Volume 113 (2020): Issue 2 (June 2020)

This work describes the Freyenstein Fault System, which extends over 45 km in the southeastern part of the Bohemian Massif (Lower Austria). It represents a ductile shear zone overprinted by a brittle fault located at the eastern edge of the South Bohemian Batholith towards the Moldanubian nappes. It affects Weinsberg- and a more “fine-grained” granite, interlayered aplitic granite and pegmatite dikes as well as paragneiss of the Ostrong Nappe System. The ductile shear zone is represented by approximately 500 m thick greenschist-facies mylonite dipping about 60° to the southeast. Shear-sense criteria like clast geometries, SCC`-type shear band fabrics as well as abundant microstructures show top to the south/ southsouthwest normal shearing with a dextral strike-slip component. Mineral assemblages in mylonitized granitoid consist of pre- to syntectonic muscovite- and biotite-porphyroclasts as well as dynamically recrystallized potassium feldspar, plagioclase and quartz. Dynamic recrystallization of potassium feldspar and the stability of biotite indicate upper green-schist-facies metamorphic conditions during the early phase of deformation. Fluid infiltration at lower greenschist-facies conditions led to local sericitization of feldspar and synmylonitic chloritisation of biotite during a later stage of ductile deformation. Finally, a brittle overprint by a north-south trending, subvertical, sinistral strike-slip fault that shows a normal component is observed. Ductile normal shearing along the Freyenstein Shear Zone is interpreted to have occurred between 320 Ma and c. 300 Ma. This time interval is indicated by literature data on the emplacement of the hostrock and cooling below c. 300°C inferred from two Rb-Sr biotite ages measured on undeformed granites close to the shear zone yielding 309.6 ± 3 Ma and 290.9 ± 2.9 Ma, respectively. Brittle sinistral strike-slip faulting at less than 300°C presumably took place not earlier than 300 Ma. Early ductile shearing along the Freyenstein Fault System may be genetically, but not kinematically linked to the Strudengau Shear Zone, as both acted in an extensional regime during late Variscan orogenic collapse. A relation to other major northeast-southwest trending faults of this part of the Bohemian Massif (e.g. the Vitis-Pribyslav Fault System) is indicated for the phase of brittle sinistral movement.

Foraminiferal assemblages from Upper Jurassic Klentnice beds in Lower Austria are described and analysed. The early late Tithonian assemblages comprise 75 foraminiferal taxa and simple diversities reach up to 31 taxa per sample, pointing to comparatively high diversity in general. The assemblages are dominated by lenticulinid forms (Genera Astacolus, Lenticulina, Saracenaria, Vaginulinopsis). Trocholina is the most common genus and present in all samples. Other frequent genera are Marssonella and Neobulimina. Co-occurrence of epifaunal (grazing) herbivores and epi- to deep infaunal active deposit feeders points to mixed assemblages from different sources and supports the concept of turbiditic systems as prevailing sedimentary regimes in the basinal setting.

For the first time, a concise lithostratigraphic scheme for the lower and middle Miocene (Ottnangian – Badenian) of the northern and central Vienna Basin is proposed, which is based on the integration of core-material, well-log data and seismic information from OMV. For all formations and members type sections are proposed, geographic distribution and thickness are provided, typical depositional environments and fossils are described and age constraints are discussed. This time frame allows for a more reliable calculation of sedimentation rates. This in turn might be important for the reconstruction of the tectonic history of the Vienna Basin as we do not see fundamental differences between the piggy-back stage and the subsequent pull-apart regime. Following lithostratigraphic units are formalized herein and/or are newly introduced: Bockfließ Formation (Ottnangian), Aderklaa Formation, Gänserndorf Member and Schönkirchen Member (Karpatian), Baden Group, Rothneusiedl Formation and Mannsdorf Formation (lower Badenian), Auersthal Formation, Matzen Formation, Baden Formation, Leitha Formation (middle Badenian) and Rabensburg Formation (upper Badenian).

Carnian metapelites from the southeastern segment of the Mürzalpen Nappe (Northern Calcareous Alps, Eastern Alps) were heated to 280-310 °C, estimated by Raman spectroscopy of carbonaceous material (RSCM). This temperature range is correlated to a Color Alteration Index of 5.0-6.5, determined on conodonts from adjacent Anisian to Norian carbonates. Average RSCM temperatures estimated on the conodonts are biased towards higher temperatures. The spectral characteristics of the conodont apatite suggest a composition altered during progressive recrystallization, influencing the band parameters of the included carbonaceous matter. Consequently, accurate conodont RSCM thermometry needs an assessment of apatite alteration.

