Puna Region Research Articles

Crustal bobbing in response to lithospheric foundering recorded by detrital proxy records from the central Andean Plateau

Lithospheric foundering is an important mechanism of crustal deformation and recycling, basin subsidence, and surface uplift in orogenic systems. The Arizaro Basin, in the Puna region of NW Argentina, is a place where foundering was proposed to have taken place during the late Miocene. The Arizaro Basin has been described as a “bobber” basin produced by Miocene lithospheric foundering. The geometry, sedimentology, deformation, and paleoelevation history of the Arizaro Basin and surrounding arc suggest dynamic processes associated with lithospheric removal. Although analogue and numerical models support this hypothesis, the history of crustal thickness in response to lithospheric removal remains unconstrained. Here, we used a novel approach exploiting the geochemistry of detrital zircons from volcanic ashes intercalated within the Arizaro Basin stratigraphy to reconstruct the paleocrustal thickness of the neighboring magmatic sources throughout the Cenozoic. Our data indicate that the sources of volcanism for the Arizaro Basin were characterized by relatively thick crust (∼53 km) since ca. 36 Ma. Thickening between ca. 20 and 13 Ma and thinning after ca. 13 Ma are consistent with formation and subsequent removal of a crustal root under the nearby arc and Aguas Calientes caldera.

Ontogeny and associated changes of the extinct sloth Simomylodon uccasamamensis (Xenarthra, Mylodontidae) from the Pliocene of the eastern Puna, Argentina.

Within Xenarthra (Eocene-Recent), Folivora developed (late Eocene-Recent) a remarkable diversity with respect to ecology and taxonomy over its evolutionary history. Knowledge of the diversity achieved by members of this clade in high-altitude areas of South America (i.e., Altiplano and Puna regions of Peru, Bolivia, and northwestern Argentina) has been improved in recent decades. A particular example involves the late Neogene Mylodontidae Simomylodon uccasamamensis, known mostly from multiple specimens recovered from the Bolivian Altiplano. Although several anatomical descriptions of this ground sloth have been published, almost nothing is known about its ontogenetic development and the associated morphological changes. Here we describe and compare new specimens of S. uccasamamensis from the upper level of the Tafna Formation (Pliocene) in the eastern Puna (ca. 3800 masl), Argentina, representing the southernmost record of this species. The new material is represented by specimens showing different ontogenetic stages, from infant to adult. One subadult specimen reached an estimated body mass of ca. 232 kg. The comparative study of external and internal morphology (the latter obtained from CT scans and radiography) shows remarkable changes in the mandible and molariforms associated with ontogeny; in addition, evidence suggests that the mfs2-3 are the first functional teeth, followed by mf1 and cf1. Based on our body mass estimates (ca. 232 kg.), we inferred an average lifespan of 14 years, 9-month gestation time, and sexual maturation at 4.1 years, quite similar to the values we obtained based on estimated body masses of adult specimens from Bolivia published by previous authors. Along its latitudinal distribution (ca. 14° S-21° S) S. uccasamamensis co-occurred with other ground sloths (e.g., Megatheriinae, Thalassocninae, and Scelidotheriinae), suggesting niche partitioning. The presence of this medium-sized ground sloth is consistent with the similarity between the faunas of eastern Puna and the Bolivian Altiplano during the Pliocene, which is also concordant with what was observed in other clades, such as Rodentia and Notoungulata.

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.

Phylogenomics of Puya (Bromeliaceae): Evolution in the Andean slopes and sky island ecosystems

AbstractPhylogenomics enhances our understanding of plant radiations in the biodiverse Andes. Our study focuses on Puya, primarily Andean and a part of the Bromeliaceae family. Using a phylogenomic framework based on the Angiosperms353 probe set for 80 species, we explored Puya′s phenotypic evolution and biogeography. Divergence time analyses and ancestral area estimations suggested that Puya originated in Central Coastal Chile around 9 million years ago (Ma). Subsequently, it dispersed to the dry valleys of the Central Andes and Puna regions between 5–8 Ma, leading to the emergence of major lineages. Key events in the last 2–4 million years include the recolonization of Chilean lowlands and dispersal to the northern Andes via Peru's Jalcas, facilitating passage through the Huancabamba depression. This event gave rise to the high‐elevation Northern Andes clade. Using phylogenetic comparative methods, we tested the hypothesis that adaptation to the Andes' island‐like high‐elevation ecosystems was facilitated by unique leaf and floral traits, life history, and inflorescence morphology. Our findings suggest correlations between inflorescence axis compression, protective bract overlap, and high‐elevation living, potentially preventing reproductive structure freezing. Semelparity evolved exclusively at high elevations, although its precise adaptive value remains uncertain. Our framework offers insights into Andean evolution, highlighting that lineages adapted to life in dry ecosystems can easily transition to high‐elevation biomes. It also underscores how the island‐like nature of high‐elevation ecosystems influences phenotypic evolution rates. Moreover, it opens avenues to explore genetic mechanisms underlying adaptation to extreme mountain conditions.

