Andes Of Central Chile Research Articles

10Be chronology of the Last Glacial Maximum and Termination in the Andes of central Chile: The record of the Universidad Glacier (34° S)

Reconstructing mid-latitude glacier variations is a prerequisite for unveiling the interhemispheric climate linkages and atmospheric-ocean forcings that triggered those changes during the last glacial cycle. Nonetheless, the timing, magnitude, and structure of glacier fluctuations in the southern mid-latitudes remain incomplete. Here, we present a new 10Be chronology of the Universidad Glacier in the Andes of central Chile (34° S, 70° W; ∼2500 m a.s.l.) based on 21 cosmogenic-exposure ages of boulders on discrete moraine ridges defining former ice margins. Our findings include the mapping and dating of three moraines, UNI I, UNI II, and UNI III, located ∼20 km, 15 km, and 10 km down-valley from the present-day glacier front, respectively. The 10Be exposure ages of the UNI I moraine range from 135.9 ± 7.1 to 51.4 ± 2.7 ka (n = 3). The UNI II moraine gave a mean age of 18.0 ± 0.9 (n = 15) and the UNI III moraine yielded a mean age of 13.9 ± 0.8 ka (n = 3). The UNI I moraine implies the largest ice extent during a pre-Last Glacial Maximum (pre-LGM) period, including the penultimate glaciation. The UNI II is a moraine complex that represents cold and humid conditions in central Chile at the end of the LGM, which we attribute to the northward-shift of the Southern Westerly Winds (SWW). The UNI III moraine represents a return to glacial conditions interrupting the Termination, evidencing both a double-step deglacial trend observed through the southern middle and high latitudes at the end of the last ice age. The Andes at this subtropical latitude record a global signal of glacial and climate change.

A Late-Pleistocene confined volcanic debris avalanche promoted by hydrothermal alteration at the Tinguiririca volcano (Andes of Central Chile)

Distinguishing volcanic debris avalanche deposits from other epiclastic breccia could be complex. For more than 60 years, the Tinguiririca deposit (sourced from the homonymous volcano) in the Andes of Central Chile has been described by different authors as glacial moraines, a lahar, a volcanic debris avalanche, and even a debris flow deposit. To decipher its obscured origin and emplacement dynamics, we have carried out a detailed investigation of its distribution, contact relationships, sedimentology, and facies. Our findings unravel that the 57 km-long deposit is 5 to 300 m thick, totalling a reconstructed volume of 3.64 ± 0.05 km3. It is composed of unsorted heterometric breccias formed by clasts and blocks arranged in mixed and matrix facies characterised by distinctive lithological domains. In general, three clasts lithologies are dominant, consisting of black and grey andesites and hydrothermally altered clasts with jigsaw cracks and fractures. The deposit overlies terraced colluvium along the valleys and forms hummocks and ridges. Emplacement velocities estimates range from 39.6 m/s to 108.4 m/s. Therefore, the Tinguiririca deposit should represent a massive volcanic debris avalanche that formed after a lateral collapse that affected the ancient Tinguiririca Volcanic Complex, during the Late Pleistocene (between 45 ± 18 and c. 19.2 ± 1.2 ka). The abundance of hydrothermal minerals within the deposit's matrix and clasts (i.e., illite, phengite, epidote, tridymite, chlorite, hematite, jarosite, and alunite) all represent the volcano's hydrothermal system that likely favoured rock weakness and edifice collapse. Finally, the new interpretation is valuable for evaluating volcanic hazards and requires further mapping and research efforts.

