rss_2.0Austrian Journal of Earth Sciences FeedSciendo RSS Feed for Austrian Journal of Earth Sciences Journal of Earth Sciences 's Cover search of the oldest rock of Austria: The Hauergraben Gneiss, a 1.40 Ga old mafic quartz-monzonitic inlayer in the Dobra Gneiss (Drosendorf Unit, Bohemian Massif) as a new candidate<abstract><title style='display:none'>Abstract</title><p>For a long time, the 1.38 Ga old Dobra Gneiss (Type A) from the Lower Austrian Drosendorf Unit (Moldanubian Zone, Bohemian Massif) was considered the oldest rock of Austria. We now have dated zircons from a local mafic inlayer in the Dobra Gneiss Type A, termed Hauergraben Gneiss. This small-scale amphibole-bearing orthogneiss has a magmatic formation age of 1.40 Ga, and is, thus, to the present state of knowledge, the oldest rock of Austria. Based on geochemical investigations, the protolith of the Hauergraben Gneiss was a quartz-monzonite. It probably originated in a volcanic arc setting like the Dobra Gneiss, but shows distinctively higher transitional metal contents (especially Cr and Co), higher Ba and Sr, and higher light rare earth element contents, which hint at a lithospheric mantle input. This 1.40 Ga old mafic arc material was then incorporated into the 1.38 Ga old intrusive protolith of the Dobra Gneiss, probably in the form of enclaves. Considering the model that the Drosendorf Unit was part of Amazonia until the late Neoproterozoic, we propose that both, Dobra Gneiss Type A and Hauergraben Gneiss, originated at the western margin of the Columbia super-continent, where several long-lived Mesoproterozoic volcanic arcs existed and accreted over time. During the Variscan orogeny, the Hauergraben Gneiss experienced peak metamorphic temperatures of ~620 °C at pressures of ~6 kbar, as can be deduced from amphibole thermobarometry. This is in line with published peak-<italic>PT</italic> estimates from other parts of the Drosendorf Unit. Formation of secondary low-Al magnesiohornblende at the expense of the earlier edenitic/pargasitic peak amphibole indicates a subsequent retrograde overprint.</p></abstract>ARTICLE2021-04-22T00:00:00.000+00:00The Haidbach deposit in the Central Tauern Window, Eastern Alps, Austria: a metamorphosed orthomagmatic Ni-Cu-Co-PGE mineralization in the Polymetallic Ore District Venediger Nappe System – Hollersbach Complex<abstract><title style='display:none'>Abstract</title><p>Cu-Ni-Co-PGE mineralization occurs at Haidbachgraben in the Early Palaeozoic, Subpenninic Hollersbach Complex of the Central Tauern Window, Austria. Massive sulfide ore formed from sulfide melt segregated from silicate melt during intrusion of pyroxenite into magmatic rocks formed in an MORB-type environment. Relics of magmatic minerals include chromian spinel and polyphase sulfide droplets composed of pyrrhotite, chalcopyrite and pentlandite preserved in recrystallized pyrite. Both ore and host rocks were multiply deformed and metamorphosed, leading to hornblendite carrying the ore, enveloped by chlorite-epidote schist. Conditions of – likely Variscan – amphibolite facies metamorphism are documented by relict pargasitic cores in hornblende and actinolite-tremolite, and by ternary sulfarsenide compositions in the Co-Ni-Fe solid solution series that are the most common accessory minerals found in the sulfide ore. Pyrrhotite, pentlandite, chalcopyrite and pyrite are the major sulfide minerals. Chalcopyrite is Cd-rich and retains a high-temperature magmatic signature. High Co/Sb and moderate Se/As ratios in pyrite also point to a magmatic environment of mineralization. The accessory mineral assemblage of small grain size (mostly &lt;10 µm) comprises native Au-Ag alloy and petzite as Au-Ag minerals, sperrylite, a variety of Pd tellurides and bismuthotellurides with elevated Sb, irarsite, and Re sulfides such as tarkianite and a Pb-Re sulfide. In addition, minor molybdenite, bournonite, scheelite and selenides have been identified. Two precious metal assemblages are present in individual samples: (1) hessite associated with Pd tellurides, often accompanied by sphalerite and chalcopyrite; (2) tarkianite forming euhedral inclusions in pyrite. Sperrylite and Au-Ag native alloys are present throughout and were also detected in silicate matrix. Most of the precious metal-bearing phases must have formed during recrystallization of base metal sulfides after the magmatic, and probably during later metamorphic events terminating in the Neoalpine Tauern crystallization.