Central Andes Of Argentina Research Articles

Ceratophryid frogs in the late Miocene of central Andes of Argentina: insights on the paleoenvironment of Palo Pintado Formation

ABSTRACT Ceratophryid frogs inhabit the lowlands of South America and exhibit greater diversity in the semiarid Gran Chaco. The presence of Ceratophryidae dates back to the late Miocene on the eastern slopes of the Andes in Argentina. Herein, we describe the remains of Ceratophrys from late Miocene of Palo Pintado Formation (Salta, Argentina). Fragmentary bones were recovered from the base of the unit in beds dated between 8 and 7.7 million years ago. The specimen IBIGEO-P141 exhibits the fusion of dentary and mentomeckelian bones forming a fang, a sharp-edged lower jaw, and sculptured bones as Ceratophryidae. The granular pattern of sculpturation, differences between pars facialis and pars dentalis of maxillary, and the shape of lower jaw, support its assignment to the genus Ceratophrys. Combined bioclimatic data and geographic distribution of living Ceratophrys indicate a strong influence of precipitation variables in the distribution of these frogs with adaptations to survive long dry periods. These facts suggest a seasonal rainfall with a well-defined dry season during the deposition of lower levels of Palo Pintado Formation. The palaeoclimatic conditions resemble those occurring in the actual semiarid Chaco, and reveal that the historical geographic distribution of Ceratophryidae was retracted eastward due to the Andean uplift.

Understanding arsenic-ulexite interactions in evaporite environments: Evidence from XRPD, micro-XRF, micro-FT-IR, and XPS studies

World-class borate deposits often form from As-rich waters, this study addresses the understudied association of arsenic (As) species with evaporite borates, focusing on the Puna region's borate deposits (Central Andes of Argentina). The research aims to characterize the association between borate minerals and high As concentrations in brines and thermal waters. To achieve this, five borate samples were collected from the Olaroz salt flat nucleus and thermal springs, alongside associated water samples. Comprehensive analytical techniques, including ICP-MS, ICP-OES, synchrotron-based micro-XRF, XRPD, Rietveld analysis, micro-FT-IR, and XPS, were employed to determine bulk and surface chemical compositions, mineral identification, and solid speciation of As and boron. The study reveals that under oxidizing conditions and in absence of organic matter, aqueous arsenic species interact with ulexite through a stepwise process involving charge neutralization, cationic bridge formation, and surface complex formation with polyborate and As(V) oxyanions. However, in environments associated with microbial mats or organic-rich sediments, the dissolved As(V) is reduced to As(III), which forms complexes with functional groups of organic matter. The coexistence of As(III) and As(V) in specific layers suggests potential remediation strategies targeting organic matter for the removal of the more toxic As(III) in similar geological settings.

The Cretaceous of the Neuquén Basin in the Central Andes

Abstract The Neuquén Basin, located at the foothills of the Central Andes of Argentina, with superb and extended exposures, is a natural laboratory. It is important not only for its continuous sedimentary record and superb palaeontological biota but also for its significant economic hydrocarbon resources. This synthesis is intended to provide an update only on the Cretaceous timespan in the basin development. It is characterized by a succession of sedimentary rocks that were deposited in different environments over time, interspersed with volcanic rocks associated with an active volcanic arc. High-precision geochronology dating on the tuffs establishes robust chronological ages to constrain the different stages. As this brief review only shows a fragment of the information presently available, an effort has been made to compile a comprehensive and up-to-date bibliography to compensate for the brevity of the text.

On the oviposition of Homonota aff. darwinii in the Puna region of the Central Andes of Argentina

On the oviposition of Homonota aff. darwinii in the Puna region of the Central Andes of Argentina

RANGE EXTENSION OF <i>Synbranchus marmoratus</i> (SYNBRANCHIDAE) TOWARDS ARGENTINA’S CENTRAL ANDES

This work provides a new record that extends the western limit of the geographic distribution of Synbranchus marmoratus towards the Central Andes of Argentina, in the Department of Calingasta, Province of San Juan. In addition, an update of the geographical distribution map of the species in the country is provided based on this record and a complete literature review. We collected a specimen of this species on 12 September 2016 during an ichthyofaunal survey of high Andean rivers. This record corresponds to the westernmost distribution in the country. This finding is interesting since this species is considered an indicator of the ichthyofauna of the Biogeographic Provinces Greats Rivers and Pampean, while the ichthyofauna of the study area of this new record belongs to the Andean Cuyo Province.

