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A hydrogeological study of the shallowest part of the halite nucleus of the Salar de Atacama is presented, focusing on the isotopic variability in δ18O and δ2H (SMOW) in the brine. It is observed that intensive brine extraction has induced upward vertical flows from the lower aquifer, which presents with a lighter isotopic composition (δ18O: −0.87‰ to −2.49‰; δ2H: −26.04‰ to −33.25‰), toward the upper aquifer, which has more variable and enriched isotopic values. Among the possible explanations for the lighter isotopic composition of the lower aquifer waters is the influence of paleolakes formed during the wetter periods of the Late Pleistocene and Holocene that recharged the underlying aquifers. The geological structure of the Salar, including faults and the distribution of low-permeability layers, has played a determining role in the system's hydrodynamics. This study emphasizes the need for continuous and detailed monitoring of the isotopic composition to assess the sustainability of the water resource in response to brine extraction and future climate changes. Additionally, it suggests applying this methodology to other salt flats in the region for a better understanding of hydrogeological processes in arid zones. The research provides an integrative view of the relationship between resource extraction, water management, and ecosystem conservation in one of the most important salars in the world. [ABSTRACT FROM AUTHOR]

Las problematizaciones académicas sobre la identidad son un insumo clave para analizar las dinámicas de la etnicidad en el campo sociopolítico lickanantay actual. A partir de lo anterior, abordamos mediante un caso de estudio el intento de ciertos subgrupos de desmembrarse de su unidad sociopolítica mayor a partir de acciones que buscan obtener validación mediante la puesta en diálogo entre el saber local y el académico. El subgrupo pone así en tensión las relaciones con la comunidad mayor de pertenencia y logra, al menos, mejorar su posición dentro de ella.

A hydrogeological study of the shallowest part of the halite nucleus of the Salar de Atacama is presented, focusing on the isotopic variability in δ18O and δ2H (SMOW) in the brine. It is observed that intensive brine extraction has induced upward vertical flows from the lower aquifer, which presents with a lighter isotopic composition (δ18O: −0.87‰ to −2.49‰; δ2H: −26.04‰ to −33.25‰), toward the upper aquifer, which has more variable and enriched isotopic values. Among the possible explanations for the lighter isotopic composition of the lower aquifer waters is the influence of paleolakes formed during the wetter periods of the Late Pleistocene and Holocene that recharged the underlying aquifers. The geological structure of the Salar, including faults and the distribution of low-permeability layers, has played a determining role in the system’s hydrodynamics. This study emphasizes the need for continuous and detailed monitoring of the isotopic composition to assess the sustainability of the water resource in response to brine extraction and future climate changes. Additionally, it suggests applying this methodology to other salt flats in the region for a better understanding of hydrogeological processes in arid zones. The research provides an integrative view of the relationship between resource extraction, water management, and ecosystem conservation in one of the most important salars in the world.

Copyright of Runa: Archivo para las Ciencias del Hombre is the property of Runa: Archivo para las Ciencias del Hombre and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Habiendo vivido junto al dinamismo geológico de la cuenca del Salar de Atacama (Chile) por milenios, el pueblo Lickanantay ha acumulado abundantes datos observacionales y ceremoniales acerca de la naturaleza volcánica que les rodea y la participación de volcanes en procesos más amplios de formación cosmoecológica. Sin embargo, la vulcanológica formal no ha establecido un diálogo sustantivo con estos conocimientos. A través de una colaboración intercultural, este artículo expone lo que llamamos ‘vulcanología Lickanantay’ —o el sistema Lickanantay de conocimiento sobre volcanes, relaciones volcanes-humanos e interdependencia geocósmica— con el objetivo de hacerla disponible para la comunidad vulcanológica general. Primero, describimos las características básicas de la vulcanología Lickanantay. Luego nos enfocamos en el campo geotérmico de El Tatio para ofrecer una aproximación situada. Finalmente, delineamos algunos elementos para la gestión del riesgo volcánico desde una perspectiva Lickanantay. En nuestras conclusiones sugerimos que la vulcanología Lickanantay invita a pensar lo ‘indígena’ no como un conjunto finito de conocimientos y prácticas sino como una demanda por autonomía territorial y epistemológica, y que es sólo reconociendo esa demanda que la vulcanología podrá responder al llamado de la descolonización de la ciencia.

InSAR coherence-change detection (CCD) is a promising remote sensing technique that is able to map areas affected by torrential sediment transport triggered by flash floods in arid environments. CCD maps the changes in the interferometric coherence between synthetic aperture radar images (InSAR coherence), a parameter that measures the stability of the radar signal between two different SAR images, i.e., data acquisitions. In arid environments, such changes are mainly due to changes in the surface. However, the residual effect of other factors on the InSAR coherence cannot be completely excluded. Therefore, CCD-based maps contain the uncertainty of whether the detected changes are actual changes in the observed surface or just errors related to those residual effects. Thus, in this paper, the results of four CCD mapping methods, with different degrees of complexity and sensitivity to the different factors affecting the InSAR coherence, are compared in order to evaluate the existence of the errors and their importance. The obtained CCD maps are also compared with changes in satellite optical images and a field campaign. The results lead to the conclusion that CCD maps are reliable in the identification of the zones affected by sediment transport, although the precision in the delimitation of the affected area remains an open issue. However, highly rugged relief areas still require a thorough analysis of the results in order to discard the geometric effects related to the perpendicular baseline. [ABSTRACT FROM AUTHOR]