</p></abstract>ARTICLE2021-01-29T00:00:00.000+00:00Palynology of the Cenomanian Raha Formation, Gulf of Suez, Egypt: Biostratigraphical, palaeoenvironmental and palaeobiogeographical implications<abstract><title style='display:none'>Abstract</title><p>The current study presents a fully qualitative palynological investigation carried out on the Raha Formation encountered from three wells in the Bakr Oil Field of the Gulf of Suez, Egypt. Around 30 species of pteridophytic spores, 26 species of angiosperm pollen, 24 species of gymnosperm pollen and 27 species of dinoflagellate cysts have been recorded. However, achritarchs, microforaminiferal test linings and freshwater algae are impoverished and sparsely documented throughout the Raha Formation. Two palynozones have been identified based on some stratigraphically significant pollen and spores, arranged from youngest to oldest: (1) Palynozone I (Classopollis brasiliensis–Tricolpites sagax Assemblage Zone) of late Cenomanian age; (2) Palynozone II (Afropollis jardinus–Crybelosporites pannuceus Assemblage Zone) of early-middle Cenomanian age. The distribution and ecological affiliation of specific palynomorph species, as well as various palynofacies parameters, are interpreted. A shallow marine environment from supratidal to distal inner neritic under proximal suboxic–anoxic to dysoxic–anoxic shelf conditions is reconstructed. Palaeobiogeographically, the absence of elaters from the recovered taxa is interpreted in terms of minor floral variation. This may be attributed to climatic and/or an environment-controlled niche establishment, which possibly was shaped by the existence of a physical barrier hindering the distribution of such type of elaterate parent plants.</p></abstract>ARTICLE2018-09-06T00:00:00.000+00:00Late Glacial and Holocene sedimentary infill of Lake Mondsee (Eastern Alps, Austria) and historical rockfall activity revealed by reflection seismics and sediment core analysis<abstract><title style='display:none'>Abstract</title><p> Glacigenic perialpine lakes can constitute continuous post-last glacial maximum (LGM) geological archives which allow reconstruction of both lake-specific sedimentological processes and the paleoenvironmental setting of lakes. Lake Mondsee is one among several perialpine lakes in the Salzkammergut, Upper Austria, and has been previously studied in terms of paleoclimate, paleolimnology and (paleo)ecology. However, the full extent and environment of Late Glacial to Holocene sediment deposition had remained unknown, and it was not clear whether previously studied core sections were fully representative of 3D sediment accumulation patterns. In this study, the sedimentary infill of Lake Mondsee was examined via high-resolution seismic reflection survey over a 57-km extent (3.5 kHz pinger source) and a sediment core extracted from the deepest part of the lake, with a continuous length of 13.76 m. In the northern basin, seismic penetration is strongly limited in most areas because of abundant shallow gas (causing acoustic blanking). In the deeper areas, the acoustic signal reaches depths of up to 80 ms TWT (two-way travel time), representing a postglacial sedimentary sequence of at least 60-m thickness. Holocene deposits constitute only the uppermost 11.5 m of the sedimentary succession. Postglacial seismic stratigraphy of Lake Mondsee closely resembles those of well-studied French and Swiss perialpine lakes, with our data showing that most of Lake Mondsee’s sedimentary basin infill was deposited within a short time period (between 19,000 BP and 14,500 BP) after the Traun Glacier retreated from the Mondsee area, indicating an average sedimentation rate of about 1.4 cm/yr. Compared to other perialpine lakes, the seismic data from Lake Mondsee reveal little indication of mass movement activities during the Holocene. One exception, however, is rockfalls that originate from a steep cliff, the Kienbergwand, situated on the southern shore of Lake Mondsee, where, in the adjacent part of the lake, seismic profiles show mass transport deposits (MTDs), which extend approximately 450 m from the shore and are mappable over an area of about 45,300 m<sup>2</sup>. Sediment cores targeting the MTDs show two separate rockfall events. The older event consists of clast-supported angular dolomitic gravels and sands, showing high amounts of fine fraction. The younger event exhibits dolomitic clasts of up to 1.5 cm in diameter, which is mixed within a lacustrine muddy matrix. Radiocarbon dating and correlations with varve-dated sediment cores hint at respective ages of AD 1484 ± 7 for Event 1 and AD 1639 ± 5 for Event 2. As our data show no evidence of larger-scale mass movements affecting Lake Mondsee and its surroundings, we infer that the current-day morphology of the Kienbergwand is the result of infrequent medium-scale rockfalls.