29 research outputs found
The central Fuegian fold and thrust belt in Tierra del Fuego: Strike‐slip tectonics superimposed onto compressional deformation
No full textThe boundary between South America and Scotia plates was established during Neogene times when a wrench tectonic regime was developed along the central area of Tierra del Fuego. This boundary includes the Magallanes–Fagnano fault system: a regional diffuse deformation zone, which involves the development of the satellite Yehuin–Chepelmut fault zone and a series of pull-apart basins overprinting the Fuegian fold and thrust belt. The analysis of regional seismic lines allowed to reconstruct and recognize the structure of the external fold and thrust belt. The interpreted structures were integrated into a regional transect and a 3D block diagram that display the different structural domains and, mainly, the wrench deformation associated with the Magallanes–Fagnano fault system. Geophysical data from gravity and magnetic anomaly maps provided further support for the location and development of the pull-apart basins along the plate boundary. The deformation of the external fold and thrust belt is characterized by an imbricated fan system with a Paleogene detachment surface, which was later cut across by the Yehuin–Chepelmut fault zone and the Magallanes–Fagnano fault system.Fil: Lozano, Jorge Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; ArgentinaFil: Bran, Donaldo Mauricio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Peroni, Javier Ignacio. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lodolo, Emanuele. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Menichetti, Marco. Università Degli Studi Di Urbino Carlo Bo; ItaliaFil: Cerredo, Maria Elena. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Tassone, Alejandro Alberto. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentin
The Cerro Guanaco mass movements: A geophysical and morphometric approach on a megalandslide in the Fuegian Andes (Southern Patagonia)
No full textThe Fuegian Andes, in the southernmost part of South America, are characterized by a relatively young deglacial
landscape, where the glacial erosive relief is strongly influenced by regional-scale geological structures, resulting
in deep longitudinal valleys with steeply dipping hillslopes. The rock-slope stability response to receding ice
masses and the contribution of the gravitational processes in landscape evolution of the southernmost Andes,
however, have not been assessed so far. The remoteness of the region, comprising a mountainous area hardly to
access and piedmont and valley floors densely covered by forest, peatbogs or water bodies might partly explain
the lack of such studies. Therefore, the objective of this contribution is to document for the first time the
occurrence of massive slope failures in the Fuegian Andes using a multidisciplinary approach. This involves the
use of indirect methods such as applied geophysics and landscape morphometrics. The southwest-facing slope of
Cerro Guanaco, near Ushuaia, hosts several slope failures, but a massive failure stands out. The morphostructural
approach allowed the geometrical description of the main dimensional characteristics of the first megalandslide
recognized in the Fuegian Andes, which involved almost 1,2 km3 of material. On the other hand, the geophysical
data has proved valuable in estimating the depth and characteristic of the buried detachment surface. The slope
failure consisted of an initial translational movement followed by secondary slides and was developed shortly
after the glacier recession. The gravitational processes represent an important element in the Fuegian deglacial
landscape evolution
Shallow architecture of Fuegian Andes lineaments based on Electrical Resistivity Tomography (ERT). Evidences of transverse extensional faulting in the central Beagle Channel area
No full textThe southern foothills of the Fuegian Andes are bounded by the Beagle Channel (BC), a conspicuous
E-W longitudinal basin, controlled by a large transcurrent fault system, which extends from the Atlantic to the Pacific
Ocean. The northern shore of the Beagle Channel’s central segment is characterized by several E-W oriented valleys,
parallel to the main basin, which are interspersed with a series of oblique NW trending lineaments that extend across the
mountain belt. A geoelectrical survey was carried out in order to investigate the shallow architecture of such sets of linear morphologies. The principal E-W lineament system was characterized by conspicuous sub-vertical resistivity contrasts,
interpreted as fractured zones associated with fault strands of the main strike-slip Beagle Channel system, whereas the
oblique NW-SE trending set of lineaments revealed slightly different resistivity patterns, with vertical displacements
and less abrupt contrasts. These resistivity patterns, in combination with the widespread occurrence of normal faulting
