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Sample records for andes northern chile

  1. Evolution of Parinacota volcano, Central Andes, Northern Chile

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    Jorge E. Clavero R.

    2004-12-01

    Full Text Available Parinacota is an active composite stratovolcano located in the Central Andes of Northern Chile (18°S. During its earlier stage (Parinacota 1 unit, Late Pleistocene, 300-70? ka rhyolitic to andesitic magmas were erupted, forming a voluminous lava-dome complex with its associated pyroclastic fans (mainly block-and-ash flow deposits, essentially deposited towards the Upper Lauca basin (West. It later evolved to a steep-sided composite stratocone (Parinacota 2 unit, Late Pleistocene-Holocene, 70?-8 ka, mainly formed by andesitic lava flows and scoria tephra fallout deposits.Around 8 ka ago the ancestral Parinacota volcano, built during Parinacota 1 and 2, partially collapsed towards the west, in a single and catastrophic event generating the outstanding Parinacota Debris Avalanche deposit.Soon after the collapse a new stratocone started to build with the emission of andesitic lava flows and pyroclastic flows, and their associated fallout deposits (Parinacota 3 unit, Holocene, La evolución del volcán Parinacota, Andes Centrales, norte de Chile. El volcán Parinacota es un estratovolcán activo ubicado en los Andes Centrales del norte de Chile (18°S. Durante su primera etapa de evolución (Unidad Parinacota 1, Pleistoceno Superior, 300-70? ka emitió magmas de composición riolítica a andesítica, formando un voluminoso complejo de lavas-domo con abanicos piroclásticos asociados (esencialmente depósitos de bloques y ceniza, distribuidos principalmente hacia la parte superior de la cuenca del río Lauca (oeste. Posteriormente, evolucionó a un estratocono compuesto, de fuertes pendientes (Unidad Parinacota 2, Pleistoceno-Holoceno, 70?-8 ka, formado principalmente por lavas y depósitos de caída andesíticos. Aproximadamente hace 8 ka el volcán Parinacota ancestral, construido durante las unidades Parinacota 1 y 2, colapsó parcialmente hacia el oeste, en un evento único y catastrófico generando el Depósito de Avalancha de Parinacota. Poco

  2. Constraints on sediment transfer from the Andes to the coast of northern Chile

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    Binnie, Steven; Liermann, Ariane; Dunai, Tibor; Dewald, Alfred; Heinze, Stefan

    2013-04-01

    While rates of denudation have been suggested as having the potential to link tectonic processes with climate in many settings, the roles that sediment transport must also play have been largely neglected. It is the transport, or not, of eroded material, not necessarily the rate at which that material is produced which is the critical factor in many models of tectonic-climatic interactions. The notable lack of sediment in sections of the Peru-Chile trench has been implicated as a key control of subduction zone processes and consequently Andean mountain building, but little empirical data on sediment transport in the region exists. Here, we present the initial results of a study aiming to constrain the westward transfer of sediment from the Andes Mountains to the Pacific Coast of northern Chile by using in situ-produced cosmogenic nuclides. Fluvial sediments were collected at the mouths of several large catchments between 19° S and 26° S, where they drain into the Pacific, and also from upstream locations within each catchment. Sample sites were selected in order to investigate the cosmogenic nuclide derived basin-averaged denudation rates of the western flank of the Andes, and to compare this with the cosmogenic nuclide concentrations of fluvial sediments further downstream where the catchments exit to the coast. A simplistic interpretation of the cosmogenic 10Be concentrations as denudation rates gives results varying between ~10 and 300 m/Myr. We would expect the most rapid erosion to occur on the steeper, wetter western Andean flank and for slower erosion to be recorded from the more gentle sloping, hyperarid/arid regions between the foothills of the Andes and the Pacific coast. This pattern is observed in some basins but in others the nuclide concentrations imply the opposite, with several-fold higher erosion rates measured for the large catchments sampled at the coast in comparison to their mountainous Andean headwaters. One explanation for this unusual

  3. Late Pleistocene glaciations of the arid subtropical Andes and new results from the Chajnantor Plateau, northern Chile

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    Ward, Dylan J.; Cesta, Jason M.; Galewsky, Joseph; Sagredo, Esteban

    2015-11-01

    The spatiotemporal pattern of glaciation along the Andes Mountains is an important proxy record reflecting the varying influence of global and regional circulation features on South American climate. However, the timing and extent of glaciation in key parts of the orogen, particularly the deglaciated arid Andes, are poorly constrained. We present new cosmogenic 10Be and 36Cl exposure ages for glacial features on and near the Chajnantor Plateau (23 °S). The new dates, although scattered due to cosmogenic inheritance, imply that the most recent extensive glacial occupation ended before or during the global Last Glacial Maximum (LGM). We discuss this new record in the context of published glacial chronologies from glacial features in Peru, Bolivia, and northern Chile rescaled using the latest cosmogenic 10Be production rate calibration for the tropical Andes. The results imply regionally synchronous moraine stabilization ca. 25-40 ka, 15-17 ka, and 12-14 ka, with the youngest of these moraines absent in records south of ˜20 °S, including in our new Chajnantor area chronology. This spatial pattern implicates easterly moisture in generating sufficient snowfall to glaciate the driest parts of the Andes, while allowing a role for westerly moisture, possibly modulated by the migration of the Southern Westerly Wind belt, in the regions near and south of the Atacama Desert.

  4. Tectonic styles and crustal shortening of the Central Andes "Pampean" flat-slab segment in northern Chile (27-29°S)

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    Martínez, Fernando; Arriagada, César; Peña, Matías; Deckart, Katja; Charrier, Reynaldo

    2016-01-01

    The Andean orogenic belt, located in the Central Andes "Pampean flat-slab" segment in northern Chile (27-29°S), is composed of two major tectonic regions: the Coastal Cordillera and the Frontal Cordillera. To understand their internal tectonic styles, history of growth and the shortening absorbed by the upper crustal structure of this segment, we combined regional geological mapping data, new ages obtained from radiometric U-Pb dating, and a semibalanced and restored cross-section 225.18 km in length. The results as shown in the previous Mesozoic extensional fault systems, established in northern Chile by the Gondwana breakup, have played a fundamental role in the orogenic buildup. The central structure is characterized by an asymmetric basin (Upper Cretaceous-Paleocene) confined by a doubly vergent fault system composed of inverted faults related to the edges of the Mesozoic Chañarcillo and Lautaro Basins. The U-Pb geochronological data obtained from synorogenic volcano-sedimentary deposits and the angular unconformities recorded between the Cenozoic geological units have revealed that the compressive deformation in this segment started at around ~ 80 Ma by tectonic inversion in the eastern Coastal Cordillera and western Frontal Cordillera, however, the presence of Paleocene and Miocene synorogenic successions at the footwall of the basement reverse faults of the Frontal Cordillera suggests a migration of Andean deformation from the west to the east during the Paleocene-Miocene by propagation of ramps involving inherited basement highs. The pre-compression restoration makes it possible to estimate 40.94 km of minimum shortening, concentrated by inversion anticlines and fault-controlled basement highs across the Frontal Cordillera.

  5. Síndrome pulmonar por hantavirus Andes en Chile CARDIOPULMONARY SYNDROME DUE TO ANDES VIRUS IN CHILE

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    CONSTANZA CASTILLO H.

    2002-01-01

    Full Text Available Desde 1993 han ocurrido 204 casos de Síndrome Cardiopulmonar por Hantavirus (SCPH en Chile. Los brotes epidémicos comenzaron en el sur y avanzan hacia el norte del país. Los más afectados son varones jóvenes, obreros agrícolas o forestales. En Chile, el SCPH es causado por el virus Andes, cuyo reservorio es el Oligorizomys longicaudatus (ratón de cola larga, que se distribuye desde la III Región al sur. El cuadro clínico es similar al descrito en EE.UU., caracterizado por una fase prodrómica que simula un estado gripal o cuadro gastrointestinal febril y que agrava por la aparición de edema pulmonar agudo e inestabilidad hemodinámica (fase cardiopulmonar. Sin embargo, cursa con mayores alteraciones hemorragí-paras y compromiso renal. La mortalidad inicial fue sobre 50% y actualmente es de alrededor del 33,3%. La presente revisión incluye: historia de la enfermedad, reservorio, modos de transmisión, patogenia, cuadro clínico, diagnóstico, tratamiento y medidas de prevenciónSince 1993, 204 cases of Hantavirus cardiopulmonary syndrome (HCPS occurred in Chile. Epidemic began in the south and moved thereafter to the northern regions. The disease affected predominantly young males, who worked in agricultural labours or as timber workers. The HCPS in Chile is caused by the Andes virus. The reservoir is the wild rat Oligoryzomis longicaudatus distributed from the III to the XII Region. The clinical features are similar to those described for Sin Nombre Virus. The disease has a prodromal stage characterised by fever, muscular pain, with or without gastrointestinal manifestations, followed by the rapid onset of respiratory insufficiency and haemodynamic unstability. Andes virus courses more often with haemorrhagic disorders and overt renal failure, than Sin Nombre Virus. The initial mortality was over 50% and declined to 33,3% in the last year. History of hantavirus-diseases, reservoir, and mode of contagion, pathogenesis, clinical

  6. Isotope hydrology in northern Chile

    International Nuclear Information System (INIS)

    Environmental isotope analyses were done on samples from aquifers in the Pampa del Tamarugal and the Salar de Atacama drainage basin in northern Chile. In the Pampa it is possible to delineate individual groundwater bodies on the basis of their 18O and deuterium contents and, in some cases, to relate these to specific recharge areas. A marked displacement from the meteoric water line indicates that river recharge is an important mechanism for groundwater renewal. Groundwater ages appear high at distance from the Andes and much of the water found in the Pampa may have to be treated as a non-renewable resource. The groundwaters, springs and rivers of the Salar de Atacama drainage basin vary between -6.09 and -8.06%. No difference between the different waters can be recognized and an evaporative isotope enrichment indicates that also here river recharge is an important process. Some groundwaters adjacent to the Salar are very salty but 18O and deuterium data show that these waters are not refluxed brines but simply salty freshwater. The 14C contents in groundwaters and springs are very low but their delta13C values are high. It is concluded that this is probably due to the uptake of volcanic CO2. 14C age dating is thus not possible unless the delta13C values of all possible carbon sources can be defined and the geochemical evolution of the groundwaters is better understood. (author)

  7. 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

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    F. Martínez

    2015-08-01

    Full Text Available 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.

  8. Geochronology (40Ar/39Ar, K-Ar and He-exposure ages of Cenozoic magmatic rocks from Northern Chile (18-22°S: implications for magmatism and tectonic evolution of the central Andes

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    Gerhard Wörner

    2000-12-01

    Full Text Available K-Ar and Ar/Ar ages from magmatic rocks of northern Chile (18-22°S describe duration and extent of the Tertiary and Quaternary magmatic evolution and date major tectonic events in northernmost Chile. This paper summarizes new K-Ar and Ar-Ar mineral and whole rock ages for intrusive rocks from the Precordillera, Tertiary ignimbrites and andesitic stratovolcanoes from the Western Andean Escarpment at 18°S (WARP and the volcanic front. Intrusive rocks of the Precordillera (Quebrada Paguana, Quebrada Blanca, Quebrada Choja, Quebrada Guatacondo, Cerro Chandacolla represent the Cretaceous to Eocene magmatic arc system and gave ages between 45 and 35 Ma. Younger ages on intrusive rocks are invariably caused by deuteric alteration. Ignimbrites of the Putani and Oxaya formations gave Ar-Ar sanidine ages around 24.2 to 24.8 Ma and 22.8 to 19.4 Ma, respectively. Andesitic stratovolcanoes, which directly overlie Oxaya ignimbrites east of the Western Cordillera gave ages of 20.3 Ma (Cordon Quevilque to 9.0 Ma (Cerro Margarita. Samples from the Miocene to Pleistocene arc system on the Chilean Altiplano underlying the volcanoes of the active volcanic front have been dated between 10.5 to ~3 Ma. A widespread ignimbrite can be correlated from the Lauca basin to the Pacific coast and to the east to occurrences of near Pérez. Repeated Ar-Ar sanidine dating of the Lauca-Pérez-ignimbrite resulted in highly concordant ages of 2.71±0.25 Ma, 2.72 Ma±0.01 Ma, and 2.73±0.11 Ma. Rocks from the active chain (Volcanic Cordillera gave ages younger than 0.9 Ma (Volcán Irruputuncu, Volcán Olca, Volcán Aucanquilcha, Volcán Ollagüe, Volcán Poruñita. These new data are used to constrain Miocene stratigraphy and tectonic movements as well as the timing of uplift and sedimentary response at the Western Andean Escarpment within the framework of the tectonic evolution of the Central AndesGeocronología (49Ar/39Ar, K-Ar y edades He de exposición de rocas cenozoicas del

  9. Late Mesozoic to Paleogene stratigraphy of the Salar de Atacama Basin, Antofagasta, Northern Chile: Implications for the tectonic evolution of the Central Andes

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    Mpodozis, Constantino; Arriagada, César; Basso, Matilde; Roperch, Pierrick; Cobbold, Peter; Reich, Martin

    2005-04-01

    The Salar de Atacama basin, the largest "pre-Andean" basin in Northern Chile, was formed in the early Late Cretaceous as a consequence of the tectonic closure and inversion of the Jurassic-Early Cretaceous Tarapacá back arc basin. Inversion led to uplift of the Cordillera de Domeyko (CD), a thick-skinned basement range bounded by a system of reverse faults and blind thrusts with alternating vergence along strike. The almost 6000-m-thick, upper Cretaceous to lower Paleocene sequences (Purilactis Group) infilling the Salar de Atacama basin reflects rapid local subsidence to the east of the CD. Its oldest outcropping unit (Tonel Formation) comprises more than 1000 m of continental red sandstones and evaporites, which began to accumulate as syntectonic growth strata during the initial stages of CD uplift. Tonel strata are capped by almost 3000 m of sandstones and conglomerates of western provenance, representing the sedimentary response to renewed pulses of tectonic shortening, which were deposited in alluvial fan, fluvial and eolian settings together with minor lacustrine mudstone (Purilactis Formation). These are covered by 500 m of coarse, proximal alluvial fan conglomerates (Barros Arana Formation). The top of the Purilactis Group consists of Maastrichtian-Danian alkaline lava and minor welded tuffs and red beds (Cerro Totola Formation: 70-64 Ma K/Ar) deposited during an interval of tectonic quiescence when the El Molino-Yacoraite Late Cretaceous sea covered large tracts of the nearby Altiplano-Puna domain. Limestones interbedded with the Totola volcanics indicate that this marine incursion advanced westwards to reach the eastern CD slope. CD shortening in the Late Cretaceous was accompanied by volcanism and continental sedimentation in fault bounded basins associated to strike slip along the north Chilean magmatic arc to the west of the CD domain, indicating that oblique plate convergence prevailed during the Late Cretaceous. Oblique convergence seems to have

  10. Miocene-Quaternary structural evolution of the Uyuni-Atacama region, Andes of Chile and Bolivia

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    Tibaldi, A.; Università degli Studi di Milano-Bicocca; Corazzato, C.; Università degli Studi di Milano-Bicocca; Rovida, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia

    2008-01-01

    We describe the Miocene-Quaternary geological-structural evolution of the region between the Salar de Uyuni and de Atacama, Andes of Chile and Bolivia. We recognised four main tectonic events based on fold geometry, fault kinematics and stratigraphic data. The oldest event, of Miocene age, is characterized by folding and reverse faulting of the sedimentary successions with an E-W direction of shortening in the northern part of the studied area and a WNW-ESE shortening in the southern part. Th...

  11. Evolución tectónica, paleogeográfica y metalogénica durante el Cenozoico en los Andes de Chile norte y central e implicaciones para las regiones adyacentes de Bolivia y Argentina Tectonic, paleogeographic, and metallogenic evolution during the Cenozoic in the Andes of Central and Northern Chile and implication for the adjacent regions of Bolivia and Argentina

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    Reynaldo Charrier

    2009-10-01

    southern Peru to central Chile and formed the boundary between two paleogeographical domains with dissimilar geological evolutions during the rest of the Cenozoic. The western domain was characterized by erosion and sedimentation processes. The eastern domain also included significant erosional episodes, but was characterized by different evolutions north and south of ~27°S. Northward of this latitude, within the Altiplano-Puna realm, the magmatic arc remained in a fixed position, coinciding with the current active arc, and was bordered by a back-arc foreland basin; whereas southward of ~27°S a succession of magmatic arcs developed with a prominent eastward migration. The Late Eocene to Late Oligocene- Early Miocene was characterized by the development of an extensive intra-arc extensional basin, the Abanico Basin. A succession of volcanic and volcaniclastic rocks, with minor sedimentary intercalations, up to 3,000 m thick were deposited within this basin. At about the boundary between the Oligocene and the Miocene a compressive tectonism affected the whole orogen rejuvenating the core of the Incaic Cordillera and resulted in the tectonic inversion of the Abanico Basin; leading to the syntectonic sedimentation on both sides of the new elevated terrain. The beginning of this tectonism is coincident with the Pehuenche orogeny, but the compression extended until the Early Pliocene. During the Early to Middle Miocene the deformation extended to the east with the development of foreland fold and thrust belts and basins. Within the western domain in northern Chile, area of the current Central Depression and Precordillera, the accumulation of thick sedimentary deposits from the western slope of the Incaic Cordillera originated the Tarapacá and Atacama pediments; whereas an extensive peneplanation developed in central Chile. In Late Miocene the prolonged development of the east-verging fold and thrust belts and the generation of overthrusts deep under the Cordillera, which

  12. Palaeoindian occupation of the Atacama Desert, northern Chile

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    Grosjean, Martin; Núñez, Lautaro; Cartajena, Isabel

    2005-10-01

    Palaeoindian occupation of the Atacama Desert in northern Chile has been found between 12 600 and 10 200 cal. yr BP. The new site at Salar Punta Negra (24°28S/60°53W/2976 m) includes about 1000 classifiable, mostly unifacial artefacts and, uniquely, three different diagnostic types of early projectile points. Two of the Lateglacial/early Holocene projectile types have wide distribution and are known from different geographical areas in South America: the Palaeoindian Fell fish-tail point mainly from the southern cone of South America, and the triangular Tuina points typical of the Puna of the south-central Andes in northern Chile and northwestern Argentina. In addition, we found a third type, a stemmed point typical for the Salar Punta Negra. Filling a large geographical gap of Fell occupation, the site at Salar Punta Negra provides evidence for generally much higher mobility and diversity of early cultures, and supports an Andean-Pacific route for early human exploration of South America to the south through the desert at intermediate altitudes. Contemporaneous high-amplitude climatic changes were fundamental preconditions to provide adequate environments and habitats, and to make Palaeoindian hunting-gathering occupation possible in the Atacama Desert.

  13. Isotopic composition and origin of the precipitation in Northern Chile

    Energy Technology Data Exchange (ETDEWEB)

    Aravena, R. [Department of Earth Sciences, University of Waterloo, Waterloo (Canada); Suzuki, O. [Exploracion y Desarrollo de Recursos Hidricos, Santiago (Chile); Pena, H. [Direccion General de Aguas, Ministerio de Obras Publicas, Santiago (Chile); Pollastri, A. [Comision Chilena de Energia Nuclear, Santiago (Chile); Fuenzalida, H. [Departamento de Geofisica, Universidad of Chile, Santiago (Chile); Grilli, A. [Empresa Metropolitana de Obras Sanitarias, Santiago (Chile)

    1999-06-01

    A 3 a data set of isotopes in precipitation from northern Chile show a very distinct pattern, with {delta}{sup 18}O values ranging between -18 and -15per thousand at high altitude stations, compared to {delta}{sup 18}O values between -10 and -6per thousand at the lower altitude areas. The {sup 18}O-depleted values observed in the high altitude area, the Altiplano, are related to processes that affect the air masses that originated over the Atlantic, cross the Amazon Basin (continental effect), ascend the Andes (altitude effect) and precipitated (convective effect) in the Altiplano. It is postulated that a second source of moisture, associated with air masses from the Pacific, may contribute to the {sup 18}O-enriched values observed in the lower altitude areas. Similar isotopic patterns are documented in springs and groundwater indicating that the data presented in this paper are an accurate representation of the long term behavior isotopic composition of rain in northern Chile. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  14. Evolución tectónica, paleogeográfica y metalogénica durante el Cenozoico en los Andes de Chile norte y central e implicaciones para las regiones adyacentes de Bolivia y Argentina Tectonic, paleogeographic, and metallogenic evolution during the Cenozoic in the Andes of Central and Northern Chile and implication for the adjacent regions of Bolivia and Argentina

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    Reynaldo Charrier; Marcelo Farías; Víctor Maksaev

    2009-01-01

    La orogenia incaica dio origen a un importante relieve en el Eoceno Medio, el que se concentró en el ámbito del arco magmático precedente, la Cordillera Incaica. Este relieve positivo de orientación NNE se extendió desde el sur de Perú hasta la región central de Chile y separó dos dominios paleogeográficos que tuvieron evoluciones diferentes durante el resto del Cenozoico. El dominio occidental se caracterizó por el predominio de procesos de erosión y sedimentación. En el dominio oriental tam...

  15. Glacier contribution to streamflow in two headwaters of the Huasco River, Dry Andes of Chile

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    Gascoin, S.; C. Kinnard; R. Ponce; S. Lhermitte; MacDonell, S; A. Rabatel

    2010-01-01

    Quantitative assessment of glacier contribution to present-day streamflow is a prerequisite to the anticipation of climate change impact on water resources in the Dry Andes. In this paper we focus on two glaciated headwater catchments of the Huasco Basin (Chile, 29° S). The combination of glacier monitoring data for five glaciers (Toro 1, Toro 2, Esperanza, Guanaco, Estrecho and Ortigas) with five automatic streamflow records at sites with glacier coverage of 0.4 to 11% allows the estimation ...

  16. Revisiting mountain-building in the Andes of Central Chile: constraints from structural geology and thermochronology.

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    Riesner, M.; Lacassin, R.; Simoes, M.; Armijo, R.; Carrizo, D.

    2015-12-01

    The Andes, one of the most significant reliefs on Earth, is the case example of a subduction-type mountain belt. In central Chile and western Argentina, the particular east-vergent structure of the Aconcagua fold-and-thrust belt (AFTB) is found atop a huge basement high with elevations > 4000 m, the Frontal Cordillera. Classical conceptual models consider the Andes as an east-vergent orogen, opposite to the Nazca subduction, and describe the exhumation of the Frontal Cordillera as an eastward in-sequence event that occurred late in the andean deformation (by ~10My). An alternative model recently challenged this view by proposing that the Andes have mainly a primary westward vergence. Within this scheme, the exhumation of the Frontal Cordillera would have begun earlier, by ~25My, synchronous with formation of the AFTB on the western side of the basement high. Here we test these two models by revisiting structural cross-sections of the Andes at the latitude of Santiago de Chile and of the Aconcagua (~33°S). We provide thermochronological constraints on the timing of exhumation of the Frontal Cordillera by (U-Th)/He dating on apatites retrieved from paleozoic granitoids along a 2,3km high nearly vertical section in the core of the basement high. Preliminary results suggest that the Frontal Cordillera exhumation was not a late event and likely began around 25 Ma. Therefore it appears to be synchronous with deformation within the AFTB and the westernmost fold-and-thrust belt at this latitude. We discuss these results and their implications while building a crustal-scale cross section of the range at the latitude of Santiago de Chile.

  17. Miocene-Quaternary structural evolution of the Uyuni-Atacama region, Andes of Chile and Bolivia

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    Tibaldi, A.; Corazzato, C.; Rovida, A.

    2009-06-01

    We describe the Miocene-Quaternary geological-structural evolution of the region between the Salar de Uyuni and de Atacama, Andes of Chile and Bolivia. We recognized four main tectonic events based on fold geometry, fault kinematics and stratigraphic data. The oldest event, of Miocene age, is characterized by folding and reverse faulting of the sedimentary successions with an E-W direction of shortening in the northern part of the studied area and a WNW-ESE shortening in the southern part. The following two events, of Pliocene age, are characterized by lower shortening amounts; they occurred first by reverse faulting with a NW-SE-trending greatest principal stress ( σ1, computed with striated fault planes) and a vertical least principal stress ( σ3), followed by pervasive strike-slip faulting with the same NW-SE-trending σ1 and a horizontal NE-SW σ3. The fourth event, dating to the late Pliocene-Quaternary is characterized by normal faulting: the σ3 still trends NE-SW, whereas the intermediate principal stress σ2 exchanged with σ1. Volcanism accompanied both the contractional, transcurrent and extensional tectonic phases. The Mio-Pliocene compression appears directly linked to a rapid convergence and an apparently important coupling between the continental and oceanic plates. The E-W to WNW-ESE direction of shortening of the Miocene structures and the NW-SE σ1 of the Pliocene structures seem to be more linked to an intra-Andean re-orientation of structures following the WNW-directed absolute motion of the South-American Plate. The extensional deformations can be interpreted as related to gravity forces affecting the highest parts of the volcanic belt in a sort of asymmetrical (SW-ward) collapse of the belt.

  18. Reconstruction of cryospheric changes in the Maipo and Juncal river basins, central Andes of Chile: an integrative geomorphological approach

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    Nussbaumer, Samuel U.; García, Juan L.; Gómez, Gabriel; Vega, Rodrigo M.; Gärtner-Roer, Isabelle; Salzmann, Nadine

    2016-04-01

    glaciers diminished in thickness without significant retreat of the glacier front. Another geomorphological feature identified is the separation of ice facies, from dynamically flowing ice with an active ice front, to dead ice covered by debris. In parallel, paraglacial processes affect the morphology of the moraines. The central Andes are a climatically very sensitive zone between the southern humid and northern arid Andes, embracing a key location for uncovering past migration of the southern westerlies, the main driver of local climate variability. Understanding ice variability in the semi-arid Andes of Chile during past centuries (i.e., pre-instrumental time) can provide the urgent climate background context before the 20th/21st-century global warming and from here to assess local atmosphere-cryosphere linkages. This multifarious, patrimonial natural heritage and geological archive in the central Andes is nowadays not only threatened by climatic change but also human activities (e.g., mining).

  19. Apacheta, a new geothermal prospect in Northern Chile

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    Urzua, Luis; Powell, Tom; Cumming, William B.; Dobson, Patrick

    2002-05-24

    The discovery of two high-temperature fumaroles, with gas geochemistry compatible with an economic geothermal system, established Apacheta as one of the most attractive geothermal exploration prospects in northern Chile. These remote fumaroles at 5,150 m elevation were first sampled in 1999 by ENAP and its partners, following up on the reports of a CODELCO water exploration well that flowed small amounts of dry steam at 4,540 m elevation in the valley 4.5 km east of the fumaroles. The prospect is associated with a Plio-Pleistocene volcanic complex located within a NW-trending graben along the axis of the high Andes. The regional water table is 4,200 masl. There are no hot springs, just the 88 degrees C steam well and the 109 degrees and 118 degrees C fumaroles with gas compositions that indicate reservoir temperatures of greater than or equal to 250 degrees C, using a variety of gas geothermometers. An MT-TDEM survey was completed in 2001-2002 by Geotermica del Norte (SDN), an ENAP-C ODELCO partnership, to explore the Apacheta geothermal concession. The survey results indicated that base of the low resistivity clay cap has a structural apex just west of the fumaroles, a pattern typically associated with shallow permeability within a high temperature geothermal resource. SGN plans to drill at least one exploration well in 2002-03 to characterize a possible economic resource at Apacheta.

  20. An elusive new species of Marsupial Frog (Anura: Hemiphractidae: Gastrotheca from the Andes of northern Peru

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    William E. Duellman

    2013-06-01

    Full Text Available A new species of marsupial frog, genus Gastrotheca, is described from high-elevation grasslands in the Andes in Región Amazonas in northernPeru, where even calling males are well hidden in deep moss. The new species is distinguished from all congeners by its unique color pattern that includes a narrow, blackbordered, yellow middorsal stripe. The species apparently belongs to the Gastrotheca plumbea Group, which ranges in the Andes from northern Colombia to northern Peru.

  1. Chile.

    Science.gov (United States)

    1988-09-01

    Chile is a long (2650 miles), narrow (250 miles at widest point) country sandwiched between the Andes mountains and the Pacific. The northern desert is rich in copper and nitrates; the temperate middle region is agricultural and supports the major cities, including Santiago, the capital, and the port of Valparaiso; and the southern region is a cold and damp area of forests, grasslands, lakes, and fjords. The country is divided into 12 administrative regions. Chile's population of 12.5 million are mainly of Spanish or Indian descent or mestizos. Literacy is 92.3%, and the national language is Spanish. Infant mortality is 18.1/1000, and life expectancy is 68.2 years. 82% of the people are urban, and most are Roman Catholics. Chile was settled by the Spanish in 1541 and attached to the Viceroyalty of Peru. Independence was won in 1818 under the leadership of Bernardo O'Higgins. In the 1880s Chile extended its sovereignty over the Strait of Magellan in the south and areas of southern Peru and Bolivia in the north. An officially parliamentary government, elected by universal suffrage, drifted into oligarchy and finally into a military dictatorship under Carlos Ibanez in 1924. Constitutional government was restored in 1932. The Christian Democratic government of Eduardo Frei (1964-70) inaugurated major reforms, including land redistribution, education, and far-reaching social and economic policies. A Marxist government under Salvador Allende lasted from 1970 to 1973 when the present military government of General Pinochet Ugarte took power, overthrew Allende, abolished the Congress, and banned political parties. It has moved the country in the direction of a free market economy but at the cost of systematic violations of human rights. A new constitution was promulgated in 1981, and congressional elections have been scheduled for October, 1989. A "National Accord for Transition to Full Democracy" was mediated by the Catholic Church in 1985. The social reforms of the

  2. Subduction zone guided waves in Northern Chile

    Science.gov (United States)

    Garth, Thomas; Rietbrock, Andreas

    2016-04-01

    Guided wave dispersion is observed in subduction zones as high frequency energy is retained and delayed by low velocity structure in the subducting slab, while lower frequency energy is able to travel at the faster velocities associated with the surrounding mantle material. As subduction zone guided waves spend longer interacting with the low velocity structure of the slab than any other seismic phase, they have a unique capability to resolve these low velocity structures. In Northern Chile, guided wave arrivals are clearly observed on two stations in the Chilean fore-arc on permanent stations of the IPOC network. High frequency (> 5 Hz) P-wave arrivals are delayed by approximately 2 seconds compared to the low frequency (times of different frequencies, while the velocity spectra is used to constrain the relative amplitude of the arrivals. Constraining the waveform in these two ways means that the full waveform is also matched, and the low pass filtered observed and synthetic waveforms can be compared. A combined misfit between synthetic and observed waveforms is then calculated following Garth & Rietbrock (2014). Based on this misfit criterion we constrain the velocity model by using a grid search approach. Modelling the guided wave arrivals suggest that the observed dispersion cannot be solely accounted for by a single low velocity layer as suggested by previous guided wave studies. Including dipping low velocity normal fault structures in the synthetic model not only accounts for the observed strong P-wave coda, but also produces a clear first motion dispersion. We therefore propose that the lithospheric mantle of the subducting Nazca plate is highly hydrated at intermediate depths by dipping low velocity normal faults. Additionally, we show that the low velocity oceanic crust persists to depths of up to 200 km, well beyond the depth range where the eclogite transition is expected to have occurred. Our results suggest that young subducting lithosphere also has

  3. Classification of debris-covered glaciers and rock glaciers in the Andes of central Chile

    Science.gov (United States)

    Janke, Jason R.; Bellisario, Antonio C.; Ferrando, Francisco A.

    2015-07-01

    In the Dry Andes of Chile (17 to 35° S), debris-covered glaciers and rock glaciers are differentiated from true glaciers based on the percentage of surface debris cover, thickness of surface debris, and ice content. Internal ice is preserved by an insulating cover of thick debris, which acts as a storage reservoir to release water during the summer and early fall. These landforms are more numerous than glaciers in the central Andes; however, the existing legislation only recognizes uncovered or semicovered glaciers as a water resource. Glaciers, debris-covered glaciers, and rock glaciers are being altered or removed by mining operations to extract valuable minerals from the mountains. In addition, agricultural expansion and population growth in this region have placed additional demands on water resources. In a warmer climate, as glaciers recede and seasonal water availability becomes condensed over the course of a snowmelt season, rock glaciers and debris-covered glaciers contribute a larger component of base flow to rivers and streams. As a result, identifying and locating these features to implement sustainable regional planning for water resources is important. The objective of this study is to develop a classification system to identify debris-covered glaciers and rock glaciers based on the interpretation of satellite imagery and aerial photographs. The classification system is linked to field observations and measurements of ice content. Debris-covered glaciers have three subclasses: surface coverage of semi (class 1) and fully covered (class 2) glaciers differentiates the first two forms, whereas debris thickness is critical for class 3 when glaciers become buried with more than 3 m of surface debris. Based on field observations, the amount of ice decreases from more than 85%, to 65-85%, to 45-65% for semi, fully, and buried debris-covered glaciers, respectively. Rock glaciers are characterized by three stages. Class 4 rock glaciers have pronounced

  4. Meteorological drivers of ablation processes on a cold glacier in the semiarid Andes of Chile

    Directory of Open Access Journals (Sweden)

    S. MacDonell

    2013-04-01

    Full Text Available Meteorological and surface change measurements collected during a 2.5 yr period are used to calculate surface mass and energy balances at 5324 m a.s.l. on Guanaco Glacier, a cold-based glacier in the semi-arid Andes of Chile. Meteorological conditions are marked by extremely low vapour pressures (annual mean of 1.1 hPa, strong winds (annual mean of 10 m s−1, high shortwave radiation receipt (mean annual 295 W m−2 and low precipitation rates (mean annual 45 mm w.e.. Net shortwave radiation provides the greatest source of energy to the glacier surface, and net longwave radiation dominates energy losses. The turbulent latent heat flux is always negative, which means that the surface is always losing mass via sublimation, which is the main form of ablation at the site. Sublimation rates are most strongly correlated with net shortwave radiation, incoming shortwave radiation, albedo and vapour pressure. Low glacier surface temperatures restrict melting for much of the period, however episodic melting occurs during the austral summer, when warm, humid, calm and high pressure conditions restrict sublimation and make more energy available for melting. Low accumulation (131 mm w.e. over the period and relatively high ablation (1435 mm w.e. means that mass change over the period was negative (−1304 mm w.e., which continued the negative trend recorded in the region over the last few decades.

  5. Parameterisation of incoming longwave radiation over glacier surfaces in the semiarid Andes of Chile

    Science.gov (United States)

    MacDonell, Shelley; Nicholson, Lindsey; Kinnard, Christophe

    2013-02-01

    A good understanding of radiation fluxes is important for calculating energy, and hence, mass exchange at glacier surfaces. This study evaluates incoming longwave radiation measured at two nearby glacier stations in the high Andes of the Norte Chico region of Chile. These data are the first published records of atmospheric longwave radiation measurements in this region. Nine previously published optimised parameterisations for clear sky emissivity all produced results with a root mean square error (RMSE) ~20 W m-2 and bias within ±5 W m-2, which is inline with findings from other regions. Six optimised parameterisations for incoming longwave in all sky conditions were trialled for application to this site, five of which performed comparably well with RMSE on daytime data <18 W m-2 and bias within ±6 W m-2 when applied to the optimisation site and RMSE <20 W m-2 and bias within ±10 W m-2 when applied to the validation site. The parameterisation proposed by Mölg et al. (J Glaciol 55:292-302, 2009) was selected for use in this region. Incorporating the proposed elevation modification into the equation reduced the bias in the modelled incoming longwave radiation for the validation site. It was found that applying the parameterisation optimised in the original work at Kilimanjaro produced good results at both the primary and validation site in this study, suggesting that this formulation may be robust for different high mountain regions.

  6. Isotopic evolution of aqueous sulphate in northern Chile water

    International Nuclear Information System (INIS)

    Full text: The extremely arid condition of northern Chile is the main obstacle to the present and future development of urban centres and economic activities in the region. The existing water resources are scarce. During the last decade, isotope techniques have been applied to investigate aspects such as the origin and residence time of the groundwater, these being extremely important for water development and water management. This paper presents 18O and 34S data in aqueous sulphate, as well as 18O, 2H, and 3H from springs, rivers and groundwater samples of the Pampa del Tamarugal and Salar de Llamara basins. The principal aim of this study was to investigate the isotope evolution of the sulphate, the origin of the sulphur, the groundwater flow path, and the possibility of using the 18O of the sulphate as a tracer for estimation of the residence time of the groundwater. Springs that have their recharge area in the high Altiplano (Salar del Huasco basin) show δ values between +5.0 per mille and +6.0 per mille for the 18O and +5.0 per mille and +9.0 per mille for the 34S isotope. Springs from lower altitude, show an isotope content between + 8.6 per mille and + 10.6 per mille for 18O and +7.4 per mille and + 11.7 per mille for 34S. The groundwaters in the Pampa aquifers, based on their hydrogen and oxygen isotope composition, are associated with different recharge areas. However, these waters show an isotope range for the sulphate similar to .he one of the springs, and no clear relationships are observed between isotope content, flow path and residence time. This pattern could be related to the poorly defined aquifer systems present in the Pampa. The Llamara groundwaters have a uniform isotope content and are the most enriched in the region (δ18O = -6.0 per mille and δ2H = -50 per mille). The isotope composition of their sulphate compares well with the Pampa groundwater, indicating a similar sulphate source. The isotope composition of gypsum deposits in the

  7. Is tourism damaging ecosystems in the Andes? Current knowledge and an agenda for future research

    OpenAIRE

    Barros, Agustina; Monz, Christopher; Pickering, Catherine

    2014-01-01

    Despite the popularity of tourism and recreation in the Andes in South America and the regions conservation value, there is limited research on the ecological impacts of these types of anthropogenic use. Using a systematic quantitative literature review method, we found 47 recreation ecology studies from the Andes, 25 of which used an experimental design. Most of these were from the Southern Andes in Argentina (13 studies) or Chile (eight studies) with only four studies from the Northern Ande...

  8. Large slope instabilities in Northern Chile and Southern Peru

    Science.gov (United States)

    Crosta, Giovanni B.; Hermanns, Reginald L.; Valbuzzi, Elena; Frattini, Paolo; Valagussa, Andrea

    2014-05-01

    Deep canyon incision into Tertiary paleosurfaces and large slope instabilities along the canyon flanks characterize the landscape of western slope of the Andes of northern Chile and South Peru. This area belongs to the Coastal Escarpment and Precordillera and is formed by coarse-grained clastic and volcanoclastic formations. The area is characterized by intense seismicity and long-term hyperaridity (Atacama Desert). Landslides along the canyon flanks affect volumes generally up to 1 km3 and locally evolved in large rock avalanches. We prepared a landslide inventory covering an area of about 30,000 km2, extending from Iquique (Chile) to the South and Tacna (Peru) to the North. A total of 606 landslides have been mapped in the area by use of satellite images and direct field surveys, prevalently including large phenomena. The landslides range from 1 10-3 km2 to 464 km2 (Lluta landslide). The total landslide area, inclusive of the landslide scarp and of the deposit, amounts to about 2,130 km2 (about 7% of the area). The mega landslides can be classified as large block slides that can evolve in large rock avalanches (e.g. Minimini landslide). Their initiation seems to be strongly associated to the presence of secondary faults and large fractures transversal to the slope. These landslides show evidence suggesting a re-incision by the main canyon network. This seems particularly true for the Lluta collapse where the main 'landslide' mass is masked or deleted by the successive erosion. Other landslides have been mapped along the Coastal Escarpment and some of the major tectonic escarpments with an E-W trend. We examined area-frequency distributions of landslides by developing logarithmically binned, non-cumulative size frequency distributions that report frequency density as a function of landslide planar area A. The size frequency distribution presents a strong undersampling for smaller landslides, due to the extremely old age of the inventory. For landslides larger than

  9. Cenozoic foreland-basin evolution in the northern Andes : insights from thermochronology and basin analysis in the Eastern Cordillera, Colombia

    OpenAIRE

    Parra, Mauricio

    2009-01-01

    The modern foreland basin straddling the eastern margin of the Andean orogen is the prime example of a retro-arc foreland basin system adjacent to a subduction orogen. While widely studied in the central and southern Andes, the spatial and temporal evolution of the Cenozoic foreland basin system in the northern Andes has received considerably less attention. This is in part due to the complex geodynamic boundary conditions, such as the oblique subduction and accretion of the Caribbean plates ...

  10. Altitudinal vegetation belts in the high-Andes of central Chile (33°S Pisos altitudinales de vegetación en los Andes de Chile central (33°S

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    Lohengrin A. Cavieres

    2000-06-01

    Full Text Available The limits of alpine vegetation belts have been established mainly based on physiognomic criteria. However, a more objective approach for fixing limits of vegetation belts are methods based on species composition and relative abundance of each species. While these methods are more time consuming, they are more detailed and permit the detection of physical factors affecting the limits of vegetation belts. In this paper we: 1 describe the altitudinal changes of vegetation above timberline, 2 compare vegetation belts defined with physiognomy and two floristic methods (a qualitative one based on altitudinal changes in species composition, and a quantitative one based on changes in dominant species; and 3 detect some environmental factors responsible for the altitudinal distribution of alpine vegetation between 2100 and 3700 masl in the Andes of Santiago, central Chile (33°S. There was a complete agreement between the different methods in delimiting the subalpine belt. However, in the lower alpine belt (the cushion's belt floristic methods subdivided it in 2-3 sub-belts. In the floristic methods, elevations 3500-3700 that formed the higher alpine belt segregated in separate ways because they have no species in common. Physiognomic descriptions lose relevant information about species distribution, especially at higher elevations. Mean annual temperature and nitrogen content of soil are the main environmental factors affecting the altitudinal limits of vegetation belts in the central Chilean AndesLa delimitación de los pisos altitudinales de vegetación andina se ha basado principalmente en criterios fisionómicos. Sin embargo, un criterio más objetivo para la delimitación es usar métodos basados en la composición y abundancia relativa de las especies presentes. Mientras estos métodos requieren de un mayor esfuerzo de muestreo, son más detallados y permiten detectar factores físicos involucrados en la delimitación altitudinal de la vegetaci

  11. Oral health in prehistoric San Pedro de Atacama oases, Northern Chile.

    Science.gov (United States)

    Oliveira, R E; Neves, W A

    2015-12-01

    After almost 2000 years of local development, including limited trading with neighboring ethnic groups, the societies that occupied the oases of San Pedro de Atacama, Northern Chile, became part of the trade web of the Tiwanaku empire, between 500 and 1000 CE. Archaeological evidence tends to support the idea that the period under the influence of the altiplano (high plane) empire was very affluent. Here we investigate the possibility that this affluence had a positive impact on the health status of the Atacameneans, using the oral health as an indirect indicator of quality of life. Dental decay, dental abscess, dental wear, linear enamel hypoplasia, periodontal disease and dental calculus were analyzed on 371 skeletons from 12 sites from San Pedro de Atacama oases. We believe that if, indeed, there were better biological conditions during the altiplano influence, this could have been caused by the access to a more diversified food intake promoted by the intensification of the trading network established by Tiwanaku in the central-south Andes, of which San Pedro de Atacama became an important node. PMID:26253130

  12. Assessing giant tsunamigenic subduction earthquakes in the Northern Chile Seismic Gap during the last two millennia

    Science.gov (United States)

    Vargas Easton, G.; Ruiz, S.; Leyton, F.; Abrahami, R.; Le Roux, J.; Pantoja, S.; Lange, C.; Contreras Reyes, E.; Campos, J. A.

    2014-12-01

    Marine sedimentary records off Northern Chile provide a new view about the occurrence of large subduction earthquakes along the hyperarid convergent margin of the Central Andes. From high resolution geochronology and sedimentology of laminated series accumulated on narrow shelf, we observed that anomalous structures such as slumps and discontinuities overlaid by turbidite deposits record the last giant Mw~8.8 earthquake and tsunami occurred on 1877 in the region. Once compared with the reanalysis of historical chronicles and seismological data, we suggest that only large magnitude events produce ground accelerations generating slumping or discontinuities. The analysis of long (ca. 5.5 m) sediment cores together with high resolution seismic subbottom profile data allow us to infer the occurrence of several giant earthquakes in the last ca. 1600 years, with a mean recurrence in the order of 400 years. Under this scope, the Mw8.1 occurred this year off Pisagua-Iquique region, as other previous historic events (Mw7.7, Tocopilla, 2007; Mw7.6, Iquique, 1933), seem to be moderate earthquakes into a larger seismic cycle.

  13. Fluvio-lacustrine sedimentation and volcanism in a Late Carboniferous tensional intra-arc basin, northern Chile

    Science.gov (United States)

    Breitkreuz, Christoph

    1991-11-01

    Extensive outcrops of Late Carboniferous to Triassic volcanoplutonic magnetic-arc complexes occur in the Andes of northern Chile. In the Salar de Atacama area, terrestrial volcanosedimentary successions include a 200-600 m thick fluvio-lacustrine sequence ("Miembro Medio"). The terrestrial basin which accommodated this sequence formed during the latest Carboniferous on top of the deposits of the pre-existing Carboniferous composite volcanoes. The lower part of the Miembro Medio consists of green limnic and multicoloured alluvial fan deposits; the upper part is made up of red fluvial sedimentary rocks. Basic volcanic rocks occur locally throughout the sequence. The climate is inferred to have been warm and humid. The limnic (freshwater) environment had a minimum extension of 300 × 100 km. Limnic facies is inferred from the existence of fine-parallel-bedded sediments, ooliths and a limnic benthic fauna. Lake-shore deposits prevail in the outcrops. In some sections, the green limnic sequence is followed by red fine-grained floodplain or alluvial plain, and fluvial channel deposits. The framework composition of the Miembro Medio is dominated by volcanogenic detritus presumably eroded from the successions of the previous Late Carboniferous volcanic arc. Another volcanogenic clast type was provided by syndepositional basalto-andesitic phreatomagmatic activity, which also produced peperitic sills, dykes and lavas. The limnic-alluvial fan facies association, the predominance of volcanogenic detritus, and the accompanying intrabasinal basic calc-alkaline volcanism together with the considerable size of the basin point to a ?NW-SE trending half-graben setting controlled by (trans-)tensional arc tectonics. With regard to the Late Carboniferous-Triassic volcanosedimentary successions of northern Chile, this Latest Carboniferous tensional setting is the only feature in this area supporting those models, which inferred an extensional magmatic arc for the entire Central and

  14. Land Use Change and Hydrologic Processes in High-Elevation Tropical Watersheds of the Northern Andes

    Science.gov (United States)

    Avery, W. A.; Riveros-Iregui, D. A.; Covino, T. P.; Peña, C.

    2013-12-01

    The humid tropics cover one-fifth of the Earth's land surface and generate the greatest amount of runoff of any biome globally, but remain poorly understood and understudied. Humid tropical regions of the northern and central Andes have experienced greater anthropogenic land-use/land-cover (LULC) change than nearly any other high mountain system in the world. Vast expanses of this region are currently undergoing rapid transformation to farmland for production of potatoes and pasture for cattle grazing. Although the humid tropics have some of the highest runoff ratios, precipitation, and largest river flows in the world, there is a lack of scientific literature that addresses hydrologic processes in these regions and very few field observations are available to inform management strategies to ensure the sustainability of water resources of present and future generations. We seek to improve understanding of hydrologic processes and feedbacks in the humid tropics using existing and new information from two high-elevation watersheds that span a LULC gradient in the Andes Mountains of Colombia. One site is located in the preserved Chingaza Natural National Park in Central Colombia (undisturbed). The second site is located ~60 km to the northwest and has experienced considerable LULC change over the last 40 years. Combined, these watersheds deliver over 80% of the water resources to Bogotá and neighboring communities. These watersheds have similar climatological characteristics (including annual precipitation), but have strong differences in LULC which result in substantial differences in hydrologic response and streamflow dynamics. We present an overview of many of the pressing issues and effects that land degradation and climate change are posing to the long-term sustainability of water resources in the northern Andes. Our overarching goal is to provide process-based knowledge that will be useful to prevent, mitigate, or respond to future water crises along the Andean

  15. Pluri-decadal (1955–2014) evolution of glacier–rock glacier transitional landforms in the central Andes of Chile (30–33° S)

    OpenAIRE

    Monnier, S.; C. Kinnard

    2016-01-01

    This study deals with relationships between debris-covered glaciers and rock glaciers in the central Andes of Chile. Three glacier–rock glacier transitional landforms are investigated over the last decades in order to highlight and question the significance of their landscape evolution and dynamics. We use series of historical air photos and Geoeye satellite images together with common remote sensing operations including imagery orthorectification, digital elevation model generation, an...

  16. A study of the energy balance and melt regime on Juncal Norte Glacier, semi-arid Andes of central Chile, using melt models of different complexity

    OpenAIRE

    Pellicciotti, Francesca; Helbing, Jakob; Rivera, Andrés; Favier, Vincent; Corripio, Javier; Araos, José; Sicart, Jean-Emmanuel; Carenzo, Marco

    2008-01-01

    We use meteorological data from two automatic weather stations (AWS) on Juncal Norte Glacier, central Chile, to investigate the glacier-climate interaction and to test ablation models of different complexity. The semi-arid Central Andes are characterized by dry summers, with precipitation close to zero, low relative humidity and intense solar radiation. We show that katabatic forcing is dominant both on the glacier tongue and in the fore field, and that low humidity and absence of clouds caus...

  17. Oxygenation variability off Northern Chile during the last two centuries

    Directory of Open Access Journals (Sweden)

    J. A. Díaz-Ochoa

    2010-07-01

    Full Text Available The Peru Chile Current ecosystem is characterized by high biological productivity and important fisheries. Although this system is likely to be severely affected by climate change, its response to current global warming is still uncertain. In this paper we analyze 10–166 year old sediments in two cores collected in Mejillones Bay, an anoxic sedimentary setting favorable for preservation of proxies. Based on a 166 year chronology we used indicators of bottom water oxygenation proxies (Mo, V, S, and the (lycopane+n-C35/n-C31 ratio and surface water productivity (biogenic opal, counts of diatom valves, biogenic Ba, organic carbon and chlorins to reconstruct environmental variations in Mejillones Bay. We find that at decadal scales, and during the last two centuries, a shift in the coastal marine ecosystem off Northern Chile took place which was characterized by intense ENSO-like activity and large fluctuations in biological export productivity, in bottom water oxygenation, and increased eolic activity (inferred from Ti/Al and Zr/Al. On top of this short-term variability, a gradual increase of sulfidic conditions has occurred being even more intensified since the early 1960s.

  18. Site testing for the VLT in Northern Chile

    Science.gov (United States)

    Woltjer, L.

    The European Southern Observatory (ESO) will need sites for three telescopes. The telescopes considered include the 3.5 m New Technology Telescope to be completed in 1987, the 15 m Swedish-ESO mm/submm telescope, and the Very Large Telescope (VLT). The first two telescopes will probably be placed on La Silla. However, because of humidity considerations, a later transfer of the 15 m mm/submm telescope to a drier site appears possible. The main reason for conducting a new site survey is related to the VLT. Possible areas for establishing an observatory in the Southern Hemisphere are examined, taking into account Northern Chile. Attention is given to an area south of Antofagasta, mountains west of the Salar de Punta Negra, mountains between San Pedro de Atacama and El Tatio, mountains east of La Silla, problems regarding the observation of faint objects, water vapor content, and difficulties due to wind.

  19. Trophic interactions in northern Chile upwelling ecosystem, year 1997

    Directory of Open Access Journals (Sweden)

    Mónica E Barros

    2014-11-01

    Full Text Available A food web model is constructed to describe predator-prey interactions, community structure and trophic flows in northern Chile upwelling ecosystem (18°20'S, 24°S, for the year 1997. The model is built using the Ecopath with Ecosim software version 6.4, and encompasses 21 functional groups, ranging from primary producers (phytoplankton to top predators (birds and marine mammals, the principal fishing resources and the fishery. Input parameters required to build the model were gathered from specialized literature, grey literature and our own estimates. The results indicated that the total biomass (B T was estimated at 624.7 ton km-2. The combined biomass of small pelagic fish represented 26% of B T, while the combined biomass of demersal fish represented only 0.1% of B T. These results highlight the importance of pelagic fish in this system. Predation mortality resulted to be the main source of mortality. Nevertheless, fishing mortality was important in anchovy, mackerel, common dolphinfish and jack mackerel. The mean trophic level of the fishery was estimated as 3.7, with landings sustained mainly by anchovy. Primary production required to sustain the landings (PPR was estimated at 7.5% of calculated total net primary production, which is lower than PPR estimates in other upwelling ecosystems. The average trophic transfer efficiency was 18%, which is in the range (10-20% informed for marine ecosystems. Results indicate that in 1997 the northern Chile marine ecosystem was characterized for being a system far from maturity, dominated in terms of biomass and flows by the pelagic realm.

  20. A new species of Eupithecia Curtis (Lepidoptera, Geometridae from the Azapa Valley, northern Chile

    Directory of Open Access Journals (Sweden)

    Héctor A. Vargas

    2011-12-01

    Full Text Available A new species of Eupithecia Curtis (Lepidoptera, Geometridae from the Azapa Valley, northern Chile. Male and female adults of a new species of Eupithecia Curtis from the Arica Province, Chile are described and illustrated. The species is compared with E. yubitzae Vargas & Parra, 2004, from the same locality, and E. galapagosata Landry & Rindge 1995, from the Galapagos Islands, Ecuador.

  1. A possible Plio-Pleistocene tsunami deposit, Hornitos, northern Chile

    Directory of Open Access Journals (Sweden)

    Adrian Hartley

    2001-07-01

    Full Text Available A section equivalent to the Pliocene La Portada Formation exposed in the coastal cliff at Hornitos, northern Chile, contains a ca. 7-10 m thick conglomerate bed. The bed occurs within a succession of shallow marine sandstones and has an erosional contact with underlying strata. The largest boulders of basement (5 m are angular to very angular and are set within a matrix of very poorly sorted fine to very coarse grained shell-rich sandstone. Also present are very well rounded granodiorite pebbles and shallow marine sandstone intraclasts (maximum 10 m. The clast size, erosional contact, associated facies and bed thickness suggests that the conglomerate bed is a shallow marine tsunami deposit. The angular clasts indicate limited transport and no marine reworking prior to deposition. They represent alluvial fan sediment incorporated into the bed during tsunami backflow. Intraclasts of shallow marine sandstone are thought to have been ripped up and included in the bed during the seaward passage of the tsunami across the shorefaceUn posible depósito de tsunami Plio-Pleistoceno, Hornitos, norte de Chile. Una sección equivalente a la Formación La Portada de edad pliocena, expuesta en el acantilado costero en el sector de Hornitos, norte del Chile, expone un estrato de conglomerados de ca. 7-10 m de potencia. El estrato ocurre dentro de una sucesión de areniscas marinas someras y tiene un contacto de erosión con los estratos infrayacentes. Los clastos mayores (5 m de basamento son angulares a muy angulares y se emplazan en una matriz arenisca de grano fino a muy grueso, pobre a muy pobremente seleccionada y con abundantes conchas. También están presentes clastos bien redondeados de granodiorita junto a intraclastos de areniscas marinas someras. El tamaño de los clastos, el contacto erosional, las facies asociadas y la potencia del estrato sugieren que el estrato de conglomerados es un depósito marino somero correspondiente a un tsunami. Los

  2. Craniofacial chronological microdifferentiation of human prehistoric populations of the Azapa valley, northern Chile Microdiferenciación cronológica craneofacial de poblaciones humanas prehistóricas del Valle de Azapa, norte de Chile

    Directory of Open Access Journals (Sweden)

    FRANCISCO ROTHHAMMER

    2002-03-01

    Full Text Available Archeological evidence suggest that the cultural developments occurred in the highlands around lake Titicaca in the Central Andes, exerted influence on the cultural elaborations of the human groups that peopled the valley of Azapa, close to the city of Arica, and the Pacific coast of northern Chile. In this communication we show by means of a distance analysis, that a craniofacial differentiation accompanied the process of cultural evolution in the valley. The biological influence of Tiwanaku is partially reflected in craniofacial morphology, providing preliminary evidence that cultural changes were associated to intermittent gene flow from the highlands, specially during the Alto Ramírez and San Miguel phasesLos desarrollos culturales ocurridos en el altiplano en el área circumtiticaca en los Andes centrales, ejercieron influencia sobre las elaboraciones culturales de los grupos humanos que poblaban el Valle de Azapa cercano a la ciudad de Arica y la costa del norte de Chile. En esta comunicación presentamos un análisis de distancias que demostró que una diferenciación craniofacial acompaño en el valle el proceso de evolución cultural. La influencia biológica de Tiwanaku se refleja parcialmente en la morfología craniofacial, proporcionando evidencia preliminar de que los cambios culturales en el valle se realizaron acompañados de flujo génico intermitente desde el altiplano, especialmente durante las fases Alto Ramírez y San Miguel

  3. Controls on continental strain partitioning above an oblique subduction zone, Northern Andes

    Science.gov (United States)

    Schütt, Jorina M.; Whipp, David M., Jr.

    2016-04-01

    Strain partitioning is a common process at obliquely convergent plate margins dividing oblique convergence into margin-normal slip on the plate-bounding fault and horizontal shearing on a strike-slip system parallel to the subduction margin. In subduction zones, strain partitioning in the upper continental plate is mainly controlled by the shear forces acting on the plate interface and the strength of the continental crust. The plate interface forces are influenced by the subducting plate dip angle and the obliquity angle between the normal to the plate margin and the convergence velocity vector, and the crustal strength of the continent is strongly affected by the presence or absence of a volcanic arc, with the presence of the volcanic arcs being common at steep subduction zones. Along the ˜7000 km western margin of South America the convergence obliquity, subduction dip angles and presence of a volcanic arc all vary, but strain partitioning is only observed along parts of it. This raises the questions, to what extent do subduction zone characteristics control strain partitioning in the overriding continental plate, and which factors have the largest influence? We address these questions using lithospheric-scale 3D numerical geodynamic experiments to investigate the influence of subduction dip angle, convergence obliquity, and weaknesses in the crust owing to the volcanic arc on strain partitioning behavior. We base the model design on the Northern Volcanic Zone of the Andes (5° N - 2° S), characterized by steep subduction (˜ 35°), a convergence obliquity between 31° -45° and extensive arc volcanism, and where strain partitioning is observed. The numerical modelling software (DOUAR) solves the Stokes flow and heat transfer equations for a viscous-plastic creeping flow to calculate velocity fields, thermal evolution, rock uplift and strain rates in a 1600 km x 1600 km box with depth 160 km. Subduction geometry and material properties are based on a

  4. Conductivity distribution beneath Lascar volcano (Northern Chile) and the Puna, inferred from magnetotelluric data

    Science.gov (United States)

    Díaz, Daniel; Brasse, Heinrich; Ticona, Faustino

    2012-03-01

    During two field campaigns in 2007 and 2010, long-period and broadband magnetotelluric measurements were conducted in the Central Andes of northern Chile and northwestern Argentina at a latitude of 23.7°S. The study area spans from the Precordillera over the active volcanic arc of the Western Cordillera until the western part of the Puna. A special focus was on Lascar, a subduction related stratovolcano with an historical activity characterized by fumarolic emissions and occasional sub-plinian eruptions, like the one occurred on 1993. The broadband instruments, covering a period range between T = 0.005 s and 1000 s, were installed in the proximities of Lascar volcano, while the long-period devices (T = 10 s-10,000 s) were installed on a profile slightly south of Lascar, crossing the Salar de Atacama basin, the volcanic arc and reaching the western border of the Puna. Remote reference and robust techniques were used for data processing. Induction vectors, phase tensor ellipses and strike direction of the conductivity distribution were calculated, showing some 3-D behavior for the Lascar sites at shallower depths, with induction vectors close to the edifice influenced partially by the topography. 3-D modeling and inversion revealed conductive anomalies beneath Lascar volcano, but also beneath the Puntas Negras volcanic chain. For the long-period transect, the behavior is closer to a 2-D case, with more stable strike direction coherent with induction vectors and phase tensor ellipses. The major result of 2-D inversion is a vast high-conductivity zone in the backarc crust, which seems to be the southern extension of a large highly conductive anomaly observed in prior studies beneath the Altiplano.