Eutrombicula cochinocaensis infestation in llamas (Lama glama) in the Puna region of Argentina.

This paper aims to describe a case of trombiculosis in llamas from the Puna region of Argentina caused by Eutrombicula cochinocaensis. Trombiculosis is a parasitic infestation caused by the larval form of trombiculid mites, commonly known as chigger mites. Six adult llamas out of eighteen (33%) were infested and showed dermatitis, hyperemia, and crusts together with an orange-dotted pattern. The chigger mites were found mainly in the hind limbs and the abdomen. Microscopic identification of E. cochinocaensis was made by phase-contrast microscopy. Then, a histopathological study of the affected animals' skin was performed. Histological findings included dermatitis withmainly lymphocytic infiltrate, pustules, crusts, hyperkeratosis, and the mites' stylostomes in the dermis and epidermis. This is the first report of trombiculosis caused by E. cochinocaensis in llamas from Argentina. Mites of the family Trombiculidae are vectors of certain diseases to humans and animals and are therefore of sanitary and productive importance.

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

Deriving targeted intervention packages of nature-based solutions for climate change adaptation and disaster risk reduction: A geospatial multi-criteria approach for building resilience in the Puna region, Peru

Emergent complex climate risks challenge conventional approaches for climate adaptation (CCA) and disaster risk reduction (DRR). This situation demands new ways of addressing climate risks with integrated solutions. Nature-based Solutions (NbS) are promising CCA and DRR given their cost-effectiveness, multifunctionality and low-regret condition in addressing a wide range of risks exacerbated by climate change. However, little attention has been paid to exploring methodological approaches for combining NbS to reduce climate risks. Still, selecting the appropriate and effective combination of NbS is a challenging task. This research applies a geospatial multi-criteria approach for developing intervention packages of NbS for CCA and DRR and applies this innovative methodology to a case study area in the Puna region in Peru. The study started with an in-depth literature analysis coupled with a participatory process with local experts to identify and select locally valid NbS for CCA and DRR. Building upon that, the overall multi-criteria approach was developed, which consists of a matrix-based procedure to evaluate the applicability of relevant measures and their feasibility of being combined in intervention packages. Then, the multi-criteria analysis was integrated into a Geographic Information System using a spatial analysis model to map suitable intervention areas. Next to the methodological innovation, the multi-criteria approach was applied to a case study area to generate a place-based intervention package for addressing the risk of reduced water provision considering climate change conditions, with its respective potential intervention sites differentiated by the appropriate measures. This methodological approach is a novel and pragmatic support tool that helps practitioners design more robust and effective interventions for building resilience to climate change. Furthermore, this methodological approach involves shifting the perspective from activities focused on “one-size-fits-all-solution” to "multi-solution" strategic interventions that address climate risks more comprehensively, recognizing the dynamics and complexities of the social-ecological systems. The authors encourage researchers and practitioners to transfer the methodological approach to other contexts and, with that, accelerate the efficient and targeted implementation of NbS for building resilience to climate change.