PORPHYRY COPPER RECURRENCE IN THE ANDES OF CHILE AND ARGENTINA

Abstract Porphyry Cu deposits in the Chilean and Argentinian central Andes occur in a series of orogen-parallel magmatic arcs, which migrated episodically eastward since the Early Cretaceous. The three Cenozoic belts, corresponding to Paleocene-early Eocene, middle Eocene-early Oligocene, and Miocene-early Pliocene epochs, cut obliquely across a composite belt of subeconomic porphyry Cu mineralization formed at several times during the Late Carboniferous to Triassic interval. Based mainly on U-Pb zircon and Re-Os molybdenite ages, 10 Cenozoic porphyry Cu centers, including major deposits in all three of the Cenozoic belts, occupy the same sites as late Paleozoic-Triassic porphyry Cu mineralization where their respective magmatic arcs cross one another. The sites of recurrent porphyry Cu mineralization are believed to be underlain by long-lived dike conduits that were utilized at least twice—first in the late Paleozoic-Triassic and then again in the Cenozoic—to rapidly transmit hydrous magma from deep to shallow levels of the crust. Contenders for preferential dike localization include arc-oblique fault and subjacent ductile shear zones—transcrustal discontinuities—long hypothesized to be present in the region, particularly where they intersect magmatic arcs and associated porphyry Cu belts. Regardless of the controls on porphyry Cu recurrence, alteration zones hosted by late Paleozoic-Triassic volcanic and plutonic rocks in the central Andes of Chile and Argentina must be considered prime exploration targets for potentially large, high-grade Cenozoic porphyry Cu deposits.

Could invasive lagomorphs increase the predation risk for guanaco (Lama guanicoe) by puma (Puma concolor) in the Chilean Central Andes?

Could invasive lagomorphs increase the predation risk for guanaco (Lama guanicoe) by puma (Puma concolor) in the Chilean Central Andes?

Late Pleistocene to Holocene glacial, periglacial, and paraglacial geomorphology of the upper Río Limarí basin (30–31° S) in the Andes of central Chile

ABSTRACT We present a field-based reconstruction of the geomorphology in the Subtropical Andean mountains of the Limarí basin, semiarid central Chile (30–31° S). Fieldwork campaigns and remote-sensing analysis served for detailed geomorphological mapping at four formerly glaciated valleys in the heads of the Combarbalá and Río Hurtado sub-basins. We identify a mosaic of glacial, periglacial, and paraglacial landforms. Glacial landforms include a massive dead-ice moraine complex, with thermokarst and debris-filled fractures suggesting former ice-cored moraine degradation. This landform is superimposed by transversal and arcuate ridges suggesting active-ice processes. Periglacial landforms such as rock glaciers, gelifluction, and protalus lobes occur in cirques and U-shaped valleys, but also on moraine deposits. Paraglacial processes are indicated by talus accumulation in those formerly glaciated slopes. The geomorphological imprint is evidence for the interaction and succession between glacial, periglacial, and paraglacial dynamics from the Late Pleistocene to the present.

Glacial and volcanic landforms in the upper catchment of Claro River, Central Chile (35.5°S): A Late Quaternary geomorphological case study

AbstractThe upper catchment of the Claro river is located within the Transitional Southern Volcanic Zone in the Maule Region of Chile (35.5°S), at the foothills of Manantial Pelado volcano, a Pleistocene stratovolcano whose morphology suggests the occurrence of important glacial processes in the area. The observed glacial landforms can be sequenced and associated with episodes of volcanic activity. Different units of volcanic and glacial origin were identified based on field observations, detailed mapping, and digital elevation model and satellite image analysis. The contact relations between them made it possible to discern four events that can be linked to Marine Isotope Stages 8, 6, 4‐2, and to the Neoglacial. We propose seven stages in the geomorphological evolution from the late Pleistocene to the late Holocene, where there is coexistence between volcanic and glacial episodes, such as the emplacement of the Manantial Pelado volcano overlying the Abanico and Cola de Zorro formations; a subsequent debris avalanche; the enlargement of the Del Indio valley during the Penultimate Glaciation; the construction of Cerro Redondo (a minor eruptive center at the head of Del Indio valley); ongoing fluvial incision; and Neoglacial advances. The relative chronology proposed in this work contributes to clarifying the Pleistocene–Holocene geomorphological history in this catchment and to further understand the interplay between volcanic and glacial processes in the central Chilean Andes during the Quaternary.

