Austrian Journal of Earth Sciences Feed

Thrust-related folding in early burial: an example from the Upper Jurassic Oberalm Formation, Northern Calcareous Alps, Eastern Alps, Austria

Tue, 13 Oct 2026 00:00:00 GMT

Large-scale fault-related folds are typically studied using reflection seismic or scattered, limited quality, outcrop data. The nature of both data types tends to obscure the information from the structurally most complex areas, particularly fold forelimbs. Additionally, in fold and thrust belts, syn-tectonic deposits are often deformed shortly after deposition, resulting in the co-occurrence of both tectonic and mass-transport-related deformation structures. This is the case in the Northern Calcareous Alps, where the Alpine orogeny has produced complex systems of folds and thrusts along with associated syn-tectonic deposits. Here, we focus on a Late Jurassic siliceous to calciturbiditic succession of Tauglboden Fm and Oberalm Fm, which infill a basin developed in front of a salt-fed thrust: the Grabenbach thrust. Our aim is to characterize deformation structures observed in these formations in the immediacy and in areas surrounding the outcrop of the thrust, to discriminate between tectonic and mass-transport-related deformation structures. We conducted detailed structural mapping, generated photogrammetric models and collected samples, analyzing geometries at scales ranging from millimeters to decameters to assess the deformation conditions and mechanisms. We identify segments of strongly localized deformation, including complex folding patterns, within broad domains of a mostly undeformed, flat-lying succession. We interpret these segments as parts of large scale anticlines developed in the hanging walls of thrusts. Our observations highlight the importance of a multiscale approach to strain analysis in compressional settings. Moreover, our study has implications for the rates of consolidation in carbonate-rich rocks and for deformation mechanisms in such systems.

2-D S-velocity and radial anisotropy across the southern Vienna Basin from nodal probabilistic ambient noise tomography

Sun, 20 Sep 2026 00:00:00 GMT

During summer 2025, we deployed 140 5-Hz geophones along a profile running from the foothills of the eastern Alps to the Danube basin. Using ambient noise interferometry, we extract Rayleigh- and Love-wave dispersion curves at short periods (0.8–5 s) and develop a high-resolution radially anisotropic shear wave velocity model of the southern Vienna basin. The isotropic shear-wave velocity model reveals the Neogene sediments and the sedimentary units of Northern Calcareous Alps (NCA). We also map a normal fault controlling the shape of the western edge of the basin. Moreover, we find that the anisotropic structure of the southern Vienna basin is characterized by two distinct layers. The upper 1–1.5 km exhibits weakly negative to weakly positive radial anisotropy, whereas deeper levels are marked by strong positive anisotropy. We interpret the shallow negative anisotropy as reflecting the presence of vertically oriented fractures. Beneath the Neogene Basin, the NCA nappe stack displays strong positive anisotropy, consistent with its thin-skinned, low-angle thrust architecture. In contrast, where the NCA crops out to the northwest, the anisotropic signature is weaker and locally reversed.

New insights into the Cambrian to Permian evolution of the Austroalpine basement units of the Schladming Crystalline by UPb zircon geochronology and granitoid geochemistry

