rss_2.0Austrian Journal of Earth Sciences FeedSciendo RSS Feed for Austrian Journal of Earth Sciences Journal of Earth Sciences Feed Levels in the Dachstein Massif (Eastern Alps)<abstract> <title style='display:none'>Abstract</title> <p>This paper investigates the vertical distribution of horizontal and subhorizontal cave passages in the Dachstein Massif of Austria. Cave passages that are confined to vertical ranges, so-called cave levels, can be correlated with former valley floors and thus reflect tectonically and climatically stable periods. Previous studies analyzed significant karst Massifs (or parts of them) in the Northern Calcareous Alps but have excluded the Dachstein massif so far. The Dachstein is the second largest massif in the area, contains many extensive caves, and plays a key role in reconstruction of landscape evolution (“Dachstein surface”). In contrast to some previous works, we aimed to analyze only passages that formed (or are forming) under phreatic or epiphreatic conditions (i.e. permanently or episodically water-filled). This genetic classification is based on field observations, cave maps, 3D survey shots and descriptions. For this study, 789 caves with a total length of 279 km were considered, but data were only available for 599 caves (276 km). Only 25% of all caves in the Dachstein Massif are at least partly of (epi)phreatic origin, but the total length of phreatic passages is 204 km. Altitudes of the phreatic sections of each cave were grouped in 25-m increments and plotted according to their phreatic passage length. It turned out that there are five vertical accumulations of caves in the Dachstein Massif. Despite some previous studies that also considered morphological, hydrological, and sedimentological characteristics, our correlation with the “classical” supra-regional cave levels in other karst massifs was based only on elevation. The following elevations for the cave levels were determined: Spring Cave Level: 475-775 m a.s.l., Berger Cave Level: 825-1075 m, Giant Cave Level (with the highest peak): 1125-1550 m, Ruin Cave Level: 1600-2050 m, and a formerly unknown level at 2525-2750 m, for which we propose the name Voodoo Cave Level. According to this study the two longest cave systems, the Hirlatzhöhle (114 km long and 1560 m deep) and the Dachstein-Mammuthöhle (68 km, 1207 m) are most relevant for the result. The local vertical distribution of caves within the Dachstein was compared with the regional northward tilt of cave levels in the Northern Calcareous Alps, however the heterogeneous distribution of the known cave obscures local effects in the Dachstein Massif.</p> </abstract>ARTICLEtrue new guideline for geological maps with QGIS<abstract> <title style='display:none'>Abstract</title> <p>Being able to create digital geological maps has become a basic requirement for the skillset of today’s geologists. QGIS is a geographical information system that receives increasing popularity due to its user-friendliness and the fact that it is an open access software. This contribution provides an update and extension to a previously published software guideline that gives a stepwise explanation on how to create a geological map with QGIS. The article serves as a brief overview of the guideline through an illustrated example. The guideline itself is published as a supplement to this paper. Within six sections, the guideline explains how to create a geological map with QGIS: 1. Introduction, 2. Download and installation, 3. Basemaps, 4. Map drawing, 5. Plugins, 6. Layouts. The aim is to instruct geologists who are completely inexperienced with digital map creation as well as provide specific information for more advanced users. In general, providing software guidelines for the geological community is an important step towards increasing geologists’ digital proficiency and to keep up with today’s fast paced developments in digitalization.</p> </abstract>ARTICLEtrue analysis of karst springs in Lower Austria<abstract> <title style='display:none'>Abstract</title> <p>Karst springs play a central role in Austria’s water supply. This paper aims to provide an overview of the karst springs of Lower Austria, analysing statistical correlations of spatial distribution, discharge, electrical conductivity (EC), and temperature. As part of a project with the provincial government of Lower Austria, older data from numerous studies have been combined with the self-generated data in a GIS database. This database contains data on 2056 karst springs. Most of the recorded springs are located in the Northern Calcareous Alps, although karst springs also occur in the Central Alpine Permomesozoic, the Waschberg zone and the Bohemian Massif, some of which are also of regional importance for drinking water supply. Chemical analyses show that