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1
Hallam, A., L. Biró-Bagóczky, and E. Perez. "Facies analysis of the Lo Valdés Formation (Tithonian–Hauterivian) of the High Cordillera of central Chile, and the palaeogeographic evolution of the Andean Basin." Geological Magazine 123, no. 4 (July 1986): 425–35. http://dx.doi.org/10.1017/s0016756800033513.
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AbstractFacies descriptions and environmental interpretations are given for outstanding sections of marine Tithonian to Hauterivian strata in the High Cordillera of the central Chilean Andes. Comparisons are made with correlative strata in other regions in Chile, and with the Neuquén Basin of west central Argentina. The rich and partly endemic bivalve fauna, which has strong African affinities, shows no change up the stratigrapic sequence that cannot be related to local facies. Water depth is recognized as the main variable controlling the distribution of the bivalve and ammonite faunas. Utilizing data from both Chile and Argentina, a model is put forward for the late Jurassic to mid Cretaceous sequence whereby the facies distributions are accounted for by the interaction of global sea-level changes and regional tectonics in a shallow back-arc basin.
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Dott, Robert H., and Ian W. D. Dalziel. "Darwin the geologist in southern South America." Earth Sciences History 35, no. 2 (January 1, 2016): 303–45. http://dx.doi.org/10.17704/1944-6178-35.2.303.
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Charles Darwin was a reputable geologist before he achieved biological fame. Most of his geological research was accomplished in southern South America during the voyage of H.M.S. Beagle (1831–1836). Afterward he published four books and several articles about geology and coral atolls and became active in the Geological Society of London. We have followed Darwin's footsteps during our own researches and have been very impressed with his keen observations and inferences. He made some mistakes, however, such as appealing to iceberg rafting to explain erratic boulders and to inundations of the sea to carve valleys. Darwin prepared an important hand-colored geological map of southern South America, which for unknown reasons he did not publish. The distributions of seven map units are shown. These were described in his books wherein he also documented multiple elevated marine terraces on both coasts of South America. While exploring the Andean Cordillera in central Chile and Argentina, he discovered two fossil forests. Darwin developed a tectonic theory involving vertical uplift of the entire continent, which was greatest in the Andes where magma leaked up from a hypothetical subterranean sea of magma to form volcanoes and earthquakes. The theory had little impact and was soon eclipsed by theories involving lateral compression of strata. His and other contemporary theories suffered from a lack of knowledge about the earth's interior. Finally with modern plate tectonic theory involving intense lateral compression across the Andean Cordillera we can explain satisfactorily the geology so carefully documented by Darwin.
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Herrera, Sebastian, Luisa Pinto, Katja Deckart, Javier Cortés, and Javier Valenzuela. "Cenozoic tectonostratigraphic evolution and architecture of the Central Andes in northern Chile based on the Aquine region, Western Cordillera (19°-19º30’ S)." Andean Geology 44, no. 2 (May 31, 2017): 87. http://dx.doi.org/10.5027/andgeov44n2-a01.
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Martínez, F., A. Maksymowicz, H. Ochoa, and D. Díaz. "Geometry of the inverted Cretaceous Chañarcillo Basin based on 2-D gravity and field data – an approach to the structure of the western Central Andes of northern Chile." Solid Earth 6, no. 4 (December 3, 2015): 1259–76. http://dx.doi.org/10.5194/se-6-1259-2015.
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Abstract. This paper discusses an integrated approach that provides new ideas about the structural geometry of the NNE-striking, Cretaceous Chañarcillo Basin located along the eastern Coastal Cordillera in the western Central Andes of northern Chile (27–28° S). The results obtained from the integration of two transverse (E–W) gravity profiles with previous geological information show that the architecture of this basin is defined by a large NNE–SSE-trending and east-vergent anticline ("Tierra Amarilla Anticlinorium"), which is related to the positive reactivation of a former Cretaceous normal fault (Elisa de Bordos Master Fault). Moreover, intercalations of high and low gravity anomalies and steep gravity gradients reveal a set of buried, west-tilted half-grabens associated with a synthetic normal fault pattern. These results, together with the uplift and folding style of the Cretaceous synextensional deposits recognized within the basin, suggest that its structure could be explained by an inverted fault system linked to the shortening of pre-existing Cretaceous normal fault systems. Ages of the synorogenic deposits exposed unconformably over the frontal limb of the Tierra Amarilla Anticlinorium confirm a Late Cretaceous age for the Andean deformation and tectonic inversion of the basin.
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Charrier, Reynaldo, Lasafam Iturrizaga, Sébastien Carretier, and Vincent Regard. "Geomorphologic and Glacial Evolution of the Cachapoal and southern Maipo catchments in the Andean Principal Cordillera, Central Chile (34°-35º S)." Andean Geology 46, no. 2 (May 31, 2019): 240. http://dx.doi.org/10.5027/andgeov46n2-3108.
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We present here a reconstruction of the post late Miocene landscape evolution of the western slope of the Andean Cordillera Principal near 34°20’ S. We base our analysis on the available geological information, a morphological characterization of the landform assemblages in the Cachapoal and southern Maipo catchments, and the first 10Be exposure ages for moraines in this area. The Cachapoal drainage basin is characterized by a variety of morphological features, like an elevated low-relief surface, volcanoes and lava flows on valley slopes, U-shaped valley sections, roches moutonnées, and large glaciated areas. Different kinds of deposits have been included in the study, such as moraines, lacustrine and landslide deposits, and a well-developed system of fluvial terraces in the more distal part of the Cachapoal catchment. Landslides are mostly developed on rocks of the late Eocene-early Miocene Abanico Formation. and are less frequent in outcrops of the overlying, early to middle Miocene Farellones Formation. We estimate that the lowest end moraine in the Cachapoal catchment is located next to the locality Bocatoma Chacayes (~950 m altitude), though covered by a major landslide. No evidence exist for glacial deposits further down stream in this region. Lateral moraine ridges of the Cachapoal Glacier at Los Cerrillos yielded 10Be exposure ages of 20.3±2.9 and 21.9±5.3 ka that indicate they are associated with the Last Glacial Maximum (LGM). Holocene moraines exist next to all glacier tongues. Of particular interest in this region is the 12 km-long debris-covered Cachapoal Glacier, the longest valley glacier in the central Chilean Andes, and its distal and proximal moraine deposits. Two lateral moraines adjacent to the present-day Cachapoal Glacier yielded exposure average ages of 13.5±2.4 ka for the external ridge, indicating the Younger Dryas, and 3.8±0.8 ka for the internal ridge, an age that coincides with the 4.2 ka global climatic event that marks the beginning of the Meghalayan Age, at the end of the Holocene. The large size of this moraine on both sides of the ice tongue indicates the great development of the glacier at that time. Some of these ages coincide with ages obtained further north in the Maipo drainage basin, at the latitude of Santiago, and in the eastern flank of the cordillera, however, no pre-LGM deposits were found here, unlike the other mentioned regions. This difference together with the much lower altitude of the LGM moraine deposits in the study region suggests that the Cachapoal catchment is a transition zone to a more humid region further south, and indicates the great need for further reconnaissance and dating of glacial deposits in this Andean region. Our analysis of the geomorphological evolution is consistent with incision start for the Cachapoal Valley in latest Miocene. In this process, glacier incision was apparently not much effective until mid-Pleistocene time, when volcanism was active in the higher regions of the mountain range covering areas not yet incised, whereas in the western Principal Cordillera lavas flowed in deeply incised valleys. Pleistocene glaciers deepened and shaped the already incised valleys, which are presently mostly occupied by rivers.
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Barrett, Bradford S., RenéD Garreaud, and Mark Falvey. "Effect of the Andes Cordillera on Precipitation from a Midlatitude Cold Front." Monthly Weather Review 137, no. 9 (September 1, 2009): 3092–109. http://dx.doi.org/10.1175/2009mwr2881.1.
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Abstract The effects of the Andes Cordillera, the major mountain range in South America, on precipitation patterns of baroclinic systems approaching from the southeast Pacific remain largely unstudied. This study focuses on a case in late May 2008 when an upper-level trough and surface cold front produced widespread precipitation in central Chile. The primary goal was to analyze the physical mechanisms responsible for the structure and evolution of the precipitation. Weather Research and Forecasting (WRF) model simulations indicate that as an upper-level trough approached central Chile, midtropospheric flow below 700 hPa was blocked by the high topography and deflected poleward in the form of a barrier jet. This northerly jet had wind maxima in excess of 15 m s−1, was centered around 925 hPa, and extended westward 200 km from the mountains. It intersected the cold front, which approached from the south near the coast, thereby increasing convergence along the frontal surface, slowing its equatorward progress, and enhancing rainfall over central Chile. Another separate region of heavy precipitation formed over the upwind slopes of the cordillera. A trajectory analysis confirmed that the barrier jet moved low-level parcels from their origin in the moist southeast Pacific boundary layer to the coast. When model topography was reduced to twenty percent of its original height, the cold front advanced more rapidly to the northeast, generated less precipitation in central Chile between 33° and 36°S, and produced minimal orographic precipitation on the upwind Andean slopes. Based on these findings, the high topography appears responsible for not only orographic precipitation but also for substantially increasing precipitation totals over the central coast and valley.