  5. {U}/{Pb} geochronology and significance of Late Permian ignimbrites in Northern Chile

    Science.gov (United States)

    Breitkreuz, Christoph; Van Schmus, W. R.

    1996-11-01

    {U}/{Pb} zircon ages of four ignimbrite samples from a Late Paleozoic volcaniclastic succession in northern Chile are presented. The 2 km thick succession consists of the Peine Fm. and the overlying Cas Fm., which crop out at the eastern margin of the Salar de Atacama near the village of Peine. One sample was collected from the oldest ignimbrite of the succession (Lower Member of the Peine Fm.); the other three samples were collected from the Middle Member of the Cas Fm. and its assumed equivalents. The {206Pb }/{238U } ages of all samples overlap within their analytical uncertainties, which results in a best estimate of 248 ± 3 Ma (Late Permian: Harland, 1990) for deposition of the entire succession. The age for the stratigraphically older sample is statistically indistinguishable from the other three samples, so that the depositional interval could have been less than 1 million years; maximum errors in the data allow that the Peine and Cas Fms. could have formed during a time span of 6 Ma. The data provide tight constraints on the age of these units, part of which formed in the Lanquir Caldera Complex. They also have implications for the stratigraphy and paleoclimatic models of the Southern Central Andes during the Late Permian. Although the zircon fractions analyzed here document Late Permian ages, they show varying amounts of inheritance of early Paleoproterozoic (to Late Archean?) zircons and also indicate the incorporation of ca. 2.5 Ga initial common lead to varying degrees. This and results from other studies in the area lead us to infer the existence, at least during the Paleozoic, of Precam-brian basement located below the Salar de Atacama area.

  6. Abandoned Beach Ridges in the Mejillones Peninsula, Northern Chile: Implications for Paleoseismology of Great Subduction Earthquakes.

    Science.gov (United States)

    del Río, I. A.; Gonzalez, G.; Antinao, J. L.; McDonald, E.; González-Carrasco, J. F.; Shrivastava, M. N.

    2015-12-01

    The Mejillones Peninsula, in northern Chile, shows a well-preserved set of beach ridges parallel to the present coast. These beach ridges can be observed up to 20 km inland and at 200 m above sea level. Previous dating performed in fossils extracted from the oldest beach ridges yielded ages of 400 ka (Victor et al., 2011). However, numerical ages for younger beach ridges have not been determined, therefore a complete time record is not available. InSar data show that the Mejillones Peninsula was uplifted several centimeters during the last two subduction earthquakes (Antofagasta Mw 8.1, 1995 earthquake and the Mw 7.7, 2007 Tocopilla earthquake) occurred in the area (Loveless et al., 2010). A permanent GPS station deployed by CALTECH (http://web.gps.caltech.edu/~jeff/andes/) in this peninsula has measured a coseismic uplift during the 2007 Tocopilla earthquake. This data suggest that the beach ridges were abandoned as a consequence of coseismic uplift during great subduction earthquakes and therefore they represent the long-term record of past earthquakes. In order to prove this hypothesis we excavated five trenches across the beach ridges. Our idea is to look for stratigraphic evidence of the abandonment mechanism and to collect samples for dating the beach ridges using the method of optically stimulated luminescence (OSL). The ages will be used to estimate long-term uplift rate and temporal variation of this rate. By confronting short-term uplift rate provided by GPS data with long-term rate we hope to know what it is the amount of the coseismic slip that remain in the geological record.

  7. Catastrophic debris avalanche deposit of Socompa volcano, northern Chile

    Science.gov (United States)

    Francis, P. W.; Gardeweg, M.; Ramirez, C. F.; Rothery, D. A.

    1985-01-01

    Between 10,000 and 500 yr ago the Socompa volcano in northern Chile experienced a catastrophic collapse of a 70 deg sector of the original cone, causing a debris avalanche that descended nearly 3000 m vertically and traveled more than 35 km from the volcano. The deposits cover some 490 sq km and have a minimum volume of 15 cu km. Parts of the original cone slumped in a nearly coherent form and are now preserved as large blocks more than 400 m high. The primary avalanche traveled northwestward over sloping ground before coming to rest transiently, forming a prominent marginal ridge, and then slid away northeastward to form a secondary flow, overriding much of the primary avalanche deposit. Abundant, prismatic, jointed dacite blocks within the debris avalanche deposit and a thin, fine-grained pumiceous deposit beneath it suggest that the collapse was triggered by magmatic activity and may have been accompanied by a violent lateral blast. Collapse was followed by eruption of pumiceous pyroclastic flows and extrusion of voluminous dacite domes.

  8. Monitoring the northern Chile megathrust with the Integrated Plate boundary Observatory Chile (IPOC)

    Science.gov (United States)

    Schurr, Bernd; Asch, Günter; Cailleau, Beatrice; Diaz, Guillermo Chong; Barrientos, Sergio; Vilotte, Jean-Pierre; Oncken, Onno

    2010-05-01

    The oceanic Nazca plate subducts beneath the continental South American plate by recurrent rupture of large segments of its interface. The resulting earthquakes are among the largest and most frequent on Earth. Along the Chilean and southern Peruvian margin, all sizeable segments have ruptured at least once in the past 150 years for which there exist historic and/or instrumental records. The one segment that is most mature for re-rupture stretches for more than 500 km along the northernmost Chilean coast between roughly -23° and -18° latitude. It last broke in 1877 in a magnitude ~8.5 earthquake, triggering a major Tsunami. From the historical record, it has been known to have a recurrence cycle of approximately 110 years. The adjoining segments to the south and north broke rather recently in 1995 and 2001 in M>8 earthquakes and an M 7.7 earthquake intruded into the southern part of the seismic gap in 2007 between Antofagasto and Tocopilla. This makes northern Chile a unique natural laboratory to observe a subduction megathrust at various stages of its seismic cycle. For that purpose, installation of long-term observatories started in 2006 in a close cooperation of the Universidad de Chile (Santiago, Chile), the Universidad Catolica del Norte (Antofagasta, Chile), the Institut de Physique du Globe de Paris (France), and the GFZ German research Centre for Geosciences (Germany). Currently we are operating 17 modern seismological stations equipped with STS-2 broadband seismometers and accelerometers (EPI sensor). At least two more stations will be installed in the near future. Continuous GPS, tilt, creep, climate and magnetotellurics measurements are complementing the seismological part. A majority of the sites provide data near real-time. We will present results of seismic monitoring including analysis of the 2007 M7.7 Tocopilla earthquake sequence that was recorded during the installation stage of the observatory. We relocated the mainshock and about a one

  9. River runoff and regional climate of a small glaciated catchment area in the Andes in southernmost Patagonia, Chile

    Science.gov (United States)

    Schneider, C.; Moritz, M.; Kilian, R.

    2003-04-01

    The river runoff from a small partly glaciated catchment area in southernmost Patagonian Andes in Chile is measured to analyse the influence of regional precipitation and climate dependent glacier ablation on runoff. The first data from March to September 2002 were compared to climate data recorded at an automatic weather station in the area. The poster presents the first detailed hydrometeorological investigation from this part of the Andes. The investigation area is located at 53°S in southernmost South America exactly east of the main divide of the mountain range of the Andes at 72.5°W. The catchment area of about 15 km2 comprises parts of the Gran Campo Nevado Ice Cap reaching up to 1500 m asl, and the outlet glacier Glaciar Lengua which ends at a proglacial lake at 100 m asl. The Gran Campo Nevado Ice Cap is the major ice mass between the Southern Patagonian Ice field in the north and the Strait of Magallan to the South. Climate in the area is characterised by whole-year round cool and super-humid conditions with a mean annual air temperature of 5,6°C at sea level and an annual precipitation sum of approximately 7,000 mm. The Río Lengua itself meets approximately 3.5 km downstreams from the proglacial lake into the fjord system of Canal Garjado which is a branch of Seno Skyring. A continuous hourly record of water levels in the river was obtained from two digital water depth sensors. Runoff was calibrated against river level by measuring runoff at different times with the tracer method of salt dilution and with velocity measurements employing a hydrometric vane. Mean runoff was computed to about 3 m3/s with peak flows exceeding 10 m3/s. Ablation on the glacier was estimated using the degree-day method with a degree-day factor that has been calibrated previously using data from a temporal energy balance weather station on Glacíar Lengua. The correlation between runoff and air temperature and precipitation returned significant correlation coefficients of rt

  10. Meteorological drivers of ablation processes on a cold glacier in the semi-arid Andes of Chile

    Directory of Open Access Journals (Sweden)

    S. MacDonell

    2013-09-01

    Full Text Available Meteorological and surface change measurements collected during a 2.5 yr period are used to calculate surface mass and energy balances at 5324 m a.s.l. on Guanaco Glacier, a cold-based glacier in the semi-arid Andes of Chile. Meteorological conditions are marked by extremely low vapour pressures (annual mean of 1.1 hPa, strong winds (annual mean of 10 m s−1, shortwave radiation receipt persistently close to the theoretical site maximum during cloud-free days (mean annual 295 W m−2; summer hourly maximum 1354 W m−2 and low precipitation rates (mean annual 45 mm w.e.. Snowfall occurs sporadically throughout the year and is related to frontal events in the winter and convective storms during the summer months. Net shortwave radiation provides the greatest source of energy to the glacier surface, and net longwave radiation dominates energy losses. The turbulent latent heat flux is always negative, which means that the surface is always losing mass via sublimation, which is the main form of ablation at the site. Sublimation rates are most strongly correlated with net shortwave radiation, incoming shortwave radiation, albedo and vapour pressure. Low glacier surface temperatures restrict melting for much of the period, however episodic melting occurs during the austral summer, when warm, humid, calm and high pressure conditions restrict sublimation and make more energy available for melting. Low accumulation (131 mm w.e. over the period and relatively high ablation (1435 mm w.e. means that mass change over the period was negative (−1304 mm w.e., which continued the negative trend recorded in the region over the last few decades.

  11. Lycaenid caterpillars (Lepidoptera, Lycaenidae eating flowers of Dalea pennellii var. chilensis (Fabaceae in the northern Chilean Andes

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    Héctor A. Vargas

    2014-09-01

    Full Text Available Lycaenid caterpillars (Lepidoptera, Lycaenidae eating flowers of Dalea pennellii var. chilensis (Fabaceae in the northern Chilean Andes. The shrub Dalea pennellii var. chilensis (Fabaceae is reported for the first time as a host plant for three Neotropical Polyommatini (Lepidoptera, Lycaenidae, Polyommatinae: Hemiargus ramon (Dognin, 1887, Leptotes trigemmatus (Butler, 1881 and Nabokovia faga (Dognin, 1895, based on two collections performed in the western slopes of the northern Chilean Andes in two consecutive summers. The relative abundance was always above 90% for N. faga while it was always less than 5% for H. ramon and L. trigemmatus. Furthermore, N. faga was not found on inflorescences of other native Fabaceae examined in the study site. This pattern suggests a close relationship between N. faga and D. pennellii var. chilensis, at least at a local scale.

  12. Geomorphological characterization of endorheic basins in northern Chile

    Science.gov (United States)

    Dorsaz, J.; Gironas, J. A.; Escauriaza, C. R.; Rinaldo, A.

    2011-12-01

    Quantitative geomorphology regroups a large number of interesting tools to characterize natural basins across scales. The application of these tools to several river basins allows the description and comparison of geomorphological properties at different spatial scales as oppose to more traditional descriptors that are typically applied at a single scale, meaning the catchment scale. Most of the recent research using these quantitative geomorphological tools has focused on open catchments and no specific attention has been given to endorheic basins, and the possibility of having particular features that distinguish them from exorheic catchments. The main objective of our study is to characterize endorheic basins and investigate whether these special geomorphological features can be identified. Because scaling invariance is a widely observed and relatively well quantified property of open basins, it provides a suitable tool to characterize differences between the geomorphology of closed and open basins. Our investigation focuses on three closed basins located in northern Chile which describe well the diversity in the geomorphology and geology of this arid region. Results show that endhoreic basins exhibit different slope-area and flow paths sinuosity regimes compared to those observed in open basins. These differences are in agreement with the particular self-similar behavior across spatial scales of the Euclidean length of subcatchments, as well as the Hack's law and Horton's ratios. These regimes imply different physical processes inside the channel network regardless of the basin area, and they seem to be related to the endorheic character of these basins. The analysis of the probability density functions of contributing areas and lengths to the lower region shows that the hypothesis of self-similarity can also be applied to closed basins. Theoretical expressions for these distributions were derived and validated by the data. Future research will focus on (1

  13. Testing for Changes in Crustal Velocity at the Tocopilla Earthquake, Northern Chile

    OpenAIRE

    Tom Eulenfeld [Richter; Günter Asch; Rainer Kind

    2011-01-01

    We use two different techniques to investigate the region between Antofagasta and Arica in northern Chile for crustal velocity changes. Data are taken from the 19 broadband stations of the IPOC project (Integrated Plate Boundary Observatory Chile) operating partly since 2006 by GFZ and Institut de Physique du Globe de Paris (IPGP). In the neighborhood of the seismic stations an M7.0 earthquake occurred near Tocopilla on 14 November 2007. Other studies have shown that in the course of such ear...

  14. The Bulimulidae (Mollusca: Pulmonata) from the Región de Atacama, northern Chile.

    Science.gov (United States)

    Araya, Juan Francisco

    2015-01-01

    The bulimulid genus Bostryx Troschel, 1847 is the most species-rich genus of land snails found in Chile, with the majority of its species found only in the northern part of the country, usually in arid coastal zones. This genus has been sparsely studied in Chile and there is little information on their distribution, diversity or ecology. Here, for the first time, a formal analysis of the diversity of bulimulids in the Región de Atacama, northern Chile, is reported. Of the seventeen species recorded for the area, most of them were efectively found in the field collections and one record was based on literature. Five taxa are described as new: Bostryx ancavilorum sp. nov., Bostryx breurei sp. nov., Bostryx calderaensis sp. nov., Bostryx ireneae sp. nov. and Bostryx valdovinosi sp. nov., and the known geographic distribution of seven species is extended. Results reveal that the Región de Atacama is the richest region in terrestrial snails in Chile, after the Juan Fernández Archipelago. All of the terrestrial molluscan species occurring in the area are endemic to Chile, most of them with restricted geographic distributions along the coastal zones, and none of them are currently protected by law. Further sampling in northern Chile will probably reveal more snail species to be discovered and described. PMID:26587346

  15. Atlantic Multidecadal Oscillation (AMO) forcing on the late Holocene Cauca paleolake dynamics, northern Andes of Colombia

    Science.gov (United States)

    Martínez, J. I.; Obrochta, S.; Yokoyama, Y.; Battarbee, R. W.

    2015-07-01

    The Atlantic Multidecadal Oscillation (AMO), is a major driving climate mechanism, in the eastern Caribbean Sea and the South Atlantic Ocean in relation to the dynamics of the South American Monsoon System (SAMS) for the late Holocene. Here we document the AMO signal in the San Nicolás-1 core of the Cauca paleolake (Santa Fé-Sopetrán Basin) in the northern Andes. Wavelet spectrum analysis of the gray scale of the San Nicolás-1 core provides evidence for a 70 yr AMO periodicity for the 3750 to 350 yr BP time interval, whose pattern is analogous to the one documented for the Cariaco Basin. This supports a possible correlation between enhanced precipitation and ENSO variability with a positive AMO phase during the 2000 to 1500 yr BP interval, and its forcing role on the Cauca ria lake deposits, which led to increased precipitation and to the transition from a igapo (black water) to a varzea (white water) environment ca. 3000 yr BP.

  16. Atlantic Multidecadal Oscillation (AMO forcing on the late Holocene Cauca paleolake dynamics, northern Andes of Colombia

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    J. I. Martínez

    2015-07-01

    Full Text Available The Atlantic Multidecadal Oscillation (AMO, is a major driving climate mechanism, in the eastern Caribbean Sea and the South Atlantic Ocean in relation to the dynamics of the South American Monsoon System (SAMS for the late Holocene. Here we document the AMO signal in the San Nicolás-1 core of the Cauca paleolake (Santa Fé–Sopetrán Basin in the northern Andes. Wavelet spectrum analysis of the gray scale of the San Nicolás-1 core provides evidence for a 70 yr AMO periodicity for the 3750 to 350 yr BP time interval, whose pattern is analogous to the one documented for the Cariaco Basin. This supports a possible correlation between enhanced precipitation and ENSO variability with a positive AMO phase during the 2000 to 1500 yr BP interval, and its forcing role on the Cauca ria lake deposits, which led to increased precipitation and to the transition from a igapo (black water to a varzea (white water environment ca. 3000 yr BP.

  17. Perennial stream discharge in the hyperarid Atacama Desert of northern Chile during the latest Pleistocene

    OpenAIRE

    Nester, Peter L.; Gayó, Eugenia; Latorre, Claudio; Jordan, Teresa E.; Blanco, Nicolás

    2007-01-01

    A large fraction of the vital groundwater in the Atacama Desert of northern Chile is likely composed of “fossil” or “ancient” reserves that receive little or no recharge in today's hyperarid climate. Here, we present evidence for latest Pleistocene perennial streamflow in canyons from the hyperarid core of the Atacama Desert in northern Chile. Fluvial terraces in the Pampa del Tamarugal (PdT) basin (21°S) contain widespread fossil wood, in situ roots, and well preserved leaf litter deposits i...

  18. The giant coastal landslides of Northern Chile: Tectonic and climate interactions on a classic convergent plate margin

    Science.gov (United States)

    Mather, Anne E.; Hartley, Adrian J.; Griffiths, James S.

    2014-02-01

    Documented for the first time are an extensive suite of late Neogene giant terrestrial coastal landslides along the classic convergent margin of western South America (18° to 24° south). These are remarkable in terms of their unusual abundance and atypical setting, such failures previously being linked with oceanic volcanic edifices or over-steepened glaciated coastlines. Located within the hyper-arid Coastal Cordillera of the Atacama Desert of Northern Chile we report the presence of more than 60 individual large-scale landslides with individual volumes up to 9 km3 developed over a horizontal coastline distance of some 650 km. These landslides were emplaced as a combination of rock avalanches and multiple rotational failures. The majority terminated directly into the Pacific - likely generating significant tsunami hazard to the Chilean and south Peruvian coastline in a region which is today considered to be part of a notorious seismic gap. The proliferation and scale of these Late Neogene giant landslides in this actively uplifting, hyperarid terrain suggests they are the main geomorphic agent for relief reduction, probably triggered by megathrust earthquakes and potentially providing a unique palaeoseismic archive. The temporal and spatial distribution of these giant landslides corresponds with a period of surface steepening of the forearc wedge in the Central Andes and south to north differential uplift associated with factors such as aseismic ridge subduction. The resulting surface gradient increases, combined with the persistent climatic aridity of the region, have served to limit effective relief-reducing geomorphic processes in this oversteepened terrain to large-scale landsliding. The phenomena documented here geospatially link previously recognised large-scale slope failures from the off-shore environment and higher altitude areas of the Andean forearc, suggesting that large-scale landsliding is capable of transferring sediment on a regional scale to the

  19. Active faulting in northern Chile: ramp stacking and lateral decoupling along a subduction plate boundary?

    Science.gov (United States)

    Armijo, Rolando; Thiele, Ricardo

    1990-04-01

    Two large features parallel to the coastline of northern Chile have long been suspected to be the sites of young or active deformation: (1) The 700-km long Coastal Scarp, with average height (above sea level) of about 1000 m; (2) The Atacama Fault zone, that stretches linearly for about 1100 km at an average distance of 30-50 km from the coastline. New field observations combined with extensive analysis of aerial photographs demonstrate that both the Coastal Scarp and the Atacama Fault are zones of Quaternary and current fault activity. Little-degraded surface breaks observed in the field indicate that these fault zones have recently generated large earthquakes ( M = 7-8). Normal fault offsets observed in marine terraces in the Coastal Scarp (at Mejillones Peninsula) require tectonic extension roughly orthogonal to the compressional plate boundary. Strike-slip offsets of drainage observed along the Salar del Carmen and Cerro Moreno faults (Atacama Fault system) imply left-lateral displacements nearly parallel to the plate boundary. The left-lateral movement observed along the Atacama Fault zone may be a local consequence of E-W extension along the Coastal Scarp. But if also found everywhere along strike, left-lateral decoupling along the Atacama Fault zone would be in contradiction with the right lateral component of Nazca-South America motion predicted by models of present plate kinematics. Clockwise rotation with left-lateral slicing of the Andean orogen south of the Arica bend is one way to resolve this contradiction. The Coastal Scarp and the Atacama Fault zone are the most prominent features with clear traces of activity within the leading edge of continental South America. The great length and parallelism of these features with the subduction zone suggest that they may interact with the subduction interface at depth. We interpret the Coastal Scarp to be a west-dipping normal fault or flexure and propose that it is located over an east-dipping ramp stack at

  20. Crustal contributions to arc magmatism in the Andes of Central Chile

    Science.gov (United States)

    Hildreth, W.; Moorbath, S.

    1988-01-01

    Fifteen andesite-dacite stratovolcanoes on the volcanic front of a single segment of the Andean arc show along-arc changes in isotopic and elemental ratios that demonstrate large crustal contributions to magma genesis. All 15 centers lie 90 km above the Benioff zone and 280??20 km from the trench axis. Rate and geometry of subduction and composition and age of subducted sediments and seafloor are nearly constant along the segment. Nonetheless, from S to N along the volcanic front (at 57.5% SiO2) K2O rises from 1.1 to 2.4 wt %, Ba from 300 to 600 ppm, and Ce from 25 to 50 ppm, whereas FeO*/MgO declines from >2.5 to 1.4. Ce/Yb and Hf/Lu triple northward, in part reflecting suppression of HREE enrichment by deep-crustal garnet. Rb, Cs, Th, and U contents all rise markedly from S to N, but Rb/Cs values double northward - opposite to prediction were the regional alkali enrichment controlled by sediment subduction. K/Rb drops steeply and scatters greatly within many (biotite-free) andesitic suites. Wide diversity in Zr/Hf, Zr/Rb, Ba/Ta, and Ba/La within and among neighboring suites (which lack zircon and alkali feldspar) largely reflects local variability of intracrustal (not slab or mantle) contributions. Pb-isotope data define a limited range that straddles the Stacey-Kramers line, is bracketed by values of local basement rocks, in part plots above the field of Nazca plate sediment, and shows no indication of a steep (mantle+sedimentary) Pb mixing trend. 87Sr/86Sr values rise northward from 0.7036 to 0.7057, and 143Nd/144Nd values drop from 0.5129 to 0.5125. A northward climb in basal elevation of volcanic-front edifices from 1350 m to 4500 m elevation coincides with a Bougueranomaly gradient from -95 to -295 mgal, interpreted to indicate thickening of the crust from 30-35 km to 50-60 km. Complementary to the thickening crust, the mantle wedge beneath the front thins northward from about 60 km to 30-40 km (as slab depth is constant). The thick northern crust contains

  1. Is tourism damaging ecosystems in the Andes? Current knowledge and an agenda for future research.

    Science.gov (United States)

    Barros, Agustina; Monz, Christopher; Pickering, Catherine

    2015-03-01

    Despite the popularity of tourism and recreation in the Andes in South America and the regions conservation value, there is limited research on the ecological impacts of these types of anthropogenic use. Using a systematic quantitative literature review method, we found 47 recreation ecology studies from the Andes, 25 of which used an experimental design. Most of these were from the Southern Andes in Argentina (13 studies) or Chile (eight studies) with only four studies from the Northern Andes. These studies documented a range of impacts on vegetation, birds and mammals; including changes in plant species richness, composition and vegetation cover and the tolerance of wildlife of visitor use. There was little research on the impacts of visitors on soils and aquatic systems and for some ecoregions in the Andes. We identify research priorities across the region that will enhance management strategies to minimise visitor impacts in Andean ecosystems. PMID:25201299

  2. Photosynthetic performance of Colobanthus quitensis (Kunth Bartl. (Caryophyllaceae in a high-elevation site of the Andes of central Chile Desempeño fotosintético de Colobanthus quitensis (Kunth Bartl. (Caryophyllaceae en los Andes de Chile central

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    M. ANGÉLICA CASANOVA-KATNY

    2006-03-01

    Full Text Available Photosynthesis of Colobanthus quitensis and mesoclimatic conditions of air temperature and light intensity during the growing season were investigated at 2,650 m in the central Chilean Andes. On three typical days of the growing period (January, March and May, CO2 exchange and chlorophyll fluorescence were measured. In addition, a series of fluorescence response curves with increasing light intensity at different temperatures were performed to estimate the propensity of Andean C. quitensis populations to be photoinhibited. Net Photosynthesis (Pn was low (ca. 2.0 mmol CO2 m-2s-1 during the morning and noon in days with high photosynthetic active radiation (PAR, above 1,800 mmol photons m-2s-1. Pn increased in the afternoon (3.5-4.8 mmol CO2 m-2s-1 when PAR decreased to ca. 1,400 mmol photons m-2s-1 and leaf temperature were ca. 20 °C. Fv/Fm in the diurnal periods was between 0.7-0.75 without evidence of photoinhibition. Leaves at 15 and 22 °C exhibited a slow decrease of F PSII with the increase in actinic light intensity, although the fraction of reaction centers open (expressed by qP remained higher at 22 °C. NPQ was saturated at light intensities close to 500 mmol photons m-2s-1 in leaves at 22 °C and at higher intensities at 15 °C, suggesting that NPQ could be a mechanism of energy dissipation at high light intensity and high leaf temperature in the field. Our results indicated that C. quitensis is not photodamaged during the diurnal cycle and that the low Pn registered during some diurnal periods are likely to be related with photorespiration, which has been suggested as an efficient protective mechanism for photoinhibition in alpine plants. Our results are also compared with the photosynthetic performance of C. quitensis populations from the maritime AntarcticSe estudió la fotosíntesis de Colobanthus quitensis y las condiciones mesoclimáticas de temperatura del aire e intensidad lumínica a 2.650 m en los Andes de Chile central. Se

  3. Gender relations and masculinity in northern Chile mining areas: ethnography in schoperías

    OpenAIRE

    Barrientos Delgado, Jaime; Salinas Meruane, Paulina; Rojas Varas, Pablo; Meza Opazo, Patricio

    2013-01-01

    This paper deals with an ethnography aimed at describing and ­understanding the gendered organization of schopería life and masculinity in northern Chile. Schoperías are characterized physically and socially and the effects these ­premises have on gender relations and masculinity assigned to them by waitresses and clients are studied. Schoperías are beer halls, mainly for men, ­served by women, located in cities near copper mines in Chile. They are strongly ­gendered and classed places. Schop...

  4. Assessing the performance of hybrid CSP+PV plants in northern Chile

    Science.gov (United States)

    Starke, Allan; Cardemil, José M.; Escobar, Rodrigo; Colle, Sergio

    2016-05-01

    The electricity systems in Chile are characterized by a variable hourly demand in the central grid and an almost constant demand in the northern grid, which require different operation strategies for solar power plants depending on their location. Hybridizing a CSP plant with a PV plant can increase the whole plant capacity factor by allowing thermal energy to be stored while the PV plant is in production and thus help to achieve a fully dispatchable solar electricity production system. A thermal and economic analysis of hybrid CSP+PV plants is conducted considering a range of plant capacities based on a parabolic trough plant with the addition of a PV plant for the environmental conditions of Crucero in Northern Chile, which is a hotspot for solar energy development in the country. The study considers a parametric analysis and optimization of the storage and power block sizes for the CSP plant in terms of the levelized cost of energy (LCOE) for varying PV plant nominal capacity. The annual production of the plants are calculated by using the Transient System Simulation program (TRNSYS), which uses a new component library developed for that purpose. The results show good agreement with other software packages as well as with actual data from currently operating CSP plants. The adopted approach helps the proper assessment of the integration of different technologies, since it uses the well-kwon modular structure of the TRNSYS. Regarding the potential for the hybrid solar-solar plants in the Atacama Desert, the high level of irradiation available in Chile can provide a competitive electricity cost, allowing to investors the access to PPA contracts with mining companies in northern Chile. Additionally, the optimization analysis shows that the northern regions of Chile present an outstanding potential for the deployment of such projects.

  5. Neotectónica de los Andes entre 1°N y 47°S (Ecuador, Bolivia y Chile: una revisión

    Directory of Open Access Journals (Sweden)

    A. Lavenu

    2006-12-01

    Full Text Available En los Andes, el estudio del estado de deformación instantánea pleistocena permite reconocer diferentes tipos de comportamientos de la placa continental de Sudamérica a lo largo del margen activo. En Ecuador, el bloque costero está empujado hacia el norte. La costa es afectada por una extensión de dirección N-S, resultado del levantamiento del borde del continente por la subducción de la dorsal asísmica de Carnegie. Por otra parte, la cadena principal sufre una deformación compresiva de dirección E-W. Los altos Andes de Bolivia han sido afectados por una deformación pleistocena extensional de dirección N-S. En el centro y sur de Chile, se observa una partición de la deformación: la zona de antearco ha sido afectada por una compresión N-S y la zona de intraarco por transpresión de dirección NE-SW.

  6. Late cenozoic tectonic and geomorphic evolution of the Patagonian Andes between 42oS and 52oS, southern Chile assessed using fission-track thermochronology

    International Nuclear Information System (INIS)

    Fission-track (FT) analysis has been applied in the Patagonian Andes of southern Chile to assess the late Cenozoic geomorphic and tectonic response of the overriding plate to subduction of the Chile rise active oceanic spreading centre (Thomson et al., 2001). The timing and nature of tectonic uplift and denudation along the southern parts of the major transpression intra-arc Liquine-Ofqui fault (LOF) system have also been investigated (Thomson, 2001, submitted). Results from 130 FT ages (72 zircon and 58 apatite ages) and 39 apatite track length measurements reveal initiation of rapid cooling and denudation at ca. 30 Ma at the western margin of southern continental South America. This was followed by a ca. 200km eastward migration of the locus of maximum denudation to the position of the present day topographic divide between ca. 30 Ma and ca. 12 to 10 Ma. East of the Andean divide less than 3 km of denudation has occurred since the Late Cretaceous. Enhanced denudation is interpreted to be the result of increased tectonic uplift driven by a large increase in convergence rates at ca. 28 to 26 Ma that triggered orographically enhanced precipitation on the west-side of the Patagonian Andes allowing increased erosion by fluvial incision and mass transport processes. The eastward migration of the locus of maximum denudation can be related to either coeval eastward migration of the retro-arc deformation front, the effects of subduction erosion in the overriding plate at the Peru-Chile trench or shallowing of the angle of subduction. Away from the influence of the LOF the process of spreading centre subduction and collision itself coincides with an overall slow-down in denudation rates in the overriding plate most likely caused by a major reduction in the main tectonic force driving tectonic uplift in the upper plate to subduction. In contrast to the Andes south of ca. 46oS, increased cooling and denudation related to transpression induced rock uplift and erosion along

  7. Chemical Mineralogy, Geochemical Characterization and Petrography of the Cambumbia Stock, Northern Andes, South America, Colombia

    Science.gov (United States)

    Rojas Lequerica, Salvador; María Jaramillo Mejía, José; Concha Perdomo, Ana Elena; Jimenez Quintero, Camilo

    2013-04-01

    The Cambumbia Stock is located on the western flank of the Central Cordillera of the northern Andes, South America. The goals of this study were to characterize the mineral chemistry, the geochemical composition and the petrography of the Cambumbia igneous body and to establish its petrogenesis. We collected 41 samples, selected 28 for thin section petrographic analysis, 14 for whole rock elementary chemical determination by ICP-MS and 4 for chemical mineralogy by LA-ICP(JEOL JXA-8200). Petrographically the samples were classified as 30 % hornblende-gabbro, 30% pyroxene-gabbros, 10% diorites, 10% olivine-gabbro, 7% gabbronorites, 7% tonalities and 3% norite, 3% wehrlite, the rock varies from medium to coarse hipidiomorfic and holocristaline texture, with local microporfiritic texture. Spot elemental chemical analysis of the some minerals in 4 samples show the range of the major elemental composition is plagioclase (labradorite), clinopyroxene (augite), horblende (magnesiohornblende), olivine (fayalite())Chemical mineralogy shows the variety of minerals in this rock, essential minerals correspond to bytownite, augite, magnesio-honblende, fallaite and titanite. We conclude base on the SiO2 Vs Total Alkalis graph that the samples correspond to the sub-alkaline series with low K content, mainly in the calc-alkaline series. By using the SiO2 vs TiO2, Th/Yb vs Ta/Yb and Zr/117-Th-Nb/16 diagrams it was determined that these rocks were generated in two geotectonic environments: one type MOR (extension) and other island arc (subduction, compression). Recently, a U/Pb age was obtained by the Universidad de Caldas in zircon in 2009 (not published data), yielded an age of 233.41 ± 3.4 Ma (Carnian - Upper Triassic). Petrographic geochemical and geochronology comparisons between the rocks of Cambumbia Stock and Diorite and Gabbro El Pueblito (located about 25 km to the north-west) and with U/Pb age 231 ± 8 may postulate a possible genetic link between them. These ages are

  8. First remarks on the nesting biology of Hypodynerus andeus (Packard) (Hymenoptera, Vespidae, Eumeninae) in the Azapa valley, northern Chile

    OpenAIRE

    Felipe Méndez-Abarca; Enrique A. Mundaca; Héctor A. Vargas

    2012-01-01

    First remarks on the nesting biology of Hypodynerus andeus (Packard) (Hymenoptera, Vespidae, Eumeninae) in the Azapa valley, northern Chile. Some aspects about the nesting biology of the potter wasp Hypodynerus andeus (Packard, 1869) are reported for the first time. Observations were carried out at the Azapa valley, coastal desert of northern Chile. A total of sixty nests were collected and examined, each composed by 1-14 cells, most of them found attached to concrete lamp posts. The only pre...

  9. Proximity to mining industry and respiratory diseases in children in a community in Northern Chile: A cross-sectional study

    OpenAIRE

    Herrera, Ronald; Radon, Katja; von Ehrenstein, Ondine S.; Cifuentes, Stella; Muñoz, Daniel Moraga; Berger, Ursula

    2016-01-01

    Background In a community in northern Chile, explosive procedures are used by two local industrial mines (gold, copper). We hypothesized that the prevalence of asthma and rhinoconjunctivitis in the community may be associated with air pollution emissions generated by the mines. Methods A cross-sectional study of 288 children (aged 6–15 years) was conducted in a community in northern Chile using a validated questionnaire in 2009. The proximity between each child’s place of residence and the mi...

  10. The shallow-water chitons (Mollusca, Polyplacophora of Caldera, Region of Atacama, northern Chile

    Directory of Open Access Journals (Sweden)

    Juan Francisco Araya

    2015-03-01

    Full Text Available The Molluscan species of the northern littoral of Chile have been sparsely studied. This work reviews for the first time the diversity of polyplacophoran molluscs around the port of Caldera, in the Region of Atacama (26°45’49”S; 70°45’17”W to 27°20’23”S; 70°56’46”W, northern Chile. Eleven species were found in this study: Acanthopleura echinata (Barnes, 1824; Callistochiton pulchellus (Gray, 1828; Calloplax vivipara (Plate, 1899, Chaetopleura peruviana (Lamarck, 1819; Chiton cumingsii Frembly, 1827; Chiton granosus Frembly, 1827; Chiton magnificus Deshayes, 1827; Enoplochiton niger (Barnes, 1824, Radsia barnesii (Gray, 1828, Tonicia atrata (G. B. Sowerby II, 1840 and Tonicia chilensis (Frembly, 1827. All of the species occurring in the area have distributions in the southeastern Pacific Ocean, from Ecuador to central Chile, and three of them are species endemic to the Chilean coasts (Calloplax vivipara, Radsia barnesii, and Tonicia atrata. This diversity of species is comparable to that of better surveyed faunas of central and southern Chile or Patagonia. Of the eleven species recorded, the geographic distribution records for Callistochiton pulchellus, Radsia barnesii and Tonicia atrata are extended, and Calloplax vivipara is found alive again after 40 years, filling a gap in its known distribution. Illustrations of living specimens in their habitat, distribution records and a taxonomic key for all the studied taxa are also provided.

  11. Diversity of Bacteroidetes in high altitude saline evaporitic basins in northern Chile

    OpenAIRE

    Dorador, Cristina; Meneses, D.; Urtuvia, V.; Demergasso, C.; Vila, I; Witzel, K.-P.; Imhoff, Johannes F.

    2009-01-01

    The phylum Bacteroidetes represents one of the most abundant bacterial groups of marine and freshwater bacterioplankton. We investigated the diversity of Bacteroidetes in water and sediment samples from three evaporitic basins located in the highlands of northern Chile. We used both 16S rRNA gene clone libraries created with targeted Bacteroidetes-specific primers and separation of specifically amplified gene fragments by denaturing gradient gel electrophoresis (DGGE). DGGE analysis revealed ...

  12. Paleomagnetism and tectonics of the southern Atacama Desert (25-28 degrees S), northern Chile

    OpenAIRE

    Arriagada, C.; Roperch, Pierrick; Mpodozis, C.; Fernandez, R

    2006-01-01

    We report paleomagnetic results for 131 sites from the modern forearc of northern Chile (25 degrees S and 28 degrees S). Remanent magnetization in volcanic and intrusive rocks is mostly primary, while a secondary magnetization is observed in sedimentary rocks. Comparison of locality-mean directions with expected paleomagnetic directions indicates vertical axis rotations from -7.3 degrees +/- 21.6 degrees counterclockwise to 52.7 degrees +/- 17 degrees clockwise. Jurassic to Early Cretaceous r...

  13. Polygenetic development and paleoenvironmental implications of a Pleistocene calcrete at Tongoy, central northern Chile.

    OpenAIRE

    M. Pfeiffer; J. Le Roux; H. Kemnitz

    2011-01-01

    The Norte Chico Region, in central northern Chile, is a particularly sensitive area to Quaternary climate changes because of its extreme climatic gradients. However, very little has been done to determine the late Pleistocene climatic conditions of the area. Calcretes are known to be important repositories of information on past ecosystems and environments. In the Tongoy paleobay, a series of four marine beach terraces have developed over a Mio-Pliocene calcareous formation since MIS 11 to th...

  14. Impact of Empire Expansion on Household Diet: The Inka in Northern Chile's Atacama Desert

    OpenAIRE

    Vinton, Sheila Dorsey; Perry, Linda; Reinhard, Karl J.; Santoro, Calogero M.; Teixeira-Santos, Isabel

    2009-01-01

    The impact of expanding civilization on the health of American indigenous societies has long been studied. Most studies have focused on infections and malnutrition that occurred when less complex societies were incorporated into more complex civilizations. The details of dietary change, however, have rarely been explored. Using the analysis of starch residues recovered from coprolites, here we evaluate the dietary adaptations of indigenous farmers in northern Chile's Atacama Desert during the...

  15. Dimorphinites (Ammonoidea, Jurassic, Upper Bajocian) in the Precordillera of Northern Chile

    OpenAIRE

    Fernández López, Sixto Rafael; Chong Díaz, Guillermo B.

    2011-01-01

    A new upper Bajocian ammonite assemblage containing the morphoceratids Dimorphinites dimorphus (d’Orbigny) and Vigoriceras defrancei (d’Orbigny) is reported from the circum-Pacific area. These ammonites were found at the top of the Torcazas Formation, in the Quebrada San Pedro area, Precordillera of northern Chile. Taphonomic, systematic, and paleobiogeographic data confirm these dimorphs were part of indigenous populations within the Tarapaca Basin, belonging to the same demic bi...

  16. Recent temperature trends in the South Central Andes reconstructed from sedimentary chrysophyte stomatocysts in Laguna Escondida (1742 m a.s.l., 38°28 S, Chile)

    Science.gov (United States)

    De Jong, R.; Schneider, T.; Hernández-Almeida, I.; Grosjean, M.

    2016-02-01

    In this study we present a quantitative, high resolution reconstruction of past austral winter length in the Chilean Andes at 38°S from AD 1920 to 2009. For Laguna Escondida, a nearly pristine lake situated on the flanks of the Andes at 1740 m above sea level, past variability in the duration of the winter season (Days T4 °C) was reconstructed. Because high elevation meteorological stations are absent in this region, the reconstruction provides novel insights into recent temperature trends in the central-southern Andes. As a cold-season temperature proxy, we used chrysophyte stomatocysts. This novel proxy for cold season temperature was so far applied successfully in the European Alps and Pyrenees but has not yet been tested in the Southern Hemisphere. The reconstruction in this study was based on a newly developed Transfer Function to estimate Days T4 °C (number of consecutive days with surface water temperatures at or below 4 °C) from sedimentary stomatocyst assemblages (R2boot = 0.8, RMSEPboot = 28.7 days (= half the standard deviation)). To develop a high quality TF model, sediment traps and thermistors were placed in thirty remote lakes along an altitude gradient (420-2040 m a.s.l.). Complete materials and data were collected in 24 lakes after one year. Detailed statistical analyses indicate that modern stomatocysts primarily respond to the length of the cold season. The TF model was then applied to the sedimentary stomatocysts from a 210Pb-dated short core of L. Escondida. Comparison to independent reanalysis data showed that reconstructed changes in Days T4°C provides detailed information on winter-spring temperature variability since AD 1920. The reconstruction shows that recent warming (onset in AD 1980) in the southern Chilean Andes was not exceptional in the context of the past century. This is in strong contrast to studies from the Northern Hemisphere. The finding is also in contrast to the cooling temperature trends which were detected using

  17. The Iconography of Painted Ceramics from the Northern Andes Title: La iconografía de la cerámica pintada del norte de los Andes

    OpenAIRE

    Felipe Cárdenas-Arroyo

    1998-01-01

    Felipe Cárdenas-Arroyo, arqueólogo colombiano de la Universidad de Los Andes en Bogotá, erudito de CASVA, especialista en momificación pre-hispánica de huesos humanos.Abstract: Felipe Cárdenas-Arroyo, Colombian archaeologist from the University of Los Andes in Bogotá, CASVA scholar, specialist in pre-Hispanic mummification and human bone.

  18. Chile.

    Science.gov (United States)

    1992-05-01

    The background notes on Chile provide a statistical summary of the population, geography, government, and the economy, and more descriptive text on the history, population, government, economy, defense, and foreign relations. In brief, Chile has 13.3 million Spanish Indian (Mestizos), European, and Indian inhabitants and an annual growth rate of 1.6%. 96% are literate. Infant mortality is 18/1000. 34% of the population are involved in industry and commerce, 30% in services, 19% in agriculture and forestry and fishing, 7% in construction, and 2% in mining. The major city is Santiago. The government, which gained independence in 1810, is a republic with executive, legislative, and judicial branches. There are 12 regions. There are 6 major political parties. Suffrage is universal at 18 years. Gross domestic product (GDP) is $29.2 billion. The annual growth rate is 5% and inflation is 19%. Copper, timber, fish, iron ore, nitrates, precious metals, and molybdenum are its natural resources. Agricultural products are 9% of GDP and include wheat, potatoes, corn, sugar beets, onions, beans, fruits, and livestock. Industry is 21% of GDP and includes mineral refining, metal manufacturing, food and fish processing, paper and wood products, and finished textiles. $8.3 billion is the value of exports and $7 billion of imports. Export markets are in Japan, the US, Germany, Brazil, and the United Kingdom. Chile received $3.5 billion in economic aid between 1949-85, but little in recent years. 83% live in urban centers, principally around Santiago. Congressional representation is made on the basis of elections by a unique binomial majority system. Principal government officials are identified. Chile has a diversified free market economy and is almost self-sufficient in food production. The US is a primary trading partner. 49% of Chile's exports are minerals. Chile maintains diplomatic relations with 70 countries, however, relations are strained with Argentina and Bolivia. Relations

  19. Tectonic control on rock uplift, exhumation, and topography above an oceanic ridge collision: Southern Patagonian Andes (47°S), Chile

    Science.gov (United States)

    Georgieva, Viktoria; Melnick, Daniel; Schildgen, Taylor F.; Ehlers, Todd A.; Lagabrielle, Yves; Enkelmann, Eva; Strecker, Manfred R.

    2016-06-01

    The subduction of bathymetric anomalies at convergent margins can profoundly affect subduction dynamics, magmatism, and the structural and geomorphic evolution of the overriding plate. The Northern Patagonian Icefield (NPI) is located east of the Chile Triple Junction at ~47°S, where the Chile Rise spreading center collides with South America. This region is characterized by an abrupt increase in summit elevations and relief that has been controversially debated in the context of geodynamic versus glacial erosion effects on topography. Here we present geomorphic, thermochronological, and structural data that document neotectonic activity along hitherto unrecognized faults along the flanks of the NPI. New apatite (U-Th)/He bedrock cooling ages suggest faulting since 2-3 Ma. We infer the northward translation of an ~140 km long fore-arc sliver -- the NPI block -- results from enhanced partitioning of oblique plate convergence due to the closely spaced collision of three successive segments of the Chile Rise. In this model, greater uplift occurs in the hanging wall of the Exploradores thrust at the northern leading edge of the NPI block, whereas the Cachet and Liquiñe-Ofqui dextral faults decouple the NPI block along its eastern and western flanks, respectively. Localized extension possibly occurs at its southern trailing edge along normal faults associated with margin-parallel extension, tectonic subsidence, and lower elevations along the Andean crest line. Our neotectonic model provides a novel explanation for the abrupt topographic variations inland of the Chile Triple Junction and emphasizes the fundamental effects of local tectonics on exhumation and topographic patterns in this glaciated landscape.

  20. Reconstructing glacier mass balances in the Central Andes of Chile and Argentina using local and regional hydro-climatic data

    Directory of Open Access Journals (Sweden)

    M. H. Masiokas

    2015-09-01

    Full Text Available Despite the great number and variety of glaciers in southern South America, in situ glacier mass balance records are extremely scarce and glacier–climate relationships are still poorly understood in this region. Here we use the longest (> 35 years and most complete in situ mass balance record, available for glaciar Echaurren Norte in the Andes at ~34° S, to develop a minimal glacier surface mass balance model that relies on nearby monthly precipitation and air temperature data as forcing. This basic model is able to explain 78 % of the variance in the annual glacier mass balance record over the 1978–2013 calibration period. An attribution assessment indicates that precipitation variability constitutes the most important forcing modulating annual glacier mass balances at this site. A regionally-averaged series of mean annual streamflow records from both sides of the Andes is then used to estimate, through simple linear regression, this glacier's annual mass balance variations since 1909. The reconstruction model captures 68 % of the observed glacier mass balance variability and shows three periods of sustained positive mass balances embedded in an overall negative trend totaling almost −42 m w.eq. over the past 105 years. The three periods of sustained positive mass balances (centered in the 1920s–1930s, in the 1980s and in the first decade of the 21st century coincide with several documented glacier advances in this region. Similar trends observed in other shorter glacier mass balance series suggest the glaciar Echaurren Norte reconstruction is representative of larger-scale conditions and could be useful for more detailed glaciological, hydrological and climatological assessments in this portion of the Andes.

  1. Use of time series of optical and SAR images in the estimation of snow cover for the optimization of water use in the Andes of Argentina and Chile

    Science.gov (United States)

    Salinas de Salmuni, Graciela; Cabezas Cartes, Ricardo; Menicocci, Felix

    2014-05-01

    This paper describes the progress in the bilateral cooperation project between academic and water resources management institutions from the Andes region of Argentina and Chile. The study zone is located in fragile ecosystems and mountain areas of the Andes (limit zone between the Province of San Juan, Argentina, and the IV Region of Coquimbo, Chile), with arid climate, where snow precipitates in the headwaters of watershed feed the rivers of the region by melting, which are the only source of water for human use, productive and energetic activities, as well as the native flora and fauna. CONAE, the Argentine Space Agency, participates in the Project through the provision of satellite data to the users and by this it contributes to ensuring the continuity of the results of the project. Also, it provides training in digital image processing. The project also includes the participation of water resource management institutions like Secretaria de Recursos Hidricos of Argentina and the Centro de Información de Recursos Naturales de Chile (CIREN), and of academic institution like the University of San Juan (Argentina) and University of La Serena (Chile). These institutions benefit from the incorporation of new methodologies advanced digital image processing and training of staff (researcher, lecturers, PhD Students and technical). Objectives: 1-Improve water distribution incorporating space technology for application in the prediction models of the stream flow. 2- Conduct an inventory of glaciers as well as studies in selected watersheds in the Andean region, aiming to know the water resource, its availability and potential risks to communities in the region. 3. Contribute to vulnerability studies in biodiversity Andean watersheds. Results: For estimation Snow cover Area, the MODIS images are appropriate due their high temporal resolution and allows for monitoring large areas (greater than 10 km) The proposed methodology (Use of snow index, NSDI) is appropriate for

  2. Parasite loads and altitudinal distribution of Liolaemus lizards in the central Chilean Andes Cargas parasitarias y distribución de lagartijas Liolaemus en los Andes de Chile central

    Directory of Open Access Journals (Sweden)

    JOHN H. CAROTHERS

    2001-09-01

    Full Text Available This study compared the distributions of ten species of Liolaemus lizards in the central Chilean Andes to the distributions of four types of parasites: malaria-causing Plasmodium, gut nematodes, ticks, and mites. We wanted to see if parasite numbers might be a factor in determining distributional limits of the lizards. We found that there was no evidence of malarial infestation of the lizards, that ticks were almost absent, that more often than not mite numbers decreased at the distributional limits of the lizards, and that gut nematodes confined to the herbivorous lizards in our sample may well be beneficial rather than detrimental. Rather than parasitism, other biotic interactions (e.g., predation or competition are more likely candidates as factors influencing lizard elevational distributions, as are abiotic characteristics such as microhabitat availabilities and thermal factorsEste estudio compara las distribuciones de diez especies de lagartijas Liolaemus en los Andes de Chile central, con las distribuciones de cuatro tipos de parásitos: Plasmodium causantes de malaria, nemátodos intestinales, garrapatas y ácaros. Quisimos verificar si los números de parásitos pudieran ser un factor determinante de los límites de distribución de las lagartijas. Encontramos que no había evidencia de infestación por malaria en las lagartijas; que las garrapatas estaban casi ausentes; que los números de ácaros más a menudo decrecían que aumentaban en los límites distribucionales de las lagartijas; y que los nemátodos intestinales confinados a las lagartijas herbívoras en nuestra muestra bien podían ser beneficiosos antes que dañinos. Más bien que parasitismo, otras interacciones bióticas (e.g., depredación o competencia son candidatos más probables como factores que influyen las distribuciones altitudinales de las lagartijas, además de características abióticas tales como la disponibilidad de microhábitats y los factores térmicos

  3. Geothermal Potential Evaluation for Northern Chile and Suggestions for New Energy Plans

    Directory of Open Access Journals (Sweden)

    Monia Procesi

    2014-08-01

    Full Text Available Chile is a country rich in natural resources, and it is the world’s largest producer and exporter of copper. Mining is the main industry and is an essential part of the Chilean economy, but the country has limited indigenous fossil fuels—over 90% of the country’s fossil fuels must be imported. The electricity market in Chile comprises two main independent systems: the Northern Interconnected Power Grid (SING and the Central Interconnected Power Grid (SIC. Currently, the primary Chilean energy source is imported fossil fuels, whereas hydropower represents the main indigenous source. Other renewables such as wind, solar, biomass and geothermics are as yet poorly developed. Specifically, geothermal energy has not been exploited in Chile, but among all renewables it has the greatest potential. The transition from thermal power plants to renewable energy power plants is an important target for the Chilean Government in order to reduce dependence on imported fossil fuels. In this framework, the proposed study presents an evaluation of the geothermal potential for northern Chile in terms of power generation. The El Tatio, Surire, Puchuldiza, Orriputunco-Olca and Apacheta geothermal fields are considered for the analysis. The estimated electrical power is approximately 1300 MWe, and the energy supply is 10,200 GWh/year. This means that more than 30% of the SING energy could be provided from geothermal energy, reducing the dependence on imported fossil fuels, saving 8 Mton/year of CO2 and supplying the mining industry, which is Chile’s primary energy user.

  4. Depositación atmosférica de nitrógeno en un transecto valle longitudinal-cordillera de Los Andes, centro-sur de Chile Atmospheric deposition of nitrogen in a transect from the Central Valley to Cordillera de Los Andes, south-central Chile

    Directory of Open Access Journals (Sweden)

    CARLOS E. OYARZÚN

    2002-03-01

    Full Text Available El aumento de las actividades agrícolas y ganaderas en el centro-sur de Chile puede producir elevadas emisiones de nitrógeno hacia la atmósfera (mayormente NH3. El amoniaco es transportado por corrientes de aire y depositado en el suelo y vegetación. El presente estudio evalúa la depositación atmosférica de compuestos nitrogenados (NO3- y NH4+ en la química de las precipitaciones en un transecto altitudinal de 66 km, desde los alrededores de la ciudad de Osorno (40º 35' S, 72º 57' O, 55 m de altitud hasta la cordillera de Los Andes, Parque Nacional Puyehue (40º 46' S, 72º 11' O, 1.120 m de altitud. En siete sitios, durante el período anual junio-1999 hasta mayo-2000, se registró la precipitación y mensualmente se colectaron muestras de agua para determinar: pH, conductividad y las concentraciones de NO3- y NH4+. La precipitación anual se incrementó desde 1.103 mm en la zona de Osorno hasta 6.799 mm en el sector Antillanca, Parque Nacional Puyehue. Los valores promedio anual del pH registraron escasa variación desde 6,3 en el valle central hasta 5,8 en la cordillera de Los Andes. La conductividad presentó los máximos valores en la proximidad de Osorno (22,9 myS cm-1 para descender a través del transecto en zonas intermedias y alcanzar en la Cordillera de los Andes un valor de 11,3 myS cm-1. Las concentraciones promedio de NO3-Nen la lluvia fluctuaron entre 52,3 myg L-1 en la zona agrícola-ganadera y 6,9 myg L-1 en los bosques del Parque Nacional Puyehue. Las concentraciones de NH4-N variaron entre 699,4 myg L-1 en el sector de Osorno y 37,8 myL-1 en la cordillera de Los Andes. Los valores de N-inorgánico poseen una marcada tendencia estacional en el sector agrícola, con valores máximos en primavera-verano y los mínimos en invierno. Las tasas anuales de depositación atmosférica de NO3-N fluctuaron entre 0,53 y 0,57 kg ha-1 año-1 y las de NH4-N fueron entre 6,4 y 2,8 kg ha-1 año-1 para los sitios agrícola-ganaderos de

  5. Segmentation of Seismicity in the Mejillones Region, Northern Chile

    Science.gov (United States)

    Kummerow, Joern; Bloch, Wasja; Salazar, Pablo; Wigger, Peter; Shapiro, Serge A.

    2016-04-01

    The Mejillones Peninsula constitutes a widely accepted seismic barrier which separates two major segments of the Andean subduction zone. There is no evidence that past earthquake ruptures have traversed the barrier. We recently deployed a dense seismic monitoring system on Mejillones to study the local structure and seismicity distribution in greater detail. Between June 2013 and October 2015 we detected about 3000 micro seismic events with magnitudes down to Ml = 0.5 and determined P- and S- arrival times. Precise event location was performed using a regionally updated velocity model and waveform similarity- based improved arrival time picks. This provides a detailed seismicity image of the Mejillones region. Despite clear evidence for young active faults on Mejillones, upper crustal seismicity is only minor. Earthquakes along the interface occur continuously from 25 to 40km depth. Activity is also observed within the oceanic crust and is particularly high on the near-vertical rupture fault of a Mw6.8 intra-slab earthquake which followed only weeks after the 2007 Mw7.7 Tocopilla earthquake. Slab-related seismicity partly correlates with the coastline and is higher offshore. We also observe a North-South segmentation with a high level of seismicity at the northern and southern borders of the Mejillones Peninsula and less seismicity in its central part, both onshore and offshore.

  6. Erratic pollination, high selfing levels and their correlates and consequences in an altitudinally widespread above-tree-line species in the high Andes of Chile

    Science.gov (United States)

    Arroyo, Mary T. K.; Muñoz, María S.; Henríquez, Carolina; Till-Bottraud, Irène; Pérez, Fernánda

    2006-09-01

    Unfavorable temperatures and weather conditions for biotic pollination in above-tree-line alpine habitats predict self-compatibility, high levels of autogamy and small flower size ("autogamy reproductive assurance hypothesis"), or alternatively, compensatory measures such as greater flower longevity and larger display size so as to capture scarce visits and maintain outcrossing ("increased pollination probability hypothesis"). We assess these possibilities in a fine-tuned study of Chaetanthera euphrasioides (Asteraceae) populations located above-tree-line in the Andes of central Chile, where prior, independently obtained information on community flower visitation rates is available. Visitation by flies and Andrenid bees was highly erratic in all populations and among years, and the rates well below the community averages. We found evidence for high levels of self-compatibility, equally high autogamous potential, low genetic diversity and high and similar F IS in all populations studied, associated with no clear trends in floral morphology. Strong decoupling of C. euphrasioides reproductive biology with community-level pollinator availability in the alpine fails to support either of the above-mentioned hypotheses and suggests early acquisition of autogamy with present-day pollinator conditions being adequate to maintain low visitation rates at all elevations. Our study provides the only instance where alternative hypotheses on alpine breeding systems have been tested with prior access to independently quantified community-level flower visitation rates.

  7. Positive interactions between alpine plant species and the nurse cushion plant Laretia acaulis do not increase with elevation in the Andes of central Chile.

    Science.gov (United States)

    Cavieres, Lohengrin A; Badano, Ernesto I; Sierra-Almeida, Angela; Gómez-González, Susana; Molina-Montenegro, Marco A

    2006-01-01

    In alpine habitats, positive interactions among plants tend to increase with elevation as a result of altitudinal increase in environmental harshness. However, in mountains located in arid zones, lower elevations are also stressful because of scarce availability of water, suggesting that positive interactions may not necessarily increase with elevation. Here we analysed the spatial association of plant species with the nurse cushion plant Laretia acaulis at two contrasting elevations, and monitored the survival of seedlings of two species experimentally planted within and outside cushions in the semiarid Andes of central Chile. Positive spatial associations with cushions were more frequent at lower elevations. Species growing at the two elevations changed the nature of their association with cushions from neutral or negative at higher elevations to positive at lower elevations. Survival of seedlings was higher within cushions, particularly at lower elevations. The increased facilitation by cushions at lower elevations seems to be related to provision of moisture. This result suggests that cushion plants play a critical role in structuring alpine plant communities at lower elevations, and that climatic changes in rainfall could be very relevant for persistence of plant communities. PMID:16390419

  8. Ten new species from the Patagonian Andes (Argentina and Chile), mostly belonging to a newly designated Stigmella purpurimaculae group (Lepidoptera: Nepticulidae).