limestone, dolomite and mixed springs are widespread in Lower Austria and occur with similar frequency. Gypsum springs, which are characterised by a significantly higher total mineral-isation, are also of regional importance. The statistical analysis shows that spring water temperatures correlate well with the mean annual air temperature at the mean catchment elevation. The temperature decrease with increasing elevation corresponds to the air temperature gradient in the Eastern Alps (0.47 °C/100 m). In addition, the springs show a negative correlation of the EC with the mean catchment elevation, which can be explained by a decrease in soil cover and thus reduced CO<sub>2</sub> uptake of the water, as well as dilution by rainwater. This leads to less carbonate dissolution, which is also reflected in less HCO<sub>3</sub><sup>−</sup> contents. Corrected for the elevation effect, the investigated dolomite springs, have on average a 2.7% higher EC than limestone springs. A difference was also found between the Hauptdolomit and the Wettersteindolomit rock types, which are widespread in Lower Austria, with the latter displaying higher values on average by 2.2%. This indicates longer residence times of the spring water due to less karstification of the Wettersteindolomit.</p> </abstract>ARTICLEtrue Lower - Middle Miocene transition (Karpatian – Badenian) in the Krems Embayment (Central Paratethys, Lower Austria): a multistrati-graphic approach and the role of the Diendorf-Boskovice Fault System.<abstract> <title style='display:none'>Abstract</title> <p>The Krems Embayment contains the westernmost fully marine depositional environments of the Karpatian and Bade-nian transgressions in the Central Paratethys. Four drill cores were investigated to analyse the bio- and lithostratigraphic, and tectonic relations. The investigated core sections cover the Karpatian Laa Formation (bio-zones M4, NN4) and the Badenian Gaindorf Formation (M5b-M6, NN4-NN5). Important biostratigraphic indicators identified are <italic>Praeorbulina glomerosa glomerosa, Praeorbulina glomerosa circularis</italic> and <italic>Orbulina suturalis</italic> for the Gaindorf Formation. The Laa Formation is indicated by the absence of <italic>Praeorbulina</italic>, <italic>Orbulina</italic> and <italic>Globigerina falconensis</italic>, low numbers of <italic>Globorotalia bykovae</italic>, and a prominent peak in <italic>Helicosphaera ampliaperta</italic> abundance at the end of the Karpatian. <italic>Cibicidoides lopjanicus</italic> and <italic>Cassigerinella</italic> spp. occur with high percentages in Badenian samples and show much longer stratigraphic ranges than known from literature data. The depositional gap at the Karpatian-Badenian boundary has a minimum duration of 0.41 My in the Krems Embayment. The combination of bio- and lithostratigraphic data allows the correlation across major faults. The Diendorf-Boskovice Fault System played an important role during basin formation and was identified as very active during the early to middle Badenian Stage. The results of this study show the complex interaction of sedimentation, tectonic activity and paleobiological developments in this peripheral part of a marginal sea.</p> </abstract>ARTICLEtrue role of the proto-Alpine Cenerian Orogen in the Avalonian- Cadomian belt<abstract> <title style='display:none'>Abstract</title> <p>The proto-Alpine Cenerian orogen (Ediacaran-Ordovician) and the Cadomian orogen (Ediacaran-Cambrian), remnants of which are exposed in the central European Variscides, should be defined as two distinct and spatially separated coastal orogens within the Avalonian-Cadomian belt. The Cadomian orogen originally lay in front of the Sahara metacraton. It underwent a change from an active to a passive margin setting during the Cambrian. The Cenerian orogen, represented by intra-Alpine rocks, was located farther east near the Arabian Nubian Shield, from where it inherited a characteristic Tonian/Stenian detrital zircon signal. Subduction persisted in the Cenerian Orogen until the Ordovician. The Cadomian orogen was akin to Andean type whereas the Cenerian orogen was more akin to Alaskan type. This paper explores why the two orogens have such different characteristics and tectonic evolutions despite their probable proximity in the Avalonian-Cadomian belt. One explanation could be that they were at nearly right-angles to each other due to a strong concave bending of the northern Gondwana margin ahead of the Arabian-Nubian Shield.