Phylogeny of Berberidopsidales based on nuclear and chloroplast loci, with the description of a new species of Berberidopsis endemic to Central Chile

AbstractBerberidopsidales comprises two families: monotypic Aextoxicaceae (Aextoxicon punctatum in Chile and Argentina) and Berberidopsidaceae. The latter includes Australian monotypic Streptothamnus (S. moorei) and Berberidopsis (B. beckleri in Australia and B. corallina in Chile). A new Berberidopsis species from the Central Chilean Andes is here described. Phylogenetic analyses based on nuclear and chloroplast data clarified the relationships within Berberidopsidales. The new species, Berberidopsis granitica, is sister to the Chilean endemic B. corallina, and this clade is sister to the Australian B. beckleri. The dated molecular phylogeny places the split between the South American B. corallina and B. granitica into the late Miocene/early Pleistocene and the split between South American and Australian Berberidopsis to the late Miocene and Pliocene, suggesting transoceanic dispersal rather than vicariance. Climatic niche analyses show two distinct and non‐overlapping climatic niches for the Australian and southern South American species. Berberidopsis granitica and B. corallina also differ clearly in their habitat and morphology, in addition to their climatic niche. Berberidopsis granitica has a very restricted distribution area and grows in the Andes under montane climatic conditions, unique within Berberidopsidales.

Drivers of plant diversity, community composition, functional traits, and soil processes along an alpine gradient in the central Chilean Andes.

High alpine regions are threatened but understudied ecosystems that harbor diverse endemic species, making them an important biome for testing the role of environmental factors in driving functional trait-mediated community assembly processes. We tested the hypothesis that plant community assembly along a climatic and elevation gradient is influenced by shifts in habitat suitability, which drive plant functional, phylogenetic, and spectral diversity. In a high mountain system (2400-3500 m) Región Metropolitana in the central Chilean Andes (33°S, 70°W). We surveyed vegetation and spectroscopic reflectance (400-2400 nm) to quantify taxonomic, phylogenetic, functional, and spectral diversity at five sites from 2400 to 3500 m elevation. We characterized soil attributes and processes by measuring water content, carbon and nitrogen, and net nitrogen mineralization rates. At high elevation, colder temperatures reduced available soil nitrogen, while at warmer, lower elevations, soil moisture was lower. Metrics of taxonomic, functional, and spectral alpha diversity peaked at mid-elevations, while phylogenetic species richness was highest at low elevation. Leaf nitrogen increased with elevation at the community level and within individual species, consistent with global patterns of increasing leaf nitrogen with colder temperatures. The increase in leaf nitrogen, coupled with shifts in taxonomic and functional diversity associated with turnover in lineages, indicate that the ability to acquire and retain nitrogen in colder temperatures may be important in plant community assembly in this range. Such environmental filters have important implications for forecasting shifts in alpine plant communities under a warming climate.

Monitoring surface velocity changes of rock glaciers in the Chilean Andes using DINSAR technique with PAZ imagery

Vertical deformation associated with the displacement of rock glaciers in the upper Mapocho river basin, in the central Andes of Chile, was monitored using a series of PAZ radar satellite images and the DInSAR technique. Forty-one PAZ images of ascending and descending orbit were processed with the Small Baseline Subset (SBAS) technique. Regarding the obtained results, it was estimated that the vertical displacement velocity of rock glaciers between October 9, 2019 and April 22, 2021 reached up to -22 mm/year and the movement in the W-E direction ranged from -47 to 38 mm/year. This remote sensing technique is a useful tool to measure the surface displacement of rock glaciers, compared to conventional techniques such as GNSS point measurements, especially in the semi-arid Andes, which is one of the most important reservoirs of these geoforms worldwide.

Capitana mine, Tignamar district, a unique tin – bismuth concentration in the Chilean Central Andes, 250 km west of the Bolivian Tin Belt: Link to the Proterozoic-Paleozoic basement Belen inlier and the Arequipa-Antofalla terrane, a probable remnant of Laurentia

