Reconsidering the current stratigraphy of the Alpine Lateglacial

The sedimentary and morphological evidence for Lateglacial glacier fluctuations in the Lienz area provides a strong case against the currently used pentapartite stratigraphic subdivision of the Alpine Lateglacial (ALG; c. 19–11.7 ka) i.e. the timespan between the Würmian Pleniglacial (= Alpine Last Glacial Maximum; AlpLGM) and the beginning of the Holocene. The results of comprehensive geological mapping (including the detection of mass movements) supported by geochronological data and pollen analysis revealed that the ALG- record of the Schobergruppe mountains and the Lienz Dolomites can be subdivided into four unconformity-bounded (allostratgraphic) units which are linked to three climatostratigraphically-defined phases of glacier activity. Delta deposits and till of local glaciers document the phase of ice-decay after the AlpLGM. Between this period and the Bølling/Allerød (B/A) interstadial only one glacier stabilisation with massive end moraines, correlated with the Gschnitz stadial, is evident. Multiple end moraines prove the presence of very active glacier tongues during the Younger Dryas aged Egesen stadial. The 10Be exposure dating of an end moraine, previously attributed to the Daun stadial (pre-B/A interstadial) based on ΔELA values, provided an age of 12.8 ± 0.6 ka indicating it is of Younger Dryas age. This case highlights the pitfalls of the commonly used ΔELA-based stratigraphic ALG subdivision and the subsequent derivation of palaeoclimatic implications. ΔELAs are still considered as a useful tool for correlation on the local scale e.g. in one mountain group with a quite comparable topography and lithology and taking into account the limitations, especially the impact of debris cover. However, our results show that a stratigraphic correlation across the whole Alpine chain via ΔELAs is not a successful approach potentially leading to bias and, eventually, to circular arguments.researc

Zusammenstellung ausgewählter Archivunterlagen der Geologischen Bundesanstalt

GEOFAST steht als Abkürzung für Geologische Karten von Österreich die durch Zusammenstellung ausgewählter Archivunterlagen der Geologischen Bundesanstalt im Maßstab 1:50.000 kompiliert wurden. Hierfür werden die Archivbestände der Geologischen Bundesanstalt für den Raum des Kartenblattes 53 Amstetten durchforstet, zusammen mit Regionalexperten wissenschaftlich fundiert ausgewählt und anschließend die besten Inhalte zu einer Karte kompiliert, digitalisiert und in moderner Form auf die aktuelle Topografie angepasst inklusive der Verwendung von hoch aufgelösten digitalen Geländemodellen (Laserscan). Diskontinuitäten zwischen den verwendeten Kartenunterlagen verschiedener Autoren werden bewusst beibehalten und können sich als Sprünge in den Konturlinien äußern. Geologische Inhalte werden in die aktuellen stratigrafischen und tektonischen Modelle überführt. Aufgrund der Übertragung der geologischen Inhalte von Karten mit veralteter Topografie und größeren Maßstäben in die aktuelle topografische Grundlage sind Lageungenauigkeiten vorhanden.GEOFAST stands for geological maps of Austria that were compiled by a set of selected maps form the archives of the Geological Survey of Austria on a scale of 1: 50,000. For this purpose, archives of the Geological Survey of Austria for the map sheet 53 Amstetten are scanned and the best available maps selected in cooperation with regional experts, resulting in a compiled and digitized map additionally adapted to the current topography, including the use of high-resolution digital terrain models (laser scan). Discontinuities between the map documents used by different authors are deliberately retained and can manifest themselves as jumps in the contour lines. Geological content is transferred to the current stratigraphic and tectonic models. Due to the transfer of the geological content of maps with outdated topography and larger scales to the current topographical basis, there are positional inaccuracies