Wed, 26 Aug 2026 00:00:00 GMT

The Austroalpine unit comprises, among others, pre-Variscan and Variscan crustal fragments that were incorporated into several nappe systems during Alpine orogeny. These fragments therefore provide important insights that help fill in gaps in our knowledge regarding pre-Alpine paleogeography, tectonics and related magmatism. U-Pb zircon dating in combination with geochemical whole rock and zircon isotope data of meta-granitoids revealed three distinct pre-Alpine plutonic suites within the Austroalpine Schladming crystalline: (1) the Lignitz Plutonic Suite, (2) the Untertal Plutonic Suite and (3) the Eisenhut Plutonic Suite.The mostly fine grained, highly fractionated meta-granitoids of the Lignitz Plutonic Suite have U-Pb ages ranging from 480.1 ± 6.4 to 501.2 ± 6.6 Ma and mean ƐHf(t) values between 6.8 and 11.2. The Hf-isotopes partly hint to a mantle source with different degrees of crustal material assimilation during magma ascent. This suite is highly differentiated showing met- to peraluminous, calc-alkalic character. A suitable setting for this suite is an active margin along northern Gondwana during the Ceneric orogeny. The meta-granitoids to meta-granodiorites of the Untertal Plutonic Suite have U-Pb zircon ages between 350.4 ± 4.8 Ma and 370.4 ± 4.9 Ma and ƐHf(t) values between 2.6 and 3.9. Ordovician ages and high ƐHf(t) values of zircon cores indicate remelting of parts of the Lignitz Plutonic Suite. The Untertal Plutonic Suite is poorly fractionated having comparatively low SiO2 and high Al2O3 contents. The rocks are strongly peraluminous, mostly magnesian and have calc-alkalic to alkali-calcic affinities. Emplacement of the Untertal Plutonic Suite can be related to a Devonian/early Carboniferous continental arc setting that formed during the early phases of the Variscan orogeny. The Eisenhut Plutonic Suite contains highly fractionated meta-granitoids with ages between 261.0±3.5 Ma and 271.2±5.7 Ma and ƐHf(t) values of 2.7 to 5.2. Its more juvenile ƐHf(t) values probably indicate renewed input of mantle-derived melts. This suite is peraluminous, ferroan and has a calc-alkalic to alkali-calcic character. It likely intruded during Permian lithospheric extension, following late Variscan orogeny that was accompanied by formation of horst-graben structures that finally resulted in the disintegration of Pangea.

Depositional environment and source rock characteristics in the Eastern Paratethys – Interpretation of organic matter in the Kura Basin (Azerbaijan)

Thu, 20 Aug 2026 00:00:00 GMT

The Paratethys and its predecessor, the Eocene Peri-Tethys, underwent several phases of oxygen-depletion, which led to the deposition of organic-rich sediments. These sediments serve as hydrocarbon source rocks in the Paratethys region, but also provide a record of the Paratethys´ evolution during the Cenozoic. The Cenozoic succession in Azerbaijan, located in the Eastern Paratethys, comprises three organic-rich units: (i) the Eocene Middle Koun Member, (ii) the Oligo-Miocene Maikop Group, and (iii) Upper Miocene paper shales in the Diatom Formation. This paper investigates the depositional environment of these units, the origin of their organic matter, the type of oil generated, and the thermal stability of the organic matter using maceral and biomarker analysis, pyrolysis-gas chromatography, and kinetic studies. The Middle Koun Member was deposited during the Middle Eocene Kuma anoxia, which affected large parts of the Caucasus region. It contains very high amounts of organic matter. Locally, the total organic carbon [TOC] content exceeds 10 % by weight. The organic matter is derived mainly from marine diatoms, Tasmanites algae and dinoflagellates. Evidence of methanogenic/ methanotrophic archaea and sulphate-reducing bacteria proves strictly anoxic conditions. Although the Middle Koun Member was deposited at greater water depths than formations of the same age in the western and northern Caucasus region, the characteristics of the organic matter are similar. The Upper Maikop Formation in Azerbaijan generally contains moderate amounts of TOC (~2–3 %) and a high proportion of terrigenous organic matter that has been deposited in a marine basin with reduced oxygen availability (Maikop anoxia). Within this succession, there are several distinct layers with higher TOC contents (≤5.12 %), which contain either marine or lacustrine algal material. A layer with organic matter of lacustrine origin in the upper part of the formation reflects the onset of the late Early Miocene (“Kozakhurian”) low-salinity event and provides the first evidence of an oil-prone source rock associated with this event outside the Black Sea. The paper shale interval in the Diatom Formation has been deposited at the shallow western margin of the South Caspian Basin during a late Miocene lowstand that caused fragmentation of the Paratethys and reduced salinity. Changes in biomarker composition reflect the decline in salinity. The very high amount of organic matter in the paper shales (locally >15 % TOC) originates mainly from algae (including the freshwater algae Pediastrum), diatoms, dinoflagellates, and microbial mats. Water column stratification during the early stages of paper shale accumulation contributed to oxygen depletion. The organic matter at the study sites onshore Azerbaijan is thermally immature. At oil window maturity, the Middle Koun Member and the paper shales will generate a paraffinic-naphthenic-aromatic oil. However, the wax content of paper shale oil will be slightly higher. The Maikop sediments will generate different oil types. A high wax paraffinic oil is predicted for the lacustrine sample. The organic matter in the paper shale is thermally more stable than that in the Middle Koun Member. Except for the lacustrine sample, hydrocarbon generation will occur over a wide temperature interval (40–60 °C).

