Vienna Basin Research Articles

A comprehensive assessment of image processing variability in pore structural investigations: Conventional thresholding vs. machine learning approaches

Broad ion beam - scanning electron microscopy (BIB-SEM) is an important technology for quantitative description of pore space and detailed investigation of pore structure in mudstones and shales. To obtain quantitative data from BIB-SEM images, image processing is required. However, the effect of different image processing approaches on the segmentation results has not been well documented yet. Particularly the interpretation of pore boundaries approaching the maximum image resolution can represent a major challenge. This study addresses the variability in image processing by comparing conventional thresholding with advanced machine learning methods and analysing the sensitivity of results to different segmentation. The test dataset consists of large area BIB-SEM maps of 12 Middle Miocene mudstone samples from the Vienna Basin, Austria. Segmentation of pore space and organic matter was performed using the thresholding method in ImageJ and the machine learning-based pixel classification in ilastik. The results show that the selected greyscale thresholding algorithm in ImageJ significantly affected the resolved porosity (1.7% to 2.8% variation) relative to the average total porosity of 4.5%. Compared to ImageJ, ilastik provides comparable results with better efficiency in separating pores from organic matter. However, the obtained pore information is inevitably influenced by variations in boundary delineation and feature identification due to inherent differences in the image processing methods and varying representativeness of image maps themselves. Overall, the study findings highlight the importance of carefully selecting image processing methods and considering their potential impact on the accuracy and reliability of pore characterization in mudstones and shales.

Insights in Hailstorm Dynamics through Polarimetric High-Resolution X-Band and Operational C-Band Radar: A Case Study for Vienna, Austria

Abstract Data from a dual-polarized, solid-state X-band radar and an operational C-band weather radar are used for high-resolution analyses of two hailstorms in the Vienna, Austria, region. The combination of both radars provides rapid-update (1 min) polarimetric data paired with wind field data of a dual-Doppler analysis. This is the first time that such an advanced setup is used to examine severe storm dynamics at the eastern Alpine fringe, where the influence of local topography is particularly challenging for thunderstorm prediction. We investigate two storms transitioning from the pre-Alps into the Vienna basin with different characteristics: 1) A rapidly evolving multicell storm producing large hail (5 cm), with observations of an intense ZDR column preceding hail formation and the rapid development of multiple pulses of hail; and 2) a cold pool–driven squall line with small hail, for which we find that the updraft location inhibited the formation of larger hailstones. For both cases, we analyzed the evolution of different ZDR column metrics as well as updraft speed and size and found that (i) the 90th percentile of ZDR within the ZDR column was highest for the cell later producing large hail, (ii) the peak 90th percentile of ZDR preceded large hailfall by 20 min and highest updraft size and speed by 10 min, and (iii) sudden drops of the 90th percentile of ZH within the ZDR column indicated imminent hailfall. Significance Statement Thunderstorm evolution on the transition from complex terrain into the Vienna basin in northeastern Austria varies strongly. In some instances, thunderstorm cells intensify once they reach flat terrain, while in most cases there is a weakening tendency. To improve our process understanding and short-term forecasting methods, we analyze two representative cases of hail-bearing storms transitioning into the Vienna basin. We mainly build our study on data from a new, cost-efficient weather radar, complemented by an operational radar, lightning observations, and ground reports. Our results show which radar variables could be well suited for early detection of intensification, and how they relate to thunderstorm updraft speeds and lightning activity.

Making the most out of historical cores for geothermal exploration

Abstract During the current trend of the energy transition, many stratigraphic intervals that previously were thought as uneconomical from an oil and gas business perspective are being re-evaluated for low-carbon energy resource potential such as geothermal. This study presents a case study from the Vienna Basin, Austria, where the Early Badenian Rothneusiedl Formation has been targeted for a re-evaluation, utilizing existing sparse subsurface datasets of vintage quality. The historical cores were subjected to diverse analytical techniques covering sedimentological, petrophysical and thermophysical aspects. These analysis techniques provided the fundamental lithological characteristics and led to the creation of a synthetic conceptual sedimentological log, resultant selection of samples for further analyses, as well as the creation of gross depositional environment maps. The reservoir and thermal properties guided by the core-based lithofacies were required for evaluating the feasibility of the target strata. Overall, the limited and historical cores provided significant and robust data that proved crucial for assessing uncertainties and identifying sub-areas of the Vienna Basin for harnessing geothermal energy. This study demonstrates an important case example of the utilization of historical cores to their maximum potential and reiterates the value of core-derived data amongst digital technologies of the twenty-first century.

