Atacama Desert Of Northern Chile Research Articles

Sensitivity of the Prime-Cam Instrument on the CCAT-Prime Telescope

CCAT-prime is a new 6 m crossed Dragone telescope designed to characterize the Cosmic Microwave Background (CMB) polarization and foregrounds, measure the Sunyaev-Zel'dovich effects of galaxy clusters, map the [CII] emission intensity from the Epoch of Reionization (EoR), and monitor accretion luminosity over multi-year timescales of hundreds of protostars in the Milky Way. CCAT-prime will make observations from a 5,600 m altitude site on Cerro Chajnantor in the Atacama Desert of northern Chile. The novel optical design of the telescope combined with high surface accuracy ($<$10 $\mu$m) mirrors and the exceptional atmospheric conditions of the site will enable sensitive broadband, polarimetric, and spectroscopic surveys at sub-mm to mm wavelengths. Prime-Cam, the first light instrument for CCAT-prime, consists of a 1.8 m diameter cryostat that can house seven individual instrument modules. Each instrument module, optimized for a specific science goal, will use state-of-the-art kinetic inductance detector (KID) arrays operated at $\sim$100 mK, and Fabry-Perot interferometers (FPI) for the EoR science. Prime-Cam will be commissioned with staged deployments to populate the seven instrument modules. The full instrument will consist of 60,000 polarimetric KIDs at a combination of 220/280/350/410 GHz, 31,000 KIDS at 250/360 GHz coupled with FPIs, and 21,000 polarimetric KIDs at 850 GHz. Prime-Cam is currently being built, and the CCAT-prime telescope is designed and under construction by Vertex Antennentechnik GmbH to achieve first light in 2021. CCAT-prime is also a potential telescope platform for the future CMB Stage-IV observations.

Primer registro de Helicoperva titicacae (Hardwick) (Lepidoptera: Noctuidae) en Chile

The species Helicoperva titicacae is reported for the first time in Chile outside it’s of natural distributional range in Peru. During 2011-2013 adults of this moth were collected in forests of tamarugo (Prosopis tamarugo F. Philippi), located in the Pampa del Tamarugal National Reserve, Tarapacá Region, Chile (20°24´S - 69°44’W). There is no evidence of when this species could have expanded his range of distribution from southeast Peru to the Atacama Desert in Northern Chile. Helicoperva is a particularly invasive pest and his presence in the country could represents a potentialthreat to several crops and native forests.

A forest-specialist carnivore in the middle of the desert?Comments on https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.5230.

We present comments on an article recently published in Ecology and Evolution (“High‐resolution melting of the cytochrome B gene in fecal DNA: A powerful approach for fox species identification of the Lycalopex genus in Chile”) by Anabalon et al. that reported the presence of Darwin's fox (Lycalopex fulvipes), a temperate forest specialist, in the hyperarid Atacama Desert of northern Chile. We argue that this putative record lacks ecological support in light of ongoing research on this endangered species, and contains numerous methodological flaws and omissions related to the molecular identification of the species. Based on these issues, we suggest the scientific community and conservation decision‐makers disregard the alleged presence of the Darwin's fox in the Atacama Desert.

Two-year Cosmology Large Angular Scale Surveyor (CLASS) Observations: A First Detection of Atmospheric Circular Polarization at Q band

Abstract The Earth’s magnetic field induces Zeeman splitting of the magnetic dipole transitions of molecular oxygen in the atmosphere, which produces polarized emission in the millimeter-wave regime. This polarized emission is primarily circularly polarized and manifests as a foreground with a dipole-shaped sky pattern for polarization-sensitive ground-based cosmic microwave background experiments, such as the Cosmology Large Angular Scale Surveyor (CLASS), which is capable of measuring large angular scale circular polarization. Using atmospheric emission theory and radiative transfer formalisms, we model the expected amplitude and spatial distribution of this signal and evaluate the model for the CLASS observing site in the Atacama Desert of northern Chile. Then, using two years of observations at 32.°3 to 43.7 GHz from the CLASS Q-band telescope, we present a detection of this signal and compare the observed signal to that predicted by the model. We recover an angle between magnetic north and true north of −5.°5 ± 0.°6, which is consistent with the expectation of −5.°9 for the CLASS observing site. When comparing dipole sky patterns fit to both simulated and data-derived sky maps, the dipole directions match to within a degree, and the measured amplitudes match to within ∼20%.