Raman spectroscopy of carbonaceous material thermometry in the uppermost Austroalpine units, Eastern Alps – paleogeographic and tectonic implications

Wed, 15 Jul 2026 00:00:00 GMT

Raman spectroscopy of carbonaceous material (RSCM) estimates peak metamorphic temperatures in structural top units of the Eastern Alps (Steinach nappes, Gurktal nappes, Graz Paleozoic, Carboniferous of Nötsch, Kreuzeck-Goldeck-Gailtal Nappe, Diabase Zone of the North-Karawanken Range) and in their tectonic units below (Schneeberg Complex and Ötztal Nappe below the Steinach nappes, Heiligengeistklamm Nappe below the Gurktal nappes, Waxenegg Nappe below the Graz Paleozoic). The data are based on a standardized temperature calibration and describe the thermal structure of displaced tectonic units which were adjacent segments of the western Tethyan shelf during Permomesozoic times. In a west- to east profile through the Eastern Alps, RSCM data from the Koralpe-Wölz and Ötztal-Bundschuh nappe systems (Brenner area, Gurktal and Nock area, Remschnigg area, Grazer Bergland, Drau Range, North-Karawanken Range) show consistent peak metamorphic temperatures of 570-410 °C. Great similarities are found between the Steinach and Gurktal nappes. A thermal imprint of their post-Variscan (Pennsylvanian) molasse sediments is lower than 300 °C. Similar RSCM temperatures are found in Pennsylvanian sediments of the Graz Paleozoic and in the Saualpe, Remschnigg and Sausal sections of the Gurktal nappes, suggesting a similar burial depth during later times. The thermal structure of the Graz Paleozoic is characterized by an upright temperature trend within the nappe stack, by a thermal anomaly in the southeastern segment, and detachments disturbing the metamorphic pattern at the eastern margin. Permomesozoic burial heating of the Drau Range is constrained by upward decreasing RSCM temperatures. Temperatures <160 °C are estimated in the Carnian Raibl Formation. This pattern is overprinted in the central segment of the Gailtal Alps by a thermal anomaly with temperatures >200 °C in the Carnian stratigraphic level. It is suggested that the temperature gap at the base of the Drauzug-Gurktal Nappe System is related to low-angle detachments formed during post-orogenic collapse. Here, also RSCM temperatures increase locally.

Decoding lithological variability: alternating calcareous marls and their role in geomechanical rock mass properties

Thu, 02 Jul 2026 00:00:00 GMT

Finely interbedded rock formations are common within the argillaceous soft rock spectrum, yet they are often treated as homogeneous materials in rock engineering and underground construction. This assumption can lead to widely scattered and inaccurate geomechanical parameters, such as strength or stiffness. This study investigates the statistical distribution of marlstone sublayers in the argillaceous Unterangerberg Formation (Tyrol, Austria) and its correlation with geotechnical properties derived from laboratory tests. We analyze uniaxial compressive strength, splitting tensile strength, elasticity modulus, as well as cohesion and friction angle. The testing program encompasses multistage uniaxial and triaxial compression tests, as well as splitting tensile tests. A comprehensive dataset from core logging and rock mechanical laboratory testing is analyzed to assess whether variations in sublayer thickness contribute to the observed dispersion in these geomechanical properties. We also examine how alternative statistical summaries influence the perceived variability of parameters. The results show that the finely interbedded calcareous marlstone layers within the lithology exhibit distinctive geotechnical characteristics, with clay-rich layers generally showing tendencies towards lower strength. Variability in sublayer thickness influences the spread of laboratory test results, and layered specimens tend to yield smeared responses that reflect both constituents. These findings suggest that lithological heterogeneity plays an essential role in soft rock behavior. These results show the need to account for small-scale sedimentary layering and its statistical distribution when predicting the geomechanical behavior of argillaceous soft rock and interpreting laboratory test results for rock engineering applications. Incorporating probabilistic characterization of sublayer heterogeneity can improve predictive reliability and inform design decisions.