</p> </abstract>ARTICLEtrue orogen – young topography: Evidence for relief rejuvenation in the Bohemian Massif<abstract> <title style='display:none'>Abstract</title> <p>The Bohemian Massif is the relic of a major Paleozoic mountain range that is known to have exhumed and its surface levelled in the Permian, but its Neogene landscape evolution is largely unconstrained. The landscape is characterized by rolling hills and extended planation surfaces above an elevation of about 500 m. However, at lower elevations deeply incised gorges confined by steep hillslopes are abundant and contrast impressively with the low relief landscapes above. Rivers with a bimodal morphology (i.e. steep at lower elevations and gentle at higher elevations) drain either to the north into the Vltava (Moldau) River or to the south into the Danube River. Hence, a continental drainage divide runs through the Bohemian Massif. Here, we quantify spatial characteristics of the Bohemian Massif landforms by computing landscape metrics like steepness index or geophysical relief derived from digital elevation models. From this we infer temporal change of the landscape in the past and predict them for the future evolution of the region.</p> <p>We show that the landscape is characterized by out-of-equilibrium river profiles with knickpoints abundantly at elevations between 450 m and 550 m separating steep channel segments at lower elevations from less steep channels at higher elevations. Hypsometric maxima at or close above knickpoint elevations, along with high and low values in geophysical relief as indicator for the degree of fluvial landscape dissection downstream and upstream of major knickpoints, support the idea of landscape bimodality. Furthermore, we find a distinct drainage divide asymmetry, which causes the reorganization of the drainage network of the region. Across-divide gradients in channel steepness predict the northward migration of the Danube-Vltava drainage divide including growth and shrinkage of tributary catchments, thus controlling changes in the Central European drainage pattern.</p> <p>All aspects suggest that the region experienced relief rejuvenation during the last few million years. We suggest that this relief rejuvenation is related to the inversion of the Molasse basin with a long wavelength rock uplift pattern and low uplift rates. Vertical motion of crustal blocks at discrete faults may locally affect the uplift pattern. However, the contrasting bedrock properties between the sedimentary cover (Molasse sediments) and the crystalline basement (Bohemian Massif) cause substantial differences in erosion rate and are thus the superior control on the topographic variations of the entire region.</p> </abstract>ARTICLEtrue temporal evolution of seismicity and variability of b-values along the Vienna Basin Transfer Fault System<abstract> <title style='display:none'>Abstract</title> <p>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.</p> <p>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.</p> <p>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.</p> <p>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.</p> </abstract>ARTICLEtrue geochemistry and petrography of Miocene ombrotrophic coals in the tropical Asem-Asem Basin (Kalimantan, Indonesia): Comparison to coeval subtropical coals in the Eastern Alps<abstract> <title style='display:none'>Abstract</title> <p>The middle Miocene Warukin Formation in the Asem-Asem Basin (Kalimantan) contains a 20-m-thick coal seam (BL1) that is mined at the Jumbang mine. The seam, formed in a tropical peat, was studied to reconstruct the peat-forming environment and to compare its characteristics with those of similarly aged tropical coals from the Tutupan mine in the Barito Basin (Kalimantan) and similarly aged (<sup>~</sup>15 Ma) subtropical coal from the Leoben Basin in the Eastern Alps (Austria). Although all coals were formed in ombrotrophic peatlands, the comparison reveals differences in biomarker and maceral composition due to the different climate and flora.</p> <p>The study is based on 22 coal and three non–coal samples, each representing a stratigraphic interval of 0.2 to 1.0 m. The samples were analyzed for ash yield, carbon and sulphur contents, and maceral composition. Organic geochemical parameters were obtained on eight coal samples to obtain information on the peat-forming vegetation. The low-ash, low-sulphur BL1 seam was deposited in an ombrotrophic basinal (coastal) mire. Locally increased sulphur contents in the lower coal bench BL1L demonstrate brackish influence and a near-shore environment. The vegetation was dominated by angiosperms including abundant dammar resin producing <italic>Dipterocarpaceae</italic>, while the contribution of gymnosperms was negligible.