The origins and implications of paleochannels in hyperarid, tectonically active regions: The northern Atacama Desert, Chile

Preserved remnants of fluvial activity in deserts constitute evidence for changing boundary conditions. The Atacama Desert of northern Chile is the global end-member for aridity, so the history of relict stream networks in this region is a record of how landscapes develop under extreme conditions. On Pampa de Tana in northern Chile (19.4°S), a series of channel forms that are presently inactive but in the past flowed westward are incised into the surface of a fault bounded, topographically elevated portion of the El Diablo Formation, a regionally extensive, relict pediment. We measure cosmic-ray produced 10Be, 26Al and 21Ne in fluvial deposits to date the timing of abandonment of three channels and couple this with topographic profile information from a SPOT-6 derived, 2 m resolution digital elevation model. We find two of the channels were abandoned approximately >5.6 Myr and 2.0 Myr ago. One channel is still capable of flow and has ages suggesting it was fluvially active within the last few hundred thousand years. Using the paleochannel ages measured here and published ages for the end of aggradation of the El Diablo Formation we estimate the rates of fluvial channel incision before channel abandonment, and uplift rates on the faults after channel abandonment. Maximum uplift rates of ~12 m/Myr over the last 2 Myr are found. In general, while rates of uplift are relatively low they are several-fold more rapid than the rates of fluvial incision prior to channel abandonment. This implies that westward channel flow was interrupted by uplift of topography above a blind NW-SE striking reverse fault that affects the Central Depression, an alluvial forearc basin. We consider also that shrinkage of the upstream catchment area by stream capture, promoted via headward erosion and lateral expansion of adjacent canyons (quebradas) could be a factor in the abandonment of the channels on Pampa de Tana. Our results highlight the polygenetic nature of this landscape and show that relatively minor amounts of fault displacement in hyperarid regions can have implications for stream network evolution. Even subtle topographic uplift upstream should be taken into account when fluvial deposits are used as proxies for long-term environmental conditions.

Population genomics of Tillandsia landbeckii reveals unbalanced genetic diversity and founder effects in the Atacama Desert

Abstract In hyper-arid habitats vegetation tends to be highly patchy with individual plant populations set widely apart from each other. In the Atacama Desert of northern Chile, rainfall is essentially absent, but fog occurring both at the coast and sometimes reaching inland areas supports patches of vegetation in an otherwise barren environment. Tillandsia landbeckii (Bromeliaceae), a epiarenic plant without functional roots, completely depends on fog as source for water, therefore it is found only in fog corridors. Here, we investigate the genetic connectivity within and between populations of T. landbeckii, using genome-wide single-nucleotide-polymorphisms (SNP) obtained through genotyping-by-sequencing (GBS). The 21 sampled populations from the Chilean Atacama Desert are distributed in three geographically ordered south to north clusters, with the southern cluster containing only one population that is genetically very distant from the others. From our study we obtained three genetic groups that corresponded to these three geographical clusters, with the exception of the two populations 16 and 18, where genetic affiliation lies at least in part with the central cluster. Further, our results show uneven distribution of genetic diversity among the populations with highest diversity in the central cluster. We found large amounts of shared heterozygous SNPs as well as negative values for the inbreeding coefficient FIS in the populations of the north and south. They indicate that these populations are strongly affected by clonal reproduction, while the populations in the center are mostly reproducing sexually. We interpret these data as the result of genetic bottlenecks due to founder events involving few dispersing genotypes combined with strong geographical isolation for the northern and southern populations, following stepping stone dispersal of Tillandsia during more climatically favorable episodes.