U–Pb zircon age and mineralogy of the St Georgen halloysite tuff shed light on the timing of the middle Badenian (mid-Langhian) transgression, ash dispersal and palaeoenvironmental conditions in the southern Vienna Basin, Austria

A geochronological study of the St Georgen tuff, favourably positioned within the Middle Miocene marine succession of the Vienna Basin, is essential to our understanding of the timing of the middle Badenian transgression. We report here new data on the separated zircon U–Pb ages/phase chemistry and the clay mineralogy of altered tuffs and then use these data to infer the provenance of the tephra and the palaeoenvironmental conditions. The ages of the tuff range between 15.78 ± 0.27 and 14.36 ± 0.31 Ma, with a weighted mean age of 14.59 ± 0.2 Ma. This defines the onset of the second Badenian transgression in the Central Paratethys region, which was the strongest transgression in the entire Miocene record of the Vienna Basin. The compositional and temporal relationships between the tuff and the neighbouring volcanism suggest that the Harsány eruption in the central Pannonian Basin is the most plausible source region for the tephra. West- and SW-directed tropospheric trade winds or easterlies were responsible for the transport of the Harsány tephra to its present location. The prevalence of halloysite, in addition to post-depositional alteration reactions (glass–smectite–halloysite and kaolinite–halloysite) suggest the fallout of tephra in a very shallow sea, which may have been affected by seasonal wetting and drying cycles at the onset of ash deposition. Supplementary material: Halloysite mineralogy, global geochemistry and U-Pb zircon age data are available at https://doi.org/10.6084/m9.figshare.c.6294944

Geoarchaeological remote sensing prospection of Miocene limestone quarries in the hinterland of Roman Carnuntum and Vindobona (Vienna Basin, Austria)

Abstract We have documented quarries in Miocene limestone in the Vienna Basin (Austria), Hundsheim Mountains, Leitha Mountains and Rust Hills in high-resolution airborne laser scanning data and orthophotos aiming for a diachronic quarry inventory since the Roman period. The study region was divided into 6 quarry regions and the quarries of the whole study area as well as each separate region were analyzed concerning different rock types, mean, minimum and maximum quarry area and development in the different maps. Age information have been sought from historical maps, historical photography and paintings as well as quarry face graffiti. In total, 658 quarries, possible quarries and shallow quarries have been outlined in the detailed digital terrain models, which were compared with 453 quarries indicated in four generations of historical maps between the years 1754 to 1872. The numbers of quarries are generally low in the Walter map (1754–1756), the First Military Survey (1773–1785) and Second Military Survey (1809–1846) but increase tremendously in the maps of the Third Military Survey (1872–1873). Most old quarries were quarried also in subsequent periods, commonly destroying virtually all pre-existing traces. According to our results two types of quarries represent highly interesting targets for more detailed studies in the search for Roman quarries: (i) areas in historical maps with suspicious uneven terrain, which have never been outlined as quarries and areas that have been mapped as “old quarries” – especially in the Third Military Survey; examples represent areas northwest and west of Pfaffenberg in Bad Deutsch-Altenburg (Lower Austria), “Gruibert” in Winden am See (Burgenland) and “Hoher Berg” in Stotzing (Burgenland); (ii) Shallow quarries, which neither appear in historical maps nor in the mining archive of the Geological Survey of Austria like the one from the saddle between Pfaffenberg and Hundsheimer Berg.