Synoptic fingerprints of Zonda wind from a statistical prediction model

AbstractZonda wind is a typical downslope windstorm over the eastern slopes of the Central Andes in Argentina, which produces extremely warm and dry conditions and has substantial socioeconomic impacts. In this study, we propose a new statistical model for Zonda prediction based on the “synoptic fingerprints” of atmospheric diagnostic variables from ERA5. The model combines principal component analysis (PCA) and logistic regression to establish a relationship between the observed occurrence and the PCA loading component of a predictor variable. This approach enables us to determine the probability of Zonda occurrence at selected stations and identify the synoptic structure features (fingerprints) associated with Zonda events. The obtained fields successfully discriminate between Zonda and non‐Zonda events, suggesting that the available information in the reanalysis data is sufficient for predicting the presence of Zonda. The synoptic fingerprints generated by the model reveal a cross‐barrier pressure gradient resulting from a negative geopotential height anomaly at low levels. The cross‐barrier flow remains unimpeded by the Andes, leading to forced vertical motions on the windward side, accompanied by cooling and precipitation. On the lee side, sinking motions, warming and drying are observed, further facilitated by favourable mid‐ and upper‐level conditions that establish the Zonda wind. The model performs comparably to previous research, with the best results achieved using low‐level variables as predictors. Key performance measures, including the area under the receiver operating curve (ROC) (AUC) of 0.9468 and a Brier score lower than 0.1, demonstrate the model's effectiveness. Using a 0.5 threshold, the accuracy, F1 score and correct alarm ratio (CAR) all exceed 88%, with a probability of detection (POD) higher than 90%. Studies on this type of downslope windstorm are scarce in South America, making this work a significant contribution to understanding synoptic‐scale atmospheric structures associated with Zonda occurrences.

Germination and Early Seedling Growth of High Andean Native Plants under Heavy Metal Stress

The development of large-scale mining activity along the Central Andes of Argentina (CAA) has generated significant amounts of waste materials containing heavy metals. Phytoremediation is a promising eco-friendly, low-cost, and effective technology for the removal of heavy metals. The present study aimed to identify two native dominant species from the CCA, Adesmia subterranea and A. pinifolia, as metal-tolerant plant species for the first time, by evaluating the germination and early seedling growth at different concentrations (ppm) of Cd (3, 4.5 and 6), Ni (150, 225 and 300), As (20, 30 and 40), and Hg (0.8, 1.2 and 1.6) Early seedling growth was found to be more sensitive to heavy metals than germination. Ni and As exhibited the greatest inhibitory effect on both species’ germination percentages. In contrast, with Cd and Hg, no inhibitory effect was recorded. Root length, metal tolerance index, and fresh and dry weight were stimulated with Hg. However, the phytotoxic effect was greater as the concentration of Ni, As, and Cd increased. As an overall conclusion, the order of toxicity for these species can be classified as Ni > As > Cd > Hg. Therefore, Adesmia species could be considered as candidates for phytoremediation of soils contaminated with Hg and low concentrations of Cd.