Thrust imbrication and subsequent normal faulting in the western Austroalpine: The Arlui Fault and the Jaggl Mesozoic sediments (Ötztal Nappe, Vinschgau, Italy)

Thu, 21 May 2026 00:00:00 GMT

Jaggl is a mountain in the Upper Vinschgau, built up of Mesozoic sedimentary rocks and surrounded by crystalline basement rocks of the Ötztal Nappe. The Jaggl sedimentary rocks were originally interpreted as a remnant of the sedimentary cover of the Ötztal basement (“cover hypothesis”). Later, a different interpretation became prevalent, according to which the sedimentary rocks and a portion of the adjoining basement rocks represent a tectonic window into a deeper unit underlying the Ötztal Nappe (“window hypothesis”). A key role is played by the steeply southeast-dipping Arlui Fault along which the Jaggl Mesozoic rocks to the Southeast are in contact with Ötztal basement rocks to the Northwest. In the “window hypothesis”, the displacement along the Arlui Fault should be southeast-side-up, whereas in the “cover hypothesis”, it should be southeast-side-down. Our study of ductile (greenschist facies) to brittle fault rocks along the Arlui Fault yielded exclusively evidence for southeast-side-down, i.e. normal faulting. In addition, we identified the prolongation of the Arlui Fault towards northeast, represented by a top-southeast, greenschist-facies mylonite zone within the amphibolite-facies Ötztal basement. The Arlui Normal Fault belongs to the system of normal faults that overprinted the Austroalpine nappe stack during the Late Cretaceous, the Jaggl rocks are a downthrown part of the cover of the Ötztal Nappe, and the Jaggl Window does not exist.

Old orogen – young topography: Linking rift evolution, thermal overprinting, and apatite (U-Th)/He thermochronology in the Black Forest and Vosges Mountains

Tue, 17 Mar 2026 00:00:00 GMT

Investigating the thermal evolution of continental rifts is essential for understanding how lithospheric extension, surface uplift, and exhumation are recorded in the shallow crust. However, interpreting low-temperature thermochronological data in rift settings remains challenging, particularly where exhumation magnitudes are small and geothermal gradients are elevated and spatially heterogeneous. In such environments, cooling ages may reflect a combination of regional tectonic processes and localized thermal overprints, complicating the reconstruction of rift-related exhumation histories. Here, we present new apatite (U-Th)/He ages from the Black Forest and Vosges Mountains, integrated with published apatite fission-track data, to reconstruct the Cenozoic thermal evolution of the Upper Rhine Graben rift flanks. Sampling along multiple transects perpendicular to the rift axis provides the spatial resolution required to distinguish regional cooling trends from localized thermal perturbations. The data and time-temperature modeling indicate that maximum temperatures were reached during the Late Cretaceous to Paleocene, approaching but generally not exceeding the apatite partial retention and annealing zones (PRZ/PAZ). Cooling occurred in three main phases during the Late Cretaceous, Eocene, and Oligocene, resulting in pronounced single-grain apatite (U-Th)/He age dispersion. A regionally pervasive Miocene reheating event is not required to explain the observed age patterns. Instead, the data are best explained by a combination of incomplete resetting, radiation damage effects, and localized hydrothermal influences in the vicinity of normal faults. These results highlight the importance of integrating multiple low-temperature thermochronometers with high spatial sampling density to disentangle tectonically driven cooling from localized thermal overprinting in intracontinental rift systems.

Mine water composition in abandoned copper mines of the UNESCO Global Geopark Ore of the Alps

Tue, 17 Mar 2026 00:00:00 GMT

The central theme of the UNESCO Global Geopark “Ore of the Alps” in Salzburg’s Pongau region is prehistoric and historic copper mining in the Eastern Alpine Greywacke Zone. Much is known about the history and geology of the ore deposits. However, to date the effects of mining on groundwater quality is not investigated yet. From January to July 2024, monthly samples were taken from mine water outlets and analysed for field parameters, main and trace elements as well as sulphate isotopes. The quality of mine water was compared with reference stations sampled at the same time. The measurements show that the pH values of the mine water are in the slightly alkaline range, meaning that the heavy metal concentration is mostly harmless, although the mine water has significantly higher concentration than the reference water. The sulphate levels in the mine waters are significantly higher than those of the reference waters. Isotope analyses indicate that the increased sulphate levels are due to sulphide oxidation and thus to mining. Although systematic discharge measurements were not possible observations in one of the mines indicate a positive correlation between discharge and mineralisation. The study shows that historical mining continues to affect water composition. However, as the main ore is chalcopyrite and the mineralisation of the ore veins is bound to carbonates, the effects of sulphide weathering in the aquifer are buffered. The mine water remains pH-neutral to slightly alkaline, so it has only a low potential to dissolve harmful heavy metals. The study provides an overview of the current groundwater situation in the ‘Ore of the Alps’ UNESCO Global Geopark and confirms that there is no groundwater contamination risk from historic mining facilities. It thus contributes to a holistic understanding of this specific geo-heritage.