Ordovician chitinozoans and review on basin stratigraphy, biostratigraphy and paleobiogeography of northern Argentina along the Proto-Andean margin

Ordovician strata exposed across the Cordillera Oriental and the Sierras Subandinas in northwestern Argentina were part of a large retroarc foreland basin developed along the Proto-Andean margin within the Central Andes in South America. A revised chitinozoan biostratigraphy along and across-strike for the Tremadocian, Floian, Dapingian, Katian and Hirnantian stages, calibrated with other fossil groups in the basin, allow pinpointing the most characteristic events that affected the basin fill testing global versus local controls in accommodation, and suggesting comparisons with other peri-Gondwanan records. According to the chitinozoan data, the glacially-related Ordovician deposits in northwestern Argentina are restricted to the Hirnantian, and unconformably overlie late Katian deposits. In the Caspalá area (Cordillera Oriental), an interval with synsedimentary deformation and reworked chitinozoans correlate with glacially-related deposits in other sites of the eastern part of the basin (Río Capillas and Mecoyita areas). A glacial waning stage is determined by a thin interval of organic‐rich black shales with sparse dropstones at the top of the Zapla Formation, containing Spinachitina oulebsiri associated with Desmochitina gr. minor, which together are typical latest Hirnantian components in other regions of Gondwana. Our study strengthens the foreland systems tract for the Ordovician Central Andean Basin with a volcanically fed interarc and foredeep depozone to the west (Puna region); a lower-accommodation forebulge depozone in the central area (mostly the Cordillera Oriental region); and a backbulge depozone (Sierras Subandinas and Sierras de Santa Bárbara) extending as far as the eastern Paraná Basin (reaching Paraguay and Brazil). Contemporaneous unconformities driven by global sea-level fluctuations were amplified or reduced due to deepening-narrowing or widening-shallowing, allowing contrasted accommodation, respectively associated to loading and relaxation. Ordovician chitinozoans from the Central Andean Basin indicate Northern, Western and peri-Gondwanan affinities, although locally some more cosmopolitan species described in Baltica, Avalonia and South China, are also recorded.

In situ growth of modern oncoids from Salado river, Salar de la Laguna Verde Complex, Argentina

This study explores a modern oncoids deposit in the Salado river, a high-altitude brackish river in the Puna region of Catamarca province, Argentina. This contribution focuses on oncoids features at macro-, meso-, and microscale as tools to provide insights into mechanisms of development and environmental information. Based on a detailed sedimentological, petrographic, and biodiversity analyses, it is suggested a primarily in situ growth of the oncoids, without being regularly overturned. Four key features are considered supporting this interpretation: (1) oncoids are placed in a stable position being partially buried in the substrate; (2) the existence of an attached thin biofilm outlining the contact of oncoids with the substrate which indicate their stable position during growth, at least for a certain period; (3) the carbonate cortexes display an uneven thickness being the uppers up to 1–2 times thicker than the lowers, suggesting asymmetrical growth during oncoids development; (4) well-preserved surface ornamentation (e.g., pustules) on the upper side in contrast with smooth bottom cortexes in contact with the substrate. Additionally, an integral analysis of the geochemistry of the river water and stables isotopes values from carbonate oncoids, suggest that water mixing (e.g., thermal and fresh-water inputs), high evaporation rates, and CO2 degassing are the main processes that promote calcite precipitation and therefore oncoids growth. Also, the role of bacteria and diatoms on the microstructure development as well as their possible implications on carbonate precipitation is discussed.

A snapshot of mid Eocene landscapes in the southern Central Andes: Spore-pollen records from the Casa Grande Formation (Jujuy, Argentina).

The southern Central Andes-or Puna-now contains specialized plant communities adapted to life in extreme environments. During the middle Eocene (~40 Ma), the Cordillera at these latitudes was barely uplifted and global climates were much warmer than today. No fossil plant remains have been discovered so far from this age in the Puna region to attest to past scenarios. Yet, we assume that the vegetation cover must have been very different from what it looks today. To test this hypothesis, we study a spore-pollen record from the mid Eocene Casa Grande Formation (Jujuy, northwestern Argentina). Although sampling is preliminary, we found ~70 morphotypes of spores, pollen grains and other palynomorphs, many of which were produced by taxa with tropical or subtropical modern distributions (e.g., Arecaceae, Ulmaceae Phyllostylon, Malvaceae Bombacoideae). Our reconstructed scenario implies the existence of a vegetated pond surrounded by trees, vines, and palms. We also report the northernmost records of a few unequivocal Gondwanan taxa (e.g., Nothofagus, Microcachrys), about 5,000 km north from their Patagonian-Antarctic hotspot. With few exceptions, the discovered taxa-both Neotropical and Gondwanan-became extinct from the region following the severe effects of the Andean uplift and the climate deterioration during the Neogene. We found no evidence for enhanced aridity nor cool conditions in the southern Central Andes at mid Eocene times. Instead, the overall assemblage represents a frost-free and humid to seasonally-dry ecosystem that prevailed near a lacustrine environment, in agreement with previous paleoenvironmental studies. Our reconstruction adds a further biotic component to the previously reported record of mammals.

