An Outline of the Quaternary Stratigraphy of Austria

Es wird ein Überblick über die in Österreich verwendete Quartär-Stratigraphie gegeben. Die stratigraphische Gliederung der kartierbaren Sedimenteinheiten basiert teilweise auf Kriterien der Lithostratigraphie (lithologischer Eigenschaften) und jenen der Allostratigraphie (z.B. Diskonitinuitäten). Für das Altpleistozän (2.58–0.78 Ma) fehlen bis jetzt Spuren einer Vergletscherung. Die wenigen und isolierten Sedimentvorkommen belegen fluviatile Akkumulation und Lössablagerung in der Umgebung der Flüsse. Paläomagnetisch korrelierte Löss-Paläoboden – Sequenzen wie das Profil Stranzendorf mit der Gauss/Matuyama – Grenze bzw. Neogen/Quartär – Grenze dokumentieren in Übereinstimmung mit den globalen δ18O Werten etwas wärmere Bedingungen als im Mittelpleistozän (0.78–0.13 Ma). Vier Großvergletscherungen (Günz, Mindel, Riß und Würm) sind für Mittelpleistozän und Jungpleistozän belegt. Diese sind mit Sedimenten aus der Vorstoßphase überlagert von Grundmoräne, Endmoränen im Alpenvorland und damit verknüpfte Terrassenschüttungen sowie Lössakkumulation dokumentiert. Daraus ist die klimagesteuerte Sedimentation im Zusammenhang mit dem Vorstoß der Gletscher, der Ausbreitung des Permafrostes und der Frostschuttbildung bis ins Vorland erkennbar. Die jüngsten Großvergletscherungen Riß und Würm werden aufgrund geochronologischer Daten mit den Marinen Isotopenstufen (MIS) 6 und 2 korreliert. Für Günz und Mindel scheint eine Gleichzeitigkeit mit den Phasen massiver globaler Klimaverschlechterung während MIS 16 und MIS 12 plausibel. Dokumente für die schwächeren Glaziale wurden bisher nur in Lössprofilen (z.B. Krems Schießstätte) gefunden

Distribution, geometry, age and origin of overdeepened valleys and basins in the Alps and their foreland

Overdeepened valleys and basins are commonly found below the present landscape surface in areas that were affected by Quaternary glaciations. Overdeepened troughs and their sedimentary fillings are important in applied geology, for example, for geotechnics of deep foundations and tunnelling, groundwater resource management, and radioactive waste disposal. This publication is an overview of the areal distribution and the geometry of overdeepened troughs in the Alps and their foreland, and summarises the present knowledge of the age and potential processes that may have caused deep erosion. It is shown that overdeepened features within the Alps concur mainly with tectonic structures and/or weak lithologies as well as with Pleistocene ice confluence and partly also diffluence situations. In the foreland, overdeepening is found as elongated buried valleys, mainly oriented in the direction of former ice flow, and glacially scoured basins in the ablation area of glaciers. Some buried deeply incised valleys were generated by fluvial down-cutting during the Messinian crisis but this mechanism of formation applies only for the southern side of the Alps. Lithostratigraphic records and dating evidence reveal that overdeepened valleys were repeatedly occupied and excavated by glaciers during past glaciations. However, the age of the original formation of (non-Messinian) overdeepened structures remains unknown. The mechanisms causing overdeepening also remain unidentified and it can only be speculated that pressurised meltwater played an important role in this contex

Unravelling the shape and stratigraphy of a glacially-overdeepened valley with reflection seismic: the Lienz Basin (Austria)

We reveal the subsurface bedrock topography and sedimentary succession of one of the deepest glacially-formed basins in the Eastern Alps: the Lienz Basin in the Upper Drau Valley (Tyrol), by means of seismic reflection. A dense source-receiver spacing, supplied by autonomous receivers, and a prestack depth-migration processing scheme were essential to distinguish the various deposits in fine detail, such as slumping, fan delta deposits, and a modified monocline on the basin flank. These details support our interpretation of the seismic stratigraphy that consists of, e.g., subglacial till of last glacial maximum (LGM) age and possibly older, laminated basin fines, and gravel/coarse sand. The maximum depth of the basin is 622 m, at the junction of two major basement faults that are not clearly visible in the seismic reflections. We regard the overdeepening in this longitudinal valley as the result of glacier confluence during the LGM. Subglacial meltwaters utilized the higher erodibility of faulted rocks, as indicated by channel structures. The adverse slope (2.6%) along the valley axis exceeds the gradient ice-surface slope (0.4–0.5%) during the LGM by more than fivefold. We thus suggest this feature is a product of a pre-LGM phase, since adverse slopes greater than ~ 1.2 times the ice surface slope promote the freezing of water in subglacial channels and prevent efficient water flushing of sediments. Integrating other studies allows us to estimate the local overdeepening of the Lienz Basin and that of the whole Upper Drau Valley to be 146 m and 530 m, respectively. At the beginning of lacustrine sedimentation, we estimate the paleo-water depth to be at least 216 m

Abstracts from the 20th International Symposium on Signal Transduction at the Blood-Brain Barriers

https://deepblue.lib.umich.edu/bitstream/2027.42/138963/1/12987_2017_Article_71.pd

Microbial fabric formation in spring mounds ("microbialites") of alkaline salt lakes in the Badain Jaran Sand Sea, PR China