    Science.gov (United States)

    Stonis, Jonas R; Remeikis, Andrius; Davis, Donald R

    2014-01-01

    Ten new Stigmella Schrank species are described: Stigmella purpurimaculae Remeikis & Stonis, sp. nov., S. cana Remeikis & Stonis, sp. nov., S. truncata Remeikis & Stonis, sp. nov., S. sceptra Remeikis & Stonis, sp. nov., S. concreta Remeikis & Stonis, sp. nov., S. pseudoconcreta Remeikis & Stonis, sp. nov., S. quadrata Remeikis & Stonis, sp. nov. (all belonging to the newly designated S. purpurimaculae group), and S. semilactea Remeikis & Stonis, sp. nov., S. brutea Remeikis & Stonis, sp. nov., S. pseudodigitata Remeikis & Stonis, sp. nov. (not attributed to a species group) are described from the Andes (Patagonia: Argentina and Chile). For the species of the purpurimaculae group, a partial reduction of phallus, dentate cornuti, and strong development of utriculus (which can be equal or longer of the corpus bursae) are characteristic. Some of the species of the purpurimaculae group were collected near Nothofagus pumilio (Poepp. & Endl.) Krasser, Nothofagaceae, but there is still no confirmation that Nothofagus is a host-plant. All new Stigmella species are illustrated with photographs and drawings of the adults and genitalia. PMID:25543936

  9. A review of the non-bulimulid terrestrial Mollusca from the Region of Atacama, northern Chile

    OpenAIRE

    Juan Francisco Araya; Ricardo Catalán

    2014-01-01

    Abstract Terrestrial mollusca are sparsely studied in Chile and, for the first time, a formal record of the diversity of land snails in northern Chile is reported. Coastal and desertic areas in the Region of Atacama, in the border of the Atacama desert and the Pacific Ocean, were surveyed with the aim to describe the presence and distribution of this poorly known fauna. Of the fourteen species recorded, the geographic distribution records for nine species are extended, and some taxa are recor...

  10. Chile.

    Science.gov (United States)

    1986-04-01

    In 1985, Chile's population stood at 12 million, with an annual growth rate of 1.7%. 1984's infant mortality rate was 20/1000 live births and life expectancy was 67 years. The literacy rate was 94%. Of the work force of 3,841,000 in 1985, 15.9% were engaged in agriculture, forestry, and fishing; 31.3% were employed in industry and commerce; 38.6% were in the service sector; 8.7% worked in mining; and 4.4% were employed in construction. Chile's military junta is scheduled to be replaced by an elected legislature in 1990. The GDP was US $19.2 billion in 1984, with an annual real growth rate of 6.3%, and per capita GDP stood at US$1590. Inflation averages 23%. Industry comprises 21% of the GDP. Longterm prospects for the Chilean economy are influenced by a high debt service ratio, very low domestic savings and investment, the prospect of little or no increase in copper prices, and continuing problems in the domestic financial sector. In 1985-88, under the International Monetary Fund macroeconomic program, Chile will strive for moderate economic growth while managing its external debt servicing burden. PMID:12178144

  11. Recent crustal deformation in the Antofagasta region (northern Chile) and the subduction process

    OpenAIRE

    Delouis, B.; Philip, H.; Dorbath, Louis; Cisternas, A.

    1998-01-01

    New neotectonic observations, along with a detailed aerial photograph analysis, allow a new interpretation of the recent tectonic behaviour of the outer forearc in northern Chile between 22.5°S and 24.5°S (Antofagasta region). Both the Coastal Cordillera and the Mejillones Peninsula are under E-W extension. Normal faults dipping east with an almost N-S orientation are predominant. Large-scale Neogene to Recent deformation is characterized by vertical uplift and subsidence related to normal fa...

  12. A new freshwater snail (Caenogastropoda: Cochliopidae) from the Atacama Desert, northern Chile.

    Science.gov (United States)

    Collado, Gonzalo A

    2015-01-01

    In the family Cochliopidae, Heleobia Stimpson, 1865 is the most speciose genus in South America, with about 90 species (Hershler & Thompson 1992; Cazzaniga 2011). A recent molecular and morphological analysis performed in northern Chile (Atacama Desert) showed that the previously undescribed springsnails from Aguada de Chorrillos belong to Heleobia (Collado et al. 2013). In this study I formally describe this new species. Although this paper does not treat morphology in detail, the anatomical characters, in combination with the previously published molecular data provides a strong basis for recognizing this population as a distinct species. PMID:25781755

  13. U-series dating of co-seismic gypsum and submarine paleoseismology of active faults in Northern Chile (23°S)

    Science.gov (United States)

    Vargas, Gabriel; Palacios, Carlos; Reich, Martin; Luo, Shangde; Shen, Chuan-Chou; González, Gabriel; Wu, Yi-Chen

    2011-01-01

    The convergence of the Nazca and South American plates along the subduction margin of the central Andes results in large subduction earthquakes and tectonic activity along major fault systems. Despite its relevance, the paleoseismic record of this region is scarce, hampering our understanding about the relationship between the Andes building and earthquake occurrence. In this study, we used the U-series disequilibrium method to obtain absolute ages of paleoearthquake events associated with normal displacements along the active Mejillones and Salar del Carmen faults in the Coastal Range of the Atacama Desert of northern Chile. The 230Th- 234U disequilibrium ages in co-seismic gypsum salts sampled along the fault traces together with marine evidences indicate that earthquakes occurred at ca. 29.7 ± 1.7 ka, 11 ± 4 ka and 2.4 ± 0.8 ka. When coupled with paleoseismic marine and radiocarbon ( 14C) records in the nearby Mejillones Bay evidencing large dislocations along the Mejillones Fault, the geochronological dataset presented here is consistent with the notion that gypsum salts formed during large earthquakes as a result of co-seismic dilatancy pumping of saline waters along the major faults. Based on maximum observed cumulative vertical offsets in the studied faults, this phenomena could have occurred episodically at a rate in the order of 1:40 to 1:50 with respect to the very large subduction earthquakes during the latest Pleistocene-Holocene period. The results presented here reveal that the U-series disequilibrium method can be successfully applied to date the gypsum salts deposited along faults during seismic events, and therefore directly constrain the age of large paleoearthquakes in hyperarid and seismically active zones.

  14. Controls on the isotopic composition of surface water and precipitation in the Northern Andes, Colombian Eastern Cordillera

    Science.gov (United States)

    Saylor, Joel E.; Mora, Andrés; Horton, Brian K.; Nie, Junsheng

    2009-12-01

    Empirical datasets provide the constraints on the variability and causes of variability in stable isotope compositions (δD or δ 18O) of surface water and precipitation that are essential not only for models of modern and past climate but also for investigations of paleoelevation. This study presents stable isotope data for 76 samples from four elevation transects and three IAEA GNIP stations in the Eastern Cordillera of Colombia and the northern Andean foreland. These data are largely consistent with theories of stable isotope variability developed based on a global dataset. On a monthly basis, the precipitation-amount effect exerts the dominant control on δD p and δ 18O p values at the IAEA GNIP stations. At the Bogotá station (2547 m), the δD p and δ 18O p values vary seasonally, with isotopic minima correlating with maxima in precipitation-amount. Although surface water samples from Eastern Cordilleran streams and rivers fall on the Global Meteoric Water Line, samples from three of four lakes (2842-3459 m) have evaporatively elevated δD sw and δ 18O sw values. The IAEA GNIP station data averaged over multiple years, combined with stream and river water data, define vertical lapse rates of -1.8‰ km -1 for Δδ 18O and -14.6‰ km -1 for ΔδD, and are a close fit to a common thermodynamically based Rayleigh distillation model. Elevation uncertainties for these relationships are also evaluated. Comparison of this Colombian dataset with the elevation uncertainties generated by the thermodynamically based model shows that the model underestimates uncertainty at high Δδ 18O and ΔδD values while overestimating it for low Δδ 18O and ΔδD values. This study presents an independent, empirical assessment of stable isotope-based elevation uncertainties for the northern Andes based on a dataset of sufficient size to ensure statistical integrity. These vertical lapse rates and associated uncertainties form the basis for stable isotope paleoelevation studies

  15. Sediment yield along the Andes: continental budget, regional variations, and comparisons with other basins from orogenic mountain belts

    Science.gov (United States)

    Latrubesse, Edgardo M.; Restrepo, Juan D.

    2014-07-01

    We assess the sediment yield at 119 gauging stations distributed from Colombia to Patagonia, covering the different morphotectonic and morphoclimatic settings of the Andes. The most productive areas are the Meta River basin within the northern Andes and the Bolivian and northern Argentina-Chaco systems, which produce an average of 3345, 4909 and 2654 t km2 y- 1 of sediment, respectively. The rivers of the northern and central Andes (excluding the Pacific watersheds of Peru, northern Chile, and central Argentina) have a weighted mean sediment yield of 2045 t km- 2 y- 1 and produce 2.25 GTy- 1 of total sediment. A major constraint estimating the Andean continental budget of sediment yield lies in the lack of gauging data for the Peruvian region. Using the available gauge stations, the regional sediment yield appears underestimated. Assuming a higher value of sediment yield for the Peruvian Andes, the total budget for the whole central Andes could range between 2.57 GT y- 1 and 3.44 GT y- 1. A minimum of ~ 0.55 GT y- 1 and a probable maximum of ~ 1.74 GT y- 1 of sediment are deposited in the intramontane and surrounding proximal sedimentary basins. The magnitude of sediment yield in the Andes is comparable to other rivers draining orogenic belts around the world.

  16. Ages and geochemistry of Mesozoic-Eocene back-arc volcanic rocks in the Aysén region of the Patagonian Andes, Chile

    Directory of Open Access Journals (Sweden)

    Miguel A. Parada

    2001-07-01

    Full Text Available Eighteen new radiometric ages (fourteen 40Ar-39Ar, four K-Ar, combined with previously published ages, confirm the existence of three main extensional back-arc volcanic events, previously defined by stratigraphic relationships, in Chilean Patagonia (Aysén region. These three events developed during the Middle Jurassic -Early Cretaceous (160-130 Ma. Cretaceous (114-75 Ma, and Eocene (55-46 Ma. Based on distinct geochemical data and Sr-Nd isotopic characteristics of the back-arc volcanic rocks collected north and south of 46°30'S, two Mesozoic-Eocene magmatic domains are recognized: Northern Magmatic Domain (NMD and Southern Magmatic Domain (SMD. Most analyzed basalts and intermediate volcanic rocks of the NMD have alkaline affinities and depleted to slightly depleted Sr-Nd isotopic values similar to those derived from an asthenosphere-dominated source. The SMD mafic volcanic rocks have a subalkaline character and more enriched Sr-Nd isotopic signatures, comparable to those derived from a lithospheric source. The felsic volcanic rocks of the SMD have lower eNd values and slightly higher initial 87Sr/86Sr ratios than the NMD felsic rocks, suggesting a larger crustal contribution in the magma sources. The geochemical and isotopic distinction between NMD and SMD felsic rocks could be influenced by the presence of Paleozoic metamorphic rocks as basement of the volcanic rocks of the SMD. Moreover, the compositional distinction between basalts of both domains may correspond to differences in magnitude of extension, the NMD being the one where the extension would have been greater and, consequently, the lithosphere thinnerEdades y geoquímica de las rocas volcánicas del trasarco del Mesozoico-Eoceno en la región de Aysén de los Andes patagónicos, Chile. Diez y ocho nuevas edades radiométricas (catorce 40Ar-39Ar, cuatro K-Ar junto con las ya publicadas confirman la existencia de tres eventos volcánicos (previamente definidos por relaciones

  17. Cenozoic evolution of the northwestern Salar de Atacama Basin, northern Chile

    Science.gov (United States)

    Pananont, P.; Mpodozis, C.; Blanco, N.; Jordan, T. E.; Brown, L. D.

    2004-12-01

    Since 90 Ma, the nonmarine Salar de Atacama Basin has been the largest, deepest, and most persistent sedimentary basin of northern Chile. Integration of 200 km of two-dimensional seismic reflection data with surface geological data clarifies Oligocene and Neogene evolution of the northern part of the basin. A normal fault with 6 ± 1 km of vertical separation controlled the western boundary of the basin during the accumulation of the Oligocene-lower Miocene Paciencia Group. The combination of this structure, a similar one in the Calama Basin, and regional structural data suggests that localized extension played an important role within a tectonic environment dominated by margin-perpendicular compression and margin-parallel strike-slip deformation. Seismic data substantiate the surface interpretation that much of the Cordillera de la Sal ridge resulted from diapiric flow of the Paciencia Group. Diapiric flow initiated during the late early Miocene or middle Miocene, associated with a deep reverse fault.

  18. A Regional GIS of the Central Andes, South America - Integration of Satellite and Geophysical Data Sets

    OpenAIRE

    Hofmann, K; F. K. List;  

    1996-01-01

    The Central Andes of northern Chile, southwestern Bolivia and northwestern Argentina are studied by a research project supported by the Deutsche Forschungsgemeinschaft (SFB 267). The main topics of these geological and geophysical investigations are the orogeny of the Andean mountains and the crustal development at an active continental margin. The "Andean GIS" is designed as a tool for data collection, management, overview, analysis and mapping. The integration of different data supports the...

  19. Diversity of Bacteroidetes in high-altitude saline evaporitic basins in northern Chile

    Science.gov (United States)

    Dorador, Cristina; Meneses, Daniela; Urtuvia, Viviana; Demergasso, Cecilia; Vila, Irma; Witzel, Karl-Paul; Imhoff, Johannes F.

    2009-06-01

    The phylum Bacteroidetes represents one of the most abundant bacterial groups of marine and freshwater bacterioplankton. We investigated the diversity of Bacteroidetes in water and sediment samples from three evaporitic basins located in the highlands of northern Chile. We used both 16S rRNA gene clone libraries created with targeted Bacteroidetes-specific primers and separation of specifically amplified gene fragments by denaturing gradient gel electrophoresis (DGGE). DGGE analysis revealed a reduced richness of these organisms in samples from Salar de Huasco (two to four DGGE bands) increasing in Salar de Ascotán (two to seven DGGE bands) and Laguna Tebenquiche at Salar de Atacama (four to eight DGGE bands). Cluster analysis (WPGMA) of DGGE bands showed that bands from Salar de Huasco and Salar de Ascotán grouped together and samples from Salar de Atacama formed separate clusters in water and sediment samples, reflecting different Bacteroidetes communities between sites. Most of the sequences analyzed belonged to the family Flavobacteriaceae and clustered with the genera Psychroflexus, Gillisia, Maribacter, Muricauda, Flavobacterium, and Salegentibacter. The most abundant phylotype was highly related to Psychroflexus spp. and was recovered from all three study sites. The similarity of the analyzed sequences with their closest relatives in GenBank was typically Culture efforts will be necessary to get a better description of the diversity of this group in saline evaporitic basins of northern Chile.

  20. Strong motion simulation for mega-earthquakes in northern Chile from several potential rupture scenarios

    Science.gov (United States)

    Otarola, C., Sr.; Ruiz, S.

    2015-12-01

    Large earthquakes happened recently in Northern Chile: Tocopilla 2007 (Mw 7.7) and Iquique 2014 (Mw 8.1). Both events were well recorded by strong motion networks, provided valuable information to be used for forward predictions of ground motions records. In traditional finite-fault stochastic method one generic horizontal component of the synthetic accelerograms are obtained considering only incident vertical rays of S waves. The observed strong motion records show important differences among horizontal and vertical components. Then in order to generate 3 components of strong motion we improve this method to simulate the arrive to free surface of the P, SV and SH waves. We considered the incident and azimuth angles of direct seismic rays propagating for a layered velocity model including the free surface and energy partition. We validate our strong ground motion simulation by comparing the synthetic and observed data in a wide frequency range (0.1-20 Hz) for the Tocopilla (2007) and Iquique (2014) earthquakes. Finally, we use this method to propose the synthetic accelerograms for several potential rupture scenarios for mega-earthquakes in northern Chile, these scenarios were proposed considering coupling models and the historical earthquake records. The results show large PGA values near 1 g, for station located on hard rock. An important trade - off between the PGA and the proposed slip distribution was observed. The maximum slip distribution located in deeper seismogenic contact produce the large PGA in the nearest stations.

  1. Estimating glacier and snowmelt contributions to stream flow in a Central Andes catchment in Chile using natural tracers

    Directory of Open Access Journals (Sweden)

    M. Rodriguez

    2014-07-01

    Full Text Available This paper presents a methodology for hydrograph separation in high elevation watersheds, which aims at identifying individual flow sources such as snow- and ice melt, rainfall and soil water. Daily summer and bi-daily spring water samples from the outlet of the Juncal River were analyzed for all major ions as well as stable water isotopes, δ18O and δ2H. Additionally, various water sources such as rain, springs, snow- and glacial melt were sampled throughout the catchment. A principal component analysis (PCA was performed in order to reduce the dimensionality of the problem. Potential sources were identified in a two-component U space that explains 77% of variability. Hydrograph separation (HS was performed through three models: (i Isotopic model, (ii Mixing–PCA model, and (iii Informative–Bayesian model, with very similar results in each case. At the Juncal River outlet, summer flows were composed by at least 50% of water originating in highly glaciarized headwaters in 2011–2012 (a dry period in the Central Andes. Autumn and winter flows were highly influenced by soil water and affect total annual discharge. Before the high flow season, snow melt accounted for approximately 25% of streamflow, However during summer, when streamflow was highest, snowmelt contribution was minimal, while glacier melt and soil water were the most important sources.

  2. A new species of Phymaturus of the P. mallimaccii Group from the Andes of central Chile (Iguania: Liolaemidae

    Directory of Open Access Journals (Sweden)

    Jaime Troncoso-Palacios

    2014-08-01

    Full Text Available A new species of Phymaturus from the Provincia Mountain in the San Ramón Mountains in the Metropolitan Region of Chile is described. It is a member of the P. palluma Group and the P. mallimaccii subgroup. The new species can be distinguished from other members of the P. mallimaccii subgroup by having a highly fragmented subocular scale (4 or 5, a preocular scale that is smaller than the canthal, males having a olive dorsum with a diffuse pattern of light bands on the paravertebral fields and a light triangle between the shoulders, which has the apex of the triangle oriented toward the snout. The distribution of new species lies south of that of other members of the P. mallimaccii subgroup, from which it is completely isolated. The low abundance of the new species is noteworthy. Information about the natural history of the lizard is provided and some aspects of unnamed populations of Chilean Phymaturus are discussed.

  3. Hydrogeochemistry and stable isotopes of ground and surface waters from two adjacent closed basins, Atacama Desert, northern Chile

    Science.gov (United States)

    Alpers, C.N.; Whittemore, D.O.

    1990-01-01

    The geochemistry and stable isotopes of groundwaters, surface waters, and precipitation indicate different sources of some dissolved constituents, but a common source of recharge and other constituents in two adjacent closed basins in the Atacama Desert region of northern Chile (24??15???-24??45???S). Waters from artesian wells, trenches, and ephemeral streams in the Punta Negra Basin are characterized by concentrations of Na>Ca>Mg and Cl ???SO4, with TDS Mg ??? Ca and SO4 > Cl, with TDS also Mg ??? Ca and SO4 > Cl, but with TDS up to 40 g/l. The deep mine waters have pH between 3.2 and 3.9, and are high in dissolved CO2 (??13 C = -4.8%PDB), indicating probable interaction with oxidizing sulfides. The deep mine waters have ??18O values of ???-1.8%.compared with values < -3.5??? for other Hamburgo Basin waters; thus the mine waters may represent a mixture of meteoric waters with deeper "metamorphic" waters, which had interacted with rocks and exchanged oxygen isotopes at elevated temperatures. Alternatively, the deep mine waters may represent fossil meteoric waters which evolved isotopically along an evaporative trend starting from values quite depleted in ??18O and ??Dd relative to either precipitation or shallow groundwaters. High I/Br ratios in the Hamburgo Basin waters and La Escondida mine waters are consistent with regionally high I in surficial deposits in the Atacama Desert region and may represent dissolution of a wind-blown evaporite component. Rain and snow collected during June 1984, indicate systematic ??18O and ??D fractionation with increasing elevation between 3150 and 4180 m a.s.l. (-0.21??.??18O and -1.7??.??D per 100 m). Excluding the deep mine waters from La Escondida, the waters from the Hamburgo and Punta Negra Basins have similar ??D and ??18O values and together show a distinct evaporative trend (??D = 5.0 ??18O - 20.2). Snowmelt from the central Andes Cordillera to the east is the most likely source of recharge to both basins. Some of the

  4. Physical, chemical and mineralogical evolution of the Tolhuaca geothermal system, southern Andes, Chile: Insights into the interplay between hydrothermal alteration and brittle deformation

    Science.gov (United States)

    Sanchez-Alfaro, Pablo; Reich, Martin; Arancibia, Gloria; Pérez-Flores, Pamela; Cembrano, José; Driesner, Thomas; Lizama, Martin; Rowland, Julie; Morata, Diego; Heinrich, Christoph A.; Tardani, Daniele; Campos, Eduardo

    2016-09-01

    In this study, we unravel the physical, chemical and mineralogical evolution of the active Tolhuaca geothermal system in the Andes of southern Chile. We used temperature measurements in the deep wells and geochemical analyses of borehole fluid samples to constrain present-day fluid conditions. In addition, we reconstructed the paleo-fluid temperatures and chemistry from microthermometry and LA-ICP-MS analysis of fluid inclusions taken from well-constrained parageneses in vein samples retrieved from a ~ 1000 m borehole core. Based on core logging, mineralogical observations and fluid inclusions data we identify four stages (S1-S4) of progressive hydrothermal alteration. An early heating event (S1) was followed by the formation of a clay-rich cap in the upper zone (inhibited. In contrast, in the deep upflow zone the less pervasive formation of clay mineral assemblages has allowed retention of rock strength and dilatant behavior during slip, sustaining high permeability conditions. Numerical simulations of heat and fluid flows support our observations and suggest that the presence of a low permeability clay cap has helped increase the duration of high-enthalpy conditions by a factor of three in the deep upflow zone at Tolhuaca geothermal system, when compared with an evolutionary scenario where a clay cap was not developed. Furthermore, our data demonstrate that the dynamic interplay between fluid flow, crack-seal processes and hydrothermal alteration are key factors in the evolution of the hydrothermal system, leading to the development of a high enthalpy reservoir at the flank of the dormant Tolhuaca volcano.

  5. Expanding Geophysical and Geochemical Investigation of Causes of Extraordinary Unrest at the Laguna del Maule (Rhyolitic) Volcanic Field, Southern Andes, Chile

    Science.gov (United States)

    Singer, B. S.

    2014-12-01

    The Laguna del Maule Volcanic Field, Chile, includes an unusually large and recent concentration of silicic eruptions. Since 2007 the crust here has been inflating at an astonishing rate of 25 cm/yr. Findings thus far lead to the hypothesis that the silicic vents have tapped an extensive layer of crystal-poor, rhyolitic melt that began to form atop a magmatic mush zone that was established by ~20 ka with a renewed phase of rhyolite eruptions during the Holocene. Modeling of surface deformation, magnetotelluric data, and gravity changes suggest that magma is currently intruding at a depth of ~5 km. Swarms of volcano-tectonic and long period earthquakes, mostly of M Nanyang Technological University-Singapore, SERNAGEOMIN, OVDAS, USGS, and SEGEMAR-Argentina. Team members will be introduced in this presentation. Our approach includes augmenting the OVDAS array of 6 permanent seisic stations with 40 additional instruments to conduct tomographic, receiver function and ambient noise studies. We continue to collect 4-D gravity data from 37 stations. Surface deformation is monitored via cGPS at 5 permanent receivers and InSAR data. A magnetotelluric survey across the Andes at 36o S is planned. Geochemical studies include mineral zoning and U-Th disequilibrium of zircons to constrain the timing of magma intrusion and mixing events prior to the current unrest. The overall aim is to integrate these observations and to construct numerical models of system dynamics. We are developing communications protocols and a web site to facilitate sharing of findings among the team members and with the public.

  6. Physical, chemical and mineralogical evolution of the Tolhuaca geothermal system, southern Andes, Chile: Insights into the interplay between hydrothermal alteration and brittle deformation

    Science.gov (United States)

    Sanchez-Alfaro, Pablo; Reich, Martin; Arancibia, Gloria; Pérez-Flores, Pamela; Cembrano, José; Driesner, Thomas; Lizama, Martin; Rowland, Julie; Morata, Diego; Heinrich, Christoph A.; Tardani, Daniele; Campos, Eduardo

    2016-09-01

    In this study, we unravel the physical, chemical and mineralogical evolution of the active Tolhuaca geothermal system in the Andes of southern Chile. We used temperature measurements in the deep wells and geochemical analyses of borehole fluid samples to constrain present-day fluid conditions. In addition, we reconstructed the paleo-fluid temperatures and chemistry from microthermometry and LA-ICP-MS analysis of fluid inclusions taken from well-constrained parageneses in vein samples retrieved from a ~ 1000 m borehole core. Based on core logging, mineralogical observations and fluid inclusions data we identify four stages (S1-S4) of progressive hydrothermal alteration. An early heating event (S1) was followed by the formation of a clay-rich cap in the upper zone (creation or reactivation of highly permeable extensional fractures is inhibited. In contrast, in the deep upflow zone the less pervasive formation of clay mineral assemblages has allowed retention of rock strength and dilatant behavior during slip, sustaining high permeability conditions. Numerical simulations of heat and fluid flows support our observations and suggest that the presence of a low permeability clay cap has helped increase the duration of high-enthalpy conditions by a factor of three in the deep upflow zone at Tolhuaca geothermal system, when compared with an evolutionary scenario where a clay cap was not developed. Furthermore, our data demonstrate that the dynamic interplay between fluid flow, crack-seal processes and hydrothermal alteration are key factors in the evolution of the hydrothermal system, leading to the development of a high enthalpy reservoir at the flank of the dormant Tolhuaca volcano.

  7. New estimated Holocene denudation rates for non-glaciated areas in the southernmost Patagonian Andes (53°S), Chile

    Science.gov (United States)

    Breuer, Sonja; Kilian, Rolf; Baeza, Oscar; Arz, Helge

    2010-05-01

    Cenozoic denudation rates are sparsely known for the southernmost Patagonian Andes. One of the scientific approaches is to calculate long-term denudation rates based on fission track analyses. Though, these average rates comprise a long period with distinct climate conditions and very different extend of glaciation. These integrated denudation rates include extensive surface areas with different morphological, glacial and vegetational properties. In contrast, our approach is restricted to relative short Holocene periods and small catchment areas, for which the denudation and its controlling surface characteristics could be defined more precisely. Thus a more precise evaluation of the influencing parameters like climate, morphology and vegetation cover was possible. We concentrated on three restricted and nearly closed areas of denudation and accumulation. In those catchments we determined the sediment masses of lakes, based on sediment drilling, echosounding and computer based interpolation of the siliciclastic sediment masses. These masses were transferred to the denudation areas which have been characterised and measured by remote sensing. The westernmost Tamar Lake is located on the Tamar Island in the western part of the Magellan Strait, where the annual precipitation is about 4,000 mm. The catchment area has a dense vegetation cover. The lake surrounding slopes reach an elevation of 400 m a.s.l and they are up to 60° steep. The calculated denudation rate for this catchment is about 2.56 mm/ka, which represents a minimum value, because the postglacial weathering horizon is only partly removed into the lake. The highest elevated lake Muy Profundo (500 m a.s.l.) possesses a denudation area with a nearly vegetation-free zone up to 750 m a.s.l. within the Patagonian Batholith. The catchment area of this lake is characterised by a roche moutonnée landform with steep slopes and active fracture zones. The precipitation varies between 5,000 and 8,000 mm/a. The

  8. First host plant records for Iridopsis hausmanni Vargas (Lepidoptera, Geometridae in the coastal valleys of northern Chile

    Directory of Open Access Journals (Sweden)

    Héctor A. Vargas

    2014-03-01

    Full Text Available First host plant records for Iridopsis hausmanni Vargas (Lepidoptera, Geometridae in the coastal valleys of northern Chile. The trees Haplorhus peruviana Engl. and Schinus molle L. (Anacardiaceae are mentioned as the first host plant records for the little known native moth Iridopsis hausmanni Vargas, 2007 (Lepidoptera, Geometridae, Ennominae in the coastal valleys of the northern Chilean Atacama Desert. This is also the first record of Anacardiaceae as host plant for a Neotropical species of Iridopsis Warren, 1894.

  9. First host plant records for Iridopsis hausmanni Vargas (Lepidoptera, Geometridae) in the coastal valleys of northern Chile

    OpenAIRE

    2014-01-01

    First host plant records for Iridopsis hausmanni Vargas (Lepidoptera, Geometridae) in the coastal valleys of northern Chile. The trees Haplorhus peruviana Engl. and Schinus molle L. (Anacardiaceae) are mentioned as the first host plant records for the little known native moth Iridopsis hausmanni Vargas, 2007 (Lepidoptera, Geometridae, Ennominae) in the coastal valleys of the northern Chilean Atacama Desert. This is also the first record of Anacardiaceae as host plant for a Neotropical species...

  10. Arc-oblique fault systems: their role in the Cenozoic structural evolution and metallogenesis of the Andes of central Chile

    Science.gov (United States)

    Piquer, Jose; Berry, Ron F.; Scott, Robert J.; Cooke, David R.

    2016-08-01

    The evolution of the Main Cordillera of Central Chile is characterized by the formation and subsequent inversion of an intra-arc volcano-tectonic basin. The world's largest porphyry Cu-Mo deposits were emplaced during basin inversion. Statistically, the area is dominated by NE- and NW-striking faults, oblique to the N-striking inverted basin-margin faults and to the axis of Cenozoic magmatism. This structural pattern is interpreted to reflect the architecture of the pre-Andean basement. Stratigraphic correlations, syn-extensional deposits and kinematic criteria on fault surfaces show several arc-oblique structures were active as normal faults at different stages of basin evolution. The geometry of syn-tectonic hydrothermal mineral fibers, in turn, demonstrates that most of these structures were reactivated as strike-slip ± reverse faults during the middle Miocene - early Pliocene. Fault reactivation age is constrained by 40Ar/39Ar dating of hydrothermal minerals deposited during fault slip. The abundance and distribution of these minerals indicates fault-controlled hydrothermal fluid flow was widespread during basin inversion. Fault reactivation occurred under a transpressive regime with E- to ENE-directed shortening, and was concentrated around major plutons and hydrothermal centers. At the margins of the former intra-arc basin, deformation was largely accommodated by reverse faulting, whereas in its central part strike-slip faulting was predominant.

  11. Long-term erosion and exhumation of the “Altiplano Antioqueño”, Northern Andes (Colombia) from apatite (U Th)/He thermochronology

    Science.gov (United States)

    Restrepo-Moreno, Sergio A.; Foster, David A.; Stockli, Daniel F.; Parra-Sánchez, Luis N.

    2009-02-01

    The Antioqueño Plateau (AP) in the northern Cordillera Central, Colombia, is the largest high elevation erosional surface in the Northern Andes. Apatite (U-Th)/He thermochronometry (AHe) of samples collected from two elevation profiles spanning ˜ 2 km of exhumed crustal sections reveal the long-term erosional exhumation of the AP. Sample profiles exhibit AHe ages that increase with elevation from ca. 22 Ma (˜ 760 m) at the bottom of regional scarps to ca. 49 Ma (˜ 2350 m) on top of the AP. A marked inflection point in age versus elevation data at ca. 25 Ma defines the bottom of the exhumed post-Oligocene He partial retention zone (He-PRZ). Elevation-invariant ages below ca. 25 Ma record the onset of rapid exhumation and surface uplift of the AP that led to river incision. A subtle change in slope within the He-PRZ, ca. 41 Ma, is interpreted as a less intense, exhumation-related cooling episode. These two exhumation pulses coincide with the Proto-Andina and Pre-Andina orogenic phases previously proposed for the Colombian Andes, and are synchronous with tectonically driven exhumation events reported for the Peruvian, Bolivian and Argentinean Andes, and for some orogenic systems in the Caribbean. The pulses are correlated with variations in the rates of convergence between Nazca (Farallon) and South America documented for the Middle Eocene and the Late Oligocene suggesting continental-scale controls on uplift and denudation throughout the Andean range. AHe data provide an average erosion rate of ˜ 0.04 mm/yr for the last 25 million years. Erosion rates during the exhumation pulses were in the order of ˜ 0.2-0.4 mm/yr. Similarity between AHe profiles indicates the whole AP was uplifted and exhumed as a coherent structural block, corroborating previous structural evidence for the rigidity and coherence of this crustal block in the Northern Andes. Our results are in agreement with tectonostratigraphic data in the Magdalena and Cauca basins and with proposed

  12. Testing for Changes in Crustal Velocity at the Tocopilla Earthquake, Northern Chile

    Science.gov (United States)

    Richter, T.; Asch, G.; Kind, R.

    2011-12-01

    We use two different techniques to investigate the region between Antofagasta and Arica in northern Chile for crustal velocity changes. Data are taken from the 19 broadband stations of the IPOC project (Integrated Plate Boundary Observatory Chile) operating partly since 2006 by GFZ and Institut de Physique du Globe de Paris (IPGP). In the neighborhood of the seismic stations an M7.0 earthquake occurred near Tocopilla on 14 November 2007. Other studies have shown that in the course of such earthquakes seismic velocities may be changing (e.g. Brenguier et al. 2008). The first method is testing for phase shifts in receiver functions. To avoid varying travel paths of different events we compare events located in small source regions. Although temporal variations have been found in receiver functions for the Parkfield M6.0 and San Simeon M6.5 earthquakes (Audet 2006) we cannot find any variations exceeding the noise level of our dataset at the time of the M7.0 earthquake near Tocopilla. Therefore the data is analyzed with the help of cross-correlation technique of ambient seismic noise (Bensen et al. 2007). Compared to the first method it has the advantage of regularly available correlation functions (e.g. 1 per day). We report on first results.

  13. Development of Ground and Remotely Based Evaporation Measurements at the Salar de Atacama, Northern Chile

    Science.gov (United States)

    Kampf, S. K.; Tyler, S. W.; Menz, S. F.; Muñoz, J. F.; Astete, C. O.

    2001-12-01

    Evaporation represents an important component of the water budget in desert playa lakes, and accurate spatial and temporal assessment of evaporation rates has the potential to greatly improve the accuracy of hydrologic models in such environments. To this end, evaporation at the Salar de Atacama, a large playa in the Atacama Desert of northern Chile, has been examined at a variety of spatial and temporal scales. Previous investigators have measured evaporation from the Salar using lysimeters and Bowen Ratio stations and have found that actual evaporation rates in much of the playa are extremely low (Salar are presented along with an assessment of the ability of ASTER imagery to provide accurate measurements of evaporation rates in playa environments.

  14. A new species of Eccopsis Zeller (Lepidoptera, Tortricidae from the coastal valleys of northern Chile, with the first continental record of E. galapagana Razowski & Landry

    Directory of Open Access Journals (Sweden)

    Héctor A. Vargas

    2011-06-01

    Full Text Available A new species of Eccopsis Zeller (Lepidoptera, Tortricidae from the coastal valleys of northern Chile, with the first continental record of E. galapagana Razowski & Landry. Eccopsis Zeller, 1852 is reported for the first time from Chile. Eccopsis razowskii Vargas, n. sp. is described and illustrated based on specimens reared from larvae collected on native Acacia macracantha Willd. (Fabaceae in the coastal valleys of the northern Chilean desert. Eccopsis galapagana Razowski & Landry, 2008, previously known only from the Galapagos Islands, Ecuador, is recorded for the first time from continental South America. Larvae of the latter were collected in northern Chile feeding on Prosopis alba Griseb (Fabaceae.

  15. Modelling the hydrological response of debris-free and debris-covered glaciers to present climatic conditions in the semiarid Andes of central Chile

    Science.gov (United States)

    Ayala, Alvaro; Pellicciotti, Francesca; MacDonell, Shelley; McPhee, James; Vivero, Sebastián; Campos, Cristián; Egli, Pascal

    2016-04-01

    We investigate the main contributors to runoff of a 62 km2 glacierized catchment in the semiarid Andes of central Chile, where both debris-free and debris-covered glaciers are present, combining an extensive set of field measurements, remote sensing products and an advanced glacio-hydrological model (TOPKAPI-ETH). The catchment contains two debris-free glaciers reaching down to 3900 m asl (Bello and Yeso Glaciers) and one debris-covered avalanche-fed glacier reaching to 3200 m asl (Piramide Glacier). A unique dataset of field measurements collected in the ablation seasons 2013-14 and 2014-15 included four automatic weather stations, manual measurements of snow depth and debris cover thickness, discharge measurements at glaciers outlets, photographic monitoring of surface albedo as well as ablation stakes measurements and snow pits. TOPKAPI-ETH combines physically-oriented parameterizations of snow and ice ablation, gravitational distribution of snow, snow albedo evolution, glacier dynamics, runoff routing and the ablation of debris-covered ice.We obtained the first detailed estimation of mass balance and runoff contribution of debris-covered glaciers in this mountainous region. Results show that while the mass balance of Bello and Yeso Glaciers is mostly controlled by air temperature lapse rates, the mass balance of Piramide Glacier is governed by debris thickness and avalanches. In fact, gravitational distribution by avalanching on wet years plays a key role and modulates the mass balance gradient of all glaciers in the catchment and can turn local mass balance from negative to positive. This is especially the case for Piramide Glacier, which shows large amounts of snow accumulation below the steep walls surrounding its upper area. Despite the thermal insulation effect of the debris cover, the contribution to runoff from debris-free and debris-covered glaciers is similar, mainly due to elevation differences. At the catchment scale, snowmelt represents more than 60

  16. The provenance of archaeological obsidian artifacts from Northern Chile determined by source-induced X-ray fluorescence

    International Nuclear Information System (INIS)

    A study of provenance of obsidian artifacts from 'site 25-Las Estacas', Quebrada de Jorquera (Copiapo, Northern Chile) was carried out by means of X-ray fluorescence, using radioactive sources. Obsidian samples from different Chilean geological regions, located in South Central Chile (Laguna del Maule volcanic area, sources of La Coloradas and La Plata), 'Radal Siete Tazas' and the North of Chile (Copiapo Volcano) were analyzed. The analysis was performed using 109Cd and 241Am annular excitation sources and X-ray fluorescence. This allowed the determination of Fe, Cu, Rb, Sr, Y, Zr, and Ba concentrations on samples of ground obsidian from the aforementioned sites. The measured Rb, Sr, and Zr concentrations were used to construct discriminant diagrams, which clearly showed clustering of the samples from the different sources, and the association of the archaeological obsidian sample to the Copiapo Volcano source, which is geographically close to the site. (author)

  17. Imaging Seismic Source Variations Using Back-Projection Methods at El Tatio Geyser Field, Northern Chile

    Science.gov (United States)

    Kelly, C. L.; Lawrence, J. F.

    2014-12-01

    During October 2012, 51 geophones and 6 broadband seismometers were deployed in an ~50x50m region surrounding a periodically erupting columnar geyser in the El Tatio Geyser Field, Chile. The dense array served as the seismic framework for a collaborative project to study the mechanics of complex hydrothermal systems. Contemporaneously, complementary geophysical measurements (including down-hole temperature and pressure, discharge rates, thermal imaging, water chemistry, and video) were also collected. Located on the western flanks of the Andes Mountains at an elevation of 4200m, El Tatio is the third largest geyser field in the world. Its non-pristine condition makes it an ideal location to perform minutely invasive geophysical studies. The El Jefe Geyser was chosen for its easily accessible conduit and extremely periodic eruption cycle (~120s). During approximately 2 weeks of continuous recording, we recorded ~2500 nighttime eruptions which lack cultural noise from tourism. With ample data, we aim to study how the source varies spatially and temporally during each phase of the geyser's eruption cycle. We are developing a new back-projection processing technique to improve source imaging for diffuse signals. Our method was previously applied to the Sierra Negra Volcano system, which also exhibits repeating harmonic and diffuse seismic sources. We back-project correlated seismic signals from the receivers back to their sources, assuming linear source to receiver paths and a known velocity model (obtained from ambient noise tomography). We apply polarization filters to isolate individual and concurrent geyser energy associated with P and S phases. We generate 4D, time-lapsed images of the geyser source field that illustrate how the source distribution changes through the eruption cycle. We compare images for pre-eruption, co-eruption, post-eruption and quiescent periods. We use our images to assess eruption mechanics in the system (i.e. top-down vs. bottom-up) and

  18. First remarks on the nesting biology of Hypodynerus andeus (Packard (Hymenoptera, Vespidae, Eumeninae in the Azapa valley, northern Chile

    Directory of Open Access Journals (Sweden)

    Felipe Méndez-Abarca

    2012-06-01

    Full Text Available First remarks on the nesting biology of Hypodynerus andeus (Packard (Hymenoptera, Vespidae, Eumeninae in the Azapa valley, northern Chile. Some aspects about the nesting biology of the potter wasp Hypodynerus andeus (Packard, 1869 are reported for the first time. Observations were carried out at the Azapa valley, coastal desert of northern Chile. A total of sixty nests were collected and examined, each composed by 1-14 cells, most of them found attached to concrete lamp posts. The only preys recorded in the cells were Geometridae (Lepidoptera caterpillars and the presence of the parasitoid Anthrax sp. (Diptera, Bombyliidae was also recorded. A number of arthropods belonging to different groups, mainly spiders, were found occupying empty nests.

  19. Draft genome sequence of chloride-tolerant Leptospirillum ferriphilum Sp-Cl from industrial bioleaching operations in northern Chile

    OpenAIRE

    Issotta, Francisco; Galleguillos, Pedro A.; Moya-Beltrán, Ana; Davis-Belmar, Carol S.; Rautenbach, George; Paulo C Covarrubias; Acosta, Mauricio; Ossandon, Francisco J.; Contador, Yasna; Holmes, David S; Marín-Eliantonio, Sabrina; Quatrini, Raquel; Demergasso, Cecilia

    2016-01-01

    Leptospirillum ferriphilum Sp-Cl is a Gram negative, thermotolerant, curved, rod-shaped bacterium, isolated from an industrial bioleaching operation in northern Chile, where chalcocite is the major copper mineral and copper hydroxychloride atacamite is present in variable proportions in the ore. This strain has unique features as compared to the other members of the species, namely resistance to elevated concentrations of chloride, sulfate and metals. Basic microbiological features and genomi...

  20. Detailed Ar-40/Ar-39 dating of geologic events associated with the Mantos Blancos copper deposit, northern Chile

    OpenAIRE

    Oliveros, V.; Feraud, G.; L. Aguirre; Ramirez, L.; Fornari, Michel; Palacios, C.; Parada, M.

    2008-01-01

    The Ar-40/Ar-39 geochronological method was applied to date magmatic and hydrothermal alteration events in the Mantos Blancos mining district in the Coastal Cordillera of northern Chile, allowing the distinction of two separate mineralization events. The Late Jurassic Mantos Blancos orebody, hosted in Jurassic volcanic rocks, is a magmatic-hydrothermal breccia-style Cu deposit. Two superimposed mineralization events have been recently proposed. The first event is accompanied by a phyllic hydr...

  1. Application of PIXE to the characterization of vitreous dacites from archaeolgical sites in the Atacama region in northern Chile

    International Nuclear Information System (INIS)

    Geochemical characterization studies using PIXE were carried out on 21 vitreous dacite artifacts from early formative archaeological sites in the Atacama region, in northern Chile, and on 13 samples taken from two potential volcanic sources located within the region. Performing statistical analyses it was possible to obtain elemental concentration patterns for the archaeological samples of this material and match some of these artifacts with the geological source samples

  2. Application of PIXE to the characterization of vitreous dacites from archaeolgical sites in the Atacama region in northern Chile

    Energy Technology Data Exchange (ETDEWEB)

    Morales, J.R.; Cancino, S. [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Nunoa, Santiago 1 (Chile); Miranda, P. [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Nunoa, Santiago 1 (Chile)], E-mail: pjmirand@gmail.com; Dinator, M.I. [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Nunoa, Santiago 1 (Chile); Seelenfreund, A. [Universidad Academia de Humanismo Cristiano, Condell 343, Providencia, Santiago (Chile)

    2007-11-15

    Geochemical characterization studies using PIXE were carried out on 21 vitreous dacite artifacts from early formative archaeological sites in the Atacama region, in northern Chile, and on 13 samples taken from two potential volcanic sources located within the region. Performing statistical analyses it was possible to obtain elemental concentration patterns for the archaeological samples of this material and match some of these artifacts with the geological source samples.

  3. Importance of water quality on plant abundance and diversity in high-alpine meadows of the Yerba Loca Natural Sanctuary at the Andes of north-central Chile Importancia de la calidad del agua sobre la abundancia y diversidad vegetal en vegas altoandinas del Santuario Natural Yerba Loca en los Andes de Chile centro-norte

    Directory of Open Access Journals (Sweden)

    ROSANNA GINOCCHIO

    2008-12-01

    Full Text Available Porphyry Cu-Mo deposits have influenced surface water quality in high-Andes of north-central Chile since the Miocene. Water anomalies may reduce species abundance and diversity in alpine meadows as acidic and metal-rich waters are highly toxic to plants The study assessed the importance of surface water quality on plant abundance and diversity in high-alpine meadows at the Yerba Loca Natural Santuary (YLNS, central Chile (33°15' S, 70°18' W. Hydrochemical and plant prospecting were carried out on Piedra Carvajal, Chorrillos del Plomo and La Lata meadows the growing seasons of 2006 and 2007. Direct gradient analysis was performed through canonical correspondence analysis (CCA to look for relationships among water chemistry and plant factors. High variability in water chemistry was found inside and among meadows, particularly for pH, sulphate, electric conductivity, hardness, and total dissolved Cu, Zn, Cd, Pb and Fe. Data on species abundance and water chemical factors suggests that pH and total dissolved Cu are very important factor determining changes in plant abundance and diversity in study meadows. For instance, Festuca purpurascens, Colobanthus quitensis, and Arenaria rivularis are abundant in habitals with Cu-rich waters while Festuca magellanica, Patosia clandestina, Plantago barbata, Werneria pygmea, and Erigeron andícola are abundant in habitals with dilute waters.Los megadepósitos de pórfidos de Cu-Mo han influido sobre la calidad de las aguas superficiales en las zonas altoandinas del centro-norte de Chile desde el Mioceno. Estas alteraciones en la calidad de las aguas podrían afectar negativamente a la vegetación presente en las vegas altoandinas, ya que las aguas acidas y ricas en metales son altamente tóxicas para las plantas. En este estudio se evaluó el efecto de la calidad de las aguas en la abundancia y diversidad florística de las vegas altoandinas del Santuario de la Naturaleza Yerba Loca (SNYL, en Chile central (33

  4. Ice elevation and areal changes of glaciers from the Northern Patagonia Icefield, Chile

    Science.gov (United States)

    Rivera, Andrés; Benham, Toby; Casassa, Gino; Bamber, Jonathan; Dowdeswell, Julian A.

    2007-10-01

    High thinning rates (up to - 4.0 ± 0.97 m a - 1 ) have been measured at Campo de Hielo Patagónico Norte (CHN) or Northern Patagonia Icefield, Chile between 1975 and 2001. Results have been obtained by comparing a Digital Elevation Model (DEM) derived from regular cartography compiled by Instituto Geográfico Militar of Chile (IGM) based upon 1974/1975 aerial photographs and a DEM generated from Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) satellite images acquired in September 2001. A complete cloud-free Landsat ETM+ satellite image mosaic acquired in March 2001 was used to update the available glacier inventory of the CHN, including all glaciers larger than 0.5 km 2 (48 new glaciers). A new delineation of ice divides was also performed over the accumulation areas of glaciers sharing the high plateau where the existing regular cartography exhibits poor coverage of topographic information. This updated glacier inventory produced a total ice area for 2001 of 3953 km 2, which represents a decrease of 3.4 ± 1.5% (140 ± 61 km 2 of ice) with respect to the total ice area of the CHN in 1979 calculated from a Landsat MSS satellite image. Almost 62% of the total area change between 1979 and 2001 took place in glaciers located at the western margin of the CHN, where the maximum area loss was experienced by Glaciar San Quintín with 33 km 2. At the southern margin, Glaciar Steffen underwent the largest ice-area loss (12 km 2 or 2.6% of the 1979 area), whilst at the eastern margin the greatest area loss took place in Glaciares Nef (7.9 km 2, 5.7% of the 1979 area) and Colonia (9.1 km 2, 2.7% of the 1979 area). At the northern margin of the CHN the lower debris-covered ablation area of Glaciar Grosse collapsed into a new freshwater lake formed during the late 1990s. The areal changes measured at the CHN are much larger than previously estimated due to the inclusion of changes experienced in the accumulation areas. The CHN as a whole is

  5. Geophysical Survey in Iquique and Alto Hospicio, northern Chile Cities: Tectonic and Geologic Implications.

    Science.gov (United States)

    García-Pérez, T.; Yanez, G. A.; Cembrano, J. M.; Marquardt, C.; Gomila, R.; Santibanez, I.; Maringue, J.

    2015-12-01

    The crustal deformation nature during the Cenozoic in northern Chile forearc (Coastal Cordillera; CC) is complex due to the several tectonics process involved, such as plate convergence, a continental orocline (Arica bend) and great degree of coupling between Nazca and South America plates. Such deformation could be regionally explained by an EW-extension generally accommodated by trench parallel faults system (TPFS). Also between ca. 19°-22° S, a small but significant NS-shortening produce folds and faults scarps striking orthogonal to plate boundary denominated trench-orthogonal faults system (TOFS). The main goal of this study is to understand the recent deformation history of the rocks units making up this part of the CC and the structural controls exerted on them by this fault systems. To achieve this, geophysical surveys have been conducted in Iquique and Alto Hospicio cities, both located in northern Chile. The results obtained by Gravity and Electromagnetics Transient (TEM) surveys are consistent with the nature and geometry of geological units previously identified in the zone. Sedimentary and intrusive rocks shows high values of density and resistivity, whereas volcanic rocks are associated with high values of density but low values of resistivity. This difference could be explained by water hosted by the fractured volcanic unit. Moreover, the sedimentary units are related to low values of density and resistivity. A first-order feature shown by the gravity anomaly is the existence of a NS sedimentary basin filled with gravels. However, this basin presents several discrete depocentres coinciding with EW faults. This could be interpreted as Quaternary deformation of the CC. TEM data shows changes in resistivity of the subsurface suggesting different relative levels for the same lithological units. These variations can be explained by normal or inverse movements of NS and EW faults that cut and displace all the units. In conclusion, results obtained from

  6. Floristic changes in alpine plant communities induced by the cushion plant Azorella madreporica (Apiaceae in the Andes of central Chile Cambios florísticos en comunidades de plantas alpinas inducidos por la planta en cojín Azorella madrepórica (Apiaceae en los Andes de Chile central

    Directory of Open Access Journals (Sweden)

    CONSTANZA L QUIROZ

    2009-06-01

    Full Text Available It is well known that the number of plant species associated with nurse plants increases with elevation. However, studies conducted so far have largely ignored the effect of nurse plants on other community attributes, such as the species abundances, diversity and evenness. Moreover, changes in these community attributes along environmental gradients have also been seldom examined. The present study evaluates the effect of the cushion plant Azorella madrepórica (Apiaceae on species richness, species abundance, diversity and evenness of vascular plants at two elevations in the Andes of central Chile. Theoretically, the impact of this nurse cushion plant on these community attributes should be grater at a higher elevation. Results showed that the proportion of plant species associated with cushion plants increases with elevation, and the abundance of some species is also greater within cushions than on bare ground. Although the proportion of species growing within cushions increased with elevation, diversity and evenness were higher on bare ground. This is due to some few species that attained very high densities within cushions, generating assemblages highly dominated by some few species. Ordination analyses indicated differences in species assemblages within and outside A. madrepórica at the higher elevation. Therefore, the influence of cushion plants on community structure changes with elevation. Accordingly, we suggest that attributes other than species richness must be included in future studies in order to analyze the impact of nurse species on community structure along environmental gradients.Se sabe que el número de especies asociado a plantas nodrizas aumenta con la altitud. Sin embargo, el efecto de plantas nodrizas sobre otros atributos de las comunidades, como la abundancia de especies, diversidad y equidad, ha sido largamente ignorado. Más aún, cambios en estos atributos en gradientes ambientales han sido pocas veces examinados

  7. Cenozoic subsurface stratigraphy and structure of the Salar de Atacama Basin, northern Chile

    Science.gov (United States)

    Jordan, T. E.; Mpodozis, C.; Muñoz, N.; Blanco, N.; Pananont, P.; Gardeweg, M.

    2007-02-01

    Sequence mapping of industry seismic lines and their correlation to exposed stratigraphic formations enable a description of the evolution of the nonmarine Salar de Atacama Basin. This major tectonic basin, located in the present-day forearc of the northern Chilean Andes, was first defined topographically by late Cretaceous inversion of the Jurassic-early Cretaceous extensional Tarapacá backarc Basin. Inversion led to both the uplift of the Cordillera de Domeyko and subsidence of the Salar de Atacama Basin along its eastern flank. The basin evolved from a continental backarc in the Cretaceous and Paleogene to a forearc tectonic setting during the Neogene. The principal causes of basin-scale tectonic subsidence include late Cretaceous and earliest Paleocene shortening and Oligocene-early Miocene localized extension. The basin was not completely filled by late Cretaceous (Purilactis Group, sequence G) and Paleocene (sequence H) strata, and its empty space persisted through the Cenozoic. Eocene deformation caused long-wavelength rotation of a deeply weathered surface, generating an erosional unconformity across which coarse clastic strata accumulated (sequence J). Oligocene-early Miocene normal faulting, perhaps in a transtensional environment, repositioned the western basin margin and localized hangingwall subsidence, leading to the accumulation of thousands of meters of evaporitic strata (sequence K, Paciencia Group). By the close of the early Miocene, shortening resumed, first uplifting the intrabasinal Cordillera de la Sal and later generating Pliocene blind reverse faults within the topographically lowest part of the basin. Unequal deposition and tilting across the nascent Cordillera de la Sal induced diapirism of the Paciencia Group halite. In combination, inherited accommodation space and new tectonic subsidence, plus local salt-withdrawal subsidence, shaped the distribution of Upper Miocene-Recent ignimbrites, evaporites, and clastics (sequence M and Vilama

  8. A 22,000 14C year BP sediment and pollen record of climate change from Laguna Miscanti (23°S), northern Chile

    Science.gov (United States)

    Grosjean, M.; van Leeuwen, J. F. N.; van der Knaap, W. O.; Geyh, M. A.; Ammann, B.; Tanner, W.; Messerli, B.; Núñez, L. A.; Valero-Garcés, B. L.; Veit, H.

    2001-02-01

    Lake sediments and pollen, spores and algae from the high-elevation endorheic Laguna Miscanti (22°45'S, 67°45'W, 4140 m a.s.l., 13.5 km 2 water surface, 10 m deep) in the Atacama Desert of northern Chile provide information about abrupt and high amplitude changes in effective moisture. Although the lack of terrestrial organic macrofossils and the presence of a significant 14C reservoir effect make radiocarbon dating of lake sediments very difficult, we propose the following palaeoenvironmental history. An initial shallow freshwater lake (ca. 22,000 14C years BP) disappeared during the extremely dry conditions of the Last Glacial Maximum (LGM; 18,000 14C years BP). That section is devoid of pollen. The late-glacial lake transgression started around 12,000 14C years BP, peaked in two phases between ca. 11,000 and <9000 14C years BP, and terminated around 8000 14C years BP. Effective moisture increased more than three times compared to modern conditions (˜200 mm precipitation), and a relatively dense terrestrial vegetation was established. Very shallow hypersaline lacustrine conditions prevailed during the mid-Holocene until ca. 3600 14C years BP. However, numerous drying and wetting cycles suggest frequent changes in moisture, maybe even individual storms during the mid-Holocene. After several humid spells, modern conditions were reached at ca. 3000 14C years BP. Comparison between limnogeological data and pollen of terrestrial plants suggest century-scale response lags. Relatively constant concentrations of long-distance transported pollen from lowlands east of the Andes suggest similar atmospheric circulation patterns (mainly tropical summer rainfall) throughout the entire period of time. These findings compare favorably with other regional paleoenvironmental data.

  9. Isotopic evidence for divergent diets and mobility patterns in the Atacama Desert, northern Chile, during the Late Intermediate Period (AD 900-1450).

    Science.gov (United States)

    Santana-Sagredo, Francisca; Lee-Thorp, Julia A; Schulting, Rick; Uribe, Mauricio

    2015-03-01

    The decline of the Tiwanaku state saw the emergence of two new cultures-Pica-Tarapacá and Atacama-during the Late Intermediate Period in northern Chile. Archeological evidence suggests that both groups practised maize agriculture and pastoralism, but that their interaction zones differed significantly. Marine resources are common at Pica-Tarapacá sites, even those far from coast, while Atacama sites in the desert oases and precordilleran area seem to have directed their networks towards the highlands. Here we apply stable carbon, nitrogen, and oxygen isotope analysis on human bone and enamel to test dietary patterns and residential mobility at two sites, Pica 8 and Quitor 6, representing the Pica-Tarapacá and Atacama cultures, respectively. Our results show that diet at the two sites indeed differed: significant but variable consumption of marine resources and maize is indicated at Pica 8, despite being an inland site, while diet at Quitor 6 was based mainly on terrestrial resources. The use of seabird guano and llama dung as fertilizers and extreme aridity may have contributed to the high nitrogen isotope values observed in Pica 8 humans. The δ(18) O values in Pica 8 individuals are generally lower than for Quitor in spite of its greater distance from the Andes. All three isotopes suggest the presence of at least five nonlocals in the 30 measured at Pica 8. This evidence for human mobility is consistent with the high levels of trade and interaction observed in the archeological record, and begins to quantify the degree of movement of specific individuals. PMID:25385676

  10. Timing of Accretion and Mountain-Building in The Northern Andes of Colombia through Low-Temperature Thermochonology

    Science.gov (United States)

    Vinasco, C. J.; Restrepo-Moreno, S. A.; Marín, M. I.; Botero, M.; Bermudez, M. A.; Min, K. K.; Foster, D. A.; Noriega, S., Sr.; Montoya, E., Sr.; Londoño, L., Sr.; Bernet, M.