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Bonini, Ricardo A., Gabriela I. Schmidt, Marcelo A. Reguero, Esperanza Cerdeño, Adriana M. Candela, and Natalia Solís. "First record of Toxodontidae (Mammalia, Notoungulata) from the late Miocene–early Pliocene of the southern central Andes, NW Argentina." Journal of Paleontology 91, no. 3 (February 21, 2017): 566–76. http://dx.doi.org/10.1017/jpa.2016.160.
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AbstractA new species of toxodontid notoungulate, Xotodon maimarensis n. sp., is described from the Maimará Formation (late Miocene–early Pliocene), Jujuy Province, northwestern Argentina. This is the first record of a toxodontid from the Eastern Cordillera. The specimen is housed at the Museo de Geología, Mineralogía y Paleontología, Instituto de Geología y Minería de la Universidad Nacional de Jujuy. It consists of an incomplete mandible preserving the right mandibular ramus with part of the dental series, partially preserved symphysis with all the incisors, and a small portion of the left ramus without teeth. The following characters distinguish it as a new taxon: symphysis long and narrow with slight divergence of its lateral borders; strong procumbence of lower incisors and deeply implanted i3; chin angle lower than in X. major and X. cristatus and bulging labial keel limiting strong lateral concavities. Comparative analysis in the context of the recently revised Neogene Toxodontidae indicates that the Maimará specimen shares mandibular features and dental characters with Xotodon and Mixotoxodon, differing from the latter by the more upraised symphysis. The phylogenetic position of Xotodon maimarensis n. sp. supports the taxonomic interpretation of the studied specimen as a new species of Xotodon. This new Toxodontidae increases the knowledge of the diversity and radiation of this group of notoungulates in northwest Argentina.
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WILSON, RYAN, SEBASTIAN H. MERNILD, JEPPE K. MALMROS, CLAUDIO BRAVO, and DANIELA CARRIÓN. "Surface velocity fluctuations for Glaciar Universidad, central Chile, between 1967 and 2015." Journal of Glaciology 62, no. 235 (July 13, 2016): 847–60. http://dx.doi.org/10.1017/jog.2016.73.
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ABSTRACTFor the Andes Cordillera, where observed mass-balance records are sparse, long-term glacier velocity measurements potentially represent a useful tool for assessing glacier health. Utilising manual and automatic feature-tracking techniques applied to Corona, Landsat and ASTER satellite imagery, this paper presents surface velocity fluctuations for Glaciar Universidad between 1967 and 1969, and 1985 and 2015, the longest such time series available for the Andes Cordillera, outside Patagonia. This time series reveals an increase in the surface velocities of the main glacier trunk between 1967 and 1987 (~90%) followed by a deceleration between 1987 and 2015 (~80%), with ice velocities observed between 2014 and 2015 possibly representing a 48 a low. In response to the surface velocity fluctuations, the glacier front advanced between 1985 and 1992 (cumulative change of 137 ± 14 m), and again to a lesser magnitude during the 1996–98 and 2004–08 periods. Although having exhibited possible surge behaviour during the 1940s, the synchrony of the glacier changes presented for Glaciar Universidad with those reported for nearby glaciers, suggests that this glacier is responding to climatic trends. If the above scenario is true, the results indicate a general pattern of increasingly negative glacier mass-balance conditions since the late 1980s.
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Sarricolea, Pablo, Mariajosé Herrera Ossandon, and Cristóbal Araya Escobar. "Análisis de la concentración diaria de las precipitaciones en Chile central y su relación con la componente zonal (subtropicalidad) y meridiana (orográfica)." Investigaciones Geográficas, no. 45 (August 21, 2013): 37. http://dx.doi.org/10.5354/0719-5370.2013.27595.
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Este artículo analiza la distribución espacial y temporal de la irregularidad de las precipitaciones diarias en una franja zonal de la región central de Chile (32°50’S-34°12’S), mediante el índice de concentración (CI). En total se calculó el CI para un total de 16 estaciones meteorológicas, en el período 1965-2010. El propósito fue generar una regionalización climática basada en un índice diario que mide la irregularidad de las precipitaciones. Teóricamente, se han ensayado dos hipótesis:la primera propone que el CI disminuye de Norte-Sur, asociado a la componente Subtropicalidad; la segunda señala el efecto que tiene la orografía sobre el CI, provocando una reducción del índice desde la depresión intermedia a la Cordillera de los Andes, con un gradiente decreciente Oeste-Este. Los resultados alcanzados no dan cuenta de una reducción hacia el sur como era de esperar, pero sí confirma de manera clara la disminución del CI hacia la Cordillera de la Costa y los Andes.
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Hall, B. L., G. Denton, T. Lowell, G. R. M. Bromley, and A. E. Putnam. "Retreat of the Cordillera Darwin icefield during Termination I." Cuadernos de Investigación Geográfica 43, no. 2 (September 15, 2017): 751. http://dx.doi.org/10.18172/cig.3158.
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During the last glaciation, the Cordillera Darwin icefield expanded northward toward the Straits of Magellan, eastward across Isla Grande de Tierra del Fuego and through Canal Beagle, and south and west across the numerous islands of southernmost Chile. Deglaciation commenced at ~18 ka during Termination I. Alpine glaciers in the Fuegian Andes also likely retreated at that time. Radiocarbon ages from the interior regions of Cordillera Darwin suggest ice in at least some locations had retreated close to its present-day limit as early as ~16.5 ka. The most likely cause for such rapid ice retreat was rising atmospheric temperatures at the start of Termination I.
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Mernild, Sebastian H., Glen E. Liston, Christopher A. Hiemstra, Jacob C. Yde, James McPhee, and Jeppe K. Malmros. "The Andes Cordillera. Part II: Rio Olivares Basin snow conditions (1979-2014), central Chile." International Journal of Climatology 37, no. 4 (July 20, 2016): 1699–715. http://dx.doi.org/10.1002/joc.4828.
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Bonilla Rivera, Pablo Enrique. "Investigación fitoquímica, farmacológica y de toxicidad DL50 de Ephedra Americana Pinco-Pinco." Ciencia e Investigación 2, no. 1 (June 14, 1999): 27–43. http://dx.doi.org/10.15381/ci.v2i1.4404.
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Una yerba que crece a lo largo de la Cordillera de los Andes, denominada por los nativos Pinco-Pinco, y de amplio uso medicinal en la zona andina del Perú, en la altiplanicie de Bolivia y a lo largo de la cordillera andina de Argentina y Chile, cuyo nombre científico es Ephedra americana, es especie vegetal objeto de la presente investigación.En nuestro país esta especie crece abundantemente en el departamento de Arequipa, en el balneario de Jesús, en el camino a la Laguna de Salinas en faldas del nevado Pichu-Pichu.También crece en forma abundante en el Cusco. La muestra vegetal del presente estudio fue ubicada y recolectada en la ciudad de Calca, Cusco.
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Ward, D., R. Thornton, and J. Cesta. "Across the Arid Diagonal: deglaciation of the western Andean Cordillera in southwest Bolivia and northern Chile." Cuadernos de Investigación Geográfica 43, no. 2 (September 15, 2017): 667. http://dx.doi.org/10.18172/cig.3209.
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Here we review published cosmogenic records of glaciation and deglaciation from the western cordillera of the arid subtropical Andes of northern Chile and southwest Bolivia. Specifically, we examine seven published studies describing exposure ages from moraines and glaciated bedrock spanning the glaciological Arid Diagonal, the region of the dry Andes where there is no clear evidence for glaciation over at least the last global glaciation. We also present new cosmogenic 36Cl exposure ages from two previously undated sets of moraines in the deglaciated region near 22ºS. Taken together, these records indicate that the most extensive regional glaciation occurred ca. 35-45 ka, followed by slow, punctuated retreat through the global last glacial maximum, and rapid retreat after ~15-17 ka. In the vicinity of the large Altiplanic lakes that existed during the late glacial stage, the 15-17 ka moraines overrode the earlier moraines, whereas elsewhere regionally, on both sides of the Arid Diagonal, late glacial wet periods are represented only by less-prominent moraines in more retracted positions.
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Laborías, Alexis Rodrigo. "La controversia por el vertedero de residuos en la Cordillera de los Andes. Un estudio de caso acerca de la responsabilidad internacional por daño transfronterizo." Anuario Mexicano de Derecho Internacional 1, no. 21 (March 24, 2021): 565. http://dx.doi.org/10.22201/iij.24487872e.2021.21.15603.
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El artículo analiza la controversia entre Argentina y Chile, con motivo del descubrimiento de un vertedero de residuos en la Cordillera de los Andes, originado por la actividad de una empresa minera chilena, que arrojaba el material en desuso en el territorio argentino. El conflicto es estudiado a la luz de las reglas en materia de responsabilidad internacional y teniendo en cuenta los mecanismos de solución de disputas a los que recurren los Estados ante un hecho de contaminación transfronteriza.
