Paraglacial geomorphology associated with slope instability in the North Branch of the Argentino Lake, Argentinean Patagonia

Abstract

The worldwide retreat and thinning of glaciers in recent decades have a direct impact on the stability of the slopes. The Upsala glacier basin and the glaciers of the North Branch of Argentino Lake have suffered a marked retreat, generating valleys with steep slopes and covered with unstable moraine deposits. Therefore, the slopes are strongly destabilized, favoring the generation of paraglacial geomorphological processes. The main goal of this study is to identify and analyze the paraglacial geomorphology associated with instability processes. We analysis the area through the combination of morphometric parameters and intervening factors that condition and trigger these processes by satellite images. The results show that paraglacial geomorphology is influenced by the combination of: (i) terrain morphometric parameters as, among others, terrain elevations exceeding 700 m ASL, average slopes with a range between 25º-45º, east-northwest slopes aspects with greater insolation, concave curvature of the terrain and slight to moderate roughness (0.40-0.65); (ii) conditioning factors, moraine material deposited by glaciers, weathered rock outcrops and vegetation cover; (iii) triggering factors, groundwater infiltration by proglacial lagoons and surface infiltration by rainfall, thaw and runoff, variation of air and soil temperatures and variation of lake level. In conclusion, the slopes with the greatest paraglacial geomorphological processes resulting from mass removal processes are those in direct contact with the Upsala, Bertacchi and Cono glaciers, the western slope of the Upsala channel and some areas of the Moyano and Norte valleys. The area is characterized by a combination of glacial and paraglacial environments, each being an integral part of the evolution of the environment.