Lu-Hf garnet dating of eclogite from Hochgrößen (Speik Complex, Lower Central Austroalpine): Evidence for Silurian (c. 438 Ma) high-pressure metamorphism

Sun, 12 Oct 2025 00:00:00 GMT

In the eastern European Alps, lenses of eclogite occur within a serpentinite body at Hochgrosen in northern Styria, Austria. These rocks belong to the Speik Complex, a subducted meta-ophiolite in the Lower Central Austroalpine basement, and show geochemical characteristics (relative abundances of Ti, V, Sr, Sc, and Si) of MORB magmatites with a backarc basin affinity. Three samples of partly retrogressed eclogites were studied using Lu-Hf geochronology on whole rock and garnet separates. One sample yields a well-defined four-point Lu-Hf isochron at 437.9 ± 0.8 Ma (Early Silurian). Although partly retrogressed to amphibolite facies, prior equilibration in the eclogite facies is confirmed by the occurrence of omphacite (33.2% jadeite component) inclusions in garnet. Garnet shows a bell-shaped Lu concentration profile, indicating that the Lu-Hf age is related to garnet growth, i.e. eclogite-facies metamorphism. The two other samples were more strongly retrogressed and did not yield isochrons, probably because of Variscan metamorphic overprint. With this new age, the Hochgrosen eclogite is now the oldest eclogite dated so far in the Austroalpine nappes and reflects subduction at the northern margin of Gondwana during the Early Silurian.

Understanding the Geomorphology of Deep-Seated Landslides: Insights from the Váh River Valley, Western Carpathians, Slovakia

Wed, 08 Oct 2025 00:00:00 GMT

This study examines the geomorphology of deep-seated landslides (DSLs) in the Western Carpathians, Slovakia, focusing on five key DSL areas along the Váh River Valley within the northern Veľká Fatra Mountains. Through an integrated approach combining fieldwork, GIS analysis, and Red Relief Image Map (RRIM) visualization, the research identifies and analyzes geomorphic features such as deep-seated landslide blocks, earthflows, and gravitational scarps. GIS methods reveal the spatial distribution and morphological characteristics of these mass movements, while RRIM emphasizes key gravitational features such as scarps, trenches, and cliffs. The study further differentiates between types of mass movement, ranging from slow, continuous deformation to catastrophic slope failures. Results emphasize the crucial role of geological and tectonic conditions in influencing landslide initiation, propagation, and evolution. The findings explain the complex interplay between geological structures and geomorphic processes that shape the Western Carpathian landscape. This work contributes to advancing the understanding of DSL dynamics and offers essential insights for regional land-use planning and hazard mitigation. It provides a foundation for applying similar methodologies to comparable geomorphic phenomena globally, addressing both scientific and practical challenges in landslide-prone regions.

From Mass Movements to Mitigation Measures: A Statistical Evaluation of Landslides in the Austrian Federal Railway Network

Wed, 08 Oct 2025 00:00:00 GMT

Mass movements, especially landslides, pose a severe safety risk for critical infrastructure, such as railroads, and will very likely increase in the near future due to global warming. As part of the development of a network-wide natural hazard management strategy for the Austrian Federal Railways (ÖBB Infrastruktur AG), the landslide events of the last 20 years were recorded in an event register. The article provides a descriptive statistical evaluation of this landslide inventory, with the aim of deriving general conclusions for landslide hazard mitigation. About 91.9 % of all events were classified as shallow landslides (depth of the slip surface <2 m), which were mostly anthropogenically induced, and 49.0% of all events were attributed to the design and maintenance of roads and railways, thus being particularly related to fill slopes, cut slopes and drainage systems. Due to the frequent lack of geomorphological indicators, the ‘classic’ approach in landslide mitigation (i.e., geomorphological mapping, geological exploration, geotechnical monitoring and remediation) is only suitable to a very limited extent for small events. Quantitative landslide susceptibility assessment is therefore becoming increasingly important, even though the results are often questionable in heavily anthropogenically altered terrain, such as cut and fill slopes along traffic routes. In these areas, depending on the specific cause, additional measures (closer construction supervision, reinforced maintenance, risk communication, legal approaches) are required. As a consequence of the susceptibility analysis and the resulting designation of numerous landslide-prone areas, the need for the construction and planning of linear protective structures and monitoring systems is becoming increasingly apparent.