Ancient parasite DNA from late Quaternary Atacama Desert rodent middens

Paleoparasitology offers a window into prehistoric parasite faunas, and through studying time-series of parasite assemblages it may be possible to observe how parasites responded to past environmental or climate change, or habitat loss (host decline). Here, we use DNA metabarcoding to reconstruct parasite assemblages in twenty-eight ancient rodent middens (or paleomiddens) from the central Atacama Desert in northern Chile. The paleomiddens span the last 50,000 years, and include middens deposited before, during and after the Central Andean Pluvial Event (CAPE; 17.5–8.5 ka BP). The CAPE was a period of increased precipitation and vegetation change, which we also demonstrate was associated with changes in local rodent taxa. Thirteen parasite taxa (including lice, mites, ticks, nematodes and coccidians) were identified from the middens, nine of which were likely derived from rodent hosts and four from alternative (insect or avian) hosts. The former are consistent with parasites known to infect South American rodent hosts. At our conservative level of high taxonomic rank assignment, the parasites appear to have been resilient to the major perturbations in climate and host taxa associated with the CAPE, and finer taxonomic resolution would be required to detect whether any species turnover occurred within the identified parasite groups. Rodent paleomiddens are fast becoming an unrivaled source of genomic data that can be used to reconstruct past ecosystem change on multiple taxonomic, temporal and spatial scales providing new insights into ecological responses to global change.

Draft Genome Sequence of Bacillus safensis RP10, Isolated from Soil in the Atacama Desert, Chile

Genome analysis of Bacillus safensis RP10, a strain from the soil of Atacama Desert in northern Chile, reflects a bacterium adapted to live in soil containing high levels of heavy metals, high salt conditions, and low carbon and energy sources.

A 68 ka precipitation record from the hyperarid core of the Atacama Desert in northern Chile

Abstract The Atacama Desert in northern Chile is one of the driest deserts on Earth. Hyperaridity persists at least since the Miocene and was punctuated by pluvial phases. However, very little is known about the timing, regional spread and intensities of precipitation changes. Here, we present a new precipitation record from a sedimentary sequence recovered in a tectonically blocked endorheic basin that is located in the hyperarid core of the Atacama Desert. The chronostratigraphic framework of the record is given by a multi-disciplinary dating approach, suggesting an age of ca. 68 ka BP for the core base. The sequence consists of three sediment types, whose sedimentological and geochemical characteristics suggest different depositional processes that reflect different degrees in humidity. First, particularly fine-grained sediments with high clastic but low calcium sulfate and carbonate contents reflect a particularly dry climate with only sporadic precipitation events and fluvial supply via channel systems. Second, more coarse-grained sediments with lower clastic and higher calcium sulfate and carbonate contents reflect more moist conditions with stronger precipitation events that lead to fluvial activity not restricted to the channels but involving the slopes and plains in the catchment. Third, normally graded layers with an equally high proportion of calcium sulfate and carbonate reflect occasional high-precipitation events that caused sediment supply also from most distant parts of the catchment via severe flash floods. The sedimentary succession suggests that precipitation changes took place on orbital but also on millennial time scales. Rather moist periods occurred during most of MIS 2, several shorter periods within MIS 3 and parts of MIS 4. Comparison of the findings from the Huara record with selected climate records from continental and marine sites in South America suggests a strong precipitation heterogeneity across the Atacama. This heterogeneity is caused by pronounced differences in the dominating climate patterns and a shift from predominant summer rain in the north to winter rain in the south. Precipitation supply to the Huara clay plan is controlled by the atmospheric circulation rather than the surface temperature of the adjacent ocean.

