Our new dataset from the Rivoli-Avigliana end-moraine system, the westernmost amphitheatre of the Italian Alps, provides an important step towards understanding foreland-reaching glaciations before and during the Last Glacial Maximum (LGM) in the Western Alps. 10Be data from six boulders in pre-LGM deposits gave ages between 26.82.1 and 41.21.9 ka. Based on morphological and pedological data, we interpret the oldest age as a minimum age for the glacier advance(s). 10Be results suggest that the LGM occurred in two major steps. During the first at 24.01.5 ka, several ridges were constructed demonstrating oscillation of the Dora Riparia glacier snout at the maximum position. Our data demonstrate a significantly larger LGM extent in the Rivoli- Avigliana amphitheatre than shown on previous maps. The maximum advance was followed by a short re-advance of the glacier at 19.60.9 ka, as recorded by 10Be ages from boulders in lateral positions along the lower Susa Valley. The maximum ice surface during the LGM was at 1000-920m a.s.l. in the final reach of the valley (560- 620m of elevation above the alluvial plain) and at 620-340m a.s.l. at the continuous moraines in the amphitheatre.
New geomorphological and chronological constraints for glacial deposits in the Rivoli-Avigliana end-moraine system and the lower Susa Valley (Western Alps, NW Italy)
Lucchesi S;Fioraso G;Monegato G;
2018
Abstract
Our new dataset from the Rivoli-Avigliana end-moraine system, the westernmost amphitheatre of the Italian Alps, provides an important step towards understanding foreland-reaching glaciations before and during the Last Glacial Maximum (LGM) in the Western Alps. 10Be data from six boulders in pre-LGM deposits gave ages between 26.82.1 and 41.21.9 ka. Based on morphological and pedological data, we interpret the oldest age as a minimum age for the glacier advance(s). 10Be results suggest that the LGM occurred in two major steps. During the first at 24.01.5 ka, several ridges were constructed demonstrating oscillation of the Dora Riparia glacier snout at the maximum position. Our data demonstrate a significantly larger LGM extent in the Rivoli- Avigliana amphitheatre than shown on previous maps. The maximum advance was followed by a short re-advance of the glacier at 19.60.9 ka, as recorded by 10Be ages from boulders in lateral positions along the lower Susa Valley. The maximum ice surface during the LGM was at 1000-920m a.s.l. in the final reach of the valley (560- 620m of elevation above the alluvial plain) and at 620-340m a.s.l. at the continuous moraines in the amphitheatre.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