Re-interpretation of the TRANSALP seismic section in the light of new tectonic subdivisions of the western Northern Calcareous Alps

Thu, 21 Aug 2025 00:00:00 GMT

In this study we present a reprocessed part of the TRANSALP seismic section between the Austrian-German border and the Ziller valley. It offers new insights into deep tectonic structures around the lower Inn valley, which are interpreted with the use of recently published tectonic classifications of the area. The lateral extension of the observed major structures is discussed with another deep cross section across the Kaisergebirge. This study demonstrates that Paleogene out-of-sequence thrusting locally controls the relationship between different tectonic units. Paleogene thrusts overprint pre-existing nappe boundaries, and were erroneously interpreted as Cretaceous nappe boundary. This is the case for the large, laterally persistent unit of the Tirolic Staufen-Höllengebirge- and Bajuvaric Lechtal nappes, which are separated by a Paleogene out-of-sequence thrust and the Oligo-Miocene Inntal Shear Zone. Consequently, this means to eliminate the concept of a tectonic subdivision solely based on in-sequence nappe stacking, and Triassic sedimentary facies distribution. We suggest to use a nomenclature also based on geometry of the Permo-Mesozoic cover nappes. Our proposed nappe classification leads to a newly defined Karwendel-Höllengebirge Nappe, occupying most of the middle to western Northern Calcareous Alps, incorporating the crystalline basement, which is in primary contact with the Permo-Mesozoic cover. The partly existing sedimentary contact to the basement further allows us to propose a new terminology on cover nappe systems in the Northern Calcareous Alps, getting rid of the terms Bajuvaric, Tirolic and Juvavic. Oligocene-Miocene thrusting and eastward extrusion along the Subtauern Ramp and steep strike-slip structures - like the Inntal shear zone – have further complicated the structure of the region, off-setting older in- and out-of-sequence structures, and finally exhuming basement units underneath the cover nappe stack south of the Inn valley.

Sedimentological and pore-scale characterisation of the Bockfließ Formation, Central Vienna Basin: implications for sealing potential

Thu, 21 Aug 2025 00:00:00 GMT

The Bockflies Formation represents parts of the Ottnangian Stage of the Lower Miocene in the Central Vienna Basin and is characterized by the type section from the Matzen 269 well. However, a detailed sedimentological characterisation of the type section has not been published. Previous studies on the Bockflies Formation predominantly focused on fossil assemblages, which indicated a lagoonal depositional environment with riverine input. This study intends to complement previous paleontological studies with a detailed sedimentological analysis, involving lithological, petrographical, ichnological, and macrofossil content descriptions of the cored sections from the Matzen 269 well. The sedimentological data was thereafter used to establish lithofacies and determine depositional environments represented by the cores. This suggests that the Bockflies Formation in the study area largely represents a coastal lagoon depositional setting, with identified depositional environments include lagoon, washover fan, channel fills (inlet) and shoreface. The lagoon facies is the most dominant and relevant sealing facies in the Bockflies Formation and could span tens of kilometres at its widest point and most likely formed due to coastal sea flooding. However, a connection was maintained between the lagoon and the sea, representing an inundation model, with modern analogues found in the Venice Lagoon in Mediterranean Sea and the Curonian Lagoon in the Baltic Sea.The selected core sections were also evaluated for their sealing potential as the formation is a regional caprock for the underlying fractured carbonate reservoirs. The sealing potential of a caprock system depends primarily on its geometry, storage capacity, and structural integrity. To evaluate the sealing potential, lagoon facies were further subjected to XRD, QEMSCAN, MICP and coreDNA analyses. Based on these, the lagoon facies would most likely act as an intraformational seal, given the presence of other non-sealing facies. Rock strength data obtained through scratch testing indicate a subtle variation in strength within the lagoon facies, attributed to clay content. Moreover, the compositional make-up of the lagoon facies is akin to ‘sealing shales’ reported elsewhere. Additionally, XRD analysis revealed that illite is the dominant clay mineral across the lagoon facies, which is a non-reactive clay mineral.

