Last Glacial Maximum and the Gschnitz stadial in the Maritime Alps according to ¹⁰Be cosmogenic dating

Abstract

Two glacial deposits in the Gesso valley (Maritime, Alps) have been 10Be‐dated at 20 140±1080 (weighted mean±SD) and 16 590±970 years, respectively, thus constraining the Last Glacial Maximum (LGM) and Gschnitz stadials in the southwestern part of the Alps. The LGM age is chronologically coherent with MIS 2 and synchronous with most other LGM moraines in the Alps. The Gschnitz stadial also appears to be in agreement with the ages obtained from other Alpine sites and with Heinrich Event I. This suggests that the Alpine glaciers reacted simultaneously and essentially synchronously with the climate change associated with Heinrich Event 1. The Equilibrium Line Altitudes (ELAs) of the LGM and Gschnitz reconstructed palaeoglaciers are 1850 and 1910 m a.s.l., respectively. The ELA comparison across the Alps indicates that the palaeoclimate of the Maritime Alps during the LGM was rather different from that of other Alpine sectors. However, the similar Gschnitz ELA value between the Gesso valley and other sites across the mountain chain indicates that Alpine glaciers responded with the same intensity to the climate change associated with Heinrich Event I. Overall, these results suggest that the interaction between the atmospheric circulation of air masses and local Alpine orography was more complex than has previously been argued.

Thermomechanical stress–strain numerical modelling of deglaciation since the Last Glacial Maximum in the Adamello Group (Rhaetian Alps, Italy)

“…The first clear Late Glacial re-advance of Alpine glaciers occurred during the Gschnitz stadial (Castiglioni, 1961) and has been documented in several other areas of the Alps Böhlert et al, 2011;Federici et al, 2012). Moraines and glacial deposits of this phase in the Valcamonica and in the Adamello Group were deposited on previously deglaciated areas and on late Pleistocene glacial drift .…”

<sup>10</sup>Be depth profiles in glacial sediments on the Swiss Plateau: deposition age, denudation and (pseudo-) inheritance

“…The minimum deposition ages T eff of 14, 11 and 16 kyr for Deisswil, Steinhof and Niederbuchsiten, respectively, do not provide useful age constraints and only point to high denudation. They do not even exceed the age of the Late Glacial readvances of the Gschnitz Stade in the Alps ∼ 16 ka (IvyOchs et al, 2006a;Reitner, 2007;Federici et al, 2012). It is important to emphasize that the ages in this study obtained from the Monte Carlo calculations should not be overinterpreted either: The age ranges are extremely large and, more importantly, all profiles have reached equilibrium.…”

“…Although mostly based on field work in the Bavarian and Austrian Alps, Penck and Brückner (1909) also applied their scheme to Switzerland. Apart from minor modifications (Eberl, 1930;Beck, 1933), the assumption that there were four glaciations in the Alps did not undergo big changes for decades. In the early 1980s, research based on palynology (Welten, 1982(Welten, , 1988 and sedimentology (Schlüchter and Wolfarth-Meyer, 1986;Schlüchter, 1988Schlüchter, , 1989b led to a turnover of the four classical Quaternary ice ages.…”

Quaternary glaciation in the Mediterranean mountains: a new synthesis

“…There have been numerous studies in the last decade or so in the western Balkans, but large areas remain unstudied, including most of Bosnia and parts of Greece. In Italy, only a few areas have seen both mapping and dating applied to the glacial successions (Giraudi & Frezzotti 1997;Kotarba et al 2001;Federici et al 2008Federici et al , 2012Federici et al , 2016Giraudi et al 2011;Giraudi Giraudi & Giaccio 2015). In Morocco, the mapping and advanced phases are only just beginning and here too this work is restricted to a relatively small area around the SW High Atlas.…”

“…Recent cosmogenic exposure dating by Federici et al (2008Federici et al ( , 2012 has helped constrain the timings of advances, revealing a classic Alpine succession of LGM, Gschnitz (equivalent in time to Heinrich Event I) and Egesen (Younger Dryas) moraines. This work is further refined in this volume by Federici et al (2016), who present more ages from moraines to reinforce the view that the classic Alpine succession is evident in the Maritime Alps.…”