</p> <p>The Tutupan seams T110 and T210, which were formed in kerapah (inland) ombrotrophic mires, have similar ash yields and sulphur contents but contain higher, although still low, concentrations of gymnosperm-derived diterpenoids. In addition, lower amounts of cadinane-type biomarkers and resinite suggest that <italic>Dipterocarpaceae</italic> were less dominant in kerapah peats. While differences between tropical coals from Kalimantan are minor, major differences exist between the tropical coals and the subtropical ombrotrophic Leoben coal. These include significantly higher concentrations of gymnosperm-derived biomarkers in subtropical peat, lower amounts of resinite due to the absence of <italic>Dipterocarpaceae</italic>, as wells as lower amounts of leaf- and rootlet-derived macerals. Apparently, fungal activity was also reduced in the sub-tropical Leoben peat. Surprisingly, the average amount of oxidized plant remains is also lower in the subtropical peat.</p> </abstract>ARTICLEtrue remote sensing prospection of Miocene limestone quarries in the hinterland of Roman Carnuntum and Vindobona (Vienna Basin, Austria)<abstract> <title style='display:none'>Abstract</title> <p>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).</p> <p>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), “<italic>Gruibert</italic>” in Winden am See (Burgenland) and “<italic>Hoher Berg</italic>” 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.</p> </abstract>ARTICLEtrue regional scale Cretaceous transform fault zone at the northern Austroalpine margin: Geology of the western Ammergau Alps, Bavaria<abstract> <title style='display:none'>Abstract</title> <p>We reinvestigated parts of the northern Austroalpine margin and provided structural and kinematic field data in order to interpret the kinematic relationship between the Cenoman-Randschuppe (CRS) marginal slice, Falkensteinzug (FSZ), Tannheim- and Karwendel thrust sheets occurring in a narrow strip at the northern front of the northwestern Northern Calcareous Alps (NCA). As a consequence, we propose a revised model for the tectonic evolution of the northern Austroalpine margin. As thrusting propagates from SSE to NNW (Cretaceous orogeny), the Karwendel thrust sheet (including its frontal part, the FSZ) was emplaced onto the Tannheim thrust sheet in the Albian, deduced from (i) upper-footwall deposits, the youngest sediments below the Karwendel thrust (Tannheim- and Losenstein Fms.), and (ii) thrust-sheet-top deposits unconformably overlying the deeply eroded northern Karwendel thrust sheet (Branderfleck Fm.). The future CRS marginal slice was, at that time, part of the foreland of this Early Cretaceous Alpine orogenic wedge. Pervasive overprint by sinistral shear within the CRS marginal slice and northern Tannheim thrust sheet suggests sinistral W-E striking transform faults cutting across this foreland, decoupling CRS marginal slice and FSZ from the main body of the NCA and enabling an independent evolution of the CRS marginal slice from the Early Cretaceous onwards. Subsequent Late Cretaceous and younger shortening leads to successive incorporation of Arosa zone, Rhenodanubian Flysch (RDF) and Helvetic units into the Alpine nappe stack; the Tannheim thrust representing the basal thrust of the NCA. Growth strata within thrust-sheet-top deposits (Branderfleck-Fm.) give evidence for refolding of thrust sheet boundaries. In a typical thin-skinned fold-and-thrust belt, deformation should cease towards the thrust front, whereas within the NCA it increases. An Austroalpine thrust front controlled by E-trending transform faults could cause an increase in deformation towards the most external NCA and explain the absence of the Arosa zone between Allgäu and Vienna. Such faults would most probably also cut out Lower Austroalpine units. Therefore, RDF and CRS marginal slice are juxtaposed; the latter found in the tectonic position of the Arosa zone. The presence of transform faults underlines the strong imprint of the opening of the North Atlantic Ocean on the depositional setting and tectonic evolution of the NCA.</p> </abstract>ARTICLEtrue architecture of a mixed clastic-carbonate succession and Sr/Sr-based chronostratigraphy along the margin of a synorogenic extensional basin (Hochmoos Formation, upper Santonian, Northern Calcareous Alps)<abstract> <title style='display:none'>Abstract</title> <p>The Gosau Group (Turonian to Ypresian) of the Eastern Alps is a synorogenic wedge-top succession that accumulated in active depocenters in an oblique-convergent plate tectonic setting. Due to high morphological differentiation of depocenters by tectonism, the Gosau Group displays a wide range of facies as well as marked facies heteropy and thickness variations over short lateral distances. In the area of the locations Gosau and Russbach, the Hochmoos Formation along the SE basin margin near Gosauschmied comprises coastal to shallow-marine deposits and small rudist bioconstructions and was investigated by way of field mapping, profile descriptions, microfacies analysis, isotope measurements and assessment of fossil content.