Copyright of REDER: Revista de Estudios Latinoamericanos sobre Reducción del Riesgo de Desastres is the property of Corporacion Gestion de Riesgos y Desastres (GRID-Chile) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Coherence change detection (CCD) is a remote sensing technique used to map phenomena that, under certain conditions, can be directly related to changes in Interferometric SAR (InSAR) coherence. Mapping the areas affected by sediment transport events in arid environments is one of the most common applications of CCD. However, the reliability of these maps remains an unsolved issue. This paper focuses on verifying that InSAR coherence is indeed able to detect all the fluvial sediment transport events that have actually mobilised sediments in arid environments by building a classification model and validating its results. The proposed methodology is tested in three study areas in Salar de Atacama, Chile, using three years of Sentinel data plus a fourth year for validation, and meteorological records of rainfall, the relative humidity of the air and snow cover. The results prove that InSAR coherence can be used to remotely detect sediment transport events related to flash floods in arid environments, that it might have a greater detection ability than meteorological records and that the perpendicular baseline does have a relevant effect on the InSAR coherence that needs to be considered. All these findings will increase the reliability of maps based on InSAR coherence. In addition, the proposed method will allow focusing the mapping tasks only on the relevant dates and, once calibrated, the classification model will enable the automatised remote detection of new events. [ABSTRACT FROM AUTHOR]

ABSTRACT The lacustrine systems of La Brava and La Punta, located in the Tilopozo sector in the extreme south of Salar de Atacama, are pristine high-altitude Andean lakes found along the central Andes of South America. This shallow ecosystem suffers from permanent evaporation, leading to falling water levels, causing it to recede or disappear during the dry season. This dynamic causes physicochemical changes in lakes, such as low nutrient availability, pH change, and dissolved metals, which can influence the composition of the microbial community. In this study, we used a metataxonomic approach (16S rRNA hypervariable regions V3 to V4) to characterize the sedimentary microbiota of these lakes. To understand how the water column affects and is structured in the microbiota of these lakes, we combined the analysis of the persistence of the water column through satellite images and physicochemical characterization. Our results show a significant difference in abiotic factors and microbiota composition between La Punta and La Brava lakes. In addition, microbiota analysis revealed compositional changes in the ecological disaggregation (main and isolated bodies) and antagonistic changes in the abundance of certain taxa between lakes. These findings are an invaluable resource for understanding the microbiological diversity of high Andean lakes using a multidisciplinary approach that evaluates the microbiota behavior in response to abiotic factors. IMPORTANCE In this study, we analyzed the persistence of the water column through satellite images and physicochemical characterization to investigate the composition and diversity in High Andean Lake Systems in a hyperarid environment. In addition to the persistence of the water column, this approach can be used to analyze changes in the morphology of saline accumulations and persistence of snow or ice; for example, for establishing variable plant cover over time and evaluating the microbiota associated with soils with seasonal changes in plants. This makes it an ideal approach to search for novel extremophilic microorganisms with unique properties. In our case, it was used to study microorganisms capable of resisting desiccation and water restriction for a considerable period and adapting to survive in ecological niches, such as those with high UV irradiation, extreme drought, and high salt concentration.

Copyright of Revista Austral de Ciencias Sociales is the property of Facultad de Filosofia y Humanidades, Intituto de Ciencias Sociales, Universidad Austral de Chile and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The land snail Megalobulimus spp. has been frequently recorded in prehispanic cemeteries in the oases of San Pedro de Atacama, Chile, despite the fact that it is not native to this region. It lives in the humid and tropical environment of northwestern Argentina, for which reason, when it is found outside its native habitat, its presence is taken as an indicator of long-distance exchange. Archaeologists posit that its function was to hold color pigments. In this multidisciplinary study we analyze the snail's presence in funerary contexts, complementing this with a taxonomic analysis of archaeological specimens and a review of biological-ethological data of said gastropod. We present unpublished data regarding the use of Megalobulimus in the Atacama, while providing new information about its connection to the practice of inhaling psychoactive substances. We conclude that its function as a container of pigments, carbonates, or hallucinogens stems from its symbolic meaning as part of the vital renewal through the fertilizing water of the earth. This symbolism explains the role that Megalobulimus played in the ritual exchange networks of the Circumpuneña area and, by extension, the Central-South Andes. [ABSTRACT FROM AUTHOR]

Substantial knowledge has accumulated on the microbiome of the hyperarid Atacama Desert during the last two decades; however, information on Atacama free-living amoebae (FLA) is limited and increasing efforts are required. FLA are polyphyletic heterotrophic naked or testate protists that feed on organic matter, fungi, protozoa, and bacteria and may disseminate infections. Amoebae in Chile are represented by 416 taxa and 64 genera, and 29 taxa have been identified in arid shrub lands at the southern limit of the Atacama Desert, and Acanthamoeba are present in all the country's regions. To expand our knowledge and to contribute to the biogeographic distribution of Atacama FLA, we report the dominant presence of members of the genus Acanthamoeba in water and sediment sampled at the Loa and Salado rivers in the pre-Andean zone of the Antofagasta Region, northern Chile, at sites 2500 m above sea level. We expect these observations and preliminary evidence of FLA presence in other wetlands (Chiuchiu, Tebenquiche) in this region to be incentive for further exploration of Atacama amoebae. [ABSTRACT FROM AUTHOR]

The Salar de Atacama in northern Chile hosts the biggest lithium reserves globally. However, concerns have arisen regarding the environmental impact of lithium extraction on its basin; in particular, the possible drought of its lagoons that sustain unique natural ecosystems. This investigation implemented an image processing and statistical methodology to assess the area evolution and dynamic behavior of these main water bodies between 1986 and 2018. Results showed that these lagoon systems have not presented significant changes despite increasing lithium production, even for the years of large brine extraction. The analysis indicated that the total surface area of the lagoons varied within a restricted range at 95% confidence level: on average, of the total area covered by these systems 0.03% could have been lost or 0.01% could have been gained per year. Moreover, a multivariate analysis indicated that brine extraction did not have a negative impact on the evolution of the surface areas of the lagoons during the last three decades. [ABSTRACT FROM AUTHOR]