The temporal evolution of seismicity and variability of b-values along the Vienna Basin Transfer Fault System

Abstract The Vienna Basin Transfer Fault System (VBTFS) is the most active fault system in the region between the Eastern Alps, the western Carpathians and the Pannonian Basin. The spatial and temporal distribution of earthquakes along the fault system shows a heterogeneous pattern including a long-time decay of seismicity at the northern part of the VBTFS, which was interpreted to result from a long aftershock sequence subsequent to the 1906 Dobrá Voda earthquake (M=5.7). In this paper we investigate if other segments of the VBTFS display similar long-term declines of seismicity that might indicate long aftershock sequences following strong, yet unrecorded, earthquakes in historical times. In order to analyse the distribution of seismicity, the VBTFS is divided into arbitrary segments of about 50 km length each. The segments are chosen to overlap each other to avoid missing information from neighbouring segments due to arbitrarily selected segment boundaries. For each segment we analyse the temporal evolution of seismicity and calculate the parameters of the corresponding Gutenberg-Richter (GR) relation. The temporal seismicity patterns revealed from the segments covering the Dobrá Voda area confirm the protracted aftershock sequence following the 1906 earthquake. All but one of the other segments do not show temporal changes of seismicity comparable to the long-term Dobrá Voda aftershock sequence. Seismicity patterns, however, include short-term Omori-type aftershocks following moderate earthquakes such as the 2000 Ebreichsdorf earthquake (M=4.8). The segment covering the SW tip of the VBTFS revealed a 200 years long gradual decrease of the largest observed magnitudes starting with the 1794 Leoben (M=4.7) earthquake. The 1794 event is the oldest earthquake listed in the catalogue for the region under consideration. It therefore remains open if the recorded decay of seismicity results from the 1794 event, or a stronger earthquake before that time. The latter is corroborated by the low magnitude of the 1794 earthquake which would typically not be considered to cause long aftershock sequences. GR a- and b-values, calculated for the individual segments, vary significantly along the VBTFS. Values range from 0.47 to 0.86 (b-values) and 0.81 to 2.54 (a-values), respectively. Data show a significant positive correlation of a- and b-values and a coincidence of the lowest b-values with fault segments with large seismic slip deficits and very low seismicity in the last approximately 300 years. These parts of the VBTFS were previously interpreted as “locked” fault segments, which have a significant potential to release future strong earthquakes, in spite of the fact that historical and instrumentally recorded seismicity is very low. We find this interpretation corroborated by the low b-values that suggest high differential stresses for these fault segments.

Nitrate isotopes reveal N-cycled waters in a spring-fed agricultural catchment

ABSTRACT Nitrate stable isotopes provide information about nitrate contamination and cycling by microbial processes. The Fischa-Dagnitz (Austria) spring and river system in the agricultural catchment of the Vienna basin shows minor annual variance in nitrate concentrations. We measured nitrate isotopes (δ 15N, δ 18O) in the source spring and river up to the confluence with the Danube River (2019–2020) with chemical and water isotopes to assess mixing and nitrate transformation processes. The Fischa-Dagnitz spring showed almost stable nitrate concentration (3.3 ± 1.0 mg/l as NO3 –-N) year-round but surprisingly variable δ 15N, δ 18O-NO3 – values ranging from +5.5 to +11.1‰ and from +0.5 to +8.1‰, respectively. The higher nitrate isotope values in summer were attributed to release of older denitrified water from the spring whose isotope signal was dampened downstream by mixing. A mixing model suggested denitrified groundwater contributed > 50 % of spring discharge at baseflow conditions. The isotopic composition of NO3 – in the gaining streams was partly controlled by nitrification during autumn and winter months and assimilation during the growing season resulting in low and high δ 15N-NO3 – values, respectively. NO3 – isotope variation helped disentangle denitrified groundwater inputs and biochemical cycling processes despite minor variation of NO3 – concentration.

Marine facies differentiation along complex paleotopography: an example from the Middle Miocene (Serravallian) of Lower Austria

