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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.

The basement of the Central Andes located in central-western Argentina (31º20′S - 69º22′W) is composed by the Cuyania and Chilenia terranes which were amalgamated to Gondwana in the Early-Mid Paleozoic. Between the Precordillera (Cuyania) and Frontal Cordillera (Chilenia) there are exposures of marine metasedimentary rocks associated with mafic rocks with an E-MORB chemical signature that represent the remnants of an extensional basin developed between both terranes. The stratigraphic features and the distribution of the Early-Mid Paleozoic units along the Western Precordillera were constrained by remote sensing techniques. This allowed us to identify two stages in the evolution of the sedimentary in-fill of the marine basin: an initial stage (Mid-Late Ordovician) marked by widespread extensional tectonics and a finning-upwards sequence interbedded with volcanic-plutonic mafic rocks; and a Late Ordovician?-Devonian where the sedimentation was characterized by the development of coarsening-upwards sequences with low participation of mafic rocks. Flattened parallel folds associated with pre-Andean thrusts have locally a top-to-the SW vergence. These pre-Andean (Late Devonian) structures are the relics of the Chanic orogen whose double vergence is the result of the control exerted by previous structures related to the ordovician rifting. This is constrained by the residual and regional magnetic anomalies which reflect an important correlation between deep and surface structures. We propose the inception of a subduction zone with an eastward polarity on the proto-Pacific margin of Gondwana as the responsible for the compressive geotectonic framework that led to the closure of the Western Precordillera basin during the Late Devonian and the development of the Chanic thick-skinned-dominated orogen. Fil: Ariza, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina Fil: Boedo, Florencia Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Sanchez, Marcos Ariel. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina Fil: Christiansen, Rodolfo Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina Fil: Perez Lujan, Sofia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; Argentina Fil: Vujovich, Graciela Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Martínez, Myriam Patricia. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina

In central-western Argentina, a mafic-ultramafic belt occurs throughout the western margin of the Precordillera. This belt is interpreted as the suture zone between the Cuyania terrane and the Chilenia terrane, both accreted onto the Gondwana margin during the Early Paleozoic. The belt comprises rocks from different setting and age and can be divided into a northern (28-32°S, present coordinates) and a southern sector (south of 32°S). The northern sector includes MORB (Mid-Ocean-Ridge Basalts)-like metabasalt, metagabbro and minor metadiorite and wehrlite associated to marine sequences. The southern sector comprises serpentinite, ultramafic cumulate, mafic granulite and gneiss not exposed in the north as well as metagabbro, metabasalt and minor metahyaloclastite spatially associated to marine successions. Due to their geological similarities, the southern sector can be correlated with the Argentine Frontal Cordillera mafic-ultramafic belt exposed southwestwards. In the southern sector, the evolution of the belt began during the Late Neoproterozoic, with the generation of continental margin sequences related to MORB magmatism. This extensional regime would be related to the rifting of a continental block, that includes the Cuyania and Chilenia terranes, from southern Laurentia. During the Middle Ordovician-Early Devonian, a second extensional regime occurred along the entire belt, where passive margin successions along with E-MORB magmatism developed on a thinned continental crust. A pre-Devonian deformation phase D1, possibly related to the Ocloyic orogeny, only affected the southern sector of the belt. Whereas a deformation phase D2 is registered throughout the belt and it is related to the collision of the Chilenia terrane against West Gondwana in the Middle-Late Devonian.

This research based on geological and geophysical data encompasses the South Central Andes region between 28 S and 31 S. We observed a region of high-magnetic susceptibility linked to sources located beneath the Vinchina basin through anomaly calculations and enhancing techniques using aerial and terrestrial magnetic data. The Curie Point Depth (CPD) obtained from the magnetic anomalies reflects a cold crust of approximately 50 km thick with CPD values of up to 40 km. These results are consistent with those obtained by other authors by means of mineral, isotopic, and thermo-chronological analysis in clay levels of the Vinchina basin sedimentary infill. Fil: Weidmann, María Cecilia. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Ariza, Juan Pablo. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Sanchez, Marcos Ariel. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Gimenez, Mario Ernesto. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Christiansen, Rodolfo Omar. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Landslides are downslope mass movements, which implies the combination of natural complex processes and sometimes affect anthropic resources. Many researchers inventoried landslides in the Argentinian Andean Precordillera by using aerial photography, satellite images, geomorphological analyses and GPS measures. Those located in latitudes between 31°S and 34°S have been mainly linked to seismic activity. However, due to the inaccessibility of sites, permanent monitoring has proved difficult. In this contribution, we detect three active landslides occurring in the Andean Precordillera of San Juan province using Differential Interferometric Synthetic Aperture Radar (DInSAR) based time series techniques and preliminary characterize its geomorphology. We use data provided by ESA's Sentinel 1 (C-Band SAR), Sentinel 2 (Optical) acquired between October 2014 and December 2018. The observed landslides are located at unstable hillsides oriented to the West and their deposits could potentially end in the San Juan River. As a result of the time series analysis, we interpreted that the three landslides seem to be reactivated by Illapel Mw 8.3 Earthquake (September 16th, 2015). In addition, one of them, has an acceleration at the beginning of 2016, linked to rapid snow melt.