</p> <p>Strontium isotope ratios (<sup>87</sup>Sr/<sup>86</sup>Sr) from 0.707485 (oldest) to 0.707549 (youngest) indicate a latest Santonian age, with the youngest parts of the Hochmoos Formation possibly extending into the Campanian. On the west side of the study area, the succession of lithologies and fossil content record transgression of a fan-delta to marginal-marine environment (lowstand to transgressive systems tract), followed by shallow neritic deposition (part of the transgressive systems tract) and, finally, by progradational stacking of limestone beds in the highstand systems tract, culminating in growth of rudist thickets in an inner shelf and partially protected ‘lagoonal’ milieu. Eventually, at the inception of the following falling stage systems tract, input of large clasts of Dachstein Limestone, quartz and chert record a recurrence of the subaqueous part of a fan-delta. On the east side of the study area, a preponderance of rudist-clastic limestones over a few rudist biostromes preserved <italic>in situ</italic> indicate a normal-marine environment punctuated by high-energy events, such as storms or tsunami. The scarcity of benthic foraminifera and the presence of only isolated specimens of colonial corals underscore a habitat with a calcarenitic substrate frequently shifted by currents. Several lines of evidence indicate that the western part of the study area was more proximal relative to the eastern one. With a maximum thickness of 68 m, the Hochmoos Formation at Gosauschmied is slightly thicker and more distal than outcrops located nearer to the basin margin and farther towards the SE (Schmiedsippl, Katzhofgraben), but significantly thinner than the nearly 300 m at Gosau Pass-Gschütt, or the thickness of 170 m observed in the area of Rigaus-Abtenau farther in the West. These thickness variations are interpreted as a result of extensional syndepositional tectonism. At Gosauschmied, the vertical arrangement of facies records a cycle of relative sea-level change that may have been tectonically enhanced.</p> </abstract>ARTICLEtrue of the Dachstein Limestone in the Dachstein thrust sheet (Eastern Alps, Austria)<abstract> <title style='display:none'>Abstract</title> <p>Deformation affecting the Upper Triassic Dachstein Limestone has been analyzed in the Dachstein thrust sheet, the uppermost thrust unit of the central Northern Calcareous Alps (Eastern Alps). Different scales of deformation are discussed, from kilometer-scale thrusting down to folds in the order of tens of meters to meters. Observations are based on both conventional outcrop observations and on digital fieldwork performed on drone-captured virtual outcrops and on GoogleMaps 3D terrain renderizations. The structures observed were formed at different times and document the following events: 1) Late Triassic syn-depositional instability and slumping; 2) Late Triassic syn-depositional growth of the Hallstatt diapir; 3) Late Triassic syn-depositional, salt-driven, extensional faulting; 4) Jurassic-age re-activation of extensional faults; 5) (presumably) Early Cretaceous shortening in both east-west and north-south directions; and 6) (presumably) Late Cretaceous extensional re-activation of faults. The structures and their origin have a bearing on the interpretation of the tectonic evolution of the Dachstein thrust sheet, highlighting the potential relevance of salt tectonics in controlling its structure.</p> </abstract>ARTICLEtrue of alpine lakes in the Northern Calcareous Alps: a comparative study on the role of groundwater in Filblingsee and Eibensee<abstract> <title style='display:none'>Abstract</title> <p>In the Northern Calcareous Alps (NCA) there are countless small lakes with small orographic catchments that are often located only slightly below the respective summit regions. On the one hand, the lakes are located in karstable aquifers and their existence is likely to be related to karstification. Then, they are expected to be directly connected to the karst water body. These lakes are classified as karst lakes. On the other hand, the alpine environment is also influenced by glacial processes and lakes might be related to glacial erosion and deposition. For these glacial lakes, the share of groundwater inflow and outflow is regarded as subordinate even within high permeable karst lithologies. Here we compare two alpine lakes of potentially different origin in the NCA in Salzburg with the aim to provide a basis for an aerial survey of the numerous small alpine lakes in the NCA region and their characterization using the guiding parameters elaborated here. We consider (a) the lake geometry, (b) potential inflow and outflow systems, and (c) physicochemical parameters and hydrochemistry of the Filblingsee and the Eibensee, both located in the Fuschlsee region. Filblingsee was initially considered as a typical karst lake