    2015-12-01

    Orogenic configuration of the Northern Andes is closely associated to accretional processes since the Upper Cretaceous. In Colombia, the regional boundary between a Paleozoic continental domain to the east and Cretaceous accreted terrenes to the west is well exposed in several E-W sections near Medellin City and along the Cauca River, which occupies a major depression located between the Central and Western cordilleras. The area is dominated by the N-S trending Romeral Fault System (RFS) that can be traced to southern Ecuador. Relationships between the RFS and W-SW verging thrust system are unknown, although they represent key components of a transpressional orogeny. To understand timing of accretion and associated mountain building processes, we performed (U-Th)/He and fission track dating on samples derived from vertical profiles in cordilleran massifs. Samples were collected along four vertical profiles on two distinct litho-tectonic units: (1) three vertical profiles in the older eastern realm corresponding to metamorphic basement rocks of the Paleozoic Paleo-continental margin and associated Cretaceous intrusives, and (2) one vertical profile in the Mande batholith, Eocene in age at the eastern portion of the Panama Chocó Block (PCB) . The resulting zircon (U-Th)/He (ZHe) ages show a clear contrast between the ancient eastern realm (~50-60 Ma) and the Mande Batholith (~30-40 Ma). Apatite (U-Th)/He (AHe) ages also show a strong contrast with 23-42 Ma for the eastern realm and a well defined cluster at ~4 Ma for the Mande Batholith. These preliminary results suggest distinctive cooling histories for the two litho-tectonic blocks. The Mande batholith (western block) records both the late Eocene and Pliocene events whereas the ancient eastern block does not preserve any of these events. The Paleocene events recorded by the eastern block are probably related to the Laramic orogenetic phase. Finally, elevation-invariable ZHe ages from the ancient eastern block

  11. Nurse effect in seedling establishment: facilitation and tolerance to damage in the Andes of central Chile Efecto nodriza en el establecimiento de plántulas: facilitación y tolerancia al daño en los Andes de Chile central

    Directory of Open Access Journals (Sweden)

    IAN S ACUÑA-RODRÍGUEZ

    2006-09-01

    Full Text Available Nurse effects, which occur when one plant species enhances the survival or growth of another plant species, are predicted to be most relevant in stressful environments. These effects are particulary important during seedling establishment due to their vulnerability to both biotic and abiotic factors, such as herbivory and drought. Tolerance to herbivory reflects the degree to which plants are able to regrow and reproduce after damage, and should vary with resource availability. In the high Andes of central Chile, the cushion plant Laretia acaulis (Apiaceae acts as a buffer against environmental stress, enhancing survival of several associated plant species. We hypothesized that tolerance to herbivory of seedlings growing inside the canopy of L. acaulis should be greater than that of seedlings growing outside the cushion plant. We conducted a field experiment to test this hypothesis for two native perennial species in the high Andes of central Chile: Hordeum comosum (Poaceae and Haplopappus anthylloides (Asteraceae. Seedlings of each species were planted inside and outside L. acaulis cushions and half of them received manual damage (50 % foliar tissue removed. Seedlings growing inside the nurse species showed high survival independent of the damage treatment. Whereas position (inside or outside the cushion plant did not affect tolerance of Haplopappus anthylloides, it significantly affected tolerance of Hordeum comosum. Thus, we found similar survival of damaged and control seedlings of H. comosum inside the cushions, but survival of damaged seedlings in the bare ground was lower than that of control seedlings. We verified the occurrence of nurse effects of Laretia acaulis on the establishment of both species, and detected enhancement of tolerance to damage in Hordeum comosum in this stressful habitatSe ha sugerido que el efecto nodriza, el cual se evidencia cuando una especie vegetal incrementa la supervivencia o el crecimiento de otra, es m

  12. Location and local magnitude of the Tocopilla earthquake sequence of Northern Chile

    Science.gov (United States)

    Fuenzalida, A.; Lancieri, M.; Madariaga, R. I.; Sobiesiak, M.

    2010-12-01

    The Northern Chile gap is generally considered to the site of the next megathurst event in Chile. The Tocopilla earthquake of 14 November 2007 (Mw 7.8) and aftershock series broke the southern end of this gap. The Tocopilla event ruptured a narrow strip of 120 km of length and a width that (Peyrat et al.; Delouis et al. 2009) estimated as 30 km. The aftershock sequence comprises five large thrust events with magnitude greater than 6. The main aftershock of Mw 6.7 occurred on November 15, at 15:06 (UTM) seawards of the Mejillones Peninsula. One month later, on December 16 2007, a strong (Mw 6.8) intraplate event with slab-push mechanism occurred near the bottom of the rupture zone. These events represent a unique opportunity for the study of earthquakes in Northern Chile because of the quantity and quality of available data. In the epicentral area, the IPOC network was deployed by GFZ, CNRS/INSU and DGF before the main event. This is a digital, continuously recording network, equipped with both strong-motion and broad-band instrument. On 29 November 2007 a second network named “Task Force” (TF) was deployed by GFZ to study the aftershocks. This is a dense network, installed near the Mejillones peninsula. It is composed by 20 short-period instruments. The slab-push event of 16 december 2007 occurred in the middle of the area covered by the TF network. Aftershocks were detected using an automatic procedure and manually revised in order to pick P and S arrivals. In the 14-28 November period, we detected 635 events recorded at the IPOC network; and a further 552 events were detected between 29 November and 16 December before the slab-push event using the TF network. The events were located using a vertically layered velocity model (Husen et al. 1999), using the NLLoc software of Lomax et al. From the broadband data we estimated the moment magnitude from the displacement spectra of the events. From the short-period instruments we evaluated local magnitudes using the

  13. The hot spring and geyser sinters of El Tatio, Northern Chile

    Science.gov (United States)

    Fernandez-Turiel, J. L.; Garcia-Valles, M.; Gimeno-Torrente, D.; Saavedra-Alonso, J.; Martinez-Manent, S.

    2005-10-01

    The siliceous sinter deposits of El Tatio geothermal field in northern Chile have been examined petrographically and mineralogically. These sinters consist of amorphous silica (opal-A) deposited around hot springs and geysers from nearly neutral, silica-saturated, sodium chloride waters. Water cooling and evaporation to dryness are the main processes that control the opal-A deposition in both subaqueous and subaerial settings, in close spatial relation to microbial communities. All fingerprints of organisms observed in the studied sinter samples represent microbes and suggest that the microbial community is moderately diverse (cyanobacteria, green bacteria, and diatoms). The most important ecological parameter is the temperature gradient, which is closely related to the observed depositional settings: 1) Geyser setting: water temperature = 70-86 °C (boiling point at El Tatio: 4200 m a.s.l.); coarse laminated sinter macrostructure with rapid local variations; biota comprises non-photosynthetic hyperthermophilic bacteria. 2) Splash areas around geysers: water temperature = 60-75 °C; laminated spicule and column macrostructure, locally forming cupolas (Tatio is a natural laboratory of great interest because the sedimentary macrostructures and microtextures reflect the geological and biological processes involved in the primary deposition and early diagenesis of siliceous sinters.

  14. Impact of empire expansion on household diet: the Inka in Northern Chile's Atacama Desert.

    Directory of Open Access Journals (Sweden)

    Sheila Dorsey Vinton

    Full Text Available The impact of expanding civilization on the health of American indigenous societies has long been studied. Most studies have focused on infections and malnutrition that occurred when less complex societies were incorporated into more complex civilizations. The details of dietary change, however, have rarely been explored. Using the analysis of starch residues recovered from coprolites, here we evaluate the dietary adaptations of indigenous farmers in northern Chile's Atacama Desert during the time that the Inka Empire incorporated these communities into their economic system. This system has been described as "complementarity" because it involves interaction and trade in goods produced at different Andean elevations. We find that as local farming societies adapted to this new asymmetric system, a portion of their labor had to be given up to the Inka elite through a corvée tax system for maize production. In return, the Inka system of complementarity introduced previously rare foods from the Andean highlands into local economies. These changes caused a disruption of traditional communities as they instituted a state-level economic system on local farmers. Combined with previously published infection information for the same populations under Inka rule, the data suggest that there may have been a dual health impact from disruption of nutrition and introduction of crowd disease.

  15. A new species of Ornithodoros (Acari: Argasidae) from desert areas of northern Chile.

    Science.gov (United States)

    Muñoz-Leal, Sebastián; Venzal, José M; González-Acuña, Daniel; Nava, Santiago; Lopes, Marcos G; Martins, Thiago F; Figueroa, Cecilia; Fernández, Nicolás; Labruna, Marcelo B

    2016-07-01

    Ornithodoros atacamensis n. sp. is described from larvae collected on the lizard Liolaemus bisignatus and from free-living adults collected in desert areas from the Pan de Azúcar and Llanos de Challe National Parks, in Northern Chile. Additionally, unengorged larvae were obtained from fertilized females, which laid eggs in the laboratory. Morphological and mitochondrial 16S rDNA sequence analyses were performed in order to compare this new soft tick species with other congeneric Neotropical representatives. Larvae of O. atacamensis are morphologically closely related to Ornithodoros talaje sensu stricto, Ornithodoros puertoricensis, Ornithodoros rioplatensis, Ornithodoros guaporensis and Ornithodoros hasei, all belonging to the O. talaje species group. The larval diagnostic characters for this species are a combination of a large pyriform dorsal plate with a length of approximately 300μm, 17 pairs of dorsal setae with five central pairs, hypostome with apex pointed and dental formula 2/2 in most rows, 3/3 apically, and capsule of the Haller's organ oval in shape without reticulations. Phylogenetic analyses inferred from the mitochondrial 16S rRNA gene and a Principal Component Analysis based on morphometric characters provide additional support to the description of O. atacamensis as an independent lineage within the genus clustering within the O. talaje species group. PMID:27132517

  16. Impact of empire expansion on household diet: the Inka in Northern Chile's Atacama Desert.

    Science.gov (United States)

    Vinton, Sheila Dorsey; Perry, Linda; Reinhard, Karl J; Santoro, Calogero M; Teixeira-Santos, Isabel

    2009-01-01

    The impact of expanding civilization on the health of American indigenous societies has long been studied. Most studies have focused on infections and malnutrition that occurred when less complex societies were incorporated into more complex civilizations. The details of dietary change, however, have rarely been explored. Using the analysis of starch residues recovered from coprolites, here we evaluate the dietary adaptations of indigenous farmers in northern Chile's Atacama Desert during the time that the Inka Empire incorporated these communities into their economic system. This system has been described as "complementarity" because it involves interaction and trade in goods produced at different Andean elevations. We find that as local farming societies adapted to this new asymmetric system, a portion of their labor had to be given up to the Inka elite through a corvée tax system for maize production. In return, the Inka system of complementarity introduced previously rare foods from the Andean highlands into local economies. These changes caused a disruption of traditional communities as they instituted a state-level economic system on local farmers. Combined with previously published infection information for the same populations under Inka rule, the data suggest that there may have been a dual health impact from disruption of nutrition and introduction of crowd disease. PMID:19956668

  17. August-September 2003 small vulcanian eruption at the Nevados de Chillán Volcanic Complex (36°50'S, Southern Andes (Chile

    Directory of Open Access Journals (Sweden)

    José A. Naranjo

    2004-12-01

    Full Text Available During the winter months of August-September 2003 a small (VEI=0-1 eruption took place at the 9 km long fissure-like Nevados de Chillán Volcanic Complex (36°50'S, that includes Nuevo (formed between 1906 and 1945 and Arrau (formed in the 1973-1986 period volcanoes. Only the local inhabitants and tourists of the ski resort located at the foothills noted the eruption. From August 29 to September 4, 2003, low-magnitude explosive events occurred and brown-greyish to white gas and ash columns reached up to 400 to 500 m above the crater, rising at periods that lasted for 20 to 25 minutes. After the first week, explosions became more sporadic and occurred at two-three day intervals. Strong prevailing winds from the north dispersed the low-altitude plume to the SSE until the eruption finally stopped by the middle of September. A new compound crater is now present in the saddle between Nuevo and Arrau volcanoes. This 64 m fissure-like double crater is surrounded by an area of intense fumaroles near to Nuevo volcano suggesting the renewal of activity in the complexPequeña erupción vulcaniana de agosto-septiembre en el Complejo Volcánco Nevados de Chillán (36°50'S, Andes del sur (Chile. Durante los meses invernales de agosto y septiembre de 2003 ocurrió una pequeña erupción (IEV=0-1 en la fisura de 9 km de largo del Complejo Volcánico Nevados de Chillán (36°50'S, que incluye a los volcanes Nuevo (formado entre 1906 y 1945 y Arrau (formado entre 1973 y 1986. La erupción fue advertida únicamente por los lugareños y los visitantes del centro invernal situado a los pies del volcán. La semana del 20 al 27 de agosto 2003 se produjeron eventos explosivos de baja magnitud con columnas de gas y ceniza de color pardo-grisáceo y blanco que alcanzaron alturas de 400 a 500 m con períodos de 20 a 25 minutos. Después de la primera semana las explosiones se hicieron más esporádicas ocurriendo a intervalos de 2 a 3 días. Los fuertes vientos

  18. A review of the non-bulimulid terrestrial Mollusca from the Region of Atacama, northern Chile

    Directory of Open Access Journals (Sweden)

    Juan Francisco Araya

    2014-04-01

    Full Text Available Terrestrial mollusca are sparsely studied in Chile and, for the first time, a formal record of the diversity of land snails in northern Chile is reported. Coastal and desertic areas in the Region of Atacama, in the border of the Atacama desert and the Pacific Ocean, were surveyed with the aim to describe the presence and distribution of this poorly known fauna. Of the fourteen species recorded, the geographic distribution records for nine species are extended, and some taxa are recorded for the first time since their original descriptions. All, except one, of the fourteen terrestrial molluscan species occurring in the area are endemic to Chile; they are all terrestrial species, most of them have a restricted geographic distribution, and none of them is currently protected by law. The results reveal that the region of Atacama has one of the most diverse terrestrial snail biodiversity in Chile, ranking only after the Juan Fernandez Archipelago. Distribution records of all the studied species and a taxonomic key are also provided.

  19. Latitudinal discontinuity in thermal conditions along the nearshore of central-northern Chile.

    Science.gov (United States)

    Tapia, Fabian J; Largier, John L; Castillo, Manuel; Wieters, Evie A; Navarrete, Sergio A

    2014-01-01

    Over the past decade, evidence of abrupt latitudinal changes in the dynamics, structure and genetic variability of intertidal and subtidal benthic communities along central-northern Chile has been found consistently at 30-32°S. Changes in the advective and thermal environment in nearshore waters have been inferred from ecological patterns, since analyses of in situ physical data have thus far been missing. Here we analyze a unique set of shoreline temperature data, gathered over 4-10 years at 15 sites between 28-35°S, and combine it with satellite-derived winds and sea surface temperatures to investigate the latitudinal transition in nearshore oceanographic conditions suggested by recent ecological studies. Our results show a marked transition in thermal conditions at 30-31°S, superimposed on a broad latitudinal trend, and small-scale structures associated with cape-and-bay topography. The seasonal cycle dominated temperature variability throughout the region, but its relative importance decreased abruptly south of 30-31°S, as variability at synoptic and intra-seasonal scales became more important. The response of shoreline temperatures to meridional wind stress also changed abruptly at the transition, leading to a sharp drop in the occurrence of low-temperature waters at northern sites, and a concurrent decrease in corticated algal biomass. Together, these results suggest a limitation of nitrate availability in nearshore waters north of the transition. The localized alongshore change results from the interaction of latitudinal trends (e.g., wind stress, surface warming, inertial period) with a major headland-bay system (Punta Lengua de Vaca at 30.25°S), which juxtaposes a southern stretch of coast characterized by upwelling with a northern stretch of coast characterized by warm surface waters and stratification. This transition likely generates a number of latitude-dependent controls on ecological processes in the nearshore that can explain species

  20. Parasite loads and altitudinal distribution of Liolaemus lizards in the central Chilean Andes Cargas parasitarias y distribución de lagartijas Liolaemus en los Andes de Chile central

    OpenAIRE

    JOHN H. CAROTHERS; Jaksic, Fabián M

    2001-01-01

    This study compared the distributions of ten species of Liolaemus lizards in the central Chilean Andes to the distributions of four types of parasites: malaria-causing Plasmodium, gut nematodes, ticks, and mites. We wanted to see if parasite numbers might be a factor in determining distributional limits of the lizards. We found that there was no evidence of malarial infestation of the lizards, that ticks were almost absent, that more often than not mite numbers decreased at the distributional...

  1. Salar de Atacama basin: A record of compressional tectonics in the central Andes since the mid-Cretaceous

    Science.gov (United States)

    Arriagada, Cesar; Cobbold, Peter R.; Roperch, Pierrick

    2006-02-01

    The Salar de Atacama basin lies in the inner fore arc of northern Chile. Topographically and structurally, it is a first-order feature of the central Andes. The sedimentary fill of the basin constrains the timing and extent of crustal deformation since the mid-Cretaceous. We have studied good exposures along the western edge of the basin and have correlated them with seismic reflection sections and data from an exploration well. Throughout most of its history, the basin developed in a foreland setting, during periods of thin-skinned and thick-skinned thrusting. Growth strata provide evidence for coeval sedimentation and thrust motions during mid-Cretaceous, Paleogene, and Neogene times. Pre-Neogene deformation was significant in the basin and in surounding areas of the early central Andes. Models that attempt to explain the current thickness of the central Andes should consider Late Cretaceous and Paleogene shortening, as well as the more obvious Neogene and Quaternary shortening.

  2. 800,000-Year Record of Plate Boundary Earthquakes in the Atacama Desert, Northern Chile

    Science.gov (United States)

    Baker, A. M.; Owen, L. A.; Rech, J.; Allmendinger, R. W.

    2010-12-01

    Coseismic cracks preserved in the hyper-arid Atacama Desert of Northern Chile provide a unique record of the seismic history of the modern Andean forearc, which has generated the largest earthquakes on earth. Loveless et al. (2009) mapped more than 50,000 cracks on satellite imagery and, based on boundary element modeling, suggested that they indicate repeated rupture of approximately the same segment. But, what is the time frame of the repeated rupture and what is the long-term strain rate of the forearc due to this process? West of Salar Grande, five overlapping fan surfaces contain different densities of coseismic cracks, allowing for such an assessment. The fan surfaces are highly indurated with gypsum and salt, resulting in excellent preservation of these brittle features. All surfaces are underlain by a tuff ~4 m.y. old. Older surfaces consistently have more and larger cracks than younger surfaces. Locally, cracks cutting across multiple surfaces have distinctly different widths and morphologies. Density is the number of cracks present per given length and total opening is the sum of the widths along that same length. Both crack density and total opening on each surface show a positive relationship to relative age, supporting the previously anecdotal evidence for reactivation of cracks through time with multiple events. Fresh, centimeter-scale cracks are also present on all surfaces, further supporting that these features record a history rather than a singular event. Three of the five fan surfaces have sufficiently large quartz clasts for exposure dating using 10Be and 26Al, providing absolute ages to use in calculating strain rate due to cracking. The oldest surface is 800±100 ky old. Samples from active channels constrain inheritance of cosmogenic nuclides, and nuclide ratios suggest no significant burial. Strain rates calculated from total opening and surface age range from 1.3x10^-15s^-1 to 2.4x10^-15s^-1 across the three surfaces. For comparison, we

  3. Generation of a mixture model ground-motion prediction equation for Northern Chile

    Science.gov (United States)

    Haendel, A.; Kuehn, N. M.; Scherbaum, F.

    2012-12-01

    observed ground motion data in the region of interest) is then transferring information from other regions to the region where the observations have been produced in a data driven way. The backbone model is learned by comparing the model predictions to observations of the target region. For each observation and each model, the likelihood of an observation given a certain GMPE is calculated. Mixture weights can then be assigned using the expectation maximization (EM) algorithm or Bayesian inference. The new method is used to generate a backbone reference model for Northern Chile, an area for which no dedicated GMPE exists. Strong motion recordings from the target area are used to learn the backbone model from a set of 10 GMPEs developed for different subduction zones of the world. The formation of mixture models is done individually for interface and intraslab type events. The ability of the resulting backbone models to describe ground motions in Northern Chile is then compared to the predictive performance of their constituent models.

  4. Evaporation and land surface energy budget at the Salar de Atacama, Northern Chile

    Science.gov (United States)

    Kampf, Stephanie K.; Tyler, Scott W.; Ortiz, Cristián A.; Muñoz, José F.; Adkins, Paula L.

    2005-08-01

    Playa systems are driven by evaporation processes, yet the mechanisms by which evaporation occurs through playa salt crusts are still poorly understood. In this study we examine playa evaporation as it relates to land surface energy fluxes, salt crust characteristics, groundwater and climate at the Salar de Atacama, a 3000 km 2 playa in northern Chile containing a uniquely broad range of salt crust types. Land surface energy budget measurements were taken at eight representative sites on this playa during winter (August 2001) and summer (January 2002) seasons. Measured values of net all-wave radiation were highest at vegetated and rough halite crust sites and lowest over smooth, highly reflective salt crusts. Over most of the Salar de Atacama, net radiation was dissipated by means of soil and sensible heat fluxes. Dry salt crusts tended to heat and cool very quickly, whereas soil heating and cooling occurred more gradually at wetter vegetated sites. Sensible heating was strongly linked to wind patterns, with highest sensible heat fluxes occurring on summer days with strong afternoon winds. Very little energy available at the land surface was used to evaporate water. Eddy covariance measurements could only constrain evaporation rates to within 0.1 mm d -1, and some measured evaporation rates were less than this margin of uncertainty. Evaporation rates ranged from 0.1 to 1.1 mm d -1 in smooth salt crusts around the margin of the salar and from 0.4 to 2.8 mm d -1 in vegetated areas. No evaporation was detected from the rugged halite salt crust that covers the interior of the salar, though the depth to groundwater is less than 1 m in this area. These crusts therefore represent a previously unrecorded end member condition in which the salt crusts form a practically impermeable barrier to evaporation.

  5. Slip distribution of the 2014 Iquique earthquake in northern Chile derived from tsunami waveform inversion

    Science.gov (United States)

    Baba, T.; Takagawa, T.; Tsushima, H.; Hayashi, Y.; Tomita, T.; Gómez, C.; Catalan, P. A.

    2014-12-01

    A major earthquake occurred on the plate boundary between the Nazca plate and the South American plate on April 1, 2014 in northern Chile associated with a tsunami that was recorded at the offshore DART buoys and the coastal tide gauges. The epicenter was located in a seismic gap called "Iquique gap", but the moment magnitude was estimated to be 8.2 from the seismic wave analysis which was much smaller than the size of seismic gap. It is important to reveal the slip distribution of this earthquake in order to assess remaining tsunami risk in the region. We therefore carried out a tsunami inversion analysis for this earthquake. We used tsunami waveform data recorded at both of the offshore and coastal gauges, and 30 arc-sec interval bathymetric grid complied by the Hydrographic and Oceanographic Service of the Chilean Navy. We also examined effect of tsunami governing equations used in creating Green's functions. One solution was obtained with the linear long-wave equations; the other was obtained with the linear dispersive equations. The effect of dispersive equations was found in tsunami waveforms in the open ocean. But that was not apparent in near-field records and the estimated slip distribution itself. The observed tsunami waveforms were retrieved well in the analysis except at Tocopilla where a large delay of tsunami arrival of about 10 minutes was seen in the observed data. Features of the estimated slip are 1) the slip extent was approximately 120km x 80km, 2) the major slip area was located to the south of the epicenter, a region off between Pisagua and Iquique, 3) the maximum slip was about 5m, 4) the seismic moment was calculated to be 1.28x10^21Nm (Mw 8.0).

  6. Spectral scaling of the aftershocks of the Tocopilla 2007 earthquake in northern Chile

    Science.gov (United States)

    Lancieri, M.; Madariaga, R.; Bonilla, F.

    2012-04-01

    We study the scaling of spectral properties of a set of 68 aftershocks of the 2007 November 14 Tocopilla (M 7.8) earthquake in northern Chile. These are all subduction events with similar reverse faulting focal mechanism that were recorded by a homogenous network of continuously recording strong motion instruments. The seismic moment and the corner frequency are obtained assuming that the aftershocks satisfy an inverse omega-square spectral decay; radiated energy is computed integrating the square velocity spectrum corrected for attenuation at high frequencies and for the finite bandwidth effect. Using a graphical approach, we test the scaling of seismic spectrum, and the scale invariance of the apparent stress drop with the earthquake size. To test whether the Tocopilla aftershocks scale with a single parameter, we introduce a non-dimensional number, ?, that should be constant if earthquakes are self-similar. For the Tocopilla aftershocks, Cr varies by a factor of 2. More interestingly, Cr for the aftershocks is close to 2, the value that is expected for events that are approximately modelled by a circular crack. Thus, in spite of obvious differences in waveforms, the aftershocks of the Tocopilla earthquake are self-similar. The main shock is different because its records contain large near-field waves. Finally, we investigate the scaling of energy release rate, Gc, with the slip. We estimated Gc from our previous estimates of the source parameters, assuming a simple circular crack model. We find that Gc values scale with the slip, and are in good agreement with those found by Abercrombie and Rice for the Northridge aftershocks.

  7. Long-term persistence of subduction earthquake segment boundaries: Evidence from Mejillones Peninsula, northern Chile

    Science.gov (United States)

    Victor, P.; Sobiesiak, M.; Glodny, J.; Nielsen, S. N.; Oncken, O.

    2011-02-01

    The Mejillones Peninsula in northern Chile has been recognized as the surface expression of a segment boundary for large subduction zone earthquakes. The sharp contact between the rupture planes of two instrumentally recorded earthquakes, the Mw = 8.0 Antofagasta (1995) and the Mw = 7.7 Tocopilla (2007) events, is located beneath the central part of Mejillones Peninsula. We present new chronostratigraphic and structural data that allow reconstructing the evolution of the Peninsula at the surface and correlation of the latter with seismic cycle deformation on the plate interface. Uplift commenced after 3.4 Myr, as recorded in the western highland. The central graben area on the Peninsula started uplifting above sea level as an anticlinal hinge zone prior to 400 kyr ago, most probably 790 kyr ago. The resulting E-W trending hinge exactly overlies the limit between the rupture planes of the Antofagasta and Tocopilla earthquakes. By correlating the uplift data with the slip distribution of the above earthquakes, we demonstrate that deformation and uplift is focused during the postseismic and interseismic periods of the megathrust seismic cycle with coseismic deformation opposed to the long-term motion. Additionally, the slip deficit beneath the Peninsula accumulating between events is probably largely recovered by creep. Hence we suggest that Mejillones Peninsula owes its existence to the lateral variation of the propensity for unstable slip at the interface. Since the latter is a material property, the long-term spatial stability of the Peninsula as a barrier to rupture propagation since at least the middle Pleistocene is a necessary consequence.

  8. A new species of Eccopsis Zeller (Lepidoptera, Tortricidae from the coastal valleys of northern Chile, with the first continental record of E. galapagana Razowski & Landry

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    Héctor A. Vargas

    2011-06-01

    Full Text Available A new species of Eccopsis Zeller (Lepidoptera, Tortricidae from the coastal valleys of northern Chile, with the first continental record of E. galapagana Razowski & Landry. Eccopsis Zeller, 1852 is reported for the first time from Chile. Eccopsis razowskii Vargas, n. sp. is described and illustrated based on specimens reared from larvae collected on native Acacia macracantha Willd. (Fabaceae in the coastal valleys of the northern Chilean desert. Eccopsis galapagana Razowski & Landry, 2008, previously known only from the Galapagos Islands, Ecuador, is recorded for the first time from continental South America. Larvae of the latter were collected in northern Chile feeding on Prosopis alba Griseb (Fabaceae.Uma nova espécie de Eccopsis Zeller (Lepidoptera, Tortricidae dos valles litorais do norte do Chile, e o primeiro registro continental de E. galapagana Razowski & Landry. Eccopsis Zeller (Lepidoptera, Tortricidae é registrado pela primeira vez para o Chile. Eccopsis razowskii Vargas, n. sp. é descrita e ilustrada com base em espécimes criados de larvas colectadas em Acacia macracantha Willd. (Fabaceae nos vales litorais do deserto do norte do Chile. Eccopsis galapagana Razowski & Landry, 2008, conhecida previamente das Ilhas Galápados, Equador, é registrada pela primeira vez para SulAmérica continental. Suas larvas foram coletadas em Prosopis alba Griseb (Fabaceae.

  9. Diel variation in the vertical distribution of fish larvae forced by upwelling filaments off Punta Angamos (northern Chile)

    OpenAIRE

    Pablo M Rojas

    2014-01-01

    The role of daily vertical migration (DVM) of ichthyoplanktonic associations off Punta Angamos, in northern Chile, was examined. In September 1998 and January 1999, two oceanographic surveys were conducted during coastal upwelling events. Fish larvae were collected during the day/night in three depth strata (0-20, 20-80 and 80-200 m) and inside/outside of upwelling filaments. The study area was dominated by a southward flow along 200 m depth; meanwhile, the Ekman layer did not exceed 20 m dep...

  10. Detrital Zircon Provenance Record of Pre-Andean to Modern Tectonics in the Northern Andes: Examples from Peru, Ecuador, and Colombia

    Science.gov (United States)

    George, S. W. M.; Jackson, L. J.; Horton, B. K.

    2015-12-01

    Detrital zircon U-Pb age distributions from modern rivers and Mesozoic-Cenozoic basin fill in the northern Andes provide insights into pre-Andean, Andean, and active uplift and exhumation of distinctive sediment source regions. Diagnostic age signatures enable straightforward discrimination of competing sediment sources within the Andean magmatic arc (Western Cordillera-Central Cordillera), retroarc fold-thrust belt (Eastern Cordillera-Subandean Zone), and Amazonian craton (composed of several basement provinces). More complex, however, are the mid/late Cenozoic provenance records generated by recycling of basin fill originally deposited during early/mid Mesozoic extension, late Mesozoic thermal subsidence, and early Cenozoic shortening. Although subject to time-transgressive trends, regionally significant provenance patterns in Peru, Ecuador, and Colombia reveal: (1) Triassic-Jurassic growth of extensional subbasins fed by local block uplifts (with commonly unimodal 300­-150 Ma age peaks); (2) Cretaceous deposition in an extensive postrift setting fed by principally cratonic sources (with common 1800-900 Ma ages); and (3) Cenozoic growth of a broad flexural basin fed initially fed by magmatic-arc rocks (100-0 Ma), then later dominance by thrust-belt sedimentary rocks with progressively greater degrees of basin recycling (yielding diverse and variable age populations from the aforementioned source regions). U-Pb results from modern rivers and smaller subbasins prove useful in evaluating source-to-sink relationships, downstream mixing relationships, hinterland-foreland basin connectivity, paleodrainage integration, and tectonic/paleotopographic reconstructions. Most but not all of the elevated intermontane basins in the modern hinterland of the northern Andes contain provenance records consistent with genesis in a broader foreland basin developed at low elevation. Downstream variations within modern axial rivers and Cenozoic axial basins inform predictive models of

  11. Glacier meltwater flow paths and storage in a geomorphologically complex glacial foreland: The case of the Tapado glacier, dry Andes of Chile (30°S)

    Science.gov (United States)

    Pourrier, J.; Jourde, H.; Kinnard, C.; Gascoin, S.; Monnier, S.

    2014-11-01

    The Tapado catchment is located in the upper Elqui river basin (4000-5550 m) in northern Chile. It comprises the Tapado glacial complex, which is an assemblage of the Tapado glacier and the glacial foreland (debris-covered glacier, rock glacier, and moraines). Although the hydrological functioning of this catchment is poorly known, it is assumed to actively supply water to the lower semi-arid areas of the Elqui river basin. To improve our knowledge of the interactions and water transfers between the cryospheric compartment (glacier, debris-covered glacier, and rock glacier) and the hydrological compartment (aquifers, streams), the results of monitoring of meteorological conditions, as well as discharge, conductivity and temperature of streams and springs located in the Tapado catchment were analyzed. The hydrological results are compared to results inferred from a ground penetrating radar (GPR) survey of the underground structure of the glacial foreland. Water production from the Tapado glacier was shown to be highly correlated with daily and monthly weather conditions, particularly solar radiation and temperature. The resulting daily and monthly streamflow cycles were buffered by the glacial foreland, where underground transfers took place through complex flow paths. However, the development of a thermokarst drainage network in a portion of the glacial foreland enabled rapid concentrated water transfers that reduced the buffer effect. The glacial foreland was shown to act as a reservoir, storing water during high melt periods and supplying water to downstream compartments during low melt periods. GPR observations revealed the heterogeneity of the internal structure of the glacial foreland, which is composed of a mixture of ice and rock debris mixture, with variable spatial ice content, including massive ice lenses. This heterogeneity may explain the abovementioned hydrological behaviors. Finally, calculation of a partial hydrological budget confirmed the

  12. Dasybasis elquiensis, a new species of horse fly from Northern Chile (Diptera: Tabanidae: Diachlorini

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    González Christian R

    2000-01-01

    Full Text Available The female of Dasybasis elquiensis, new species, is described and illustrated from specimens collected in Paso La Ternera, Elqui Province, north Chile. Its relationships to other Dasybasis species are discussed.

  13. A study of SO2 emissions and ground surface displacements at Lastarria volcano, Antofagasta Region, Northern Chile

    Science.gov (United States)

    Krewcun, Lucie G.

    Lastarria volcano (Chile) is located at the North-West margin of the 'Lazufre' ground inflation signal (37x45 km2), constantly uplifting at a rate of ˜2.5 cm/year since 1996 (Pritchard and Simons 2002; Froger et al. 2007). The Lastarria volcano has the double interest to be superimposed on a second, smaller-scale inflation signal and to be the only degassing area of the Lazufre signal. In this project, we compared daily SO2 burdens recorded by AURA's OMI mission for 2005-2010 with Ground Surface Displacements (GSD) calculated from the Advanced Synthetic Aperture Radar (ASAR) images for 2003-2010. We found a constant maximum displacement rate of 2.44 cm/year for the period 2003-2007 and 0.80- 0.95 cm/year for the period 2007-2010. Total SO 2 emitted is 67.0 kT for the period 2005-2010, but detection of weak SO2 degassing signals in the Andes remains challenging owing to increased noise in the South Atlantic radiation Anomaly region.

  14. Identificación de Hantavirus Andes en Rattus norvegicus Identification of Andes Hantavirus in Rattus norvegicus

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    J Fernández

    2008-01-01

    Full Text Available En Chile y Argentina la especie Oligoryzomys longicaudatus ha sido identificada como el principal reservorio para Virus Andes (ANDV. El objetivo de este trabajo es reportar la presencia del virus Andes en Rattus norvergicus, roedor urbano recolectado de un muestreo en San Diego del Cristo, comuna de Melipilla, Región Metropolitana. La presencia del virus Andes en Rattus norvegicus podría indicar la importancia de otros roedores como eventuales vectores virales.In Chile and Argentina Oligoryzomys longicaudatus has been identified as the main reservoir for Hantavirus Andes. The aim of this work was to report the presence of Hantavirus Andes in Rattus norvegicus, an urban rodent collected during sampling in San Diego del Cristo, Melipilla, Metropolitan Region. The existence of Hantavirus Andes in Rattus norvegicus could indicate the importance of other rodents as possible viral vectors.

  15. The Early Andean Magmatic Province (EAMP): Ar-40/Ar-39 dating on mesozoic volcanic and plutonic rocks from the Coastal Cordillera, northern Chile

    OpenAIRE

    Oliveros, V.; Féraud, G.; L. Aguirre; Fornari, Michel; D. Morata

    2006-01-01

    The Early Andean Magmatic Province (EAMP), consists of about 150000 km(3) of volcanic and platonic units in the Coastal Cordillera of northern Chile and southern Peru and represents a major magmatic Mesozoic event in the world, for which the precise age of the thick volcanic series was unknown. Thirty Ar-40/Ar-39 analyses were carried out on primary mineral phases of volcanic and plutonic rocks from northern Chile (18 degrees 30'-24 degrees S). Reliable plateau and "mini plateau" ages were ob...

  16. Distribution of prokaryotic genetic diversity in athalassohaline lakes of the Atacama Desert, Northern Chile.

    Science.gov (United States)

    Demergasso, Cecilia; Casamayor, Emilio O; Chong, Guillermo; Galleguillos, Pedro; Escudero, Lorena; Pedrós-Alió, Carlos

    2004-04-01

    Athalassohaline lakes are inland saline aquatic environments with ionic proportions quite different from the dissolved salts in seawater. Prokaryotes inhabiting athalassohaline environments are poorly known and very few of such places have been surveyed for microbial diversity studies around the world. We analyzed the planktonic bacterial and archaeal assemblages inhabiting several of these evaporitic basins in a remote and vast area in northern Chile by PCR-denaturing gradient gel electrophoresis (DGGE) and sequencing of 16S rRNA gene fragments. Most systems were springs and athalassohaline ponds in different saltflats of the Atacama Desert region, including Salar de Llamará (in the Central Depression), Salar de Atacama (in the Pre-Andean Depression) and Salar de Ascotán (in the Altiplano). Overall, we analyzed more than 25 samples from 19 different environments with strong gradients of altitude, qualitative ionic compositions and UV influence. Between 4 and 25 well-defined DGGE bands were detected for Bacteria in each sample, whereas Archaea ranged between 1 and 5. Predominant DGGE bands (defined by intensity and frequency of appearance) were excised from the gel and sequenced. Bacterial assemblages were dominated by the Cytophaga-Flavobacterium-Bacteroides (CFB) phylum and a few Proteobacteria. There was a tendency for increasing contribution of CFB with higher salinities and altitude. Thus, CFB accounted for the major fraction of band intensity in the Ascotán samples and for lower percentages in Atacama and Llamará. When the distribution of particular CFB sequences was examined, there were several relatives of Psychroflexus torquis substituting each other as salinity changed in Ascotán. Another set of CFB sequences, very distantly related to Cytophaga marinovorus, was abundant in both Llamará and Atacama at salinities lower than 7%. Archaeal assemblages were dominated by uncultured haloarchaea distantly related to cultured strains mostly obtained from

  17. A 22,000-year record of monsoonal precipitation from northern Chile's Atacama Desert

    Science.gov (United States)

    Betancourt, J.L.; Latorre, C.; Rech, J.A.; Quade, Jay; Rylander, K.A.

    2000-01-01

    Fossil rodent middens and wetland deposits from the central Atacama Desert (22° to 24°S) indicate increasing summer precipitation, grass cover, and groundwater levels from 16.2 to 10.5 calendar kiloyears before present (ky B.P.). Higher elevation shrubs and summer-flowering grasses expanded downslope across what is now the edge of Absolute Desert, a broad expanse now largely devoid of rainfall and vegetation. Paradoxically, this pluvial period coincided with the summer insolation minimum and reduced adiabatic heating over the central Andes. Summer precipitation over the central Andes and central Atacama may depend on remote teleconnections between seasonal insolation forcing in both hemispheres, the Asian monsoon, and Pacific sea surface temperature gradients. A less pronounced episode of higher groundwater levels in the central Atacama from 8 to 3 ky B.P. conflicts with an extreme lowstand of Lake Titicaca, indicating either different climatic forcing or different response times and sensitivities to climatic change.

  18. Shallow water heterobranch sea slugs (Gastropoda: Heterobranchia) from the Región de Atacama, northern Chile.

    Science.gov (United States)

    Araya, Juan Francisco; Valdés, Ángel

    2016-01-01

    The coast of northern Chile has been sparsely studied in regards to its invertebrate fauna, with just a few works reviewing the distribution of local mollusks. This work presents a survey of the shallow water heterobranch sea slugs currently occurring around the port of Caldera (27 °S), in the Región de Atacama, northern Chile. Eight species of sea slugs were found in this study: Aplysiopsis cf. brattstroemi (Marcus, 1959), Baptodoris peruviana (d'Orbigny, 1837), Diaulula variolata (d'Orbigny, 1837), Doris fontainii d'Orbigny, 1837, Onchidella marginata (Couthouy in Gould, 1852), Phidiana lottini (Lesson, 1831), Tyrinna delicata (Abraham, 1877) and the new species Berthella schroedli sp. nov., described herein. All of the species found in the area are endemic to South America, having distributions in the southeastern Pacific and South Atlantic Oceans, from Ancash, Perú to Peninsula Valdés, Argentina, and two of them represent species which are endemic to the Chilean coasts (Aplysiopsis cf. brattstroemi and Berthella schroedli). The finding of a previously undescribed species emphasizes the need of further surveys, particularly in subtidal and deeper waters, in order to improve the knowledge on this neglected fauna in Atacama. PMID:27168975

  19. Shallow water heterobranch sea slugs (Gastropoda: Heterobranchia) from the Región de Atacama, northern Chile

    Science.gov (United States)

    Valdés, Ángel

    2016-01-01

    The coast of northern Chile has been sparsely studied in regards to its invertebrate fauna, with just a few works reviewing the distribution of local mollusks. This work presents a survey of the shallow water heterobranch sea slugs currently occurring around the port of Caldera (27 °S), in the Región de Atacama, northern Chile. Eight species of sea slugs were found in this study: Aplysiopsis cf. brattstroemi (Marcus, 1959), Baptodoris peruviana (d’Orbigny, 1837), Diaulula variolata (d’Orbigny, 1837), Doris fontainii d’Orbigny, 1837, Onchidella marginata (Couthouy in Gould, 1852), Phidiana lottini (Lesson, 1831), Tyrinna delicata (Abraham, 1877) and the new species Berthella schroedli sp. nov., described herein. All of the species found in the area are endemic to South America, having distributions in the southeastern Pacific and South Atlantic Oceans, from Ancash, Perú to Peninsula Valdés, Argentina, and two of them represent species which are endemic to the Chilean coasts (Aplysiopsis cf. brattstroemi and Berthella schroedli). The finding of a previously undescribed species emphasizes the need of further surveys, particularly in subtidal and deeper waters, in order to improve the knowledge on this neglected fauna in Atacama.

  20. Weathering and solute transport to the Salar de Atacama, northern Chile

    Science.gov (United States)

    Hynek, S. A.; Munk, L. A.; Boutt, D. F.

    2013-12-01

    The Salar de Atacama is situated in a tectonic basin on the Tropic of Capricorn, adjacent to the Central Andean Volcanic Zone in hyper-arid northern Chile. This basin has been hydrographically closed for most, if not all, of the Cenozoic. Since the late Miocene, chemical sediment (primarily halite, but also sulphate) and Na-Cl brines have accumulated. The volume of these deposits provides a constraint on long term average solute fluxes. We have undertaken an extensive multiple isotope study of surface and shallow groundwater in the basin to constrain processes and pathways affecting solute fluxes to the basin. By comparing these inflow waters to brackish waters and brines, we are able to place constraints on modern weathering with the ultimate goal of comparing it to longer term fluxes estimated from the geologic record. The volcanic arc and extensive large volume silicic magma chambers provide potential sources of solutes to the basin which are not a direct result of surficial weathering (hydrothermal waters/magmatic brines). For most freshwater, this possibility is ruled out. Oxygen and hydrogen isotopes in water provide no strong evidence for high temperature water-rock interaction. Further, the isotopic composition of helium dissolved in groundwater demonstrates that most groundwater carries an atmospheric signal (air saturated water), though some evidence for the influence of magmatic brines is found in shallow groundwater with high concentrations of helium-3, methane, and carbon dioxide. The strontium isotopic composition of waters and brines exhibits geographic variation that is related to at least four sources; 1) weathering of Andean volcanic arc along the eastern margin of the basin (87/86 ratios ~0.708), 2) thermal waters sourced in the northern headwaters of the Río San Pedro and 3) high calcium weathering fluxes from the Cordón de Lila on the southern margin of the basin, both of which have more radiogenic 87/86 ratios than the Andean volcanic arc

  1. Reestablecimiento de Choromytilus chorus (Molina, 1782 (Bivalvia: Mytilidae en el norte de Chile Reestablishment of Choromytilus chorus (Molina, 1782 (Bivalvia: Mytilidae in northern Chile

    Directory of Open Access Journals (Sweden)

    Miguel Avendaño

    2011-07-01

    Full Text Available Hasta fines del siglo pasado no existían registros de la presencia de Choromytilus chorus al norte de los 23°S, pese a antecedentes que señalaban su existencia en épocas pasadas. Ciertos cambios relacionados con las masas de agua costeras de esta zona, habrían generado la ausencia o escasez que presentaba el entorno costero actual. Sin embargo, hace una década atrás, su presencia en el norte de Chile, comienza a tener connotación pesquera. En el presente trabajo se confirma su reestablecimiento en las regiones de Antofagasta y Tarapacá, mediante prospecciones realizadas en seis lugares donde se registró su presencia, así como mediante la captación de semilla en colectores suspendidos. Se indica interacción con Aulacomya ater, a la cual ha desplazado a estratos más profundos, mientras que su reestablecimiento, iniciado en las regiones de Atacama y Antofagasta, y que se amplió posteriormente a la región de Tarapacá; permite postular la hipótesis que la dinámica de estos bancos, respondería a una estructura de metapoblación, dado el sistema de corrientes y vientos que predominan en la zona norte, permitiendo la advección larval de poblaciones existentes en la región de Coquimbo.Despite indications of its presence in past ages, until the end of the last century, no records showed Choromytilus chorus north of 23°S. Certain changes related to coastal water masses in the zone could be responsible for the present lack or scarcity of this species in the coastal area. However, a decade ago, this species appeared in northern Chile in the context of fisheries. This study confirms the re-establishment of C. chorus in the Antofagasta and Tarapaca regions through surveys at six sites where the species had been registered and spat collection using suspended collectors. This species has interacted with Aulacomya ater, displacing it towards deeper habitats. The re-establishment of C. chorus began in the Atacama and Antofagasta regions and

  2. Combining point and distributed snowpack data with landscape-based discretization for hydrologic modeling of the snow-dominated Maipo River Basin, in the semi-arid Andes central Chile

    Science.gov (United States)

    Videla Giering, Y. A., III; McPhee, J. P.

    2015-12-01

    Snow hydrology in mountain environments plays an important role in the availability of hydrological resources in warm climate areas and height effects, since the magnitude of snowpack, its spatial and temporal distribution is very important to determine the availability of water in the snowmelt season and take forward different productive activities This investigation models and assess the main phenomena hydrological cycle of snow using the software Cold Region Hydrological Model (Pomeroy et al., 2007). The software is a physically based model developed by the centre for hydrology, University of Saskatchewan. The aim of this model is to have a better understanding of hydrological processes involved in cold environments, which are particular in the sense that a host of specific phenomena such as snow and ice accumulation, transport and melt, infiltration through frozen soils, and the like, control the hydrograph timing) The analysis involved the development of a hydrologic model for the Upper Maipo River Basin, with elevations between 800 and 6500 meters above sea level and 5000-km^2 watershed in the Andes of Central Chile which supplies water resources to the capital city of Santiago (7 million inhabitants), to a thriving agricultural region, as well as to hydropower and large mining activities. The paper concludes that there is a differential distribution of snow cover in the study area, determined mainly by steep terrain geomorphology. These factors have been considered in the parameterization of the model, showing considerable variation in storage time, redistributions by blowing snow, melting intervals, infiltration rates and drainage basin. The fictional scenarios modeled demonstrate noticeable changes in the hydrograph, showing the fragile climate and hydrological condition of this basin of Central Chile.

  3. Incomplete trimorphic incompatibility expression in Oxalis compacta Gill. ex Hook. et Arn. subsp. compacta in the central Chilean Andes Expresión incompleta de incompatibilidad trimórfica en Oxalis compacta Gill. ex Hook. et Arn. subsp. compacta en los Andes de Chile central

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    MARY T. K ARROYO

    2012-01-01

    Full Text Available The expression of trimorphic incompatibility was investigated in a high altitude population of Oxalis compacta subsp. compacta distributed in the upper alpine belt (3100-3470 m of the central Chile Andes. Stigma-anther reciprocity (2 populations, morph representation (7 populations, unassisted selfing capacity and open-pollination fruit set (6 populations were determined. O. compacta ssp. compacta es highly dependent on external pollinators. Although it has typical tristylous flowers, considerable seed set is possible following illegitimate intermorph and intramorph cross pollination. Open pollination fruit set varied from 9-83% and on average was lower in the higher-elevation populations. The possibility of seed set following two kinds of illegitimate cross pollination is seen as a means of enhancing reproductive output by enabling more effective use of the limited pollinator resource in the high alpine environment, where fruit set shows high inter-annual variability and there is some evidence for pollination limitation in Oxalis compacta subsp. compacta.Se investigó la expresión de incompatibilidad trimórfica en una población de Oxalis compacta subsp. compacta distribuida en la zona alpina superior de los Andes de Chile central. Se determinó la reciprocidad de los estigmas y anteras (dos poblaciones, representación de morfos florales (7 poblaciones, capacidad para autofecundación no asistida y polinización abierta (6 poblaciones. O. compacta subsp. compacta es altamente dependiente de polinizadores externos. No obstante la presencia de flores tristilicas, las dos categorías ilegítimas de polinización dieron semillas. La producción de frutos mediante polinización abierta fluctuó entre 9-83% y en promedio fue menor en las poblaciones de mayor elevación. Se plantea que la capacidad de formar semillas mediante polinización ilegítima permitirá el uso más eficaz del recurso limitado de polinización en la zona andina superior

  4. Oxygenation variability in Mejillones Bay, off northern Chile, during the last two centuries

    NARCIS (Netherlands)

    Diaz-Ochoa, J.A.; Pantoja, S.; de Lange, G.J.; Lange, C.B.; Sanchez, G.E.; Acuna, V.R.; Munoz, P.; Vargas, G.

    2011-01-01

    The Peru Chile Current ecosystem is characterized by high biological productivity and important fisheries. Although this system is likely to be severely affected by climate change, its response to current global warming is still uncertain. In this paper, we analyze 10–166 year-old sediments in two c

  5. The 14 November, 2007 Mw 7.8 Tocopilla, northern Chile earthquake within the Iquique seismic gap

    Science.gov (United States)

    Schurr, B.; Motagh, M.; Krüger, F.; Asch, G.; Anderssohn, J.; Sobiesiak, M.; Kind, R.; Sodoudi, F.; Ohrnberger, M.; Chong Díaz, G.; Vilotte, J.; Oncken, O.

    2008-05-01

    A prominent seismic gap persisted in northern Chile between the towns of Antofagasta and Arica for 130 years. This 500 km segment along the South American subduction zone last ruptured in 1877 in a devastating M9 earthquake. On November 14th 2007, an Mw 7.8 earthquake started near the coastal town of Tocopilla to break the southernmost 200 km of the seismic gap. In Tocopilla and several other communities in the backcountry, a majority of the structures were destroyed. Commencing in 2006, in close cooperation between the GFZ Potsdam (Germany), IPG Paris (France), the Universidad Catolica del Norte, Antofagasta and Universidad de Chile, Santiago (Chile), a network of 15 observatories equipped with seismic broadband and strong motion sensors, GPS receivers and magnetotelluric probes is being established to monitor the seismic gap. At the time of the Tocopilla earthquake, 12 sites were already deployed with the seismological instruments. Based on these data we relocate the mainshock and early aftershocks. The surface deformation field derived from InSAR data in Wide Swath and Image modes from ascending and descending tracks will be inverted for a distributed slip model using a grid of rectangular dislocations in an elastic half-space. We use broadband stations at teleseismic distances to image the spatio-temporal characteristics of seismic energy release during the earthquake. This analysis indicates a rupture length of approximately 200 km with almost unilateral southward propagation and a duration of approximately 200s. Rupture terminated on Mejillones Peninsula, exactly where an earlier large earthquake, the Mw 8 1995 Antofagasta event, had its northern limit. This is also where most of the early aftershocks focus. The structure beneath the Mejillones Peninsula seems to form a persistent barrier in the northern Chilean earthquake cycle. Based on our analysis, the fault plane of the Tocopilla earthquake fills roughly the southernmost third of the Iquique seismic gap

  6. High-Resolution Seismicity Image of the Shallow Part of the Subduction Zone Beneath Mejillones in Northern Chile

    Science.gov (United States)

    Kummerow, Jörn; Bloch, Wasja; Salazar, Pablo; Wigger, Peter; Asch, Günter; Shapiro, Serge A.

    2015-04-01

    We analyze slab-related seismicity which has been recorded by a recently (June 2013) installed local seismic monitoring system on the Mejillones peninsula in the forearc region of Northern Chile. The monitoring system consists of 20 seismic stations and is complemented by components of the permanent IPOC (Integrated Plate Boundary Obervatory Chile) seismic network, providing a singular on-shore possibility to study in detail the relatively shallow seismicity of the subducting Nazca slab. To date, about thousand local seismic events have been identified. Precise earthquake relocation involving a local 2.5D velocity model and improved arrival time picks from an iterative cross-correlation based technique allows to trace sharply the slab interface between 25km and 40km depth. Furthermore, we observe distinct and continuous seismic activity on a near-vertical structure which transects the subducting oceanic crust from 40km to 50km depth. Location, orientation and size of this plane correspond to the rupture fault of the MW6.8 Michilla intraslab earthquake which occurred weeks after the MW7.7 Tocopilla earthquake of November 2007. We discuss here particularly the results from cluster analysis and the spatio-temporal signatures of the recorded seismicity.

  7. Spatial characterization of land surface energy fluxes and uncertainty estimation at the Salar de Atacama, Northern Chile

    Science.gov (United States)

    Kampf, Stephanie K.; Tyler, Scott W.

    2006-02-01

    We use Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) data to estimate spatial energy flux and evaporation distributions at the Salar de Atacama, a playa in Northern Chile. Our approach incorporates ASTER surface kinetic temperature, emissivity, and reflectance data, ground-based meteorological measurements, and empirical parameters. Energy flux distributions are estimated using either spatially constant or spatially distributed values of model parameters, with spatially distributed parameters assigned separately to each land cover category in an image classification. We test the sensitivity of energy budget calculations to state variable and parameter values by conducting Monte Carlo simulations for regions with ground energy budget measurements. Results show that assigning spatially distributed model parameters via land cover classifications yields significant improvements to ground and sensible heat flux predictions. Latent heat fluxes cannot, however, be predicted with sufficient accuracy to allow estimation of area-integrated evaporative moisture loss at this low-evaporation playa.

  8. Osseous skeletal material and fish scales in marine sediments under the oxygen minimum zone off northern and central Chile

    Science.gov (United States)

    Milessi, Andrés C.; Sellanes, Javier; Gallardo, Víctor A.; Lange, Carina B.

    2005-08-01

    The significance of whale falls for the study of the biogeography, evolution and biodiversity of deep-sea biota has been recently recognized by international programs since large carcasses are known to give rise to biogenic chemosynthetic ecosystems. However, the plain accumulation of smaller bone material in the shallower settings of the continental shelf and upper slope under the hypoxic conditions of the Oxygen Minimum Zone (OMZ), has received much less attention. Here we describe new findings of skeletal material and fish scales in marine sediments under the OMZ off northern and central Chile which, combined with previous reports for the study area, lead us to suggest the existence of a band in the benthos of accumulation of bones and scales extending at least twenty degrees in latitude (18-38° S). Future studies should focus on the characterization of biotic communities living upon these resources in order to elucidate their peculiarities and importance in the Eastern South Pacific.

  9. Analysis of benthic macroinvertebrates and biotic indices to evaluate water quality in rivers impacted by mining activities in northern Chile

    Directory of Open Access Journals (Sweden)

    Alvial I.E.

    2013-02-01

    Full Text Available Catchments in the semiarid regions are especially susceptible to environmental perturbation associated with water scarcity, hydrological variations and overuse by anthropogenic activities. Using multivariate analysis to relate environmental and biological data, and diversity and biotic indices (ChBMWP, ChIBF, we analyzed the macroinvertebrate composition of 12 rivers of the semiarid region of northern Chile. A non-metric multidimensional scaling for macroinvertebrate taxa and a principal component analysis for environmental variables strongly separated upstream sites (e.g. Vacas Heladas and Malo Rivers, which presented low pH and high dissolved metal concentrations, from other sites. Effectively, CCA showed that metals and low pH, associated with the altitudinal gradient, determined the distributional patterns of macroinvertebrates in the Elqui catchment. The causes of these particular conditions could be related to geological processes and human impact. The biotic indices applied to the sampling sites corroborated and reflected these characteristics, with La Laguna and Turbio Rivers showing a diverse macroinvertebrate community and moderate to good water quality, and the Claro River showing favorable conditions for the development of aquatic biota, indicating its better quality relative to other stations. To the middle and low part of the basin, a change in the composition of the community was observed, with species that suggest an impact by an increase in organic matter, due to agricultural activities and urban settlements concentrated in this area. Our results suggest that macroinvertebrate taxa in northern Chile may be exceptional species, adapted to unfavorable geochemical conditions, and emphasize the need for protection of the semiarid basins of the region.

  10. Enfermedad de Chagas en poblaciones prehistóricas del norte de Chile Chagas disease in prehistoric populations of northern Chile

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    NANCY ORELLANA-HALKYER

    2010-12-01

    Full Text Available La enfermedad de Chagas es producida por el parásito Trypanosoma cruzi, el cual afecta tanto a seres humanos como a animales, en particular mamíferos marsupiales y placentarios. Las vías de transmisión son diversas, siendo una de las más importantes la vía vectorial, en la que participan insectos infectados con este parásito, animales y humanos. En este artículo de revisión discutimos los postulados sobre la vía de transmisión oral, los hallazgos de T. cruzi en momias de América y especialmente en las del norte de Chile. Presentamos además información que apunta a que la enfermedad de Chagas estuvo presente mucho antes de la conquista europea y de la construcción de viviendas de adobe. Comentamos las hipótesis sobre el vector domiciliado más importante de Sudamérica, Triatoma infestans, su antigüedad en la costa de Arica y los reportes más recientes de otros vectores silvestres. También se discute la información relacionada a la participación en el ciclo de T. cruzi de distintos mamíferos silvestres de Chile y asimismo proponemos el estudio paleoparasitológico en restos zooarqueológicos para conocer las especies de mamíferos reservónos de T. cruzi en la antigüedad.Chagas diseases is produced by a parasite named Trypanosoma cruzi, that affects humans and other marsupial and placental mammals. Transmission routes are diverse, but the most important transmission is the vector route, which involves the triatomine insects, wild and domestic infected animáis, and humans. Here we review the data about oral transmission route and the evidences of the etiological agent (Trypanosoma cruzi of Chagas disease in pre-Columbian American mummies, making a critical review of the infection in northern Chile. Moreover, we comment on the hypotheses suggested in relation to the most important vector of the infection in South América Triatoma infestans, its antiquity in the Arica coast, and the recent reports about other wild infected

  11. Geographic variation and phylogenetic relationships of Myiopagis olallai (Aves: Passeriformes; Tyrannidae), with the description of two new taxa from the Northern Andes.

    Science.gov (United States)

    Cuervo, Andrés M; Stiles, F Gary; Lentino, Miguel; Brumfield, Robb T; Derryberry, Elizabeth P

    2014-01-01

    Geographic variation in vocalizations, morphology and plumage patterns in New World flycatchers is little understood, particularly in rare species with disjunct distributions. We discovered a distinct new flycatcher of the genus Myiopagis from cloud forests of the northern Central Andes in Antioquia, Colombia. Comparisons of vocalizations and external morphology, and molecular phylogenetic analyses, demonstrate that the "Antioquia Myiopagis" is a unique lineage of the M. caniceps-olallai group. We show that three specimens collected in 1940-1951 from cloud forests of Serranía de Perijá in Venezuela, and traditionally assigned to M. caniceps, represent another distinct taxon that is closer to the "Antioquia Myiopagis" and M. olallai. Both new taxa, from Antioquia and Perijá, are described as subspecies of M. olallai. We present a phylogenetic hypothesis for the M. caniceps-olallai group, in which M. olallai and the "Antioquia Myiopagis" are phylogenetically nested within the polytypic M. caniceps, which consists of at least four distinct lineages, indicating that species diversity in this group could be underestimated.  PMID:25544202

  12. The 2007 M7.7 Tocopilla northern Chile earthquake sequence - along and across strike rupture segmentation

    Science.gov (United States)

    Schurr, B.; Asch, G.; Motagh, M.; Oncken, O.; Chong Diaz, G.; Barrientos, S. E.; Vilotte, J.