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A. Drake, Lawrence, and Estela Minaya Ramos. "The propagation of Love and Rayleigh waves in the Andean Region." Geofísica Internacional 35, no. 3 (July 1, 1996): 273–84. http://dx.doi.org/10.22201/igeof.00167169p.1996.35.3.462.
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El patrón distintivo desde la fuente sísmica de un campo irradiado de ondas sísmicas se modifica profundamente al pasar por una región irregular como la Cordillera de los Andes de América del Sur. La onda Lg guiada por la corteza útil en la discriminación de fuentes sísmicas, pero, aun para una sola fuente, las amplitudes de ondas de periódo corto como Lg pueden variar significativamente. La Cordillera de los Andes de Bolivia forma una parte de la cadea de los Andes, que se originó en los dos principales ciclos orogénicos del Fanerozoico, un Ciclo Preandino Precámbrico-Paleozoico Superior y el Ciclo Andino Mesozoico-Cenozoico. Durante el último Ciclo, cuatro sistemas del arco magmático se desarrollaron sucesivamente hacie el este: un arco Jurásico-Cretácico Temprano en la Cordillera Costera de Chile, un arco Cretácico Medio en el Valle Longitudinal de Chle, un arco Cretácico Tardío-Paleogénico en la Precordillera Chilena y el arco Mioceno-Holoceno en la Cordillera Occidental (Omarini et al., 1991; Dorbath et al., 1993; Scheuber et al., 1994). En la región del Cabalgamiento Andino Principal entre la Cordillera Oriental (o Real) y las Sierras Subandinas en Bolivia septentrional, hay superposición de aproximadamente 230 km de edad Neogena (Roeder, 1988). Las areniscas cloríticas Permicas marinas cerca de Copacabana sobre el Lago Titicaa y las diamicititas, areniscas, cuarcitas y lutitas Ordovícico.Silúricas apretadamente plegadas, expuestas abundantemente en los cortes del camino entre Cochabamba y Caracollo, se encuetran a elevaciones desde 3800 m a 4500 m sobre el nivel del mar. El sistema de fallas de la Cordillera Real, en el borde sudoccidental, marca un límite subvertical, con buzamiento al sudoeste, que separa dos unidades de velocidad contrastante hasta una profundidad de 140 km. La profundiad de Moho debajo del Altiplano fue encontrada por Dorbath et al. (1993) aproximadamente a 60 km y, debajo de la Cordillera Real, aproximadamente a 50 km. Más al sur, a través del Sur de Bolivia y Norte de la Argentina, Wigger et al. (1994) encontraton que la profundidad al Moho debajo del Altiplano es aproximadamente de 72 km y, debajo de la Cordillera Real aproximadamente a 65 km. La propagación de las ondas de Love y de Rayleigh de periódo corto, a lo largo de un perfil que atraviesa estas unidades del Altiplano y de la Cordillera Real de Bolivia septentrional, ha sido analizada por el método de elementos finitos. Un resultado preliminar es que, sin tener en cuenta la absorción, a un periódo de 2 s, 91.69% de la energía del modo fundamental de la onda Love y 98.60% de la energía del modo fundamental de la onda Rayleigh son transmitidos.
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Vargas, Ximena. "Corrientes de detritos en la quebrada de Macul, Chile. Estudio de caudales máximos." Ingeniería del agua 6, no. 4 (December 31, 1999): 341. http://dx.doi.org/10.4995/ia.1999.2798.
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Se analiza la ocurrencia de corrientes de detritos en una cuenca andina en la que no se dispone de información fluviométrica y que se desarrolla en los primeros contrafuertes de la Cordillera de Los Andes, en una zona cercana a la ciudad de Santiago, Chile. Se estiman los caudales líquidos asociados a los mayores eventos históricos que de acuerdo a la literatura pueden clasificarse como flujos de barro o de detritos y se analiza la forma tradicional de determinación de caudales de diseño en cuencas pluvionivales. Dada la incidencia que estos eventos tienen sobre la población de zonas aledañas al cauce, se evalúa la crecida máxima probable susceptible de ocurrir en la cuenca en estudio.
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Fosdick, Julie C., R. A. VanderLeest, J. E. Bostelmann, J. S. Leonard, R. Ugalde, J. L. Oyarzún, and Miguel Griffin. "Revised Timing of Cenozoic Atlantic Incursions and Changing Hinterland Sediment Sources during Southern Patagonian Orogenesis." Lithosphere 2020, no. 1 (September 4, 2020): 1–18. http://dx.doi.org/10.2113/2020/8883099.
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Abstract New detrital zircon U-Pb geochronology data from the Cenozoic Magallanes-Austral Basin in Argentina and Chile ~51° S establish a revised chronostratigraphy of Paleocene-Miocene foreland synorogenic strata and document the rise and subsequent isolation of hinterland sources in the Patagonian Andes from the continental margin. The upsection loss of zircons derived from the hinterland Paleozoic and Late Jurassic sources between ca. 60 and 44 Ma documents a major shift in sediment routing due to Paleogene orogenesis in the greater Patagonian-Fuegian Andes. Changes in the proportion of grains from hinterland thrust sheets, comprised of Jurassic volcanics and Paleozoic metasedimentary rocks, provide a trackable signal of long-term shifts in orogenic drainage divide and topographic isolation due to widening of the retroarc fold-thrust belt. The youngest detrital zircon U-Pb ages confirm timing of Maastrichtian-Eocene strata but require substantial age revisions for part of the overlying Cenozoic basinfill during the late Eocene and Oligocene. The upper Río Turbio Formation, previously mapped as middle to late Eocene in the published literature, records a newly recognized latest Eocene-Oligocene (37-27 Ma) marine incursion along the basin margin. We suggest that these deposits could be genetically linked to the distally placed units along the Atlantic coast, including the El Huemul Formation and the younger San Julián Formation, via an eastward deepening within the foreland basin system that culminated in a basin-wide Oligocene marine incursion in the Southern Andes. The overlying Río Guillermo Formation records onset of tectonically generated coarse-grained detritus ca. 24.3 Ma and a transition to the first fully nonmarine conditions on the proximal Patagonian platform since Late Cretaceous time, perhaps signaling a Cordilleran-scale upper plate response to increased plate convergence and tectonic plate reorganization.
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Luebert, Federico, and Patricio Pliscoff. "Variabilidad climática y bioclimas de la Región de Valparaíso, Chile." Investigaciones Geográficas, no. 44 (January 1, 2012): 41. http://dx.doi.org/10.5354/0719-5370.2012.26408.
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La Región de Valparaíso en su área continental se encuentra bajo la influencia de un clima mediterráneo.El análisis de datos de estaciones meteorológicas y de superficies climáticas, sugiere que la altitud yla posición topográfica respecto a la Cordillera de los Andes y de la Costa determinan la variacióndel clima al interior de la región. Proyecciones de cambio climático en el área continental de laRegión indican, en general, una tendencia al aumento de las temperaturas y a una disminución delas precipitaciones. Basándose en análisis de conglomerados, cinco bioclimas pueden reconocersedentro del área continental de la Región de Valparaíso: bioclima costero, bioclima interior, bioclima deserranías interiores, bioclima pre-andino y bioclima andino. El área insular del Archipiélago de JuanFernández también se encuentra bajo la influencia de clima mediterráneo, aunque bajo condicionesmás húmedas que el área continental. La Isla de Pascua presenta un bioclima tropical. Cada bioclimaes brevemente descrito de acuerdo a su ubicación y características climáticas y vegetacionales.
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Pérez, Alberto Enrique. "La mirada de Ngenechen. Representaciones anfibiomorfas aplicadas al pastillaje en la alfarería de la Patagonia Noroccidental Argentina." Comechingonia. Revista de Arqueología 13, no. 1 (September 1, 2010): 9–20. http://dx.doi.org/10.37603/2250.7728.v13.n1.17882.
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Nuevos hallazgos de alfarería prehispánica en la localidad de San Martín de los Andes, departamento Lácar, provincia de Neuquén, muestran la presencia de atributos decorativos zoomorfos abstractos o anfibiomorfos (ranas) estilizados en proximidad de ambientes fluviales. Estos atributos modelados fueron caracterizados históricamente como “mamelones”, en referencia a atributos sexuales femeninos y símbolos de fertilidad. Sin embargo, este tipo de decoración modelada, muy bien conocida en el territorio Centro Sur de Chile en la alfarería pre y post hispánica, se presenta como la gradual abstracción de representaciones anfibiomorfas hasta culminar preservando sus rasgos más distintivos, sus ojos, caracterizados técnicamente como protúberos. La representación del anfibio, además de un atributo estilístico, es postulada como evidencia de elementos de la cosmovisión compartidos por las poblaciones cazadoras-recolectoras complejas que ocupaban ambas vertientes de la Cordillera de los Andes entre los siglos III y XVIII de nuestra era.
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Lamb, Simon. "Cenozoic uplift of the Central Andes in northern Chile and Bolivia—reconciling paleoaltimetry with the geological evolution." Canadian Journal of Earth Sciences 53, no. 11 (November 2016): 1227–45. http://dx.doi.org/10.1139/cjes-2015-0071.