</p></abstract>ARTICLE2018-09-06T00:00:00.000+00:00Stable isotope geochemistry and petrography of the Qorveh–Takab travertines in northwest Iran<abstract><title style='display:none'>Abstract</title><p> The Qorveh-Takab travertines, which are connected to thermal springs, are situated in the northwest of the Sanandaj- Sirjan metamorphic zone in Iran. In this study, the travertines were investigated applying petrography, mineralogy and isotope geochemistry. Oxygen and carbon isotope geochemistry, petrography, scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) analysis were used to determine the source of the CO<sub>2</sub> and the lithofacies and to classify the travertines. Isotope studies, morphological and mineralogical observations and distribution of travertines revealed that the travertines of the Qorveh-Takab could be of thermal water origin and, therefore, belong to the thermogene travertine category. These travertines are usually massive with mound-type morphology and are essentially found in regions with recent volcanic or high tectonic activity. The measured δ<sup>13</sup>C values of the travertines indicate that the δ<sup>13</sup>C of the CO<sub>2</sub> released from the water during travertine deposition, while the source of the CO<sub>2</sub> in the water springs seems to have been of crustal magmatic affinity. These travertines are divided into two lithofacies: (1) crystalline crust travertine and (2) pebbly (phytoclastic travertine with pebble- size extraclasts) travertine. δ<sup>18</sup>O and δ<sup>13</sup>C values of travertines are -0.6 to -11.9 (‰VPDB) and +6.08 to +9.84 (‰VPDB), respectively. A probable reason for the heavy carbon isotope content observed in these deposits is the presence of algae microorganisms, which was verified by SEM images. Fissure ridges, fluvial crusts with oncoids, and mound morphological features are observed in the study area. Based on the petrographic and SEM criteria, Qorveh-Takab travertines are classified into four groups: (1) compacted, (2) laminated, (3) iron-rich spring deposit and (4) aragonite-bearing travertines. Stable isotope compositions of Turkish travertines are largely similar to the travertines in the study area.</p></abstract>ARTICLE2018-09-06T00:00:00.000+00:00Sinemurian biostratigraphy of the Tannscharten section near Reichraming (Lower Jurassic, Schneeberg Syncline, Northern Calcareous Alps)<abstract><title style='display:none'>Abstract</title><p> Lower Jurassic ammonites were collected from deep-water limestones of the Tannscharten section, southwest of Reichraming (Northern Calcareous Alps, Upper Austria). The outcrop provides a rich Upper Sinemurian (Lower Jurassic) ammonite fauna of the Allgäu Formation. The area is situated in the westernmost part of the Schneeberg Syncline in the north of the Reichraming Nappe (High Bajuvaric Unit). The ammonite fauna consists of seven different genera, each apparently represented by 1-2 species. Echioceratids are the most frequent components (Echioceras, Leptechioceras, Paltechioceras), followed by the phylloceratids (Juraphyllites, Partschiceras) and oxynoticeratids (Gleviceras, Paroxynoticeras). Juraphyllites libertus, Partschiceras striatocostatum, Gleviceras paniceum, Echioceras quenstedti, Echioceras raricostatoides, Paltechioceras boehmi, Leptechioceras meigeni, Leptechioceras macdonnelli and Paltechioceras oosteri are new for the Schneeberg Syncline and allow for the first time a detailed biostratigraphy of the Echioceras raricostatum zone. The assemblage is correlated with other faunae from Austria, Germany, United Kingdom, France, Switzerland and Romania. The cephalopod fauna consists of a mix of elements from the Northwest European Province and the Mediterranean Province. The detailed biostratigraphy based on ammonites is presented here.</p></abstract>ARTICLE2018-09-06T00:00:00.000+00:00Crustal geomagnetic field and secular variation by regional and global models for Austria<abstract><title style='display:none'>Abstract</title><p> Using 12-year-long series of data (2001-2012) from geomagnetic observatories and repeat stations in Austria and its neighboring countries, a regional spatial-temporal (ST) model is developed based on the polynomial expansion consisting of latitude, longitude, and time of the geomagnetic field components and total magnetic field F. Additionally, we have used three different global models (CHAOS-5, POMME-9, and EMM2015), which are built on spherical harmonics up to a maximum degree L<sub>max</sub> and give the core field and crustal field separately. The normal field provided by the ST model and its “model bias”, which comprise the residuals of the differences between measured and predicted values, are calculated and the respective maps are shown. The residuals are considered an estimate of the local crustal field. In the case of global models, we have applied for each of these three methods to calculate the “model bias”: residuals of the differences between observed values and predicted values of the model, residuals of the differences between observed values and core field values of the model, and the average bias for the period 2001-2012. The normal field of the region of Austria provided by each global model is also calculated. Generally, the regional and global models yield relatively similar crustal fields for the Austrian region, especially when the first method is used. The normal fields calculated by them are in good agreement with each other. Each of the global models directly provides the crustal field, and they are compared with the aeromagnetic data provided by aeromagnetic surveys over the Austrian region. The ST model is in better agreement with aeromagnetic data. We have also analyzed the secular variation over the region, which is calculated from the rate of change of normal field given by the ST and global models.