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Quartär – Internationales Jahrbuch zur Erforschung des Eiszeitalters und der Steinzeit, Bd. 55 (2008): Quartär. Internationales Jahrbuch zur Eiszeitalter- und Steinzeitforschung

Kettle holes are common ice decay features in formerly glaciated areas. They are highly variable in size and geometry and may form in a variety of glacial and glaciofluvial landforms. Kettle holes are either dry or exist as wetlands or lakes, only rarely transforming into kettle-hole mires. This study investigates Late Pleistocene kettles in the area of the LGM Salzach Glacier Lobe in the North Alpine Foreland. Kettles are here specifically well preserved and concentrate along the former glacier lobe terminus, where they could develop within large elevated areas protected from pro and postglacial sediment redistribution also showing minor anthropogenic overprint. Highest kettle concentrations were observed within a narrow swath along the distal lobe dominated by terminal moraines, ice wastage and outwash deposits, whereas they are almost absent in the centre of the former glacier lobe. Based on a new dataset on regional kettle distribution and a study of comparable wetland environments, we show that kettle lake formation is a specific but rare phenomenon, which is closely related to the preceding dynamics at the glacier lobe and the glacial depositional environment. By applying geophysical surveys (electrical resistivity tomography, ground-penetrating radar), topographic as well as stratigraphic investigations (DEM analysis, core-drilling and radiocarbon dating), we explore the postglacial evolution of the Jackenmoos kettle and propose a modified model of peat formation in kettle-hole mires, mainly as a function of the centripetal growth of a floating mat covering a central subsurface water body. (VLID)2496995

The start of the Upper Wurmian in the Alps was marked by massive fluvioglacial aggradation prior to the arrival of the Central Alpine glaciers. In 1984, the Subcommission on European Quaternary Stratigraphy defined the clay pit of Baumkirchen (in the foreland of the Inn Valley, Austria) as the stratotype for the Middle to Upper Wurmian boundary in the Alps. Key for the selection of this site was its radiocarbon chronology, which still ranks among the most important datasets of this time interval in the Alps. In this study we re-sampled all available original plant specimens and established an accelerator mass spectrometry chronology which supersedes the published 40-year-old chronology. The new data show a much smaller scatter and yielded slightly older conventional radiocarbon dates clustering at ca. 31 C-14 ka BP. When calibrated using INTCAL13 the new data suggest that the sampled interval of 653-681 m in the clay pit was deposited 34-36 cal ka BP. Using two new radiocarbon dates of bone fragments found in the fluvioglacial gravel above the banded clays allows us to constrain the timing of the marked change from lacustrine to fluvioglacial sedimentation to ca. 32-33 cal ka BP, which suggests a possible link to the Heinrich 3 event in the North Atlantic.