In the area of Bad Deutsch-Altenburg (Hainburg Mountains, Lower Austria) a Middle Miocene transgression over Mesozoic basement was explored in the course of the Danube power plant project “Hainburg”. The Mesozoic basement forms a narrow ridge dipping to the northeast towards the Vienna Basin, covered by various Miocene sediments. The ridge represents a specific paleotopography that required a detailed study with 78 shallow, fully cored drill holes in an area of c. 0.5 km2. Ten drillings were selected for this study based on sedimentary composition and position relative to the Mesozoic ridge. These 10 cores, ranging in drilling depth from 26.5 to 96.4 m, were studied in respect to sedimentology, corallinacean algae, calcareous nannoplankton, foraminifers and ostracodes to reconstruct sediment distribution and paleoenvironment. Sediment distribution clearly shows that the Mesozoic ridge formed a physical barrier with siliciclastics dominating in the SW of the ridge and carbonate sediments prevailing in the NE. Based on biostratigraphy (calcareous nannoplankton, foraminifera, ostracodes, dinoflagellates) the majority of the sediments can be dated to the late Badenian (early Serravallian) only in some drillholes lower Sarmatian (upper Serravallian) sediments were detected. In terms of sequence stratigraphy, the Badenian sediments represent the transgressive and highstand systems tract of 3rd order sequence TB 2.5 (bound by the lowstands Ser 2 and Ser 3), the lower Sarmatian sediments can be correlated to sequence TB 2.6. Carbonate sediments show a wide spectrum of 13 facies which are mostly dominated by coralline algae. According to the relative positions of the drill holes a water depth between 0 and about 50 m can be reconstructed what is supported by the occurrence of the benthic biota. This biota indicates that the sedimentary succession started from the very beginning under full marine conditions. Except of basal conglomerates/breccias water energy conditions were low and turbidity high. Close to the Sarmatian boundary a reduction in salinity and depth may have occurred which is also observed in the Sarmatian sediments. Carbonate sediments and, in particular, larger benthic foraminifers indicate tropical to warm-temperate conditions for the late Badenian of the studied sections. The siliciclastic sediments NW of the Mesozoic ridge reflect riverine input indicated by the occurrence of freshwater ostracodes and characean oogonias. Calcareous nannoplankton and dinoflagellates show a high share of reworking from Upper Cretaceaous and Paleogene sediments.

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.

Middle Miocene (Serravallian; upper Badenian–lower Sarmatian) dinoflagellate cysts from Bad Deutsch-Altenburg, Vienna Basin, Austria

Middle Miocene (Serravallian; upper Badenian–lower Sarmatian) strata recovered in 10 cored boreholes (83 samples) from Bad Deutsch-Altenburg, Vienna Basin, Austria, were analysed palynologically for the first time. The strata belong to the Rabensburg Formation of the Baden Group. The lateral distribution of the boreholes in reference to a Mesozoic ridge makes this area interesting for studying various aspects such as distribution of deposits, stratigraphy and palaeoenvironmental reconstruction. A diverse and well-preserved in situ dinoflagellate cyst association has been identified. Middle Miocene age-diagnostic species including Cannosphaeropsis passio, Cerebrocysta poulsenii, Habibacysta tectata, Labyrinthodinium truncatum, Operculodinium? borgerholtense and Unipontidinium aquaeductum are recorded. Their occurrences allow correlation with dinoflagellate cyst biozonations on a regional scale. Based on the identified dinoflagellate cysts and by correlation with calcareous nannoplankton and ostracods, from the same set of samples, a Serravallian age – corresponding to a late Badenian and early Sarmatian age (regional Paratethys stages) – is confirmed. Reworked (Cretaceous and Paleogene) dinoflagellate cyst assemblages, also well preserved, were recorded abundantly from boreholes HA 521 and HA 573 (south-west of the Mesozoic ridge). In accordance with ostracods, the Badenian–Sarmatian boundary can be traced in the upper part of borehole HA 66 based on an abrupt change in the dinoflagellate cyst assemblages. The upper Badenian strata were deposited in a coastal to inner shelf environment with terrigenous (siliceous sand and clay) and carbonate sediments. The recorded dinoflagellate cysts reflect marine, tropical to warm-temperate climatic conditions. The composition of the recorded dinoflagellate cyst assemblages is very close to that of the Middle Miocene assemblages of the Mediterranean, indicating water exchanges between the Central Paratethys and the Mediterranean during the late Badenian (early Serravallian).

