Surface velocity fields of active rock glaciers and ice-debris complexes in the Central Andes of Argentina

Rock glaciers and transitional ice-debris complexes predominate the Central Andean landform assemblage, yet regional studies on their state of activity and their kinematics remain sparse. Here we utilize the national glacier inventory of Argentina to quantify surface velocity fields of 244 rock glaciers and 51 ice-debris complexes, located in the Cordón del Plata range, Argentina. Applying a feature-tracking approach to repeated RapidEye satellite imagery acquired between 2010 and 2017/18, we find mean displacement rates between 0.37 and 2.61 m year−1 for 149 landforms, while for the remaining 146 features, surface movement remains below our level of detection. We compare our satellite-derived velocity fields with ground-truth data from two local field sites and find closely matching results in magnitude and spatial distribution. With average displacement of one-third of the active rock glaciers and ice-debris complexes exceeding 1 m year−1, the region hosts an exceptional number of fast-flowing periglacial landforms, compared to other mountain belts. Using a random forest model, we test the predictive power of 25 morphometric and topoclimatic candidate predictors for modelling the state of activity of rock glaciers and ice-debris complexes on two different scales. For entire landforms and individual landform segments, constructed along displacement centrelines, we can predict the state of activity with overall accuracies of 70.08% (mean AUROC = 0.785) and 74.86% (mean AUROC = 0.753), respectively. While topoclimatic parameters such as solar radiation and elevation are most important for entire landforms, geometric parameters become more important at the scale of landform segments. Despite tentative correlations between local slope and surface kinematics, our results point to factors integrating slope and distance to the source to govern local deformation. We conclude that feature tracking in optical imagery is feasible for regional studies in remote regions and provides valuable insight into the current state of the Andean cryosphere.Fil: Blöthe, Jan Henrik. Universitat Bonn; AlemaniaFil: Halla, Christian. Universitat Bonn; AlemaniaFil: Schwalbe, Ellen. Technische Universität Dresden; AlemaniaFil: Bottegal, Estefania Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Trombotto, Dario Tomas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Schrott, Lothar. Universitat Bonn; Alemani

Factors controlling the water quality of rock glacier springs in European and American mountain ranges

Rock glaciers (RGs) provide significant water resources in mountain areas under climate change. Recent research has highlighted high concentrations of solutes including trace elements in RG-fed waters, with negative implications on water quality. Yet, sparse studies from a few locations hinder conclusions about the main drivers of solute export from RGs. Here, in an unprecedented effort, we collected published and unpublished data on rock glacier hydrochemistry around the globe. We considered 201 RG springs from mountain ranges across Europe, North and South America, using a combination of machine learning, multivariate and univariate analyses, and geochemical modeling. We found that 35 % of springs issuing from intact RGs (containing internal ice) have water quality below drinking water standards, compared to 5 % of springs connected to relict RGs (without internal ice). The interaction of ice and bedrock lithology is responsible for solute concentrations in RG springs. Indeed, we found higher concentrations of sulfate and trace elements in springs sourcing from intact RGs compared to water originating from relict RGs, mostly in specific lithological settings. Enhanced sulfide oxidation in intact RGs is responsible for the elevated trace element concentrations. Challenges for water management may arise in mountain catchments rich in intact RGs, and where the predisposing geology would make these areas geochemical RG hotspots. Our work represents a first comprehensive attempt to identify the main drivers of solute concentrations in RG water

Periglacial water paths within a rock glacier-dominated catchment in the Stepanek area, Central Andes, Mendoza, Argentina

In the region of the Stepanek rock glacier (69°19′/69°26′W, 32°55′/32°59′S), in the Province of Mendoza, Argentina, seasonal hydrochemical monitoring was carried out between 2013 and 2017. This paper describes underground and surface water flow, and their hydrochemistry, and provides an overview of how groundwater interacts with the rock glacier. The cryogenic basin of the study area where the hydrological flows originate has a surface area of 11.5 km2. The Stepanek rock glacier fills the valley and its permafrost influences water flow. Isotopic analyses of surface ephemeral streams and groundwater were made. Characteristic, naturally occurring δ2H and δ18O signatures of these samples indicate strongly that they are fed from within permafrost from the rock glacier, in response to the degradation of permafrost and melting of ground ice. Elevated values of Ni2+, Cd2+ and Zn2+ were detected in the meltwater runoff. Due to lithological factors, the Andean periglacial environment may indicate altitudinal differences in the hydrogeochemical results. Our hydrogeochemical research allows the interpretation of different water flows, directly observed or indirectly deduced, which cross the rock glacier. The new information allows for the development of a new conceptual rock glacier model that includes different flow paths. It is expected that this will become more important due to ongoing climate change.Fil: Trombotto, Dario Tomas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Sileo, Noelia Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Dapeña, Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotópica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotópica; Argentin

Evaluación de los aportes de la fotogrametríaterrestre en el estudio de glaciares de escombros(cordón del Plata, Mendoza, Argentina)