Tectonic framework of surface and blind structures from neotectonic and geophysical (gravimetry) analyses, Central Andes of Argentina

This work describes new evidence of N–S and oblique trending surface and blind structures in the La Cantera-Gualilán tectonic depression in the Central Precordillera, San Juan Province, Argentina. Two main N–S Quaternary thrusts cross longitudinally the valley located ∼60 km west of San Juan city (30° 50′- 31° 17′ S and 68° 55′- 69° 05′ W). One of them is located in the eastern piedmont of the Sierra de La Invernada (San Juan Fault) and the other in the western piedmont of the Sierra de La Cantera (La Cantera Fault System), although the northward continuation of this structure has not yet been confirmed.Besides, a smooth water divide or “portezuelo” controlled by an oblique transpressive structure (Divisadero Coba Rubia Fault) separates two N–S elongated river basins with opposite water flow directions. One of these is the Gualilán River, which flows from south to north, and the other corresponds to the La Cantera River, running from north to south.In the present work, we describe some new natural exposures and subtle geomorphological evidence of Quaternary structures identified in the Gualilán-La Cantera tectonic depression. We also use regional and local gravity data to analyze and interpret gravity anomalies related to these surface or blind active structures. Then, based on our geologic and geophysical interpretations, we infer the presence of several, buried cross-strike structures with NW and NE trends, one of them coincident with the drainage divide between the Gualilán and La Cantera opposite river basins, possibly related to the Coba Rubia Fault. Also, we suggest the northward continuation of the La Cantera Fault System (LCFS) as a buried structure in coincidence with the Gualilán River alluvial plain. In this sense, the gravity response of the basement and these river sub-basins shows a close relationship with the surface and subsurface structures. We propose that the oblique structures could represent pre-existing crustal fabrics reactivated during the Andean orogeny, segmenting the N–S Precordillera fold and thrust belt system. Finally, according to the analyzed neotectonic and gravimetric features, we consider the La Cantera-Gualilán Valley as a potentially seismogenic source in this intraplate portion of the Andean Precordillera, crossed by several N–S and oblique surficial and buried/blind active structures. These tectonic features could play a significant role in a regional seismic hazard assessment.

The Charrarruca porphyry-type alteration zone: New evidence of mineralizing Late Cretaceous-Eocene magmatism in the Southern Central Andes of Argentina

The Charrarruca porphyry-type alteration zone is located in the northern part of the Andacollo Mining District (AMD), placed in the northern Neuquén Precordillera, (Argentina). Potassic, chloritic-carbonatic, sericitic, and propylitic alteration halo of ∼1.5 km2 affects an andesitic/dacitic subvolcanic body. These rocks, with arc affinity and Upper Cretaceous-Paleogene age (65 ± 2.5 Ma), derived from a magma evolved under normal crust thickness conditions, allowing the correlation with the intrusive facies of the Naunauco Group. The petrogenetic characteristics of these rocks attest to indications of the fertility of this magmatism, turning into a prospective guide for the unexplored Upper Cretaceous–Eocene Neuquén porphyry copper metallogenic belt.

Assessing a data-driven approach for monthly runoff prediction in a mountain basin of the Central Andes of Argentina

In the semi-arid Central Andes of Argentina, the water from snowmelt runoff plays a fundamental role as a provider of ecosystem services. Nowadays, the global climate change has an observable negative impact on this area, due, principally, to the decrease in both liquid and solid rainfall, with the consequent decrease in water availability. In this context, runoff prediction acquires vital importance for the integrated water resources management. The aim of this study is to investigate the performance of the Support Vector Regression (SVR) technique in predicting monthly discharges with 1-month lead-time in the Tupungato River basin in the Central Andes of Argentina. This methodology has never been applied before in this mountainous region. Different inputs, like meteorological data and satellite-based snow cover area estimates from MODIS, were analyzed in order to identify the suitable inputs predictors to forecast monthly streamflow. The results were compared against the results derived from a Classification and Regression Tree (CART) model and, also, against an Auto-regressive Integrated Moving-average (ARIMA) model. Different metrics were used to evaluate the performance of the SVR tests in reproducing streamflow observations at the basin outlet. The coefficient of determination for each of the analyzed tests lays between 0.75 and 0.89 in the validation set. The comparison with the other models showed a significant improvement in performance of SVR in respect of CART and ARIMA model. SVR models proved a promising approach to support water management and decision making for productive activities, potentially also in other basins in the region.