High resolution Late Miocene sediment accommodation rates and subsidence history in the Austrian part of the Vienna Basin

We present the first detailed intra-basin correlation of Upper Miocene deposits in the Austrian part of the Vienna Basin (VB) integrating the most important hydrocarbon fields. Herein, we use a high resolution dataset by separating the Pannonian (= Tortonian) stack into 20 lithostratigraphic units, which allow calculating regional differences in sedimentation rates over a time span of ∼1.6 Ma. During this time span we recognize an initial phase of high lateral variability in thicknesses, reflecting the influence of paleo-topography on deposition during the early Pannonian. The relief difference of about 300 m was rapidly filled by lake marls and delta lobes of the Paleo-Danube. Subsequently, lateral variability in sediment thicknesses declined strongly around 11.0 Ma. At that point the relief was largely sealed, and subsidence became the controlling factor. Our data document a shift of high subsidence rates from the southern VB to the northern VB into three steps, initiated by increased activity of the Steinberg Fault around 10.5–10.4 Ma. Sedimentation rates have been declining during the early Pannonian but reveal a strong pulse in subsidence during the middle Pannonian. The still high sedimentation rates during the late Pannonian indicate persisting extensional tectonics in the VB throughout the Late Miocene and question the prevailing tectonic model of a compressional regime for this time. The lack of uppermost Pannonian deposits in most wells documents a post-Pannonian erosion of about 400 m in large parts of the VB.

Sulfuric acid speleogenesis and surface landform evolution along the Vienna Basin Transfer Fault: Plavecký Karst, Slovakia

Hypogene caves in the Plavecký hradný vrch Hill (Western Slovakia, Central Europe) were formed by waters ascending along faults in fractured Triassic carbonates related to the horst-graben structure at the contact of the Malé Karpaty Mountains and the NE part of the Vienna Basin. The Plavecká jaskyňa and Pec caves mostly contain horizontal passages and chambers with flat corrosion bedrock floors, fissure discharge feeders, wall water-table notches, replacement pockets, as well as a few other speleogens associated with sulfuric acid speleogenesis. The low-temperature sulfuric acid development phases of the Plavecká Jaskyňa are also indicated by the presence of sulfate minerals (i.e., gypsum and jarosite).Subaerial calcite popcorn rims were precipitated from water condensation at the edges of feeding fissures that were still active as thermal vents when the water table dropped. Hydrogen sulfide involved in the sulfuric acid speleogenesis was likely derived from anhydrites and/or hydrocarbon reservoirs with sulfate-saline connate waters in the fill of the adjacent Vienna Basin. It ascended to the surface along deep-rooted sub-vertical fault zones at the contact of the Vienna Basin with neighboring mountains. Three cave levels at 295 to 283 m asl in the Pec Cave, and five levels at 225 to 214 m asl in the Plavecká jaskyňa corresponded to phases of stable local erosional base levels in the bordering part of the Vienna Basin, most likely during periods of strongly decelerated and/or interrupted subsidence. Cave levels separated by vertical differences of only a few meters may also be related to the Pleistocene climatic cycles. The subhorizontal parts of the Pec Cave are probably of late Early Pleistocene age (˃0.99–1.07 Ma?). The two highest levels of the Plavecká jaskyňa developed during the early Middle Pleistocene (˃600 ka). Fine-grained sediments in the passage at 225 m asl with normal magnetic polarity contain jarosite. The middle level of the Plavecká jaskyňa at 220 m asl was formed in the mid-Middle Pleistocene, while the lower and lowermost levels formed in the late Middle Pleistocene (˃270 ka). The water table in the lowermost cave level probably dropped after the tectonic reactivation of the Podmalokarpatská zníženina Depression just in the front of a marginal horst structure of the Malé Karpaty Mountains.

Deltaic systems of the northern Vienna Basin: The lower-middle Miocene conglomerate bodies

Deltaic systems of the northern Vienna Basin: The lower-middle Miocene conglomerate bodies

FISH OTOLITHS AND FORAMINIFERA FROM THE BORSKÝ MIKULÁŠ SECTION (SLOVAKIA, MIDDLE MIOCENE, UPPER BADENIAN, VIENNA BASIN) AND THEIR PALEOENVIRONMENTAL SIGNIFICANCE