</p></abstract>ARTICLE2018-09-06T00:00:00.000+00:00Chemical denudation rates of a small torrential catchment in the Northern Calcareous Alps<abstract><title style='display:none'>Abstract</title><p> In this study, we present chemical denudation rates derived from measuring the dissolved load of an alpine catchment located in Salzburg, Austria. The catchment has a drainage area of about 7 km<sup>2</sup> and is predominantly covered by limestone- rich glacial deposits and carbonate rocks that are characteristic of the Northern Calcareous Alps. To obtain catchment-wide chemical denudation rates, we integrated discharge time series that were measured by a permanent water gauge of the Austrian Service for Torrent and Avalanche Control to compute the total discharge of the investigated catchment over a period of one year. During the same period, samples were taken during several campaigns to consider variations of the dissolved load. Samples were collected at high and low runoff conditions to study the effect of precipitation and at different locations along the tributaries to account for lithological variations of the river beds on the dissolved load. For the investigation period of one year, 2.97 ×10<sup>6</sup> m<sup>3</sup> of discharge was measured at the catchment outlet. The summed cation-concentration varies between about 85 mg/l for dry-conditions and 75 mg/l for rainy-conditions at the gauge and consists predominantly of Ca<sup>2+</sup>and Mg<sup>2+</sup> cations. Based on the total discharge of the river integrated over a period of one year, and the average dissolved load determined from water samples, we obtained a chemical denudation rate of 0.094 mm/a. The results imply that chemical denudation is a significant driver for redistributing mass in carbonate-dominated catchments and might be the dominant erosional process in such settings.</p></abstract>ARTICLE2018-09-06T00:00:00.000+00:00Mineralogy and facies variations of Devonian and Carboniferous shales in the Ukrainian Dniepr-Donets Basin<abstract><title style='display:none'>Abstract</title><p> The mineralogy of Devonian to Carboniferous shales from the Ukrainian Dniepr-Donets Basin (DDB) was investigated during this study. These shales show a high compositional variability in vertical and lateral directions. Furthermore, stratigraphic trends were found to be controlled both by climatic factors as well as by changing detrital input from the hinterland. High kaolinite contents and predominance of kaolinite over illite in the Tournaisian and partly in the lower Visean units are likely a result of intense chemical weathering related to the Hangenberg climatic event at the Devonian/ Tournaisian boundary. In contrast, abnormally high kaolinite contents in upper Visean and Serpukhovian samples at the basin center might be caused by different transport properties of kaolinite and illite, leading to selective concentration of small detrital kaolinite particles, which are often in the sub-micrometer range according to scanning electron microscopy observations. K/Al elemental ratios correlate well with illite/kaolinite ratios for samples in which significant amounts of both clay minerals are present, which enables a pre-evaluation of the relative kaolinite content based on bulk geochemical data. As kaolinite is suggested to decrease the fraccability of shales and to have a great influence on their wetting behaviour, this is useful information for explorational purposes. Higher feldspar contents in Devonian and Tournaisian samples, especially along the NE basin margin and in the shallow NW part of the DDB, are likely related to increased detrital input from magmatic precursors (e.g. in the Voronezh Massif ) during (and shortly after) the active rift stage of the DDB. In general, feldspar contents are higher in proximal positions compared to the basin center, which is likely a result of shorter transport distances of the comparably large feldspar grains. Finally, the presence of expandable clay minerals down to depths of 6 km and the fact that no thermal maturity trend is visible down to these depths, proves, that a low post-depositional heat flow was present in the DDB. This is in good agreement with vitrinite reflectance measurements and thermal modelling results from previous studies, which suggest a low Mesozoic heat flow.