ABSTRACT Salar de Atacama is located approximately 55 km south of San Pedro de Atacama in the Antofagasta region, Chile. The high UV irradiation and salt concentration and extreme drought make Salar de Atacama an ideal site to search for novel soil microorganisms with unique properties. Here, we used a metataxonomic approach (16S rRNA V3-V4) to identify and characterize the soil microbiota associated with different surface azonal vegetation formations, including strict hygrophiles (Baccharis juncea, Juncus balticus, and Schoenoplectus americanus), transitional hygrophiles (Distichlis spicata, Lycium humile, and Tessaria absinthioides), and their various combinations. We detected compositional differences among the soil surface microbiota associated with each plant formation in the sampling area. There were changes in soil microbial phylogenetic diversity from the strict to the transitional hygrophiles. Moreover, we found alterations in the abundance of bacterial phyla and genera. Halobacteriota and Actinobacteriota might have facilitated water uptake by the transitional hygrophiles. Our findings helped to elucidate the microbiota of Salar de Atacama and associate them with the strict and transitional hygrophiles indigenous to the region. These findings could be highly relevant to future research on the symbiotic relationships between microbiota and salt-tolerant plants in the face of climate change-induced desertification. IMPORTANCE The study of the composition and diversity of the wetland soil microbiota associated with hygrophilous plants in a desert ecosystem of the high Puna in northern Chile makes it an ideal approach to search for novel extremophilic microorganisms with unique properties. These microorganisms are adapted to survive in ecological niches, such as those with high UV irradiation, extreme drought, and high salt concentration; they can be applied in various fields, such as biotechnology and astrobiology, and industries, including the pharmaceutical, food, agricultural, biofuel, cosmetic, and textile industries. These microorganisms can also be used for ecological conservation and restoration. Extreme ecosystems are a unique biological resource and biodiversity hot spots that play a crucial role in maintaining environmental sustainability. The findings could be highly relevant to future research on the symbiotic relationships between microbiota and extreme-environment-tolerant plants in the face of climate change-induced desertification.

Understanding groundwater flow involves characterizing the spatial variability of aquifer attributes and possible hydraulic connectivity structures. The latter are of crucial importance because high permeability channels may control groundwater flow and contaminant transport. In evaporitic aquifer systems, these preferential channels can consist of karst conduits, developed at different scales, as well as fault zones. These features condition the economic development of salt flats at the Central Andes. Hydraulic connectivity may affect exploitation efficiency by enhancing the inflow of less evaporated brine thus diminishing its mineral content (i.e., concentration of Li and K). In this context, we investigate if it is possible to use (tomographic) stochastic inversion (regularized pilot point method) in order to characterize the presence of connectivity structures in an evaporitic aquifer of great extension (some 1,500 km2) from head response measured at numerous observation points during a year long sequence of three hydraulic tests. Results show that, even though the solution is nonunique, the main preferential flow zones are identified. Numerous inversions yield similar fits to observed drawdowns with maximum errors of few centimeters. Preferential flow is identified not only by elongated high permeability regions, but also by a marked scale effect (model transmissivities are some 30 times larger than their local tests counterparts). The main high conductivity zones are consistent with independent information based on geophysics, isotopes, mixing ratios, piezometric data, and the expected dissolution processes. Key Points: A hydraulic test is carried out and monitored in many observation points to assess heterogeneity over a tens of kilometers karst aquiferStochastic inversion allows us to identify preferential flow paths, which are consistent with independent dataA marked scale effect is observed, suggesting that karst structures control large scale permeability [ABSTRACT FROM AUTHOR]

The need of establishing more substantive dialogs between the mainstream and Indigenous knowledge on volcanoes has been increasingly recognized. To contribute to this endeavor, in this article we present the basic volcanological understandings of the Lickanantay people in the Salar de Atacama Basin. The Salar de Atacama Basin is an active volcanic territory within the Central Volcanic Zone of the Andes (CVZA). From the El Tatio geothermal field to Socompa volcano, more than 19 active volcanoes surround the territory that the Lickanantay (Atacameño) people have inhabited for more than 11,000 years. Living around and with the geological dynamism of the CVZA for millennia, the Lickanantay communities have accumulated rich observational and ceremonial data on volcanoes and volcanism. Paradoxically, however, while the Atacameño people have thoroughly characterized the CVZA, the volcanology community has not been properly introduced to the ancestral knowledge articulated in the territory. In order to make traditional Atacameño perspectives on volcanoes, volcanic risk, and geo-cosmic interdependence more amply available to the volcanology community, in this article, we present a basic description of what we call Atacameño volcanology. By Atacameño volcanology, we understand the ancestral principles by which volcanoes are known and understood as partaking in larger processes of a cosmo-ecological formation. Specifically, we describe the basic volcanological notions arising from the Lickanantay ancestral knowledge—volcanic formation, functions, and behavior. Second, we focus on the El Tatio geothermal field to offer a situated example. Finally, we delineate some relevant elements of human–volcano interactions and volcanic risk management from an Atacameño perspective. In our conclusions we suggest that volcanology, particularly in the context of the Andes, needs to engage more substantially with the Atacameño or other ancestral systems of knowledge production to expand volcanological insights and respond to the call for decolonizing science.

Godofredo Enes Pereira, Christina Leigh Geros and Jon Goodbun have been analysing governmental Green New Deal policy globally, viewing it through the microcosmic eye of their own research and that of their students on the MA Environmental Architecture course at the Royal College of Art in London. This includes their Lithium Triangle project that concentrates on the environmental damage caused by the extraction of lithium from the Chilean landscape, and the Orang‐orang and the Hutan project in Indonesia that contests Western dominance and the effects of centuries of colonisation. [ABSTRACT FROM AUTHOR]

In this article, the contents of the niche-chambers situated within the perimeter wall of the Early Formative temple Tulán-54, located in the south-east of the Circumpuna Atacameña, are described and analyzed. The identification of animal bones, remains of lithic debris, of copper ore and ceramic fragments, as well as the burial of an adult, a metate offering and an entire Tilocalar-Los Morros type vessel, dated to 2640 BP (2765 to 2715 cal BP), indicate a relationship with the temple founding events. An infant burial found inside a sealed chamber of the ceremonial architecture was dated to 2600 BP (2750 to 2700 / 2630 to 2620 / 2560 to 2540 cal. BP), a period synchronous with the use of the niches. The nature and dating of the associated contexts are discussed in general and we reach the conclusion that the evidence found in the niches-chambers was part of the early performance practices of the temple.