Behavioral responses of two small‐sized rodents, Phyllotis vaccarum and Abrothrix andina, to energy challenges of high‐altitude habitats in the Andes Mountains

AbstractIn mountain environments, both temperature and food availability vary strongly with altitude, leading to a major challenge to the thermo‐energetic balance of organisms. In this sense, the behavioral repertoire is crucial for animals' adequacy because it implies a short‐term response in the face of environmental changes. In this paper, we explored the behavioral versatility of Phyllotis vaccarum and Abrothrix andina (Rodentia: Cricetidae), two of the mammal species with the highest altitudinal distribution worldwide. By radiotelemetry, we analyzed the activity pattern, home range, and microhabitat selection in populations of both species inhabiting at 2300 and 3100 m altitude in the Central Andes of Argentina. We found that A. andina was diurnal at 3100 m and cathemeral at 2300 m a.s.l., while P. vaccarum was nocturnal at both elevations. Moreover, home range size was larger in A. andina males at 3100 m in contrast to females at identical altitude and males at 2300 m; while, in P. vaccarum, there were no differences according to altitude or sex. Furthermore, we recorded a complex and species‐specific microhabitat selection pattern at different altitudes. Finally, the magnitude of behavioral variability was higher in A. andina than in P. vaccarum for all the traits analyzed. These results are discussed with emphasis on the impact of behavioral traits and their plasticity for species adequacy in high‐altitude environments.

Microhabitat use and selection by Pristidactylus scapulatus (Squamata Leiosauridae) in the Puna region of the Central Andes in Argentina

Understanding a species use of space is important as it provides information about the potential resources available in its habitat. The objective of this work was to evaluate the use and selection of microhabitat as it relates to availability for Pristidactylus scapulatus in the Puna region of the Central Andes in Argentina. The work was carried out at Quebrada de La Puerta in the province of San Juan and data recorded for the species included microhabitat use and availability according to established categories. To assess microhabitat selection, we applied a design of usage vs availability and calculated the Manly index to obtain a function of resource selection. The species utilised the rock microhabitat in greater proportion with respect to its availability, and in lesser measure utilised shrub and bare soil, whereas it rejected the use of cactus and dead leaves substrate. The Manly index showed that the selection of rock substrate was significant with respect to the other microhabitats. We conclude that this population of P. scapulatus has clearly saxicolous habits, though it is necessary to be aware of other aspects of its natural history to truly understand how its microhabitat selection relates to feeding or reproduction in hostile environments like the Puna. In this way we contribute to the scarce existing knowledge of its biology and we provide an information basis for the creation of future priority areas for conservation and for habitat management plans in Puna environments.

Thermal biology and locomotor performance of the Andean lizardLiolaemus fitzgeraldi(Liolaemidae) in Argentina

AbstractEctotherms thermoregulate to maintain their body temperature within the optimal range needed for performing vital functions. The effect of climate change on lizards has been studied as regards the sensitivity of locomotor performance to environmental temperatures. We studied thermoregulatory efficiency and locomotor performance forLiolaemus fitzgeraldiin the Central Andes of Argentina. We determined body temperature, micro‐environmental temperatures and operative temperatures in the field. In the laboratory, we measured preferred temperatures and calculated the index of thermoregulatory efficiency. We estimated the thermal sensitivity of locomotion by measuring sprint speed (initial velocity and long sprint) and endurance at five different body temperatures. Body temperature was not associated with either micro‐environmental temperature, nor did it show differences with preferred temperatures. Thermoregulatory efficiency was moderate (0.61). Initial velocity and long sprint trials showed differences at different temperatures; however, endurance did not. Moreover, the optimal temperatures for the performance trials showed no significant differences among themselves. We conclude thatLiolaemus fitzgeraldihas thermal sensitivity in locomotor performance with respect to body temperature and that it is an eurythermic lizard that experiences a large variation in body temperature and that has thermal flexibility in the cold.