Thirty-eight otolith-based species of fishes and 41 foraminifera species have been recorded in the Borský Mikuláš-Vinohrádky section in the upper Badenian deposits in the eastern part of the Vienna Basin, in West Slovakia. Two new species of otoliths are introduced here: Thorogobius antirostratus n. sp. and Gerres mlynskyi n. sp. Among the foraminifera Biasterigerina planorbis and Elphidium crispum associated with other elphidiids, Lobatula lobatula and Cibicides crassiseptatum prevail. Overall, the family of Gobiidae dominate in the assemblage of otoliths (>90 % of specimens). Meso- and epipelagial fishes or diversified gadids and sciaenids are missing. From the molluscs, the first record of Aturia sp. in the Borský Mikuláš section is observed. Otoliths and foraminifera document a normal marine environment of well-aerated shallow water with a depth of 30-50 metres, with muddy to sandy bottoms of marine meadows and plenty of light in the subtropical climatic conditions. Several fish genera (for example Gerres) give evidence for the nearness of reef structures. There are no species (excepting Lesueurigobius vicinalis) in common with the known Lower Serravallian otolith fauna from the Eastern Paratethys. Some species from the Borský Mikuláš-Vinohrádky section can also be found in the Mediterranean Langhian-Serravallian interval and are interpreted as a relic of the lower Badenian (Langhian) fish assemblages.

Engineering Geological Properties of Building Stones from the North-Eastern Part of the Vienna Basin in the Western Carpathians

Engineering Geological Properties of Building Stones from the North-Eastern Part of the Vienna Basin in the Western Carpathians

The Pannonian Plain: Denomination, Definition and Subdivision

The Pannonian Plain is a landscape- and a physico-geographic unit. It encompasses the plain, lowland landscapes of the Pannonian realm. If we follow the Pannonian Plain along the Danube valley, it starts from with Vienna Basin continues downstream till the Iron Gate.
 The Pannonian Plain (Pannon-alföld / Panonska nizija) can be subdivided in six landscape units. The three main units are: the Vienna Basin (Wiener Becken), the Little Alföld (Kisalföld) and the Alföld. The three smaller units have some kind of connections with the Alföld they are the Inner Somogy (Belső Somogy), the western Drava Plain (Donja Podravina) and the Upper Sava Plain (Donja Posavina).
 The Pannonian Plain has no synonyms. the terms Pannonian Basin, Pannonian realm, Pannonian Basin System as well as the Carpathian Basin have different meanings and context.

Late miocene evolution of the Paleo-Danube Delta (Vienna Basin, Austria)

The first deltas of the Paleo-Danube formed around 11.5 Ma ago along the northwestern margin of the Vienna Basin, during a lowstand of Lake Pannon. We present a detailed description of the depositional architecture of five individual lobes of these deltas in the Austrian part of the central Vienna Basin based on the integration of 3D seismic surveys and well-log data, covering an area of about 600 km2. Based on geometry, steep clinoforms and the development of beach ridges, the delta is classified as mostly river-dominated with significant influence of wave-reworking processes. The development and shifts of individual lobes suggest a stepwise northward movement of the delta system, which is discussed in relation to a stepwise activity of regional fault systems. True vertical depth measurements between topset and bottomset deposits document a decrease of lake water depth from about 180 m during the early phase of delta formation at 11.5 Ma down to about 100 m during its mature phase. A major lake level rise of Lake Pannon around 11.3 Ma caused the flooding of the margins of the Vienna Basin, resulting in back stepping of fluvial deposits into the North Alpine Foreland Basin, which led to the termination of delta deposition in the study area. The Paleo-Danube delta of the Vienna Basin is comparable in many ways to the Holocene to modern Danube delta, located in the Black Sea. Size, sediment volume and speed of progradation of the lobes, however, indicate, that this primeval delta was distinctly smaller than its modern successor and had a much smaller sediment load.

The Impact of Clay Minerals on the Building Technology of Vernacular Earthen Architecture in Eastern Austria

The vernacular architecture in many regions in Eastern Austria was characterized by the use of unfired clay, at least until the 19th century, and in some areas until the 20th century. Farmhouses and associated farm buildings, such as storage buildings or press houses for the production of wine and cider, were erected using different earth construction techniques. The study area stretches from the Weinviertel, a region located in the province of Lower Austria in the north-east of Austria, to the Burgenland, a region located in the south-east of Austria, which belonged to Western Hungary until 1921. From a geological point of view, in the east of Austria—in the Vienna Basin and the Molasse Zone—huge areas of Tertiary clay are covered with loess deposits, which is the best-known basic material used in local earth-building traditions. A core question in the research on vernacular earthen heritage focuses on the impact of the geological conditions in Eastern Austria on the local earth-building techniques. The mineralogical composition of the different clays had an impact on the local building techniques. From a material-culture point of view, research on the relationship between the mineralogical properties of clay resources and local building techniques sheds light on the factors which influenced the evolution of certain vernacular building features. Tertiary clays and loess from the Pleistocene favoured the making of earth lumps, cob walls and adobe bricks over the whole Eastern Austrian region. Contrarily, regions in Burgenland with a high amount of gravel preferred, by tradition, to make walls by ramming. The clay mineral smectite acts as a binding agent in earth-building techniques over the whole investigated region—Weinviertel, Burgenland and Western Hungary.