    2010-12-01

    In November 2007 a M7.7 earthquake occurred near the coastal town of Tocopilla in the southern part of a presumed seismic gap extending some 500 km along the northern Chile subduction zone. This major segment last broke in a magnitude ≧8.5 earthquake in 1877. Assuming a complete lock of the interface, it has accumulated more than 8 m of slip deficit. The contiguous segments to the north and south broke in M≧8 earthquakes in 2001 and 1995. Teams from Chile (Universidad Católica del Norte and Universidad de Chile), France (IPGP) and Germany (GFZ) started in 2006 to install semi-permanent multi-parameter observatories within the Integrated Plate Boundary Observatory Chile (IPOC) Initiative to monitor deformation at a variety of spatial and temporal scales in the final stage of the seismic cycle. At the time of the Tocopilla earthquake, 12 sites were equipped with seismic broadband and strong-motion sensors recording both the mainshock and its aftershock series. The earthquake rupture extended for about 160 km from the centre of the Mejillones peninsula (MP) to about 20 km north of the town of Tocopilla. Slip was confined to the depth range 30-55 km and concentrated in two patches in the north and south with a maximum of about 2.6 m. Hence the earthquake released only a fraction of the slip deficit and broke only the down-dip part of the plate interface, with the up-dip limit of the rupture approximately following the coastline. This poses the important question why rupture did not extend offshore, where the interface is presumably locked based on models of long-term interseismic deformation. We relocated more than 1000 aftershocks occurring in the week following the mainshock using hand-picked arrival times, cross-correlation based differential travel times and the double-difference algorithm. Despite the sparseness of the network, the aftershocks sharply define the plate interface. Seismicity in the first 24h is congruent to the slip distribution with the area

  13. Cronología y paleogeografía del Terciario de la Cuenca Intermontana de Iglesia septentrional, Andes de San Juan, Argentina Geochronology and paleogeographic of the Tertiary intermontaneous basin of northern Iglesia, Andes of San Juan, Argentina

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    G.H. Ré

    2003-03-01

    Full Text Available El sector norte de la cuenca no-marina de Iglesia, una cuenca a cuestas (piggyback del sistema plegado y corrido de Precordillera y al este de la Cordillera de los Andes, está subdividida en cinco subcuencas por altos estructurales con tendencia de orientación norte. La combinación de datos estratigráficos, de sísmica de reflexión y de geología de superficie con datos de estratigrafía magnética y dataciones de circones por trazas de fisión de depósitos volcánicos intercalados, permitieron determinar edades, correlaciones, y evolución paleogeográfica entre las subcuencas. Dos unidades estratigráficas distintas llenan la cuenca. La Secuencia 1, ligeramente proximal y con fuerte influencia volcánica se acumuló aproximadamente a los 17 Ma, cuando la cuenca de Iglesia era estrecha y elongada, pero sin disrupciones internas. Las secuencias 2 hasta la 11 se acumularon entre los 9 y los 4 Ma en un depocentro que primero se extendió a través del tiempo en forma simultánea con la subdivisión en subcuencas estructurales, y luego se restringió a la subcuenca estructural occidental. Resulta claro que las secuencias 2 a 11 corresponden al Grupo Iglesia, mientras que la asignación estratigráfica de la Secuencia 1 es incierta.The northern Iglesia nonmarine basin, piggyback to the Precordillera thrust belt and east of the main Andean ranges, is subdivided into 5 sub-basins by north-trending structural highs. We combine stratigraphic data from seismic reflection and surface geology with magnetic polarity stratigraphy and fission-track zircon dates on intercalated volcanic deposits to determine ages, correlations and paleogeographic evolution among the sub-basins. Two distinct stratigraphic units fill the basin. Sequence 1, with strong and seemingly proximal volcanic influence accumulated approximately 17 Ma when the Iglesia basin was narrow and elongate, but not internally disrupted. Sequences 2 through 11 accumulated between 9 and 4 Ma in

  14. INDIGENOUS MOBILIZATIONS AND ENVIRONMENTAL PROTESTS IN THE SALAR DE ATACAMA (NORTHERN CHILE)

    OpenAIRE

    Paola Bolados García; Guillaume Boccara

    2015-01-01

    Después del retorno a la democracia en Chile -a fines del siglo pasado-, se inicia un proceso de reconocimiento formal de los pueblos originarios a través de una política indígena y multicultural. No obstante, esta coincidió con el avance y la consolidación del modelo neoliberal impuesto durante el régimen militar a mediados de la década de 1970, el cual continuó privatizando recursos naturales concentrados en territorios indígenas. En este trabajo mostramos como este neoliberalismo multicult...

  15. INDIGENOUS MOBILIZATIONS AND ENVIRONMENTAL PROTESTS IN THE SALAR DE ATACAMA (NORTHERN CHILE

    Directory of Open Access Journals (Sweden)

    Paola Bolados García

    2015-06-01

    Full Text Available Después del retorno a la democracia en Chile -a fines del siglo pasado-, se inicia un proceso de reconocimiento formal de los pueblos originarios a través de una política indígena y multicultural. No obstante, esta coincidió con el avance y la consolidación del modelo neoliberal impuesto durante el régimen militar a mediados de la década de 1970, el cual continuó privatizando recursos naturales concentrados en territorios indígenas. En este trabajo mostramos como este neoliberalismo multicultural desplegado en un contexto de nuevas privatizaciones, fue contestado y resistido por las poblaciones indígenas atacameñas en el norte de Chile a mediados de la primera década del nuevo siglo, poniendo en crisis las relaciones con el estado y las empresas -principalmente mineras y turísticas-, presentes en su territorio. Nos centramos en las luchas emprendidas por las comunidades atacameñas a mediados del 2000 y sus intentos por recuperar los recursos naturales y culturales mercantilizados bajo un discurso de derechos indígenas y ambientales propagado por los gobiernos socialistas de Ricardo Lagos (2000-2006 y Michelle Bachelet (2006-2010.

  16. The text of the Agreement of 22 September 1982 between Chile and the Agency for the application of safeguards in connection with the supply of nuclear material from the United Kingdom of Great Britain and Northern Ireland

    International Nuclear Information System (INIS)

    The full text of the agreement of 22 September 1982 between Chile and the Agency for the application of safeguards to nuclear material supplied from the United Kingdom of Great Britain and Northern Ireland is presented

  17. Una nueva especie de Ithome Chambers (Lepidoptera: Cosmopterigidae: Chrysopeleiinae del norte de Chile A new species of Ithome Chambers (Lepidoptera: Cosmopterigidae: Chrysopeleiinae from northern Chile

    Directory of Open Access Journals (Sweden)

    HECTOR A VARGAS

    2004-06-01

    Full Text Available Se presenta la descripción del adulto, larva y pupa de Ithome tiaynai Vargas sp. n. Las larvas antófagas viven asociadas a Acacia macracantha Willd. (Fabaceae. La distribución de esta especie comprende los valles costeros de Azapa y Chaca, Primera Región de Chile. Ithome tiaynai es la primera especie descrita desde Chile para este géneroDescriptions of the adult, larva and pupa of Ithome tiaynai Vargas sp. n. are presented. The anthophagous larvae are associated with Acacia macracantha Willd (Fabaceae. The distribution of this species includes the coastal valleys of Azapa and Chaca, First Region of Chile. Ithome tiaynai is the first species described from Chile for this genus.

  18. "Un devorador de su propia especie". Violencia, justicia y cultura popular en Santa Rosa de los Andes: las formas de la autoridad a los ojos de un peón de oficio matador, Chile 1805

    Directory of Open Access Journals (Sweden)

    Daniel Moreno Bazaes

    2016-01-01

    Full Text Available A través del análisis microhistórico del proceso judicial seguido por las autoridades de la villa de Santa Rosa de Los Andes e intervenido por la Real Audiencia de Santiago contra Juan Francisco Varas, “peón-gañan” de la hacienda de Llay-Llay, responsable de a lo menos seis homicidios y otros tantos crímenes que atentaron contra el orden local y el gobierno civil, se pretende dar cuenta de los pormenores de la organización social en el Valle del Aconcagua a fines del siglo XVIII y durante los primeros años del siglo XIX. De modo que a través de la observación de las tensiones generadas por el uso indiscriminado de la violencia, el desacato y la desobediencia a la autoridad local, se desea mostrar uno de los rostros más violentos que presentaron los procesos de campesinización en Chile durante el periodo colonial, indagando en las formas en que los contemporáneos, la administración y autoridades locales reaccionaron frente a este tipo de prácticas consideradas como intolerables y excesivas. Por supuesto, se pretende dar cuenta delos mecanismos desplegados por controlar ese tipo de conductas y desde ahí profundizar en los horizontes que adoptaron lo justo y la autoridad frente a una cultura popular que se configuró al margen de la “civilidad”.

  19. Comprehensive observation and modeling of earthquake and temperature-related seismic velocity changes in northern Chile with passive image interferometry

    Science.gov (United States)

    Richter, Tom; Sens-Schönfelder, Christoph; Kind, Rainer; Asch, Günter

    2014-06-01

    We report on earthquake and temperature-related velocity changes in high-frequency autocorrelations of ambient noise data from seismic stations of the Integrated Plate Boundary Observatory Chile project in northern Chile. Daily autocorrelation functions are analyzed over a period of 5 years with passive image interferometry. A short-term velocity drop recovering after several days to weeks is observed for the Mw 7.7 Tocopilla earthquake at most stations. At the two stations PB05 and PATCX, we observe a long-term velocity decrease recovering over the course of around 2 years. While station PB05 is located in the rupture area of the Tocopilla earthquake, this is not the case for station PATCX. Station PATCX is situated in an area influenced by salt sediment in the vicinity of Salar Grande and presents a superior sensitivity to ground acceleration and periodic surface-induced changes. Due to this high sensitivity, we observe a velocity response of several regional earthquakes at PATCX, and we can show for the first time a linear relationship between the amplitude of velocity drops and peak ground acceleration for data from a single station. This relationship does not hold true when comparing different stations due to the different sensitivity of the station environments. Furthermore, we observe periodic annual velocity changes at PATCX. Analyzing data at a temporal resolution below 1 day, we are able to identify changes with a period of 24 h, too. The characteristics of the seismic velocity with annual and daily periods indicate an atmospheric origin of the velocity changes that we confirm with a model based on thermally induced stress. This comprehensive model explains the lag time dependence of the temperature-related seismic velocity changes involving the distribution of temperature fluctuations, the relationship between temperature, stress and velocity change, plus autocorrelation sensitivity kernels.

  20. Paleowetlands and regional climate change in the central Atacama Desert, northern Chile

    Science.gov (United States)

    Quade, Jay; Rech, Jason A.; Betancourt, Julio L.; Latorre, Claudio; Quade, Barbra; Rylander, Kate Aasen; Fisher, Timothy

    2008-05-01

    Widespread, organic-rich diatomaceous deposits are evidence for formerly wetter times along the margins of the central Atacama Desert, one of the driest places on Earth today. We mapped and dated these paleowetland deposits at three presently waterless locations near Salar de Punta Negra (24.5°S) on the western slope of the Andes. Elevated groundwater levels supported phreatic discharge into wetlands during two periods: 15,900 to ~ 13,800 and 12,700 to ~ 9700 cal yr BP. Dense concentrations of lithic artifacts testify to the presence of paleoindians around the wetlands late in the second wet phase (11,000?-9700 cal yr BP). Water tables dropped below the surface before 15,900 and since 8100 cal yr BP, and briefly between ~ 13,800 and 12,700 cal yr BP. This temporal pattern is repeated, with some slight differences, in rodent middens from the study area, in both paleowetland and rodent midden deposits north and south of the study area, and in lake level fluctuations on the adjacent Bolivian Altiplano. The regional synchroneity of these changes points to a strengthening of the South American Monsoon — which we term the "Central Andean Pluvial Event" — in two distinct intervals (15,900-13,800 and 12,700-9700 cal yr BP), probably induced by steepened SST gradients across the tropical Pacific (i.e., La Niña-like conditions).

  1. Paleowetlands and regional climate change in the central Atacama Desert, northern Chile

    Science.gov (United States)

    Quade, Jay; Rech, Jason A.; Betancourt, Julio L.; Latorre, Claudio; Quade, Barbra; Rylander, Kate Aasen; Fisher, Timothy

    2008-01-01

    Widespread, organic-rich diatomaceous deposits are evidence for formerly wetter times along the margins of the central Atacama Desert, one of the driest places on Earth today. We mapped and dated these paleowetland deposits at three presently waterless locations near Salar de Punta Negra (24.5°S) on the western slope of the Andes. Elevated groundwater levels supported phreatic discharge into wetlands during two periods: 15,900 to ~ 13,800 and 12,700 to ~ 9700 cal yr BP. Dense concentrations of lithic artifacts testify to the presence of paleoindians around the wetlands late in the second wet phase (11,000?–9700 cal yr BP). Water tables dropped below the surface before 15,900 and since 8100 cal yr BP, and briefly between ~ 13,800 and 12,700 cal yr BP. This temporal pattern is repeated, with some slight differences, in rodent middens from the study area, in both paleowetland and rodent midden deposits north and south of the study area, and in lake level fluctuations on the adjacent Bolivian Altiplano. The regional synchroneity of these changes points to a strengthening of the South American Monsoon — which we term the "Central Andean Pluvial Event" — in two distinct intervals (15,900–13,800 and 12,700–9700 cal yr BP), probably induced by steepened SST gradients across the tropical Pacific (i.e., La Niña-like conditions).

  2. Soil charcoal analysis as a climato-stratigraphical tool: The key case of Cordillera Real, northern Andes

    Energy Technology Data Exchange (ETDEWEB)

    Di Pasquale, G. [Dipartimento di Arboricoltura Botanica e Patologia Vegetale, Universita di Napoli Federico II, Via Universita 100, 80055 Portici (Italy); Impagliazzo, S., E-mail: stefania.impagliazzo@unina.i [Dipartimento di Arboricoltura Botanica e Patologia Vegetale, Universita di Napoli Federico II, Via Universita 100, 80055 Portici (Italy); Lubritto, C. [CIRCE, Dipartimento di Scienze Ambientali, II Universita di Napoli, and INNOVA, via Vivaldi, 43, 81100 Caserta (Italy); Marziano, M. [Dipartimento di Arboricoltura Botanica e Patologia Vegetale, Universita di Napoli Federico II, Via Universita 100, 80055 Portici (Italy); Passariello, I. [CIRCE, Dipartimento di Scienze Ambientali, II Universita di Napoli, and INNOVA, via Vivaldi, 43, 81100 Caserta (Italy); Ermolli, E. Russo [Dipartimento di Arboricoltura Botanica e Patologia Vegetale, Universita di Napoli Federico II, Via Universita 100, 80055 Portici (Italy)

    2010-04-15

    The present study represents the first attempt of reconstructing fire history through soil charcoal dating. The investigated area is located in the Guandera Biological Reserve (western Cordillera Real, northern Ecuador). Six AMS radiocarbon dating, performed at the base of five soil profiles allowed a fire phase to be identified during the Pleistocene-Holocene transition. A strong correspondence was highlighted between the age of the Guandera fires and the El Abra stadial, which is considered the Younger Dryas equivalent in South America. This local evidence of fires contributes to define the geographic area in which the El Abra stadial was recorded and suggests a wider use of the soil charcoal analysis.

  3. Soil charcoal analysis as a climato-stratigraphical tool: The key case of Cordillera Real, northern Andes

    International Nuclear Information System (INIS)

    The present study represents the first attempt of reconstructing fire history through soil charcoal dating. The investigated area is located in the Guandera Biological Reserve (western Cordillera Real, northern Ecuador). Six AMS radiocarbon dating, performed at the base of five soil profiles allowed a fire phase to be identified during the Pleistocene-Holocene transition. A strong correspondence was highlighted between the age of the Guandera fires and the El Abra stadial, which is considered the Younger Dryas equivalent in South America. This local evidence of fires contributes to define the geographic area in which the El Abra stadial was recorded and suggests a wider use of the soil charcoal analysis.

  4. First remarks on the nesting biology of Hypodynerus andeus (Packard) (Hymenoptera, Vespidae, Eumeninae) in the Azapa valley, northern Chile Primeiras observações sobre a biologia da nidificação de Hypodynerus andeus (Packard) (Hymenoptera, Vespidae, Eumeninae) no vale de Azapa, norte do Chile

    OpenAIRE

    Felipe Méndez-Abarca; Enrique A. Mundaca; Héctor A. Vargas

    2012-01-01

    First remarks on the nesting biology of Hypodynerus andeus (Packard) (Hymenoptera, Vespidae, Eumeninae) in the Azapa valley, northern Chile. Some aspects about the nesting biology of the potter wasp Hypodynerus andeus (Packard, 1869) are reported for the first time. Observations were carried out at the Azapa valley, coastal desert of northern Chile. A total of sixty nests were collected and examined, each composed by 1-14 cells, most of them found attached to concrete lamp posts. The only pre...

  5. Karyotypic polymorphism and evolution within and between the Liolaemus monticola (Iguanidae "northern 2n = 38-40" chromosome race populations in central Chile Polimorfismo cromosómico y evolución intra e inter poblacional de la raza cromosómica "Norte 2n = 28-40" de Liolaemus monticola (Iguanidae en Chile Central

    Directory of Open Access Journals (Sweden)

    MADELEINE LAMBOROT

    2001-03-01

    Full Text Available Chromosomal genotypes were scored from 359 Liolaemus monticola lizards of the "northern, 2n = 38-40" chromosomal race from 21 locality samples between the Maipo (and one of its tributaries and the Aconcagua (and one of its tributaries ribers, plus a sample from the interracial hybridization zone, and some representative locality samples of the "southern 2n = 34" and the "multiple fission 2n = 42-44" chromosomal races for comparisons. The first seven variable chromosomal pairs were coded as Mendelian genotypes and statistically summarized by several clustering and population genetic algorithms. Spatial and temporal differentiation was assessed by chromosome frequencies, chromosomal diversity and heterozygosity. While no differentiation was found for diversity in the "northern 2n = 38-40" race, chromosomal frequencies and heterozygosity showed significant spatial differentiation that permit distinguishing between the coastal, Andean and transversal mountain range populations. The sample of Cuesta Chacabuco may represent a hybrid zone between the other two range samples. The origin of the chromosomal rearrangements, the population cytogenetics, and the recombination patterns resulting from chromosomal heterozygosity are compared in these chromosomal races, thus expanding the geographical area. These patterns are discussed with respect to the evolution of this complex in Chile and the importance of the riverine barriers in central ChileSe cuantificaron los "genotipos" cromosómicos para 359 lagartijas de 21 muestras poblacionales de la raza "Norte, 2n = 38-40" comprendida entre los ríos: río Maipo y uno de sus afluentes el río Yeso y río Aconcagua (y uno de sus afluentes el río Juncal. Con fines comparativos agregamos una muestra de la zona de hibridación interracial, algunas muestras representativas de la raza "Sur 2n = 34" y una de la raza "múltiples fisiones 2n = 42-44". Los siete primeros pares cromosómicos variables fueron codificados

  6. The 2007 M7.7 Tocopilla northern Chile earthquake sequence: Implications for along-strike and downdip rupture segmentation and megathrust frictional behavior

    OpenAIRE

    Bernd Schurr; Günter Asch; Matthias Rosenau; Rongjiang Wang; Onno Oncken; Barrientos, S.; Salazar, P.; Vilotte, J. P.

    2012-01-01

    In 2007 a M7.7 earthquake occurred near the town of Tocopilla within the northern Chile seismic gap. Mainshock slip, derived from coseismic surface deformation, was confined to the depth range between 30-55 km. We relocated ~1100 events during six months before and one week after the mainshock. Aftershock seismicity is first congruent to the mainshock slip and then it spreads offshore west and northwest of Mejillones Peninsula (MP). Waveform modeling for 38 aftershocks reveals source mechanis...

  7. The ANDES Deep Underground Laboratory

    CERN Document Server

    Bertou, X

    2013-01-01

    ANDES (Agua Negra Deep Experiment Site) is a unique opportunity to build a deep underground laboratory in the southern hemisphere. It will be built in the Agua Negra tunnel planned between Argentina and Chile, and operated by the CLES, a Latin American consortium. With 1750m of rock overburden, and no close- by nuclear power plant, it will provide an extremely radiation quiet environment for neutrino and dark matter experiments. In particular, its location in the southern hemisphere should play a major role in understanding dark matter modulation signals.

  8. Prospección de lepidópteros antófagos asociados a Acacia macracantha Willd. (Fabaceae en el norte de Chile Survey of anthophagous lepidopteran larvae associated with Acacia macracantha Willd. (Fabaceae in northern Chile

    Directory of Open Access Journals (Sweden)

    Héctor A. Vargas

    2009-06-01

    Full Text Available Se efectuó una prospección de larvas de lepidópteros antófagos asociados a Acacia macracantha Willd. (Fabaceae en dos valles costeros del norte de Chile: Azapa y Chaca. Fueron registradas ocho especies, distribuidas en ocho géneros y cinco familias. La composición de especies del ensamble fue la misma en las dos localidades. Sin embargo, la abundancia del ensamble y la abundancia por especie fueron diferentes entre los valles.A survey of anthophagous lepidopteran larvae associated with Acacia macracantha Willd. (Fabaceae was made in two coastal valleys from northern Chile: Azapa and Chaca. Eight species, distributed in eight genera and five families, were recorded in the areas. Species composition was the same for both localities. However, assemblage abundance and species abundance were different between the valleys.

  9. Highlights of the new Emission Norm for the Regulation of Light Pollution in Northern Chile

    Science.gov (United States)

    Sanhueza, Pedro

    2015-08-01

    Due to the need to deal with the new menace of LEDS, which are very blue emitters, and to address other shortcomings regarding scattering and over illumination of the first lighting regulations passed in Chile in 1998 (DS 686/1998), the Chilean Ministry of Environment (MMA) approved new regulations by Presidential decree (DS 043/2012) on May 03, 2013. This new version of the regulations was developed by OPCC in collaboration with the MMA.This new environmental standard includes the following main restrictions:A full-cut-off requirement for general lighting, which means 0.49cd/Klumen at 90º (i.e., no light distribution above horizontal).For sport and recreational activities, an allowed level of 10cd/Klumen at 90º, together with a visor to cut upper-hemisphere emissions.Spectral restrictions divided into three regulated regions of the visible spectrum (as compared to the total light emission between 380 and 780nm): (a) not more than 15% of total light output in the range 300 to 380nm; (b) not more than 15% in the range 380 to 499nm; and (c) not more than 50% in the range 781nm to 1micron.Over illumination restricted to not more than 20% over the Chilean standard (NSEG 9 n71) for minimal levels in public lighting.Billboards with inner sources of illuminations (LED or plasma big screens) must emit no more than 50cd/m2 at night. No spectral restriction is applied.This new lighting regulation has not come into force yet, due to a delay in approving complementary technical protocols. Enforcement is also a critical issue to deal with, given that the institutional environmental framework in Chile is being modified.The OPCC is working with both the Ministry of Public Works and also Ministry of Housing, seeking to go beyond the new lighting regulation by applying a more restrictive approach in terms of spectral restriction, promoting the use of warm white LEDS with a CCT of 2.700 Kº and, in the case of outdoor illumination near professional observatories, monochromatic

  10. Kinematic and dynamic inversion of the 16 December earthquake in Northern Chile

    Science.gov (United States)

    Ruiz, S.; Lancieri, M.; Madariaga, R. I.; Sobiesiak, M.; Campos, J. A.

    2009-12-01

    We study the kinematic and dynamic rupture propagation of the M 6.7, intraplate, intermediate depth, slab push earthquake that occurred 16 December 2007, a month after the large interplate thrust event of Tocopilla, Chile (M 7.7). The occurrence of a slab push event after a large subduction earthquake is well explained by Coulomb stress transfer and crack dynamics. A dense seismic network, equipped with short period and accelerometers was deployed after the event of 14 November 2007 by the Task Force of GFZ Potsdam and the University of Chile in Santiago. This network was in place on December 16 providing the best seismic data set ever recorded for a Chilean earthquake. We have used it to do a detailed study of rupture processes. We localized the main event of December 16 and the aftershocks that occurred within 24 h of the main event. The main event was located at 43 km depth, while the aftershocks distribution covered a circular zone of 5 to 8 km of radius centered on the main shock epicenter and with depth ranging between [39 - 49] km. The aftershocks are distributed on an almost vertical plane that agrees with the almost vertical plane of the fault mechanism (86° dip) and all the aftershock have the same mechanism as the main event. We used eight of the nearest accelerometric records low pass filtered at 1 Hz, two of which were situated right above the hypocenter. We performed a non-linear kinematic inversion based on the neighborhood algorithm (NA) with an L2 norm. The velocity model was derived from previous work by GFZ. The earthquake is very well modeled by a circular rupture of radius between 5 and 8 km that propagated with a very low rupture velocity, that varies between 1 and 2 km/s. We need only a few non-linear parameters to model this event, parameter space has a dimension close to 6. The kinematic solution was validated using a full dynamic inversion method in which the rupture process is modeled using finite differences on a coarse grid with a slip

  11. Oxygenation variability in Mejillones Bay, off northern Chile, during the last two centuries

    Directory of Open Access Journals (Sweden)

    J. A. Díaz-Ochoa

    2011-01-01

    Full Text Available The Peru Chile Current ecosystem is characterized by high biological productivity and important fisheries. Although this system is likely to be severely affected by climate change, its response to current global warming is still uncertain. In this paper, we analyze 10–166 year-old sediments in two cores collected from Mejillones Bay, an anoxic sedimentary setting favorable for the preservation of proxies. Based on a 166-year chronology, we used proxies of bottom-water oxygenation (Mo, V, S, and the (lycopane + n−C35/n−C31 ratio and surface water productivity (biogenic opal, counts of diatom valves, biogenic Ba, organic carbon, and chlorins to reconstruct environmental variations in Mejillones Bay. During the last two centuries, a shift took place in the coastal marine ecosystem of Bahia Mejillones at decadal scales. This shift was characterized by intense ENSO-like activity, large-scale fluctuations in biological export productivity and bottom water oxygenation, and increased eolian activity (inferred from Ti/Al and Zr/Al. This short-term variability was accompanied by a gradual increase of sulfidic conditions that has intensified since the early 1960s.

  12. Enrichment of arsenic transforming and resistant heterotrophic bacteria from sediments of two salt lakes in Northern Chile.

    Science.gov (United States)

    Lara, José; Escudero González, Lorena; Ferrero, Marcela; Chong Díaz, Guillermo; Pedrós-Alió, Carlos; Demergasso, Cecilia

    2012-05-01

    Microbial populations are involved in the arsenic biogeochemical cycle in catalyzing arsenic transformations and playing indirect roles. To investigate which ecotypes among the diverse microbial communities could have a role in cycling arsenic in salt lakes in Northern Chile and to obtain clues to facilitate their isolation in pure culture, sediment samples from Salar de Ascotán and Salar de Atacama were cultured in diluted LB medium amended with NaCl and arsenic, at different incubation conditions. The samples and the cultures were analyzed by nucleic acid extraction, fingerprinting analysis, and sequencing. Microbial reduction of As was evidenced in all the enrichments carried out in anaerobiosis. The results revealed that the incubation factors were more important for determining the microbial community structure than arsenic species and concentrations. The predominant microorganisms in enrichments from both sediments belonged to the Firmicutes and Proteobacteria phyla, but most of the bacterial ecotypes were confined to only one system. The occurrence of an active arsenic biogeochemical cycle was suggested in the system with the highest arsenic content that included populations compatible with microorganisms able to transform arsenic for energy conservation, accumulate arsenic, produce H(2), H(2)S and acetic acid (potential sources of electrons for arsenic reduction) and tolerate high arsenic levels. PMID:22555750

  13. Draft genome sequence of chloride-tolerant Leptospirillum ferriphilum Sp-Cl from industrial bioleaching operations in northern Chile.

    Science.gov (United States)

    Issotta, Francisco; Galleguillos, Pedro A; Moya-Beltrán, Ana; Davis-Belmar, Carol S; Rautenbach, George; Covarrubias, Paulo C; Acosta, Mauricio; Ossandon, Francisco J; Contador, Yasna; Holmes, David S; Marín-Eliantonio, Sabrina; Quatrini, Raquel; Demergasso, Cecilia

    2016-01-01

    Leptospirillum ferriphilum Sp-Cl is a Gram negative, thermotolerant, curved, rod-shaped bacterium, isolated from an industrial bioleaching operation in northern Chile, where chalcocite is the major copper mineral and copper hydroxychloride atacamite is present in variable proportions in the ore. This strain has unique features as compared to the other members of the species, namely resistance to elevated concentrations of chloride, sulfate and metals. Basic microbiological features and genomic properties of this biotechnologically relevant strain are described in this work. The 2,475,669 bp draft genome is arranged into 74 scaffolds of 74 contigs. A total of 48 RNA genes and 2,834 protein coding genes were predicted from its annotation; 55 % of these were assigned a putative function. Release of the genome sequence of this strain will provide further understanding of the mechanisms used by acidophilic bacteria to endure high osmotic stress and high chloride levels and of the role of chloride-tolerant iron-oxidizers in industrial bioleaching operations. PMID:26925196

  14. Absolute paleointensity of the Earth's magnetic field during Jurassic: case study of La Negra Formation (northern Chile)

    Science.gov (United States)

    Morales, Juan; Goguitchaichvili, Avto; Alva-Valdivia, Luis M.; Urrutia-Fucugauchi, Jaime

    2003-08-01

    We carried out a detailed rock-magnetic and paleointensity study of the ˜187-Ma volcanic succession from northern Chile. A total of 32 consecutive lava flows (about 280 oriented standard paleomagnetic cores) were collected at the Tocopilla locality. Only 26 samples with apparently preserved primary magnetic mineralogy and without secondary magnetization components were pre-selected for Thellier paleointensity determination. Eleven samples coming from four lava flows yielded reliable paleointensity estimates. The flow-mean virtual dipole moments range from 3.7±0.9 to 7.1±0.5 (10 22 A m 2). This corresponds to a mean value of (5.0±1.8)×10 22 A m 2, which is in reasonably good agreement with other comparable quality paleointensity determinations from the Middle Jurassic. Given the large dispersion and the very poor distribution of reliable absolute intensity data, it is hard to draw any firm conclusions regarding the time evolution of the geomagnetic field. To cite this article: J. Morales et al., C. R. Geoscience 335 (2003).

  15. Response of forearc crustal faults to the megathrust earthquake cycle: InSAR evidence from Mejillones Peninsula, Northern Chile

    Science.gov (United States)

    Shirzaei, M.; Bürgmann, R.; Oncken, O.; Walter, T. R.; Victor, P.; Ewiak, O.

    2012-06-01

    We report on a rare example of aseismic response of a creeping fault to the earthquake cycle of a nearby megathrust. Interferometric synthetic aperture radar (InSAR) is used to detect and analyze shallow creep of two crustal faults at Mejilones Peninsula, Northern Chile, located in the hanging wall of the 2007 Mw 7.7 Tocopilla subduction earthquake. We generate two independent time series of surface deformation spanning ∼3.5 yr of late interseismic and ∼1.5 yr early postseismic deformation associated with this event. The analysis reveals creep on the Mejillones fault as well as on a previously unmapped fault to the west of the Mejillones fault. The InSAR deformation maps and distributed slip models obtained from the data reveal that fault creep reversed between the interseismic and postseismic periods. Given the regional stress field perturbations due to interseismic and coseismic deformation, we argue that the observed shallow creep and its slip reversal are directly linked to the megathrust seismic cycle. Moreover, from similar eastward dips but opposite slip directions of the two faults, we infer that fault strength must be very low and that the kinematics is controlled by crustal flexure associated with the seismic cycle on the underlying megathrust.

  16. Dynamic inversion of a Slab-push earthquake in Northern Chile

    Science.gov (United States)

    Ruiz, Sergio; Madariaga, Raul; Lancieri, Maria; Sobesiak, Monika

    2010-05-01

    We study the dynamic rupture propagation of a M 6.7 intraplate earthquake that occurred 16 December 2007, a month after a large thrust event of Tocopilla, Chile (M 7.7). The occurrence of a slab push event after a large subduction earthquake is well explained by Coulomb stress transfer models and crack dynamics. A dense seismic network, equipped with short period and accelerometers was deployed after the event of 14 November 2007 by the Task Force of GFZ Potsdam and the University of Chile in Santiago. This network was in place on December 16 providing an excellent data set for this earthquake. We used these data to make a detailed study of rupture processes. We localized the main event of December 16 and the aftershocks that occurred within 24 h of the main event. The main event was located at 43 km depth, while the aftershocks distribution covered a circular zone of 5 to 8 km of radius centred on the main shock epicentre. The aftershocks are distributed on an almost vertical plane that agrees with one of the fault planes of the mechanism (86° dip) and all the aftershock have the same mechanism as the main event. We used nearest accelerometric records in order to do dynamic inversion, two of these accelerometers were situated right above the hypocentre. We performed a non-linear dynamic inversion based on the neighbourhood algorithm (NA) and MonteCarlo methods with an L2 norm. The data was initially filtered in the 0.05-1 Hz. The velocity model was derived from previous work by GFZ. The earthquake was modelled using finite differences on a grid of variable size. Friction was modelled by the standard Ida slip weakening friction law. At each step of the inversion more than 32 full numerical simulations are carried in parallel. These simulations have been optimized in order to reduce the computer time to a minimum. The best models that result from dynamic inversion reduced the variance by more than 30 %, these models ruptured a relatively small zone of the fault

  17. Thermal biology of the fossorial rodent Ctenomys fulvus from the Atacama desert, northern Chile.

    Science.gov (United States)

    Cortés; Miranda; Rosenmann; Rau

    2000-12-01

    The Andean tuco-tuco, Ctenomys fulvus (Rodentia: Ctenomyidae) inhabits one of the most arid regions of the world, the Salar de Atacama, Northeast of Antofagasta, Chile (23 degrees 17'06"S, 68 degrees 05'43"W; 2.240 m.a.s.l). We found that a stable microclimate in burrows, a low evaporative water loss (EWL), and a diet of roots (59% water content) are the main factors that permit the survival of this fossorial species in harsh desert conditions. Large circadian variation in T(a) was observed above ground. Daily DeltaT(a) (T(a) max - T(a) min) = 37.9+/-0.2 degrees C in summer and in winter. In contrast, circadian variation of T(a) inside the burrows was only 5.8+/-0.5 degrees C in the same seasons. Relative humidity (RH) was 1.9-3.1% during the day, increasing to maximum values of 27% at night and early morning. Inside the burrows RH was higher and quite stable, ranging between 53.1 and 65%, independent of the time of day and season. EWL, measured between 10 and 25 degrees C, was low (1.26 mg/g h), and a moderate increase of 13-20% was observed at higher temperatures. The low EWL may prevent dehydration. However, because of the low heat loss capability, animals became hyperthermic (0.8-1.6 degrees C) in dry air at T(a)=30-35 degrees C. As T(a) during afternoon normally exceeded 35 degrees C, the microclimate of burrows provided the only way to avoid the lethal effects of hyperthermia. PMID:10880865

  18. Evaluation of metal mobility from copper mine tailings in northern Chile.

    Science.gov (United States)

    Lam, Elizabeth J; Gálvez, M E; Cánovas, M; Montofré, I L; Rivero, D; Faz, A

    2016-06-01

    This work shows the results obtained on a copper mine tailing in the Antofagasta Region, Chile. The tailing was classified as saline-sodic with high concentrations of metals, especially Cu and Fe, with pH 8.4. Our objectives were to (1) compare the physicochemical properties of the tailing with surrounding soils of the mine under study, and (2) evaluate the effect of two amendments (CaCO3 and compost) and their mixtures on Cu(2+), Mn, Fe, Zn, Mg(2+), and K(+) and Ca(2+), SO4 (2-), NO3 (-), and PO4 (3-) leaching. The data obtained were submitted to variance and covariance analysis. The results from the comparison between both substrates showed that in general, the tailing presented greater content of metals. Regarding tailing leaching, pH, electrical conductivity (EC), and concentration of the elements of interest were measured. The statistical analysis showed that Cu(2+) leaching and immobilization of Fe occurred to the greatest extent with compost. The EC decreased throughout the experiment with irrigation and increased upon treatment with compost. The major interactions found among the chemical parameters were (1) tailings without treatment, Cu(2+)/Fe and NO3 (-)/SO4 (2-); (2) tailings treated with CaCO3, Cu(2+)/K(+); (3) tailings treated with compost, NO3 (-)/SO4 (-2) and EC/Cu(2+); and (4) tailings treated with both amendments, EC/Fe and Cu(2+)/Fe. The ANOVA showed that the number of irrigations and the amendments statistically significantly affected the copper mobility and the organic amendment significantly influenced the iron mobility. PMID:26957432

  19. Potential of a Neutrino Detector in the ANDES Underground Laboratory for Geophysics and Astrophysics of Neutrinos

    CERN Document Server

    Machado, P A N; Nunokawa, H; Funchal, R Zukanovich

    2012-01-01

    The construction of the Agua Negra tunnels that will link Argentina and Chile under the Andes, the world longest mountain range, opens the possibility to build the first deep underground labo- ratory in the Southern Hemisphere. This laboratory has the acronym ANDES (Agua Negra Deep Experiment Site) and its overburden could be as large as \\sim 1.7 km of rock, or 4500 mwe, providing an excellent low background environment to study physics of rare events like the ones induced by neutrinos and/or dark matter. In this paper we investigate the physics potential of a few kiloton size liquid scintillator detector, which could be constructed in the ANDES laboratory as one of its possible scientific programs. In particular, we evaluate the impact of such a detector for the studies of geoneutrinos and galactic supernova neutrinos assuming a fiducial volume of 3 kilotons as a reference size. We emphasize the complementary roles of such a detector to the ones in the Northern Hemisphere neutrino facilities through some adv...

  20. Tapetes microbianos del Salar de Llamará, norte de Chile Microbial mats from the Llamará salt flat, northern Chile

    Directory of Open Access Journals (Sweden)

    CECILIA DEMERGASSO

    2003-09-01

    incluyendo cocos y bacilos no identificados. En todos los tapetes muestreados en el Salar se encontraron bacterias reductoras de sulfato.Stratified photosynthetic microbial mats are described from the Salar de Llamará, a salt flat basin located in the Atacama desert of northern Chile. Microscopic and spectrophotometric techniques were used. The thickness of the photic zone of these communities spans 8 to 30 mm. This is probably due to the grain size and mineralogical composition of associated sediments. Three different types of mats were recognized. A first one was characterized by a green pigmented layer; a second with orange and green coloured layers, and the third with orange and green layers and an additional purple layer. At one sampling site, no pigmented layers were present. Sediments underlying the mats were white, but in one site, black coloured sediments were observed; this dark colour is probably the result of iron sulphide precipitation. Predominant microorganisms in the orange pigmented layers were diatoms and unicellular cyanobacteria, mainly from the Cyanothece and Synechococcus groups. Filamentous cyanobacteria Microleus sp. and Oscillatoria sp. were the most abundant in the green layer. When interstitial brines reached salinities between 12 and 33 %, no diatoms were observed, and the coccoidal cyanobacteria from the Synechococcus, Cyanothece and Gloeocapsa groups and genus Gloeobacter predominated over filamentous Cyanobacteria in the green layer. The purple layer was built primarily of anoxygenic phototrophic bacteria similar to cells of the genera Chromatium and Thiocapsa. Absorption spectra revealed that chlorophyll a is the most abundant pigment in most of analyzed samples. Integrated values of chlorophyll a and bacteriochlorophyll a reached values of up to 230 and 144 mg m-2 along all of the pigmented zone, respectively. Abundant non-photosynthetic microorganisms were found in the mats, including unidentified cocci and bacilli. Sulphate reducing

  1. New chemical and original isotopic data on waters from El Tatio geothermal field, Northern Chile

    International Nuclear Information System (INIS)

    The El Tatio geothermal field is located at an height of 4200-4300 m on the Cordillera de los Andes (Altiplano). Geysers, hot pools and mudpots in the geothermal field and local meteoric waters were sampled in April 2002 and analyzed for major and trace elements, δ2H, δ18O and 3H of water, δ34S and δ18O of dissolved sulfate, δ13C of dissolved total carbonate, and 87Sr/86Sr ratio of aqueous strontium. There are two different types of thermal springs that field, that are chloride-rich water and sulfate-rich water. The chemical composition of chloride springs is controlled by magma degassing and by water-rock interaction processes. Sulfate springs are fed by shallow meteoric water heated by ascending gases. In keeping with the geodynamic setting and nature of the reservoir rocks, chloride water is rich in As, B, Cs, Li; on the other hand, sulfate waste is enriched only in B relative to local meteoric water. Alternatively to a merely meteoric model, chloride waters can be interpreted as admixtures of meteoric and magmatic (circa andesitic) water, which moderately exchanges oxygen isotopes with rocks at a chemical Na/K temperature of about 270degC in the main reservoir, and then undergoes loss of vapor (and eventually mixing with shallow water) and related isotopic effects ascent to the surface. These chloride waters do not present tritium and can be classified as submodern (pre-1952). A chloride content of 5,400 mg/l is estimated in the main reservoir, for which δ2H and δ18O values, respectively of -78 per mille and -6.9 per mille, are calculated applying the multistage-steam separation isotopic effects between liquid and vapor. From these data, the meteoric recharge (Cl≅0 mg/l) of the main reservoir should approach a composition of -107 per mille in δ2H and -14.6 per mille in δ18O, when a magmatic water of δ2H=-20 per mille, δ18O=+10 per mille and Cl=17,500 mg/l is assumed. The 87Sr/86 ratios of the hot springs are quite uniform (0.70876 to 0.70896), with

  2. Cronología y paleogeografía del Terciario de la Cuenca Intermontana de Iglesia septentrional, Andes de San Juan, Argentina Geochronology and paleogeographic of the Tertiary intermontaneous basin of northern Iglesia, Andes of San Juan, Argentina

    OpenAIRE

    G.H. Ré; T.E. Jordan; Kelley, S.

    2003-01-01

    El sector norte de la cuenca no-marina de Iglesia, una cuenca a cuestas (piggyback) del sistema plegado y corrido de Precordillera y al este de la Cordillera de los Andes, está subdividida en cinco subcuencas por altos estructurales con tendencia de orientación norte. La combinación de datos estratigráficos, de sísmica de reflexión y de geología de superficie con datos de estratigrafía magnética y dataciones de circones por trazas de fisión de depósitos volcánicos intercalados, permitieron de...

  3. Exhumation history of the Northern Andes from the Cenozoic syn-tectonic sedimentary fill of the Middle Magdalena Valley Basin, Colombia

    Science.gov (United States)

    Moreno, C. J.; Caballero, V. M.; Horton, B. K.; Mora, A.

    2009-12-01

    The Central Cordillera and the Eastern Cordillera of the northern Andes form the western and eastern flanks of the Colombian Middle Magdalena Valley Basin, respectively. Previous estimates of the timing of onset of exhumation of the two cordilleras vary, and although some recent studies have been in agreement, more work is needed to develop a clear picture. The spatial and chronological distribution of deformation has direct implications for the shortening history of the greater South American Andean margin, as well as for improving predictions of the rapid, lateral facies changes associated with the varying nearby sediment sources. Field-based analyses of the basin fill using paleocurrent measurements of trough-cross-beds, clast imbrication and flute casts, not only provide new insights into the tectonic history, but directly complement recent detrital zircon U-Pb work completed in the MMVB. Between the lower and upper Paleocene strata, the paleocurrent direction shifts from northward to eastward, indicating that uplift of the Central Cordillera was underway by the mid-Paleocene and consistent with the shift from a cratonic to Central Cordilleran sediment source observed in the detrital zircon record. This paleocurrent shift occurs coevally with a shift from delta to fluvial facies. An eastward paleoflow in upper Eocene through lowest Oligocene strata indicate a continuing influence of the Central Cordillera. Paleocurrent directions in the lower Oligocene deposits are highly variable, and, beginning in the middle Oligocene strata, show a switch to a dominantly westward orientation that continues through the Neogene. As the orientation changes, deposits show an increase in energy from muddy, meandering river deposits, to coarser, braided channel facies. We attribute this switch, from eastward to westward paleocurrent orientations, to the onset of exhumation of the Eastern Cordillera. The results of a current, detailed sandstone petrographic study combined with

  4. Depositación atmosférica de nitrógeno en un transecto valle longitudinal-cordillera de Los Andes, centro-sur de Chile Atmospheric deposition of nitrogen in a transect from the Central Valley to Cordillera de Los Andes, south-central Chile

    OpenAIRE

    Oyarzún, Carlos E; ROBERTO GODOY; SERGIO LEIVA

    2002-01-01

    El aumento de las actividades agrícolas y ganaderas en el centro-sur de Chile puede producir elevadas emisiones de nitrógeno hacia la atmósfera (mayormente NH3). El amoniaco es transportado por corrientes de aire y depositado en el suelo y vegetación. El presente estudio evalúa la depositación atmosférica de compuestos nitrogenados (NO3- y NH4+) en la química de las precipitaciones en un transecto altitudinal de 66 km, desde los alrededores de la ciudad de Osorno (40º 35' S, 72º 57' O, 55 m d...

  5. Multiple Sulfate Isotopic Evidence on the Formation of Oxide Copper Ore at Spence, Atacama Desert, Northern Chile

    Science.gov (United States)

    Sun, T.; Bao, H.; Reich, M.; Palacios, C.

    2007-12-01

    In the Atacama Desert of northern Chile, one of the world's richest metallogenic provinces, porphyry copper deposits are characterized by the unique occurrence of atacamite in their oxidized zones. The origin and formation of the oxide zone of these copper deposits is, however, controversial. It was proposed that Cl-rich deep formation water pumping-up events along faults by earthquakes, after onset of the hyperaridity, were required (Cameron et al., 2007). Their model would imply that supplies of saline deep formation water from fractures to the surface should have left behind a homogeneous or fracture-controlled salt profile from surface down to the oxide zone. While no excluding the deep formation water model in other deposit, here we propose that, in our sampling region, the alternative saline source, which is critical for atacamite formation, could be locally evaporated groundwater, Cl-rich salts leached from arid surface by meteoric water, or brines from eastern salar basins at a time when the climate in northern Chile was changing from arid to hyperarid. At this climate transition, arid- requiring minerals such as atacamite in the oxide zone were formed and, more importantly, preserved upon evaporation beneath the surface alluvial deposits. Since salt accumulation at the surface remain active during hyperarid condition, our model would predict that water-soluble salt profile from surface to the oxide zone should have a characteristic pattern: salts with an atmospheric component on the surface gradually transitioning to salts of the oxide ore zone on the bottom and a mixing zone in between. To test these two alternative models, we focus on sulfate salts, one of the common water-soluble salts in arid environments. An added advantage is that sulfate accumulated on desert surface has a secondary atmospheric component that bears a unique triple oxygen isotope signature, easily distinguishable from sulfate formed by the oxidation of sulfide minerals at the oxide

  6. Source apportionment of PM10 and PM2.5 in a desert region in northern Chile

    International Nuclear Information System (INIS)

    Estimating contributions of anthropogenic sources to ambient particulate matter (PM) in desert regions is a challenging issue because wind erosion contributions are ubiquitous, significant and difficult to quantify by using source-oriented, dispersion models. A receptor modeling analysis has been applied to ambient PM10 and PM2.5 measured in an industrial zone ∼ 20 km SE of Antofagasta (23.63°S, 70.39°W), a midsize coastal city in northern Chile; the monitoring site is within a desert region that extends from northern Chile to southern Perú. Integrated 24-hour ambient samples of PM10 and PM2.5 were taken with Harvard Impactors; samples were analyzed by X Ray Fluorescence, ionic chromatography (NO3− and SO4=), atomic absorption (Na+, K+) and thermal optical transmission for elemental and organic carbon determination. Receptor modeling was carried out using Positive Matrix Factorization (US EPA Version 3.0); sources were identified by looking at specific tracers, tracer ratios, local winds and wind trajectories computed from NOAA's HYSPLIT model. For the PM2.5 fraction, six contributions were found — cement plant, 33.7 ± 1.3%; soil dust, 22.4 ± 1.6%; sulfates, 17.8 ± 1.7%; mineral stockpiles and brine plant, 12.4 ± 1.2%; Antofagasta, 8.5 ± 1.3% and copper smelter, 5.3 ± 0.8%. For the PM10 fraction five sources were identified — cement plant, 38.2 ± 1.5%; soil dust, 31.2 ± 2.3%; mineral stockpiles and brine plant, 12.7 ± 1.7%; copper smelter, 11.5 ± 1.6% and marine aerosol, 6.5 ± 2.4%. Therefore local sources contribute to ambient PM concentrations more than distant sources (Antofagasta, marine aerosol) do. Soil dust is enriched with deposition of marine aerosol and calcium, sulfates and heavy metals from surrounding industrial activities. The mean contribution of suspended soil dust to PM10 is 50 μg/m3 and the peak daily value is 104 μg/m3. For the PM2.5 fraction, suspended soil dust contributes with an average of 9.3 μg/m3 and a peak daily

  7. Interactions between basement and cover during the evolution of the Salar de Atacama Basin, northern Chile

    Directory of Open Access Journals (Sweden)

    Nelson Muñoz

    2002-07-01

    Full Text Available ABSTRACT A reinterpretation of the structural style on the eastern Cordillera Domeyko and the adjacent Salar de Atacama Basin reveals the existence of west-dipping, high-angle, thrust-faults extending below the Cordillera Domeyko and Cordón de Lila, resulting from inversion of Cretaceous extensional faults, that transferred west-ward their displacement into the cover, generating fault-propagation and detachment folds. The most conspicuous of these structures is the Cordillera de la Sal. Contractional structures in the Cordillera Domeyko involved a Paleozoic crystalline, volcanic, and sedimentary, uplifted basement. Seismic reflection sections and available surface geology allows to study the interactions between development of the thick-skinned basement structures, sedimentation within the basin, and the thin-skinned deformation in the sedimentary cover. Geometry of the units in the basin continuously modified. Anticline growth above basement thrust-faults locally controlled syn-thrusting sequences, and generated progressive unconformities. Stratigraphic architecture in the basin seems to have been mainly controlled by tectonic activity. Tectonism generated accommodation space, altered base levels, and controlled source areas. The stratigraphy and geometry of the basin deposits resulted mainly from the succession of the following events: local extensional subsidence during the Early to Late Cretaceous, uplift of the Cordillera Domeyko during the latest Cretaceous to Miocene, uplift of the Puna, and subsidence probably caused by flexural response of the lithosphere during thrust-sheet loading, and sediment accumulationRESUMEN Interacciones entre el basamento y la cobertura durante la evolución de la Cuenca del Salar de Atacama, norte de Chile. La reinterpretación del estilo estructural del borde oriental de la Cordillera Domeyko y de la adyacente cuenca del Salar de Atacama, basada en el análisis de la geología de superficie y de perfiles s

  8. Characterization of land surface energy fluxes at the Salar de Atacama, Northern Chile using ASTER image classification

    Science.gov (United States)

    Kampf, S. K.; Tyler, S. W.

    2003-12-01

    Models of land surface energy fluxes often use remotely sensed data to derive surface temperature, albedo, and emissivity, important parameters in energy budget calculations. The ability to determine the spatial distribution of these parameters can lead to improved estimations of the spatial variability of land surface energy fluxes. However, other parameters used in energy flux calculations such as aerodynamic resistance are not directly linked to quantities commonly derived from remotely sensed data. If images can be accurately classified into separate land cover types, empirically determined values of unknown parameters can then be assigned separately to each land cover classification. This study examines several techniques of determining the spatial distribution of land surface energy fluxes at the Salar de Atacama, a large playa in northern Chile. Fluxes are calculated using Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) Level 2 surface kinetic temperature, surface emissivity, and surface reflectance data in conjunction with ground-based meteorological measurements. Energy fluxes are calculated initially by applying a single value of aerodynamic resistance to the entire image area. Subsequently, the ASTER scene is classified into distinct land cover types, and land surface roughness is characterized using the ratio of ASTER band 3N (nadir-viewing) to band 3B (back-viewing). Separate values of aerodynamic resistance are then assigned to each land cover type, and energy fluxes over the entire Salar de Atacama are calculated using these spatially distributed aerodynamic resistance values. Results of both energy flux calculation techniques are evaluated at several sites on the playa using ground-based energy flux measurements.

  9. Soils at the hyperarid margin: The isotopic composition of soil carbonate from the Atacama Desert, Northern Chile

    Science.gov (United States)

    Quade, Jay; Rech, Jason A.; Latorre, Claudio; Betancourt, Julio L.; Gleeson, Erin; Kalin, Mary T.K.

    2007-01-01

    We evaluate the impact of exceptionally sparse plant cover (0–20%) and rainfall (2–114 mm/yr) on the stable carbon and oxygen composition of soil carbonate along elevation transects in what is among the driest places on the planet, the Atacama Desert in northern Chile. δ13C and δ18O values of carbonates from the Atacama are the highest of any desert in the world. δ13C (VPDB) values from soil carbonate range from -8.2% at the wettest sites to +7.9% at the driest. We measured plant composition and modeled respiration rates required to form these carbonate isotopic values using a modified version of the soil diffusion model of [Cerling (1984) Earth Planet. Sci. Lett.71, 229–240], in which we assumed an exponential form of the soil CO2 production function, and relatively shallow (20–30 cm) average production depths. Overall, we find that respiration rates are the main predictor of the δ13C value of soil carbonate in the Atacama, whereas the fraction C3 to C4 biomass at individual sites has a subordinate influence. The high average δ13C value (+4.1%) of carbonate from the driest study sites indicates it formed&mdahs;perhaps abiotically—in the presence of pure atmospheric CO2. δ18O (VPDB) values from soil carbonate range from -5.9% at the wettest sites to +7.3% at the driest and show much less regular variation with elevation change than δ13C values. δ18O values for soil carbonate predicted from local temperature and δ18O values of rainfall values suggest that extreme (>80% in some cases) soil dewatering by evaporation occurs at most sites prior to carbonate formation. The effects of evaporation compromise the use of δ18O values from ancient soil carbonate to reconstruct paleoelevation in such arid settings.

  10. A new genus of Toads (Amphibia: Anura: Bufonidae) from the Pacific Slopes of the Andes in Northern Ecuador and Southern Colombia, with the description of two new species

    NARCIS (Netherlands)

    Hoogmoed, M.S.

    1985-01-01

    The genus Andinophryne, characterized by the presence of an omosternum, an externally visible tympanum, elongate parotoids and extensively webbed hands and feet is described from the Pacific versant of the Andes in northwestern Ecuador and southwestern Colombia. Two new species, Andinophryne colomai

  11. Seasonal Changes in Soil Moisture Content in Northern Chile and Southern California Inferred from SAR data

    Science.gov (United States)

    Scott, C. P.; Lohman, R. B.

    2015-12-01

    InSAR-based studies of the seismic cycle have focused primarily on the interferometric phase observations, which place constraints on the amount of uplift or subsidence of the ground surface. Recently, coseismic InSAR coherence has also been used to rapidly identify urban damage, surface ruptures, cracking, and soil liquefaction. Here we demonstrate that time-variable correlation and amplitude data contain additional information about surficial processes and material properties that may affect ground deformation and seismic hazard. In the use of correlation for hazard response, distinguishing the coseismic signal from other changes in surface properties associated with variations in soil moisture content, vegetation and snow cover, and wind is critical. Building SAR-based catalogues of ground properties will therefore improve the reliability of rapid response and aid in the designing of future SAR missions to better map surface ruptures, off-fault deformation, and coseismic damage. In this project, we characterize the seasonal variations in the soil moisture content in the Northern Chilean Coastal Cordillera and Southern California. The extreme climate of the Atacama Desert characterized by hyperaridity and coastal fog during the non-summer months creates an ideal landscape for exploring surface properties. We produce interferograms using L-band ALOS data (λ = 23.6 cm) that span 46 days to three years and have perpendicular baselines less than 1500 m. We observe a strong seasonal dependence on correlation that extends to the maximum elevation of the fog penetration. Interferograms with only austral summer acquisitions are more correlated than interferograms with one or both acquisitions in the autumn, winter or spring, even when the summer interferograms span multiple years. We propose that the seasonal dependence is due to small changes in the radar path length caused by variable soil moisture content in the very shallow subsurface. We further consider local

  12. The Early Andean Magmatic Province (EAMP): 40Ar/ 39Ar dating on Mesozoic volcanic and plutonic rocks from the Coastal Cordillera, northern Chile

    Science.gov (United States)

    Oliveros, Verónica; Féraud, Gilbert; Aguirre, Luis; Fornari, Michel; Morata, Diego

    2006-10-01

    The Early Andean Magmatic Province (EAMP), consists of about 150 000 km 3 of volcanic and plutonic units in the Coastal Cordillera of northern Chile and southern Peru and represents a major magmatic Mesozoic event in the world, for which the precise age of the thick volcanic series was unknown. Thirty 40Ar/ 39Ar analyses were carried out on primary mineral phases of volcanic and plutonic rocks from northern Chile (18°30'-24°S). Reliable plateau and "mini plateau" ages were obtained on plagioclase, amphibole and biotite from volcanic and plutonic rocks, despite widespread strong alteration degree. In the Arica, Tocopilla and Antofagasta (700 km apart) regions, the ages obtained on lava flows constrain the volcanic activity between 164 and 150 Ma and no N-S migration of volcanism is observed. The uppermost lava flows of the volcanic sequence at the type locality of the La Negra Formation extruded at ca. 153-150 Ma, suggesting the end of the volcanic activity of the arc at that time. The oldest volcanic activity occurred probably at ca. 175-170 Ma in the Iquique area, although no plateau age could be obtained. The plutonic bodies of the same regions were dated between ca. 160 and 142 Ma, indicating that they were partly contemporaneous with the volcanic activity. At least one volcanic pulse around 160 Ma is evidenced over the entire investigated reach of the EAMP, according to the ages found in Arica, Tocopilla, Michilla and Mantos Blancos regions. The episodic emplacement of huge amounts of subduction related volcanism is observed throughout the whole Andean history and particularly during the Jurassic (southern Peru, northern Chile and southern Argentina). These events probably correspond to periodic extensional geodynamic episodes, as a consequence of particular subduction conditions, such as change of obliquity of the convergence, change in the subduction angle, slab roll back effect or lower convergence rate, that remain to be precisely defined.

  13. International Uranium Resources Evaluation Project (IUREP) national favourability studies: Chile

    International Nuclear Information System (INIS)

    Chile has an area of 740,760 square kilometers. The capital is Santiago. The country is 4,183 km. long and ranges from 22.5 to about 354 km. in width. Its chief topographic features para]lei each other - the Coastal Range, Andes Mountains and Central Valley. The Coastal Range rises to 2,130 meters in the north, but averages from 610 to 700 meters high generally. The range plunges into the Pacific Ocean far south of Valparaiso and reappears in the southern archipelagic islands. The Andes extend along nearly the entire length of Chile and contain 100 volcanoes. Andean peaks range mostly from 3,000 to 6,700 meters in elevation. In southern Chile the Andes are lower, and contain about a dozen major lakes. The mountains disappear in Chilean Patagonia, but reappear at Cape Horn. The Central Valley lies between the Coastal Range and the Andes, being best defined in the midland region as a 64 to 72 km sloping plain. It is the Chilean heartland with three-quarters of the country's population. Salt basins are found over much of northern Chile in the very arid desert, while the region south of the Gulf of Reloncavi consists of unpopulated islands, fjords, channels and heavily forested mountains. The Strait of Magellan, the Tierra del Fuego archipelago and a flat grassland area make up the extreme southern end of the country. Much of Chile is subject to flash floods, earthquakes, volcanic eruptions, landslides and avalanches. In September 1976 the Comision Chilena de Energia Nuclear (CCEN) was given exclusive rights to negotiate contracts with private companies for the exploration, development and mining of uranium and other radioactive minerals. The new law provides the CCEN with considerable flexibility in the terms of the contracts. Pre-964 owners of uranium deposits may reach agreements with foreign companies to mine the uranium, but since 1964 all uranium has belonged to the state. Uranium produced in the country can only be exported after Chile's needs have been met. The

  14. Tapetes microbianos del Salar de Llamará, norte de Chile Microbial mats from the Llamará salt flat, northern Chile

    OpenAIRE

    CECILIA DEMERGASSO; GUILLERMO CHONG; PEDRO GALLEGUILLOS; LORENA ESCUDERO; MAIRA MARTíNEZ-ALONSO; ISABEL ESTEVE

    2003-01-01

    Se estudiaron las comunidades estratificadas de microorganismos fotosintéticos que se encuentran en el Salar de Llamará ubicado en el desierto de Atacama, norte de Chile, mediante métodos microscópicos y espectrofotométricos. El espesor de la zona fótica de los tapetes descritos varió entre 8 y 30 mm lo cual podría atribuirse a la granulometría y la composición mineralógica de los sedimentos. Se diferencian tres tipos de tapetes. El primero con una única capa pigmentada de color verde; el seg...