Filling the observational gap in the Atacama Desert with a new network of climate stations

Abstract The Atacama Desert in northern Chile is the driest place on Earth. In this region, climate models are subject to large biases, especially precipitation is significantly overestimated. Meteorological observations in the region are sparse and limited to inhabited places at the coast or the foothills of the Andes. To fill this gap, a new network of 15 automatic weather stations has been established beginning April 2017. These stations do not only record standard meteorological parameters such as temperature, humidity and wind, but also soil temperatures and humidity, additionally a wetness sensor gives information about the occurrence of fog. Data from the first year(s) of this network show a very regular wind pattern with easterly winds during night and morning and westerly winds from noon to evening. This wind transports moisture from the Pacific Ocean into the desert which forms fog during the night which may account for a moisture supply on the order of the rare precipitation events in the region. A few precipitation events have been observed during the first years. The recorded data allows to distinguish between different sources: convective precipitation above the Altiplano, which in some cases extended to the western slope of the Andes, and troughs extending from mid latitudes to the region, directing moist air from the pacific into the region. Both of these mechanisms brought only some tenths of mm precipitation. In one case the accidental combination of flow over the Andes and a weak cut-off low above the Pacific led to moisture convergence off the coast of northern Chile and initiated a convective system moving south-east ward which brought for the region extreme precipitation of 3-10 mm.

A new species of Scrobipalpula Povolný (Lepidoptera: Gelechiidae) associated with Baccharis salicifolia (Asteraceae) in the Atacama Desert of northern Chile

ABSTRACTMale and female adults of Scrobipalpula wilsoni sp. nov. are described and illustrated from the coastal valleys of the Atacama Desert of northern Chile, based on specimens reared from leaf tier larvae collected on the shrub Baccharis salicifolia (Ruiz & Pav.) Pers. (Asteraceae). The morphology of the male genitalia of S. wilsoni resembles that of S. transiens Povolný, 1987, endemic to central Chile; however, morphological details of the uncus, gnathos, valva, the paired process of the sacculus and the phallus enable separation of the two species. Pairwise distances of a DNA barcode sequence of S. wilsoni with congeneric species ranged from 7.4 to 9.2% (K2P).urn:lsid:zoobank.org:pub:28FFDB34-2BBF-4E99-B35A-8BD84DF33E96

Aeolian transport of viable microbial life across the Atacama Desert, Chile: Implications for Mars

Here we inspect whether microbial life may disperse using dust transported by wind in the Atacama Desert in northern Chile, a well-known Mars analog model. By setting a simple experiment across the hyperarid core of the Atacama we found that a number of viable bacteria and fungi are in fact able to traverse the driest and most UV irradiated desert on Earth unscathed using wind-transported dust, particularly in the later afternoon hours. This finding suggests that microbial life on Mars, extant or past, may have similarly benefited from aeolian transport to move across the planet and find suitable habitats to thrive and evolve.

Adaptation to Extreme Environments in an Admixed Human Population from the Atacama Desert.

Inorganic arsenic (As) is a toxic xenobiotic and carcinogen associated with severe health conditions. The urban population from the Atacama Desert in northern Chile was exposed to extremely high As levels (up to 600 µg/l) in drinking water between 1958 and 1971, leading to increased incidence of urinary bladder cancer (BC), skin cancer, kidney cancer, and coronary thrombosis decades later. Besides, the Andean Native-American ancestors of the Atacama population were previously exposed for millennia to elevated As levels in water (∼120 µg/l) for at least 5,000 years, suggesting adaptation to this selective pressure. Here, we performed two genome-wide selection tests—PBSn1 and an ancestry-enrichment test—in an admixed population from Atacama, to identify adaptation signatures to As exposure acquired before and after admixture with Europeans, respectively. The top second variant selected by PBSn1 was associated with LCE4A-C1orf68, a gene that may be involved in the immune barrier of the epithelium during BC. We performed association tests between the top PBSn1 hits and BC occurrence in our population. The strongest association (P = 0.012) was achieved by the LCE4A-C1orf68 variant. The ancestry-enrichment test detected highly significant signals (P = 1.3 × 10−9) mapping MAK16, a gene with important roles in ribosome biogenesis during the G1 phase of the cell cycle. Our results contribute to a better understanding of the genetic factors involved in adaptation to the pathophysiological consequences of As exposure.