Evaluation of the photogrammetry contribution in the studies of rock glaciers(Cordón del Plata, Mendoza, Argentina)”. This work investigates the potential and limitsof terrestrial photogrammetry for studying rock glacier dynamics, and more especifically itsinterannual surface changes. Using a rather simple digital photogrammetric workflow, therestitution of two 3D-models was done thanks to multi-correlation of more than 100 imagesacquired in summers 2013 and 2014 on an active rock glacier in the Argentinian Andes.The quality of the output datasets is evaluated by comparing to GPS data collected on artificialtargets (XYZ) and along tracks (Z). Based on these results, we can consider ± 0.24 mas the margin of error that has to be taken into account to assess the surface changesbetween the two Digital Elevation Models (DEMs). Vertical differences affecting the rock glacierfront over the 15 months time lapse can then be quantified and interpreted in terms of geomorphologicalprocesses.Este trabajo investiga el potencial y los límites de la fotogrametría terrestreen el estudio de la dinámica de los glaciares de escombros, y en particular sus cambiossuperficiales interanuales. La contribución utiliza la restitución de dos modelos 3D, realizadagracias a la multi-correlación de más de 100 imágenes adquiridas entre los años 2013 y2014 de un glaciar de escombros activo en los Andes Centrales. La calidad de los datosproducidos es evaluada comparando los mismos con datos GPS medidos en blancos artificiales(XYZ) y a lo largo del camino (Z). Basado en estos resultados, se pudo estimar un margende error de ± 0,24 m, lo cual permitió evaluar los cambios superficiales entre los dosModelos Numéricos de Altitud (MNA). Las diferencias verticales que afectan el frente delglaciar de escombros estudiado en el intervalo de tiempo de 15 meses pudieron ser cuantificadase interpretadas en términos de procesos geomorfológicos

Recent evolution of the active layer in the Morenas Coloradas rock glacier, Central Andes, Mendoza, Argentina and its relation with kinematics

Between 2008 and 2016 the Morenas Coloradas rock glacier in the Central Andes of Mendoza showed different thermal characteristics at three monitoring sites in active layers, Balcón I (3560 m a.s.l.), Balcón I Superior (3590 m a.s.l.) and Balcón II (3770 m a.s.l.). These can be explained by various factors, not only external ones related to the climatic variability and altitude, but also by thermal-hydrological factors that destabilized its internal cryogenic structure. At Balcón I, situated on a sloping terrace of the rock glacier, a transient layer even showed definitive signs of permafrost degradation in the recent years, transforming it in a thermal talik. Long-term studies of surficial boreholes showed that the 0°C isotherm is higher in altitude than the active front of the rock glacier and it has risen 40 m in altitude since the 1990s. As consequence of the thermal changes of the active layer, the rock glacier shows abrupt movements, particularly in its terminal part. Thus geodesic measurements to obtain different speeds and directions were made. At the monitoring area of Balcón I Superior, which lies on a superimposed lobe, the geodesic measurement points revealed significant kinematic activity in the period May 2015 – February 2016, when the largest displacement was approximately 2 m to the South, developing an advance of the front over Balcón I. At Balcón II however, the points moved much less, in the order of 0.30 m yr-1. The present studies suggest that the largest cryogenic sedimentary movements are superficial, that is to say, they are located in the active layer and the supra-permafrost and are due to internal movements produced by melting water coming from the top of the cryoform, and from both sides of the upper basin of the valley.</jats:p

Permafrost model in coarse-blocky deposits for the Dry Andes, Argentina (28°-33° S)

In this work, a statistical permafrost distribution model for coarse-blocky deposits in the Dry Andes of Argentina (28-33°S) is presented. The empiric mathematical formulation was based on a logistic regression. The final model is a combination of two independent occurrence probability models: a) a mean annual air temperature-terrain ruggedness model and, b) a mean annual air temperature-potential incoming solar radiation model. For all cases, calibration was made according the complete geomorphological characterization of a periglacial basin with 250 km2. Lately, the results of probabilistic model were extrapolated to the whole study area in the Dry Andes and compared with the Argentine rock glacier inventory data base. High permafrost likelihood, in coarse debris, is expected above 4200 and 5700 m a.s.l., from south to north in the study area and covers a surface of approximately 1200 km2. Medium permafrost likelihood is expected above 3400 and 4200 m a.s.l. with a surface of 6178 km2 while low permafrost likelihood, occurs between 3000 and 3400 m a.s.l. with an area of 11.060 km2. These findings indicate that permafrost may occur in several types of coarse-blocky deposits in the Dry Andes, not only restricted to rock glaciers. Thermal properties of the ground in coarse-blocky deposits allow permafrost permanence, even under unfavourable climatic conditions.The performance of the permafrost model was also tested, considering the transition from cold paleoclimate Tardiglacial to present climatic conditions. During the warming, likely permafrost surface reduced from 56 to 13%. In the same way, rock glaciers with high and medium permafrost likelihood decrease from 62 to 30%, respectively while, rock glaciers with low likelihood and no permafrost category, increased 75% and 474%, respectively. Moreover, we identified some sites in which permafrost degradation is arguably expected. About that, 0.9% of the rock glaciers in the study area display possible permafrost degradation and 33% of them, likely permafrost degradation.</jats:p