GLACIAL AND PROGLACIAL DEPOSITS OF THE RESIA VALLEY (NE ITALY): NEW INSIGHTS ON THE ONSET AND DECAY OF THE LAST ALPINE GLACIAL MAXIMUM IN THE JULIAN ALPS

Abstract

The Resia Valley is located in the south-eastern sector of the Alps, where small glacial remnants are still preserved despite the average low-elevation of the reliefs. The abundance of glacigenic deposits related to the Last Glacial Maximum allowed to discuss and reconstruct the onset and decay of the glaciation. The initial glacier expansion from the Canin-Toudule and the Barman cirques led to the infilling of the former valley with fluvioglacial and glaciolacustrine successions. Then, the spread of the Resia Glacier during the LGM climax covered and over-consolidated these units. On the valley flanks, the interaction of the base of the trunk glacier with the sharp preglacial topography caused the formation of subglacial deposits containing large-size sub-angular boulders and glaciolacustrine fines. During the LGM the Resia Glacier reached the maximum thickness of about 550 m, and was tributary of the Fella Glacier at Resiutta. During the Late Glacial, two main stadial phases are characterised by frontal moraines and ice-dammed deposits. In the first, glacier streams flowed down only from the Resartico and Barman valleys, damming the trunk valley; this caused the formation of lakes and the aggradation of the outwash deposits related to the glaciers located in the upper valley. In the second stadial phase, glaciers were confined in highelevation accumulation areas. Nevertheless, the Barman and Canin-Toudule ice streams reached the base of the slope, due to the peculiar climatological setting. In fact, the accumulation area is in one of the highest precipitation rate sector of the Alps (present MAP > 3000 mm). These climatological characteristics allow the preservation of very small glaciers, glacierets and firn-patches at about 2300 m a.s.l. even under the present, warmer climate.