and Eibensee as a moraine-dammed glacial lake. Some clear differences arise in lake geometry, which in the karst lake shows a nearly round surface and concentric depth profile, while the glacial lake is elongated in the direction of glacier flow and has the deepest areas just upstream of the moraine dam. Both lakes show very little to no surficial inflow. Inflow and outflow occur in groundwater in both cases but are not directly tied to a highly permeable karst system. The depth profiles of the field parameters of the two lakes differ only slightly and show a dominant groundwater inflow in mid-depth regions but no flow through at the lake bottom. Water chemistry in both lakes and their potential outflows correspond to the respective aquifer in terms of solution load. Filblingsee can be characterized as a hanging lake in a secondarily sealed doline, Eibensee lies in a glacially excavated depression sealed by glacial sediments. While the inflow and outflow conditions and the hydrochemistry of both lakes are very similar, the lake geometry is a clear distinguishing feature that can be attributed to the different genesis of the two lakes. This can therefore be used as a guiding parameter for the classification of the numerous small alpine lakes in the NCA.</p> </abstract>ARTICLEtrue shallow into deep sea: Sedimentary facies and U-Pb zircon ages in the early Paleozoic Noric Group at Veitsch (Eastern Greywacke Zone, Austria)<abstract> <title style='display:none'>Abstract</title> <p>The low-grade metamorphic early Paleozoic basement of the Veitsch area presents a wide variety of sedimentary facies domains. The first domain consists of thick metadacites of Middle Ordovician age (Blasseneck Porphyroid), overlain by fine-grained metaclastics of the Rad Formation (Late Ordovician to Silurian) and Devonian limestones and calcitic marbles (Kaiserstein and Kaskögerl Formation, respectively). Rhyolitic to dacitic magmatism initiated at ca. 479 Ma (LAMC-ICP-MS U-Pb zircon data) and lasted until ca. 444 Ma. The second domain comprises metaclastics of the Stocker Formation (Early Ordovician to Silurian), characterized by thin volcanics and volcaniclastics of andesitic and rhyolitic composition. U-Pb zircon data give Middle Ordovician age (463 Ma – 468 Ma). The third domain, exposed northwest of Veitsch, consists of thick metadacites (Blasseneck Porphyroid, ca. 478 Ma), followed by (siliceous) phyllites which grade into turbiditic metasediments (Sommerauer Formation, Late Ordovician to Devonian?). Clastic sediments of the Stocker and Sommerauer Formations were sourced from northern Gondwana showing a prominent Pan-African detrital zircon peak at ca. 640 Ma. Middle to Upper Ordovician volcanics (ca. 462 Ma – 448 Ma) represent the second source. Tectonic reconstruction leads us to the arrangement of three facies domains. A shallow marine shelf facies is located in the present days southwest. A marginal basin with volcanic islands on a sloping continent, and a deep-water environment containing turbidites are situated further to the northwest. The present arrangement of these facies domains is explained by eo-Alpine and Variscan thrust tectonics.</p> </abstract>ARTICLEtrue biostratigraphy and lithostratigraphy of the Glinzendorf Syncline based on well Gänserndorf UeT3 (Vienna Basin, Austria)<abstract> <title style='display:none'>Abstract</title> <p>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.</p> <p>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.</p> </abstract>ARTICLEtrue Rigelj Formation, a new lithostratigraphic unit of the Lower Permian in the Karavanke Mountains (Slovenia/Austria)<abstract> <title style='display:none'>Abstract</title> <p>The Rigelj Formation is a new lithostratigraphic unit of the Lower Permian Rattendorf Group in the Karavanke Mountains. The Formation is up to 105 m thick and mainly composed of siliciclastic and fossiliferous carbonate sediments that are entirely of shallow-marine setting. Conglomerates are interpreted as shoreface deposits, sandstones as deposits of the upper to lower shoreface, and fossiliferous siltstones as offshore deposits. Fossiliferous limestones were deposited in a shallow, open-marine shelf environment of moderate to low energy (wackestone, floatstone) and strong water turbulence (packstone, rudstone). The siliciclastic and carbonate lithotypes form some well-developed backstepping cycles starting with conglomerates, overlain by sandstones, siltstones and fossiliferous limestones that formed in an open shelf environment without siliciclastic influx. Similar sedimentary cycles are developed in the Grenzland Formation of the Carnic Alps.