In arid and semiarid regions, persistent hydrological imbalances illuminate the considerable gaps in our spatiotemporal understanding of fundamental catchment‐scale governing mechanisms. The Salar de Atacama basin is the most extreme example of groundwater‐dominated continental basins and therefore is an ideal place to probe these unresolved questions. Geochemical and hydrophysical observations indicate that groundwaters discharging into the basin reflect a large regional system integrated over 102–104 year timescales. The groundwater here, as in other arid regions, is a critical freshwater resource subject to substantial demand from competing interests, particularly as development of its world‐class lithium brine deposit expands. Utilizing a uniquely large and comprehensive set of H and O isotopes in water, we demonstrate that much of the presumed recharge area on the Altiplano‐Puna plateau exhibits isotopic signatures quite distinct from waters presently discharging within the endorheic Salar de Atacama watershed. δ18O values of predicted inflow source waters are 3.6‰ to 5.6‰ higher than modern plateau waters, and 3H data from 87 discrete samples indicate that nearly all of this inflow is composed of premodern recharge (i.e., fossil water). Under plausible conditions, these distinctions cannot be explained solely by natural variability in modern meteoric inputs or by steady state groundwater flow. We present a conceptual model revealing the extensive influence of transient draining of fossil groundwater storage augmented by regional interbasin flow from the Andes. Our analysis provides robust constraints on fundamental mechanisms governing this arid continental groundwater system and a framework within which to address persistent uncertainties in similar systems worldwide. Plain Language Summary: Groundwater in the driest places on Earth is a vital resource for both humans and ecosystems, yet fundamental characteristics of this water such as where it originates and how it moves in the ground remain unresolved. This water often lies deep underground and flows across great distances and over long periods of time; as a result, it is quite difficult to study. Using the 1,000 water samples in the Salar de Atacama basin in northern Chile at the border of the driest desert on Earth, we trace the origin and traveltime of water across a large region. Groundwater in the Salar de Atacama region is fundamental to sustaining natural and human systems; therefore, developing a better understanding of how this water moves will be critical for their management, particularly as development of its world‐class lithium brine deposit expands. We find that "fossil water," which entered the ground hundreds or thousands of years ago, makes up most of the water now flowing into the basin. Our analysis also defines the area that contributes water to the basin, much of which incorporates flow through mountains and from other higher‐elevation basins. By improving our understanding of how these large flow systems develop and function, this work will aid efforts to sustainably manage these critical freshwater resources for all who rely on them. Key Points: Analysis of tritium in water discharging within Salar de Atacama basin shows that it is composed predominantly of water >60 years oldWater entering the Salar de Atacama basin is spatially distinct and decoupled from recharge on the Altiplano‐Puna plateauAnalysis of stable O and H isotope ratios in 900 water samples constrains the spatiotemporal dimensions of modern and fossil groundwaters [ABSTRACT FROM AUTHOR]

The late Mesozoic-Cenozoic evolution of the Central Andes of northern Chile consists of a series of events related to changing conditions along the plate margin, leading to different episodes of compression and extension. A long-lasting basin which records these changes corresponds to the Salar de Atacama Basin. Its tectonic history has been blurred by several interpretations of seismic reflection lines and multiple chronostratigraphic correlations between subsurface-surface units. As such, many aspects of its tectonic evolution are still unclear. In this study, we performed an E-W gravimetric profile across the Barros Arana Syncline and the basin. We analyzed interval velocities obtained from seismic reflection studies and reviewed the profiles closest to the gravity survey. Four U-Pb samples for detrital zircon analysis were obtained from Late Cretaceous-Paleogene units. Geophysical data show a segmentation of physical properties within the basin, with denser units and faster interval velocities around the late Mesozoic-early Cenozoic units, and lighter, slower units in the actual salt pan. The main contrast in physical properties is observed in the evaporitic and fine-grained continental deposits of the San Pedro Formation. Geophysical and geological constraints show that its thickness varies between 800 and 1200 m, and that it was deformed during later events. The U-Pb data show that the rocks within the Barros Arana Syncline reach well into the Paleogene, and that they were mainly deformed during the late Eocene Incaic Event, where an east-verging thrust system also involving Permo-Triassic units was developed, establishing the actual structural configuration. The late Oligocene-early Miocene units were then deposited in a post-orogenic setting, with minor compression. A stronger phase around the late Miocene reactivated previous structures and folded these deposits. This continuous, compressive history of the basin, which is mostly a result of the Incaic Event, is in agreement with the regional evolution of the Central Andes. • New geophysical and geological data were obtained from the Salar de Atacama Basin. • A distinct geophysical contrast is found between the various geological units. • The area was mainly deformed during the Incaic Event. • New ages show a long-lasting sedimentation within Cretaceous-Paleogene successions. • Compression seems to have been dominant over the last 100 Ma. [ABSTRACT FROM AUTHOR]