Lithium mining, water resources, and socio-economic issues in northern Argentina: We are not all in the same boat

Lithium mining in Argentina is often associated to social injustices, unequal access to information, and conflicts around issues such as water consumption. Different stakeholders hold different perceptions around the pros and cons of lithium mining. We identify here concerns regarding water resources, technical aspects of lithium mining, and social and economic aspects in four different sources of information: (1) Scientific articles; (2) Government reports; (3) Corporate reports; and (4) Newspaper articles. We found differences between the groups of documents analyzed. Scientific and newspaper articles share a wide spectrum of issues. Corporate and government reports are more focused and relate more heavily to social and economic aspects. Socio-technical issues, frequent in government reports and the media, do not seem relevant in corporate reports. Concerns about water resources and lithium mining are most prominent in scientific and newspaper articles. Government reports were the least concerned about water and the socio-environmental impacts of lithium mining, but focused on global markets, employment and technical development. Analyzing stakeholders’ concerns in the Argentine Puna region can help reveal power structures, connections, and discourses across different sectors and scales.

A rural education experience in the Puna region of Argentina

El propósito de este artículo es examinar los retos que enfrenta la escuela secundaria, ligada desde su origen a mandatos y formatos modernos, para su expansión hacia contextos rurales, en el marco de una creciente fragmentación del sistema educativo. El análisis propuesto se realiza a partir de la experiencia de escolarización de una joven de la región puneña argentina. El enfoque de investigación adoptado es el cualitativo la perspectiva la etnografía. Los resultados evidencian que,en el caso en estudio, la escolarización enfrenta retos y alberga posibilidades vinculadas a brindar conocimientos útiles para las comunidades rurales en la región, distanciándose de los propósitos de la escuela secundaria común, pero a la vez el acceso a la educación y los bienes que aporta la escuela representan la puerta de acceso a otros derechos, no solo para la estudiante sino también para su familia.

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.

Proteomic Signatures of Microbial Adaptation to the Highest Ultraviolet-Irradiation on Earth: Lessons From a Soil Actinobacterium.

In the Central Andean region in South America, high-altitude ecosystems (3500–6000 masl) are distributed across Argentina, Chile, Bolivia, and Peru, in which poly-extremophilic microbes thrive under extreme environmental conditions. In particular, in the Puna region, total solar irradiation and UV incidence are the highest on Earth, thus, restraining the physiology of individual microorganisms and the composition of microbial communities. UV-resistance of microbial strains thriving in High-Altitude Andean Lakes was demonstrated and their mechanisms were partially characterized by genomic analysis, biochemical and physiological assays. Then, the existence of a network of physiological and molecular mechanisms triggered by ultraviolet light exposure was hypothesized and called “UV-resistome”. It includes some or all of the following subsystems: (i) UV sensing and effective response regulators, (ii) UV-avoidance and shielding strategies, (iii) damage tolerance and oxidative stress response, (iv) energy management and metabolic resetting, and (v) DNA damage repair. Genes involved in the described UV-resistome were recently described in the genome of Nesterenkonia sp. Act20, an actinobacterium which showed survival to high UV-B doses as well as efficient photorepairing capability. The aim of this work was to use a proteomic approach together with photoproduct measurements to help dissecting the molecular events involved in the adaptive response of a model High-Altitude Andean Lakes (HAAL) extremophilic actinobacterium, Nesterenkonia sp. Act20, under artificial UV-B radiation. Our results demonstrate that UV-B exposure induced over-abundance of a well-defined set of proteins while recovery treatments restored the proteomic profiles present before the UV-challenge. The proteins involved in this complex molecular network were categorized within the UV-resistome subsystems: damage tolerance and oxidative stress response, energy management and metabolic resetting, and DNA damage repair.

Season-sex interaction induces changes in the ecophysiological traits of a lizard in a high altitude cold desert, Puna region.