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The Cenozoic geological evolution of the Central Andes, along two transects between ∼17.5°S and 21°S, is compared with paleo-topography, determined from published paleo-altimetry studies. Surface and rock uplift are quantified using simple 2-D models of crustal shortening and thickening, together with estimates of sedimentation, erosion, and magmatic addition. Prior to ∼25 Ma, during a phase of amagmatic flat-slab subduction, thick-skinned crustal shortening and thickening (nominal age of initiation ∼40 Ma) was focused in the Eastern and Western Cordilleras, separated by a broad basin up to 300 km wide and close to sea level, which today comprises the high Altiplano. Surface topography at this time in the Altiplano and the western margin of the Eastern Cordillera appears to be ∼1 km lower than anticipated from crustal thickening, which may be due to the pull-down effect of the subducted slab, coupled to the overlying lithosphere by a cold mantle wedge. Oligocene steepening of the subducted slab is indicated by the initiation of the volcanic arc at ∼27–25 Ma, and widespread mafic volcanism in the Altiplano between 25 and 20 Ma. This may have resulted in detachment of mantle lithosphere and possibly dense lower crust, triggering 1–1.5 km of rapid uplift (over ≪5 Myrs) of the Altiplano and western margin of the Eastern Cordillera and establishing the present day lithospheric structure beneath the high Andes. Since ∼25 Ma, surface uplift has been the direct result of crustal shortening and thickening, locally modified by the effects of erosion, sedimentation, and magmatic addition from the mantle. The rate of crustal shortening and thickening varies with location and time, with two episodes of rapid shortening in the Altiplano, lasting <5 Myrs, that are superimposed on a long-term history of ductile shortening in the lower crust, driven by underthrusting of the Brazilian Shield on the eastern margin.
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CRUZ, JUAN LUIS OSSA SANTA. "The Army of the Andes: Chilean and Rioplatense Politics in an Age of Military Organisation, 1814–1817." Journal of Latin American Studies 46, no. 1 (February 2014): 29–58. http://dx.doi.org/10.1017/s0022216x13001570.
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AbstractThis article analyses the organisation of the Army of the Andes, created in Mendoza between 1814 and 1817 with the aim of reconquering Chile from the royalists. The first section studies the role of José de San Martín as an informal arbiter in Bernardo O'Higgins’ dispute with José Miguel Carrera. The aim is to explain why San Martín decided to support O'Higgins, and the immediate consequences of this alliance. The second section addresses the main characteristics of the Army of the Andes and the process of militarisation experienced by the local inhabitants. Everyday life in Mendoza became inseparable from the needs of the revolutionary army. The paper then considers the so-called guerra de zapa and the participation of irregular agents. The involvement of spies and guerrilla officers in the revolution increased as warfare intensified. The final section analyses the crossing of the cordillera by the insurgents and the revolutionary triumph of 12 February 1817 at Chacabuco.
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Alloatti, Norma. "Mis impresiones y mis vicisitudes en mi viaje a Europa pasando por el Estrecho de Magallanes y en mi excursión a Buenos Aires pasando por la cordillera de Los Andes." La Manzana de la Discordia 9, no. 2 (April 1, 2016): 115. http://dx.doi.org/10.25100/lamanzanadeladiscordia.v9i2.1609.
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De la Barra, Maipina (2013)Mis impresiones y mis vicisitudes en mi viaje a Europa pasando por el Estrecho de Magallanes y en mi excursión a Buenos Aires pasando por la cordillera de Los AndesReedición crítica del original publicado en 1878 a cargo de Carla Ulloa Inostroza (Transcripción, actualización ortográfica y estudio preliminar).Santiago, Chile, Editorial Cuarto Propio, diciembre 2013, 224 páginas,ISBN. 978-956-260-663-9.
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Chandia-Jaure, Rosa. "Los espacios hidráulicos en un paisaje andino. Un modelo técnico de adaptación local." Bitácora Urbano Territorial 27, no. 3 (September 1, 2017): 51–60. http://dx.doi.org/10.15446/bitacora.v27n3.53651.
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La investigación estudia el conjunto de conocimientos técnicos locales asociados a las trazas de agua existentes en un asentamiento de la cordillera de Los Andes representativo del paisaje cultural andino. A través del análisis de Socoroma, en el norte de Chile, se exponen las estrategias tecnológicas locales para el uso equilibrado del caudal del agua disponible, frente a eventos de escasez o excesos del recurso, mientras sirven de soporte a un sistema social y cultural que da forma a un habitar íntimamente vinculado al entorno. El análisis de estos espacios hidráulicos permite comprender las manifestaciones locales para organizar, construir y habitar un territorio en función de la adaptación al medio ambiente, así como su transformación en modelos de intervención futura, aplicables tanto en ámbitos rurales como urbanos.
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Margirier, A., L. Audin, J. Carcaillet, S. Schwartz, and C. Benavente. "Tectonic and climatic controls on the Chuquibamba landslide (western Andes, southern Peru)." Earth Surface Dynamics 3, no. 2 (June 25, 2015): 281–89. http://dx.doi.org/10.5194/esurf-3-281-2015.
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Abstract. The contribution of landslides to the Quaternary evolution of relief is poorly documented in arid contexts. In southern Peru and northern Chile, several massive landslides disrupt the arid western Andean front. The Chuquibamba landslide, located in southern Peru, belongs to this set of large landslides. In this area, the Incapuquio fault system captures the intermittent drainage network and localizes rotational landslides. Seismic activity is significant in this region with recurrent Mw 9 subduction earthquakes; however, none of the latest seismic events have triggered a major landslide. New terrestrial cosmogenic dating of the Chuquibamba landslide provides evidence that the last major gravitational mobilization of these rotational landslide deposits occurred at ~ 102 ka, during the Ouki wet climatic event identified on the Altiplano between 120 and 98 ka. Our results suggest that wet events in the arid and fractured context of the Andean forearc induced these giant debris flows. Finally, our study highlights the role of tectonics and climate on (i) the localization of large Andean landslides in the Western Cordillera and on (ii) the long-term mass transfer to the trench along the arid Andean front.
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Obregón Iturra, Jimena. "“Indios en collera”, deportaciones coloniales de trabajadores Huarpes y Aucaes. Razón de Estado e intereses particulares. Chile, 1598-1658." Tiempo Histórico, no. 16 (July 16, 2019): 15–38. http://dx.doi.org/10.25074/th.v0i16.1207.
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El análisis caracteriza los desplazamientos bajo apremio a los que fueron sometidos, en la primera mitad del siglo XVII, miembros de dos pueblos originarios que se encontraban en situaciones distintas ante el poder colonial español. Los huarpes eran indios de encomienda, deportados en colleras por vía terrestre desde Cuyo hacia Santiago, a través de la cordillera de los Andes. Por su parte, los araucano-mapuches llamados aucaes, eran esclavos de guerra que, también atados en colleras, fueron transportados en navíos hacia Lima/El Callao. El artículo indaga las condiciones materiales de los traslados indígenas, así como el tipo de deportación al que se procedió. Las élites coloniales necesitadas de mano de obra, buscaban más bien acercar a los deportados a los centros de poder y regiones aledañas, logrando a menudo que las autoridades hispanas hicieran caso omiso de la vertiente protectora de la legislación de Indias.
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Iroumé, Andrés, and Maritza Schäfer. "VARIABILIDAD ESPACIAL Y TEMPORAL DE LA INFILTRACIÓN EN UNA CUENCA EXPERIMENTAL EN LA CORDILLERA DE LOS ANDES, IX REGIÓN, CHILE." Agro Sur 28, no. 2 (July 2000): 1–9. http://dx.doi.org/10.4206/agrosur.2000.v28n2-01.
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Breitkreuz, Christoph, Shanaka L. de Silva, Hans G. Wilke, Jörg A. Pfänder, and Axel D. Renno. "Neogene to Quaternary ash deposits in the Coastal Cordillera in northern Chile: Distal ashes from supereruptions in the Central Andes." Journal of Volcanology and Geothermal Research 269 (January 2014): 68–82. http://dx.doi.org/10.1016/j.jvolgeores.2013.11.001.
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Melnick, Daniel, François Charlet, Helmut P. Echtler, and Marc De Batist. "Incipient axial collapse of the Main Cordillera and strain partitioning gradient between the central and Patagonian Andes, Lago Laja, Chile." Tectonics 25, no. 5 (October 2006): n/a. http://dx.doi.org/10.1029/2005tc001918.
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Sanhueza Díaz, Lilian, Marisol Chávez Herting, María Teresa Douzet Carafi, and Milton Smythe Bendel. "Araucanía – Comahue: un espacio transnacional de migración en Chile y Argentina." REVISTA CUHSO 29, no. 1 (July 29, 2019): 59–79. http://dx.doi.org/10.7770/cuhso.v29i1.1898.