  15. Reestablecimiento de Choromytilus chorus (Molina, 1782) (Bivalvia: Mytilidae) en el norte de Chile Reestablishment of Choromytilus chorus (Molina, 1782) (Bivalvia: Mytilidae) in northern Chile

    OpenAIRE

    Miguel Avendaño; Marcela Cantillánez

    2011-01-01

    Hasta fines del siglo pasado no existían registros de la presencia de Choromytilus chorus al norte de los 23°S, pese a antecedentes que señalaban su existencia en épocas pasadas. Ciertos cambios relacionados con las masas de agua costeras de esta zona, habrían generado la ausencia o escasez que presentaba el entorno costero actual. Sin embargo, hace una década atrás, su presencia en el norte de Chile, comienza a tener connotación pesquera. En el presente trabajo se confirma su reestablecimien...

  16. ESTANDARIZACION DE LAS TASAS DE CAPTURA DE RECURSOS PELAGICOS DE LA ZONA NORTE DE CHILE STANDARDIZATION OF CATCH RATES OF THE PELAGIC FISH RESOURCES IN THE NORTHERN CHILE

    OpenAIRE

    Gabriela Böhm; Eleuterio Yáñez; Fernando Espíndola

    2005-01-01

    Se usó el modelo lineal generalizado (MLG) para estandarizar el índice de abundancia relativa, captura por unidad de esfuerzo (CPUE) de anchoveta (Engraulis ringens), sardina (Sardinops sagax) y jurel (Trachurus murphyi), en la zona norte de Chile (18º21-24ºS), entre 1987 y 1997. Para la anchoveta se toma en cuenta la categoría de embarcación, la zona de pesca, la fase lunar, la estación del año, el año y la temperatura superficial del mar (TSM). En tanto que para la sardina y el jurel se tom...

  17. 40Ar/39Ar ages from blueschists of the Jambaló region, Central Cordillera of Colombia : implications on the styles of accretion in the Northern Andes

    OpenAIRE

    Bustamante, A.; Juliani, C.; C. M. Hall; Essene, E. J.

    2011-01-01

    This paper presents the first argon dating of blueschists from the Jambaló area (Cauca Department) in the Central Cordillera of the Colombian Andes. Step-heating 40Ar/39Ar spectra were obtained for mica from several lenses of blueschists including greenschist facies rocks. The blueschists are mainly constituted of preserved lenticular cores in strongly mylonitic rocks, which resulted from retrometamorphic processes that affected the high pressure rocks during their exhumation. The majority of...

  18. Trends and ENSO/AAO Driven Variability in NDVI Derived Productivity and Phenology alongside the Andes Mountains

    Directory of Open Access Journals (Sweden)

    Francisco J. Meza

    2013-03-01

    Full Text Available Increasing water use and droughts, along with climate variability and land use change, have seriously altered vegetation growth patterns and ecosystem response in several regions alongside the Andes Mountains. Thirty years of the new generation biweekly normalized difference vegetation index (NDVI3g time series data show significant land cover specific trends and variability in annual productivity and land surface phenological response. Productivity is represented by the growing season mean NDVI values (July to June. Arid and semi-arid and sub humid vegetation types (Atacama desert, Chaco and Patagonia across Argentina, northern Chile, northwest Uruguay and southeast Bolivia show negative trends in productivity, while some temperate forest and agricultural areas in Chile and sub humid and humid areas in Brazil, Bolivia and Peru show positive trends in productivity. The start (SOS and length (LOS of the growing season results show large variability and regional hot spots where later SOS often coincides with reduced productivity. A longer growing season is generally found for some locations in the south of Chile (sub-antarctic forest and Argentina (Patagonia steppe, while central Argentina (Pampa-mixed grasslands and agriculture has a shorter LOS. Some of the areas have significant shifts in SOS and LOS of one to several months. The seasonal Multivariate ENSO Indicator (MEI and the Antarctic Oscillation (AAO index have a significant impact on vegetation productivity and phenology in southeastern and northeastern Argentina (Patagonia and Pampa, central and southern Chile (mixed shrubland, temperate and sub-antarctic forest, and Paraguay (Chaco.

  19. The 2007 M7.7 Tocopilla northern Chile earthquake sequence: Implications for along-strike and downdip rupture segmentation and megathrust frictional behavior

    Science.gov (United States)

    Schurr, B.; Asch, G.; Rosenau, M.; Wang, R.; Oncken, O.; Barrientos, S.; Salazar, P.; Vilotte, J.-P.

    2012-05-01

    In 2007 a M7.7 earthquake occurred near the town of Tocopilla within the northern Chile seismic gap. Main shock slip, derived from coseismic surface deformation, was confined to the depth range between 30 and 55 km. We relocated ˜1100 events during six months before and one week after the main shock. Aftershock seismicity is first congruent to the main shock slip and then it spreads offshore west and northwest of Mejillones Peninsula (MP). Waveform modeling for 38 aftershocks reveals source mechanisms that are in the majority similar to the main shock. However, a few events appear to occur in the upper plate, some with extensional mechanisms. Juxtaposing the Tocopilla aftershocks with those following the neighboring 1995 Antofagasta earthquake produces a striking symmetry across an EW axis in the center of MP. Events seem to skirt around MP, probably due to a shallower Moho there. We suggest that the seismogenic coupling zone in northern Chile changes its frictional behavior in the downdip direction from unstable to mostly conditionally stable. For both earthquake sequences, aftershocks agglomerate in the conditionally stable region, whereas maximum inter-seismic slip deficit and co-seismic slip occurs in the unstable region. The boundary between the unstable and conditionally stable zones parallels the coastline. We identify a similar segmentation for other earthquakes in Chile and Peru, where the offshore segments break in great M > 8 earthquakes, and the onshore segments in smaller M < 8 earthquakes. Using critical taper analysis, we demonstrate a causal relationship between varying slip behavior on the interface and forearc wedge anatomy that can be attributed to spatial variations in the rate-dependency of friction.

  20. Shape of the plate interface near the Mejillones Peninsula in Northern Chile inferred from high resolution relocation of Tocopilla aftershocks

    Science.gov (United States)

    Fuenzalida, A.; Schurr, B.; Lancieri, M.; Madariaga, R. I.

    2011-12-01

    The 14 November, Mw 7.8 2007 Tocopilla earthquake broke the southern part of seismic gap of northern Chile. The earthquake broke a rupture area 130 km by 30km along the deep plate interface between the Nazca and South American plates.The aftershock of this event were very well recorded by the IPOC (GFZ-IPGP-DGF) and Task Force networks (GFZ). Since the IPOC network was installed before the main Tocopilla earthquake we could locate the first two weeks of aftershocks with low accuracy.The first two weeks of aftershocks were characterised by a strong seismicity in the southern area starting with two big events of Mw 6.8 and 6.3 one day after the Tocopilla earthquake. On 29 November 2007 a Task Force (TF) Network of 20 short period instruments was installed by the GFZ team in the area of the Mejillones Peninsula. On 16 December a large Mw 6.8 slab push event took place at the center of this network. This event broke the oceanic crust of the subducted Nazca plate.(see Ruiz and Madariaga, this meeting). We have analysed in detail the TF data from its installation to 20 December. Hypocentral locations of the sequence were computed by automatic identification of the aftershocks and careful hand made readings of the arrival times of P and S phases for each seismogram. In a first study, we used the the nonlinear location software,NonLinLoc of Anthony Lomax using both a 1D model proposed by Husen from the study of earlier events in the region and the 2D model proposed by Patzwall et al from seismic profiles across the Mejillones Peninsula. We find that aftershocks were located along a thin, clearly defined zone that we interpret as the plate interface. As expected events situated off-shore of the Mejillones peninsula are less well located by Nonlinloc although our results suggest that several of these events occurred above the plate interface in the South American wedge. In a second step we relocated 850 events using the HypoDD method of Waldhauser et al with time delays

  1. Surface control on contrasts in deformation between eastern and western margins of the Central Andes

    Science.gov (United States)

    Schlunegger, F.; Norton, K. P.

    2012-04-01

    enhanced orographic rainfall, which promotes thrusting and internal shortening. A fault-scale coupled erosion-deformation model also shows that low erosion rates and steep topographic angles would have forced a migration of deformation from the Western Escarpment to the eastern side. These findings illustrate the strong control of orographic precipitation on the deformation of the Central Andes. Kober, F. et al. Denudation rates and topography-driven rainfall threshold in northern Chile: multiple cosmogenic nuclide data and sediment budgets. Geomorphology 83, 97-120 (2007). Norton, K. & Schlunegger, F. Migrating deformation in the Central Andes from enhanced orographic rainfall. Nat. Commun. 2, 584 (2011). Safran, E. B et al. Erosion rates driven by channel network incision in the Bolivian Andes. Earth Surf. Process Landforms 30, 1007-1024 (2005).

  2. On the generation of coastal lows in central Chile

    International Nuclear Information System (INIS)

    Previous studies of the coastal-low occurrences in central Chile have been aimed at the formulation of a conceptual model to explain observed features in connection with applied studies. The most prominent weather pattern associated with CL occurrences, (type A), coincides with the onset of a warm, middle-troposphere ridge over central Chile, and a surface high over northern Argentina. The synoptic forcing of the low is related to weak frontal disturbances that travel equatorwards. They result in a thickening of the marine layer that becomes blocked by the coastal escarpment, at the time of the onset of the ridge aloft. The blocking of the stable air above the subsidence inversion by the Andes is also hypothesized. The analysis of the subsidence inversion, the geometry of the coastal and Andes mountain ranges, and a scale analysis of the non-dimensional governing equations for the generation of the coastal lows, following the approach of Reason and Steyn (1990); leads to the conclusion that both blocking actions are strong and persistent in central Chile. An interactive mechanism between the upper and lower blocking effects is postulated to explain the cyclonic vorticity and the initial steering of the coastal lows. The scale analysis of the governing equations for the propagation stage of the low suggests that, departing for the South African case, non-linearity is important here, and that solitary Kelvin waves could be expected. Theoretical phase propagation speeds and Rossby radii are found to range between 8 and 15 m s-1 and 100-250 km, respectively. The importance of strong southerly winds ahead of the low and weak winds at its trailing edge is also stressed, as another major departure from the coastal-low behaviour elsewhere. (author). 17 refs, 4 figs, 4 tabs

  3. Fault rupture process and strong ground motion simulation of the 2014/04/01 Northern Chile (Pisagua) earthquake (Mw8.2)

    Science.gov (United States)

    Pulido Hernandez, N. E.; Suzuki, W.; Aoi, S.

    2014-12-01

    A megathrust earthquake occurred in Northern Chile in April 1, 2014, 23:46 (UTC) (Mw 8.2), in a region that had not experienced a major earthquake since the great 1877 (~M8.6) event. This area had been already identified as a mature seismic gap with a strong interseismic coupling inferred from geodetic measurements (Chlieh et al., JGR, 2011 and Metois et al., GJI, 2013). We used 48 components of strong motion records belonging to the IPOC network in Northern Chile to investigate the source process of the M8.2 Pisagua earthquake. Acceleration waveforms were integrated to get velocities and filtered between 0.02 and 0.125 Hz. We assumed a single fault plane segment with an area of 180 km by 135 km, a strike of 357, and a dip of 18 degrees (GCMT). We set the starting point of rupture at the USGS hypocenter (19.610S, 70.769W, depth 25km), and employed a multi-time-window linear waveform inversion method (Hartzell and Heaton, BSSA, 1983), to derive the rupture process of the Pisagua earthquake. Our results show a slip model characterized by one large slip area (asperity) localized 50 km south of the epicenter, a peak slip of 10 m and a total seismic moment of 2.36 x 1021Nm (Mw 8.2). Fault rupture slowly propagated to the south in front of the main asperity for the initial 25 seconds, and broke it by producing a strong acceleration stage. The fault plane rupture velocity was in average 2.9 km/s. Our calculations show an average stress drop of 4.5MPa for the entire fault rupture area and 12MPa for the asperity area. We simulated the near-source strong ground motion records in a broad frequency band (0.1 ~ 20 Hz), to investigate a possible multi-frequency fault rupture process as the one observed in recent mega-thrust earthquakes such as the 2011 Tohoku-oki (M9.0). Acknowledgments Strong motion data was kindly provided by Chile University as well as the IPOC (Integrated Plate boundary Observatory Chile).

  4. Future Temperatures and Precipitations in the Arid Northern-Central Chile: A Multi-Model Downscaling Approach

    Science.gov (United States)

    Souvignet, M.; Heinrich, J.

    2010-03-01

    Downscaling of global climate outputs is necessary to transfer projections of potential climate change scenarios to local levels. This is of special interest to dry mountainous areas, which are particularly vulnerable to climate change due to risks of reduced freshwater availability. These areas play a key role for hydrology since they usually receive the highest local precipitation rates stored in form of snow and glaciers. In the central-northern Chile (Norte Chico, 26-33ºS), where agriculture still serves as a backbone of the economy as well as ensures the well being of people, the knowledge of water resources availability is essential. The region is characterised by a semiarid climate with a mean annual precipitation inferior to 100mm. Moreover, the local climate is also highly influenced by the ENSO phenomenon, which accounts for the strong inter-annual variability in precipitation patterns. Although historical and spatially extensive precipitation data in the headwaters of the basins in this region are not readily available, records at coastal stations show worrisome trends. For instance, the average precipitation in La Serena, the most important city located in the Coquimbo Region, has decreased dramatically in the past 100 years. The 30-year monthly average has decreased from 170 mm in the early 20th century to values less than 80 mm nowadays. Climate Change is expected to strengthen this pattern in the region, and therefore strongly influence local hydrological patterns. The objectives of this study are i) to develop climate change scenarios (2046-2099) for the Norte Chico using multi-model predictions in terms of temperatures and precipitations, and ii) to compare the efficiency of two downscaling techniques in arid mountainous regions. In addition, this study aims at iii) providing decision makers with sound analysis of potential impact of Climate Change on streamflow in the region. For the present study, future local climate scenarios were developed

  5. The 2007 Tocopilla earthquake and its aftershock sequence - A subduction zone earthquake at the edge of the northern Chile seimic gap

    Science.gov (United States)

    Eggert, S.; Sobiesiak, M.; Shirzaei, M.

    2010-12-01

    On 14 November 2007 a large Mw 7.7 earthquake occurred in the region of Tocopilla in Northern Chile. The earthquake took place in the southern end of the Northern Chile seismic gap which is supposed to be at the end of its seismic cycle. Studying the event and its aftershock sequence will provide closer insight into the behavior of a subduction zone earthquake at the edge of a subduction zone segment. We present a comprehensive study of the rupture area combining seismic and geodetic data. The aftershock sequence following the earthquake was very well recorded by a local seismic network of 34 short period and broad band stations. The spatial distribution of the aftershock sequence shows a concentration of aftershocks around the north-western part of the Mejillones Peninsula and along the coast up to the Río Loa. The distribution into depth shows that the majority of the hypocenters are located along the subduction interface, reaching down to ~ 50 km depth. In the western part, the aftershock sequence splits into two branches, one heading towards the trench, the other bending into the crust in front of the Mejillones Peninsula. These seismic observations lead to the conclusion that the fault rupture propagated towards the south-west with a fault plane of about 150 km length leaving the shallow part in the north west probably unbroken. To better understand the behavior of the aftershock distribution we model the Coulomb stress transfer along the fault plane. The results show that stresses are increased in the southern part of the rupture area where we find a high concentration of aftershocks. This is consistent with the calculated energy release that shows two main patches along the plate interface rupturing from north to south. The 2007 Tocopilla earthquake is the first large event that occurred inside the Northern Chile seismic gap since the 1877 Iquique event. The rupture process stopped underneath the Mejillones Peninsula, a proposed segment boundary along the

  6. Seasonal and geographical variability in some trace elements of Pacific oysters (Crassostrea Gigas) cultured in two different bays of Northern Chile

    International Nuclear Information System (INIS)

    Chile has approximately 4,500 kilometers of continental coastline on the Pacific Ocean. It is therefore in a favorable position to develop fishing activities, since its waters contain a great variety of marine resources, namely, fish, shellfish and seaweeds. Fishing in Chile plays an important role in production. Metal contamination of the marine ecosystem is a pervasive and worldwide problem. Consequently, seafood consuming and exporting countries have gradually increased the need to improve the quality of their products in order to meet the required standards. In turn, this implies the need to adopt more efficient methods to analyze these resources by carrying out studies that will provide greater integral knowledge on the levels of essential and toxic trace elements found in seafood. In the present study, seasonal and geographical variability of some trace elements content of Pacific Oysters (Crassostrea Gigas) cultured, greatly demanded on the international market, are investigated. Samples for the analysis were collected from two different bays of Northern Chile, where heavy-metal pollution is already recognized as a problem. The trace elements content of this mollusk was studied at monthly intervals for 12 months (September 1987-August 1988). The determination of Cu was carried out using radiochemical neutron activation analysis and the other trace elements like Cd, As, Br, Na, Se, Cr, Fe, Zn and Co, were determined through neutron activation analysis in its purely instrumental form. NBS Standard Reference Materials were used to determine the accuracy of both methods. Significant differences were found comparing the content of copper and cadmium at the different seasons and locations of capture

  7. La Familia Trochidae (Mollusca: Gastropoda en el norte de Chile: consideraciones ecológicas y taxonómicas The trochidae family (Mollusca : Gastropoda in northern Chile: taxonomic and ecological considerations

    Directory of Open Access Journals (Sweden)

    DAVID VELIZ

    2000-12-01

    Full Text Available Este estudio describe la diversidad, y la distribución latitudinal y batimétrica de los caracoles de la Familia Trochidae en el norte de Chile, mediante muestreos intermareales y submareales someros, realizados entre 1996 y 1999 entre Arica (18º S y Los Vilos (31º S, y de muestras de profundidad provenientes de la pesca de arrastre del camarón nylon, Heterocarpus reedi. En el norte de Chile, la Familia Trochidae está representada por cuatro géneros: Tegula y Diloma de distribución intermareal y submareal somero hasta los 20 m de profundidad, y Bathybembix y Calliostoma presentes en profundidades superiores a los 200 m. El género Tegula tiene seis especies (T. quadricostata, T. luctuosa, T. ignota, T. atra, T. tridentata y T. euryomphala distribuídas en sustratos rocosos intermareales y submarales someros. El género Diloma está representado por una especie, D. nigerrima, de distribución intermareal hasta pocos metros de profundidad. El género Calliostoma tiene dos especies C. chilena y C. delli, las que se distribuyen entre 200 y 750 m de profundidad. Finalmente, el género Bathybembix está representado por B. humboldti y B. macdonaldi distribuídas entre 200 y 1480 m de profundidad. Esta segregación batimétrica parece estar relacionada a las estrategias alimentarias de cada uno de los géneros de la familia Trochidae. Diloma y Tegula son herbívoros, las especies del género Bathybembix son alimentadoras de depósito y las de Calliostoma son carnívorasThis study reveals the diversity, and the bathimetric and latitudinal distribution of the snails of the Trochidae family members in northern Chile, throughout the analysis of all Trochidae gastropods entailed in intertidal and subtidal (from the `camarón naylon' fishery samples collected during 1996 and 1999 between Arica (ca 18º S and Los Vilos (ca 31º S. The Trochidae family in northern Chile have four genus: Tegula and Diloma that are distributed on intertidal and shallow

  8. First record of folivory on a newly documented host plant for the little known geometrid moth Eupithecia yubitzae Vargas & Parra (Lepidoptera, Geometridae in northern Chile

    Directory of Open Access Journals (Sweden)

    Héctor A. Vargas

    2015-06-01

    Full Text Available The native tree Schinus molle (Anacardiacae is reported for the first time as a host plant for larvae of the little known geometrid moth Eupithecia yubitzae Vargas & Parra (Lepidoptera, Geometridae in the Atacama Desert of northern Chile, based on morphology and DNA barcodes. This discovery importantly expands the host range of E. yubitzae, as previous records were restricted to Fabaceae trees. Larvae were previously known as florivorous, while these were found to be folivorous on S. molle. Furthermore, host-associated cryptic larval polychromatism was detected, as larvae collected on S. molle were found to be mostly pale green, contrasting with the dark yellow ground color of the larvae typically collected on fabaceous host plants.

  9. First record of Cymatium keenae Beu, 1970 (Mollusca: Ranellidae) from Antofagasta Bay, northern Chile, in connection with El Niño events

    Science.gov (United States)

    Ashton, Tom; Riascos, Jose M.; Pacheco, Aldo

    2008-03-01

    Cymatium ( Monoplex) keenae Beu, 1970, the neopolitan triton, is a Ranellidae predator distributed in tropical and subtropical waters. In this study we report this species for the first time in Antofagasta Bay, northern Chile. Adult specimens have been found since June 2003 at depths ranging from 5 to 15 m in La Rinconada Marine Reserve (23°28'18″S, 70°30'46″W) in Antofagasta Bay, near a scallop farming facility. The present findings clearly extend the geographic range of C. keenae, which previously had been reported from La Paz, Gulf of California (Mexico) to Galápagos Islands (Ecuador) in the SE Pacific. Previous evidence strongly suggests that the intrusion of this tropical immigrant can be related to warm El Niño episodes. We analyze the key role of the oceanographic characteristics of Antofagasta Bay as potential temporal refuge for this species.

  10. Long-term denudation rates from the Central Andes (Chile) estimated from a digital elevation model using the black top hat function and inverse distance weighting : implications for the neogene climate of the Atacama Desert

    OpenAIRE

    Riquelme, R.; Darrozes, J; Maire, E.; Hérail, Gérard; J. C. Soula

    2008-01-01

    A methodology for determining long-term denudation rates from morphologic markers in a Digital Elevation Model (DEM) is checked by a comparative study of two drainage basins in the Precordillera of the Central Andes. In both cases the initial configuration of an incised pediment surface has been restored by using two different methods: the Black Top Hat (BTH) function and the Inverse Distance Weighting (IDW) interpolation. Where vertical incision and hillslope erosion are recorded, the 1DW ap...

  11. Inference of small-scale Vp/Vs ratio along the rupture area of the Tocopilla earthquake, Northern Chile (Mw 7.7, 14/11/2007)

    Science.gov (United States)

    Tilmann, F. J.; Palo, M.; Schurr, B.

    2014-12-01

    We have inferred the Vp/Vs ratio along the segment of the Peru-Chile subduction margin corresponding to the rupture area of the Tocopilla earthquake (TE, Mw 7.7, 14/11/2007). This event nucleated in Northern Chile and broke the southern ~100 km of the ~500 km Northern Chile Southern Peru seismic gap, which had not seen an earthquake of this magnitude since the M~9 event of 1877. TE activated two main co-seismic slip patches: one around the epicenter and another north-east of the Mejillones Peninsula. We have applied the Lin and Shearer approach [1] to the aftershock sequence of TE. In this approach, the relative time shift between the S phases of a pair of nearby events at one station are plotted as function of the time shift between the P phases of the same pair. The process is repeated for a set of events. If the events are close enough to assume a uniform local Vp/Vs and the P-reciprocal wavefront can be approximated as planar, the points lay on a line, whose slope is an estimation of the local Vp/Vs. The technique is extended to a set of stations demeaning the time shifts from each pair of events. The time shifts are inferred maximizing the cross-correlation function between the event pairs. The technique has been applied to clusters of events sharing similar waveforms and spatially clustered hypocentres. We have adopted a robust linear L2 regression and have assigned a statistical error to the best fit. Most clusters are identified within a sub-vertical branch of the subduction interface hosting a major aftershock (Michilla earthquake, 16/12/2007, Ml 6.8) and its aftershocks. This branch falls inside the subducted Nazca Plate at depths of 40-50 km, north-east of the Mejillones Peninsula, and shows Vp/Vs mostly in the range 1.8-1.9. Clusters close to the Mejillones Peninsula and to the epicenter displays Vp/Vs around 1.7 and 1.8, respectively. References [1] - Lin, G., & Shearer, P. (2007). Estimating local Vp/Vs ratios within similar earthquake clusters

  12. "Un devorador de su propia especie". Violencia, justicia y cultura popular en Santa Rosa de los Andes: las formas de la autoridad a los ojos de un peón de oficio matador, Chile 1805

    OpenAIRE

    Daniel Moreno Bazaes

    2016-01-01

    A través del análisis microhistórico del proceso judicial seguido por las autoridades de la villa de Santa Rosa de Los Andes e intervenido por la Real Audiencia de Santiago contra Juan Francisco Varas, “peón-gañan” de la hacienda de Llay-Llay, responsable de a lo menos seis homicidios y otros tantos crímenes que atentaron contra el orden local y el gobierno civil, se pretende dar cuenta de los pormenores de la organización social en el Valle del Aconcagua a fines del siglo XVIII y durante los...

  13. Las infracomunidades de parásitos de dos especies de Scartichthys (Pisces: Blenniidae en localidades cercanas del norte de Chile Parasite infracommunities of two blennid species, Scartichthys (Pisces: Blenniidae, at nearby localities off northern Chile

    Directory of Open Access Journals (Sweden)

    KAREN FLORES

    2009-03-01

    Full Text Available Se comparan las infracomunidades de parásitos de dos especies congenéricas y simpátridas de peces marinos: Scartichthys viridis (Valenciennes 1836 y Scartichthys gigas (Steindachner 1876 (Pisces: Blenniidae, en tres localidades del intermareal rocoso de Iquique (20°32' S, 70°11' O, norte de Chile, separadas por no más de 6 km, con muestras recolectadas entre agosto y septiembre de 2005. El objetivo fue evaluar la variabilidad de la riqueza, abundancia, diversidad, dominancia y composición en una escala espacial y temporal reducida. En total, se recolectaron 2.110 individuos parásitos en los 134 hospedadores examinados, los que pertenecían a 14 taxa. Se encontró una gran similitud en la composición y en las propiedades agregadas de las infracomunidades, tanto entre especies de hospedadores como entre sitios de estudio. Se interpreta que las condiciones ambientales, los factores ecológicos como el uso del habitat y de los recursos alimentarios, y los factores evolutivos como el alto grado de parentesco de estas especies de Scartichthys, son las principales influencias en la alta similitud parasitaria encontrada.The infracommunities of metazoan parasites in two congeneric and sympatric marine fish species, Scartichthys viridis (Valenciennes 1836 and Scartichthys gigas (Steindachner 1876, were studied and compared between three localities of the intertidal rocky shore off the coast of northern Chile, near Iquique (20°32' S, 70°11' W, which were separated by no more than 6 km. Samples were collected between August and September 2005. The goal of this study was to assess the variability in richness, abundance, diversity, dominance and parasite composition between close localities sampled within a short period. In all, 2,110 parasite individuals were collected from the 134 hosts examined, and 14 parasite taxa were identified. There was great similarity in the aggregated and compositional properties of the infracommunities, both between

  14. Andes 1997 Gravity Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Central Andes gravity data (6,151 records) were compiled by Professor Gotze and the MIGRA Group. This data base was received in April, 1997. Principal gravity...

  15. History of Lake Andes

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Information about the history and management of Lake Andes is compiled in this report. It is intended to help future refuge managers become acquainted with the...

  16. Paleohydrologic evolution and geochemical dynamics of cumulative supergene metal enrichment at La Escondida, Atacama Desert, northern Chile

    Science.gov (United States)

    Alpers, C.N.; Brimhall, G.H.

    1989-01-01

    Quantitative limonite mapping within the leached capping of the porphyry copper deposit at La Escondida, Chile, permits reconstruction of the paleohydrologic and chemical evolution of a well-developed supergene ore-forming system. The mineralogy, textures, and relative abundance of supergene limonite minerals (hematite, goethite, and jarosite) are used to reconstruct the former ratio of pyrite to chalcocite and the preoxidation copper grade based on empirical limonite sulfide correlations. Evidence for cumulative downward enrichment in vertical profiles through leached capping allows quantitative analysis of chemical mass balance in dynamic supergene systems. Slopes of linear regressions for profiles of reconstructed enriched copper grades vs. depth indicate lateral fluxes into or out of a given vertical profile. -from Authors

  17. Numerical model to evaluate the mitigation strategies to combat desertification and drought in the arid land of northern Chile.

    Science.gov (United States)

    Salinas, Carla; Mendieta, Jon

    2014-05-01

    Desertification is considered a global environmental problem with political and socioeconomic implications. Desertification, exacerbated by climate change, is the largest environmental problem in Chile affecting almost two third of the national territory. This study takes place in a latitudinal gradient of the north-central Chilean drylands, where desertification is a threat to agriculture, livestock and forestry (ALF). The critical areas or priority areas for combating desertification are the northernmost areas of the region under study. In the context of the United Nations Convention to Combat Desertification (UNCCD) and the implementation of the Chilean National Action Programme (NAP), the country is conducting policies and investing in mitigation strategies to combat land degradation and desertification. The main objective of this study is the development of an integrative methodological approach using real data of the territorial and socioeconomic indicators. With the proposed methodology we assess the impact of the mitigation and land degradation strategies supported by the ALF promotion agencies in the fight against desertification, projecting different scenarios of change. The data were collected in 2008 in Santiago, Chile. The results of the Principal Component Analysis (PCA) suggest that technical irrigation and the improvement of grasslands and pastures play an important role in the fight against desertification. The results of the model projections are consistent, suggesting that the efforts of the ALF promotion agencies have a positive impact in fighting desertification. Inaction of ALF mitigation strategies would increase desertification. This methodological approach, performed with real data, can also determine the main causes of desertification in such a complex area as the studied one, where we can find the desert itself, and its desertification endangered valleys, the Andean plateau, the transitional area and the southern regions. Ii is also a

  18. Tarapacá intermediate-depth earthquake (Mw 7.7, 2005, northern Chile): A slab-pull event with horizontal fault plane constrained from seismologic and geodetic observations

    OpenAIRE

    Peyrat, S.; J. Campos; De Chabalier, Jean-Bernard; Bonvalot, S.; Bouin, M.-P.; Legrand, D; Nercessian, A; Charade, O.; Patau, G.; Clévédé, E; Kausel, E.; BERNARD, Patrick; Vilotte, J.-P; Perez, A.

    2006-01-01

    International audience [1] A large (Mw 7.7) intermediate-depth earthquake occurred on 13 June 2005 in the Tarapacá region of the northern Chile seismic gap. Source parameters are inferred from teleseismic broadbands, strong motions, GPS and InSAR data. Relocated hypocenter is found at $98 km depth within the subducting slab. The 21-days aftershock distribution, constrained by a postseismic temporary array, indicates a sub-horizontal fault plane lying between the planes of the double seismi...

  19. Identification of aquifer limits inside an Andean Piedmont (between 19,5°S and 20°S - Northern Chile) with TDEM and gauging methods.

    Science.gov (United States)

    Viguier, Benoit; Jourde, Hervé; Leonardi, Véronique; Moya, Claudio; Líra, Elias; Yáñez, Gonzalo; Maringue, José; García-Pérez, Tiaren; Lictevout, Elisabeth

    2016-04-01

    In times of brutal climate changes and water scarcity in arid areas, the management of water resource has become a major issue. In this aim, several studies attempted to quantify the aquifer recharge and hydrodynamic processes. However, the quality of many studies depends on the characterization of aquifer boundaries. In arid areas, the amount of observation points (e.g. wells) and their spatial distribution constrain the understanding of aquifer boundaries spatial variations. In this study, we propose a methodology to characterize both water table level and boundaries of aquifer in such areas where the observation points do not exist. The Andean Piedmont (between 19,5°S and 20°S - Northern Chile) is located in the Pampa del Tamarugal Central Depression and is bounded respectively at the westside and the eastside by the Coastal Cordillera (1100 m a.s.l) and the Precordillera mountain range (4500 m a.s.l). The piedmont and the basin floor are composed of the late-Cenozoic alluvial deposits (hundred meters thick) which contain the Pampa del Tamarugal aquifer. Due to the hyperarid context, this regional aquifer is one of the main strategic groundwater resources in Northern Chile. This aquifer is mainly unconfined and the electrical conductivity of groundwater varies around 3000 μS/cm in the study area. The analysis of resistivity variation with depth, acquired by Time Domain Electromagnetic (TDEM) method in various points inside the piedmont, allow identifying a continuous resistivity contrast (from ≥ 100-40 Ω.m to ≤ 10 Ω.m) that varies over the study area. This continuous resistivity contrast is assumed to be related to the water table of the unconfined aquifer rather than to a lithology contrast. After validation of the observations, a piezometric map was constructed using both the available hydrogeological information and the TDEM results. In the piedmont, river sink were identified; these zones where surface water sinks are correlated with the resistivity

  20. Eocene to Pleistocene lithostratigraphy, chronostratigraphy and tectono-sedimentary evolution of the Calama Basin, northern Chile Litoestratigrafía, cronoestratigrafía durante el Eoceno al Pleistoceno y evolución tectono-sedimentaria de la Cuenca de Calama, norte de Chile

    OpenAIRE

    Geoffrey May; Adrian J Hartley; Guillermo Chong; Fin Stuart; Peter Turner; Stephanie J Kape

    2005-01-01

    New 40Ar/39Ar radiometric, sedimentological and structural data from post-Paleocene sedimentary strata in the Calama Basin, northern Chile suggest that the established lithostratigraphy of the basin-fill requires revision. A new lithostratigraphic scheme for the Eocene-Pleistocene stratigraphy of the Calama Basin is proposed here. The key features of this scheme are that the existing Calama Formation is retained although the age of the formation is redefined as (?Lower) Eocene to (?)Lower Mio...

  1. Distribution of chemical elements in calc-alkaline igneous rocks, soils, sediments and tailings deposits in northern central Chile

    Science.gov (United States)

    Oyarzún, Jorge; Oyarzun, Roberto; Lillo, Javier; Higueras, Pablo; Maturana, Hugo; Oyarzún, Ricardo

    2016-08-01

    This study follows the paths of 32 chemical elements in the arid to semi-arid realm of the western Andes, between 27° and 33° S, a region hosting important ore deposits and mining operations. The study encompasses igneous rocks, soils, river and stream sediments, and tailings deposits. The chemical elements have been grouped according to the Goldschmidt classification, and their concentrations in each compartment are confronted with their expected contents for different rock types based on geochemical affinities and the geologic and metallogenic setting. Also, the element behavior during rock weathering and fluvial transport is here interpreted in terms of the ionic potentials and solubility products. The results highlight the similarity between the chemical composition of the andesites and that of the average Continental Crust, except for the higher V and Mn contents of the former, and their depletion in Mg, Ni, and Cr. The geochemical behavior of the elements in the different compartments (rocks, soils, sediments and tailings) is highly consistent with the mobility expected from their ionic potentials, their sulfates and carbonates solubility products, and their affinities for Fe and Mn hydroxides. From an environmental perspective, the low solubility of Cu, Zn, and Pb due to climatic, chemical, and mineralogical factors reduces the pollution risks related to their high to extremely high contents in source materials (e.g., rocks, altered zones, tailings). Besides, the complex oxyanions of arsenic get bound by colloidal particles of Fe-hydroxides and oxyhydroxides (e.g., goethite), thus becoming incorporated to the fine sediment fraction in the stream sediments.

  2. Environmental changes in two lakes of Northern Patagonia (Chile): A 1000 yr reconstruction based on pollen and charcoal

    Science.gov (United States)

    Nicole, Vargas; Laura, Torres; Alberto, Araneda; Fabiola, Cruces; Fernando, Torrejón; Denisse, Alvarez; G, Bizama; Nathalie, Fagel; Roberto, Urrutia

    2010-05-01

    We aim to reconstruct the environmental changes experimented in Patagonian ecosystems during the last 1000 years. We analyze sediment cores from two lakes (Thompson and Burgos), located in Aysen Region, Southern Chile. The samples were obtained using a gravity corer and sampled at intervals of 1 cm to 30 cm depth and every 5 cm until the end of the core. Thompson lake sediment core was sampled every 5 cm. Age model is based on radiocarbon datings on bulk sediments and macroremains. In Burgos lake we evidence two main climatic changes. A wet period between 876-1444 AD is marked by the presence of Pteridophytes. A colder and dryer period is then evidenced by an increase of Berberis sp between 1444 and 1656 AD. From 1834 AD to Present the sediment record is mainly affected by human activities. High concentrations of carbon particles and a sharp change in pollen assemblage (increase of Poaceae, decrease of Nothofagus dombeyi-Type) are indicators of two large fire events. The lacustrine sediment of Thompson is characterized by a wetter period, between 874 - 1168 AD, with abundance of Pteridophytes. Then from 1168 AD to Present the environmental conditions of the watershed were characterized by lower ferns and fire events. Two major fires were evidenced between 1850 AD and Present. Like in Burgos they are marked by major changes in plant associations (sharp increase in Poaceae, drastic loss of Nothofagus dombeyi-Type). Wet periods identified in both lakes at the base of the sediment record could correspond to manifestations of a warm climate anomaly like the Medieval Warm Period. The dry and cold period, especially obvious in the Burgos record, could be associated to a cold climate anomaly. Finally the great changes in vegetation that occurred from the year ~ 1830 in the basin of the two lakes were directly related to human activities (forest cutting) developed during the ninetheenth and twentieth centuries. This research is funded by both Chilean and Belgian projects

  3. Timing of the magmatism of the paleo-Pacific border of Gondwana: U-Pb geochronology of Late Paleozoic to Early Mesozoic igneous rocks of the north Chilean Andes between 20o and 31oS

    International Nuclear Information System (INIS)

    U-Pb zircon geochronological data provide record of about 130 Ma of igneous activity in the Andes of northern Chile, which extended episodically from the latest Early Carboniferous to Early Jurassic (328-194 Ma). The overall U-Pb data show that volcanism and plutonism were essentially synchronous and major episodes of igneous activity developed during the Late Carboniferous to Mid-Permian (310 to 260 Ma) and from Late Permian to Late Triassic (255-205 Ma), with less prominent episodes in the mid-Carboniferous (330 to 320 Ma), and Early Jurassic (200-190 Ma). Thus, from the Carboniferous to the Early Triassic dominantly silicic magmatism developed along the Chilean segment of the southwestern border of Gondwana supercontinent. Further magmatism developed during the Mid-Late Triassic (250-194 Ma) was bimodal and synchronous with rift-related, continental and/or marine sedimentary strata related to the early stages of break-up of Gondwana. Most of the silicic volcanic rocks of the Precordillera and Domeyko Cordillera of northern Chile (21o 30o to 25o30oS) are older than the silicic rocks assigned to the Choiyoi succession in Argentina, being instead equivalent in age to Carboniferous to Early Permian marine sedimentary sequences present in the eastern Argentinean foreland. On the other hand, silicic volcanic successions exposed in the easternmost part of northern Chile are equivalent in age to the Choiyoi succession of the San Rafael Block of Argentina. An eastward expansion or migration of the volcanism during the Mid-Permian to Early Triassic is inferred, interpretation that is consistent with expansion of the volcanism at that time in Argentina. The timing of the Late Paleozoic to Early Jurassic magmatism is coincident with that of the Andes of Peru and of western Argentina according to the available U-Pb data, revealing a rather consistent evolution in time of the magmatism along the southwestern, paleo-Pacific border of Gondwana

  4. Grown-out of seeds of the taquilla clam Mulinia edulis (King & Broderip, 1832 in the subtidal zone in northern Chile and in the intertidal zone in southern Chile Engorda de semillas de la almeja taquilla Mulinia edulis (King & Broderip, 1832 en la zona submareal en el norte y en la zona intermareal en el sur de Chile

    Directory of Open Access Journals (Sweden)

    Alejandro Abarca

    2012-09-01

    Full Text Available Seeds of the clam Mulinia edulis produced in a hatchery were grown in bottom cages in the subtidal zone of Tongoy Bay (northern Chile and in the intertidal zone of Chullec (Chiloé Island, southern Chile, to compare the growth and survival of small and large seeds of the same production in different environments and latitudes. Seeds were shipped twice to Chullec, once in summer and once in winter. Previous experiments with seed transportation (14.2 ± 2.4 mm showed that they are able to survive more than 24 h out of water. The growth rate of both large and small seeds was greater in Tongoy than in Chullec, reaching maxima of 1.24 mm month-1 in the small seeds of Tongoy and 1.06 mm month-1 in the same group in Chullec. The growth rates obtained for M. edulis were similar to those described for other cultured clams. Seeds grown in Chullec presented a significantly greater weight by size than the seeds grown in Tongoy. Survival after 12 months was 38% and 88% in Tongoy and 19.4% and 37.3% in Chullec for small and large seeds, respectively. Seeds produced in hatcheries are able to withstand long travel (1,360 km and grow in the intertidal zone of southern Chile, where the operation of the culture is simple and cheap. The growth curve presents an inflection point around 20 mm length, probably related to the age at sexual maturity. Growing out seeds in the intertidal zone in southern Chile is seen as a new activity for artisanal fishermen.Semillas de la almeja Mulinia edulis producidas en el Hatchery de Pesquera San José (Tongoy fueron engordadas en sistemas de fondo en la zona submareal de bahía Tongoy e intermareal en Chullec (Chiloé, para comparar el crecimiento y la supervivencia de semillas pequenas y grandes de una misma producción en diferentes ambientes y latitudes. Se realizaron dos envíos de semillas a Chullec, uno en verano y otro en invierno. Experimentos de simulación del transporte de semillas (14,2 ± 2,4 mm muestran que

  5. Performance model to assist solar thermal power plant siting in northern Chile based on backup fuel consumption

    Energy Technology Data Exchange (ETDEWEB)

    Larrain, Teresita; Escobar, Rodrigo; Vergara, Julio [Departamento de Ingenieria Mecanica y Metalurgica, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860, Macul, Santiago (Chile)

    2010-08-15

    In response to environmental awareness, Chile introduced sustainability goals in its electricity law. Power producers must deliver 5% from renewable sources by 2010 and 10% by 2024. The Chilean desert has a large available surface with one of the highest radiation levels and clearest skies in the World. These factors imply that solar power is an option for this task. However, a commercial plant requires a fossil fuel system to backup the sunlight intermittency. The authors developed a thermodynamical model to estimate the backup fraction needed in a 100 MW hybrid -solar-fossil- parabolic trough power plant. This paper presents the model aiming to predicting the performance and exploring its usefulness in assisting site selection among four locations. Since solar radiation data are only available in a monthly average, we introduced two approaches to feed the model. One data set provided an average month with identical days throughout and the other one considered an artificial month of different daylight profiles on an hourly basis for the same monthly average. We recommend a best plant location based on minimum fossil fuel backup, contributing to optimal siting from the energy perspective. Utilities will refine their policy goals more closely when a precise solar energy data set becomes available. (author)

  6. Thermophysical properties and corrosion characterization of low cost lithium containing nitrate salts produced in northern Chile for thermal energy storage

    Science.gov (United States)

    Fernández, Ángel G.; Gomez, Judith C.; Galleguillos, Hector; Fuentealba, Edward

    2016-05-01

    In recent years, lithium containing salts have been studied for thermal energy storage (TES) systems applications, because of their optimal thermophysical properties. In solar power plants, lithium is seen as a way to improve the properties of molten salts used today. Lithium nitrate is a good candidate for sensible heat storage, due to its ability to increase the salt mixture's working temperature range. In the present research, thermophysical properties characterization of lithium nitrate containing salts, produced in Chile, have been carried out. Corrosion evaluations of carbon and low chromium steels were performed at 390°C for 1000 hours. Thermophysical properties of the salt mixtures, such as thermal stability and heat capacity, were measured before and after corrosion tests. Chemical composition of the salts was also determined and an estimation of Chilean production costs is reported. Results showed that purity, thermal stability and heat capacity of the salts were reduced, caused by partial thermal decomposition and incorporation of corrosion products from the steel.

  7. Thermophysical Properties and Corrosion Characterization of Low Cost Lithium Containing Nitrate Salts Produced in Northern Chile for Thermal Energy Storage

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, Angel G.; Gomez, Judith C.; Galleguillos, Hector; Fuentealba, Edward

    2016-05-31

    In recent years, lithium containing salts have been studied for thermal energy storage (TES) systems applications, because of their optimal thermophysical properties. In solar power plants, lithium is seen as a way to improve the properties of molten salts used today. Lithium nitrate is a good candidate for sensible heat storage, due to its ability to increase the salt mixture's working temperature range. In the present research, thermophysical properties characterization of lithium nitrate containing salts, produced in Chile, have been carried out. Corrosion evaluations of carbon and low chromium steels were performed at 390 degrees C for 1000 hours. Thermophysical properties of the salt mixtures, such as thermal stability and heat capacity, were measured before and after corrosion tests. Chemical composition of the salts was also determined and an estimation of Chilean production costs is reported. Results showed that purity, thermal stability and heat capacity of the salts were reduced, caused by partial thermal decomposition and incorporation of corrosion products from the steel.

  8. Occurrence of arsenic species in algae and freshwater plants of an extreme arid region in northern Chile, the Loa River Basin.

    Science.gov (United States)

    Pell, Albert; Márquez, Anna; López-Sánchez, José Fermín; Rubio, Roser; Barbero, Mercedes; Stegen, Susana; Queirolo, Fabrizio; Díaz-Palma, Paula

    2013-01-01

    This study reports data on arsenic speciation in two green algae species (Cladophora sp. and Chara sp.) and in five aquatic plants (Azolla sp., Myriophyllum aquaticum, Phylloscirpus cf. desserticola, Potamogeton pectinatus, Ruppia filifolia and Zannichellia palustris) from the Loa River Basin in the Atacama Desert (northern Chile). Arsenic content was measured by Mass spectrometry coupled with Inductively Coupled Plasma (ICP-MS), after acidic digestion. Liquid chromatography coupled to ICP-MS was used for arsenic speciation, using both anionic and cationic chromatographic exchange systems. Inorganic arsenic compounds were the main arsenic species measured in all samples. The main arsenic species in the extracts of freshwater algae and plants were arsenite and arsenate, whereas glycerol-arsenosugar (gly-sug), dimethylarsinic acid (DMA) and methylarsonic acid (MA) were present only as minor constituents. Of the samples studied, algae species accumulated more arsenic than aquatic plants. Total arsenic content ranged from 182 to 11100 and from 20 to 248 mg As kg(-1) (d.w.) in algae and freshwater plants, respectively. In comparison with As concentration in water samples, there was hyper-accumulation (>0.1% d.w.) in Cladophora sp. PMID:22981629

  9. Macaria mirthae Vargas et al (Lepidoptera: Geometridae): Confirmation of the Use of an Invasive Host Plant in the Northern Atacama Desert of Chile Based on DNA Barcodes.

    Science.gov (United States)

    Rivera-Cabello, D; Huanca-Mamani, W; Vargas, H A

    2015-08-01

    Macaria mirthae Vargas et al (Lepidoptera: Geometridae) is a geometrid moth native to the northern Atacama Desert of Chile. Its oligophagous larvae are associated with native hosts of the plant family Fabaceae, the most important of which is Acacia macracantha. The invasive tree Leucaena leucocephala (Fabaceae) was recently recorded as a host plant for M. mirthae based on morphology. The taxonomic status of larvae collected on A. macracantha and L. leucocephala was assessed using sequences of the DNA barcode fragment of the cytochrome c oxidase subunit I (COI) gene. Genetic divergence between samples from the host plants was found to be 0%-0.8% (Kimura 2-parameter model). Neighbor-joining and maximum likelihood analyses were also performed, including additional barcode sequences of Neotropical geometrid moths from GenBank and BOLD databases. Sequences of the larvae from both host plants clustered in a single clade with high statistical support in both analyses. Based on these results, it is concluded that M. mirthae has effectively expanded its host range and its larvae are currently feeding on the exotic tree L. leucocephala. Additionally, the importance of this new host association in a highly disturbed habitat is briefly discussed in terms of the field biology of this native geometrid moth. PMID:26174961

  10. Evolución tectónica, paleogeográfica y metalogénica durante el Cenozoico en los Andes de Chile norte y central e implicaciones para las regiones adyacentes de Bolivia y Argentina

    OpenAIRE

    2009-01-01

    La orogenia incaica dio origen a un importante relieve en el Eoceno Medio, el que se concentró en el ámbito del arco magmático precedente, la Cordillera Incaica. Este relieve positivo de orientación NNE se extendió desde el sur de Perú hasta la región central de Chile y separó dos dominios paleogeográficos que tuvieron evoluciones diferentes durante el resto del Cenozoico. El dominio occidental se caracterizó por el predominio de procesos de erosión y sedimentación. En el dominio oriental tam...

  11. Preliminary re-evaluation of probabilistic seismic hazard assessment in Chile: from Arica to Taitao Peninsula

    Directory of Open Access Journals (Sweden)

    F. Leyton

    2009-12-01

    Full Text Available Chile is one of the most seismically active countries in the world; indeed, having witnessed very large earthquakes associated with high horizontal peak ground accelerations, the use of probabilistic hazard assessment is an important tool in any decision-making. In the present study, we review all the available information to improve the estimation of the probabilistic seismic hazard caused by two main sources: shallow interplate, thrust earthquakes and intermediate depth, intraplate earthquakes. Using previously defined seismic zones, we compute Gutenberg-Richter laws and, along with appropriate attenuation laws, revaluate the probabilistic seismic hazard assessments in Chile. We obtain expected horizontal peak ground acceleration with a 10% of probability of being exceeded in 50 years, reaching from 0.6 g up 1.0 g in the coast and between 0.4 g and 0.6 g towards the Andes Mountains, with larger values in Northern part of the country. The present study improves our knowledge of geological hazards in Chile, enabling the mitigation of important human and material losses due to large earthquakes in the future.

  12. Across and along arc geochemical variations in altered volcanic rocks: Evidence from mineral chemistry of Jurassic lavas in northern Chile, and tectonic implications

    Science.gov (United States)

    Rossel, Pablo; Oliveros, Verónica; Ducea, Mihai N.; Hernandez, Laura

    2015-12-01

    Postmagmatic processes mask the original whole-rock chemistry of most Mesozoic igneous rocks from the Andean arc and back-arc units preserved in Chile. Mineral assemblages corresponding to subgreenschist metamorphic facies and/or propylitic hydrothermal alteration are ubiquitous in volcanic and plutonic rocks, suggesting element mobility at macroscopic and microscopic scale. However, fresh primary phenocrysts of clinopyroxene and plagioclase do occur in some of the altered rocks. We use major and trace element chemistry of such mineral phases to infer the geochemical variations of four Jurassic arc and four back-arc units from northern Chile. Clinopyroxene belonging to rocks of the main arc and two units of the bark-arc are augites with low contents of HFSE and REE; they originated from melting of an asthenospheric mantle source. Clinopyroxenes from a third back-arc unit show typical OIB affinities, with high Ti and trace element contents and low Si. Trace elemental variations in clinopyroxenes from these arc and back-arc units suggest that olivine and clinopyroxene were the main fractionating phases during early stages of magma evolution. The last back-arc unit shows a broad spectrum of clinopyroxene compositions that includes depleted arc-like augite, high Al and high Sr-Ca diopside (adakite-like signature). The origin of these lavas is the result of melting of a mixture of depleted mantle plus Sr-rich sediments and subsequent high pressure fractionation of garnet. Thermobarometric calculations suggest that the Jurassic arc and back-arc magmatism had at least one crustal stagnation level where crystallization and fractionation took place, located at ca. ~ 8-15 km. The depth of this stagnation level is consistent with lower-middle crust boundary in extensional settings. Crystallization conditions calculated for high Al diopsides suggest a deeper stagnation level that is not consistent with a thinned back-arc continental crust. Thus minor garnet fractionation

  13. Evaluación del crecimiento del pulpo común Octopus mimus del norte de Chile alimentado con dietas formuladas Growth evaluation of octopus (Octopus mimus from northern Chile fed with formulated diets

    Directory of Open Access Journals (Sweden)

    Oscar Zúñiga

    2011-11-01

    Full Text Available Durante 57 días se comparó el crecimiento y sobreviviencia de pulpos juveniles Octopus mimus del norte de Chile alimentados con tres diferentes dietas: dos dietas húmedas (A y B aglutinadas con solución de gelatina embutidas en tripa de cordero y una dieta control (C natural. La dieta (A fue elaborada en base a una mezcla de filete triturado del pescado Cheilodactylus variegatus con harina de pellet para salmón, la dieta (B con pasta de almeja (Protothaca thaca mezclada con filete de Ch. variegatus y la dieta control consistió en el suministro de almejas frescas congeladas (C. Basado en un diseño experimental de medidas repetidas, los pulpos se mantuvieron individualmente en estanques de 70 L con circulación de agua de mar y aireación permanente. Los pulpos que consumieron la dieta B no experimentaron mortalidad y la dieta control C presentó mortalidad del 16,7%, sus crecimiento fueron similares (P > 0,05 con tasas de crecimiento absoluta (AGR de 7,0 ± 0,91 (g d-1 y 6,6 ± 1,10 (g d-1 respectivamente. Los pulpos alimentados con la dieta A registraron mortalidad de 33,3% y tasa de crecimiento absoluta negativa, AGR= -1,70 ± 0,37 (g d-1. La dieta A que contenía como ingrediente pellet para salmón molido como harina no tuvo una adecuada aceptación y los ejemplares experimentaron disminución de su peso. La dieta B preparada con gelatina de origen animal como aglutinante, no implicó un efecto negativo en la palatabilidad y aceptabilidad en comparación al control basada en almeja fresca congelada, incluso los organismos lograron crecimientos similares. Los resultados permitirán a futuro mejorar la calidad nutricional de dietas artificiales para maximizar el crecimiento de O. mimus en cautiverio.The growth and survival of juvenile octopus, Octopus mimus, from northern Chile, fed three different diets were analyze during 57 days. Two of the diets (A and B were wet diets stuffed in lamb gut with a gelatin solution, and the third (C was

  14. The low-grade Canal de las Montañas Shear Zone and its role in the tectonic emplacement of the Sarmiento Ophiolitic Complex and Late Cretaceous Patagonian Andes orogeny, Chile

    Science.gov (United States)

    Calderón, M.; Fosdick, J. C.; Warren, C.; Massonne, H.-J.; Fanning, C. M.; Cury, L. Fadel; Schwanethal, J.; Fonseca, P. E.; Galaz, G.; Gaytán, D.; Hervé, F.

    2012-02-01

    The Canal de las Montañas Shear Zone (CMSZ), southern Patagonian Andes (51-52°S), is a low-grade mylonite belt generated from felsic ignimbritic, pelitic and basaltic protoliths of the Late Jurassic-Early Cretaceous Rocas Verdes basin. The different types of rock fabrics across the CMSZ are thought to be associated with relatively intermediate and high strain conditions, characterized by the development of a narrow western belt of S-Ć-type mylonites and phyllonites interpreted as the metamorphic sole thrust of the Sarmiento Ophiolitic Complex. Highly strained rocks of the CMSZ display a reverse, continent-ward tectonic transport, with a minor dextral component of shearing. Transitional pumpellyite-actinolite and upper greenschist facies metamorphic conditions at ca. 5-6 kbar and 230-260 °C indicate that the primary shearing event occurred in a subduction zone setting. In-situ 40Ar/39Ar laserprobe chronology yielded ages of ca. 85 Ma on syntectonic phengite which are interpreted as representing cooling synchronous with mica crystallization during the main compressive deformational event. The 78-81 Ma U-Pb zircon crystallization ages of cross-cutting plutonic and hypabyssal rocks and 40Ar/39Ar amphibole age of ca.79 Ma from lamprophyric dikes within the fold-thrust belt constrain an upper age limit of the ophiolite tectonic emplacement deformation.

  15. Active tectonics of the Andes

    Science.gov (United States)

    Dewey, J. F.; Lamb, S. H.