The Capitana mine, Tignamar District, is a unique Sn-Bi concentration in the highlands of Arica, in the Chilean Central Andes. Tin deposits associated with Triassic to Pliocene age igneous rocks are plentiful in the Tin Belt of Peru, Bolivia, and NW Argentina, but have not been reported in Chile, where contemporaneous rocks formed metallogenic belts rich in Fe, Cu, Mo, Ag and Au. We describe vein ore from Capitana mine, a small but exceptional Sn-bearing Pb-Bi-Ag-Cu-Sb-As epithermal deposit in the Tignamar (or Ticnamar) district in the high Andes of Arica, Chile, ca. 250 km west of the Bolivian Tin Belt. Fluid inclusions in vein quartz trapped a non-boiling, low salinity (<∼4 wt% NaCl equiv.), moderate T fluid (minimum T ∼ 220 °C) prior to metal precipitation. Flashing of this fluid, likely due to rapid changes in confining P, was synchronous with metal deposition; sulfosalt textures show evidence of syn-deformational growth. Although located within a district considered a porphyry copper system of Early Miocene age, it is likely that the Capitana deposit formed later, mainly as a result of regional hydrothermal activity related to compressive and transpressional tectonics as young as Pliocene. Common lead is 206Pb/204Pb 18.18; 207Pb/204Pb 15.61; and 208Pb/204Pb 38.53, significantly less radiogenic than that of Bolivian Sn deposits, and has a Paleozoic model lead age. These values point to affinities with a tectonically-emplaced inlier of crystalline basement of Proterozoic – Early Paleozoic age known as the Belen Metamorphic Complex, and with the Arequipa-Antofalla basement terrane, a probable remnant of Laurentia (North America), left behind during the dismemberment of the Rodinia Supercontinent. The complex mineralogy of Capitana vein, unlike other Chilean deposits, includes various sulphides and sulphosalts with Cu, Fe, Zn, Pb, Bi, Sn, Ag, As, Sb, Ga and In, and is exceptionally rich in U.

A multiproxy approach to reconstruct the Late Holocene environmental dynamics of the semiarid Andes of central Chile (29°S)

Mountain ecosystems located in the Andes cordillera of central Chile (29–35°S) have been strongly affected by the ongoing Mega Drought since 2010, impacting the snow cover, the surficial water resources (and thereby water storage), as well as the mountain biota and ecosystem services. Paleoenvironmental records in this part of the semiarid Andes are key to estimating the effects of past climate changes on local communities helping to forecast the ecological and biological responses under the aridification trend projected during the 21st century. Here we present a 2400-year multiproxy paleoenvironmental reconstruction based on pollen, diatoms, chironomids, sedimentological and geochemical data (XRF and ICP-MS data) of Laguna El Calvario (29°S; 3994 m a.s.l), a small and shallow Andean lake. Four main hydrological phases were established based on changes in the lithogenic and geochemical results associated with allochthonous runoff input and the subsequent response of the biological proxies. Between 2400 and 1400 cal yrs BP, wetter than present conditions occurred based on the intense weathering of the lake basin and the dominance of upper Andean vegetation. A decrease in moisture along with sub-centennial discrete wet pulses and lake-level changes occurred until ~800 cal yrs BP followed long-term stable climate conditions between 1850 and 1950 AD as suggested by a drop in vegetation productivity and low lake levels. From 1950 AD to the present, a decline in moisture with a severe trend to drier conditions occurring in the last decades occurred as reflected by an upward vegetation belt displacement around Laguna El Calvario along with a turnover of diatom assemblages and high productivity in the water column.

Atmospheric black carbon in a key location of the Chilean Central Andes: Identifying patterns, sources, and potential impacts