in the area, allowed to infer an extensional control over the oblique depressions. These morphological features were
related to oblique transverse faults that segment two sub parallel E-W fault systems. The oblique faults were probably
developed along inherited structural anisotropies and can be extended well beyond the BC shoreline to the NW. Both
geophysical and field evidence suggest a post-glacial deformation along the area
Estudio geofísico del sector central del canal Beagle, Tierra del Fuego
No full textEl presente trabajo final de licenciatura comprende un estudio geológico-geofísico aplicado a analizar los procesos sedimentarios cuaternarios que tuvieron lugar en el sector central del canal Beagle. Además, se analizan los procesos de remoción en masa, rasgos de corrientes de fondo, evidencias de actividad neotectónica y presencia de gas somero en las líneas sísmicas investigadas. El trabajo se basa en el procesamiento, correlación e interpretación de datos de sísmica de reflexión preexistentes, tomados por el grupo de investigación en el área, junto con la adquisición de nuevos datos de perfiles de subfondo tomados durante el trabajo de campo realizado para este TFL. A partir de la integración de los datos acústicos se realiza primero una caracterización sismo-estratigráfica del relleno del sector central del canal Beagle, definiendo 5 unidades sísmicas. Luego, se interpretan los procesos depositacionales y paleoambientes asociados a las unidades identificadas en la sísmica, facies glacigénicas, glacilacustres, glacimarinas y marinas. Por otra parte, se caracterizan diferentes subfosas, se presentan evidencias de neotectónica, así como de procesos de remoción en masa y corrientes de fondo asociadas. Además, se aborda la presencia de gas somero y la caracterización de las distintas manifestaciones sismoacústicas registradas, junto con la generación de un mapa de su distribución espacial del gas en el área de estudio.Fil: Feller, Julieta. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Active faulting in the Beagle Channel (Tierra del Fuego)
No full textIn Tierra del Fuego, the Magallanes-Fagnano
Fault System (MFFS) accommodates
a significant portion of the relative motion between the South America and Scotia
plates. However, it remains unclear whether some of the deformation is partitioned
southwards, along the Beagle Channel Fault System (BCFS). In this paper, high-resolution
seismic reflection profiles were used to identify fault-related
ruptures in
the submerged Quaternary sediments of the Beagle Channel. Some faults reach the
seafloor, affecting marine sediments, indicating they are Holocene in age. The correlation
with outcrop data and lineaments mapped onshore suggests the post-glacial
reactivation
of two structures: the E-W
striking BCFS and the NW-SE-
trending
Lapataia
Fault Zone (LFZ). Whereas the BCFS displays along-strike
variation in throw, the LFZ
shows significant normal displacements. These results imply that deformation occurs
in a wider and more complex manner than previously thought and highlight the need
for a thorough hazard assessment of the area
Geología y estructura de los alrededores del Paso de las Nubes, Andes Norpatagónicos, Provincia de Río Negro
No full textEl presente resumen tiene como objetivo realizar un estudio geológico y estructural al este del monte Tronador, en el sector central de los Andes Norpatagónicos, entre los 41º08´ y los 41º11´ de latitud S. A la latitud delpresente estudio el orógeno andino puede segmentarse en tres dominios: uno occidental, uno central y uno oriental (Bechis et al. 2015). El sector occidental está caracterizado por la presencia de la zona de falla LiquiñeOfqui, de cinemática transcurrente dextral (Lavenu y Cembrano 1999; Rosenau et al. 2006). El central, en el cual se localiza la zona objeto de análisis, presenta un estilo estructural de piel gruesa constituido por bloquesde basamento levantados por fallas inversas de despegue profundo (Ramos y Cortés 1984; Kley et al. 1999; Giacosa y Heredia 2004). Actualmente existen dos posturas vigentes sobre el mecanismo mediante el cual se formaron los Andes Norpatagónicos a estas latitudes, las cuales no son necesariamente excluyentes: una de ellas plantea un régimen compresivo (Ramos y Cortés 1984; Giacosa y Heredia 2004), mientras que la otra sostiene un estilo estructural transpresivo (Diraison et al. 1998). Los objetivos del trabajo consistieron en el mapeo y análisis de las unidades litológicas aflorantes y la caracterización cinemática y cronológica de las estructuras halladas elaborando un modelo conceptual que permitieraexplicar la evolución de la deformación y el estilo estructural dominante de la zona de estudio.Fil: Olaizola, Ezequiel Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Diversidad Cultural y Procesos de Cambio. Universidad Nacional de Río Negro. Instituto de Investigaciones en Diversidad Cultural y Procesos de Cambio; ArgentinaFil: Bechis, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Diversidad Cultural y Procesos de Cambio. Universidad Nacional de Río Negro. Instituto de Investigaciones en Diversidad Cultural y Procesos de Cambio; ArgentinaFil: Yagupsky, Daniel Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Bran, Donaldo Mauricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaXX Congreso Geológico ArgentinoSan Miguel de TucumánArgentinaAsociación Geológica Argentin