Deep-marine elasmobranchs from the Badenian (Langhian, Middle Miocene) of the Central Paratethys of Austria

Wed, 13 Aug 2025 00:00:00 GMT

This study reports on a rare assemblage of deep-marine elasmobranchs from the middle Badenian (Langhian) of Austria, which has been recovered by extensive bulk sampling of sediment deposited in the Krems embayment. The applied multidisciplinary approach enabled an age assignment, placing the assemblage around the mid Badenian flooding event (14.59 ± 0.2 Ma). Palaeoenvironmental reconstruction, based on a well-preserved foraminifera assemblage and fish otoliths, indicates predominantly oxic to suboxic with partially dysoxic conditions of a rather deep-marine (>100 m) setting, which align with the recovered elasmobranch taxa. Despite analyzing 180 kilograms of sediment, only five elasmobranch teeth were recovered. The low number of teeth and the extraordinarily well-preserved foraminifera argue for an autochthonous deposition and point to high sedimentation rates associated with the flooding event. The teeth represent five different elasmobranch orders (Squaliformes, Squatiniformes, Carcharhiniformes, Torpediniformes, and Myliobatiformes) with a wide range of feeding behaviors, providing new insights into the ecological structure of this deep-marine environment. Despite common genera known from other marine settings of the Paratethyan realm (e.g., Squatina, Scyliorhinus, and Centrophorus), this study documents the first distinct records of Torpedo and Mobula from Austria, expanding the known palaeogeographic distribution of these taxa.

Seismic velocity structure and seismotectonics of the southern Vienna Basin (Austria) with a large-N nodal deployment

Thu, 07 Aug 2025 00:00:00 GMT

In spring 2024, we deployed a large seismic nodal array across the southern Vienna Basin, Austria. Using a machine-learning approach, we constructed a seismic catalog for the 60-day deployment period and reliably identified 100 events. We applied a local earthquake tomography inversion procedure to relocate the detected events and derive three-dimensional P- and S-wave velocity models and VP/VS estimates. The results reveal a low-velocity anomaly with high VP/VS estimates, corresponding to the Neogene basin structure. In contrast, high-velocity anomalies with low VP/VS estimates highlight nappe systems associated with the Alpine Orogen. Most of the relocated seismicity during the deployment is linked to the April 14th, 2024, M ~ 3 earthquake. The mechanism for this event, along with its aftershock distribution, suggest that the rupture occurred on a normal splay fault of the Vienna Basin Transfer Fault System, situated near its intersection with the basal detachment at depth. As this area is highlighted for its geothermal resource potential, a comprehensive understanding of geological structures and potential hazards is essential for responsible resource development.

Revisiting the (pre-Variscan) Galatia/Ligeria – Armorica terrane conception from an Austrian perspective

Thu, 07 Aug 2025 00:00:00 GMT

According to the original Galatia/Ligeria-Armorica terrane model, almost all pre-Variscan units in Austria (i.e., in the Alps as well as in the Bohemian Massif) were part of the Galatian/Ligerian microplate. We raise arguments against this interpretation based on a lithological and geochronological comparison of key regions (southern Bohemian Massif, Alps, Massif Central). We propose that the (non-Avalonian) parts of the southern Bohemian Massif actually belong to the Armorican microplate. A Trans-Mid-European belt of Upper Devonian ophiolite remnants and coeval primitive arc granitoids strikes from the northern Massif Central over the southern Vosges and the southern Black Forest onto the basement under the northern front of the Alps. It is interpreted as remnant oceanic and island-arc-type crust that marks the boundary between the Armorican and the Galatian/Ligerian terrane. Like most previous authors, we consider Armorica to be a Cadomian/Early Palaeozoic peri-Gondwana terrane that originated in the fore field of the Sahara metacraton and the West African craton. However, Galatia/Ligeria can be interpreted as Cadomian/Early Palaeozoic peri-Gondwana crust that formed farther east in front of the Arabian-Nubian Shield. After their Devonian off-drift from Gondwana, the two terranes approached each other and finally collided during the Variscan orogeny.