Spatiotemporal patterns of deformation and exhumation in the central Andes are key parameters for reconstructing the kinematic history of the orogenic belt. Previous studies of the retroarc thrust belt document overall eastward propagation of deformation since the late Eocene, but the amount and timing of exhumation during the early phase of Andean orogeny remains largely unconstrained, particularly in the modern forearc region. In order to determine the timing and amount of exhumation prior to the late Eocene, we employed a multidating approach combining zircon U‐Pb geochronology with apatite fission track and apatite (U‐Th)/He thermochronology. We focus on the low‐temperature cooling history of the Cordillera de Domeyko thrust belt and synorogenic deposits in the Salar de Atacama basin. Our results show Late Cretaceous to Oligocene cooling and exhumation in the Cordillera de Domeyko. The distribution of cooling ages in the forearc indicates three periods of exhumation: ~86–65, ~65–50, and 50–28 Ma. The amount of cooling was variable in space and time but requires total exhumation of ~2.5–3.3 km of rocks above major structures in the thrust belt. Regional unconformities in the Salar de Atacama basin correlate with periods of eastward migration of the orogenic front at ~65 Ma and ~50–40 Ma. Pulses of deformation at the front of the thrust belt alternated with periods of out‐of‐sequence hinterland deformation and exhumation. Overall, our data show that shortening in the central Andes commenced during the Late Cretaceous (as early as ~86 Ma) and that deformation (shortening) and exhumation were coupled in space and time. Key Points: The Cordillera de Domeyko experienced exhumation during the upper Cretaceous, Paleocene, Eocene, and OligoceneThe Cordillera de Domeyko experienced ~2.5‐3.3 km of exhumation above major structuresRegional unconformities in the Salar de Atacama basin correspond to periods of migration of the orogenic front at ~65 and between 40 and 50 Ma [ABSTRACT FROM AUTHOR]

Through the case study of the Salar de Atacama, Chile, this work explores how environmental protection can go beyond conservation to become an opportunity and tool to resize the scale and presence of the extractive practices on the land. The study proposes to define a model of 'protection' for this region that transcend the anthropocentric models of environmental protection born in the Western world. It designs the political space and a series of protocols that allow the shift from protection to environmental care, which is inclusive of ways of living of the indigenous population, expanded cross species kinship and extra human living beings united in life around the Salar de Atacama. [ABSTRACT FROM AUTHOR]

Salar de Atacama is one of the largest global reservoirs of natural lithium brines (mean lithium concentration = 1,500 ppm), enabling Chile to be a leading producer of lithium products. This large salar (3,000 km2), located in the Atacama Desert at 2,300 m above sea level, is dominated by microorganisms; however, little is known about the microbes present in the brines associated with this economically important mining process. Here we study lithium as a modulator of microbial richness and diversity in brines representing natural conditions (34.7% salinity) and conditions prior to lithium production with a concentrated brine (55.6% salinity). Brines only supported a single archaeal family (Halobacteriaceae): natural brines included the archaeal genera Halovenus, Natronomonas, Haloarcula, and Halobacterium. Concentrated brines included the archaeal genera Halovenus, Halobacterium, and Halococcus. The most abundant bacterial families in natural brine were Rhodothermaceae and Staphylococcaceae; Xanthomonadaceae dominated the bacterial community in the concentrated brine. A comparison of entire microbial community (Archaea and Bacteria) revealed that only seven operational taxonomic units were shared between samples, all of which were Archaea. Further, our results showed that Bacteria were phylogenetically more diverse and rich in the concentrated brine, while archaeal diversity was maximized in the natural brine. The concentrated lithium brines of the Salar de Atacama represent one of the most saline environments described to date (dominated by LiCl). We suggest that elevated concentrations of lithium could greatly modulate microbial diversity and give insights into the adaptive biology of microorganisms required to cope with extremely high concentrations of salts that extend beyond that of NaCl, a far more commonly studied salt. Plain Language Summary: Lithium is a main component of many of the batteries that we rely on for our daily use. In the last years, nearly 40% of all lithium obtained globally was from a single fragile salt‐lake ecosystem: Salar de Atacama in the Atacama Desert of northern Chile. This salar has extremely saline waters called brines (dominated by NaCl, aka table salt), which are naturally highly concentrated in lithium and concentrated in evaporation ponds. In total, concentrated brines has a salinity of 55.6% (ocean salinity = 0.3%), representing one of the most saline environments described on Earth to date (dominated by lithium chloride). Our research has shown that concentrated brines support life and are dominated by hundreds of species of microorganisms. Due to saline stress these "extremophiles" have developed very special (and previously undescribed) strategies to survive in this lithium soup. These results have implications beyond Earth: they have marked implications for our understanding for the potential for life on Mars, where liquid water is known to occur as brine. Although lithium production has clear economic importance, our results show that we should consider how we will preserve these unusual ecosystems that act as reservoirs of unique microbial life. Key Points: The microbial diversity of brines from Salar de Atacama differs according to the concentration of lithiumThe brines with low lithium concentrations were dominated by Archaea, and Bacteria dominated lithium‐ concentrated brinesOur research revealed the presence of microbial life in one of the most saline environments that has been described on Earth [ABSTRACT FROM AUTHOR]

Abstract The Salar de Atacama basin is the main topographic low of the Preandean Depression of the Central Andes of northern Chile. Although numerous studies have been carried out in this area, the origin of the depression is still a matter of debate. The integration of seismic reflection and surface structural data along the basin allows the characterization of Oligocene and Neogene tectonic activity of the Salar de Atacama. A key element to unravel the Neogene to recent history of the basin is found along the Cordillera de la Sal, which comprises more than 3000 m of continental sedimentary succession assigned to the San Pedro Formation. Detailed analysis of the seismic data shows that large depocenters involving distal alluvial facies and evaporitic members of the San Pedro Formation accumulated in close relation with Oligocene extension. Extension was controlled by a first order normal fault located along the western flank of the Atacama basin, which appears as a key structural feature of the internal architecture of the Salar de Atacama. The rise of the Cordillera de la Sal ridge during the Neogene involved compression and sinistral strike slip in its southern domain, in combination with salt diapirism in its north domain. This transition is related to the thickness and distribution of the evaporitic lower members of the San Pedro Formation, which also controls the depth of the detachment level beneath the Cordillera de la Sal. Our results show that the current relief of the Salar de Atacama basin is mainly due to Oligocene extension and subsequent Neogene tectonic inversion. Highlights • A new structural model for the Oligocene-Neogene development of the Salar de Atacama basin. • The Oligocene extension was controlled by a main master fault beneath the western border of the basin. • The contrast in the Neogene deformation mechanisms that uplifted the Cordillera de la Sal relies on the previous basin fill. [ABSTRACT FROM AUTHOR]

