two pronounced canyon systems (Mistelbach Canyon and Reinthal Canyon) on the northwestern margin of the Vienna Basin as a bypass zone towards the marine depositional system of the North Alpine-Carpathian Foredeep. The late stage of the 1st sequence reflects the change from subaerial to marine depositional environments with main sediment influx from the west, creating two major eastwards prograding delta systems (Zistersdorf Delta and Mühlberg Delta). Depositional systems of the middle Badenian 2nd sequence (Ba2) reflect the interplay between ongoing extensional fault tectonics and major sea-level changes. Lower Badenian paleo-highs in the northern part are drowned during the 3rd sequence (Ba3), thus the Mühlberg Delta and the Zistersdorf Delta merge into one delta system. During the Ba3 the drowning of the Spannberg Ridge initiates a clockwise rotation of the Zistersdorf Delta. Thus, the former Zistersdorf Delta transforms into the Matzen Delta covering the Spannberg Ridge. Together with the Mühlberg Delta, they represent the last full marine depositional system of the eastward prograding paleo-Danube Delta in the Austrian Vienna Basin.