Andean Mountain Groundwater, Drinking Water Sources, and Vulnerability: A Case Study in Central Chile

This chapter presents a study of the Diguillín basin in central Chile where geology is dominated by the Nevados del Chillan volcanic complex. The headwater of the basin has two watersheds: Renegado creek and Alto Diguillín. The hydrogeology was studied using field surveys, streamflow gauging, environmental tracers, and a hydrological model. Surface water balance does not fit for both watersheds because there is a deficit/excess of superficial runoff. Renegado soils are predominantly sands over a basement composed of fractured rock; infiltration of rain and snowmelt predominates over surface runoff, resulting in about 5 m3/s of depth groundwater that flows to the Diguillín River, discharging in a cluster of springs located 3 km downstream of the surface connection. Therefore, drinking water availability for the communities located at the Renegado watershed is limited to some springs that are located around the valley. There is a significant expansion of second home construction in the area of the Renegado watershed; because of its skiing and hot springs, it is a major tourism center. Due to the extensive use of septic tanks, located above the highly permeable soils that overlie the fractured rock aquifer, there is concern about how water quality may be affected

Burdigalian deposits of the Santa Cruz Formation in the Sierra Baguales, Austral (Magallanes) Basin: Age, depositional environment and vertebrate fossils

Indexación: Web of Science; Scielo.ABSTRACT. A succession of marine and continental strata on the southern flank of Cerro Cono in the Sierra Baguales, northeast of Torres del Paine, can be correlated with stratigraphic units exposed along the southern border of the Lago Argentino region in Santa Cruz Province, Argentina. These include the Estancia 25 de Mayo Formation and the basal part of the Santa Cruz Formation. The lithological correlation is also confirmed by detrital zircon ages (maximum age of 18.23±0.26 Ma) and a rich assemblage of terrestrial vertebrate fossils, biostratigraphically equivalent to a postColhuehuapian, pre-Santacrucian South American Land Mammal Age (SALMA) fauna, suggesting a range of 19 to 17.8 Ma. Similar ages have been obtained from the basal part of the Santa Cruz Formation at Estancia Quién Sabe in southwestern Argentina, supporting the assumption of a regional continuity between these deposits. A measured lithostratigraphic column is presented and the depositional environment is interpreted as a coastal plain with small, meandering rivers and ephemeral floodplain lakes. The sedimentation coincides with intensified uplift of the Patagonian Andes during the ‘Quechua Phase’ of Andean tectonism, which is reflected by a change in paleocurrent directions from northwest to east-northeast. Keywords: Burdigalian, Santa Cruz Formation, Santacrucian SALMA, ‘Notohippidian’ fauna, Meandering rivers.RESUMEN. Una sucesión de estratos marinos y continentales en el flanco meridional del cerro Cono, en la sierra Baguales, al noreste de Torres del Paine, se correlaciona con estratos al sur de la región de lago Argentino en la Provincia de Santa Cruz, República Argentina. Estas unidades incluyen la Formación Estancia 25 de Mayo y la parte basal de la Formación Santa Cruz. La correlación litológica es, además, confirmada por datación de circones detríticos (edad máxima de 18,23±0,26 Ma) y un variado ensamble de vertebrados fósiles terrestres de edad post-Colhuehuapense a pre-Santacrucense en la escala de Edades Mamífero Sudamericanas (EMAS), con un rango temporal de entre 19 a 17,8 Ma. Edades similares han sido reportadas para la parte basal de la Formación Santa Cruz, en estancia Quién Sabe, en el suroeste de Argentina, ratificando la continuidad regional entre estos depósitos. Se presenta una columna estratigráfica y se interpreta el ambiente de depositación como una llanura costera con pequeños ríos sinuosos y lagos efímeros. La edad de sedimentación coincide con el solevantamiento de los Andes Patagónicos durante la 'Fase Quechua', lo que se ve reflejado por un cambio en la dirección de las paleocorrientes desde el noroeste hacia el este-noreste.http://ref.scielo.org/csxwd