</p> <p>The fusulinid fauna indicates that the Rigelj Formation ranges in age from the late Asselian to the middle Sakmarian. In the western Karavanke Mountains and near Trögern, the Lower Permian lithostratigraphic succession is very similar to the succession in the Carnic Alps with Tarvis Breccia resting on the Trogkofel Limestone and the Goggau Limestone. Unlike this, in the central part of the Karavanke Mountains (Dovžanova Soteska–Mt. Pleschiwetz/Plešivec area) the Rigelj Formation is erosively overlain by the Tarvis Breccia. The stronger diversification of the sedimentary environments within the Karavanke-Carnic Alps in the Lower Permian after the uniform sedimentation in the Upper Carboniferous can be attributed to block-faulting.</p> </abstract>ARTICLEtrue and geochronological investigations on the individual nappes of the Meran-Mauls nappe stack (Austroalpine unit/South Tyrol, Italy)<abstract> <title style='display:none'>Abstract</title> <p>The Meran-Mauls nappe stack is part of the Austroalpine unit in South Tyrol (Italy). There it holds a special position directly in front of the Southalpine Dolomites indenter and west of the Tauern Window. It is situated in the hanging wall of the Southalpine unit, above a NW dipping segment of the Periadriatic fault system, namely the Meran-Mauls fault. Also all other sides are defined by Oligocene-Miocene strike-slip and normal faults. Based on recent mapping the Meran-Mauls nappe stack consists of three nappes separated by NW to NNW dipping shear zones. The lowermost nappe in the southwest is represented by the Schenna (Scena) unit. It is overlain along the Masul shear zone by a nappe consisting of the Hirzer (Punta Cervina) unit and the Pens (Pennes) unit including Triassic (meta)sediments. Separated by the Fartleis fault the St. Leonhard (San Leonardo) unit forms the uppermost nappe. The aim of this study is to describe the individual units and the separating structural elements more properly, based on new structural, petrological, geothermobarometric and geochronological data and to compare these units to other Austroalpine elements in the vicinity. Sillimanite-bearing paragneiss, minor amphibolite and quartzite as well as a distinct marble layer close to its base characterise the Schenna unit. Further, it contains pegmatite dikes, presumably Permian in age. Amphibolite-facies P-T conditions of c. 0.55 ± 0.15 GPa and 600 ± 100°C are thus correlated with a Permian metamorphic imprint. The Masul shear zone mostly consists of mylonitic paragneiss of the Hirzer unit. It is pre-Alpine in age and probably formed during the Jurassic. For the paragneiss of the Hirzer unit upper greenschist- to amphibolite-facies metamorphic conditions of 0.4-0.50 ± 0.15 GPa and 550 ± 70°C are attributed to the Variscan tectonometamorphic imprint. The whole Pens unit represents a shear zone. Due to the occurrence of Permotriassic (meta)-sediments within this shear zone, it is an Alpine structure, as well as the bordering Fartleis fault. Rb/Sr biotite ages yield sometimes partly reset pre-Alpine age values in the whole Meran-Mauls nappe stack, indicating a pervasive anchizonal to lowermost greenschist-facies metamorphic overprint during the Eoalpine tectonometamorphic event. Tectonostratigraphically the Meran-Mauls nappe stack can be attributed to the Drauzug-Gurktal nappe system. The latter forms the uppermost structural element of the Austroalpine nappe stack and thus only shows a weak Eoalpine metamorphic overprint. With respect to its special lithologic composition the Schenna unit can be correlated with the Tonale unit in the southwest and the Strieden-Komplex in the east.</p> </abstract>ARTICLEtrue tourmaline and its petrogenetic significance from the Maramureș Mountains (East Carpathians, Romania)<abstract> <title style='display:none'>Abstract</title> <p>This study describes mineralogical and crystallochemical characteristics of metamorphic tourmalines from an Alpine shear zone in a Variscan metamorphic rock sequence from the Maramures region in the northern part of the East Carpathians. We use this mineral to unravel aspects of the evolution of the tourmaline bearing host rocks and compare the crystallo-chemical characteristics to other tourmalines from Alps. Petrographic and microstructural observations, as well as electron microprobe analyses on several zoned tourmalines and associated minerals (mica, feldspar) from mylonitic schist of the Rebra terrane (Maramureș Mountains), indicate that the pre-kinematic tourmalines belong to the alkali group (Na dominant), hydroxyl dominated on the crystallographic W-site and can be assigned to the species dravite and schorl. The tourmaline-bearing rocks have a metasedimentary protolith. The analysed porphyroblasts, rotated by simple shear, show corroded rim that are interpreted to have formed due to pressure release. Three main compositional zones were evidenced on a tourmaline porphyroblast: a core zone and two asymmetrically arranged inclusion-poor/free rims, all formed in pre-alpine prograde metamorphic conditions. Based on mineral microstructural relations and geothermobarometry (tourmaline–muscovite, tourmaline–plagioclase geothermometry and phengite geobarometry), the metamorphic peak conditions of the investigated Rebra terrane were evaluated to have been at a temperature of ca. 590 to 620 ± 22 °C and P<sub>min</sub> = 5.5 - 6.0 ± 0.5 kbar. By observing dynamically recrystallized microstructures in quartz and feldspar in the shear zone a temperature of 350 - 400 °C was estimated and the quartz paleopiezometry outlined a differential stress of about 1.5 kbar that implied only minor chemical change in tourmaline outer zone.