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Este artículo expone las características de la migración transfronteriza en el territorio Araucanía–Comahue, ubicado en la frontera sur de Chile y Argentina. Hoy en día es conocido como corredor, denominación dada en el marco de políticas de desarrollo impulsadas por los Estados-nación a espacios marginales anexados tardíamente al territorio nacional. Pero cabe destacar que ya en el siglo XVII, este espacio comunicaba y vinculaba a los habitantes del Wallmapu de cada lado de la cordillera de los Andes. Así, el objetivo es describir la movilidad humana indígena documentada por la historiografía y las dinámicas y prácticas transnacionales que se rescatan de las experiencias relatadas por chilenos y argentinos que migraron en esta zona desde mediados de siglo XX y que han utilizado las mismas rutas de los pueblos originarios. La información recabada muestra que esta migración transfronteriza es un fenómeno histórico y vigente que hoy impone desafíos al Estado. Por ello, se propone la noción de corredor humano Araucanía–Comahue que critica y complementa la actual idea de corredor. Si bien ésta reconoce el intercambio histórico, se focaliza en el desarrollo económico y el intercambio de bienes, sin atender a las características de la movilidad humana, las razones históricas de su circulación, las motivaciones actuales y, por ende, las condiciones necesarias para favorecer la calidad de vida de quienes transitan a través del macizo cordillerano.
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Bandierie, Susana O. "La Cordillera de los Andes en el norte de Patagonia o la frontera argentino-chilena como espacio social. Un estudio de caso." Estudios Fronterizos, no. 22 (May 1, 1990): 81–108. http://dx.doi.org/10.21670/ref.1990.22.a04.
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En este trabajo se muestra la permanencia de las relaciones socioeconómicas y culturales en la región fronteriza del Neuquén, que se ubica entre Chile y Argentina; en donde la imposición de límites jurídico-administrativos no afectó su funcionamiento ni la expresión territorial de la ganadería extensiva como actividad dominante. La descomposición de esta región se presentó a partir de 1930, con la fijación de una frontera comercial que provocó una crisis generalizada en la actividad ganadera. Esto trajo como consecuencia el incremento de su marginalidad socioeconómica y un proceso de despoblamiento de la región.
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Blanco, Graciela. "Las sociedades anónimas cruzan los Andes: los inversores chilenos en Neuquén al comenzar el siglo XX." América Latina en la Historia Económica 19, no. 2 (May 1, 2012): 107. http://dx.doi.org/10.18232/alhe.v19i2.519.
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<p><span style="font-family: Times New Roman; font-size: small;"> </span><span style="font-size: small;"><span style="font-family: Times New Roman;">El territorio de Neuquén, en el norte de la Patagonia, atrajo la mirada de diversos inversores privados a partir del avance militar que realizó el Estado nacional sobre los grupos indígenas y de la conquista de las tierras del sur argentino; tierras que fueron ofrecidas a particulares en propiedad o arrendamiento en condiciones muy beneficiosas. Este trabajo analiza la conformación en Chile, en los primeros años del siglo <span style="text-transform: uppercase;">xx</span>, de sociedades anónimas que explicitaban como objetivo central la intención de comprar tierras a ambos lados de la Cordillera de los Andes para la explotación agroganadera y la comercialización, y estudia específicamente el origen, itinerario y organización productiva de una de esas sociedades en Neuquén.</span></span></p><p><span style="font-family: Times New Roman; font-size: small;"> </span></p>
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Maza, S. N., G. Collo, D. Morata, C. Lizana, E. Camus, M. Taussi, A. Renzulli, et al. "Clay mineral associations in the clay cap from the Cerro Pabellón blind geothermal system, Andean Cordillera, Northern Chile." Clay Minerals 53, no. 2 (June 2018): 117–41. http://dx.doi.org/10.1180/clm.2018.9.
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ABSTRACTThe occurrence of smectite-illite and smectite-chlorite minerals series was studied along a thick clay cap (~300 m) drilled in the Cerro Pabellón geothermal field (northern Andes, Chile). X-ray diffraction (XRD) and scanning electronic microscopy (SEM) were used to characterize the alteration mineralogy and clay mineral assemblages and their changes with depth. Cerro Pabellón is a high-enthalpy blind geothermal system, with a reservoir zone from ~500 m to 2000 m depth, with temperatures of 200–250°C. Three main hydrothermal alteration zones were identified: (1) argillic; (2) sub-propylitic, and (3) propylitic, with variable amounts of smectite, illite-smectite, chlorite-smectite, mixed-layer chlorite-corrensite, illite and chlorite appearing in the groundmass and filling amygdales and veinlets. Chemical and XRD data of smectites, I-S and illites show, with some exceptions, a progressive illitization with depth. The evolution of I-S with depth, shows a sigmoidal variation in the percentage of illite layers, with the conversion of smectite to R1 I-S at ~180–185°C. These temperatures are greater than those reported for other similar geothermal fields and might indicate, at least in part, the efficiency of the clay cap in terms of restricting the circulation of hydrothermal fluids in low-permeability rocks. Our results highlight the importance of a better understanding of clay-mineral evolution in active geothermal systems, not only as a direct (or indirect) way to control temperature evolution, but also as a control on permeability/porosity efficiency of the clay cap.
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Calderón Sánchez, Sergio. "Respuesta del Eucalyptus globulus ssp. globulus a fertilizaciones de apoyo en la VIII Región." Ciencia & Investigación Forestal 5, no. 1 (July 6, 1991): 5–21. http://dx.doi.org/10.52904/0718-4646.1991.144.
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En las zonas húmedas templadas costeras de la provincia de Concepción y húmedas de la Cordillera de Los Andes en la provincia de Bio-Bio, Chile, se probaron diversas combinaciones de fertilizantes, aplicadas en dosis subdivididas dentro de los tres primeros años de edad en plantaciones de Eucalyptus globulus ssp. globulus. Los resultados indican que en el ensayo de la zona costera de la provincia de Concepción las aplicaciones de urea producen la mejor respuesta, tanto en términos de producción física como económica, mostrando una rentabilidad superior al 12% En el ensayo de la zona precordillerana andina en tanto, la mejor respuesta la ofrece una combinación de N, P, K y B, registrando una alta supervivencia y el mayor rendimiento volumétrico. Este tratamiento arroja también una rentabilidad superior al 12% Los ensayos confirman que las fertilizaciones de apoyo en serie durante la época juvenil, en plantaciones establecidas en suelos con deficiencias nutricionales, inducen un crecimiento adicional de importancia si la abertura del dosel es suficiente.
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Vargas Easton, Gabriel, Jorge Inzulza Contardo, Sonia Pérez Tello, Daniela Ejsmentewicz Cáceres, and Catalina Jiménez Yáñez. "¿Urbanización fallada? La Falla San Ramón como nuevo escenario de riesgo sísmico y la sostenibilidad de Santiago, Chile." Revista de Urbanismo, no. 38 (June 30, 2018): 1. http://dx.doi.org/10.5354/0717-5051.2018.48216.
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Santiago de Chile, habitada por cerca de 7 millones de personas, se ubica a los pies del flanco occidental de la Cordillera Principal de Los Andes, uno de los cordones montañosos más activos de nuestro planeta. La zona oriente de Santiago ha experimentado una expansión urbana sin precedentes en las últimas cuatro décadas, generando un aumento de la exposición de sus habitantes a riesgos socio-naturales de origen geológico, entre ellos la posibilidad de terremotos corticales asociados a la Falla San Ramón. El presente trabajo explora este nuevo escenario de amenaza sísmica, utilizando cartografía especializada a partir de cinco estados de avance claves para la ciudad, impulsados por políticas urbanas nacionales e instrumentos de planificación intercomunal desde 1960 hasta la actualidad. Los resultados muestran que esta urbanización acelerada ha alcanzado un 55% de la traza en superficie de la falla, lo cual no ha sido considerado en las regulaciones. Se concluye en la necesidad de avanzar en los vacíos normativos a través de la articulación de la amenaza sísmica natural con el medio urbano, como base para la reducción del riesgo de desastres y un desarrollo sostenible que considere además las inequidades de la urbe.
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Richter, M. "To what extent do natural disturbances contribute to Andean plant diversity? A theoretical outline from the wettest and driest parts of the tropical Andes." Advances in Geosciences 22 (October 13, 2009): 95–105. http://dx.doi.org/10.5194/adgeo-22-95-2009.
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Abstract. This paper deals with natural disturbances and their impact on vascular plant enrichment at two climatically contrasting Andean ranges, i.e. the perhumid Cordillera Real in southern Ecuador and the arid Cordillera de Atacama in northern Chile. In the first case, main triggers for an additional input of pioneer species during succession stages initiated by perturbations are landslides, mudflows, and, to a lesser extent, cohort mortality, floods, and wildlife damages. Droughts and wind are stressors, which reduce plant growth but hardly plant diversity, in contrast to enhanced UV radiation with its mutagen effect. Though stress effects are similar in the Atacama, disturbance regimes differ considerably in this dry mountain environment. Here, most perturbations are of small dimension such as nitrogen inputs by feces of Lamoids and burrow activities of tuco-tuco mice, both of them fostering nitrophilous plant communities. Flooding, gelifluction, and other denudation processes such as sheet wash occur too, however, do not charge species enrichment in the dry Andes. Although the perhumid study site represents one of the world's plant diversity "hotspots" and, by contrast, the arid one a comparatively "coldspot", pioneer species during successive stages after natural disturbances contribute in a similar percentage to the total plant inventories (appr. 10% of the species numbers). Relatively seen, natural disturbances are most important for species enrichment in the Atacama (200–500 species per 10 000 km2), while most other ecological factors delimit plant survival. Instead, plant life at the Ecuadorian study area benefits from many climatic and edaphic site conditions, and consequently, disturbances are considered only one of many driving forces for its hotspot status (>5000 species per 10 000 km2).