Functional traits are those characteristics of organisms that influence the ability of a species to develop in a habitat and persist in the face of environmental changes. The traits are often affected by a multiplicity of species-dependent and external factors. Our objective was to investigate thermal biology of Liolaemus ruibali in a high altitude cold desert at the arid Puna region, Argentina. We address the following question: do sex and seasonal variations in environmental temperature induce changes in the ecophysiological traits? We measured and compared the operative temperatures between fall and spring; and between sexes and seasons, we compared the ecophysiological traits of lizards, microenvironmental temperatures and thermoregulatory behavior. Air and operative temperatures were different between seasons. We found an effect of season-sex interaction on field body temperatures, preferred temperatures, panting threshold and thermal quality. The voluntary and critical temperatures presented seasonal variation in relation to changes in environmental temperatures, suggesting thermal acclimatization. We note behavioral changes between seasons, with the substrate being the main resource for gaining heat in spring. We conclude that Liolaemus ruibali is an efficient thermoregulator; it is a eurythermic lizard and presents phenotypic plasticity in different ecophysiological and behavioral traits induced by sex and seasonality. In addition, we predict that this population could buffer the effects of projected global warming scenarios.

Composite microbialites: Thrombolite, dendrolite, and stromatolite associations in a modern environment, Pozo Bravo lake, Salar de Antofalla, Catamarca Puna, Argentina

ABSTRACT Pozo Bravo is a high-altitude Andean lake that harbors modern microbialites thriving in hypersaline conditions in the Salar de Antofalla, one of the driest sites on Earth and located in the Puna region of Catamarca, northwest Argentine. Due to the lake physiography, microbialites are restricted to a narrow belt following Pozo Bravo lake variations. Microbialites exhibit a wide range of external morphologies including domal, discoidal, tabular, and horseshoe-like bioherms which vary considerably in size, as well as large biostromal terraces. As documented by other studies on modern microbialites, external morphology appears to be mainly the product of the environmental setting. In Pozo Bravo lake, high evaporation rates and hypersalinity (driven by high temperature and strong winds), water-level fluctuations, and lake-bottom topography are major controlling factors. The distinctive feature of Pozo Bravo microbialites is their internal structure, showing a gradual transition from a thrombolitic core to dendrolitic structures and to a sharply overlying stromatolitic layer within a single microbialite. We suggest that these various microbialite textures represent a gradual change within an environmental gradient based on lake-level variations, and the influence of these environmental factors on biological activity, mainly by cyanobacteria and diatoms. The study of this site is particularly relevant given that it represents an active system where progressive changes in microbialite type (from thrombolites to dendrolites and stromatolites) are recorded, providing an excellent natural laboratory to study these textural changes from a mechanistic perspective, and it may provide insights for better understanding of the microbialite geological record. In addition, given that these systems are threatened by human activities (mining of lithium-rich brines), its study and preservation are necessary.

Widespread hydrothermal alteration overprinting epizonal Ordovician rocks in the Puna region of Argentina (Salta and Jujuy provinces)

X-ray-diffraction and textural studies under scanning electron microscopy (SEM) using backscattered electron images were employed to outline the thermal post-depositional evolution of Ordovician slates and metavolcanic rocks from four representative localities in southern Puna (the Sierra de Guayaos, the southern zone of the Sierra de Cobres, Cordón de Pozuelos, and Cordón del Gallego) and the Sierra de Cochinoca-Escaya in northern Puna of Argentina. In the case of a meta-andesite that in a previous study had displayed complex clay mineralogy, additional XRD analysis along with a detailed TEM study was performed.Clay mineralogy, Kübler index and chlorite geothermometry indicated that the rocks had undergone prograde metamorphic evolution attaining the epizone. Textural evidence proves that the metamorphic event was syntectonic with the folding that affected this succession, producing a conspicuous slate cleavage in sedimentary and volcanic rocks. Afterwards, the rocks were affected by hydrothermal alteration that produced retrograde changes in mineralogy at centimeter, micron and nanometer scales. The hydrothermal fluid partially dissolved the metamorphic minerals and enhanced the crystallization of clays, kaolinite being the most frequent clay in the altered rocks. Alunite-jarosite was identified in one slate and also evidences of metal transport, suggesting an acid hydrothermal fluid and temperatures between 100 and ~ 300 °C. These data confirm that the Ordovician successions of southern Puna were affected by widespread hydrothermal alteration, as the equivalent rocks in northern Puna. The hydrothermal event was probably associated with the intrusion of the Eastern Puna Magmatic Belt.In the meta-andesite outcropping in the Sierra de Cochinoca-Escaya, HRTEM images and compositional mapping reveal the steps in the paragenetic evolution of the hydrothermal event that produced the alteration of mafic phenocrysts and the formation of intergrowths between high-charge corrensite, trioctahedral vermiculite, and kaolinite.