</p> </abstract>ARTICLEtrue detachment mechanism of the rockslide causing the Chamoli February 7, 2021 debris flow disaster<abstract> <title style='display:none'>Abstract</title> <p>On February 7<sup>th</sup>, 2021, a rockslide of about 20 Mio m³ detached in a height of 5600 m asl. from the northern flank of Mount Ronti (Chamoli district, Uttarakhand state, India), turned into a rock mass fall and produced a debris flow. When the rock mass hit the Ronti Gad valley after a fall height of 1800 m the rock mass mixed with melting dead ice together with snow and ice avalanche material of previous debris flows. The debris flow destroyed hydroelectric infrastructure between 10 - 20 km down the valley killing 204 people either working at or visiting the power plants. By combining remote sensing, structural geology and kinematics/mechanical analysis of the rockslide, we demonstrate that a 600 m wide and almost 800 m long block of quartzite, bordered laterally by two joints and a newly formed tension crack on the top detached from an underlying layer of biotite-rich paragneisses. Assuming full hydrostatic heads in both joints and in the tension crack as well as 75% of the full hydrostatic head in the lower boundary surface between quartzites and paragneisses, the rock block analysis yields a friction angle of 32° for both joints, which is a plausible value of the friction angle of joints in quartzites. The detachment of the block has been the result of the widening of the tension crack on top, of a progressive propagation of the lateral joints together with a catastrophic failure of the detachment plane at the border between quartzites and paragneisses. At the time of the failure, all discontinuities must have been almost completely filled with water raising the question, if the frequency of rockslides in the Himalayas is increasing as temperatures rise and permafrost is thawing due to climate change.</p> </abstract>ARTICLEtrue and C/O-isotopes in lacustrine dolomites reflect variable environmental conditions in the Germanic Basin (Arnstadt Formation, Upper Triassic)<abstract> <title style='display:none'>Abstract</title> <p>The conditions in ancient evaporative environments conducive to authigenic carbonate (especially dolomite [CaMg(CO<sub>3</sub>)<sub>2</sub>]) formation are still insufficiently understood. Insights from microfacies analysis can help to constrain the conditions in these environments. We provide a brief overview of the microfacies association and carbon and oxygen isotope compositions of dolomite beds intercalated in a claystone-rich succession from the Norian Arnstadt Formation in Thuringia and Lower Saxony (Germany) in order to gain further insight into the depositional conditions and processes leading to the formation of authigenic Mg/Ca-carbonates in the Germanic Basin. The studied intervals are ascribed to lacustrine, partially evaporitic conditions, while the sedimentary structures were not obliterated by recrystallization. The microfacies of the dolomites is diverse, showing homogeneous micrite, mudclasts, lamination, and peloidal structures, and reflects a shallow to deeper water (below wave base) and episodically evaporative environment. The dolomites exhibit oxygen isotope values (δ<sup>18</sup>O) in the range from −5.21 to −0.36‰ VPDB and, hence, only represent a weak meteoric influence, suggesting that the authigenic carbonate generally formed under evaporative conditions. Carbon isotope values (δ<sup>13</sup>C) in the range of −4.28 to 1.39‰ VPDB indicate a small contribution of remineralized organic carbon, mainly in sediments that were presumably deposited in deeper water or under brackish conditions. Sedimentary structures, such as lamination with graded silt layers, reworked mudclasts embedded in a fine dolomicrite matrix, and peloids showing plastic deformation, indicate that the sediment was still unlithified. These observations would be consistent with an authigenic formation of Mg/Ca-carbonates directly from the lake water, and their deposition under variable conditions in a large playa-lake/perennial lake system.</p> </abstract>ARTICLEtrue