</p></abstract>ARTICLE2018-09-06T00:00:00.000+00:00The Sarmatian/Pannonian boundary at the western margin of the Vienna Basin (City of Vienna, Austria)<abstract><title style='display:none'>Abstract</title><p> Sarmatian and Pannonian cores, drilled at the western margin of the Vienna Basin in the City of Vienna, reveal a complex succession of marine and lacustrine depositional environments during the middle to late Miocene transition. Two Sarmatian and two Pannonian transgressive-regressive sequences were studied in detail. Identical successions of benthic faunal assemblages and similar patterns in magnetic susceptibility logs characterise these sequences. This allows a correlation of the boreholes over a distance of ~3.5 km across one of the major marginal faults of the Vienna Basin. Biostratigraphic data, combined with rough estimates of sedimentation rates, reveal large gaps between these sequences, suggesting that only major transgressions reached this marginal area. In particular, during the Sarmatian-Pannonian transition, the basin margin completely emerged and turned into a terrestrial setting for at least 600 ka.</p></abstract>ARTICLE2018-09-06T00:00:00.000+00:00Facies, palaeogeography and stratigraphy of the lower Miocene Traisen Formation and Wildendürnbach Formation (former “Oncophora Beds”) in the Molasse Zone of Lower Austria<abstract><title style='display:none'>Abstract</title><p> A detailed study of OMV wells throughout the Lower Austrian Molasse Basin demonstrates the existence of a distinct and synchronous upper Ottnangian (lower Miocene) stratigraphic signal, the Calcite Minimum Interval (CMI). It corresponds to the depositional phase of the Rzehakia Lake System. This signal is interpreted to be of chronostratigraphic importance as an expression of palaeoclimate and related sea-level change. It is represented by the brackish Traisen Formation, which crops out south of the Danube. The Traisen Formation correlates with sands and shales in OMV wells to the north, termed Wildendürnbach Formation. However, the CMI underlies a marine unit, the so-called “Oncophora Beds” (also known as Rzehakia Beds) as reported from OMV wells in the north at the border to the Czech Republic. We demonstrate that these former “Oncophora Beds” are younger, i.e. of Karpatian age, than originally assumed. Therefore, these deposits cannot be correlated to the late Ottnangian Traisen Formation. This may solve the problem of contradicting interpretations concerning the depositional environment of both units, which were correlated to each other in the past. As no Rzehakia bivalves (formerly Oncophora) are described from these former “Oncophora Beds”, we recommend to avoid using the term for these turbiditic sands. Instead, we attribute these deposits to the fully marine Karpatian Laa Formation. These new findings, which are in accordance with published data from the Czech Republic, indicate two (in time and space) independent sedimentary systems and sand deposition centres for the Traisen Formation and the massive sands attributed as “Oncophora Beds” around Wildendürnbach. A late Ottnangian system in the south delivered the material of the Traisen Formation from the Alps and a Karpatian system delivered the clastic material of the massive sands of the Laa Formation from the east.</p></abstract>ARTICLE2018-09-06T00:00:00.000+00:00The benthic foraminifer (Reuss, 1862): Taxonomic review and ecological insights<p>The benthic foraminifer <italic>Rosalina binkhorsti</italic> Reuss, 1862, was cosmopolitan in Late Cretaceous to early Paleogene shallow-water seas. It possesses a distinctive composite wall made of a continuous, agglutinated layer discontinuously covered by secondary hyaline outer deposits. Its taxonomic position, phylogeny, morphology, wall structure, and composition have been debated for a long time. Based on abundant, well-preserved material from the Danian of the Kambühel Formation in the Northern Calcareous Alps, Austria, we identify elements in the here emended species <italic>Stomatorbina binkhorsti</italic> which support a strong affinity to the order Textulariida, within the genus <italic>Stomatorbina</italic> Dorreen, 1948. Usually regarded as free (non-fixing), <italic>S. binkhorsti</italic> is here illustrated attached to small bioclasts in high-energy carbonate settings. The attached specimens are juvenile forms with a wall covered by massive hyaline deposits. This observation suggests that secondary lamellar parts added to the wall may have served for stabilisation or fixation to the substrate.