In central-western Argentina, a belt including marine metasedimentary rocks and mafic-ultramafic bodies occurs throughout the western margin of the Precordillera. The belt is considered as the suture zone between the poorly known Chilenia terrane and the Cuyania terrane, part of the composite West Gondwana margin. It is assigned to the Late Neoproterozoic-Early Devonian based on fossil fauna and radiometric ages. In the southern sector of this belt, in the Peñasco area, two units crop out. The Peñasco Formation comprises metasandstone and metapelite spatially associated with mafic metavolcanic and metahyaloclastic rocks. Metagabbro bodies intrude the succession. The Garganta del León Formation consists of metasandstone and scarce metapelite where tractive and deformational sedimentary structures are preserved. Both units are affected by low-grade metamorphism, but the main foliation S1 and crenulation cleavage S2 are better developed in the Peñasco Formation rocks. U-Pb data on detrital zircon of two metasandstone samples from these units show a dominant detrital input from sources with 1.0–1.3 and 0.65–0.53 Ga ages. Detritus may come from reworked sedimentary units or from igneous/metamorphic complexes from the Cuyania terrane basement that was possibly exhumed in the Ocloyic orogen. A Gondwanan provenance for the Late Neoproterozoic-Cambrian population would also be plausible. A ca. 460 Ma zircon population in the Garganta del León Formation is interpreted to be derived from the Famatinian Arc. This would imply that the deposition of the sediment occurred after the collision of the Cuyania terrane against West Gondwana, and that the Ocloyic orogen acted as a barrier for detritus from the Famatinian Arc and other rocks further east. Fil: Boedo, Florencia Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Perez Lujan, Sofia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; Argentina Fil: Naipauer, Maximiliano. 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; Argentina Fil: Vujovich, Graciela Irene. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Martins Pimentel, Márcio. Universidade do Brasília; Brasil Fil: Ariza, Juan Pablo. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina Fil: Barredo, Silvia Patricia. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina

The Argentine Precordillera is located in the central western region of Argentina, within the Central Andes. Throughout its westernmost sector, mafic and ultramafic bodies including serpentinites, mafic granulites, basaltic dikes/sills and pillow lavas are associated with metasedimentary rocks deposited in a deep marine and slope environment. These magmatic units, which are known as the Precordillera ultramafic-mafic belt, are considered to have a range of Early Paleozoic age based on published UePb zircon ages and fossil fauna. The entire sequence shows the effects of complex polyphase Paleozoic deformation and was subjected to a low grade metamorphism considered to be of middle-late Devonian age. The chemistry of the Peñasco and Cortaderas mafic dikes and sills in the southern part of this belt, which are largely plagioclase þ clinopyroxene-bearing tholeiitic basalts, is the focus of this study. These volcanic rocks all have E-MORB-like major and trace element and εNd (þ6.0 to þ9.3) signatures with similarities to those previously reported throughout the belt. The new descriptions and major and traceelement analyses presented here confirm the similarity of the E-MORB-like chemistry of the Early Paleozoic mafic rocks along the entire belt, which spans some 500 km in length. There is a general consensus that these units are exposed as a consequence of the collision of the Chilenia terrane against the Gondwana margin during the middle to late Devonian, but the details of timing, the origins of the continental blocks and the nature of the collision are still debated. The results presented support the western Precordillera basaltic dikes/sills as having formed in the early stages of oceanic rifting along the Gondwana (Precordillera) continental margin with their E-MORB-like character reflecting mixing of depleted and enriched mantle and continental lithospheric sources. Fil: Boedo, Florencia Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina Fil: Vujovich, Graciela Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina Fil: Kay, S. M.. Cornell University; Estados Unidos Fil: Ariza, Juan Pablo. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Fisicas y Naturales. Instituto Geofisico Sismologico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Perez Lujan, Sofia Beatriz. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina