MONITORING MORENAS COLORADAS ROCK GLACIER CRYODYNAMICS IN THE CENTRAL ANDES, MENDOZA, ARGENTINA

DARIO TROMBOTTO; BOTTEGAL, ESTEFANÍA; KAZUYUKI SAITO; LANNUTTI, ESTEBAN

Sapporo

Conferencia; The 2nd Asian Conference on Permafrost (ACOP2017); 2017

International Permafrost Association

The distribution of Andean mountain permafrost and its response to climate warming has taken great importance in areas of mountain environments due to the potential of underground ice (ice-rich soils) such as storage of freshwater reservoirs, especially in regions where this resource is scarce as it is in semi-desert climates like in the Central Andes. Rock glaciers have been recognized by their hydrological importance and represent the most important geoforms of the Andean periglacial environment. They are considered as the main geomorphological expression of mountain permafrost (Monnier & Kinnard 2013). Cryodynamics in Morenas Coloradas rock glacier in the Central Andes was measured from October 2013 until February 2016. To estimate the glacier crydynamic activity a GPS network of 20 geodesic measurement points was installed on the rock glacier surface. During the study period, 5 sessions with 48 hours of continuous duration on each point were measured to eliminate noises of seasonal and daily cycles (Blewitt & Lavallée 2002). Bernese scientific software version 5.0 (Dach et al. 2007) was used to calculate the coordinates and velocities of the points using a dual-frequency differential processing (L1-L2) and IGS stations (International GNSS Service) as reference. Morenas Coloradas denote signs of activity through fronts with slopes > 35 ° and a classic "wrinkle" morphology in the form of surface arcs indicating their flow movements (Trombotto et al. 1999). The results show an important cryodynamics activity. Displacements goes from few centimeters to couple of meters. Most of the measured point have a South- East direction. Those that are in the zone of lower altitude show the greater displacements therefore the greater velocity, due to a loss of ice volume. At a higher altitude, thermokarst are found which reveal a degradation of the permafrost at that site where high velocities predominate the zone. The movement direction measured with the GPS is coincident with the direction of flow observed in that ?wrinkle? morphology mentioned by Trombotto et al. (1999). Some of the measured points show very little or almost no movement indicating inactivity of these lobes. It can be affirmed that those points belong to inactive or fossils lobes within the Morenas Coloradas rocks glacier. In addition, the morphology observed in these lobes are mostly structures of collapse and a chaotic surface with depressions. Stunted vegetation is also present in these kind of lobes. Unlike other rock glaciers, Morenas coloradas presents a complex morphology formed by several lobes with differentiated cryodynamic activities.