    1992-04-01

    Nearly 90 mm a -1 of relative plate convergence is absorbed in the Andean plate-boundary zone. The pattern of active tectonics shows remarkable variations in the way in which the plate slip vector is partitioned into displacement and strain and the ways in which compatibility between different segments is solved. Along any traverse across the plate-boundary zone, the sum of relative velocities between points must equal the relative plate motion. We have developed a kinematic synthesis of displacement and strain partitioning in the Andes from 47°S to 5°N relevant for the last 5 Ma based upon: (1) relative plate motion deduced from oceanic circuits giving a roughly constant azimuth between 075 and 080; (2) moment tensor solutions for over 120 crustal earthquakes since 1960; (3) structural studies of deformed Plio-Pleistocene rocks; (4) topographic/geomorphic studies; (5) palaeomagnetic data; and (6) geodetic data. We recognize four neotectonic zones, with subzones and boundary transfer zones, that are partitioned in different ways. These zones are not coincident with the 'classic' zones defined by the presence or absence of a volcanic chain or differences in finite displacements and strains and tectonic form; the long-term segmentation and finite evolution of the Andes may not occur in constantly defined segments in space and time. In Segment 1 (47°-39°S), the slip vector is partitioned into roughly orthogonal Benioff Zone slip with large magnitude/large slip-surface earthquakes and both distributed dextral shear giving clockwise rotations of up to 50° and dextral slip in the curved Liquine-Ofqui Fault System giving 5°-10° of anticlockwise fore-arc rotation. In Segment 2 (39°-20°S), the slip vector is partitioned into Benioff Zone slip roughly parallel with the slip vector, Andean crustal shortening and a very small component of dextral slip, including that on the Atacama Fault System. Between 39° and 34°S, a cross-strike dextral transfer, which deflects

  16. Sr and Nd isotopic and trace element compositions of Quaternary volcanic centers of the southern Andes

    International Nuclear Information System (INIS)

    Isotopic compositions of samples from six Quaternary volcanoes located in the northern and southern extremities of the Southern Volcanic Zone (SVZ, 33-460S) of the Andes and from four centers in the Austral Volcanic Zone (AVZ, 49-540S) range for 87Sr/86Sr from 0.70280 to 0.70591 and for 143Nd/144Nd from 0.51314 to 0.51255. Basalts and basaltic andesites from three centers just north of the Chile Rise-Trench triple junction have 87Sr/86Sr, 143Nd/144Nd, La/Yb, Ba/La and Hf/Lu that lie within the relatively restricted ranges of the basic magmas erupted from the volcanic centers as far north as 350S in the SVZ of the Andes. The trace element and Sr and Nd isotopic characteristics of these magmas may be explained by source region contamination of subarc asthenosphere, with contaminants derived from subducted pelagic sediments and seawater-altered basalts by dehydration of subducted oceanic lithosphere. In the northern extremity of the SVZ between 330 and 340S, basaltic andesites and andesites have higher 87Sr/86Sr, Rb/Cs, and Hf/Lu, and lower 143Nd/144Nd than basalts and basaltic andesites erupted farther south in the SVZ, which suggests involvement of components derived from the continental crust. In the AVZ, the most primitive sample, high-Mg andesite from the southernmost volcanic center in the Andes (540S) has Sr and Nd isotopic compositions and K/Rb and Ba/La similar to MORB. The high La/Yb of this sample suggests formation by small degrees of partial melting of subducted MORB with garnet as a residue. Samples from centers farther north in the AVZ show a regionally regular northward increase in SiO2, K2O, Rb, Ba, Ba/La, and 87Sr/86Sr and decrease in MgO, Sr, K/Rb, Rb/Cs, and 143Nd/144Nd, suggesting increasingly greater degrees of fractional crystallization and associated intra-crustal contamination. (orig./SHOE)

  17. Source apportionment of PM{sub 10} and PM{sub 2.5} in a desert region in northern Chile

    Energy Technology Data Exchange (ETDEWEB)

    Jorquera, Héctor, E-mail: jorquera@ing.puc.cl; Barraza, Francisco

    2013-02-01

    Estimating contributions of anthropogenic sources to ambient particulate matter (PM) in desert regions is a challenging issue because wind erosion contributions are ubiquitous, significant and difficult to quantify by using source-oriented, dispersion models. A receptor modeling analysis has been applied to ambient PM{sub 10} and PM{sub 2.5} measured in an industrial zone ∼ 20 km SE of Antofagasta (23.63°S, 70.39°W), a midsize coastal city in northern Chile; the monitoring site is within a desert region that extends from northern Chile to southern Perú. Integrated 24-hour ambient samples of PM{sub 10} and PM{sub 2.5} were taken with Harvard Impactors; samples were analyzed by X Ray Fluorescence, ionic chromatography (NO{sub 3}{sup −} and SO{sub 4}{sup =}), atomic absorption (Na{sup +}, K{sup +}) and thermal optical transmission for elemental and organic carbon determination. Receptor modeling was carried out using Positive Matrix Factorization (US EPA Version 3.0); sources were identified by looking at specific tracers, tracer ratios, local winds and wind trajectories computed from NOAA's HYSPLIT model. For the PM{sub 2.5} fraction, six contributions were found — cement plant, 33.7 ± 1.3%; soil dust, 22.4 ± 1.6%; sulfates, 17.8 ± 1.7%; mineral stockpiles and brine plant, 12.4 ± 1.2%; Antofagasta, 8.5 ± 1.3% and copper smelter, 5.3 ± 0.8%. For the PM{sub 10} fraction five sources were identified — cement plant, 38.2 ± 1.5%; soil dust, 31.2 ± 2.3%; mineral stockpiles and brine plant, 12.7 ± 1.7%; copper smelter, 11.5 ± 1.6% and marine aerosol, 6.5 ± 2.4%. Therefore local sources contribute to ambient PM concentrations more than distant sources (Antofagasta, marine aerosol) do. Soil dust is enriched with deposition of marine aerosol and calcium, sulfates and heavy metals from surrounding industrial activities. The mean contribution of suspended soil dust to PM{sub 10} is 50 μg/m{sup 3} and the peak daily value is 104 μg/m{sup 3}. For the

  18. Restoration of degraded drylands in northern Chile: The need of local stakeholders' participation to prevent and combat desertification

    Science.gov (United States)

    Jorquera-Jaramillo, Carmen; Yáñez-Acevedo, Marcia; Gutiérrez, Julio R.; Cortés-Bugueño, José Luis; Pastén-Marambio, Víctor; Barraza-Cepeda, Claudia

    2015-04-01

    Desertification is one of the main factors determining poverty, long-term socio-economic problems, natural resources depletion and disturbances in rural communities living at the Coquimbo Region drylands (North-Central Chile). The Chilean State, along with private initiatives, have invested 473.6 Million dollars (1976 to 2008) to recover degraded areas through afforestation and soil management of 1,373,758 hectares. However, there is no information about the impact of the practices and changes experienced by the local stakeholders. Therefore, there is a need for a comprehensive evaluation considering both socioeconomic and biophysical aspects. To this end, a Protocol on Integrated Assessment (IAPro, PRACTICE project) was applied in two rural communities, involving communal afforested sites and their adjacent degraded drylands: El Sauce (ES, Limarí province) and Las Cañas (LC, Choapa province), Coquimbo Region. Participatory afforestation and soil conservation projects were implemented at both sites by the Chilean National Forestry Service (CONAF) in agreement with each local community (Jiménez y Tapia Agricultural Community at ES and Las Cañas de Choapa Peasant's Community at LC). The protocol involved 7 steps: (1) Stakeholder platform identification and engagement; (2) Baseline assessment and selection of site-specific indicators; (3) Integration and weighting of common and site-specific indicators; (4) Data collection; (5) Integrating and perspectives on a MCDA (Multi-Criteria Decision Analysis); (6) Collective Integrated assessment and knowledge sharing; (7) Dissemination. Interviews involved local and institutional stakeholders related to both sites' implementation, administration and/or local impacts. For the ES site, 5 actions were defined and assessed: No action (control); fences; mechanic and biological practices (soil stabilization, runoff control on slopes); runoff control in micro-basins, gullies and ravines; and footpath for educational and

  19. Investigating multiple fault rupture at the Salar del Carmen segment of the Atacama Fault System (northern Chile): Fault scarp morphology and knickpoint analysis

    Science.gov (United States)

    Ewiak, Oktawian; Victor, Pia; Oncken, Onno

    2015-02-01

    This study presents a new geomorphological approach to investigate the past activity and potential seismic hazard of upper crustal faults at the Salar del Carmen segment of the Atacama Fault System in the northern Chile forearc. Our contribution is based on the analysis of a large set of topographic profiles and allows extrapolating fault analysis from a few selected locations to distances of kilometers along strike of the fault. We detected subtle changes in the fault scarp geometry which may represent the number of paleoearthquakes experienced by the structure and extracted the cumulative and last incremental displacement along strike of the investigated scarps. We also tested the potential of knickpoints in channels crossing the fault scarps as markers for repeated fault rupture and proxies for seismic displacement. The number of paleoearthquakes derived from our analysis is 2-3, well in agreement with recent paleoseismological investigations, which suggest 2-3 earthquakes (Mw = 6.5-6.7) at the studied segments. Knickpoints record the number of events for about 55% of the analyzed profile pairs. Only few knickpoints represent the full seismic displacement, while most retain only a fraction of the displacement. The along-strike displacement distributions suggest fault growth from the center toward the tips and linkage of individual ruptures. Our approach also improves the estimation of paleomagnitudes in case of multiple fault rupture by allowing to quantify the last increment of displacement separately. Paleomagnitudes calculated from total segment length and the last increment of displacement (Mw = 6.5-7.1) are in agreement with paleoseismological results.

  20. Egg production and hatching success of Calanus chilensis and Acartia tonsa in the northern Chile upwelling zone (23°S), Humboldt Current System

    Science.gov (United States)

    Ruz, Paula M.; Hidalgo, Pamela; Yáñez, Sonia; Escribano, Rubén; Keister, Julie E.

    2015-08-01

    Oxygen Minimum Zones (OMZ's) are expanding and intensifying as result of climate change, affecting Eastern Boundary Upwelling Systems. Local effects of vertical movements of OMZ's that result from changes in upwelling intensity could reduce or expand the oxygenated surface layer that most zooplanktonic species inhabit in coastal areas. Using the copepods Calanus chilensis and Acartia tonsa as model organisms, an experimental test of the impact of different dissolved oxygen (DO) concentrations (between 0.5 and 5 ml L- 1) on egg production and hatching success was carried out and compared with field estimations of egg production, female and egg abundance in Mejillones Bay (23°S). Abundance of C. chilensis was highly variability and no consistent pattern in egg production and hatching success was found across DO levels, whereas A. tonsa egg production had maximum values between 2.6 and 4.7 ml O2 L- 1 and hatching success was positively correlated with DO (r = 0.75). In the field, temperature was the main factor controlling the dynamics of both species, while Chl-a and DO were also correlated with C. chilensis and A. tonsa, respectively. Principal Component Analysis showed that abundances of both copepods were controlled by temperature, stratification, OMZ depth, and Ekman transport, which together explained more than 70% of the total variance and were the main factors that modulated the populations of C. chilensis and A. tonsa in the upwelling zone of northern Chile (23°S). The differential responses of C. chilensis and A. tonsa to changes in DO concentrations associated with vertical movements of the OMZ suggest that C. chilensis may be better adapted to hypoxic conditions than A. tonsa, however both species are successful and persistent all year-round. We suggest that physiological responses of copepods could be used to evaluate population dynamics affected by the shoaling of OMZ's and the repercussions to trophic food webs of eastern boundary current systems.

  1. HPLC-UV-MS Profiles of Phenolic Compounds and Antioxidant Activity of Fruits from Three Citrus Species Consumed in Northern Chile

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    Anghel Brito

    2014-10-01

    Full Text Available Peels and edible pulp from three species of citrus including Citrus aurantifolia (varieties pica and sutil and Citrus x lemon var. Genova widely cultivated and consumed in Northern Chile (I and II region were analyzed for phenolic compounds and antioxidant activity for the first time. A high performance electrospray ionization mass spectrometry (HPLC-UV-ESI-MS method was developed for the rapid identification of phenolics in extracts from peels and juices of all species. Several flavonoids including one kaempferol-O-hexoside (peak 16 and one hesperidin derivative (peak 22 three quercetin derivatives (peaks 4, 19 and 36, five isorhamnetin derivatives (peaks 5, 23, 24, 26 and 29 four luteolin derivatives (peaks 14, 25, 27 and 40, seven apigenin derivatives (peaks 2, 3, 12, 20, 34, 35 and 39, seven diosmetin derivatives (peaks 7–9, 17, 21, 31 and 37, three chrysoeriol derivatives (peaks 10, 18 and 30, and four eryodictiol derivatives (peaks 6, 13, 15 and 38 were identified in negative and positive mode using full scan mass measurements and MSn fragmentations. Ascorbic acid content was higher in the pulps of the varieties Genova and Sutil (60.13 ± 1.28 and 56.53 ± 1.06 mg ascorbic acid per g dry weight, respectively while total phenolic content was higher in Pica peels followed by Sutil peels (34.59 ± 0.81 and 25.58 ± 1.02 mg/g GAE dry weight, respectively. The antioxidant capacity was also higher for Pica peels (10.34 ± 1.23 µg/mL in the DPPH assay and 120.63 ± 2.45 µM trolox equivalents/g dry weight in the FRAP assay. The antioxidant features together with the high polyphenolic contents can support at least in part, the usage of the peel extracts as nutraceutical supplements, especially to be used as anti-ageing products.

  2. The Bolivian and Maipo Oroclines: Two first scale structural features of the Central Andes

    Science.gov (United States)

    Arriagada, C. A.

    2013-05-01

    Two remarkable curvatures of the orogenic system of the Central Andes are the Bolivian and the Maipo Oroclines. While the former has been widely studied, the latter in central Chile, where few, geographically restricted, paleomagnetic studies have been carried out, knowledge about vertical-axis rotations is scarce. Here we show the results of the paleomagnetic studies carried out in the last years along the Central Andes within the Bolivian and Maipo Oroclines. Along-strike variations in horizontal shortening in the back- arc provided an efficient mechanism to explain the Bolivian Orocline and block rotations of the forearc region in northern Chile and southern Peru. As a first approximation, it appears reasonable that the arcuate shape of the Maipo Orocline could be accompanied by a significant pattern of rotations about a vertical axis in the forearc region and by a progressive decrease of crustal shortening and the resulting topography from north to south in the back-arc region. Furthermore, although the Maipo Orocline is located more than 1000 km south of the axial zone of the Central Andes, south of 30, clockwise rotations of up to 20 could have occurred during the evolution of the Bolivian Orocline. While the northern segment of the Maipo orocline corresponds with the ongoing subduction of the Pampean flat slab segment which proceeds nearly horizontally beneath the South American lithosphere, the southern segment coincides with the normal subduction segment developed to the south of 33S. The Maipo Orocline is thought to be result of collision of the Challenger Fracture Zone and Juan Fernández Ridge with the continent since 25 Ma. The southern flank of the Maipo Orocline can be traced along strike to around 38S. North of 33S, previous studies show no evidence for significant tectonic rotations. In contrary, south of 33S, both in the Coastal Cordillera and High Andes, clockwise block rotations have been observed and attributed to in situ block rotations in

  3. First remarks on the nesting biology of Hypodynerus andeus (Packard (Hymenoptera, Vespidae, Eumeninae in the Azapa valley, northern Chile Primeiras observações sobre a biologia da nidificação de Hypodynerus andeus (Packard (Hymenoptera, Vespidae, Eumeninae no vale de Azapa, norte do Chile

    Directory of Open Access Journals (Sweden)

    Felipe Méndez-Abarca

    2012-06-01

    Full Text Available First remarks on the nesting biology of Hypodynerus andeus (Packard (Hymenoptera, Vespidae, Eumeninae in the Azapa valley, northern Chile. Some aspects about the nesting biology of the potter wasp Hypodynerus andeus (Packard, 1869 are reported for the first time. Observations were carried out at the Azapa valley, coastal desert of northern Chile. A total of sixty nests were collected and examined, each composed by 1-14 cells, most of them found attached to concrete lamp posts. The only preys recorded in the cells were Geometridae (Lepidoptera caterpillars and the presence of the parasitoid Anthrax sp. (Diptera, Bombyliidae was also recorded. A number of arthropods belonging to different groups, mainly spiders, were found occupying empty nests.Primeiras observações sobre a biologia da nidificação de Hypodynerus andeus (Packard (Hymenoptera, Vespidae, Eumeninae no vale de Azapa, norte do Chile. Alguns aspectos da biologia da nidificação da vespa Hypodynerus andeus (Packard, 1869 são registrados pela primeira vez. As observações foram conduzidas no vale de Azapa, deserto litoral do norte do Chile. Sessenta ninhos foram coletados e examinados, cada um composto por 1-14 células. A maioria dos ninhos estava aderida a postes de concreto. As únicas presas registradas nas células foram larvas de Geometridae (Lepidoptera. Um parasitóide, Anthrax sp. (Diptera, Bombyliidae, foi também registrado. Vários artrópodes, principalmente aranhas, foram encontrados utilizando ninhos vazios.

  4. Magnetotelluric study of Parincota and Lascer volcanoes, central Andes

    International Nuclear Information System (INIS)

    Complete text of publication follows. This investigation considers two regions of interest, the first one includes the zone around Parinacota (6350 m, 18 deg09'S, 69 deg08'W), a subduction related stratovolcano situated in the limit of Bolivia and Chile, which had its biggest eruptive episodes around 8000 years ago. The second zone is more to the south, around Lascar volcano (5592 m, 23 deg22'S, 67 deg41'W), located on the eastern side of the Salar de Atacama basin in northern Chile, it has been one of the most active volcanoes of the central Andes in the last years. Between September and November 2007, magnetotelluric and audio magnetotelluric sites were built in the area close to Lascar and Parinacota volcanoes. AMT sites were installed in the proximities of the volcanoes, for a more shallow view, and the MT sites, which can reach longer periods and larger depths, were installed on a profile south of Lascar, which goes from the volcanic arc, crossing the Salar de Atacama basin, and as an outer ring in the Parinacota region. Remote reference and robust techniques were used in the data processing. Induction arrows, phase tensor ellipses and strike direction of the conductivity distribution have been calculated for the AMT sites, showing some 3-D behavior for the shallower depths, with induction vectors at the closest sites to the volcanoes pointing away from them, influenced by the topography. For the higher periods, the behavior is more 2-D in both regions, with a more stable strike direction which is coherent with the induction vectors and the largest semi axis of the phase tensor ellipses. All these parameters show a strong influence in the higher periods which seem to be due to a large conductive anomaly in the backarc, according with other studies in the zone, under the Bolivian altiplano. From a first analysis, deep large conductive bodies are not present in these zones around the volcanoes. Topographic corrections have been developed as well as sensitivity

  5. Meltwater palaeohydrology of the Baker River basin (Chile/Argentina) during Late Pleistocene deglaciation of the Northern Patagonia Icefield

    Science.gov (United States)

    Thorndycraft, Varyl; Bendle, Jacob; Benito, Gerardo; Sancho, Carlos; Palmer, Adrian; Rodríguez, Xavier

    2016-04-01

    The Late Pleistocene deglaciation of the Northern Patagonia Icefield (NPI) was characterised by rapid ice sheet thinning and retreat, and the development of large proglacial lake systems characterised by continental scale drainage reversals. In this region, research has focused primarily on the identification of former ice-limits (e.g. moraine ridges) for geochronological analyses, with little attention given to the meltwater palaeohydrology of major river valleys. The Baker River catchment drains the majority of the eastern ice shed of the NPI, with a basin area of 29,000 km2 that includes the large transboundary lakes of General Carrera/Buenos Aires and Cochrane/Puerreydón. The Baker River valley is aligned north to south, crossing the east-west valleys of the main NPI outflow glaciers, and thus represents an important aspect of regional Late Pleistocene palaeogeography. The Baker River valley therefore has the potential to refine regional models of deglaciation through better understanding of relationships between glacier dynamics, ice dammed lakes and meltwater pathways. Here we present geomorphological mapping from the Atlantic-Pacific drainage divide (over 150 km east of the Cordillera) to the lower Baker valley, in order to reconstruct Late Pleistocene palaeohydrology. We provide new mapping of palaeolake shoreline elevations and evidence for glacial lake outburst flood (GLOF) pathways that require a re-evaluation of the currently accepted palaeogeographic models. For example, the palaeohydrological evidence does not support existing models of a unified Buenos Aires/Puerreydón mega-lake at ca. 400m elevation. We propose a relative chronology of palaeohydrological events that help refine the published moraine chronology derived from cosmogenic nuclide exposure dating. Controls on Late Pleistocene meltwater palaeohydrology of the Baker catchment are discussed, including the interplay of glacial processes and regional tectonics, in particular, dynamic

  6. Exploring the Diversity and Antimicrobial Potential of Marine Actinobacteria from the Comau Fjord in Northern Patagonia, Chile.

    Science.gov (United States)

    Undabarrena, Agustina; Beltrametti, Fabrizio; Claverías, Fernanda P; González, Myriam; Moore, Edward R B; Seeger, Michael; Cámara, Beatriz

    2016-01-01

    Bioprospecting natural products in marine bacteria from fjord environments are attractive due to their unique geographical features. Although, Actinobacteria are well known for producing a myriad of bioactive compounds, investigations regarding fjord-derived marine Actinobacteria are scarce. In this study, the diversity and biotechnological potential of Actinobacteria isolated from marine sediments within the Comau fjord, in Northern Chilean Patagonia, were assessed by culture-based approaches. The 16S rRNA gene sequences revealed that members phylogenetically related to the Micrococcaceae, Dermabacteraceae, Brevibacteriaceae, Corynebacteriaceae, Microbacteriaceae, Dietziaceae, Nocardiaceae, and Streptomycetaceae families were present at the Comau fjord. A high diversity of cultivable Actinobacteria (10 genera) was retrieved by using only five different isolation media. Four isolates belonging to Arthrobacter, Brevibacterium, Corynebacterium and Kocuria genera showed 16S rRNA gene identity <98.7% suggesting that they are novel species. Physiological features such as salt tolerance, artificial sea water requirement, growth temperature, pigmentation and antimicrobial activity were evaluated. Arthrobacter, Brachybacterium, Curtobacterium, Rhodococcus, and Streptomyces isolates showed strong inhibition against both Gram-negative Pseudomonas aeruginosa, Escherichia coli and Salmonella enterica and Gram-positive Staphylococcus aureus, Listeria monocytogenes. Antimicrobial activities in Brachybacterium, Curtobacterium, and Rhodococcus have been scarcely reported, suggesting that non-mycelial strains are a suitable source of bioactive compounds. In addition, all strains bear at least one of the biosynthetic genes coding for NRPS (91%), PKS I (18%), and PKS II (73%). Our results indicate that the Comau fjord is a promising source of novel Actinobacteria with biotechnological potential for producing biologically active compounds. PMID:27486455

  7. On the uplift anomaly of the Arica Bend, Western Central Andes

    Science.gov (United States)

    Madella, Andrea; Delunel, Romain; Szidat, Sönke; Schlunegger, Fritz

    2015-04-01

    The architecture of the Western Andes is remarkably constant between southern Peru and northern Chile. An exception, however, is present near Arica at 18°S, where the Andes change their strike direction by ca. 50° and the Coastal Cordillera is absent over a lateral width of 50 km. Here, we propose a large-scale model to explain the Ma-long low-uplift rate of the Arica Bend in connection with interplate coupling and continental wedge-top basin evolution. We complement new geomorphic and sedimentological observations with structural, stratigraphic and seismic data compiled from the literature. We additionally present a new set of 14C ages to infer the Holocene uplift pattern of the region, which we support with stream profile analysis. Results show that the absence of a sediment barrier and the amphitheater-shaped topography at the Arica Bend has conditioned a relatively high sediment discharge to the corresponding trench segment since 2.7 Ma and possibly earlier. However, the 14C ages and the river profile analyses yield contradicting high coastal uplift rates for the past 10 ka. It appears that, at the large scale, higher sediment supply likely reduced the friction at the interplate boundary, keeping the uplift push at lower levels and the Coastal Cordillera submerged below Arica, thereby explaining the lower frequency of large subduction earthquakes in the area. Nonetheless, at a smaller scale, Quaternary sea-level fluctuations repeatedly shifted the water-load on the accretionary wedge, thereby inducing short-term elastic buckling, which has perturbed the trunk stream's profile.

  8. The Ordovician Quebrada Grande Formation, Cordón de Lila (Antofagasta Region, northern Chile): stratigraphicand paleogeographic significance La Formación QuebradaGrande, del Ordovícico, Cordón de Lila (Región de Antofagasta, norte de Chile): significado estratigráfico y paleogeográfico

    OpenAIRE

    Javier González; Hans Niemeyer; Juan L. Benedetto; Edsel D Brussa

    2007-01-01

    The Cordón de Lila is located immediately to the south of the Salar de Atacama, in northern Chile. The geology of the Cordón de Lila is characterized by extensive outcrops of Early Paleozoic volcanic and sedimentary rocks (Cordón de Lila Igneous and Sedimentary Complex; CISL) that form the 'Arco magmático occidental' (AMO) which is intruded by a multiple suite of Middle Ordovician to Lower Silurian granitoids. In this contribution we report the results of a sedimentological and paleontologica...

  9. Integrated provenance analysis of a convergent retroarc foreland system: U-Pb ages, heavy minerals, Nd isotopes, and sandstone compositions of the Middle Magdalena Valley basin, northern Andes, Colombia

    Science.gov (United States)

    Nie, Junsheng; Horton, Brian K.; Saylor, Joel E.; Mora, Andrés; Mange, Maria; Garzione, Carmala N.; Basu, Asish; Moreno, Christopher J.; Caballero, Victor; Parra, Mauricio

    2012-01-01

    Sediment provenance analysis remains a powerful method for testing hypotheses on the temporal and spatial evolution of uplifted source regions, but issues such as recycling, nonunique sources, and pre- and post-depositional modifications may complicate interpretation of results from individual provenance techniques. Convergent retroarc systems commonly contain sediment sources that are sufficiently diverse (continental magmatic arc, fold-thrust belt, and stable craton) to enable explicit provenance assessments. In this paper, we combine detrital zircon U-Pb geochronology, heavy mineral identification, Nd isotopic analyses, conventional sandstone petrography, and paleocurrent measurements to reconstruct the clastic provenance history of a long-lived sedimentary basin now exposed in an intermontane zone of the northern Andean hinterland of Colombia. The Middle Magdalena Valley basin, situated between the Central Cordillera and Eastern Cordillera, contains a 5-10 km-thick succession of Upper Cretaceous to Quaternary fill. The integrated techniques show a pronounced change in provenance during the Paleocene transition from the lower to upper Lisama Formation. We interpret this as a shift from an eastern cratonic source to a western Andean source composed of magmatic-arc rocks uplifted during initial shortening of the Central Cordillera. The appearance of detrital chloritoid and a shift to more negative ɛ Nd(t=0) values in middle Eocene strata of the middle La Paz Formation are attributed to shortening-related exhumation of a continental basement block (La Cira-Infantas paleohigh), now buried, along the axis of the Magdalena Valley. The diverse provenance proxies also show distinct changes during middle to late Eocene deposition of the Esmeraldas Formation that likely reflect initial rock uplift and exhumation of the fold-thrust belt defining the Eastern Cordillera. Upsection, detrital zircon U-Pb ages and heavy mineral assemblages for Oligocene and younger clastic

  10. Evolución tectónica, paleogeográfica y metalogénica durante el Cenozoico en los Andes de Chile norte y central e implicaciones para las regiones adyacentes de Bolivia y Argentina

    Directory of Open Access Journals (Sweden)

    Reynaldo Charrier

    2009-10-01

    Full Text Available La orogenia incaica dio origen a un importante relieve en el Eoceno Medio, el que se concentró en el ámbito del arco magmático precedente, la Cordillera Incaica. Este relieve positivo de orientación NNE se extendió desde el sur de Perú hasta la región central de Chile y separó dos dominios paleogeográficos que tuvieron evoluciones diferentes durante el resto del Cenozoico. El dominio occidental se caracterizó por el predominio de procesos de erosión y sedimentación. En el dominio oriental también existieron importantes episodios de erosión que originaron depósitos que se encuentran en la vertiente oriental de la cadena en la actualidad y presentan una cronología comparable con la de los depósitos del dominio occidental. Sin embargo, la evolución se caracterizó por presentar, a partir del Eoceno Tardío, diferencias al norte y sur de los ~27ºS. Al norte de esa latitud, en el ámbito del Altiplano-Puna, el arco magmático se mantuvo aproximadamente en la misma posición, coincidente con la del arco actual, y estuvo bordeado por una cuenca de antepaís de retroarco; mientras que, al sur de ~27ºS, se desarrollaron sucesivos arcos magmáticos con una marcada migración hacia el este. El arco magmático del Eoceno Tardío al Oligoceno Tardío - Mioceno Temprano se caracterizó por el desarrollo de una amplia cuenca extensional de intra-arco, la cuenca de Abanico. En esta cuenca se acumularon hasta 3.000 m de rocas volcánicas, volcaniclásticas y, subordinadamente, sedimentarias. A partir del límite oligoceno-mioceno, tuvo lugar un nuevo evento compresivo a lo largo de todo el orógeno que rejuveneció el núcleo de la Cordillera Incaica e invirtió la cuenca de Abanico permitiendo la generación de abundantes depósitos sintectónicos a ambos lados de los nuevos relieves. El inicio de este evento coincide con la orogenia pehuenche, los pulsos compresivos se mantuvieron hasta el Plioceno Temprano. En el Mioceno Temprano a Medio

  11. Geomorphological analysis, monitoring and modeling of large rock avalanches in northern Chile (Iquique area) for regional hazard assessment.

    Science.gov (United States)

    Yugsi Molina, F. X.; Hermanns, R. L.; Crosta, G. B.; Dehls, J.; Sosio, R.; Sepúlveda, S. A.

    2012-04-01

    mapped characterized by well defined lateral levees and clear internal morphological features (ridges and furrows, hummocks). Rock avalanche run out simulations have been carried out to back analyze the sites using DAN 3D and a 3 m pixel resolution digital elevation model (DEM) obtained from stereoscopic Geoeye-1 images to assess parameters that controlled propagation mechanism and impact area extent of the events. The older lobes were dated by radiocarbon methods. Results indicate ages higher than 40,000 yr BP for the northern site. The second site could only be dated relatively with an underlying terrace that resulted older than the age limit of radiocarbon dating (43.500 yr BP). All the deposits are positioned well above (40-70 m) the present sea level rise, and at the reported uplift rates for the area, they could be associated to events older than some hundreds of thousand years. A more complete record of the failure history of the sites will be obtained when results of cosmogenic nuclides (CN) and luminescence dating will become available later this year. Several other smaller rock avalanches have been mapped in the study area. Satellite-based radar interferometry (InSAR) was performed using ERS-1 and ERS-2 scenes from 1995-2000 as well as ENVISAT ASAR scenes from 2004-2010. Both datasets show only small deformation in the area. This deformation includes sliding of small surficial slope deposits and subsidence apparently due to local groundwater withdrawal. No deformation of bedrock along the escarpment edge is observed. Results show that only major rock avalanches could reach the main access roads to Iquique and currently no large slope segments show signs of large displacement rates. Moreover, there is no strong correlation between M > 8 earthquakes return periods and age of the dated deposits, which implies that large rock avalanches could have been triggered by other factors. Hence, from a hazard and risk perspective, it is unlikely that large rock avalanches

  12. Elastic Wavespeed Images of Northern Chile Subduction Zone from the Joint Inversion of Body and Surface Waves: Structure of the Andean Forearc and the Double Seismic Zone

    Science.gov (United States)

    Comte, D.; Carrizo, D.; Roecker, S. W.; Peyrat, S.; Arriaza, R.; Chi, R. K.; Baeza, S.

    2015-12-01

    Partly in anticipation of an imminent megathrust earthquake, a significant amount of seismic data has been collected over the past several years in northern Chile by local deployments of seismometers. In this study we generate elastic wavespeed images of the crust and upper mantle using a combination of body wave arrival times and surface wave dispersion curves. The body wave data set consists of 130000 P and 108000 S wave arrival times generated by 12000 earthquakes recorded locally over a period of 25 years by networks comprising about 360 stations. The surface wave data set consists of Rayleigh wave dispersion curves determined from ambient noise recorded by 60 broad band stations from three different networks over a period of three years. Transit time biases due to an uneven distribution of noise were estimated using a technique based on that of Yao and van der Hilst (2009) and found to be as high as 5% for some station pairs. We jointly invert the body and surface wave observations to both improve the overall resolution of the crustal images and reduce the trade-off between shallow and deep structures in the images of the subducted slab. Of particular interest in these images are three regions of anomalous Vp/Vs: (1) An extensive zone of low Vp/Vs (1.68) correlates with trench-parallel magmatic belts emplaced in the upper continental crust. In the region of the coast and continental slope, low Vp/Vs corresponds to batholithic structures in the Jurassic-Cretaceous magmatic arc. Between the central depression and Domeyko Cordillera, low Vp/Vs correlates with the distribution of magmatic arcs of Paleocene-Oligocene and Eocene-Oligocene age. Low Vp/Vs also correlates with the location of the Mejillones Peninsula. (2) A region of high Vp/Vs occurs in what is most likely the serpentinized wedge of the subduction zone. (3) An additional zone of low Vp/Vs is located in the middle of the double seismic zone at depths of 90-110 km. This region may exist all along the

  13. Caracterización y procedencia de obsidianas de sitios arqueológicos del Centro Oeste de Argentina y Centro de Chile con metodología no destructiva por fluorescencia de Rayos X (XRF Non-destructive x-ray fluorescence (XRF characterization and sourcing of obsidian from archaeological sites in Central West Argentina and Central Chile

    Directory of Open Access Journals (Sweden)

    Víctor Durán

    2012-11-01

    Full Text Available Se presentan los resultados de 101 análisis químicos por fluorescencia de Rayos X efectuados sobre artefactos de obsidiana provenientes de sitios arqueológicos del Centro Oeste Argentino y Chile Central. También se hace una caracterización química de seis fuentes y subfuentes de obsidiana ubicadas en ambientes cordilleranos y extracordilleranos del sur de Mendoza, Neuquén y Chile Central. Con esa información se discuten propuestas referidas a la movilidad y sistemas de intercambio de las sociedades humanas que ocuparon las dos vertientes de la cordillera de Los Andes durante el Holoceno medio y tardío. Los resultados obtenidos confirman que el método no destructivo por XRF es una herramienta válida para determinar el origen y dispersión de las obsidianas arqueológicas.The results of chemical analysis by X-ray Fluorescence (XRF performed on 101 obsidian artifacts from archaeological sites of Central western Argentina and Central Chile are presented. A chemical characterization of six obsidian sources and subsources located in both Andean and extra-Andean environments of Southern Mendoza, Northern Neuquén and Central Chile, is also performed. Based on this information, different proposals related to mobility patterns and exchange systems of human societies that occupied the two slopes of the Andes during the middle and late Holocene are discussed. The results confirm that non-destructive X-ray Fluorescence is a valid tool to determine the origin and dispersal of archaeological obsidian artifacts.

  14. Surface circulation patterns and the pathways of sea surface carbon dioxide (CO2 off northern Chile (~27.5° S between 30 and 10 kyr BP: global and/or local forcing?

    Directory of Open Access Journals (Sweden)

    R. Torres

    2010-03-01

    Full Text Available We present a reconstruction of past changes in partial pressure of CO2 (pCO2 from northern Chile (~27° S, between 10 and 30 kyr BP, based on carbon isotope composition of C37:2-alkenone. The high-pCO2 during the entire time series indicates that northern Chile upwelling system has been a permanent source of CO2 to the atmosphere. The multiproxy reconstruction suggests that the CO2 outgassing and sequestration pathways were modulated by local and global mechanisms. During global glacial conditions, an enhanced coastal upwelling forcing resulted in high-availability of deep water macronutrients and a CO2-supersaturated water column, which combined with high-inputs of iron from the continent, intensified the carbon sequestration pathway of the biological pump, through diatom biomass export. During the deglacial, a decrease in the upwelling forcing, an increment in water column stability and reduced continental inputs of iron are consistent with a larger role of calcifying organisms in the plankton assemblage in terms of carbon sequestration pathway through the carbonate system.

  15. Interseismic coupling and seismic potential along the Central Andes subduction zone

    Science.gov (United States)

    Chlieh, Mohamed; Perfettini, Hugo; Tavera, Hernando; Avouac, Jean-Philippe; Remy, Dominique; Nocquet, Jean-Mathieu; Rolandone, FréDéRique; Bondoux, Francis; Gabalda, Germinal; Bonvalot, Sylvain

    2011-12-01

    We use about two decades of geodetic measurements to characterize interseismic strain build up along the Central Andes subduction zone from Lima, Peru, to Antofagasta, Chile. These measurements are modeled assuming a 3-plate model (Nazca, Andean sliver and South America Craton) and spatially varying interseismic coupling (ISC) on the Nazca megathrust interface. We also determine slip models of the 1996 Mw = 7.7 Nazca, the 2001 Mw = 8.4 Arequipa, the 2007 Mw = 8.0 Pisco and the Mw = 7.7 Tocopilla earthquakes. We find that the data require a highly heterogeneous ISC pattern and that, overall, areas with large seismic slip coincide with areas which remain locked in the interseismic period (with high ISC). Offshore Lima where the ISC is high, a Mw˜8.6-8.8 earthquake occurred in 1746. This area ruptured again in a sequence of four Mw˜8.0 earthquakes in 1940, 1966, 1974 and 2007 but these events released only a small fraction of the elastic strain which has built up since 1746 so that enough elastic strain might be available there to generate a Mw > 8.5 earthquake. The region where the Nazca ridge subducts appears to be mostly creeping aseismically in the interseismic period (low ISC) and seems to act as a permanent barrier as no large earthquake ruptured through it in the last 500 years. In southern Peru, ISC is relatively high and the deficit of moment accumulated since the Mw˜8.8 earthquake of 1868 is equivalent to a magnitude Mw˜8.4 earthquake. Two asperities separated by a subtle aseismic creeping patch are revealed there. This aseismic patch may arrest some rupture as happened during the 2001 Arequipa earthquake, but the larger earthquakes of 1604 and 1868 were able to rupture through it. In northern Chile, ISC is very high and the rupture of the 2007 Tocopilla earthquake has released only 4% of the elastic strain that has accumulated since 1877. The deficit of moment which has accumulated there is equivalent to a magnitude Mw˜8.7 earthquake. This study thus

  16. Petrology, geochemistry and thermobarometry of the northern area of the Flamenco pluton, Coastal Range batholith, northern Chile. A thermal approach to the emplacement processes in the Jurassic andean batholiths

    Science.gov (United States)

    Rodríguez, Natalia; Díaz-Alvarado, Juan; Rodríguez, Carmen; Riveros, Karl; Fuentes, Paulina

    2016-04-01

    The Flamenco pluton is part of a N-S alignment of Late Triassic to Early Jurassic intrusive belt comprising the westernmost part of the Coastal Range batholith in northern Chile. The Jurassic-Cretaceous voluminous magmatism related to subduction in the western active continental margin of Gondwana is emplaced in the predominantly metasedimentary Paleozoic host-rocks of the Las Tórtolas formation, which in the northern area of the Flamenco pluton present an intense deformation, including the Chañaral mélange. Geochemically, the Flamenco pluton shows a wide compositional variability (SiO2 between 48wt % and 67wt %). Gabbros, Qtz-diorites and tonalites, mesocratic and leucocratic granodiorites are classified as calc-alkaline, calcic, magnesian and metaluminous magmatism. Flamenco granitoids define cotectic linear evolution trends, typical of magmatic fractionation processes. Geochemical trends are consistent with magmas evolved from undersaturated and low-pressure melts, even though the absence of transitional contacts between intrusive units precludes in-situ fractionation. Although some granodioritic samples show crossed geochemical trends that point to the compositional field of metasediments, and large euhedral prismatic pinnite-biotite crystals, typical Crd pseudomorph, are observed in contact magmatic facies, geochemical assimilation processes are short range, and the occurrence of host-rocks xenoliths is limited to a few meters from the pluton contact. A thermal approach to the emplacement process has been constrained through the thermobarometric results and a 2D thermo-numerical model of the contact aureole. Some Qtz-diorites and granodiorites located in the north area of the pluton exhibit granulitic textures as Hbl-Pl-Qtz triple junctions, poikiloblastic Kfs and Qtz recrystallization. The Hbl-Pl pairs have been used for the thermobarometric study of this metamorphic process, resulting granoblastic equilibrium temperatures between 770 and 790 °C, whereas

  17. Mujeres de los Andes

    OpenAIRE

    Arango, Luz Gabriela; Arizabaleta de García, María Teresa; Bejarano, Nilse; Borchart de Moreno, Christiana; Bucheli, Rocío Vaca; Cervantes, Elvira Llanos; Cisneros, Tatiana; Defossez, Anne-Claire; Fassin, Didier; Giraldo, Fernando Urrea; Li, Dina; Malaver, José; Montúfar, Verónica; Moscoso, Martha; Ortega, Diego Zapata

    2016-01-01

    El Seminario "Mujeres De Los Andes: Condiciones De Vida Y Salud" tuvo lugar en la ciudad de Quito, del 6 al 10 de junio de 1991. Reunió investigadores de distintas disciplinas académicas y actores de variados campos, de cuatro países del área andina-Bolivia, Colombia, Ecuador y Perú-, en los cuales está presente el Instituto Francés de Estudios Andinos, principal instigador del evento. Este libro, que reúne la mayor parte de las ponencias en él presentadas, se inscribe en la línea de las corr...

  18. RESISTENCIA DE Phytophthora infestans (Montagne) de Bary A METALAXIL, EN CULTIVO DE PAPAS EN EL NORTE DE CHILE Resistance of Phytophthora infestans (Montagne) de Bary to metalaxyl in potato crops in Northern Chile

    OpenAIRE

    Fernando Riveros B.; Rodrigo Sotomayor; Viviana Rivera; Gary Secor; Boris Espinoza

    2003-01-01

    Con el objeto de determinar la sensibilidad a metalaxil de dos poblaciones de Phytophthora infestans (Montagne) de Bary, en cultivos de papa (Solanum tuberosum L.) en diferentes localidades de la IV y V Región de Chile, se estudiaron mediante ensayos in vitro e in vivo 254 aislamientos, los cuales inicialmente fueron calificado como sensibles o resistentes de acuerdo a su crecimiento sobre agar centeno B y 10 mg L-1 de metalaxil. Su concentración efectiva media (CE 50), fue estimada mediante ...

  19. El género Cymatoceras (Nautilida) en el Cretácico Inferior de la Cuenca de Atacama, norte de Chile The genus Cymatoceras (Nautilida) in the Lower Cretaceous of the Atacama Basin, northern Chile

    OpenAIRE

    Marcela Cichowolski; Francisco A. Mourgues; Ernesto Pérez d'A

    2004-01-01

    Se describen restos fragmentarios de nautílidos del género Cymatoceras Hyatt, provenientes de estratos barremianos de la Cuenca de Atacama, norte de Chile. Los especímenes corresponden a dos taxones: Cymatoceras sp. del Barremiano tardío alto, cuya preservación es deficiente, aunque su tipo de ornamentación, con costillas gruesas y un seno ventral muy marcado, es sólo conocida, hasta el momento, en este taxón y Cymatoceras cf. perstriatum (Steuer), del Barremiano tardío. El material chileno e...

  20. Dinámica trófica del jurel (Trachurus symmetricus murphyi) en el norte de Chile Trophic dynamic of jack mackerel (Trachurus symmetricus murphyi) in northern Chile

    OpenAIRE

    Marianela Medina; Hugo Arancibia

    2002-01-01

    Se determinó la dinámica trófica del jurel Trachurus symmetricus murphyi capturado frente a las costas de la zona norte de Chile, desde la primavera de 1993 hasta el invierno de 1994. Se consideró la importancia relativa de las presas, la identificación de unidades ontogenéticas tróficas y la selectividad de presas por tamaño. Las muestras se obtuvieron de las líneas de descarga de las plantas pesqueras en los puertos de Arica, Iquique, Tocopilla y Mejillones. En el laboratorio se identificar...

  1. La fauna de caprélidos (Crustacea: Amphipoda: Caprellidea de la costa de Coquimbo, centro-norte de Chile, con una clave taxonómica para la identificación de las especies The caprellid fauna (Crustacea: Amphipoda: Caprellidea from the coast of Coquimbo, Northern-central Chile, with a taxonomic key for species identification

    Directory of Open Access Journals (Sweden)

    JOSÉ M. GUERRA-GARCÍA

    2001-12-01

    difficult due to the high degree of intra-specific morphological variability and the fact that literature and specimens from Museums are not easily located. The objective of the present study was to provide the taxonomical tools to identify the most common caprellid species from northern-central Chile. Several habitats were examined (buoys, boulders, algal/seagrass beds and six caprellid species were found: Caprellina longicollis (Nicolet, 1849, Caprella equilibra Say, 1818, C. scaura Templeton, 1836, C. verrucosa Boeck, 1871; Deutella venenosa Mayer, 1890 and Paracaprella pusilla Mayer, 1890. Caprella scaura, C. verrucosa and D. venenosa were most abundant among algae, hydrozoans and bryozoans growing on buoys. Caprella equilibra, also present on buoys, was most abundant underneath boulders in exposed rocky intertidal zones, where additionally D. venenosa and P. pusilla were found. Caprella scaura was dominant in plant beds above sandy subtidal bottom, especially among the alga Gracilaria chilensis and the seagrass Heterozostera tasmanica, where it occurred together with Caprellina longicollis. Paracaprella pusilla represents a new citation for the pacific coasts of S-America, being a new record for Chile. The species D. venenosa, which was recorded for the first time since the original description by Mayer in the year 1890, is considered an endemic species from the central coast of Chile

  2. Cultivation of cystocarpic, tetrasporic and vegetative fronds of Chondracanthus chamissoi (Rhodophyta, Gigartinales on ropes at two localities in northern Chile Cultivo de frondas cistocárpicas, tetraspóricas y vegetativas de Chondracanthus chamissoi (Rhodophyta, Gigartinales en dos localidades del norte de Chile

    Directory of Open Access Journals (Sweden)

    Cristian Bulboa

    2006-05-01

    Full Text Available Chondracanthus chamissoi is a red algae that is highly valuated as a delicacy in Japan bringing a good price. However, this market demands a high quality product that can not be easily harvested from natural populations. Here we present results showing that it is technically feasible to cultivate this species on ropes in the sea. We tested two sites in northern Chile comparing the performance of reproductive and vegetative specimens. The best results were obtained at Calderilla bay using vegetative frondsChondracanthus chamissoi es una macroalga altamente apreciada como alimento natural en países asiáticos, alcanzando buenos precios internacionales. Sin embargo, este mercado demanda un producto de alta calidad, el cual difícilmente puede ser obtenido a partir de poblaciones naturales. En este trabajo, se muestra que es técnicamente posible cultivar esta especie a partir de talos dispuestos en cuerdas. Se realizaron cultivos en dos bahías del norte de Chile y se compararon los desarrollos de talos reproductivos y vegetativos. Los mejores resultados se obtuvieron en bahía Calderilla con talos vegetativos

  3. An InSAR-based survey of volcanic deformation in the central Andes

    OpenAIRE

    M. E. Pritchard; Simons, M.

    2004-01-01

    We extend an earlier interferometric synthetic aperture radar (InSAR) survey covering about 900 remote volcanos of the central Andes (14°–27°S) between the years 1992 and 2002. Our survey reveals broad (10s of km), roughly axisymmetric deformation at 4 volcanic centers: two stratovolcanoes are inflating (Uturuncu, Bolivia, and Hualca Hualca, Peru); another source of inflation on the border between Chile and Argentina is not obviously associated with a volcanic edifice (here called Lazufre); a...

  4. Hippidion saldiasi Roth, 1899 (Mammalia, Perissodactyla en el Pleistoceno tardío de Calama, norte de Chile Late Pleistocene Hippidion saldiasi Roth, 1899 (Mammalia, Perissodactyla from Calama, northern Chile

    Directory of Open Access Journals (Sweden)

    MARÍA TERESA ALBERDI

    2007-06-01

    Full Text Available Se describen restos del género Hippidion procedentes de la zona del desierto de Atacama (Calama, Segunda Región de Chile. El conjunto analizado corresponde a un esqueleto bastante completo proveniente del yacimiento Betecsa 1, así como escasas unidades del yacimiento Kamac Mayu. En ambos sitios se identifica H. saldiasi. A partir de dos dataciones radiométricas por AMS del ejemplar estudiado, los restos se sitúan estratigráficamente en el Pleistoceno Superior (21.070 ± 100 AP y 21.380 ± 100 14C AP. Se infieren datos ambientales y de dieta a partir de análisis de isótopos estables en los restos de Hippidion saldiasi del sitio Betecsa 1 cuyo valor de δ13C en hueso fue de -15,45 y el valor en esmalte de dientes fue de -16,68, sugiriendo una alimentación con pastos C3. El cráneo recuperado es el primero conocido de esta especieThis paper describes the Hippidion bones recovered from the Atacama Desert (Calama, Second Region of Chile. The analyzed assemblage corresponds to a nearly complete skeleton from Betecsa 1 site and more poorly preserved remains from Kamac Mayu site. In both H. saldiasi is identified. Two 14C radiometric determinations indicate late Pleistocene age for these remains (21,070 ± 100 BP and 21,380 ± 100 BP. Environmental and diet inferences from stable isotope analysis are also presented. The δ13C value from Betecsa 1 horses (-15.45 from bone sample and -16.68 from enamel sample suggest a dietary adaptation exclusively C3 feeders. This is the first skull and associated skeleton recovered of this species

  5. Movilidad y uso del espacio entre cazadoresrecolectores tardíos en espacios cordilleranos del Norte Semiárido de Chile MOBILITY AND SPACE USE AMONG LATE HUNTER-GATHERERS IN CORDILLERAN SEMIARID NORTHERN CHILE

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    César A. Méndez

    2009-12-01

    Full Text Available Se discute la organización espacial de los cazadores recolectores en el valle cordillerano de Pama en el Norte Semiárido de Chile, durante el lapso calendario entre 1700 a 900 años atrás. Se observa un registro que integra múltiples localidades que incluyeron campamentos a cielo abierto y bajo reparos rocosos y sectores de expresión de arte rupestre. Abordamos el tema usando escalas espaciales explícitas e integramos información crono-estratigráfica, tecnológica y contextual. Comparamos nuestra información con conjuntos contemporáneos de áreas aledañas a fin de caracterizar las particularidades en el uso del espacio. Finalmente, proponemos que los grupos en sectores cordilleranos como éste mantuvieron patrones tradicionales de uso del espacio, bajo un modo de vida cazador recolector aún con la incorporación de tecnología cerámica durante momentos tardíos en la prehistoria regional.The spatial organization of hunter-gatherers in the mountainous Pama river basin of the Semiarid North of Chile, 1700 to 900 calendar years BP, is discussed. The observed record consists of several localities that include open-air and rock-shelter camps and areas with rock art. The subject was approached through the use of explicit spatial scales and by integrating chrono-stratigraphic, technological and contextual information. The information gathered was compared to contemporary data sets from nearby areas in order to characterize the particularities of space use. It is proposed that groups in mountainous areas such as these maintained traditional space use patterns within a hunter-gatherer lifestyle even with the incorporation of ceramic technology until late in the region's prehistory.

  6. Streamflow responses in Chile to megathrust earthquakes in the 20th and 21st centuries

    Science.gov (United States)

    Mohr, Christian; Manga, Michael; Wang, Chi-yuen; Korup, Oliver

    2016-04-01

    Both coseismic static stress and dynamic stresses associated with seismic waves may cause responses in hydrological systems. Such responses include changes in the water level, hydrochemistry and streamflow discharge. Earthquake effects on hydrological systems provide a means to study the interaction between stress changes and regional hydrology, which is otherwise rarely possible. Chile is a country of frequent and large earthquakes and thus provides abundant opportunities to study such interactions and processes. We analyze streamflow responses in Chile to several megathrust earthquakes, including the 1943 Mw 8.1 Coquimbo, 1950 Mw 8.2 Antofagasta, 1960 Mw 9.5 Valdivia, 1985 Mw 8.0 Valparaiso, 1995 Mw 8.0 Antofagasta, 2010 Mw 8.8 Maule, and the 2014 Mw 8.2 Iquique earthquakes. We use data from 716 stream gauges distributed from the Altiplano in the North to Tierra del Fuego in the South. This network covers the Andes mountain ranges, the central valley, the Coastal Mountain ranges and (mainly in the more southern parts) the Coastal flats. We combine empirical magnitude-distance relationships, machine learning tools, and process-based modeling to characterize responses. We first assess the streamflow anomalies and relate these to topographical, hydro-climatic, geological and earthquake-related (volumetric and dynamic strain) factors using various classifiers. We then apply 1D-groundwater flow modeling to selected catchments in order to test competing hypotheses for the origin of streamflow changes. We show that the co-seismic responses of streamflow mostly involved increasing discharges. We conclude that enhanced vertical permeability can explain most streamflow responses at the regional scale. The total excess water released by a single earthquake, i.e. the Maule earthquake, yielded up to 1 km3. Against the background of megathrust earthquakes frequently hitting Chile, the amount of water released by earthquakes is substantial, particularly for the arid northern

  7. Remote sensing and climate data as a key for understanding fasciolosis transmission in the Andes: review and update of an ongoing interdisciplinary project

    Directory of Open Access Journals (Sweden)

    Màrius V. Fuentes

    2006-11-01

    Full Text Available Fasciolosis caused by Fasciola hepatica in various South American countries located on the slopes of the Andes has been recognized as an important public health problem. However, the importance of this zoonotic hepatic parasite was neglected until the last decade. Countries such as Peru and Bolivia are considered to be hyperendemic areas for human and animal fasciolosis, and other countries such as Chile, Ecuador, Colombia and Venezuela are also affected. At the beginning of the 1990s a multidisciplinary project was launched with the aim to shed light on the problems related to this parasitic disease in the Northern Bolivian Altiplano. A few years later, a geographic information system (GIS was incorporated into this multidisciplinary project analysing the epidemiology of human and animal fasciolosis in this South American Andean region. Various GIS projects were developed in some Andean regions using climatic data, climatic forecast indices and remote sensing data. Step by step, all these GIS projects concerning the forecast of the fasciolosis transmission risk in the Andean mountain range were revised and in some cases updated taking into account new data. The first of these projects was developed on a regional scale for the central Chilean regions and the proposed model was validated on a local scale in the Northern Bolivian Altiplano. This validated mixed model, based on both fasciolosis climatic forecast indices and normalized difference vegetation index values from Advanced Very High Resolution Radiometer satellite sensor, was extrapolated to other human and/or animal endemic areas of Peru and Ecuador. The resulting fasciolosis risk maps make it possible to show the known human endemic areas of, mainly, the Peruvian Altiplano, Cajamarca and Mantaro Peruvian valleys, and some valleys of the Ecuadorian Cotopaxi province. Nevertheless, more climate and remote sensing data, as well as more accurate epidemiological reports, have to be

  8. Simulation model of the scallop (Argopecten purpuratus farming in northern Chile: some applications in the decision making process Modelo de simulación para el cultivo del ostión (Argopecten purpuratus en el norte de Chile: aplicaciones para la toma de decisiones

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    Renato Molina

    2012-09-01

    Full Text Available Aquaculture farming is a complex system integrating several disciplines, including biology, engineering and economics, all which need to be correctly intertwined to have a profitable and environmentally sustainable activity. During the past recent years, scallop (Argopectenpurpuratus farmers in northern Chile have come to comprehend the hard way that aquaculture producers operate in a complex and dynamic environment where natural and economic factors are in constant change. Thus, to keep a profitable and competitive business in today's world, aquaculture farm managers are in need of relatively easy to use tools for efficient and timely decision making. Harvest size and time, mortality and growth rates, stocking rates, costs and market prices are important variables and parameters to monitor, where decisions with respect to their levels or values have to be made. In this context, non-linear and dynamic quantitative bioeconomic models should become valuable tools, for periodic decision making in the aquaculture business. This paper shows how to emulate Chilean scallop farming using a simulation model that mimics some of the industry's features. The model presented here focuses on a scallop aquaculture center that uses the common technology approach of pearl net and lanterns of the northern region of Chile, and analyses the farming strategies based on harvesting size. Also, these strategies were subject to variations in the parameters in order to identify patterns and asses the sensibility of the model to input values.La acuicultura es un sistema complejo que integra varias disciplinas, incluyendo la biología, ingeniería y economía, las cuales deben ser correctamente entrelazadas para lograr una actividad rentable y ambientalmente sostenible. Durante los últimos anos, los cultivadores del ostión del norte (Argopecten purpuratus en Chile han comprendido de la peor manera, que las actividades de acuicultura operan en un entorno complejo y din

  9. 77 FR 65574 - Lake Andes National Wildlife Refuge Complex, Lake Andes, SD; Draft Comprehensive Conservation...

    Science.gov (United States)

    2012-10-29

    ... Complex. We started this process through a notice in the Federal Register (72 FR 27328; May, 15, 2007... Fish and Wildlife Service Lake Andes National Wildlife Refuge Complex, Lake Andes, SD; Draft... assessment (EA) for the Lake Andes National Wildlife Refuge Complex (Complex), which includes Lake Andes...

  10. RESISTENCIA DE Phytophthora infestans (Montagne de Bary A METALAXIL, EN CULTIVO DE PAPAS EN EL NORTE DE CHILE Resistance of Phytophthora infestans (Montagne de Bary to metalaxyl in potato crops in Northern Chile

    Directory of Open Access Journals (Sweden)

    Fernando Riveros B.

    2003-04-01

    Full Text Available Con el objeto de determinar la sensibilidad a metalaxil de dos poblaciones de Phytophthora infestans (Montagne de Bary, en cultivos de papa (Solanum tuberosum L. en diferentes localidades de la IV y V Región de Chile, se estudiaron mediante ensayos in vitro e in vivo 254 aislamientos, los cuales inicialmente fueron calificado como sensibles o resistentes de acuerdo a su crecimiento sobre agar centeno B y 10 mg L-1 de metalaxil. Su concentración efectiva media (CE 50, fue estimada mediante un modelo de regresión lineal entre el logaritmo de seis concentraciones de metalaxil (0, 150, 250, 350, 450 y 550 mg L-1 y porcentaje de inhibición transformado a unidades Probit. Los resultados de ambas temporadas demostraron que la totalidad de los aislamientos de P. infestans fueron resistentes a metalaxil. Aislamientos colectados en la IV Región durante 1999 presentaron variaciones de CE 50 entre 243 y 687 mg L-1 de metalaxil, 9,6% de ellos prresentó CE 50 inferior a 300 mg L-1 de metalaxil. Aislamientos colectados en la V Región variaron su CE 50 entre 233 y 633 mg L-1 de metalaxil y solamente 10,1% de ellos presentó CE 50 inferior a 300 mg L-1 de metalaxil. La totalidad de los aislamientos colectados en la temporada 2000 fueron resistentes al fungicida, 89,6 y 78,1% de los colectados en la IV y V Región respectivamente, presentaron CE 50 superiores a 350 mg L-1 de metalaxil. Los resultados del bioensayo fueron consistentes con el trabajo in vitro.The objective of this study was to determine the sensitivity to metalaxyl of two populations of Phytophthora infestans (Montagne de Bary, affecting potato (Solanum tuberosum L. crops in the IV and V Regions of Chile. A total of 254 isolates were studied in vitro and in vivo which were initially classified as sensitive or resistant according to their growth on Rye B media amended with 10 mg L-1 metalaxyl. CE 50 (effective concentration values were estimated for each isolate from a regression curve of

  11. Lithospheric scale model of Merida Andes, Venezuela (GIAME Project)

    Science.gov (United States)

    Schmitz, M.; Orihuela, N. D.; Klarica, S.; Gil, E.; Levander, A.; Audemard, F. A.; Mazuera, F.; Avila, J.

    2013-05-01

    Merida Andes (MA) is one of the most important orogenic belt in Venezuela and represents the northern culmination of South America Andes. During the last 60 years, several models have been proposed to explain the shallow and deep structure, using different geological, geophysical, seismological, geochemical and petrologic concepts; nevertheless, most of them have applied local observation windows, and do not represent the major structure of MA. Therefore, a multidisciplinary research group, coordinated by FUNVISIS, in close cooperation with UCV, ULA and PDVSA, is proposed in order to get the outlined goals in the project entitled GIAME ("Geociencia Integral de los Andes de MErida") was established, which aims to generate a lithospheric scale model and the development of a temporal dynamic model for the MA. As a base for lithospheric investigations of the Merida Andes, we are proposing three wide angle seismic profiles across the orogen on three representative sites, in order to determine the inner structure and its relation with the orogen's gravimetric root. To the date, there are no seismic studies at lithospheric scale which cross MA. The wide angle seismic will be complemented with the re-processing and re-interpretation of existing reflection seismic data, which will allow to establish a relationship between MA and its associated flexural basins (Maracaibo and Barinas-Apure basins). Depending on the results of the VENCORP Project (VENezuelan COntinental Reflection Profiling), which might show some reliable results about crustal features and Moho reflectors along three long seismic profiles at Caribbean Moutain system, a reflection seismic profile across the central portion of MA is proposed. Additional tasks, consisting in MA quaternary deformation studies, using research methods like neotectonics and paleoseismology, georadar, numerical modeling, cinematic GPS, SAR interferometry, thermocronology, detailed studies on regional geology, flexural modeling

  12. Fold and thrust belt structures and strike-slip faulting at the SE margin of the Salar de Atacama basin, Chilean Andes

    Science.gov (United States)

    Kuhn, Dirk

    2002-07-01

    A tectonic reinterpretation is reported for the southeastern margin of the Salar de Atacama basin of northern Chile. Detailed structural mapping revealed the presence of an east vergent thin-skinned fold and thrust belt affecting Oligocene-Miocene Paciencia Group rocks and the overlying Plio-Pleistocene volcanic rocks. Along-strike segmentation of the main fold implies local foreland influence on footwall ramp geometry leading to local thrust sheet rotation. To the east the adjacent western slope of the Western Cordillera displays two different structural domains, probably controlled by preexisting basement structures. The southern domain comprises two N-S oriented sigmoidal belts of linear arranged pressure ridges, indicating left-lateral transpression. In contrast, the northern domain is characterized by east vergent fold and thrust belt structures and reactivated NW-SE striking sinistral strike-slip faults, governing clockwise block rotations. An indenter-driven deformation model is proposed to explain sinistral transpression and clockwise block rotations around vertical axes. This variant of a small-block rotation mechanism is discussed in the context of oroclinal bending of the central Andes, emphasizing the significance of ancient structures in controlling rotations.