Holocene seismic stratigraphy of the southern arms of Lago Argentino
No full textLago Argentino hosts various calving glaciers, including the famous Perito Moreno. Although the onland Holocene glacier dynamics is rather well constrained, the paleoenvironments developed in association with a retreating ice front remain largely unknown. A detailed analysis of high-resolution seismic reflection profiles acquired in the southern arms of Lago Argentino has allowed the identification of several unconformities within the lacustrine sedimentary infill. Four seismostratigraphic sequences have been identified in Brazo Rico and three in Brazo Sur. These sequences are separated by three erosive unconformities in Brazo Rico and two in Brazo Sur, and reflect the sedimentation of a pre-Holocene deep basin in a proglacial lake. The older unconformities are associated with instability events within the basin which triggered several mass movements, possibly related to enhanced seismic activity. The younger erosive unconformities were correlated with the “Pearson 1a/Frias 1 advance”, the major glacier advance in the Holocene of the Lago Argentino Basin. This research highlights the importance of studying the glaciolacustrine sediments, representing decisive records of the glacial history and palaeoclimate, which could help unveiling the factors controlling glacier dynamics in the basin and reconstructing the deglacial landscape of the area.Fil: Lozano, Jorge Gabriel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Bran, Donaldo Mauricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; ArgentinaFil: Lodolo, Emanuele. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Tassone, Alejandro Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; ArgentinaFil: Vilas, Juan Francisco A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentin
The submerged footprint of Perito Moreno glacier
No full textPerito Moreno is the most famous calving glacier of the South Patagonia Icefield, the largest temperate glacier system of the Southern Hemisphere. Unlike most of the glaciers in the region that have strongly retreated in recent decades, the position of Perito Moreno glacier front remained relatively unchanged in the last century. However, earliest photographic documents show that, at the end of the nineteenth century, the front was ca. 800 m behind the current position. There is no reliable information about the positions of the Perito Moreno front in earlier times. Here we show evidence of two subaqueous moraine systems both in the Canal de Los Témpanos and in the Brazo Rico, the two arms of Lago Argentino along which Perito Moreno glacier has flowed over time. These moraines, identified for the first time in the Canal de Los Témpanos from bathymetric and high-resolution seismic profiles, mark the position of the largest glacier advance, tentatively correlated with the moraines of the “Herminita advance” identified and dated onland. We interpret these bedforms as the evidence of the most pronounced advance of Perito Moreno glacier during the mid-Holocene cooling event that characterized this sector of the Southern Hemisphere. This study highlights the importance of subaqueous glacial bedforms, representing decisive records of the glacial history and palaeoclimate, which could help unveiling the origin of the different behavior of glaciers like Perito Moreno that in a warming climate are relatively stable.Fil: Lodolo, Emanuele. Istituto Nazionale di Oceanografa e di Geofsica Sperimentale ; ItaliaFil: Donda, Federica. Istituto Nazionale di Oceanografa e di Geofsica Sperimentale ; ItaliaFil: Lozano, Jorge Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Baradello, Luca. Istituto Nazionale di Oceanografa e di Geofsica Sperimentale ; ItaliaFil: Romeo, Roberto. Istituto Nazionale di Oceanografa e di Geofsica Sperimentale; ItaliaFil: Bran, Donaldo Mauricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Tassone, Alejandro Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentin
Rewilding Patagonia : in the Wild Patagonia Reserve Network, guanacos, choiques, and pumas will roam free