Downstream changes in quartz OSL sensitivity in modern river sand reflects sediment source variability: Case studies from Rocky Mountain and Andean rivers

OSL (optically stimulated luminescence) sensitivity of quartz has been shown to either (1) record downstream sediment transport related to increased number and duration of light exposure cycles or (2) be a function of source geology, presenting a potential tool to track sediment provenance. To test these competing models this study leverages a suite of modern river samples from an extensional basin system in the Rocky Mountains of western USA (Bear River) and a retroarc foreland basin system in the southern Central Andes of Argentina (Río San Juan) to understand the relationships among quartz luminescence sensitivity, sediment transport distance, and catchment lithologies. We compare our results with petrographic analysis of the river sand composition, and characterization of the lithology and morphometrics of the river catchments. Samples taken along the Bear River and its major tributaries in the Rocky Mountains show a progressive downstream decrease in quartz OSL sensitivity that records variation in sediment provenance and steady contribution of lower OSL sensitivity quartz recycled from Palaeozoic passive margin stratigraphy. Andean river sand samples from the Rio San Juan network exhibit pervasive low sensitivity quartz derived from Andean arc volcanic rocks and recycled Neogene foreland basin strata. These modern river sand data do not show increased sensitivity with transport distance and instead indicates that in these landscapes, quartz OSL sensitivity is an intrinsic property of the source rock. Our study shows that river sands primarily composed of older, recycled low-strained quartz derived from quartzite lithologies exhibit the highest quartz sensitivity values. Moderate quartz OSL sensitivity values are observed in rivers with young igneous quartz derived directly from the volcanic and intrusive rocks. Conversely, microcrystalline quartz in chert lithic grains or polycrystalline quartz found in composite metamorphic lithic grains record the lowest quartz OSL sensitivity values. Determining the controlling factors of quartz sensitivity in river sand provides a current baseline for resolving paleogeographic and paleodrainage histories in the sedimentary record and provides further understanding of how sediments are eroded, transported, and deposited in fluvial systems with diverse tectonic settings and geologic source rocks.

Hiking and livestock favor non-native plants in the high Andes

Hikers and livestock using mountain trails damage native vegetation and act as seed vectors, thus favouring the spread of non-native plants. We evaluated the effect of trails and livestock abundance on the success of non-native plants in the arid central Andes of Argentina. We surveyed six trails, covering elevations between 2400 and 3570 m a.s.l. and recorded non-native and native vegetation using transects distributed along the elevational gradient and spanning distances up to 22 m from the trail. We assessed how non-native occurrence, richness and cover varied with distance from the trail, intensity of use by livestock, native plant community composition and elevation. We found that trails favoured non-native occurrence, but did not influence richness and cover, while livestock favoured non-native occurrence, richness and cover. Non-native richness and cover decreased with elevation and varied with native community composition. In addition, non-native richness was positively correlated with native shrub cover suggesting possible facilitative interactions. Our results show that despite strong environmental filtering that leads to decreasing non-native abundance with increasing elevation, non-natives occur up to the upper limits of vegetation, and that trails and livestock favour non-native spread in these mountains.Second Abstract in native language.

Magmatic evolution and architecture of an arc-related, rhyolitic caldera complex: The late Pleistocene to Holocene Cerro Blanco volcanic complex, southern Puna, Argentina