The large sandy desert of Badnin Jaran Shamo, Inner Mongolia, has several salt lakes located among megadunes with crests as high as 400 m. Most of the lakes are hypo- to hypersaline and alkaline, with pH values between 8.5 and 10. Because of their reef-like aragonitie pinnacles rising from the lake floor, Lake Nuoertu and Lake Huhejaran haue been investigated in detail. The porous limes tones of the tufa pinnacles ("spring mounds'') result {rom a hydrochemieally forced, exopolymer-mediated calcification of cyanobacteria- dominated mierobial mats at sublacustrine springs. The development oftheir enigmatie fabries is documented for the first time. Siekle-cell-like and bubbleshaped fabries reflect successive mineralization during degradation, shrinkage of the organie mucus, and gas formation by bacteria. Fossil analogues are known from the Pleistocene and Miocene (Ries-crater lake), but older non-marine, Phanerozoie examples are expected. 1b the extent that these textures are associated exclusively with alkaline environments, they can be used to test the hypothesis of an alkali ne ocean early in Earth history

Reconstructing basal ice flow patterns of the Last Glacial Maximum Rhine glacier (northern Alpine foreland) based on streamlined subglacial landforms

Based on high-resolution (sub)glacial geomorphological mapping, we present a first digital inventory of streamlined bedforms within the footprint of a Last Glacial Maximum (LGM) Alpine piedmont glacier. A total of 2460 drumlins were mapped across the Rhine glacier foreland. Glacial lineations and one field of subglacial ribs (ribbed/Rogen moraines) - the first record of this type of subglacial landform on the Alpine foreland-were identified. Two flowsets, associated with (i) the Rhine glacier's LGM maximum advance (Schaffhausen stadial) and (ii) a late LGM readvance (Stein am Rhein stadial), are differentiated. The vast majority of streamlined bedforms occur in fields aligned in a 16- to 30-km-wide swath upstream of the Stein am Rhein frontal moraines. Orientation and elongation of drumlins and glacial lineations set the basis for the reconstruction of paleo-ice flow. Basal flow paths of the LGM maximum advance are visually interpreted and restricted to the zone proximal to the former ice front. The flow field reconstructed for the late LGM glacier readvance (Stein am Rhein stadial) extends tens of kilometres upstream and is modelled implementing a recently published kriging routine. The derived basal flow patterns paired with information on ice surface levels from lateral and frontal moraines and combined with relative ice velocity differences inferred from spatial changes in bedform elongation reveal detailed insights on ice flow geometries, particularly during the glacier readvance. Reconstructed flowlines highlight basal flow under shallow ice that is strongly controlled by local topography evidenced by diverging around basal bumps and converging in (narrow) valley sections and troughs, where basal flow velocities, steered by topography, are high. Gained paleo-ice basal flow patterns offer new insights on landscape evolution of the northern Alpine foreland and provide evidence-based flow data to validate future physical modelling results.ISSN:0197-9337ISSN:1096-983

Geodata of raw material districts and geochemical analyses of Austrian loess and loess loam deposits

Die in dieser Datenpublikation veröffentlichten Daten umfassen ausgewählte Datensätze, die im Zuge des Projektes „Baurohstoffvorsorge Lösse und Lösslehme“ im Rahmen der Initiative GBA-Forschungspartnerschaften Mineralrohstoffe (MRI) generiert wurden. Ziel dieses Projektes war es, unterschiedliche Analysendatenbestände zusammenzuführen, zu vereinheitlichen, unter Zuhilfenahme statistischer Methoden gemeinsam auszuwerten und auf Grundlage dieser Auswertung eine Gliederung der Löss- und Lösslehmvorkommen im ober- und niederösterreichischen Alpenvorland und im Wiener Becken nach rohstoffgeologischen Gesichtspunkten aufzustellen. So konnten 24 räumlich und genetisch-stratigraphisch zusammengehörende Löss- bzw. Lösslehm-Rohstoffbezirke ausgewiesen und als Polygone für die Implementierung in das webbasierte „Interaktive RohstoffinformationsSystem“ IRIS‐Baurohstoffe abgegrenzt werden. Die vorliegende Datenpublikation beinhaltet einerseits die 24 Löss- bzw. Lösslehm-Rohstoffbezirke als GIS-Datensatz und andererseits geochemische Analysen von 58 Löss- bzw. Lösslehmproben, die im Zuge des Projektes neu analysiert wurden.The data published in this data publication include selected data sets generated as part of the project “Baurohstoffvorsorge Lösse und Lösslehme” within the framework of the Austrian Minerals Resources Research Partnership (Forschungspartnerschaften Mineralrohstoffe - MRI). The aim of this project was to combine and standardize different analytical data sets, to evaluate them together with the aid of statistical methods, and to establish a classification of the loess and loess loam deposits in the Alpine Foreland areas of Upper and Lower Austria and in the Vienna Basin regarding raw material geological aspects. Thus, 24 spatially, respectively genetically-stratigraphically related loess or loess loam raw material districts could be defined and delineated as polygons for implementation in the web-based Austrian Interactive Raw Materials Information System IRIS-Online. This data publication contains, on the one hand, the 24 loess or loess loam raw material districts as a GIS data set and, on the other hand, geochemical analyses of 58 loess or loess loam samples that were newly analyzed in the course of the project