No full textThe Patagonian steppe of Argentina is a vast area-almost 750,000 square kilometers- of arid plains and scrub ecosystems in the rain shadow of the southern Andes, at the tip of South America. The name "Patagonia" evokes romantic images of a windy wilderness at the end of the Earth. Indeed, a recent article in National Geographic described Patagonia as the "wild, wild south," and Conservation International has identified the region as a wilderness and one of "Earth's Last Wild Places" based on its size, low population density, and purported lack of change in vegetation. But what is a wilderness or a wild place? It's an area dominated by natural processes, home to a complete life community, and, for the most part, undisturbed by human activity. Although Patagonia is vast and sparsely populated, and its climate and topography are as harsh and wild as ever, we argue that human activities over the past 100 years have deeply altered the structure and composition of Patagonian wildlife and vegetation communities, and that most of the region is no longer truly wild.Fil: Walker, Susan. Provincia del Neuquén. Subsecretaría de Producción y Recursos Naturales. Centro de Ecología Aplicada del Neuquén; Argentina. Wildlife Conservation Society; ArgentinaFil: Novaro, Andres Jose. Provincia del Neuquén. Subsecretaría de Producción y Recursos Naturales. Centro de Ecología Aplicada del Neuquén; Argentina. Wildlife Conservation Society; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Funes, Martín. Provincia del Neuquén. Subsecretaría de Producción y Recursos Naturales. Centro de Ecología Aplicada del Neuquén; ArgentinaFil: Baldi, Ricardo. Wildlife Conservation Society; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Chehébar, Claudio. Administración de Parques Nacionales. Delegación Regional Patagonia; ArgentinaFil: Ramilo, Eduardo Juan. Administración de Parques Nacionales. Delegación Regional Patagonia; ArgentinaFil: Ayesa, Javier Alejandro. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Bran, Donaldo Mauricio. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vila, Alejandro. Wildlife Conservation Society; ArgentinaFil: Bonino, Never Antonio. Instituto Nacional de Tecnología Agropecuaria; Argentin
Linking ecosystem resistance, resilience, and stability in steppes of North Patagonia
No full textThe main objective of an ecosystem sustainable management is to preserve its capacity to respond and adapt to current disturbances and/or future changes, and maintain the provision of environmental goods and services. Two very important properties linked to this objective are the ecosystem resilience and resistance to disturbance factors. The Structural–Functional State and Transition Model (SFSTM) is a conceptual framework that allows evaluating the ecosystem resilience and resistance based on structural and functional attributes. On the other hand, the Landscape Functional Analysis (LFA) presents a method to assess the rangeland “health” based on structural vegetation and soil indicators, creating indexes to evaluate the ecosystem functional integrity. The aim of this study is to integrate LFA and SFSTM as an approach to help validate indicators and indexes associated with the resistance, resilience, and stability of a temperate rangeland ecosystem. States and transitions model for a shrubby-grasses steppe of the Western Patagonian District was used as a reference system. Changes in vegetation structure, soil surface, and loss of soil due to erosion were determined in sites with different grazing histories. Based on the SFSTM, we assessed the relationships between ecosystem structural changes with the recruitment process of the plant community and ecosystem integrity indexes (sensu LFA). Our results indicate that the decrease in the recruitment process, related to different grazing histories, was associated with a loss of ecosystem functional integrity. This was associated to a decrease in the ability to retain, store, and use rain water, and also in nutrient cycling. This suggests that the integration of the LFA methodology to the SFSTM can be used for indexes validation, which in turn allows the identification of critical thresholds associated with ecosystem resilience loss. Finally, throughout the integration of indicators of LFA into SFSTM, we established relationships between ecosystem resistance, resilience, and stability in response to a disturbance factor (e.g. overgrazing). Thus, we used this information to define states in stable, unstable, mixed-unstable, and indifferent-stable dynamic equilibriums. Our proposed approach provides a tool for ecosystem assessment regarding the identification of states that can be restored and those that might be more susceptible to degradation. Such information might help in the prevention of crossing a critical threshold and be used for sustainable management programs in rangelands.Fil: López, Dardo Rubén. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche; ArgentinaFil: Brizuela, Miguel Angel. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Willems, Priscila. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche; ArgentinaFil: Aguiar, Martin Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomia; ArgentinaFil: Siffredi, Guillermo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche; ArgentinaFil: Bran, Donaldo Mauricio. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche; Argentin