</p>ARTICLE2019-12-31T00:00:00.000+00:00Evidence for pre-Pleistocene landforms in the Eastern Alps: Geomorphological constraints from the Gurktal Alps<p>We present evidence for a series of pre-Pleistocene landforms on hand of a new geomorphological map for the Gurktal region of the Eastern Alps. The Gurktal Alps region is the westernmost region of the Eastern Alps that escaped the glacial reshaping in the Pleistocene. Its morphology therefore preserves evidence of older landforms in closer proximity to the central part of the range than any other region in the Alps. The region is therefore useful to document aspects of the geomorphological evolution for the Eastern Alps during both, the Pleistocene glaciations and the earlier uplift history. Our mapping approach is twofold. We applied stream-power analysis outside the glacially overprinted areas to detect and classify spatially distinct quasi-stable stream segments, which we expanded to planar objects using slope analysis combined with field mapping. Our mapping results document four palaeo-surfaces located roughly at about 1500 m, 1200 m, 900 m and about 800 m above sea level. We correlate these levels with well-known palaeo-surfaces from the eastern end of the Alps and suggest that they can be interpreted in terms of more than 1000 m of surface uplift in the last six million years. Channel analysis and the distribution of Pleistocene gravel terraces suggest that the main trunk of the river Gurk was diverted from the Wimitz valley in the Rissian. Furthermore, steam-power analysis documents an ongoing activity of the Görschitztal fault and some inferred Pleistocene activity of a north-west trending fault close to the township of Gurk.</p>ARTICLE2019-11-20T00:00:00.000+00:00On the magnitude and possible return period of the historical earthquake in ancient Savaria, 455 AD (Szombathely, West Hungary)<p>In 455 AD a strong, presumably M ≥ 6.0, earthquake occurred in or near the ancient town Savaria, the present Szombathely, West Hungary. According to the certainly incomplete earthquake catalogue, since then no similar significant seismic event occurred during the last 1500 years in this area which is currently considered inactive. Conclusions of this study are: (1) According to contemporary written historical sources (<italic>Annales Ravennates</italic> and biographical information about the life of Saint Severinus), the earthquake that destroyed Savaria and occurred in 455 AD had a magnitude of M ≥ 6.0. (2) In order to support the aforementioned magnitude value calculations were necessary. As the historical seismicity of the area is not known sufficiently an independent geodynamical approach – in parallel to the Gutenberg-Richter relationship – was used to estimate the return interval of earthquakes M ≥ 6. It was found in both cases that in the Szombathely region the recurrence time of earthquakes M6 and M6.5 is 1000 and 3000 years. Consequently, the earthquake activity of the Szombathely region is significantly lower than that of the Pannonian Basin in general.</p>ARTICLE2019-12-31T00:00:00.000+00:00Integrated stratigraphy of the Guşteriţa clay pit: a key section for the early Pannonian (late Miocene) of the Transylvanian Basin (Romania)<p>The Neogene Transylvanian Basin (TB), enclosed between the eastern and southern Carpathians and the Apuseni Mountains in Romania, is a significant natural gas province with a long production history. In order to improve the (bio) stratigraphic resolution, correlations and dating in the several 100-m-thick upper Miocene (Pannonian) succession of the basin, the largest and most fossiliferous outcrop at Guşteriţa (northeastern part of Sibiu) was investigated and set as a reference section for the <italic>Congeria banatica</italic> zone in the entire TB. Grey, laminated and massive silty marl, deposited in the deep-water environment of Lake Pannon, was exposed in the ~55-m-high outcrop. The uppermost 25 m of the section was sampled in high resolution (sampling per metres) for macro- and microfossils, including palynology; for authigenic <sup>10</sup>Be/<sup>9</sup>Be dating and for magnetostratigraphy; in addition, macrofossils and samples for authigenic <sup>10</sup>Be/<sup>9</sup>Be isotopic measurements were collected from the lower part of the section as well. The studied sedimentary record belongs to the profundal <italic>C. banatica</italic> mollusc assemblage zone. The upper 25 m can be correlated to the <italic>Hemicytheria tenuistriata</italic> and <italic>Propontoniella candeo</italic> ostracod biozones, the uppermost part of the <italic>Spiniferites oblongus</italic>, the entire <italic>Pontiadinium pecsvaradense</italic> and the lowermost part of the <italic>Spiniferites hennersdorfensis</italic> organic-walled microplankton zones. All samples contained endemic Pannonian calcareous nannofossils, representing the <italic>Noelaerhabdus bozinovicae</italic> zone. Nine samples were analysed for authigenic <sup>10</sup>Be/<sup>9</sup>Be isotopic measurements. The calculated age data of six samples provided a weighted mean value of 10.42 ± 0.39 Ma. However, three samples within the section exhibited higher isotopic ratios and yielded younger apparent ages. A nearly twofold change in the initial <sup>10</sup>Be/<sup>9</sup>Be ratio is a possible reason for the higher measured isotopic ratios of these samples. Magnetostratigraphic samples showed normal polarity for the entire upper part of the outcrop and can be correlated with the C5n.2n polarity chron (11.056–9.984 Ma, ATNTS2012), which is in agreement with the biostratigraphic data. Based on these newly obtained data and correlation of the biozones with other parts of the Pannonian Basin System, the Guşteriţa section represents the ~ 11.0–10.5 Ma interval, and it is a key section for correlation of mollusc, ostracod, dinoflagellate and calcareous nannoplankton biostratigraphic records within this time interval.