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Masiokas, Mariano H., Ricardo Villalba, Brian H. Luckman, Carlos Le Quesne, and Juan Carlos Aravena. "Snowpack Variations in the Central Andes of Argentina and Chile, 1951–2005: Large-Scale Atmospheric Influences and Implications for Water Resources in the Region." Journal of Climate 19, no. 24 (December 15, 2006): 6334–52. http://dx.doi.org/10.1175/jcli3969.1.
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Abstract The snowpack in the central Andes (30°–37°S) is the primary source for streamflow in central Chile and central-western Argentina, but few published studies are available on snowpack variability in the region. This paper develops the first regional snowpack series (1951–2005) from Chilean and Argentinean snow course records. This series shows a strong regional signal, marked interannual variability, and a positive, though nonsignificant, linear trend. Correlations with local precipitation and temperature records reveal a marked association with conditions in central Chile. High snow accumulation is generally concurrent with El Niño events in the tropical Pacific, but only 5 of the 10 driest years coincided with La Niña events. Evaluation of 500-hPa geopotential height anomaly maps during extreme snow years highlights the crucial significance of tropospheric conditions in the subtropical and southeast Pacific in modulating snowfall. Correlations with gridded SST and SLP data and multiple regressions with large-scale climatic indices corroborate a Pacific ENSO-related influence largely concentrated during the austral winter months. This hampers the predictability of snowpack before the onset of the cold season. Annual and warm-season river discharges on both sides of the cordillera are significantly correlated with the regional snowpack record and show positive linear trends over the 1951–2004 common period, probably related to a greater frequency of above-average snowpacks during recent decades. Future demand and competition for water resources in these highly populated regions will require detailed information about temporal and spatial variations in snow accumulation over the Andes. The results indicate that the relationships between snowpack and atmospheric circulation patterns prior to the winter season are complex, and more detailed analyses are necessary to improve prediction of winter snowfall totals.
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Ferrando, Francisco. "Sobre la distribución de Glaciares Rocosos en Chile, análisis de la situación y reconocimiento de nuevas localizaciones." Investigaciones Geográficas, no. 54 (December 29, 2017): 127. http://dx.doi.org/10.5354/0719-5370.2017.48045.
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La existencia de glaciares rocosos en diversas regiones de Chile ha sido indistintamente reconocida por algunos inventarios y no considerada por otros. Estudios particulares han revelado desde mediados del siglo XX su presencia en diferentes lugares del país. Pero, tanto estos como los inventarios distan aun
de expresar la real extensión areal de su distribución así como de sus características o del volumen de recurso hídrico que representan. Por tanto, el objetivo de esta contribución es aportar al conocimiento de la real distribución de los glaciares rocosos en Chile. Con este fin se revisan antecedentes sobre la
existencia de glaciares rocosos en la Cordillera de los Andes de Chile, sobre el conocimiento actual de su distribución zonal y regional, y se ratifica la presencia de ellos en unos casos, y su evolución en otros desde que fueron descritos y cartografiados por primera vez. Finalmente, mediante imágenes satelitales
se reconocen glaciares rocosos no identificados previamente en las regiones de Atacama, Maule, Aysén y Magallanes, lo que se suma a otros recientemente informados en la región de Valparaíso. De entre ellos, resaltan los glaciares rocosos descubiertos en el Parque Nacional Torres del Paine, entre los 50°56’
y 50°58’ de latitud S, constituyendo evidencia de los efectos del cambio climático, especialmente de la tendencia térmica regional.
Como resultado, se establece la presencia de glaciares rocosos con diferentes tipologías y estados evolutivos, en sectores andinos y volcánicos a latitudes menores y mayores que las indicadas en estudios previos, lo que viene a aportar al conocimiento sobre estas expresiones de permafrost en Chile y al inventario nacional de glaciares.
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Cornwell, E., N. P. Molotch, and J. McPhee. "Spatio-temporal variability of snow water equivalent in the extra-tropical Andes Cordillera from distributed energy balance modeling and remotely sensed snow cover." Hydrology and Earth System Sciences 20, no. 1 (January 25, 2016): 411–30. http://dx.doi.org/10.5194/hess-20-411-2016.
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Abstract. Seasonal snow cover is the primary water source for human use and ecosystems along the extratropical Andes Cordillera. Despite its importance, relatively little research has been devoted to understanding the properties, distribution and variability of this natural resource. This research provides high-resolution (500 m), daily distributed estimates of end-of-winter and spring snow water equivalent over a 152 000 km2 domain that includes the mountainous reaches of central Chile and Argentina. Remotely sensed fractional snow-covered area and other relevant forcings are combined with extrapolated data from meteorological stations and a simplified physically based energy balance model in order to obtain melt-season melt fluxes that are then aggregated to estimate the end-of-winter (or peak) snow water equivalent (SWE). Peak SWE estimates show an overall coefficient of determination R2 of 0.68 and RMSE of 274 mm compared to observations at 12 automatic snow water equivalent sensors distributed across the model domain, with R2 values between 0.32 and 0.88. Regional estimates of peak SWE accumulation show differential patterns strongly modulated by elevation, latitude and position relative to the continental divide. The spatial distribution of peak SWE shows that the 4000–5000 m a.s.l. elevation band is significant for snow accumulation, despite having a smaller surface area than the 3000–4000 m a.s.l. band. On average, maximum snow accumulation is observed in early September in the western Andes, and in early October on the eastern side of the continental divide. The results presented here have the potential of informing applications such as seasonal forecast model assessment and improvement, regional climate model validation, as well as evaluation of observational networks and water resource infrastructure development.
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Lapere, Rémy, Sylvain Mailler, and Laurent Menut. "The 2017 Mega-Fires in Central Chile: Impacts on Regional Atmospheric Composition and Meteorology Assessed from Satellite Data and Chemistry-Transport Modeling." Atmosphere 12, no. 3 (March 6, 2021): 344. http://dx.doi.org/10.3390/atmos12030344.
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In January 2017, historic forest fires occurred in south-central Chile. Although their causes and consequences on health and ecosystems were studied, little is known about their atmospheric effects. Based on chemistry-transport modeling with WRF-CHIMERE, the impact of the 2017 Chilean mega-fires on regional atmospheric composition, and the associated meteorological feedback, are investigated. Fire emissions are found to increase pollutants surface concentration in the capital city, Santiago, by +150% (+30 µg/m3) for PM2.5 and +50% (+200 ppb) for CO on average during the event. Satellite observations show an intense plume extending over 2000 km, well reproduced by the simulations, with Aerosol Optical Depth at 550 nm as high as 4 on average during the days of fire activity, as well as dense columns of CO and O3. In addition to affecting atmospheric composition, meteorology is also modified through aerosol direct and indirect effects, with a decrease in surface radiation by up to 100 W/m2 on average, leading to reductions in surface temperatures by 1 K and mixing layer heights over land by 100 m, and a significant increase in cloud optical depth along the plume. Large deposition fluxes of pollutants over land, the Pacific ocean and the Andes cordillera are found, signaling potential damages to remote ecosystems.
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Martínez, F., A. Maksymowicz, H. Ochoa, and D. Díaz. "Geometry of the inverted Cretaceous Chañarcillo Basin based on 2-D gravity and field data. An approach to the structure of the western Central Andes of northern Chile." Solid Earth Discussions 7, no. 3 (August 17, 2015): 2311–46. http://dx.doi.org/10.5194/sed-7-2311-2015.
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Abstract. This paper discusses an integrated approach that provides new ideas about the structural geometry of the NNE-striking, Cretaceous Chañarcillo Basin located along the eastern Coastal Cordillera in the western Central Andes of northern Chile (27–28° S). The results obtained from the integration of two transverse (E–W) gravity profiles with previous geological information, show that the architecture of this basin is defined by a large NNE–SSE-trending and east-vergent anticline ("Tierra Amarilla Anticlinorium"), which is related to the positive reactivation of a former Cretaceous normal fault (Elisa de Bordos Master Fault). Moreover, intercalations of high and low gravity anomalies and steep gravity gradients reveal a set of buried, west-tilted half-grabens associated with a synthetic normal fault pattern. These results, together with the uplift and folding style of the Cretaceous syn-rift recognized within the basin, suggest that their complete structural geometry could be explained by an inverted fault system linked to the shortening of pre-existing Cretaceous normal fault systems. Ages of the synorogenic deposits exposed unconformably over the frontal limb of the Tierra Amarilla Anticlinorium confirm a Late Cretaceous age for the Andean deformation and tectonic inversion of the basin.