Caracterización de dos grupos de manantiales en el río Diguillín, Chile

La disponibilidad de agua en zonas de clima mediterráneo alcanza niveles críticos durante la temporada estival, que se caracteriza por escasez de precipitaciones y alta demanda de agua, por lo que el caudal base de los ríos es principalmente generado por deshielo o por la liberación de aguas subterránea. Este artículo presenta la caracterización de dos grupos de manantiales que producen el caudal base en la parte alta de río Diguillín, ubicado en la Cordillera Andina de la Región del Biobío, Chile (36.9° S). Un grupo está ubicado en la cabecera del río, en el Valle de Aguas Calientes, y el otro está ubicado en un sector denominado Agua Bonita. Se caracterizaron ambos grupos de manantiales, identificando los sistemas hidrogeológicos que drenan y el origen de la recarga de agua, considerando para ello información geológica y geomorfológica del lugar, así como las características químicas e isotópicas de muestras de aguas de ríos, manantiales y de precipitación. Los manantiales del Valle de Aguas Calientes aportan aproximadamente 2.5 m3/s desde un sistema acuífero ubicado al interior del Volcán Chillán; los manantiales de Agua Bonita aportan unos 4.5 m3/s desde un sistema de rocas fracturadas recargado por filtraciones de aguas lluvia en el valle del estero Renegado

Desarrollo educativo al servicio del desarrollo social

La publicación recoge las aportaciones y los trabajos realizados con motivo del "Proyecto de apoyo y fortalecimiento educacional en gestión directiva y competencias profesionales docentes", promovido por varias instituciones, coordinado por el Equipo de Desarrollo Organizacional (EDO) de la Universidad Autónoma de Barcelona; y subvencionado por la Agencia Española de Cooperación Internacional para el Desarrollo (AECID). La finalidad del proyecto, en el que se enmarcan las aportaciones de la publicación, es construir una red de cooperación y apoyo con y entre los centros educativos dependientes de la municipalidad de Coyhaique (Chile), para impulsar la mejora educativa y con ella el desarrollo social y cultural del territorio. La temática enlaza con la labor promotora del desarrollo y el liderazgo que las universidades han de realizar en su contexto referencial; además, de potenciar el rol y el compromiso del profesorado en esos procesos. Durante los dos años y medio transcurridos en la materialización del proyecto, la labor realizada en 12 escuelas dependientes del Departamento de Educación de la municipalidad de Coyhaique ha sido intensa por la cantidad de acciones y actividades desarrolladas, fructífera en relación al proceso de desarrollo de colaboración interuniversitaria de la Universidad de Talca y la Universidad Autónoma de Barcelona y muy satisfactoria en relación a los procesos iniciados y a los indicadores de éxito ya alcanzados. La aportación recoge reflexiones sobre la temática y realizaciones de los doce centros. La proyección última es la de mejorar la capacidad de los centros para promover los cambios que posibiliten aumentar su calidad educativa e, indirectamente, mejorar el desarrollo social a partir de una mejor cualificación de sus recursos humanos y de una mayor implicación social de los promotores del mismo

Assessing Groundwater Potential in a Mid-Mountain Dryland Area of North-Central Chile through Geospatial Mapping

This study utilized the Random Forest (RF) algorithm to assess groundwater potential (GWP) in the mid-mountain region of the Coquimbo region, north-central Chile. A comprehensive evaluation of twenty-one factors, primarily derived from Digital Elevation Models (DEM) and satellite data, was conducted against a database of 3822 groundwater discharge points. The majority of them consisted of shallow wells with relatively low yields. The main objective was to develop a groundwater potential (GWP) map for the study area. Among the factors considered, six variables, including two anthropogenic factors (distance to roads and presence of agricultural communities) and four natural factors (slope, elevation, concavity, and ruggedness index), were identified as the most influential indicators of GWP. The RF approach demonstrated excellent performance, achieving an Area Under the Curve (AUC) value of 0.95, sensitivity of 0.88, specificity of 0.86, and kappa coefficient of 0.74 in the test set. The majority of the study area exhibited low GWP, while only 14% of the area demonstrated high or very high GWP. In addition to providing valuable guidance for future hydrogeological investigations in the region, the GWP map serves as a valuable tool for identifying the areas that are most vulnerable to water shortages. This is particularly significant, as the region has been severely affected by extended drought, making water supply a critical concern

Tectonic events reflected by palaeocurrents, zircon geochronology, and palaeobotany in the Sierra Baguales of Chilean Patagonia