The Kellerjoch forms a small isolated massif at the northernmost rim of the central Eastern Alps of Tyrol and shows a number of geomorphological features of glacial and periglacial origin. Mapping yields evidence of two local glaciations postdating the Last Glacial Maximum. Using a simple glaciological approach the palaeoglaciers related to these events were reconstructed. The older glaciation yields an equilibrium line altitude (ELA) ranging from 1660 m for the maximum extent to 1800 m a.s.l. for the innermost moraine. For the younger glaciation, ELAs were reconstructed at 1905 m and 1980 m (depending on the reconstruction) for the Kellerjoch palaeoglacier 2, as well as 1870 m and 2060 m a.s.l. for the Proxen palaeoglacier and the Gart palaeoglacier, respectively. A comparison with published data from the Eastern Alps shows that the older glaciation in the Kellerjoch region likely corresponds to the Gschnitz stadial. Low basal shear stresses of the glacier tongues point towards a cold and dry climate, similar to the reconstruction for the Gschnitz type locality at Trins. The younger glaciation cannot unambiguously be assigned to a specific Late Glacial ice advance, but a Younger Dryas age is a distinct possibility.

Deep-neritic sediments of the Eferding Formation (Egerian, Upper Oligocene) of Upper Austria from the Kamig kaolinite quarry revealed minute teeth of the putatively planktivorous shark genus Nanocetorhinus. This is the oldest unambiguous record of this rarely documented genus, which was known so far only from Miocene deposits of Europe, North America and Japan. Based on previous studies, which showed a positive correlation between sediments of nutrient rich waters and plankton blooms with a majority of ichthyoliths of Keasius and Nanocetorhinus, we argue for a filter-feeding and migratory lifestyle of the latter. Thus, it is supposed that Nanocetorhinus migrated seasonally for foraging, in a similar way to the extant basking shark Cetorhinus maximus. This mode of life and the wide paleogeographic distribution of the open marine genus Nanocetorhinus requires a deep and fully marine connection between the Paratethys and the Proto-Mediterranean Sea during late Oligocene times, which might have been established via the Slovenian Corridor.

In the course of foundation works in the Dürnstein Castle cervical and front leg bones of a large Bison priscus bull were discovered in fluvial sediments. The small city of Dürnstein with its medieval centre is part of the UNESCO Wachau Cultural Landscape and is built mainly on Palaeozoic basement rocks. The find location is completely overbuilt, but remnants of fluvial sediments on the bones together with the altitude of the site approximately 17 m above the Danube point to a Middle Pleistocene fluvial aggradation level not younger than ca. 240,000 years, and the maximum age is 400,000 years. The fossil bearing location is interpreted as a small sandy bay of the Pleistocene Danube, protected from later degradation and erosion. Morphometric comparisons and taphonomic analyses of the bones allow the reconstruction of a scenario in which the bison probably had drowned in a flood and its carcass was buried quickly before destruction by scavengers or erosion. The study includes a comparison with bison specimens of an unpublished small megafaunal assemblage from adjacent Krems-Kreuzbergstraße. Processing marks on parts of these bones point to an anthropogenic Middle Palaeolithic influence and translocation. In addition, a tentative chronological sketch of the regional Bison species succession (B. menneri, B. schoetensacki, B. priscus) from the Early to the Late Pleistocene is presented.

Historical fossil assemblages from the Lower Jurassic to Lower Cretaceous of the Sankt Veit Klippen Unit (SVK) on the western outskirts of Vienna were re-evaluated. Collections of the material from the St. Veit Klippen Unit comprise 3497 specimens. An appropriate nomenclature was used, and the taxonomy was partly revised. Historical collections from Franz Toula (1845–1920) and Friedrich Trauth (1883–1967) were investigated in the collections of the Natural History Museum Vienna, the Geological Survey Vienna, the Department of Geology and the Department of Palaeontology (both University Vienna). Additional collections were studied in the district museums Hietzing (13^th district Vienna) and Liesing (23^rd district Vienna), in the district municipal office of Hietzing and in the Wienerwald Museum (Eichgraben, Lower Austria). The study area is situated in the easternmost part of the St. Veit Klippen Unit in the Wienerwald (Vienna Woods), part of the 13^th Viennese district Hietzing. New data allowed a revision of the biostratigraphy of several lithological units of the SVK. Two main fossil complexes could be distinguished: 1) the Hohenauer Wiese assemblage from the wildlife park Lainz (= “Lainzer Tiergarten”) and 2) the Glasauer quarry assemblage from St. Veit.