Kinematics of the Plattengneis Shear Zone, Koralpe, Eastern Alps. Constraints from Quartz Lattice Preferred Orientations

Wed, 25 Jun 2025 00:00:00 GMT

Large-scale models for the tectonometamorphic evolution of the Koralpe (Eastern Alps) must account for the kinematics of deformation in the regional, intracrustal transport horizon known as the Plattengneis shear zone. Published tectonic models have invoked a range of interpretations that imply different distributions for strain geometry and shear sense, both laterally from north to south and vertically across the flat-lying shear zone. To acquire data suitable for differentiating among such models, this study presents quartz lattice preferred orientations, measured using electron backscatter diffraction, from oriented samples collected specifically to provide systematic vertical and lateral coverage of the Plattengneis shear zone. The vertical position within the shear zone is determined using a 3D model of the shear zone geometry that was made for this study in refinement of earlier work. The results yield information on activated slip systems, deformation temperatures and shear sense as a function of the vertical and lateral position within the shear zone. No systematic correlations were found between the vertical position of samples within the shear zone and their inferred sense of shear, or strain geometry. Deformation temperatures, however, display lateral distributions consistent with the regional metamorphic temperature field-gradient defined by prior petrological studies, implying that deformation of the shear zone took place predominantly at or near peak metamorphic temperatures. The observations, measurements and inferences from this study indicate that deformation of the Plattengneis occurred within the range of ~500 °C to 700 °C in an environment that has largely, but not exclusively, non-coaxial top-to-the-north shear sense. This result is consistent with recently invoked tectonic models for the shear zone.

A new nothosaurid taxon from the Middle Triassic of Carinthia, Austria

Wed, 25 Jun 2025 00:00:00 GMT

Two recently excavated specimens of a medium-sized (up to 115 cm long) new nothosaurid taxon are described from a Middle Triassic locality in the Gailtal Alps (Austroalpine Drau Range) of Carinthia. The holotype is a complete and articulated specimen exposed in dorsal view. The referred specimen, also prepared in dorsal view, lacks the skull and is slightly smaller in overall body size. The new taxon shows an exclusive combination of morphological characters. It shares with nothosaurs the large upper temporal openings and anterolaterally expanded corners of the clavicle. Lariosaur affinities are the large number of carpalia and the configuration of the sacral region. Similarities with ceresiosaurs are the increased height of neural spines in the posterior neck and anterior trunk region, pending additionally the distinctiveness of ceresiosaurs and lariosaurs. Further on, its skull morphology, as far as sutures are discernible, shows a rectangular prefrontal that extends from the anteromedial orbital margin to the posterolateral margin of the external naris, which is a rather rare shape in nothosaurids. The morphology of the humerus and ulna as well as limb ratios are considered as autapomorphies, and a new taxon, Carinthiasaurus kandutschi gen. et sp. nov. is erected. Its phylogenetic relationships are however not tested due to the unclear status of Ceresiosaurus and the general ambiguous phylogenetic relationships within Nothosauridae, both awaiting a thorough revision.

New single-crystal X-ray diffraction and Raman spectroscopic data of natural bismoclite BiOCl

Thu, 19 Jun 2025 00:00:00 GMT

The structure of bismoclite BiOCl from the Jean Baptiste mine, Lavrion area, Greece, was characterised by single-crystal X-ray diffraction. The mineral is tetragonal, space group P4/nmm with unit-cell parameters a = 3.887 (2), c = 7.357 (5) Å, Z = 2, V = 111.16 (14) Å3 (R1 = 0.0134 and wR2 = 0.0363). Bismoclite is isostructural with the mineral matlockite PbFCl. Chemical analyses showed in some cases partial substitution of Bi by Ca and traces of Fe incorporated. A Raman spectrum of bismoclite reveals the most intense Raman band at 144 cm–1 and additional bands of lower intensity at 198 and 396 cm–1.

Austrian Journal of Earth Sciences Feed

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A new nothosaurid taxon from the Middle Triassic of Carinthia, Austria

New single-crystal X-ray diffraction and Raman spectroscopic data of natural bismoclite BiOCl

New insights into the Cambrian to Permian evolution of the Austroalpine basement units of the Schladming Crystalline by UPb zircon geochronology and granitoid geochemistry