Chlorine isotope fractionation recorded in atacamite during supergene copper oxidation

In the Atacama Desert of northern Chile, large amounts of the copper hydroxy-chloride mineral atacamite (Cu2Cl(OH)3) are formed in the supergene oxidation zone of Cu deposits. Since atacamite requires saline water to form and is commonly preserved under hyperarid conditions, it has been proposed as a climate-sensitive mineral marker that can also provide relevant geochemical information regarding halogen (in particular chlorine) fluid sources during supergene Cu oxidation. However, chlorine stable isotope data for atacamite in Cu deposits are scarce and no experimental data for chlorine isotope fractionation between atacamite and water are currently available that could provide constraints on the possible mechanisms of fractionation. In this study we report δ37Cl values of atacamite along a thick (~100 m) and well-developed supergene enrichment profile at the Barreal Seco iron oxide-copper-gold (IOCG) deposit in the Atacama Desert. The δ37Cl values of atacamite along this profile range from +2.1‰ to −0.6‰ (mean = +0.4‰ ± 0.7‰; median = +0.3‰), and show a distinct trend with depth, characterized by higher δ37Cl values towards the top of the profile, with lower values at the bottom. In addition, the chlorine isotope compositions of experimentally synthetized atacamite crystals and coexisting CuCl2 solutions were determined at room temperature (23 °C). The per mil fractionation factor (Δ37Clatacamite-Cl) was determined at +0.75‰, showing that the heavy isotope (37Cl) is preferentially incorporated into atacamite. We used numerical models to test two possible scenarios that might explain the observed δ37Cl profile at Barreal Seco. A first scenario involves lowering of the water table with concomitant precipitation of atacamite, which removes Cl from solution following a Rayleigh fractionation process. This model qualitatively fits our observations but does not explain the full magnitude of the observed δ37Cl shift along the supergene profile. In contrast, a model that simulates Cl- diffusion following the upward injection of a deep brine that overlies fresh groundwater reproduces well the observed δ37Cl data, suggesting that seismic pumping of basinal brines, followed by Cl diffusion, is a feasible mechanism to explain the formation of atacamite at Barreal Seco. These data are a first step towards interpreting δ37Cl profiles of atacamite in Cu deposits in the Atacama Desert and exploring the potential use of stable chlorine isotopes to monitor Cu weathering and enrichment in supergene environments.

Revision of the genus Luispenaia Martínez (Coleoptera: Scarabaeidae: Melolonthinae: Tanyproctini), with description of three new species from the Atacama Desert, Chile.

The genus Luispenaia Martínez (Coleoptera: Scarabaeidae: Melolonthinae: Tanyproctini), is revised and four species are recognized: L. paradoxa Martínez, L. atacamensis new species, L. paposo new species, and L. paulseni new species. This genus is endemic to the Atacama Desert in northern Chile from the regions of Antofagasta to Coquimbo. Diagnostic characters, illustrations, a distribution map, and an identification key are provided for all species. Observations on the habitat, ecology, and distribution of species are given.

New microsatellites for the Atacama Desert endemic Balsamocarpon brevifolium (Fabaceae).

PremiseAlgarrobilla (Balsamocarpon brevifolium, Fabaceae) is an endemic xerophytic shrub restricted to the Atacama Desert in northern Chile. Extensive utilization of the region for coal production has endangered this species. Conservation efforts are underway, with genetic diversity analyses being key to the restoration of these populations.Methods and ResultsFifteen new microsatellite markers were developed for B. brevifolium and used to analyze three populations from the Atacama and Coquimbo regions in Chile. Microsatellites were highly polymorphic, with an average of 5.77 alleles per marker and an average level of expected heterozygosity of 0.72. These markers were evaluated and cross‐amplified on two related species (Senna cumingii and Caesalpinia angulata) with partial success.ConclusionsThe development of this set of markers permits an extensive study of B. brevifolium populations for conservation purposes.