The accumulation of solutes delivered via shallow groundwater and surface water in arid to hyper-arid closed basins, and the complex hydrogeochemical processes associated with their transport, are key to deciphering mechanisms responsible for the formation of brines and salts in these environments. A rigorous investigation of the hydrogeochemical fluxes and the formation of the Li-enriched brine in the hyper-arid basin of the Salar de Atacama, Chile is presented. Water fluxes within the Salar de Atacama basin range from 0.003 m 3 /s to 1.50 m 3 /s with a poor correlation between discharge and drainage basin area. The inflowing waters have major elemental and Li concentrations that are within the same order of magnitude over a period of several decades. The element fluxes indicate, for example, that 58% of the Li in the halite nucleus and brines is derived from the south and southeast parts of the basin. The average δ 18 O vsmow and δD vsmow of inflow waters indicate that there are varied sources of recharge corresponding to the defined sub watershed regions. The average water flux-weighted 87 Sr/ 86 Sr of inflow waters allows further definition of where in the regional watershed the solutes are derived. The predicted water flux weighted 87 Sr/ 86 Sr of the brines (0.70813) compared to the measured average 87 Sr/ 86 Sr (0.70801), indicates that there may be unaccounted sources of water and solutes to the basin brines. Elemental accumulation time scales for the volume of halite and brine in the nucleus balance on time frames of 0.5 Ma (Mg), 1.0 Ma (Ca), 1.9 Ma (Li) and 2.2 Ma (K) as compared to 47 Ma (Na) and 53 Ma (Cl), further evidence that Na and Cl require additional sources not accounted for in the modern inflows to the topographic watershed. Dissolved noble gas concentrations of marginal and nucleus brines specify that the brines formed in an atmospheric equilibrated state and have since been isolated below the salt crust. A process-based model is presented to explain the extremely high concentrations of Li in brines which incorporates the δ 7 Li isotope signatures of waters in the basin to further decipher, on a first order, the contributions of processes such as low temperature weathering and secondary phase formation. [ABSTRACT FROM AUTHOR]

Birds often participate in mixed-species foraging associations to improve their feeding efficiency. Wilson's Phalaropes Steganopus tricolor wintering in saline lakes of the Atacama Desert, northern Chile, were found to feed either solitarily or in close proximity (commensally) to Chilean Flamingos Phoenicopterus chilensis. Those individuals following Chilean Flamingos were picking up prey (mainly copepods) stirred up by flamingos rapidly stomping their feet ('foot paddling'). In contrast, Wilson's Phalaropes ignored Andean Flamingos Phoenicoparrus andinus and Chilean Flamingos using different foraging tactics. Feeding rates of Wilson's Phalaropes associating with Chilean Flamingos (38 ± 9 prey/min) were significantly higher than those of solitary phalaropes (17 ± 6 prey/min), indicating that this association allows profitable feeding on small prey suspended in water. Although this association appears to involve a high benefit to Wilson's Phalaropes and a low cost (if any) to Chilean Flamingos, thus partly explaining the stability of mixed-species groups, it is restricted to moderate and deep foraging depths. Three other shorebird species (Baird's Sandpiper Calidris bairdii, Lesser Yellowlegs Tringa flavipes and Greater Yellowlegs Tringa mela - noleuca) associated with the Chilean Flamingo at shallower foraging depths, indicating these facilitative interactions are species and context dependent. [ABSTRACT FROM AUTHOR]

With the aim of establishing a theory of industrialization policy for natural resources, this studyidentifies the determinants of Chilean industrialization policy, focusing on the following: 1) natural resources in general, and 2) lithium in particular. Having identified these determinants, the three variables under consideration are the political, economic and strategic values of lithium. In essence, the study argues that the combination of medium political value, medium economic value and the low strategic value of lithium have led the Chilean state to maintain lithium in the “strategic mineral” status, as a means to sustain current lithium development contracts with private companies, to affirm state ownership of existing mineral resources and to introduce public-private partnerships for the future development of lithium as a resource in Chile. [ABSTRACT FROM AUTHOR]

The lacustrine systems of La Brava and La Punta, located in the Tilopozo sector in the extreme south of Salar de Atacama, are pristine high-altitude Andean lakes found along the central Andes of South America. This shallow ecosystem suffers from permanent evaporation, leading to falling water levels, causing it to recede or disappear during the dry season. This dynamic causes physicochemical changes in lakes, such as low nutrient availability, pH change, and dissolved metals, which can influence the composition of the microbial community. In this study, we used a metataxonomic approach (16S rRNA hypervariable regions V3 to V4) to characterize the sedimentary microbiota of these lakes. To understand how the water column affects and is structured in the microbiota of these lakes, we combined the analysis of the persistence of the water column through satellite images and physicochemical characterization. Our results show a significant difference in abiotic factors and microbiota composition between La Punta and La Brava lakes. In addition, microbiota analysis revealed compositional changes in the ecological disaggregation (main and isolated bodies) and antagonistic changes in the abundance of certain taxa between lakes. These findings are an invaluable resource for understanding the microbiological diversity of high Andean lakes using a multidisciplinary approach that evaluates the microbiota behavior in response to abiotic factors. IMPORTANCE In this study, we analyzed the persistence of the water column through satellite images and physicochemical characterization to investigate the composition and diversity in High Andean Lake Systems in a hyperarid environment. In addition to the persistence of the water column, this approach can be used to analyze changes in the morphology of saline accumulations and persistence of snow or ice; for example, for establishing variable plant cover over time and evaluating the microbiota associated with soils with seasonal changes in plants. This makes it an ideal approach to search for novel extremophilic microorganisms with unique properties. In our case, it was used to study microorganisms capable of resisting desiccation and water restriction for a considerable period and adapting to survive in ecological niches, such as those with high UV irradiation, extreme drought, and high salt concentration., Competing Interests: The authors declare no conflict of interest.

