Evidence of a two-fold glacial advance during the last glacial maximum in the Tagliamento end moraine system (eastern Alps)

Abstract

The glacial history of the Tagliamento morainic amphitheater (southeastern Alpine foreland, Italy) during the last glacial maximum (LGM) has been reconstructed by means of a geological survey and drillings, radiocarbon dating and pollen analysis in the amphitheater and in the sandur. Two phases of glacial culmination, separated by a distinct recession, are responsible for glacial landforms and related sediments in the outer part of the amphitheater. The age of the younger advance fits the chronology of the culmination of the last glaciation in the Alps, well established between 24 and 21 cal ka BP (20 to 17.5 (14)C ka BP), whereas the first pulse between 26.5 and 23 cal ka BP (22 to 21 (14C) ka BP), previously undated, was usually related to older (pre-LGM) glaciations by previous authors. Here, the first pulse is the most extensive LGM culmination, but is often buried by the subsequent pulse. The onset and final recession of the late Wurm Alpine glaciation in the Tagliamento amphitheater are synchronous with the established global glacial maximum between 30 and 19 cal ka BP. The two-fold LGM glacial oscillation is interpreted as a millennial-scale modulation within the late Warm glaciation, caused by oscillations in inputs of southerly atmospheric airflows related to Dansgaard-Oeschger cycles. Phases of enhanced southerly circulation promoted increased rainfall and ice accumulation in the southern Alps. (c) 2007 University of Washington. All rights reserved

New chronological and stratigraphical data on the Ivrea amphitheatre (Piedmont, NW Italy)

“…Otherwise, the Piverone Af has to be correlated to either a stade of retreat of a penultimate episode, or it has to be considered as the maximum expansion stade of the last glacial episode. In this third case, Piverone Af and Ivrea Af could form a complex similar to the Maximalständ and Hochständ of LGM end moraines observed in the Austrian Alps by van Husen (1997) and to the twofold LGM glacial advance in the Tagliamento amphiteatre (Monegato et al, 2007).…”

“…The data from Wangen indicate that the initial moraine abandonment was underway by 22.1-19.5 ka based on 10 Be (Ivy- Ochs et al, 2006b). Good correlation can be found also with the Remanzacco subsynthem recessional moraines in the Tagliamento Amphiteatre in eastern Italian Alps, dated between 21 and 18.8 cal ka 14 C (Monegato et al, 2007).…”

Glacier variations in the European Alps at the end of the last glaciation

“…The moraines formed during the last glaciation are distinguished from older morphologically less distinct outboard moraines attributed to penultimate glacier expansions during MIS 6 or 8 (Graf, 2009;Keller and Krayss, 2010;Preusser et al, 2011;Fiebig et al, 2011;Gianotti et al, 2015). Records from sites on both the northern and southern side of the Alps suggest advance of glaciers beyond the Alpine front at around 30 ka ago (Keller and Krayss, 2005;Monegato et al, 2007;Scapozza et al, 2015). Ehlers and Gibbard (2004) During the Last Glacial Maximum in the European Alps (late Würm) local ice caps and extensive ice fields in the high Alps fed huge outlet glaciers that occupied the main valleys, for example, the Rhone, Reuss, Rhine, Inn, and Salzach in the northern sector and the Tagliamento, Piave, Sarca, Ticino, Dora Baltea, and Dora Riparia along the southern side ( Figs.…”

“…Data from several of the Italian amphitheatres suggest that LGM glaciers were at their most advanced position of the last glacial cycle between 27 and 21 ka cal BP (Monegato et al, 2007;Ravazzi et al, 2012 and references therein). Based on lithostratigraphy and pollen study underpinned by 14 C dating, a two-phase LGM maximum extent has been recognized at the Tagliamento glacier amphitheatre (Fig.…”

Evolution of a karst polje influenced by glaciation: The Gomance piedmont polje (northern Dinaric Alps)

“…The two main development phases of the Gomance polje can be potentially placed in the dynamics of the glacier fronts, similar to those recognised in the nearby Alps (Monegato et al, 2007;Luetscher et al, 2015), even if a better chronology is needed for this comparison. The dated Bos primigenius scapula found in the outwash deposits of quarry P4 yielded 17.719.7…”