Abstract Through the lens of bulk-rock and matrix glass geochemistry, we investigated the magmatic evolution and pre-eruptive architecture of the siliceous magma complex beneath the Cerro Blanco volcanic complex, a Crater Lake–type caldera complex in the southern Puna Plateau of the Central Andes of Argentina. The Cerro Blanco volcanic complex has been the site of two caldera-forming eruptions with volcanic explosivity index (VEI) 6+ that emplaced the ca. 54 ka Campo Piedra Pomez ignimbrite and the ca. 4.2 ka Cerro Blanco ignimbrite. As such, it is the most productive recent explosive volcano in the Central Andes. The most recent eruptions (younger than 4.2 ka) are dominantly postcaldera effusions of crystal-rich domes and associated small explosive pulses. Previous work has demonstrated that andesitic recharge of and mixing with rhyolitic magma occurred at the base of the magma complex, at ~10 km depth. New isotopic data (Sr, Nd, Pb, and O) confirm that the Cerro Blanco volcanic complex rhyolite suite is part of a regional southern Puna, arc-related ignimbrite group. The suite defines a tight group of consanguineous siliceous magmas that serves as a model for the evolution of arc-related, caldera-forming silicic magma systems in the region and elsewhere. These data indicate that the rhyolites originated through limited assimilation of and mixing with upper-crustal lithologies by regional basaltic andesite parent materials, followed by extensive fractional crystallization. Least squares models of major elements in tandem with Rayleigh fractionation models for trace elements reveal that the internal variations among the rhyolites through time can be derived by extensive fractionation of a quartz–two feldspar (granitic minimum) assemblage with limited assimilation. The rare earth element character of local volumes of melt in some samples of the Campo Piedra Pomez ignimbrite basal fallout requires significant fractionation of amphibole. The distinctive major- and trace-element characteristics of bulk rock and matrix of the Campo Piedra Pomez and Cerro Blanco tephras provide useful geochemical fingerprints to facilitate regional tephrochronology. Available data indicate that rhyolites from other neighborhood centers, such as Cueros de Purulla, share bulk chemical characteristics with the Campo Piedra Pomez ignimbrite rhyolites, but they appear to be isotopically distinct. Pre-eruptive storage and final equilibration of the rhyolitic melts were estimated from matrix glass compositions projected onto the haplogranitic system (quartz-albite-orthoclase-H2O) and using rhyolite-MELTS models. These revealed equilibration pressures between 360 and 60 MPa (~10–2 km depth) with lowest pressures in the Holocene eruptions. Model temperatures for the suite ranged from 695 to 790 °C. Integrated together, our results reveal that the Cerro Blanco volcanic complex is a steady-state (low-magmatic-flux), arc-related complex, standing in contrast to the flare-up (high-magmatic-flux) supervolcanoes that dominate the Neogene volcanic stratigraphy. The silicic magmas of the Cerro Blanco volcanic complex were derived more directly from mafic and intermediate precursors through extensive fractional crystallization, albeit with some mixing and assimilation of local basement. Geochemical models and pressure-temperature estimates indicate that significant volumes of remnant cumulates of felsic and intermediate composition should dominate the polybaric magma complex beneath the Cerro Blanco volcanic complex, which gradually shallowed through time. Evolution to the most silicic compositions and final equilibration of some of the postcaldera domes occurred during ascent and decompression at depths less than 2 km. Our work connotes an incrementally accumulated (over at least 54 k.y.), upper-crustal pluton beneath the Cerro Blanco volcanic complex between 2 and 10 km depth. The composition of this pluton is predicted to be dominantly granitic, with deeper parts being granodioritic to tonalitic. The progressive solidification and eventual contraction of the magma complex may account for the decades of deflation that has characterized Cerro Blanco. The presently active geothermal anomaly and hydrothermal springs indicate the Cerro Blanco volcanic complex remains potentially active.

Unsaturated mine tailings disposal

Filtered tailings is the disposal technology that is most likely to yield an unsaturated state of the tailings. Such state has important benefits. A dam to contain the mine wastes is no longer needed, the risk of polluting seepage is minimized, and liquefaction of tailings is prevented. Filtering also allows most of the water mixed with the tailings to be recovered and reused in the process. The resulting material can be handled with traditional soil moving equipment to form a stack, for instance. While the idea is simple, the multiple phenomena involved in the tailings unsaturated disposal make up a complex process. The present work is based on a case study, the Casposo Mine filtered tailings disposal facility, located in the central Andes of Argentina. Throughout ten years of operation, a series of field and laboratory studies have been carried out to characterize the phenomena that intervene in the disposal of filtered tailings. Two stages were studied in detail: air drying upon tailings discharge and tailings compression under the weight of the subsequent lifts of the stack. Flocculant agents were found to have an outstanding influence in the tailings behaviour. Because of the multiple influencing factors, the process outcome (namely, the tailings water content and their void ratio) is highly variable. To deal with such variability, projects must include enough redundancy. In this regard, the case study’s incorporation of waste rock layers interspersed between tailings layers was a successful experience.