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Cornwell, E., N. P. Molotch, and J. McPhee. "Spatio-temporal variability of snow water equivalent in the extra-tropical Andes cordillera from a distributed energy balance modeling and remotely sensed snow cover." Hydrology and Earth System Sciences Discussions 12, no. 9 (September 3, 2015): 8927–76. http://dx.doi.org/10.5194/hessd-12-8927-2015.
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Abstract. Seasonal snow cover is the primary water resource precursor for human use and environmental sustain along the extratropical Andes Cordillera. Despite its importance, relatively little research has been devoted to understanding the properties, distribution and variability of this natural resource. This research provides high-resolution distributed estimates of end-of-winter and spring snow water equivalent over a 152 000 km2 domain that includes the mountainous reaches of central Chile and Argentina. Remotely sensed fractional snow covered area and other relevant forcings are combined with extrapolated data from meteorological stations and a simplified physically-based energy balance model in order to obtain melt-season peak SWE. Estimates show an overall coefficient of determination R2 of 0.61 compared to observations at 12 automatic snow water equivalent sensors distributed across the model domain, with R2 values between 0.32 and 0.88. Regional estimates of peak SWE accumulation show differential patterns strongly modulated by elevation, latitude and position relative to the continental divide. Average peak SWE increases by nearly 500 mm for every 1000 m in elevation gain for the central and southern sub-regions of the model domain, but this effect is much less pronounced in the northern reaches. The 3000–4000 m a.s.l. elevation band is the most significant accumulation area for most of the northern and central reaches of the domain, although the 4000–5000 m a.s.l. band, despite a smaller contributing area, almost doubles the accumulation amounts estimated for the lower adjacent subdomain. Snow accumulation reaches an earlier peak in the western Andes, and the eastern side of the continental divide shows lower snow accumulation at all elevations except for the southern region represented by the Neuquén River Basin. The results presented here have the potential of informing applications such as seasonal forecast model assessment and improvement, regional climate model validation, as well as evaluation of observational networks and water resource infrastructure development.
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Lapere, Rémy, Laurent Menut, Sylvain Mailler, and Nicolás Huneeus. "Seasonal variation in atmospheric pollutants transport in central Chile: dynamics and consequences." Atmospheric Chemistry and Physics 21, no. 8 (April 28, 2021): 6431–54. http://dx.doi.org/10.5194/acp-21-6431-2021.
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Abstract. Central Chile faces atmospheric pollution issues all year long as a result of elevated concentrations of fine particulate matter during the cold months and tropospheric ozone during the warm season. In addition to public health issues, environmental problems regarding vegetation growth and water supply, as well as meteorological feedback, are at stake. Sharp spatial gradients in regional emissions, along with a complex geographical situation, make for variable and heterogeneous dynamics in the localization and long-range transport of pollutants, with seasonal differences. Based on chemistry–transport modeling with Weather Research Forecasting (WRF)–CHIMERE, this work studies the following for one winter period and one summer period: (i) the contribution of emissions from the city of Santiago to air pollution in central Chile, and (ii) the reciprocal contribution of regional pollutants transported into the Santiago basin. The underlying 3-dimensional advection patterns are investigated. We find that, on average for the winter period, 5 to 10 µg m−3 of fine particulate matter in Santiago come from regional transport, corresponding to between 13 % and 15 % of average concentrations. In turn, emissions from Santiago contribute between 5 % and 10 % of fine particulate matter pollution as far as 500 km to the north and 500 km to the south. Wintertime transport occurs mostly close to the surface. In summertime, exported precursors from Santiago, in combination with mountain–valley circulation dynamics, are found to account for most of the ozone formation in the adjacent Andes cordillera and to create a persistent plume of ozone of more than 50 ppb (parts per billion), extending along 80 km horizontally and 1.5 km vertically, and located slightly north of Santiago, several hundred meters above the ground. This work constitutes the first description of the mechanism underlying the latter phenomenon. Emissions of precursors from the capital city also affect daily maxima of surface ozone hundreds of kilometers away. In parallel, cutting emissions of precursors in the Santiago basin results in an increase in surface ozone mixing ratios in its western area.
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Rubilar, Juan, Fernando Martínez, César Arriagada, Juan Becerra, and Sebastián Bascuñán. "Structure of the Cordillera de la Sal: A key tectonic element for the Oligocene-Neogene evolution of the Salar de Atacama basin, Central Andes, northern Chile." Journal of South American Earth Sciences 87 (November 2018): 200–210. http://dx.doi.org/10.1016/j.jsames.2017.11.013.
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Rojas, Maisa. "Multiply Nested Regional Climate Simulation for Southern South America: Sensitivity to Model Resolution." Monthly Weather Review 134, no. 8 (August 1, 2006): 2208–23. http://dx.doi.org/10.1175/mwr3167.1.
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Abstract Results are reported from two 5-month-long simulations for southern South America using the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5). The periods of simulation correspond to May–September 1997 and 1998, which were anomalously wet and dry winters for central Chile, respectively. The model setup includes triply nested, two-way-interacting domains centered over the eastern South Pacific and the western coast of southern South America, with horizontal grid intervals of 135, 45, and 15 km. Boundary conditions are provided from NCEP–NCAR reanalyzed fields. The analysis focuses on two subregions of central Chile (30°–41°S). Region 1 (32°–35°S), which is where the observed interannual precipitation differences are largest, is topographically very complex, with a mean height of the Andes Cordillera around 4500 m. Region 2 (35°–39°S) has relatively smooth terrain, as the mean height of the Andes drops to 3000 m. Station precipitation and temperature data are used for model validation. The model exhibits a negative temperature bias (from 2° to 5°C), as well as a positive precipitation bias (40%–80%). This precipitation bias can be partially explained by a positive moisture bias over the ocean in the model. In addition, these biases are highly correlated to the representation of terrain and station elevation in the model. The highest-resolution domain has the smallest precipitation bias for low-elevation stations, but a large positive bias at high altitudes (up to 300%). It also has a better representation of the spatial distribution of the precipitation, especially in region 1, where topography has a larger impact on the precipitation. Overall, the model domain with highest resolution best reproduces the observed precipitation and temperature, as well as the interannual differences. However, this study also shows that large improvements in the simulations of the surface variables are obtained when downscaling from 135 to 45 km, but much smaller improvements are found when downscaling from 45 to 15 km. These simulations represent the first effort in simulating seasonal precipitation in this topographically complex region of the Southern Hemisphere.
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Réveillet, Marion, Shelley MacDonell, Simon Gascoin, Christophe Kinnard, Stef Lhermitte, and Nicole Schaffer. "Impact of forcing on sublimation simulations for a high mountain catchment in the semiarid Andes." Cryosphere 14, no. 1 (January 17, 2020): 147–63. http://dx.doi.org/10.5194/tc-14-147-2020.
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Abstract. In the semiarid Andes of Chile, farmers and industry in the cordillera lowlands depend on water from snowmelt, as annual rainfall is insufficient to meet their needs. Despite the importance of snow cover for water resources in this region, understanding of snow depth distribution and snow mass balance is limited. Whilst the effect of wind on snow cover pattern distribution has been assessed, the relative importance of melt versus sublimation has only been studied at the point scale over one catchment. Analyzing relative ablation rates and evaluating uncertainties are critical for understanding snow depth sensitivity to variations in climate and simulating the evolution of the snowpack over a larger area and over time. Using a distributed snowpack model (SnowModel), this study aims to simulate melt and sublimation rates over the instrumented watershed of La Laguna (513 km2, 3150–5630 m a.s.l., 30∘ S, 70∘ W), during two hydrologically contrasting years (i.e., dry vs. wet). The model is calibrated and forced with meteorological data from nine Automatic Weather Stations (AWSs) located in the watershed and atmospheric simulation outputs from the Weather Research and Forecasting (WRF) model. Results of simulations indicate first a large uncertainty in sublimation-to-melt ratios depending on the forcing as the WRF data have a cold bias and overestimate precipitation in this region. These input differences cause a doubling of the sublimation-to-melt ratio using WRF forcing inputs compared to AWS. Therefore, the use of WRF model output in such environments must be carefully adjusted so as to reduce errors caused by inherent bias in the model data. For both input datasets, the simulations indicate a similar sublimation fraction for both study years, but ratios of sublimation to melt vary with elevation as melt rates decrease with elevation due to decreasing temperatures. Finally results indicate that snow persistence during the spring period decreases the ratio of sublimation due to higher melt rates.
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Krause-Sakate, R., A. S. Jadão, A. C. Firmino, M. A. Pavan, F. M. Zerbini, I. M. Rosales, P. Bustamante, and O. Le Gall. "First Report of a Lettuce-Infecting Sequivirus in Chile." Plant Disease 89, no. 10 (October 2005): 1129. http://dx.doi.org/10.1094/pd-89-1129a.