We document, analyse, and interpret direct and rapid infiltration of precipitation to the southern margin of the Salar de Atacama halite-hosted brine aquifer during two intense precipitation events in 2012-2013. We present physical, geochemical, and stable and radioactive isotope data to detail this influx of water. The two events differ distinctly in the mechanisms of recharge. The 2012 event did not produce direct precipitation onto the salar surface, while the 2013 event did. Both events are recorded by abrupt changes in head in observation wells along the halite aquifer margin. Spatially distributed water levels rose by over 30 cm during the larger 2013 event consistent with remotely sensed observations of surface water extent. The lithium concentration and stable isotopic composition of water indicate dilution of brine and dissolution of salt with fresh water. Tritium measurements of precipitation, surface water, and groundwater all indicate modern influx of water to the halite aquifer along the southern margin. We extend these observations by examining the response of the halite aquifer as a whole to precipitation events during the period of 2000-2010. This study suggests that local recharge to the aquifer during sporadic precipitation onto the halite nucleus is an important component of the modern water budget in this hyper-arid environment. The rapid dissolution and salinization along the southern margin of the salar halite nucleus are aided by such precipitation events contributing a modern fresh water component to the water budget of the economically valuable lithium-rich brine. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Wormholes are highly conductive channels that develop in high solubility rocks. They are especially important for environmental and industrial sustainability in saline karst aquifers (e.g. Salar de Uyuni, Salar de Atacama). Wormholes dynamics (i.e., the space and time evolution of these preferential flow paths) depends on the hydrodynamic and geochemical conditions during formation, as well as on wormholes competition for flow. Despite the importance of wormholes interaction for their development, experimental efforts have focused on the evolution of a single flow-path. Direct observation and quantification of wormholes dynamics is still lacking. We propose an experimental set-up to visualize and characterize the dynamics of multiple wormholes, which may help to understand the changes in flow and transport behaviour of aquifers. We performed a dissolution experiment in a 2D synthetic evaporitic aquifer, and simultaneous fluorescent tracer tests before and during wormhole growth. We visualized the growth by sequential photographs, with the fluorescent tracer highlighting the evolving structures. We quantified wormholes dynamics by measuring pressure and mass changes of the aquifer, and by image analysis. On the one hand, results show that wormholes tend to form along areas where flux was fastest prior to dissolution. They also show clear evidence of competition for water between wormholes and represent the first quantitative evidence of the amplifying factor that drives the self-organization in wormhole growth. On the other hand, we found that the competition is slower than predicted by current analytical and numerical theories, but consistent with other laboratory results. We conjecture that the discrepancy between theory and experiments can be attributed to the combined effect of non-linear kinetics and particle dragging during dissolution. We then compared experimental tracer breakthrough curves before and during the formation of preferential flow paths. They reflect wormhole growth by an accentuated non-Fickian behaviour, with reduced first arrival and increased tailing., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Daniel Fernandez Garcia reports financial support was provided by SQM SA., (Copyright © 2022. Published by Elsevier B.V.)

The Atacama region in Northern Chile hosts the driest desert on Earth and provides the second highest global Li production, containing the largest reported lithium reserves in the world. The occurrence of extremely elevated Li concentration is restricted to brine deposits contained in the halite nucleus of the Salar de Atacama (SDA). The origin of Li and other solutes in the Andean salt flats has been attributed to different processes, where weathering of Neogene and Quaternary volcanic rocks has been considered to be the most important. Despite recent advances, there is still limited geochemical and isotopic Li data in ignimbrites, particularly surrounding the SDA, hence the potential of these units as a source has remained elusive. In this study, we provide new Li concentration and isotopic data in ignimbrites from the Western Cordillera, fine sediments from the marginal zone of the SDA, and suspended load in shallow groundwater. A moderate enrichment (between 20 and 50 ppm) is recorded in volcanic rocks, averaging 33 ppm, while fine sediments present Li contents one order of magnitude higher, with a mean concentration of ~290 ppm. Due to the Li contents recorded in ignimbrites, which is slightly higher than the upper crust average (24–30 ppm; Rudnick and Gao, 2004), we propose that the potential of these units as the main source of Li resides in their large areal extent, volume, and hydraulic gradient with respect to the SDA. The δ7Li values in ignimbrites vary from −1.5 ‰ to +12.8 ‰. In contrast, marginal zone sediments show negative values of δ7Li (from −1.9 ‰ to −5.3 ‰), except for fine sediments from the Peine Block where a δ7Li is +4.4 ‰. Our results reveal that the measured δ7Li in ignimbrites would indicate volatile exsolution as the main syn -eruptive factor controlling the isotope Li distribution. Regarding post-eruptive processes, water-rock interactions trigger partition of 7Li from ignimbrite to water. Both syn -eruptive and post-eruptive proposed were tested by numerical modeling, supporting our interpretation. We propose that the predominant constituent in ignimbrites, crystals or glass, impacts the subsequent distribution and fractionation of Li in inflowing waters and fine sediments covering the marginal zone. The analysis presented here allows us to define three subzones where different processes are controlling Li fractionation. These factors together with the geological, hydrologic, and climatic history of the region have led to the world-renowned accumulation of Li in the SDA. [Display omitted] • The potential of ignimbrites as a source of Li resides in their volume and key location. • The δ7Li values in ignimbrites surrounding the SDA range between −1.5 ‰ and +12.8 ‰. • The crystallinity degree in ignimbrites impacts the Li distribution and isotopic fractionation. • Based on geochemical and isotopic Li distribution, the SDA can be divided in three subzones. [ABSTRACT FROM AUTHOR]

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Copyright of Estudios Atacameños is the property of Estudios Atacamenos and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

