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

LANNUTTI ESTEBAN; BOTTEGAL ESTEFANIA; SAITO KAZUYUKI ; DARÍO TROMBOTTO LIAUDAT

Sapporo

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

 The distribution ofAndean mountain permafrost and its response to climate warming has taken greatimportance in areas of mountain environments due to the potential ofunderground ice (ice-rich soils) such as storage of freshwater reservoirs, especiallyin regions where this resource is scarce as it is in semi-desert climates likein the Central Andes. Rock glaciers havebeen recognized by their hydrological importance and represent the most important geoforms of the Andean periglacialenvironment. They are considered as the main geomorphological expression ofmountain permafrost (Monnier & Kinnard 2013). Cryodynamicsin Morenas Coloradas rock glacier in the Central Andes was measured fromOctober 2013 until February 2016. To estimatethe glacier crydynamic activity a GPS network of 20 geodesic measurement pointswas installed on the rock glacier surface. During the study period, 5 sessions with 48 hours of continuous duration oneach 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 tocalculate the coordinates and velocities of the points using a dual-frequencydifferential processing (L1-L2) and IGS stations (International GNSS Service)as reference. MorenasColoradas denote signs of activity through fronts with slopes >35 ° and a classic "wrinkle" morphology in the form of surface arcsindicating their flow movements (Trombotto et al.1999). The results show an importantcryodynamics activity. Displacements goes from few centimeters to couple ofmeters. Most of the measured point have a South- East direction. Those that arein the zone of lower altitude show the greater displacements therefore thegreater velocity, due to a loss of ice volume. At a higher altitude, thermokarstare found which reveal a degradation of the permafrost at that site where highvelocities predominate the zone.  The movement direction measured withthe GPS is coincident with the direction of flow observed in that ?wrinkle?morphology mentioned by Trombotto et al. (1999). Some of themeasured points show very little or almost no movement indicatinginactivity of these lobes. It can be affirmed that those points belong toinactive or fossils lobes within the Morenas Coloradas rocks glacier. Inaddition, the morphology observed in these lobes are mostly structures ofcollapse and a chaotic surface with depressions. Stunted vegetation is alsopresent in these kind of lobes. Unlike other rock glaciers, Morenascoloradas presents a complex morphology formed by several lobes withdifferentiated cryodynamic activities.