Geomorphology of the coastal alluvial fan complex Guanillos, northern Chile

ABSTRACT The evolution of alluvial fans on the narrow coastal plain of the Atacama Desert in northern Chile is so far poorly investigated. Therefore, a detailed geomorphological map at a scale of 1:7500 of a coastal alluvial fan complex at Guanillos (21°58′S, 70°10.5′W) is provided as a first step to understand the fan’s morphogenesis. Geomorphological mapping was based on a digital elevation model with a resolution of 2 m generated from Pleiades-1 tri-stereo satellite imagery, derived terrain parameters, and on-site field mapping. The resultant map is used to characterize and categorize the overall morphology of the alluvial fan complex. In particular, linear features constructed by primary alluvial fan processes can be differentiated successfully from those developed by secondary processes. Furthermore, the advanced evolutionary state of the fan complex is revealed. We introduce a morphostratigraphic model comprising the fan’s prograde evolution, dissection, and successive abandonment of surface generations.

Dietary diversity in the Atacama desert during the Late intermediate period of northern Chile

The Pacific Ocean that flanks the hyperarid Atacama Desert of Northern Chile is one of the richest biomass producers around the world. Thus, it is considered a key factor for the subsistence of prehistoric societies (including mixed-economy groups), that inhabited its coastal ecosystems as well as the neighboring inland areas. This study assesses the Arica Culture groups' diet (Late Intermediate Period; 1000–1530 CE), through stable isotope (on bone-collagen; δ13C and δ15N) and dental pathology data. Seventy-seven (n = 77) individuals from two inland (LLU54 and AZ8) and one coastal (CAM8) archaeological sites were studied. Results show an important, but lower than predicted by earlier studies, contribution of marine resources in the diet of all three groups. Dental pathologies and stable isotopes indicate that these groups' diet varied in correlation with their distance to the Pacific Ocean as well as group and individual preferences. The results challenge the idea that Arica Culture groups depended heavily on marine resources for their subsistence. In contrast, this study shows both that the Arica Culture groups’ diet was diverse, and that the terrestrial resources consumed were mostly contributed by C3/CAM plants instead of maize.

The interior frontier: Exchange and interculturation in the Formative period (1000 B.C.-A.D. 400) of Quillagua, Antofagasta region, northern Chile

While the village of Quillagua, a riparian oasis in the hyperarid Atacama Desert of northern Chile, is of limited modern importance, there is strong evidence to support the contention that during different prehistoric periods the village was a frontier between the populations of the Pampa, the Pacific Coast, the Loa River, and the Salar of Atacama. Indeed, it can be argued that it served as a node for systems of inter-regional exchange. Archaeological evidence indicates that this frontier function may have its origins as early as the Formative Period (1000 B.C.-A.D. 400), a crucial era of regional cultural change. Scholarship from across the social sciences suggests that frontier/border spaces can be dynamic zones of cultural innovation and that prolonged inter-group contact at such spaces can change perception and behavior, notions that we test through isotopic analysis and multi-source mixture modeling of individuals from two distinct precincts of Formative Period Quillagua. Ultimately, based on our paleodietary reconstructions, we find that some individuals from Quillagua were not simply engaged in systems of inter-regional economic exchange, but that their involvement likely fomented the creation of novel cultural forms.

Ecological fidelity and spatiotemporal resolution of arthropod death assemblages from rodent middens in the central Atacama Desert (northern Chile)

Evaluating the magnitude and direction of biases affecting the ecological information captured by death assemblages is an important prerequisite for understanding past, present, and future community-environment relationships. Here, we establish the ecological fidelity and spatiotemporal resolution of an overlooked source of fossil remains: the soil arthropod assemblages found in rodent middens (that span from the present to >44,420 cal yr BP) collected in the central Atacama Desert of northern Chile. We evaluated the “live-dead agreement” across four sources of soil arthropod data; two contemporary surveys of live communities (i.e., live), and two sources of death assemblages (i.e., dead). Although live-dead agreements and diversity indices are highly variable among samples (live and dead assemblages), our results consistently demonstrate that an average fossil midden (i) better captures the structure and composition of living communities than species richness per se; (ii) offers a spatially-resolved picture of those communities at local scales; and (iii) is only weakly affected by time-averaging. The fine spatiotemporal resolution of fossil midden records in the Atacama, and most likely other areas of the world where rodent middens occur offers ecological information on the structure and composition of fossil arthropod assemblages potentially over many thousands of years. This information is reliable enough to establish historical baselines before past and ongoing anthropogenic impacts.