The Sierra Baguales, situated north of the Torres Del Paine National Park in the Magallanes region of southern Chile, shows awell-exposed stratigraphic sequence ranging fromthe Late Cretaceous to late Pliocene, which presents a unique opportunity to study the evolution of sedimentological styles and trends, palaeoclimate changes, and tectonic events during this period. The depositional environment changed froma continental slope and shelf during the Cenomanian-Campanian (Tres Pasos Formation) to deltaic between the Campanian-Maastrichtian (Dorotea Formation) and estuarine in the Lutetian-Bartonian (Man Aike Formation). During the Rupelian, a continental environment with meandering rivers and overbank marshes was established (Río Leona Formation). This areawas flooded in the early Burdigalian (Estancia 25 deMayo Formation) during the Patagonian Transgression, but emerged again during the late Burdigalian (Santa Cruz Formation). Measured palaeocurrent directions in this Mesozoic-Cenozoic succession indicate source areas situated between the northeast and east-southeast during the Late Cretaceous, east-southeast during the middle Eocene, and southwest during the early Oligocene to earlyMiocene. This is confirmed by detrital zircon age populations in the different units,which can be linked to probable sources of similar ages in these areas. The east-southeastern provenance is here identified as the Antarctic Peninsula or its northeastern extension, which is postulated to have been attached to Fuegian Patagonia during the Eocene. The southwestern and western sources were exhumed during gradual uplift of the Southern Patagonian Andes, coinciding with a change from marine to continental conditions in the Magallanes-Austral Basin, as well as a decrease in mean annual temperature and precipitation indicated by fossil leaves in the Río Leona Formation. The rain shadow to the east of the Andes thus started to develop here during the late Eocene- early Oligocene (~34Ma), long before the “Quechua Phase” of Andean tectonics (19–18Ma) that is generally invoked for its evolution at lower latitudes

Magnetometric Surveys for the Non-Invasive Surface and Subsurface Interpretation of Volcanic Structures in Planetary Exploration, a Case Study of Several Volcanoes in the Iberian Peninsula

Volcanoes are typical features of the solar system that offer a window into the interior of planets. Thus, their study can improve the understanding of the interiors and evolution of planets. On Earth, volcanoes are monitored by multiple sensors during their dormant and active phases. Presently, this is not feasible for other planets’ volcanoes. However, robotic vehicles and the recent technological demonstration of Ingenuity on Mars open up the possibility of using the powerful and non-destructive geophysical tool of magnetic surveys at different heights, for the investigation of surfaces and subsurfaces. We propose a methodology with a view to extract information from planetary volcanoes in the short and medium term, which comprises an analysis of the morphology using images, magnetic field surveys at different heights, in situ measurements of magnetic susceptibility, and simplified models for the interpretation of geological structures. This methodology is applied successfully to the study of different examples of the main volcanic zones of the Iberian Peninsula, representative of the Martian intraplate volcanism and similar to Venus domes, as a preparatory action prior to the exploration of the rocky planets’ surfaces

Depósitos estuarinos en la Formación Río Baguales (Chattiano-Aquitaniano), Provincia de Magallanes, Chile)

Very little work has been done on the stratigraphy and sedimentology of the upper Oligocene-Lower Miocene Río Baguales Formation in the Magallanes Province of southern Chile since its original definition in 1957. A detailed stratigraphic section of the upper part of the formation exposed west of the Baguales River is presented, with an interpretation of depositional environments. This indicates a prograding shoreline in which estuary mouth, middle estuary (lagoon) and bay head delta facies are represented. Large-scale delta slope foresets indicate progradation towards the north and northwest, whereas southeast-directed cross-beds on the delta front probably suggest wave action. The general sequence reflects a gradual sea-level fall largely counteracted by tectonic subsidence, which provided the ne- cessary accommodation space for thick tidal flat and subtidal deposits to accumulate. A longer period of transgression towards the top of the succession may be related to a rise in sea-levelHay muy pocos trabajos sobre la estratigrafía y sedimentología de la Formación Río Baguales del Oligoceno superior-Mioceno inferior en la Provincia de Magallanes del sur de Chile, luego de su primera definición en 1957. Se presenta un perfil estratigráfico detallado de la parte superior de la formación al oeste del río Baguales, con una interpretación de los ambientes de depositación. Se identificó una costa progradante con facies de boca de estuario, medio de estuario (laguna) y delta de cabecera. Las grandes capas frontales del talud deltaico indican progradación hacia el norte y noroeste, mientras que la presencia de laminación cruzada inclinada hacia el sureste sugiere la acción de oleaje. La sucesión en general refleja una caída gradual del nivel del mar, acompañada por subsidencia tectónica con la creación del espacio de acomodación necesario para la acumulación de potentes facies mareales y submareales. Un período de transgresión hacia la parte superior de la sucesión indica una subida del nivel del mar o una aceleración en la tasa de subsidencia tectónica, seguida por una regresión mayor que comenzó alrededor de 23,3 Ma, probablemente coincidente con la apertura del Pasaje de Drake y el crecimiento de la calota de hielo de la Antártica del est