</p>ARTICLE2019-12-31T00:00:00.000+00:00The Alland earthquake sequence in Eastern Austria: Shedding light on tectonic stress geometry in a key area of seismic hazard<p>We present our results on the fault geometry of the Alland earthquake sequence in eastern Austria (Eastern Alps) and discuss its implications for the regional stress regime and active tectonics. The series contains 71 known events with local magnitudes 0.1 ≤ <italic>M</italic><italic><sub>L</sub></italic> ≤ 4.2 that occurred in between 2016 and 2017. We locate the earthquakes in a regional 3D velocity model to find absolute locations. These locations are then refined by relocating all events relative to each other using a double-difference approach, based on relative travel times measured from waveform cross-correlation and catalogue data. We also invert for the moment tensor of the <italic>M</italic><italic><sub>L</sub></italic> = 4.2 mainshock by fitting synthetic waveforms to the recorded seismo-grams using a combination of the L1- and L2-norms of the waveform differences. Direct comparison of waveforms of the largest events in the sequence suggests that all of them ruptured with very similar mechanisms. We find that the sequence ruptured a reverse fault, that is dipping with ~30° towards ~north-northeast (NNE) at 6–7 km depth. This is supported by both the hypocentres and the mainshock source mechanism. The fault is most likely located in the buried basement of the Bohemian massif, the “Bohemian Spur”. This (reverse) fault has a nearly perpendicular orientation to the normal-fault structures of the Vienna Basin Transfer Fault System further east at a shallower depth, indicating a lateral stress decoupling that can also act as a vertical stress decoupling in some places. In the west, earthquakes (at a larger depth within the upper crust) show compressive stresses, whereas the Vienna Basin to the east shows extensional (normal-faulting) stress. This provides insight into the regional stress field and its spatial variation, and it helps to better understand earthquakes in the area, including the “1590 Ried am Riederberg” earthquake.</p>ARTICLE2019-12-31T00:00:00.000+00:00The 1906 Dobrá Voda Earthquake (M=5.7) at the Vienna Basin Transfer Fault: evaluation of the ESI2007 intensity and analysis of the aftershock sequence<p>Aftershock identification plays an important role in the assessment and characterization of large earthquakes. Especially, the length of the aftershock sequence is an important aspect of declustering earthquake catalogues and therefore impacts the frequency of earthquakes in a certain region, which is important for future seismic hazard assessment. However, in intraplate regions with low deformation rates and low to moderate seismicity, it is still questionable if aftershocks after a major event may continue for much longer time. In this study, we use one of the earliest instrumentally recorded earthquakes, the 1906 Dobrá Voda earthquake (Ms/I<sub>max</sub>=5.7/VIII-IX), to compare different approaches of aftershock determination and their suitability for understanding the recorded earthquake sequence. The Dobrá Voda segment of the Vienna Basin Transfer Fault System is one of the seismically most active zones in Slovakia with the 1906 earthquake as the strongest recorded earthquake. We first assess the epicentral intensity of the earthquake according to the Environmental Intensity Scale (ESI2007) using contemporary descriptions of earthquake effects. This additional information leads to constrain the maximal intensity to IESI2007=IX. This result agrees well with first the assessment of Imax in 1907 and indicates the reliability of this intensity data. In the second step, earthquake data are plotted for two spatial windows extending 13 km and 26 km from the epicenter of the mainshock, respectively. Despite uncertainties regarding the completeness of data due to war times and lack of nearby seismic stations, the overall temporal evolution of seismicity can apparently not be described as an Omori-type aftershock sequence following the event in 1906. Instead, earthquake occurrence within 13 km of the mainshock shows elevated earthquake activity right after the 1906 event that only decays to a lower level of activity within decades after the mainshock. The decline of seismicity therefore occurs over time scales which are much longer than those predicted by the Omori relation. We conclude that today’s seismic activity may still be affected by the 1906 earthquake.