Could plasticity mediate highlands lizards' resilience to climate change? A case study of the leopard iguana (Diplolaemus leopardinus) in Central Andes of Argentina.

The predicted rise of global temperatures is of major concern for ectotherms because of its direct impact on their behavior and physiology. As physiological performance mediates a species' resilience to warming exposure, physiological plasticity could greatly reduce the susceptibility to climate change. We studied the degree to which Diplolaemus leopardinus lizards are able to adjust behavioral and physiological traits in response to short periods of temperature change. We used a split cross design to measure the acclimation response of preferred body temperature (Tp), and the thermal performance curve of resting metabolic rate (RMR) and evaporative water loss (EWL). Our results showed that plasticity differs among traits: whereas Tp and EWL showed lower values in warm conditions, the body temperature at which RMR was highest increased. Moreover, RMR was affected by thermal history, showing a large increase in response to cold exposure in the group initially acclimated to warm temperatures. The reduction of EWL and the increase in optimal temperature will give lizards the potential to partially mitigate the impact of rising temperatures in the energy cost and water balance. However, the decrease in Tp and the sensitivity to the warm thermal history of RMR could be detrimental to the energy net gain, increasing the species' vulnerability, especially considering the increase of heat waves predicted for the next 50years. The integration of acclimation responses in behavioral and physiological traits provides a better understanding of the range of possible responses of lizards to cope with the upcoming climatic and environmental modifications expected as a result of climate change.

Rock glacier and protalus rampart inventory in Las Salinas river basin, Central Andes of Argentina

This paper presents a detailed rock glacier and protalus rampart inventory from Las Salinas river basin, an arid subtropical mountain hydrological system (between 31°02’ and 31°22’ S latitude) located in the northern sector of the Central Andes of Argentina, where permafrost and cryogenic processes prevail. The inventory is based on a geomorphological characterization by means of optical remote sensing and field description data. The study region covers 630 km2, with 3.25% of the area containing 405±8.2 rock glaciers and protalus ramparts in total, of which 231±2.5 are considered protalus rampart and 49±2 are considered active, 61±1 inactive and 64±3 fossil rock glaciers. Frequency ratio and logistic regression were used as statistical methods to determine the relationship between the distribution of these periglacial landforms and different geological, morphometric and climatic variables as elevation, potential incoming solar radiation, slope, aspect and lithology. Results show that elevation, lithology, and aspect are the most influencing factors for the occurrence of active rock glaciers. According to rock glaciers and protalus ramparts distribution, the permafrost occurrence probability is above 3690 m a.s.l. (current and high periglacial environment). However, some inactive rock glaciers and protalus rampart were found below this elevation, thus between 3300 and 3690 m a.s.l. the landscapes are dominated by an unstable periglacial environment.

Low-enthalpy geothermal energy resources in the Central Andes of Argentina: A case study of the Pismanta system

Geothermal energy resources are necessary to meet the increasing energy requirements worldwide and reduce the impact of climate change, particularly in developing countries. The aim of this study is the investigation of the low-enthalpy geothermal system of Pismanta, in the Central Andes of Argentina, to evaluate the possibility of power generation or direct use applications. Results indicate a circulation of meteoric water to the reservoir located in the Iglesia Basin, reaching a maximum depth of 2500 m. A background heat flow of 60 mW/m2 raises the temperature of the reservoir to approximately 95 °C resulting in a mean thermal gradient of 30 °C/km. The preliminary evaluation of four binary cycle energy conversion plants suggests a gross power generation range of 30–280 kW and the capacity of using the remaining heat for direct use applications such as drying of fruits, greenhouses, food processing and membrane distillation processes to solve arsenic problems in freshwater, among others.