Black carbon (BC) has been identified as one of the primary contributors to climate change, primarily due to its exceptional capacity to absorb solar radiation. This leads to a reduction in the albedo of ice and snow surfaces, consequently accelerating their melting. In this work, measurements of atmospheric BC are presented, carried out from October 2016 to December 2019 in Portillo, Chilean Central Andes, in the NUNATAK-1 laboratory refuge (3000 m.a.s.l). This site is close to the Chile-Argentina border and is situated along a heavily trafficked road connecting the two countries. Owing to weather conditions, this route operates on a seasonal schedule, remaining open 24 h during warmer months, while in winter, traffic is restricted to the hours between 8 a.m. and 8 p.m. Access to vehicles is prohibited during periods of heavy snowfall. BC concentrations were continuously monitored by a Multi-Angle Absorption Photometer (MAAP). The variability and temporal cycles of BC levels were investigated in relation to local vehicular activity and meteorological parameters, through multiple linear regression analysis. Results show that vehicular traffic variations led to a systematic pattern in the atmospheric BC measured, with a preponderant role of meteorological factors. During the summer months, BC levels reached their peak (mean of 0.77 μg m−3), with maximum values recorded during the nighttime and early morning hours. In line with this finding, summer counted the highest number of vehicles circulating in the area. In contrast, the winter months exhibited lower average BC atmospheric concentrations compared to summer months (0.35 μg m−3), characterized by a distinct hourly profile. In a complementary way, forward trajectories using the HYSPLIT model were performed for various meteorological conditions. The findings indicated that emissions from the study area had the potential to extend to neighboring glaciers. This impact on the basins' hydrology, vital and fragile components of the Andean region, magnifies climate change effects in these cryospheric zones. Notably, the latest IPCC report highlights limited research on aerosol effects on mountain snow and glaciers. This study also presents the first estimates of high-altitude BC source assessments in Chile and South America. These insights could enhance global atmospheric models in mountainous regions, enhancing their accuracy and utility.

Friction and the Reconfiguration of Colbún's Waterscape: Manoeuvring Across Troubled Waters in the Chilean Central Andes

In the Maule basin, Chile, the domestication of the waters occurs below the line of a thousand meters of altitude, giving rise to the existence of a transition strip which the modernising processes and the elusive practices of mountain populations mutually infiltrate. The strip stands out as a site of confluence of the waters' diverse modes of being, below which stands a waterscape that recreates the environment to naturalise what, in another context, has been the object of dispossession. The Colbún dam and the Panimávida Resort &amp; Spa are iconic of this process in the Maule basin: while erasing all signs of dispossession, these interventions project the image of a narcissistic self-made civilisation. The study of the Colbún area in the Maule basin, central Chile, highlights the multiple historical ways of shaping waterscapes. Water goes through fluctuating conditions depending on how it becomes entangled with social processes. From indigenous daily practices to high-tech engineering, the article suggests the existence of a process of aestheticisation that encompasses the downward movement of the water from the glaciers in the high mountains towards the valleys. Likewise, different epistemologies seem to operate at both sides of the altitudinal divide. This article is both an account of the complex process of statecraft by means of infrastructure, and the overlapped and contested ways such a project imposes ways of framing the material world, more-than-human relationships, time, and urgencies.

Glacier slowdown and rapid ice loss in the Tinguiririca and Cachapoal Basin, Central Andes of Chile

The central region of Chile is home to nearly 10 million people, 60% of the country's population. This area's water supply is reliant on glacial meltwater from the Andes, especially during the dry summer months. However, the current ice volumes and rates of ice loss remain uncertain in many glacierized Andean basins. Our study investigated the dynamics of glaciers located in the high-altitude Tinguiririca and Cachapoal Basin over the period 2016–2022, by measuring their surface velocity and inverting for changes in ice thickness. We measured the glacier surface velocities using the Glacier Image Velocimetry toolbox on Sentinel 2 images, merging over 6000 individual velocity measurements into median annual velocity maps. We then used ice velocities as input for ice-thickness inversions to calculate ice-thickness maps and ice volumes using an ensemble of four different methods. We detect a decrease in surface velocity from 2016 to 2022 on the Universidad, Cortaderal, Norte Cipreses glaciers and southern part of the Palomo glacier, while the Cipreses glacier and the northern part of the Palomo glacier showed a decrease in velocity between 2016 and 2021 and then an acceleration in 2022. Ice thickness data shows an ice volume loss of between 0.34 ± 0.22 and 0.43 ± 0.18 km3/yr depending on the method used, equivalent to ∼25% of the total ice volume lost from 2016 to 2022. The current rates of ice volume loss are unsustainable beyond the next two decades, reducing or entirely removing the glacial contribution to streamflow and increasing pressure on local water resources.