Collapse wedges in periglacial eolian sands evidence Late Pleistocene paleoseismic activity of the Vienna Basin Transfer Fault (western Slovakia)

Studies of seismically triggered deformations in the depositional record contribute significantly to our knowledge of earthquake recurrence over geological time. This paper describes soft sediment deformation structures preserved in a periglacial Upper Pleistocene succession of eolian sand in the eastern Vienna Basin, Central Europe. The strata were formed dominantly by wind ripples migrating across a sand sheet, less frequently by deposition of fine-grained sand and silt from suspension during decreased wind speed and by small-scale eolian dunes. Most prominent deformations observed are collapse wedges, which are interpreted as being formed along dilatational fractures. Further detected deformations include chaotically disturbed strata, folded strata, and a pop-up structure caused by sliding. The tensile fractures are oriented systematically in a prevailing N–S direction, perpendicular to the W–E extension suggested for the transtensional Vienna Basin Transfer Fault, which underlies the study area. Repeated seismic shock is identified as the trigger of the deformations. The mechanism of deformation implies some degree of cohesion within the deformed strata, and this may be attributed to seasonal frost and the presence of vadose water within the upper levels of the sediment. These deformations appear periodically, in 25 distinct horizons of strata internally deformed by collapse wedges, and in 40 horizons if deformation both by collapse wedges and/or chaotically disturbed beds is considered. The vertical distribution of deformations allowed the calculation of the recurrence periods of earthquakes with the use of a Bayesian age-depth model; this, in turn, was based on seven OSL ages. The calculation yielded mean recurrence periods of ca. 100 years, though this figure is biased by a relatively high degree of uncertainty in the dating and in the age-depth model. Even with this caveat, the present study reveals the underexplored potential of periglacial eolian deposits to preserve paleoseismological signals.

Cretaceous biostratigraphy and lithostratigraphy of the Glinzendorf Syncline based on well Gänserndorf UeT3 (Vienna Basin, Austria)

Abstract The 2200 m thick Cretaceous units of well Gänserndorf UeT3 have been biostratigraphically analyzed based on cuttings from 3210 m to 5140 m. The deposits from the Tirolic Glinzendorf Syncline (a part of the buried Northern Calcareous Alps) can be largely correlated with the Lower Gosau Subgroup of the Grünbach Syncline. An exception is the basal unit, which has no equivalent in the Grünbach Syncline. This lower unit is subdivided into a non-marine lower and a largely marine upper part. No age constraints are available for the lower part, whereas the upper part has a possible age range from middle Turonian to Coniacian. For this unit, which is documented for the first time from the Glinzendorf Syncline, we propose Glinzendorf Formation as new lithostratigraphic term. The Glinzendorf Fm. is overlain by the Grünbach Fm., which is intercalated by a thick unit of conglomerates. These are interpreted as equivalents of the Dreistetten Conglomerate Mb. The calcareous nannofossils of these units suggest a latest Santonian to early Campanian age. Non-marine conditions prevailed during deposition of the Grünbach Fm., but marine incursions are indicated for parts of the Dreistetten Conglomerate Mb. The top of the Grünbach Fm. is formed by an about 50-m-thick unit of coal, rich in Characeae oogonia, which, together with the Dreistetten conglomerates serve as marker layer for correlation with the outcrops in the Grünbach Syncline. The Grünbach Fm. is overlain by marls and silty shales of the Piesting Fm. for which a late Campanian and Maastrichtian age is documented. Marine conditions predominated during this interval. The topmost unit in well Gänserndorf UeT3 is overthrusted on the Maastrichtian Piesting Fm. and represents Campanian sandstones and conglomerates of the Grünbach Fm. This Gänserndorf Thrust is detected and biostratigraphically constrained for the first time.