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Sequiviruses are isometric aphidborne plant viruses. Dandelion yellow mosaic virus (DaYMV), genus Sequivirus, was isolated from dandelion and lettuce in Europe. Lettuce mottle virus (LeMoV), a putative sequivirus, is often found in mixed infections with Lettuce mosaic virus (LMV) in Brazil (3). DaYMV, LeMoV and LMV cause similar mosaics in field-grown lettuce. Differences in biology and sequence suggest that DaYMV and LeMoV are distinct species (2). Forty-two and 101 lettuce samples with mosaic symptoms collected from two locations near Santiago during a survey of lettuce viruses in Chile in 2002 and 2003, respectively, were analyzed for the presence of LeMoV using reverse transcription polymerase chain reaction (RT-PCR). Total RNA was extracted (1) and used for RT-PCR with the specific LeMoV primers pairs Lmo3 (5′ ACATGAGCACTAGTGAGG 3′) and Lmo4 (5′ AGATAGAGCCGTCT GGCG 3′) (2). One of the 42 and three of the 101 samples produced the expected 300-bp fragment. Isometric particles of 30 nm diameter, typical of a sequivirus, were visualized by transmission electron microscopy. These samples were tested using RT-PCR for the presence of LMV and Cucumber mosaic virus (CMV), but no mixed infections were observed. One isolate, Ch36, was reamplified with the degenerate primer pairs DALE 1 (5′ GARTTCAACATGCACGCCAG 3′) and DALE 2 (5′ TTTTTCTCCCCATYCGTCAT 3′) which amplify part of the putative replicase gene (2) and produced a 563-bp fragment that was cloned on pGEM-T Easy (Promega, Madison, WI) and sequenced. The Ch36 product (EMBL Accession No. AM039965) showed 97% amino acid identity with LeMoV from Brazil, 79% with DaYMV, 72% with the sequivirus Parsnip yellow fleck virus, and 34% with the waikavirus Maize chlorotic dwarf virus. To our knowledge, this is the first report of a sequivirus in field lettuce in Chile, and although the virus was found at low incidence, this report extends the range of LeMoV to the western side of the Cordillera de Los Andes. The impact of LeMoV needs to be further analyzed in Chile, Brazil, and possibly other South American countries. References: (1) Y. D. Bertheau et al. DNA amplification by polymerase chain reaction (PCR) 1998. In: Methods for the Detection and Quantification of Erwinia carotovora subsp. atroseptica on potatoes. M. C. N. Perombelon and J. M. van der Wolff, eds. Scott. Crop Res. Inst. Occasional Publ., Dundee, 1998. (2) A. S. Jadão. Caracterização parcial e desenvolvimento de oligonucleotídeos específicos para detecção de sequivirus infectando alface. Ph.D. thesis. FCA-UNESP-Botucatu, Brazil, 2004. (3) O. Stangarlin et al. Plant Dis. 84:490, 2000.
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Giambiagi, Laura, Pamela Alvarez, and Silvana Spagnotto. "Temporal variation of the stress field during the construction of the central Andes: Constrains from the volcanic arc region (22-26°S), Western Cordillera, Chile, during the last 20 Ma." Tectonics 35, no. 9 (September 2016): 2014–33. http://dx.doi.org/10.1002/2016tc004201.
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Quispe, D. M., and K. Lavado. "Modelo bioeconómico de esquila única en el manejo de la fibra de vicuña." Archivos de Zootecnia 68, no. 263 (July 15, 2019): 348–55. http://dx.doi.org/10.21071/az.v68i263.4192.
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La vicuña (Vicugna vicugna) es un camélido sudamericano que se distribuye a lo largo de Cordillera de los Andes, con una mayor concentración de la población en el altiplano Perú - Bolivia, norte de Chile y Argentina. El objetivo de la investigación fue determinar los valores del máximo técnico (edad máxima de esquila), óptimo técnico (edad de mayor producción de fibra) y óptimo económico (periodicidad de esquila) para la esquila de la fibra de vicuña en función al modelo bioeconomico basado en la información del Centro Nacional de Conservación de Camélidos Sudamericanos sede Cala-Cala, en la provincia San Antonio de Putina, región Puno, Perú. El modelo bioeconómico corresponde a la esquila única a precio constante bajo cinco escenarios para tasas de descuento (niveles de rentabilidad) desde el 9% al 30%, en ello, se determinan los valores del máximo técnico, óptimo técnico y óptimo económico. Los resultados mostraron que el valor del máximo técnico para vicuñas hembras corresponde a 15.8 años, en tanto que para vicuñas machos alcanza 17.76 años, lo anterior evidencia que las vicuñas machos viven más que las vicuñas hembras, ello se explica a factores ambientales en el caso de las vicuñas hembras. Asimismo, se observa que, en un escenario donde la unidad productora de fibra de vicuña enfrenta diversos costos de oportunidad (niveles de rentabilidad), se observa que la presión sobre la especie será más exigente en la medida que la tasa de descuento sea más alta, variando la periodicidad de esquila óptima desde 2.6 a 1.25 años correspondiente a una tasa de descuento de 9% y 30%, respectivamente.
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Vidal-Russell, Romina, Cintia P. Souto, and Andrea C. Premoli. "Multiple Pleistocene refugia in the widespread Patagonian tree Embothrium coccineum (Proteaceae)." Australian Journal of Botany 59, no. 4 (2011): 299. http://dx.doi.org/10.1071/bt10303.
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Embothrium coccineum J.R.Forst. & G.Forst is an endemic tree of the Patagonian temperate forest. The objective of this study is to evaluate the impact of last glaciation events on the genetic structure of this widespread and ecologically tolerant species, to postulate possible refugial areas. Phylogeographic analyses were performed using chloroplast DNA sequences (trnL-trnF spacer and ndhC-trnV spacer) from individuals collected in 34 populations along the total range of the species, and these results were compared with a similar study in Nothofagus. A total of 22 haplotypes were found, three of which were widely distributed while 13 were found at only one location. Historical demography suggests a long period of stable effective population size, decreasing gradually towards the Last Glacial Maximum (LGM), followed by an increase in population size that stabilised 2500 years ago. The phylogeographic analyses reflect recent events of colonisation after the LGM from multiple refugia. In the northern area of its distribution probably the species survived in several pockets within the Andes mountain range and in Cordillera de la Costa in Chile. In the south, it is suggested that Embothrium survived the glacial period at the edge of the glaciers. These findings are in agreement with the fossil pollen record that shows 10 000-year-old grains in the south, suggesting colonisation from nearby areas when ice retreated. Embothrium is a coloniser that naturally occurs as scattered individuals within mixed forests. Hence, the shallow phylogeographic structure reported here reflects a Pleistocene signature highly impacted by drift resulting in the randomly fixation of new variants reducing the cpDNA structure.
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Olivero, Eduardo B., and Daniel R. Martinioni. "Late Albian inoceramid bivalves from the Andes of Tierra del Fuego: Age implications for the closure of the Cretaceous marginal basin." Journal of Paleontology 70, no. 2 (March 1996): 272–74. http://dx.doi.org/10.1017/s0022336000023349.
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At the southernmost tip of South America, a thick pile of deep marine volcaniclastic rocks called the Yahgan Formation (Kranck, 1932) was deposited during the Early Cretaceous in a small marginal basin developed between the continent and a Pacific-facing volcanic arc (Katz, 1972; Dalziel et al., 1974). North and northwest of Tierra del Fuego, in the adjacent Austral or Magallanes basin, this unit is laterally replaced by coeval, fine-grained deposits representing basinal, slope, and platform marine settings (Winslow, 1982; Biddle et al., 1986; Wilson, 1991). The geometry of the basins changed markedly with a compressional event that produced the tectonic inversion of the marginal basin and the formation of a retroarc foreland basin in front of the rising cordillera. Closure of the marginal basin and strong deformation of the Yahgan Formation apparently occurred in the mid-Cretaceous (Halpern and Rex, 1972; Dalziel et al., 1974; Wilson, 1991); however, the timing of the opening and closing of the basin is poorly constrained because of the scarcity of fossil evidence. So far, a Late Jurassic-Neocomian age was favored for the Yahgan Formation on the basis of the record of belemnites and ammonites (Aguirre Urreta and Suárez, 1985; Halpern and Rex, 1972; Winn, 1978). Halpern and Rex (1972) mentioned the Hauterivian genus Favrella in Gardiner Island, but this record has been questioned by Thomson et al. (1982) who considered the ammonite imprint to be some kind of heteromorph. Also, the timing of the transition from marginal to foreland basin is not well documented. On the basis of indirect evidence the initiation of the foreland basin stage was assigned to the Albian in the Ultima Esperanza region of Chile (Wilson, 1991) and to the Late Cretaceous in northern Tierra del Fuego (Biddle et al., 1986). Recent field work by the authors in the area of No Top Mountain-Moat River, Tierra del Fuego (Figure 1), has resulted in the first record of diagnostic late Albian inoceramids in the Yahgan Formation. The objective of this note is to document this fauna and to briefly discuss its implications on the control of the timing of the transition from marginal to foreland basin in the area.