Changes in Snow Surface Albedo and Radiative Forcing in the Chilean Central Andes Measured by In Situ and Remote Sensing Data

Snow-covered regions are the main source of reflection of incident shortwave radiation on the Earth’s surface. The deposition of light-absorbing particles on these regions increases the capacity of snow to absorb radiation and decreases surface snow albedo, which intensifies the radiative forcing, leading to accelerated snowmelt and modifications of the hydrologic cycle. In this work, the changes in surface snow albedo and radiative forcing were investigated, induced by light-absorbing particles in the Upper Aconcagua River Basin (Chilean Central Andes) using remote sensing satellite data (MODIS), in situ spectral snow albedo measurements, and the incident shortwave radiation during the austral winter months (May to August) for the 2004–2016 period. To estimate the changes in snow albedo and radiative forcing, two spectral ranges were defined: (i) an enclosed range between 841 and 876 nm, which isolates the effects of black carbon, an important light-absorbing particle derived from anthropogenic activities, and (ii) a broadband range between 300 and 2500 nm. The results indicate that percent variations in snow albedo in the enclosed range are higher than in the broadband range, regardless of the total amount of radiation received, which may be attributed to the presence of light-absorbing particles, as these particles have a greater impact on surface snow albedo at wavelengths in the enclosed band than in the broadband band.

Elevation provenance affects photosynthesis and its acclimation to temperature in the high-Andes alpine herb Phacelia secunda.

We analysed whether Phacelia secunda populations from different elevations exhibit intrinsic traits associated with diffusive and biochemical components of photosynthesis, and if they differ in acclimation of photosynthesis to warmer temperatures. We hypothesized that P. secunda will have similar photosynthetic performance regardless of altitudinal provenance and that plants from high elevations will have a lower photosynthetic acclimation capacity to higher temperature than plants from low elevations. Plants from 1600, 2800 and 3600 m a.s.l. in the central Chilean Andes were collected and grown under two temperature regimes (20/16 °C and 30/26 °C day/night). The following photosynthetic traits were measured in each plant for the two temperature regimes: AN , gs , gm , Jmax , Vcmax , Rubisco carboxylation kcat c . Under a common growth environment, plants from the highest elevation had slightly lower CO2 assimilation rates compared to lower elevation plants. While diffusive components of photosynthesis increased with elevation provenance, the biochemical component decreased, suggesting compensation that explains the similar rates of photosynthesis among elevation provenances. Plants from high elevations had lower photosynthetic acclimation to warmer temperatures compared to plants from lower elevations, and these responses were related to elevational changes in diffusional and biochemical components of photosynthesis. Plants of P. secunda from different elevations maintain photosynthetic traits when grown in a common environment, suggesting low plasticity to respond to future climate changes. The fact that high elevation plants had lower photosynthetic acclimation to warmer temperature suggests higher susceptibility to increases in temperature associated with global warming.

Fluid-Assisted Aggregation and Assembly of Magnetite Microparticles in the Giant El Laco Iron Oxide Deposit, Central Andes

The El Laco iron oxide mineral deposit in the Central Andes of Chile has attracted significant attention because of its uniquely preserved massive magnetite orebodies, which bear a remarkable similarity to volcanic products. To date, the outcropping highly vesicular and porous massive magnetite orebodies have received little attention from a microtextural point of view, limiting our understanding about the role of volcanogenic processes on iron mineralization. Here, we report the chemical composition of vesicular magnetite at El Laco using EPMA and LA-ICP-MS methods and provide detailed 2D and 3D imaging of the internal structure of these texturally complex magnetite ores by combining SEM observations, synchrotron radiation micro-X-ray fluorescence chemical mapping, and high-resolution X-ray computed microtomography. Our observations reveal the presence of abundant magnetite microspheres with diameters ranging from ∼100 to ∼900 μm, as well as dendritic microstructures forming interconnected networks up to a few millimeters in size. Two-dimensional microtextural and geochemical imaging of the microspheres show that these features are formed by multiple euhedral magnetite crystals growing in all directions and occur immersed within a porous matrix conformed by smaller-sized (∼2–20 μm) and irregularly shaped magnetite microparticles. These types of morphologies have been reported in hydrothermal vents associated with hydrovolcanic processes and commonly described in hydrothermal synthesis experiments of magnetite microspheres, suggesting precipitation from iron-rich fluids. A hydrothermal origin for the magnetite microparticles reported here is further supported by their geochemical signature, which shows a strong depletion in most minor and trace elements typical from magnetite precipitated from hydrothermal fluids in ore-forming environments. We propose that decompression, cooling, and boiling of fluids triggered massive iron supersaturation, resulting in the nucleation of magnetite microparticles or colloids, followed by self-assembly into larger and more complex microstructures. Our data from El Laco deposit agree with models invoking magmatic-hydrothermal fluids to explain the origin of the deposit and provide new insights on the potential role of iron colloids as agents of mineralization in volcanic systems.