During Li recovery from salar brines, Li concentration is typically increased to about 60,000 mg L−1 by evaporation. We investigated the concentration changes of Li, Na, K, Mg, Cl, SO4, and B during evaporation of both natural Uyuni and artificial Atacama brines. The Uyuni brine exhibited a maximum Li concentration of 6810 mg L−1 at 31 days of evaporation, at which point the majority of the Na and K in the brine was removed. The Li concentration decreased with further evaporation due to precipitation as Li2SO4, such that the level at the 56 day mark was approximately 4130 mg L−1. In contrast, the artificial Atacama brine showed no pronounced Li precipitation, even after 54 days, at which point the Li concentration was 21,800 mg L−1. The initial concentrations of Na and K in the Atacama brine were higher than those in the Uyuni brine, and the Atacama solution still retained K after 54 days of evaporation. The order of precipitation of cation species during the evaporation of both brines was: Na, followed by K, Mg, and Li. Thus, Li precipitation in the Atacama brine might be prevented due to the more favored precipitations of Na and K, such that significant Li removal did not occur in this brine. [ABSTRACT FROM AUTHOR]

The Salar de Atacama is located in the most arid desert in the world. Despite its extreme conditions, it has many ecosystems of high ecological value. The Soncor ecosystem, a sequence of lagoons, is the most important environment of the region as it acts as the centre for the breeding of the Andean Flamingo. This salt flat also contains significant mining deposits and is an important water source for the region. Freshwater and brine—enriched in lithium and potassium—are being pumped from the aquifers near to the Soncor ecosystem, which has so far not been greatly affected by this groundwater extraction. However, there is a potential risk that future anthropogenic effects may disturb this fragile environment. The objective of this study is to determine the origin of the water sources of the Soncor ecosystem so as to adequately manage its water resources. Three hypotheses previously proposed in the technical literature were investigated in order to determine proactive actions to protect this fragile ecosystem. The study utilized classic hydrogeological techniques, such as the construction of stratigraphic profiles, piezometric maps and stream gauging, combined with less-common isotopic techniques, such as the87Sr/86Sr ratio. The results confirmed the hypothesis that the origins of the water sources are associated with groundwater inputs coming from the east side of the salt flat, in the north of the basin. EditorZ.W. Kundzewicz;Associate editorM. Acreman CitationOrtiz, C., Aravena, R., Briones, E., Suárez, F., Tore, C., and Muñoz, J.F., 2014. Sources of surface water for the Soncor ecosystem, Salar de Atacama basin, northern Chile.Hydrological Sciences Journal, 59 (2), 336–350. [ABSTRACT FROM PUBLISHER]

Salar de Atacama is located approximately 55 km south of San Pedro de Atacama in the Antofagasta region, Chile. The high UV irradiation and salt concentration and extreme drought make Salar de Atacama an ideal site to search for novel soil microorganisms with unique properties. Here, we used a metataxonomic approach (16S rRNA V3-V4) to identify and characterize the soil microbiota associated with different surface azonal vegetation formations, including strict hygrophiles (Baccharis juncea, Juncus balticus, and Schoenoplectus americanus), transitional hygrophiles (Distichlis spicata, Lycium humile, and Tessaria absinthioides), and their various combinations. We detected compositional differences among the soil surface microbiota associated with each plant formation in the sampling area. There were changes in soil microbial phylogenetic diversity from the strict to the transitional hygrophiles. Moreover, we found alterations in the abundance of bacterial phyla and genera. Halobacteriota and Actinobacteriota might have facilitated water uptake by the transitional hygrophiles. Our findings helped to elucidate the microbiota of Salar de Atacama and associate them with the strict and transitional hygrophiles indigenous to the region. These findings could be highly relevant to future research on the symbiotic relationships between microbiota and salt-tolerant plants in the face of climate change-induced desertification. IMPORTANCE The study of the composition and diversity of the wetland soil microbiota associated with hygrophilous plants in a desert ecosystem of the high Puna in northern Chile makes it an ideal approach to search for novel extremophilic microorganisms with unique properties. These microorganisms are adapted to survive in ecological niches, such as those with high UV irradiation, extreme drought, and high salt concentration; they can be applied in various fields, such as biotechnology and astrobiology, and industries, including the pharmaceutical, food, agricultural, biofuel, cosmetic, and textile industries. These microorganisms can also be used for ecological conservation and restoration. Extreme ecosystems are a unique biological resource and biodiversity hot spots that play a crucial role in maintaining environmental sustainability. The findings could be highly relevant to future research on the symbiotic relationships between microbiota and extreme-environment-tolerant plants in the face of climate change-induced desertification.

Highlights: [•] A mineral zoning due to geochemical processes was investigated in the study zone. [•] A groundwater flow model was built considering precipitation/dissolution reactions. [•] Precipitation/dissolution reactions altered the aquifer’s physical properties. [•] Model results reproduced well the mineral zoning in the Atacama salt flat aquifer. [•] Geochemical processes modified groundwater flow in the Atacama salt flat aquifer. [ABSTRACT FROM AUTHOR]

The Salar de Atacama, located in Northern Chile, is a wide salt flat that is characterized by several salt lakes, which are locally called lagunas. The Laguna de la Piedra is one of the salt lake systems that is located in the northernmost sector of the Salar de Atacama. The present paper examines some physicochemical properties of the Laguna de la Piedra as well as the microbial diversity of the evaporite deposits. Under extreme desiccation and ambient UV flux, the evaporite deposits can create favorable endolithic microniches for the development of microorganisms. In the Laguna de la Piedra these deposits host a variety of halophilic microorganisms, which were investigated by using an optical and environmental scanning electron microscope (ESEM) as well as molecular diversity studies based on the small subunit ribosomal (SSU) rRNA of Bacteria, Archaea and Eucarya. We detected a single phylotype of halophilic archaea and a oxytrichid ciliate. Within the bacteria, a variety of Cyanobacteria, Bacteroidetes, Alpha-, Beta- and Deltaproteobacteria, as well as members of the candidate division TM6, were identified. [ABSTRACT FROM AUTHOR]