Morphoanatomy, histochemistry, essential oil, and other secondary metabolites of Artemisia copa (Asteraceae)

ABSTRACT Artemisia copa var. copa, popularly known as “copa”, “copa-copa”, “coa”, “copal” or “tola”, is an aromatic shrub that inhabits the high Andean peaks and the Puna region of Chile, Bolivia, and Argentina. Its aerial parts are sold in the local markets as a sedative, for the treatment of digestive disorders, hypertension, fever, urinary, respiratory infections, and frictions to relieve rheumatism. The morpho-anatomy and the histochemistry of the aerial parts of a native population of A. copa (Catamarca province, Argentina) were described in order to determine diagnostic characters and to identify the site of synthesis and storage of essential oils and other secondary metabolites. A. copa can be differentiated from other Artemisia species by a set of morpho-anatomical features, such as the presence of entire to segmented leaves; ribbed young stems with circular to quadrangular shape; schizogenous secretory ducts distributed (1–2) near the xylem at the midvein of the leaf and the cortex of the stems; non-glandular two-armed “T” shaped trichomes with 2–4 short uniseriated basal cells and biseriate capitate glandular trichomes. Epidermal cells, glandular trichomes, and secretory ducts were associated with the synthesis and accumulation of essential oil, triterpenic and phenolic compounds. Triterpenes (lupeol, α- and β-amyrin); phytosterols βsitosterol, stigmasterol, campesterol, and 24-methyl cholesta-5, 22-dien-3β-ol); sesquiterpene lactones (leucodin and achillin) and flavones (chrysosplenetin and jaceidin,) were identified in the chloroform extract. The essential oil showed chrysanthenone (76.9%), as the main component, accompanied by minor amounts of other mono- and sesquiterpenoids.

Taton dune field: wind selection across the Southamerican arid diagonal, Puna Argentina

Fiambala is a tectonic valley emplaced in the southern Puna region, Catamarca Province, Argentina. At the Western side of the valley, “bajadas” and tuff deposits are interfingered. Westerly winds cause an eastward sand transport, either by saltation or deflation. Sand is therefore accumulated eastwards, attached to the Fiambala Range. This sand ramp located close to the Taton village was surveyed in terms of its morphology and sand composition. The central section of the valley is occupied by the Abaucan River, which runs across the dune field. Three oases developed at these aggradation plains: Palo Blanco, Medanitos and Fiambala. These localities however have been threatened by desertification processes in the last years. Three profiles were described along the aggradation plain of this valley. The transversal and longitudinal dunes of Taton are composed of fine sand with 12-28% of volcanic ash, deposited within the last 5500 years. Grain-size selection was caused by aeolian transport processes. Dune ramps developed in areas dominated by sand transport while loess-sized material is deflated outside the valley.

Assessing Dendrochronological Potential of Escallonia myrtilloides in the High Andes of Peru

There is a significant dendrochronological gap in the Puna of the central Andes of Peru, which motivates research on new species. In this study, we present the first tree-ring chronologies of Escallonia myrtilloides. We collected samples at San Pedro Saño and Sapallanga in Peru, analyzed the anatomical characteristics that delimit the annual growth rings, and developed two tree-ring chronologies through conventional dendrochronological techniques. The tree-ring chronologies cover the period 1940–2015 (76 years) for San Pedro Saño and 1960–2015 (56 years) for Sapallanga. The E. myrtilloides chronologies presented similar values of mean sensitivity, Rbar and EPS to those recorded for Polylepis tarapacana, Polylepis pepei, and Polylepis rugulosa in the Puna region. The analysis of the climate-growth relationships indicated positive correlations with precipitation and negative correlations with temperature in particular months of the current growing season (October–April). This precipitation/temperature-sensitive record highlights the high value of E. myrtilloides for future studies on the influence of climate on tree growth in the central Andes.