When sunlight goes out, avoidance mechanisms are defective for protecting flowers from freezing damage

In high mountain species, flowers are considered the most frost-sensitive organs of plants. Such frost sensibility relates to the fact that most flowers do not tolerate ice formation in their tissues, suggesting that freezing avoidance mechanisms would be highly selected to protecting these vital organs from freezing damage. Despite this, the function and regulation of avoidance mechanisms in flowers have been poorly studied. This study assessed the importance of freezing avoidance mechanisms in alpine species from the central Chilean Andes. Reproductive shoots of 14 herbaceous species from the subalpine and low alpine belts in the central Chilean Andes were collected during peak flowering in the field and transported to the lab to study ice formation and propagation. The frequency and effectiveness of structural ice barriers (SIB) and the effect of inflorescence morphology on thermal decoupling were quantified by infrared thermography. SIBs were detected in 9 out of the 14 studied species but were effective only in three. Moreover, no thermal decoupling was detected in any studied species, independent of their inflorescence type. We conclude that SIBs and inflorescence morphology are insufficient to protect flowers from damage caused by night freezing events.

Geoheritage of Cajón del Maipo aspiring geopark: inventory, assessment, and opportunities for local development in the Andes of central Chile

Abstract Cajón del Maipo is a mountainous territory located in the Andes Cordillera of central Chile ( c. 5000 km 2 ), 48 km away from Santiago, and is a highly visited tourist destination. It reaches a maximum altitude of 6570 m, and its geology is controlled by the subduction regime between the Nazca and the South American plates. In its rocks, the Andean Tectonic Cycle is recorded, and its geodiversity includes active stratovolcanoes, thermal springs, tectonic structures, glacial and fluvial morphologies, landslides, marine fossils and abandoned mines. The area hosts an important and strained water system, with more than 800 glaciers that supply the city of Santiago with drinking water. This work shows the inventory of geoheritage of Cajon del Maipo, which includes 40 geosites. They were selected and assessed using a quantitative approach in the three main types of use (scientific, educational and touristic), and in their degradation risk. The results are displayed with an innovative synthetic map. Combining statistical quantitative and qualitative analysis, management priorities and opportunities for local development were identified. This inventory must be the framework for developing a geoconservation strategy, and the basis for the application of Cajon del Maipo as a UNESCO Global Geopark.

Meteorological export and deposition fluxes of black carbon on glaciers of the central Chilean Andes

Abstract. Air pollution in the central zone of Chile is not only a public health concern but also threatens water resources and climate, in connection with the transport and deposition of black carbon (BC) from urban centers onto the glaciers of the Andes. Chemistry-transport simulations reveal a seasonal dichotomy in the flux and latitudinal pattern of BC deposition on glaciers of the central Chilean Andes. The average deposition flux of BC on glaciers between 30 and 37∘ S is 4 times larger in winter, affecting mostly low-elevation glaciers, whereas the smaller summertime flux affects glaciers evenly, irrespective of their elevation. The contribution of emissions from the city of Santiago is dominant in summertime with more than 50 % along the Andes but minor in wintertime with less than 20 % even close to the capital city. Transport at larger scales and more local sources likely account for the remaining flux. The superimposition of synoptic-scale circulation and local mountain-valley circulation along the Andes drives the differences between summertime and wintertime deposition fluxes and generates a greater meteorological export potential during summer months. Future emissions and climate projections suggest that under the RCP8.5 scenario the gap between summertime and wintertime BC export and deposition flux could decrease, thereby pointing to summertime emission control gaining relevance. The chemistry-transport modeling approach for BC deposition on the Andes sheds light on the importance of the often disregarded summertime emissions on the radiative balance of its glaciers, particularly in the vicinity of Santiago.