</p>ARTICLE2020-07-13T00:00:00.000+00:00Clay mineralogy of Miocene mudstones from the Lower Austrian Molasse Basin<p>Recent studies established the lithological and chemical sediment evolution in the Lower Austrian Molasse Basin (LAMB), a part of the North Alpine foreland basin, during the Early Miocene. In this study, we aim to integrate the clay mineralogy of seven wells across the LAMB with a newly proposed lithostratigraphy, and to infer implications for provenance, palaeo-geography and palaeoclimate. The results of our qualitative and quantitative evaluation of the clay-sized fraction with x-ray diffractometry largely support the stratigraphic model. The early stage of foreland basin formation (Egerian/Eggenburgian?) is represented by kaolinite contents up to 93 % in the clay sized fraction. This indicates an orogen-external source, i.e. the Bohemian Massif, and erosion of intensively chemical weathered products during this early Molasse basin stage. The over-lying marine Robulus Schlier (lower/middle Ottnangian) is characterized by a distinctly reduced kaolinite content and overall increased illite content compared to the other formations. Illite was predominantly provided from denudation of the rising Eastern Alps, i.e. characterizing the orogen-internal provenance. The pelites of the overlying carbonate poor Traisen Formation (upper Ottnangian) show again a higher kaolinite and smectite content. In the largely coeval basinal Wildendürnbach Formation, smectite reaches up to 70 % in the clay sized fraction. Peak smectite values may be linked to volcanic ash input from the nearby Carpathian volcanic arc. Generally rising smectite versus illite ratios during the Ottnangian-Karpatian could point to a warming and intensified chemical weathering of the rising Alpine orogen.</p>ARTICLE2020-10-15T00:00:00.000+00:00The presence of elk () in Austria since the upper Pleistocene<p>This study reports new data on the occurrence of elk remains in the western, mountainous part of Austria and also provides a compilation of all currently known 107 elk finds of the upper Pleistocene to upper Holocene in this country. The altitudinal distribution reveals two maxima for Austria: a lower one at about 400 m a.s.l., which comprises the alpine foreland, and a second one at about 1600-1800 m a.s.l., reflecting the abundance of vertical caves in the Northern Calcareous Alps at this elevation (animal traps). Vorderkarhöhle in Tyrol is the highest known elk find in Austria (1860 m a.s.l.), interestingly located above the tree line. Although only 11% of all elk sites in Austria have been radiocarbon-dated, stratigraphic and archaeo-logical constraints allow to assign 90% of those sites that lack radiometric dating to either the upper Pleistocene (18%) or the Holocene (72%). Among the latter, upper Holocene sites dominate (78%), followed by middle (16%) and lower Holocene (6%) sites. The youngest radiocarbon-dated elk find in Austria is from Gaflein Valley (Tyrol, 1285-1359 cal BP), in agreement with data from the Swiss Alps, showing that the elk survived beyond Roman times in the Alps and became extinct before the onset of the Middle Ages.</p>ARTICLE2020-09-03T00:00:00.000+00:00Is hydrotectonics influencing the thermal spring in Eisensteinhöhle (Bad Fischau, Lower Austria)?<p>Eisensteinhöhle is a 2 km long crevice cave that is significantly overprinted by hydrothermal karst processes. It was opened during quarrying in the Fischauer Vorberge, at the western margin of the Vienna Basin. This pull-apart basin cuts the eastern foothills of the Alps and is formed by a major NE-SW striking, sinistral transform fault. The western margin consists of NNE-SSW striking normal faults creating paths for thermal water to rise from the central basin. The deepest part of the cave, 73 m below the entrance, hosts a pond with 14.6 ±0.2 °C warm water that occasionally acts as a spring. The water level and temperature fluctuate and at a certain level, water visibly discharges into a nearby narrow fissure. As sporadic observations of the water level since 1992 gave no obvious connection to precipitation events, the connection to an aquifer and the origin of the water remained unknown. A pumping test, conducted on 13/7/2016, yielded a volume of the spring/pool of about 2.8 m<sup>3</sup> that is fed by a very small inlet at the sandy bottom. At the time of the pumping test, the discharge was only 4.5 l/h but during previous overflow events, discharge values of up to 289 l/h were recorded.</p>ARTICLE2019-12-31T00:00:00.000+00:00en-us-1