  13. Across the southern Andes on fin: glacial refugia, drainage reversals and a secondary contact zone revealed by the phylogeographical signal of Galaxias platei in Patagonia.

    Science.gov (United States)

    Zemlak, Tyler S; Habit, Evelyn M; Walde, Sandra J; Battini, Miguel A; Adams, Emily D M; Ruzzante, Daniel E

    2008-12-01

    We employed DNA sequence variation at two mitochondrial (control region, COI) regions from 212 individuals of Galaxias platei (Pisces, Galaxiidae) collected throughout Patagonia (25 lakes/rivers) to examine how Andean orogeny and the climatic cycles throughout the Quaternary affected the genetic diversity and phylogeography of this species. Phylogenetic analyses revealed four deep genealogical lineages which likely represent the initial division of G. platei into eastern and western lineages by Andean uplift, followed by further subdivision of each lineage into separate glacial refugia by repeated Pleistocene glacial cycles. West of the Andes, refugia were likely restricted to the northern region of Patagonia with small relicts in the south, whereas eastern refugia appear to have been much larger and widespread, consisting of separate northern and southern regions that collectively spanned most of Argentinean Patagonia. The retreat of glacial ice following the last glacial maximum allowed re-colonization of central Chile from nonlocal refugia from the north and east, representing a region of secondary contact between all four glacial lineages. Northwestern glacial relicts likely followed pro-glacial lakes into central Chilean Patagonia, whereas catastrophic changes in drainage direction (Atlantic --> Pacific) for several eastern palaeolakes were the likely avenues for invasions from the east. These mechanisms, combined with evidence for recent, rapid and widespread population growth could explain the extensive contemporary distribution of G. platei throughout Patagonia. PMID:19017262

  14. Peces mesopelágicos frente a la costa norte de Chile (18°25'-21°47'S Mesopelagic fishes off northern Chile (18°25'-21°47'S

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    Walter Sielfeld K

    1995-01-01

    Full Text Available Se estudian los peces mesopelágicos capturados en la capa profunda de dispersión sónica (DSL, en cinco transectos ubicados entre los 18°25' y 21°47'S frente a las costas de la I Región de Chile. Los transectos se extendieron desde las 10 a las 100 millas de la costa y las capturas se realizaron mediante una red de ti po IKMT de 9,16 m² de boca, en septiembre de 1988. Conjuntamente se registró la DSL mediante un equipo SIMRAD (32 KHz de frecuencia y las condiciones de temperatura y salinidad de cada: estación. En el área y período de estudio se detectaron 39 especies y 21 familias. En términos de biomasa la familia más importante fue Myctophidae (22%, mientras que en número de individuos destacó Gonostomatidae (67%. El 62% de la ictiocenosis correspondió a especies de aguas temperadas (tropicales y/o subtropicales y un 7,7% a especies de aguas frías (antárticas y/o subantárticas, sin que se pierda el carácter transicional de la comunidad. El análisis de diversidad de Shannon- Wiener y de similitud de Winer mostró la existencia de 4 grupos discretos de estaciones, determinados por condiciones oceanográficas y masas de agua particulares. La DSL mostró un descenso hasta los 250 m de profundidad durante el día y la separación de una capa que asciende hasta la superficie durante la nocheMesopelagic fishes captured in the deep scattering layer (DSL off the I Region of Chile, in 5 transects between 18°25' and 21°47'S, from 10 to 100 miles offshore, were studied. A 9.16 m² mouth IKMT net was used. The DSL was registered with a SIMRAD ecosounder at frecuencies of 32 Khz and jointly the oceanographic conditions at each station were recorded. In 23 sampling stations 20 families and 39 species of fishes were detected. Most abundant families were Myctophidae and Gonostomatidae, the former with 22% of total fish biomass and the latter 67% of total captured specimens. 62% of the identified species were temperate water elements

  15. Methane fluxes from a wet puna ecosystem in the Peruvian Andes

    Science.gov (United States)

    Jones, Sam; Diem, Torsten; Priscila Huaraca Quispe, Lidia; Quispe Ccahuana, Adan Julian; Meir, Patrick; Arn Teh, Yit

    2014-05-01

    Discrepancies exist between top-down and bottom-up estimates of the tropical South American atmospheric methane budget. This suggests that current source-sink inventories fail to adequately characterise the landscapes of the region. This may be particularly true of Andean environments where very few field observations have been made. The high tropical Andes, between tree and permanent snow-lines, is home to diverse grass, shrub and giant rosette dominated ecosystems known variously from Venezuela to northern Chile and Argentina as paramo, jalca and puna. In humid regions these are characterised by wet, organic-rich mineral soils, peat-forming wetlands and shallow lakes. Such conditions are likely to promote methane production and potentially represent a regionally significant source to the atmosphere that should be considered. We report on methane fluxes from a bunch-grass dominated puna habitat at 3500 m above sea level in south-eastern Peru. Mean annual temperature and precipitation are 11 °C and 2500 mm, respectively. Temperature is aseasonal but experiences considerable diurnal variations with overnight frosting common-place. In contrast, rainfall is intensely episodic and has a pronounced wet season between September and March. Sampling encompassed a range of topographic features, such as grassland on freely draining, gently inclined or steep slopes and depressions containing bogs, over a 3 ha ridge to basin transition. Monthly sampling was carried out between January 2011 and June 2013 to investigate seasonal variability in methane fluxes. Intensive sampling campaigns were conducted to investigate spatial and short-term variations on a daily basis in two nine-day campaigns during wet and dry season. The site was a net source of methane to the atmosphere during the period of study. Methane fluxes were dominated by emissions from bogs, whereas, freely draining grassland exhibited weak source or marginal sink activity. Temporal variations were most notable at

  16. Preliminary Evaluation of 29 Olive (Olea europaea L. Cultivars for Production and Alternate Bearing, in the Huasco Valley, Northern Chile Evaluación Preliminar de la Produción y Añerismo en 29 Variedades de Olivo (Olea europaea L. en el Valle del Huasco, Norte de Chile

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    Francisco Tapia C

    2009-09-01

    Full Text Available There is increasing interest in the development of intensively managed olive orchards (Olea europaea L. in northern Chile. The selection of specific varieties that perform well on a particular site is considered crucial to maximizing productivity. The present study was undertaken to evaluate the productive performance of 29 varieties of olive in the Huasco Valley (28°34' S, 70°47' W, Northern Chile.The traits evaluated were: mean olive production per tree considering a longitudinal (PML analysis over a period of five years, 2003 to 2007, total olive production in the same period (PA03-07 and alternate bearing index (ABI. The effect of variety was highly significant (p En el norte de Chile existe un creciente interés en el desarrollo de huertos de olivo (Olea europaea L. manejados intensivamente. La selección de variedades específicas que han respondido bien en un sitio en particular es considerada clave para la maximización de la productividad. El presente estudio fue realizado para evaluar el desempeño de algunas características agronómicas en 29 variedades de olivo, en el Valle del Huasco (28°34' S, 70°47' O, norte de Chile. Las características analizadas correspondieron a producción de frutos promedio por árbol (PML en un análisis longitudinal durante un período de 5 años, 2003 a 2007, producción acumulada del mismo período (PA03-07 y el índice de alternancia de producción (ABI. El efecto debido a la variedad fue altamente significativo (p < 0,01 para las tres características. El ABI fue moderado (0,52, con una PML de 37,37 kg árbol-1 y PA03-07 de 186 kg árbol-1. Correlaciones de Spearman entre los ranking de cada característica fueron positivas y significativamente diferentes de cero (p < 0,05. ‘Leccino’ tuvo la mejor respuesta considerando únicamente la producción de frutos. ‘Arbequina’, ‘Picholine’, ‘Manzanilla Racimo’, ‘Picual’, ‘Manzanilla de Sevilla’, ‘Frantoio’ y

  17. Un modelo trófico preliminar del ecosistema pelágico del norte de Chile (18°20’S-24°00’S A preliminary trophic model of the pelagic ecosystem in northern Chile (18°20’S-24°00’S

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    Marianela Medina

    2007-05-01

    Full Text Available Se construye un modelo ecotrófico con balance de masa para cuantificar los flujos de energía/materia e interacciones tróficas en la trama trófica del ecosistema pelágico del norte de Chile, en el año 1989. El modelo incluye 13 grupos funcionales, siendo la mayoría de ellos recursos pesqueros, aunque considera especies de la fauna acompañante de la pesquería industrial de cerco, fitoplancton, zooplancton, detritos y predadores tope. Se utiliza el modelo y paquete computacional Ecopath con Ecosim versión 5.1. Los parámetros de entrada para el área de estudio (18°20’S a 24°00’S y desde la costa hasta 60 mn al oeste, equivalente a 35.000 km² se obtuvieron desde literatura especializada y desde otros modelos aplicados a ecosistemas de surgencia. Los resultados indican que los flujos totales, que son una estimación del tamaño del ecosistema, alcanzan a 38.674 ton·km-2·año-1, mientras que la producción primaria estimada se calcula en 13.452 ton·km-2·año-1. El nivel trófico promedio de la pesquería del norte de Chile fue de 2,7, lo que refleja que las capturas se sostienen en especies de niveles trófico bajo, principalmente sardina (Sardinops sagax. La eficiencia de transferencia media de energía fue de 9,8%, valor que está dentro del rango característico de 10% calculado para ecosistemas marinos. Este ecosistema puede caracterizarse como un sistema que está alejado de la madurez, baja eficiencia de transferencia de energía, cadenas tróficas cortas y un bajo reciclaje de materia, lo que es consistente con lo informado para los principales ecosistemas de surgencias del mundoAn ecotrophic model was constructed to assess energy flows in the pelagic food web off northern Chile (18º20’S - 24º00’S; from the coast to 60 nm west; encompassing 35,000 km² in 1989. Required input parameters were obtained from the literature and other models applied to upwelling ecosystems. The model considered 13 functional groups

  18. Clockwise block rotations along the eastern border of the Cordillera de Domeyko, Northern Chile (22°45' 23°30'S)

    Science.gov (United States)

    Arriagada, César; Roperch, Pierrick; Mpodozis, Constantino

    2000-11-01

    We report new paleomagnetic results from a study of 38 sites in Cretaceous to Early Tertiary red beds and volcanic rocks belonging to the Purilactis Group, which outcrop along the western border of the Salar de Atacama Basin. After detailed thermal demagnetization, characteristic directions were determined for 32 units. In most cases, red bed sediments from the lower members of the Purilactis Group have a well-defined normal polarity magnetization probably carried by hematite forming an early diagenetic cement. A large decrease in the dispersion of the paleomagnetic directions upon tilt correction demonstrates that this magnetization is a pre-tectonic magnetization. We interpret the dominant occurrence of the normal polarity direction as evidence for acquisition of the magnetization during the Cretaceous normal polarity superchron. Large deviations of the paleomagnetic declinations from the expected ones for stable South America provides new evidence for clockwise tectonic rotations associated with Tertiary deformation in the Cordillera de Domeyko. These data confirm that clockwise tectonic rotations are one of the most significant structural characteristics of the north Chilean Andes. This study, however, indicates spatial variation in the magnitude of the rotation with rotations >60° in the Cerro Totola area. These rotations have occurred in conjunction with transpressional deformation that affected large tracts of the Cordillera de Domeyko during Eocene deformation. The systematic observation of clockwise rotations contemporaneous with sinistral displacements in the Cordillera de Domeyko can be explained by shear-traction at the base of the brittle crust.

  19. Ecología trófica de Girella laevifrons (Pisces: Kyphosidae en zonas intermareales rocosas del norte de Chile afectadas y no afectadas por contaminantes derivados de la minería del cobre Trophic ecology of Girella laevifrons (Pisces: Kyphosidae in rocky intertidal zones of northern Chile affected an non-affected by copper mine tailings

    Directory of Open Access Journals (Sweden)

    JOSE MIGUEL FARIÑA

    2000-03-01

    Full Text Available La zonas intermareales de localidades de la costa norte de Chile afectadas por contaminantes derivados de la minería del cobre, presentan una diversidad de especies sésiles menor que las localidades no afectadas. Girella laevifrons es un pez altamente representado en zonas intermareales rocosas del norte de Chile. En el presente trabajo se analiza y compara la ecología trófica de esta especie, en relación con las diferencias en la composición de especies sésiles de sitios contaminados y no contaminados. Los resultados muestran diferencias significativas en la composición trófica de los ejemplares presentes en los sitios afectados y no afectados. Dentro de los sitios afectados, se observan diferencias en los tamaños y en las concentraciones de cobre corporales, las cuales pueden estar relacionadas directamente con la disponibilidad de alimento e indirectamente con interacciones con otros organismos intermarealesThe intertidal zone at several sites of the northern Chilean coast affected by copper mine tailings, shows a lower diversity of sessile species than the non-affected ones. Girella laevifrons is a fish highly represented in rocky intertidal shores of these sites. In this study we analized and compared, the dietary composition of this species and its relation with the intertidal sessile assemblages of contaminated and non-contaminated sites. The results show significant differences in the dietary composition of the fishes occurring in contaminated and non-contaminated sites. Within the contaminated sites, the differences in body sizes and in the body concentrations of copper could be related directly to the food availability and indirectly to the interactions with other intertidal species

  20. Engineering masterpieces : from the Andes to Siberia, Canadian talent is in demand

    Energy Technology Data Exchange (ETDEWEB)

    Jaremko, G.

    2001-03-05

    Canadian oilfields are a prime breeding ground for talent, technology and industrial management. This paper described how Canadian talent was recognized in 2001 for three major projects which included a cold-ocean production platform in the Sea of Okhotsk in Siberia, a mountain pipeline project in South America, and an in-situ underground extraction technology in the oilsands of Alberta. The cold-ocean production platform project was recruited by Sakhalin Energy Investment Co., an international consortium originally led by Marathon Oil Co which is now led by Royal Dutch Shell. The oil production platform is stationed 16 kilometres offshore of Sakhalin Island in the Sea of Okhotsk. Sakhalin Energy bought and converted the Molikpaq, an innovative platform made in the 1980s for the Beaufort Sea by Gulf Canada Resources Ltd. The second project included Calgary's Hydroconsult EN3 Services Ltd. which was responsible for the construction of the 940-km GasAtacama 24-inch diameter pipeline between gas fields in northern Argentina and Chile through a 4,000 metre high mountain pass through the Andes. The formidable terrain meant that riverbeds were the only practical route. Pipeline was laid under the rivers, deep enough to escape the forces of wet-season runoff. During the construction, local irrigation systems were kept going with pumps. The final project involved an innovative technology known as steam assisted gravity drainage (SAGD) for enhanced recovery of the Alberta oilsands. Compared to strip-mining, SAGD has several advantages. The process separates the oil from the sand beneath the ground with paris of heat-injection and production wells. The system avoids the use of huge machinery, vast open pits and lake-size waste water ponds. The challenge is to ensure that environmental effects are monitored during the lifespan of any project. 6 figs.

  1. Comparative phylogeography of co-distributed Phrygilus species (Aves, Thraupidae) from the Central Andes.

    Science.gov (United States)

    Álvarez-Varas, R; González-Acuña, D; Vianna, J A

    2015-09-01

    The Neotropical ecoregion has been an important place of avian diversification where dispersal and allopatric events coupled with periods of active orogeny and climate change (Late Pliocene-Pleistocene) have shaped the biogeography of the region. In the Neotropics, avian population structure has been sculpted not only by geographical barriers, but also by non-allopatric factors such as natural selection and local adaptation. We analyzed the genetic variation of six co-distributed Phrygilus species from the Central Andes, based on mitochondrial and nuclear markers in conjunction with morphological differentiation. We examined if Phrygilus species share patterns of population structure and historical demography, and reviewed the intraspecific taxonomy in part of their geographic range. Our results showed different phylogeographic patterns between species, even among those belonging to the same phylogenetic clade. P. alaudinus, P. atriceps, and P. unicolor showed genetic differentiation mediated by allopatric mechanisms in response to specific geographic barriers; P. gayi showed sympatric lineages in northern Chile, while P. plebejus and P. fruticeti showed a single genetic group. We found no relationship between geographic range size and genetic structure. Additionally, a signature of expansion was found in three species related to the expansion of paleolakes in the Altiplano region and the drying phase of the Atacama Desert. Morphological analysis showed congruence with molecular data and intraspecific taxonomy in most species. While we detected genetic and phenotypic patterns that could be related to natural selection and local adaptation, our results indicate that allopatric events acted as a major factor in the population differentiation of Phrygilus species. PMID:25987531

  2. Charles Darwin in the Andes

    Science.gov (United States)

    Bizzo, Nelio; Bizzo, Luis Eduardo Maestrelli

    2006-01-01

    Considering geological time as an important epistemological obstacle to the construction of ideas on biological evolution, a study was carried out on the so-called "Darwin Papers". The conclusion was that Charles Darwin's excursion in the Andes during March-April 1835 was a crucial step in this regard. An expedition was carried out in March-April…

  3. Recording the transition from flare-up to steady-state arc magmatism at the Purico-Chascon volcanic complex, northern Chile

    Science.gov (United States)

    Burns, Dale H.; de Silva, Shanaka L.; Tepley, Frank; Schmitt, Axel K.; Loewen, Matthew W.

    2015-07-01

    The long-term evolution of continental magmatic arcs is episodic, where a few transient events of high magmatic flux or flare-ups punctuate the low-flux magmatism or "steady state" that makes up most of the arc history. How this duality manifests in terms of differences in crustal architecture, magma dynamics and chemistry, and the time scale over which transitions occur is poorly known. Herein we use multiscale geochemical and isotopic characteristics coupled with geothermobarometry at the Purico-Chascon Volcanic Complex (PCVC) in the Central Andes to identify a transition from flare-up to steady state arc magmatism over ∼800 kyr during which significant changes in upper crustal magmatic dynamics are recorded. The PCVC is one of the youngest volcanic centers related to a 10-1 Ma ignimbrite flare-up in the Altiplano-Puna Volcanic Complex of the Central Andes. Activity at the PCVC initiated 0.98 ± 0.03 Ma with the eruption of a large 80-100 km3 crystal-rich dacite ignimbrite. High, restricted 87Sr/86Sr isotope ratios between 0.7085 and 0.7090 in the bulk rock and plagioclase crystals from the Purico ignimbrite, combined with mineral chemistry and phase relationships indicate the dacite magma accumulated and evolved at relatively low temperatures around 800-850 °C in the upper crust at 4-8 km depth. Minor andesite pumice erupted late in the ignimbrite sequence records a second higher temperature (965 °C), higher pressure environment (17-20 km), but with similar restricted radiogenic bulk rock 87Sr/86Sr = 0.7089-0.7091 to the dacites. The compositional and isotopic characteristics of the Purico ignimbrite implicate an extensive zone of upper crustal mixing, assimilation, storage and homogenization (MASH) between ∼30 and 4 km beneath the PCVC ∼1 Ma. The final eruptions at the PCVC geothermal gradients and efficient crustal processing leading to a dominantly "crustal" magmatism feeding the large volume Purico ignimbrite. This upper crustal MASH zone would act

  4. Evolution of magmatism from the uppermost cretaceous to Oligocene, and its relationship to changing tectonic regime, in the Inca de Oro-El Salvador area (Northern Chile)

    International Nuclear Information System (INIS)

    We present geochronological and petrological data for extrusive and intrusive rocks in the Inca de Oro and El Salvador sheets (in prep.), and the Potrerillos (Tomlinson et al., 1999) and Salar de Maricunga sheets (Cornejo et al., 1998), III Region, Chile (26o-27o S). Most of these data were collected as part of the SERNAGEOMIN regional mapping programme. Additionally, we include published data for El Salvador and Potrerillos districts (Cornejo et al., 1997; Marsh et al., 1997; Gustafson et al., 2001). The dataset includes K/Ar, Ar/Ar and U-Pb mineral ages, which have been carefully selected for quality. The area is underlain by Carboniferous-Permian granitic basement rocks, which are covered by Triassic to Early Upper Cretaceous volcanic and sedimentary successions, including both marine and continental sequences (Cornejo et al., 1993). The period studied in this paper includes extrusive and intrusive rocks of Maastrichtian to Oligocene age, which are of particular interest since they record the 'preparation' of the lithosphere prior to, during, and after the mid-Eocene Incaic deformation and associated porphyry copper event. Shortening in the early-upper Cretaceous (95-85Ma; e.g. Mpodozis and Ramos, 1989; Arevalo and Grocott, 2000) deformed large areas of northen Chile, and marked the transition from the dominance of intra-arc extension to that of shortening punctuated by periods of extension. We recognise seven tectono-magmatic periods from the uppermost Cretaceous to Oligocene, comprising a volcanic sedimentary event contemporaneous with an extensional tectonic regime in the Upper Cretaceous, associated with graben formation, followed by an important compressive event at the beginning of the Tertiary. The middle Paleocene was again dominated by voluminous volcanic activity (collapse calderas) in an extensional regime. During the lowest Eocene the magmatic activity in the area shows a gradual transition from pyroxene-bearing to amphibole-bearing lithologies

  5. Estimation of Arsenic Intake from Drinking Water and Food (Raw and Cooked in a Rural Village of Northern Chile. Urine as a Biomarker of Recent Exposure

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    Oscar Pablo Diaz

    2015-05-01

    Full Text Available The aim of this study was to estimate both the contribution of drinking water and food (raw and cooked to the total (t-As and inorganic (i-As arsenic intake and the exposure of inhabitants of Socaire, a rural village in Chile´s Antofagasta Region, by using urine as biomarker. The i-As intake from food and water was estimated using samples collected between November 2008 and September 2009. A 24-hour dietary recall questionnaire was given to 20 participants. Drinking water, food (raw and cooked and urine samples were collected directly from the homes where the interviewees lived. The percentage of i-As/t-As in the drinking water that contributed to the total intake was variable (26.8–92.9. Cereals and vegetables are the food groups that contain higher concentrations of i-As. All of the participants interviewed exceeded the reference intake FAO/OMS (149.8 µg∙i-As·day−1 by approximately nine times. The concentration of t-As in urine in each individual ranged from 78 to 459 ng·mL−1. Estimated As intake from drinking water and food was not associated with total urinary As concentration. The results show that both drinking water and food substantially contribute to i-As intake and an increased exposure risk to adult residents in contaminated areas.

  6. Microevolution of human archaic groups of Arica, northern Chile, and its genetic contribution to populations from the Formative Period Microevolución de grupos humanos arcaicos de Arica, norte de Chile, y su contribución genética a las poblaciones del Período Formativo

    Directory of Open Access Journals (Sweden)

    HÉCTOR HUGO VARELA

    2006-06-01

    Full Text Available The microevolution of the archaic populations from Chile's northern coast and its morphological contribution to Formative period groups was studied. The sample comprised 181 individuals belonging to two Archaic (Morro-Uhle and Morro 1-1/6 and one Formative (Playa Miller-7 [Plm-7] series of the coast and one sample from the Formative (Alto Ramírez exhumed at the Azapa Valley. A total of 29 metric variables of the cranium were analyzed. Biological variability was assessed using discriminant analysis and Mahalanobis' D² distance stadistic (MDS. Population structure was inferred using a method based on quantitative genetic theory that predicts a lineal relationship between average within-group phenotypic variance and group distance to the population centroid. The four samples studied proved to be different from a morphologic point of view. The greatest distance was observed between Plm-7 (coast Formative and Alto Ramirez (valley Formative, the least between Morro-Uhle and Morro 1-1/6, the remaining distances presenting intermediate values. Regarding the total population, the most divergent group was Alto Ramírez and the least divergent was Morro1-1/6. A gradual biologic change was observed between Archaic (Morro Uhle and Morro 1-1/6 and coastal Formative populations (Plm-7 pointing to a morphological (genetic contribution of Archaic fishermen to Formative population of Chile's northern coast, without excluding gene flow from other groups of the South Central Andean AreaEstudiamos la microevolución de las poblaciones arcaicas de la costa norte y sus contribuciones morfológicas al Período Formativo. La muestra comprendió 181 individuos pertenecientes a dos colecciones arcaicas de la costa (Morro-Uhle y Morro 1-1/6 y una al formativo (Alto Ramírez exhumada en el Valle de Azapa. Un total de 29 variables métricas del cráneo fueron analizadas. La variabilidad biológica fue determinada utilizando análisis discriminante y distancias de

  7. A Younger Dryas glacierization in the Venezuelan Andes

    Science.gov (United States)

    Stansell, N. D.; Abbott, M. B.; Polissar, P. J.; Bezada, M.

    2007-12-01

    The Younger Dryas (YD) was an abrupt climate change event that has been well recorded in marine archives, but is still uncertain in terrestrial records from the tropics. For instance, the YD is recorded in the Cariaco Basin as an event of increased upwelling intensity and decreased terrigenous input; however continental records of a coincident climate change event across the region are inconclusive. Moreover, pollen data from the Colombian Andes suggest that there was a local cold stadial that coincides with the YD, but paleoenvironmental records from the Venezuelan Andes during the same time interval are not clear. Here we present a high-resolution late- glacial sequence from the Pico Espejo region of Venezuela. Our record is based on radiocarbon dated lake sediments that were analyzed using magnetic susceptibility, scanning X-ray fluorescence and loss-on-ignition methods. The sequence contains a period of increased glacial-sedimentary flux between ca. 13,000 and 12,000 cal yr BP, which coincides with the timing of the YD. Glacio-lacustrine sediments also increased between ca. 11,000 to 10,000 cal yr BP. Combined, these data suggest the northern tropical Andes experienced cooling events during the YD, and from ca. 11,000 to 10,000 cal yr BP.

  8. 78 FR 24228 - Lake Andes National Wildlife Refuge Complex, Lake Andes, SD; Final Comprehensive Conservation Plan

    Science.gov (United States)

    2013-04-24

    ... review and comment following the announcement in the Federal Register on October 29, 2012 ] (77 FR 65574... Fish and Wildlife Service Lake Andes National Wildlife Refuge Complex, Lake Andes, SD; Final... conservation plan and finding of no significant impact (FONSI) for the Lake Andes National Wildlife...

  9. Personajes fuera de lugar: antropomorfos tardíos en el arte rupestre del norte semiárido de Chile Images out of place: late period antropomorphous figures in the rock art of central Chile

    Directory of Open Access Journals (Sweden)

    Andrés Troncoso

    2011-07-01

    Full Text Available Los personajes con vestimenta son una de las representaciones rupestres más conocidas del noroeste argentino y el norte de Chile, y su presencia en ambas áreas es un indicador de la importante dinámica de interacción ocurrida durante el período Tardío entre ambos espacios. Una variedad de estos personajes son los antropomorfos con cuerpos de lados cóncavos (sensu Montt 2005, los que en ocasiones se representan asociados a escutiformes santamarianos. Si bien se ha planteado que su distribución meridional por la vertiente andina occidental no traspasa el área de San Pedro de Atacama (Montt 2005, en este trabajo presentamos tres diseños antropomorfos con cuerpo de lados cóncavos reconocidos en el arte rupestre del valle de Illapel (30° LS, Provincia del Choapa, Norte Semiárido de Chile. En particular, se establece un análisis formal de estos diseños y se los compara con aquellos reconocidos en zonas más septentrionales, para luego discutir su cronología y evaluar las implicancias de su presencia en espacios tan alejados a su área de distribución original, registro que se asocia, en la región, a la circulación de diseños establecida por el Tawantinsuyu.Anthropomorphous figures with clothing stand out among the most frequent representations in the rock art of Northwestern Argentina and Northern Chile. Their ubiquity in both areas has been considered as an indicator of the dynamics of interregional interaction during late prehistory. Antropomorphous with concave sides (sensu Montt 2005 are but one expression of these popular type of representations, and at least in some cases are associated with "shield-man" of the Santa María style. Even though it has been stated previously that for the western Cordillera de los Andes the southernmost dispersion of this type of anthropomorphous figure is the San Pedro de Atacama area (Montt 2005, in this paper we present three such figures recently recorded in the rock art of the Illapel valley

  10. A promising location in Patagonia for paleoclimate and paleoenvironmental reconstructions revealed by shallow firn core from Monte San Valentin (Northern patagonia Icefield, Chile)

    DEFF Research Database (Denmark)

    Vimeux, F.; de Angelis, M.; Ginot, P.;

    2008-01-01

    Southern Hemisphere. In this framework, a 15.3-m long shallow firn core has been extracted in March 2005 from the summit plateau of Monte San Valentín (3747 m, 46°35'S, 73°19'W) in the Northern Patagonia Icefield to test its potential for paleoclimate and paleoenvironmental reconstructions. The firn...... temperature is -11.9°C at 10-m depth allowing to expect well preserved both chemical and isotopic signals, unperturbed by water percolation. The dating of the core, on the basis of a multi-proxy approach combining annual layer counting and radionuclide measurements, shows that past environment and climate can...

  11. New Archaeological Evidence for an Early Human Presence at Monte Verde, Chile

    Science.gov (United States)

    Dillehay, Tom D.; Ocampo, Carlos; Saavedra, José; Sawakuchi, Andre Oliveira; Vega, Rodrigo M.; Pino, Mario; Collins, Michael B.; Scott Cummings, Linda; Arregui, Iván; Villagran, Ximena S.; Hartmann, Gelvam A.; Mella, Mauricio; González, Andrea; Dix, George

    2015-01-01

    Questions surrounding the chronology, place, and character of the initial human colonization of the Americas are a long-standing focus of debate. Interdisciplinary debate continues over the timing of entry, the rapidity and direction of dispersion, the variety of human responses to diverse habitats, the criteria for evaluating the validity of early sites, and the differences and similarities between colonization in North and South America. Despite recent advances in our understanding of these issues, archaeology still faces challenges in defining interdisciplinary research problems, assessing the reliability of the data, and applying new interpretative models. As the debates and challenges continue, new studies take place and previous research reexamined. Here we discuss recent exploratory excavation at and interdisciplinary data from the Monte Verde area in Chile to further our understanding of the first peopling of the Americas. New evidence of stone artifacts, faunal remains, and burned areas suggests discrete horizons of ephemeral human activity in a sandur plain setting radiocarbon and luminescence dated between at least ~18,500 and 14,500 cal BP. Based on multiple lines of evidence, including sedimentary proxies and artifact analysis, we present the probable anthropogenic origins and wider implications of this evidence. In a non-glacial cold climate environment of the south-central Andes, which is challenging for human occupation and for the preservation of hunter-gatherer sites, these horizons provide insight into an earlier context of late Pleistocene human behavior in northern Patagonia. PMID:26580202

  12. Glacial recession in the Tropical Andes from the Little Ice Age: the case of Ampato Volcanic Complex (Southern Peru

    Science.gov (United States)

    Alcalá, J.; Palacios, D.; Zamorano, J. J.

    2010-03-01

    Data published over the last decade reveal substantial glacial recession in the tropical Andes since the Little Ice Age (LIA), (Ramirez, et al., 2001; Rabatel, et al., 2005; Rabatel, et al., 2008; Vuille, et al., 2008; Hastenrath, 2009; Jomelli, et al., 2009), and a growing rate of recession since the 1980’s caused by global warming (Ramirez, et al., 2001; Vuille, et al., 2008). Today there is great interest in the evolution of these ice masses due to heightened awareness of climate change and of the strategic importance that glaciers have as a hydrologic resource for communities in arid climate zones in the tropical Andes (Mark, 2008; Vuille et al., 2008). Cordillera Blanca forms part of the Andes Mountains of northern Peru, and is a chosen site for many studies on glacier evolution. Vuille et al. 2008 determined that a considerable area of ice mass was lost at Huascarán-Chopicalqui glacier (18% from 1920-1970) and Astesonraju glacier (20% from 1962-2003). Studies at Coropuna volcano, which has the most extensive glacier field in the western range of southern Peru, also report a strong melting trend that began with only minimal recession from 1955-1986 (4%), but increased to 14% from 1986-2007 (Úbeda et al., 2009). Only a few of the Andes glaciers are consistently monitored, and the most comprehensive data are for Chacaltaya and Zongo glaciers (16º S) in Bolivia. Since the maximum LIA, Chacaltaya has lost 89% of its surface area, particularly in recent years. By 1983, the totaled loss was five times the shrinkage for the period 1940-1963 (Ramirez, et al., 2001). Zongo glacier maintained equilibrium from 1956-1975, but later experienced a period dominated by continuous recession (Soruco, et al., 2009). This study expands current knowledge of glacier evolution since the LIA in the Central Volcanic Zone (CVZ; 14º - 27º S) (Stern, 2004) of the Andes. The study site was chosen in an area that had never been used for preliminary research of this type, concretely

  13. Caracterización trófica del placóforo intermareal Enoplochiton niger en el norte de Chile: variación ambiental y patrones dietarios a nivel local y region Trophic characterization of the intertidal placophoran Enoplochiton niger in northern Chile: environmental variation and dietary patterns at local and regional levels

    Directory of Open Access Journals (Sweden)

    ALVARO G SANHUEZA

    2008-12-01

    .The role and impact of herbivores on rocky intertidal food webs could be more complex and diverse than previously considered, particularly in the case of larger and more abundant consumers such as the placophoran mollusc Enoplochiton niger. This species is one of the largest (up to 20 cm and ecologically most important grazers on rocky shores of northern Chile, but also one of the lesser known species in trophic terms. This work presents an assessment of the dietary patterns of E. niger in four communities of northern Chile, distributed along 1,000 km of coastline and sampled seasonally from winter 2004 to autumn 2006. The analysis included the relationship of its diet with physical and biological factors, and particularly the potential effect of the 2004-2005 El Niño event that occurred during the study period. At a regional level, the dietary spectrum of E. niger comprised a total of 98 food resources (60 algal Ítems and 38 invertebrate Ítems, and the most important Ítems were sessile organisms of encrusting and layer-forming growth habits. E. niger exhibited a very high niche breadth at both local and regional levels (ranging from 20.7 to 28.0; Levins' index, and its dietary richness at the individual level was independent from its body size. Both the number of dietary ítems consumed per individual and the taxonomic composition of the diet did not show statistical differences among communities, but they were significantly different between the El Niño and non-El Niño periods. There was no clear relationship between the dietary patterns of E. niger and the contrasting levels of upwelling intensity among the communities studied. The results show that E. niger is a generalist polyphagous consumer, and a potential omnivore, which could have a high level of impact on space occupancy patterns in the intertidal community.

  14. Heinrich I and Younger Dryas Glaciation in the Central Andes

    Science.gov (United States)

    Zech, J.; Zech, R.; May, J.; Kubik, P. W.; Veit, H.

    2009-12-01

    Short term climate reversals, such as Heinrich I (H-I) and the Younger Dryas (YD), are well documented in the Northern Hemisphere. However, the respective response of the climate system in the Southern Hemisphere during these events remains enigmatic. Here we present 10Be surface exposure ages from the Wara Wara Valley (17°S, 66°W), Cordillera Cochabamba, that reveal glacial advances in the Central Andes before 14.3 ka and 11.9 ka. These advances correlate with H-I and YD and coincide with the lake transgression phases Tauca (18-14 ka) and Coipasa (13-11 ka) on the Altiplano. They corroborate the precipitation sensitivity of glacier mass balances in the semi-arid Central Andes. We suggest that sufficient moisture for glacial advances can be explained by enhanced upper tropospheric easterlies as a response to an intensified tropical circulation and sustained la Niña like patterns in the eastern Pacific. This redistribution of the ocean and atmospheric circulation was caused by a southward shift of the ITCZ due to northern hemispheric cooling. At 10.8 ka glacier advanced again attributed to increased moisture supply by enhanced polar advection and SE trade winds during the Early Holocene. Final deglaciation started only at 9.2 ka induced by a change to drier conditions.

  15. Variabilidad estacional de la distribución y abundancia de larvas de langostino colorado en la zona norte de Chile (Decapoda, Anomura, Galatheidae Seasonal variability in the distribution and abundance of larvae of the red squat lobster (Decapoda, Anomura, Galatheidae from Northern Chile

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    Jorge Rivera

    2005-05-01

    Full Text Available Se analiza la distribución y abundancia de los estadios larvales de langostino colorado Pleuroncodes monodon en la zona norte de Chile, capturados entre 0 y 100 m, en cuatro cruceros oceanográficos efectuados en enero, mayo, agosto y octubre de 2003, en un área adyacente a la desembocadura del río Loa (20°40'-21°20'S. Se realizó un total de 20 estaciones oceanográficas y las muestras zooplanctónicas se obtuvieron mediante redes Bongo desde la superficie hasta 100 m de profundidad, registrándose además datos de temperatura, oxígeno disuelto y densidad en cada estación. Los máximos de abundancia se registraron en enero y agosto, y el mínimo en mayo. En sentido norte-sur, las mayores abundancias se encontraron en las secciones situadas en el sector norte. No obstante, en octubre se observó una distribución de abundancia más homogénea. En sentido costa-océano se determinó un patrón diferenciado, con una preferencia oceánica de los estadios zoea III-V y megalopa. Además, se observó una tendencia estacional de los focos de mayor abundancia larvaria asociados a las estaciones con temperaturas medias de 14,0-16,0°C y a concentraciones medias de oxígeno disuelto de 1,58-4,55 mL·L-1An analysis was made of the distribution and abundance of red squat lobster (Pleuroncodes monodon larvae off the mouth of the Loa River, northern Chile (20°40'-21°20'S during oceanographic cruises in January, May, August and October 2003. A total of 20 oceanographic stations were occupied, with zooplankton samples taken using Bongo nets towed from the surface to 100 m depth. Other data obtained at each station included temperature, dissolved oxygen, and seawater density. Maxima of abundance of these larvae were recorded in January and August, with a minimum in May. On N-S tracks the highest abundances were recorded in the northern sector. A more homogeneous distribution of abundance was observed in October. On E-W tracks a differentiated pattern

  16. The High Andean Cordillera of central Argentina and Chile along the Piuquenes Pass-Cordon del Portillo transect: Darwin's pioneering observations compared with modern geology La Alta Cordillera de los Andes del centro de Argentina y Chile a lo largo de la transecta del Paso Piuquenes-Cordón del Portillo: Las observaciones pioneras de Darwin comparadas con la geología moderna

    Directory of Open Access Journals (Sweden)

    Laura Giambiagi

    2009-04-01

    Full Text Available The geological observations made by Darwin in 1835 during his crossing of the Andes from Santiago to Mendoza via the Piuquenes Pass and Cordón del Portillo are compared with the present geological knowledge of the Cordillera Principal and Cordillera Frontal at 33°-34°S. The analysis of the complex stratigraphy of the Cordillera Principal, the imbricated structure of the Aconcagua fold and thrust belt, as well as the stratigraphy and structure of the inter mountain foreland Tunuyán Basin, allows to assess the pioneer observations of Darwin. He recognized the old metamorphic basement and the granitoids and volcanic sequences of late Paleozoic to Triassic age of the Cordillera Frontal, established the Cretaceous age of the marine successions cropping out along the eastern Cordillera Principal and studied the conglomeratic deposits associated with the uplift of the Cordillera in the Alto Tunuyán Basin. Based on the study of clast provenance of the synorogenic deposits of the Alto Tunuyán Basin, Darwin recognized that the Cordillera Frontal was uplifted later than the Cordillera Principal. The present knowledge of this sector of the Andean Cordillera confirms his pioneer observations and show that Darwin was one of the first scientists ever in realizing that in an orogenic system the sequence of uplift and deformation proceeds from hinterland towards foreland, according to a process that is exceptionally well-illustrated along the Piuquenes-Cordón del Portillo transect.Las observaciones geológicas efectuadas por Darwin en 1935 durante su cruce de la Cordillera de Los Andes entre Santiago y Mendoza realizado en 1835 a través de los pasos del Portillo y Piuquenes son examinadas y comparadas con el conocimiento actual existente de las Cordilleras Principal y Frontal entre los 33°-34°S. El análisis de la compleja estratigrafía de la Cordillera Principal, la estructura de las diferentes láminas imbricadas de la faja plegada y corrida del

  17. Orographic barriers, high-resolution TRMM rainfall, and relief variations along the eastern Andes

    Science.gov (United States)

    Bookhagen, B.; Strecker, M. R.

    2007-12-01

    The complex interplay between erosion and tectonics shapes landscapes on various time and length scales. Thus, determining the relative importance of tectonic and climate-driven processes is key for our understanding of the evolution of tectonically active mountain belts. Each mountain belt may exhibit an individual and complex response to these processes that may be characteristic for differently sized sectors of the orogenic system. Here, we focus on small (101km) to medium (102-103km) scale relations along the eastern flank of the meridionally oriented South American Andes. The central Andes and the major part of the northern Andes are subject to strong rainfall and erosion on their eastern side. There, rainfall has a strong gradient with wet, northern and central parts and presently drier areas south of the Andes bend at ~17°S. While lithology and geologic units vary along strike, the general deformation regime of the northern and central eastern Andes is similar with east vergent thrust-fault systems. We use high-resolution Tropical Rainfall Measurement Mission (TRMM) and SRTM topographic data to characterize elevation, relief, and hillslope angle of peak rainfall at orographic barriers constituting the eastern flank of the orogen. Over a distance of more than 3500km along the eastern flank of the Andes facing the Amazon Basin, we find that peak rainfall (>3.5m/yr) occurs at a mean elevation of 1.3±0.17km, a mean 3- km-relief of 0.95±0.08km, and areas characterized by moderate mean hillslope angles of 18.3±1.7°. We find that topographic relief is the best first-order rainfall predictor. South of the eastward-convex bend of the Andes, rainfall amounts decrease and there exists no distinct, high rainfall peak. The reduction in rainfall is accompanied by a reduction of relief involving several hundred meters at the mountain front as rivers exiting the eastern Andes tend to form large sedimentary fan systems that reduce the distance between minimum and

  18. Quinua in Chile

    OpenAIRE

    Martinez, Enrique A.; Fuentes, Francisco F.; Chia, Eduardo; Namdar-Irani, Mina; Olguin, Pablo; Saa, Constanza; Thomet, Max; Vidal, Alejandra

    2015-01-01

    The biogeography of quinoa (Chenopodium quinua Willd.) provides a comprehensive view of a crop that is relatively minor in Chilean agriculture, despite growing in a large geographical area (18°–47°S). Quinoa’s genetic diversity illustrates that it is a vital crop in the South American Andes region. It was domesticated in various geographical zones, which generated a wide variety of adaptative morphological and environmental features. Specific adaptations in each macrozone throughout the Andes...

  19. Heterogeneous density-structure of the northern Chile marine fore-arc and its relation to the rupture of the 2014 Mw8.2 Iquique earthquake

    Science.gov (United States)

    Maksymowicz, Andrei; Ruiz, Javier; Contreras-Reyes, Eduardo

    2016-04-01

    gravity and the northern limit of the earthquake correlates with the location of a relatively high local gravity anomaly. This local gravity high corresponds to the southern border of the well developed Arica marine forearc basin. The models show that the frontal portion of the continental wedge in the studied area is formed by low density material that is interpreted as fractured rock. The location of the foreshocks suggests that the presence of this highly fractured material is related to the location of the rupture updip and the stress accommodation process after the earthquake. The results show that detailed studies of the forearc gravity signal provide information of the structures that can play a key role in the earthquakes along the current seismic gaps to the north and to the south of Iquique earthquake.

  20. Feeding and nutritional ecology of the edible sea urchin Loxechinus albus in the northern Chilean coast Ecología nutricional y alimenticia del erizo comestible Loxechinus albus en el norte de Chile

    Directory of Open Access Journals (Sweden)

    SOLANGE J GONZÁLEZ

    2008-12-01

    Full Text Available The red sea urchin Loxechinus albus, an economically important species oceurring along the Chilean littoral benthic systems, has been heavily exploited by artisanal fisheries in recent decades. However, basic knowledge of its trophic biology is still scarce. Studies of this kind are critical to the successful development of farming techniques as an alternative to the harvest of natural populations. The aims of this study were to quantify the composition of L. albus' natural diet, to determine the assimilation efficieney of the most important dietary components, and to experimentally examine the species' trophic selectivity. Adult and juvenile specimens were sampled in spring 1993 and summer, fall and winter 1994 from the shallow subtidal zone of Iquique, northern Chile. Neither juveniles ñor adults showed significant seasonal differences in dietary composition. The main Ítems in the diet were the green alga Ulva sp. for juveniles and the kelp Lessonia sp. for adults. In adults, assimilation efficieney (as percentage of the total organic matter ingested was not significantly different among individuals that consumed Lessonia sp. (48.7 %, Ulva sp. (44.6 % and Macrocystis (38.1 %, whereas in juveniles assimilation efficieney was significantly higher for individuals fed on the chlorophyte Ulva sp. (55.4 %, followed by Lessonia sp. (35.0 % and Macrocystis (25.5 %. These results suggest that L. albus undergoes an ontogenetic shift in the diet, consisting of a differential foraging strategy between juveniles and adults.El erizo Loxechinus albus (Molina, 1782 es un recurso de gran importancia económica en los sistemas bentónicos costeros, y que se encuentra bajo una fuerte presión de explotación. Sin embargo, los antecedentes sobre diversos aspectos básicos de su biología trófica son aún escasos. Estudios de esta naturaleza son importantes en razón a que constituyen la base para el desarrollo de técnicas de cultivo exitosas, alternativa a la

  1. Structural analysis and shape-preferred orientation determination of the mélange facies in the Chañaral mélange, Las Tórtolas Formation, Coastal Cordillera, northern Chile

    Science.gov (United States)

    Fuentes, Paulina; Díaz-Alvarado, Juan; Fernández, Carlos; Díaz-Azpiroz, Manuel; Rodríguez, Natalia

    2016-04-01

    This study sheds light on the tectonic and structural knowledge of the mélange facies located to the south of Chañaral city, Chile. The Chañaral mélange has been related to an accretionary prism at the western active continental margin of Gondwana. Based on the fossil content, the original turbidite sequence would have been deposited during Devonian to Carboniferous times. The Chañaral mélange is included in the Las Tórtolas Formation, which corresponds to the Paleozoic metasedimentary basement located in the Coastal Range in northern Chile. It consists of a monotonous sequence of more than 90% of interbedded sandstones and shales, with a few limestones, pelagic chert, conglomerates and basic volcanic rocks, metamorphosed to the greenschist facies. In the study area, the Las Tórtolas Formation is divided into two structural domains separated by a major reverse dextral structure, called here the Infieles fault. To the east, the Las Tórtolas Formation is characterized by a brittle-ductile deformation, defined by the original sedimentary contacts in the turbiditic sequence. Besides, thrust faults and associated thrust propagation folds promotes a penetrative axial plane foliation. Mélange facies are located to the west of the Infieles fault. Although lithologies comprising this domain are similar to the rest of the Las Tórtolas Formation, mélange facies (ductile domain) are characterized by the complete disruption of the original architecture of the turbidite succession. The most significant structures in the mélange are the ubiquitous boudinage and pinch and swell structures, asymmetric objects, S-C structures and tight to isoclinal folds. This deformation is partitioned in the Chañaral mélange between linear fabric domains (L), characterized by quartzite blocks with prolate shape in a phyllite matrix with pencil structures, and linear-planar fabric domains (L-S), where quartzite objects show oblate shape and phyllites present a penetrative foliation

  2. Long-term denudation rates from the Central Andes (Chile estimated from a Digital Elevation Model using the Black Top Hat function and Inverse Distance Weighting: implications for the Neogene climate of the Atacama Desert Tasas de denudación de largo tiempo en los Andes Centrales, Chile, estimadas a partir de un modelo digital de elevación usando la función 'Top Hat' por cierre y la interpolación ponderada por el inverso de la distancia: implicancias del clima Neógeno del Desierto de Atacama

    Directory of Open Access Journals (Sweden)

    Rodrigo Riquelme

    2008-01-01

    Full Text Available A methodology for determining long-term denudation rates from morphologic markers in a Digital Elevation Model (DEM is checked by a comparative study of two drainage basins in the PrecordiUera of the Central Andes. In both cases the initial configuration of an incised pediment surface has been restored by using two different methods: the Black Top Hat (BTH function and the Inverse Distance Weighting (IDW interpolation. Where vertical incision and hillslope erosion are recorded, the IDW appears to be the most adequate to reconstitute the pediment surfaces. Conversely, where only vertical incision is observed, the BTH describes more precisely the former pediment surfaces and it is easier to solve. By subtracting the DEM from the reconstructed marker we calculated an eroded volume, and estimated its uncertainty by considering Root Mean Square Error (RMSE and DEM grid error. For the last ~10 Myr we obtained long-term denudation rates of 7.33±1.6 m/Myr in the San Andrés drainage basin and 13.59±1.9 m/Myr in the El Salado drainage basin. These estimations are largely in agreement with other reported estimates of long-term denudation rates in the Atacama Desert. Comparison with long-term denudation rates reported in a wide range of climatic regimes suggests that our estimates cannot be explained by the current rainfall in the PrecordiUera. However they could be explained by a rainfall similar to that reported 40 km to the east in the Puna. This suggests that during the time span concerned the geomorphologic evolution of the study area, this evolution is dominated by an orographically controlled rainfall pattern. The preserved pediment surface and the small long term denudation rates determined in this study also indicate that the PrecordiUera was never reached by humid tropical air masses and precipitation as currently observed in the Altiplano during the summer monthsUna metodología para determinar tasas de denudación de largo tiempo a partir de

  3. Estandarización de tasas de captura de pesquerías pelágicas de la zona norte de Chile durante 1987-92 Standardization of catch rates for the northern Chile pelagic fishery during 1987-92

    Directory of Open Access Journals (Sweden)

    Eleuterio Yáñez R.

    1999-01-01

    Full Text Available Se usó el modelo lineal general para estandarizar el índice de abundancia relativa, captura por unidad de esfuerzo (CPUE, de anchoveta (Engraulis ringens y sardina (Sardinops sagax en el norte de Chile (18º21'-24ºS, entre 1987 y 1992. Para anchoveta se toma en cuenta la categoría de embarcación, la zona de pesca, la estación del año, el año y la temperatura superficial del mar (TSM. Para sardina se considera la categoría de embarcación, la zona de pesca, la estación del año y el año. Estas variables muestran en general efectos bastante significativos en el logaritmo de la CPUE. Además, interacciones significativas son identificadas para anchoveta entre año*estación, año*zona, estación*zona, zona*TSM, estación*año*zona, estación*año*TSM, estación*zona*TSM y año*zona*TSM. Para sardina las interacciones significativas identificadas son estación*año, estación*zona, año*zona y estación*año*zona. En conclusión, cerca del 35% y 45% de la variación total observada de la CPUE no fueron explicadas por los modelos planteados para ambas especies, debido probablemente al carácter aleatorio de la pescaWe used a general linear model for the standarization of the index of relative abundance catch per unit of effort (CPUE. The analysis was performed for anchovy (Engraulis ringens and sardine (Sardinops sagax in northern Chile (18º21'-24ºS, for the years 1987 through 1992. For anchovy we have considered ship hold capacity, fishing area, season, year and the sea surface temperature (SST. For sardine, we have considered ship's hold capacity, fishing area, season and year. These variables individually have a significant effect in the CPUE logarithms. For the anchovy, we identified a significant interaction between year*season, year*fishing area, season*fishing area, fishing area*SST, season*year*fishing area, season*year*SST, season*fishing area*SST, and year*fishing area*SST. In the case of the sardine the significant

  4. Análisis bioeconómico de la pesquería de sardina (Sardinops sagax y anchoveta (Engraulis ringens de la zona norte de Chile Bioeconomic analysis of Pacific sardine (Sardinops sagax and anchovy (Engraulis ringens fishery from northern Chile

    Directory of Open Access Journals (Sweden)

    Bernardo Aliaga R.

    2001-01-01

    Full Text Available Se analizó bioeconómicamente la pesquería pelágica industrial de sardina y anchoveta de la zona norte de Chile, integrando información biológico-pesquera (período 1980-1991 y económica (período 1988-1995 mediante el modelo Gordon-Schaefer. Los datos económicos indican que los costos totales de la flota y las plantas de proceso mostraron una tendencia general decreciente durante el período estudiado. En cuanto a las inversiones, es posible identificar dos etapas: de 1988 a 1990 con un moderado aumento de las inversiones, y de 1992 a 1995, con una caída de la inversión neta explicable por la baja en los rendimientos físicos de la producción de harina, la caída en las capturas globales de la pesquería y la caída en el tipo de cambio. Los puntos de referencia biológicos y económicos determinados con el modelo Gordon-Schaefer, muestran que la flota ha operado utilizando un esfuerzo mayor al correspondiente en el punto de máximo rendimiento económico (E MRE y en el punto de equilibrio de libre acceso (E LA, en tanto que las capturas han sobrepasado el Máximo Rendimiento Sustentable (MRS. Se discuten estos resultados en términos de las limitaciones del modelo teórico al tratar de explicar el comportamiento de la flota en esta pesquería para el período analizado, bajo condiciones de integración vertical en la actividad económica. De resultar efectiva esta hipótesis, modelos bioeconómicos más complejos estarían sujetos a idéntica limitación, al no representar adecuadamente la racionalidad económica integrada de la empresa pesquera industrial. Se proponen futuras líneas de trabajo en esta temáticaThe industrial pelagic fishery of pacific sardine and anchovy from northern Chile was analysed through a bioeconomic approach including statistical data from the fishery (catch and effort between 1980 and 1991 and economic data (costs, revenues, investment and employment between 1988 and 1995 using a Gordon-Schaefer model

  5. Estructura térmica superficial del mar asociada a la distribución espacio-temporal de sardina y anchoveta en la zona norte de Chile entre 1987 y 1992 Sea surface thermal structure associated to the space-temporal distribution of sardine and anchovy in northern Chile

    Directory of Open Access Journals (Sweden)

    Eleuterio Yáñez R

    1995-01-01

    Full Text Available Utilizando un sistema de información geográfica (SIG, se analizan los cambios de la estructura térmica superficial del mar asociados a las variaciones espaciales y mensuales de sardina (Sardinops sagax y anchoveta (Engraulis ringens, en la zona norte de Chile (18°21'-24°00'S entre 1987 y 1992. Para tal efecto se toma en cuenta el índice de abundancia CPUE, estimado para ambas especies a partir de la información de una flota cerquera industrial. y datos de temperatura superficial del mar (TSM recolectados con satélites NOAA. Además se analizan datos de TSM y nivel del mar de estaciones de mareógrafos, y de viento e insolación de estaciones meteorológicas. En 1987 y 1992 la TSM presenta anomalías positivas asociadas a eventos El Niño, en tanto que 1990 se presenta como el año más frío del período de estudio. Se destaca la marcada señal anual de la TSM, con una estación cálida entre noviembre y abril, mientras que entre julio y septiembre se registran las TSM más bajas. Al comparar las distribuciones anuales de CPUE se determinan diferencias significativas entre ambas especies. A su vez, cada especie presenta distribuciones de CPUE diferentes entre años. Las dos especies presentan un patrón de migración norte-sur de la estación fría a la estación cálida, el cual se alteraría cuando se producen fuertes anomalías de TSMIn order to establish the space-temporal variability of the distribution of the sardine (Sardinops sagax and the anchovy (Engraulis ringens in association with the sea surface thermal structure in northern Chile (18°21'-24°00'S, a study was conducted with satellite and fisheries data between 1987 and 1992. Information was processed by using a geographic information system (GIS. Variables considered in the analysis included the abundance index CPUE as estimated for both species from a purse seine industrial fleet data, satellite records of sea surface temperature (SST, tidal gauge temperature and sea

  6. Concentración de metales pesados (Cu, Ni, Zn, Cd, Pb en la biota y sedimentos de una playa artificial, en la bahía San Jorge 23°S, norte de Chile Heavy metals concentration (Cu, Ni, Zn, Cd, Pb, in biota and sediments of an artificial beach, in San Jorge bay 23°S, northern Chile

    Directory of Open Access Journals (Sweden)

    Gabriel Castro

    2012-07-01

    Full Text Available Se evaluó el contenido de metales pesados (Cu, Ni, Zn, Cd, Pb en la biota y el sedimento de una playa artificial (Paraíso y una playa natural (El Lenguado, ubicadas en la bahía San Jorge, norte de Chile. Los resultados fueron utilizados para comparar ambos sistemas, el grado de cumplimiento de la normativa ambiental nacional e internacional, y el efecto de la construcción de la playa artificial sobre el nivel de contaminación por metales existentes históricamente en esa zona. En cada playa se ubicaron estaciones equidistantes que abarcaron desde el intermareal hasta el submareal de las cuales fueron extraídos los organismos. Se tomaron muestras de sedimento en cada playa y se determinaron las pendientes con el método de Emery. El análisis granulométrico evidenció el predominio de arena media en playa El Lenguado, y arena media y fina en playa Paraíso. El contenido de materia orgánica fue mayor en El Lenguado. En playa Paraíso se determinaron cinco phylum/superclase agrupados en 19 taxa, mientras que en El Lenguado se encontraron cuatro phylum/superclase agrupados en cc taxa. El contenido de metales en sedimentos y en la mayoría de organismos presentó valores mayores en playa Paraíso. Estos resultados, junto a las normas de calidad chilenas y norteamericanas, sugieren un evidente deterioro en la calidad ambiental de playa Paraíso lo que se demostró por un incremento en las concentraciones de estos metales desde su construcción, los que sobrepasan los límites establecidos por ambas normas.It was evaluated the heavy metal content (Cu, Ni, Zn, Cd, Pb in biota and sediment of an artificial beach (Paraíso and a natural beach (El Lenguado, both located in San Jorge bay, northern Chile. The results were used to compare both systems, the degree of fulfillment of national and international environmental regulations, and the effect of the construction of the artificial beach on the level of metal contamination historically existing in

  7. Eocene to Pleistocene lithostratigraphy, chronostratigraphy and tectono-sedimentary evolution of the Calama Basin, northern Chile Litoestratigrafía, cronoestratigrafía durante el Eoceno al Pleistoceno y evolución tectono-sedimentaria de la Cuenca de Calama, norte de Chile

    Directory of Open Access Journals (Sweden)

    Geoffrey May

    2005-01-01

    Full Text Available New 40Ar/39Ar radiometric, sedimentological and structural data from post-Paleocene sedimentary strata in the Calama Basin, northern Chile suggest that the established lithostratigraphy of the basin-fill requires revision. A new lithostratigraphic scheme for the Eocene-Pleistocene stratigraphy of the Calama Basin is proposed here. The key features of this scheme are that the existing Calama Formation is retained although the age of the formation is redefined as (?Lower Eocene to (?Lower Miocene. The El Loa Formation is elevated to group status and redefined as Lower Miocene to Upper Pliocene in age. The El Loa Group includes four newly defined formations: the Jalquinche, Opache, Lasana and Chiquinaputo formations. The existing definition of the uppermost unit within the Calama Basin, the Upper Pliocene to Pleistocene Chiu-Chiu Formation, is retained. The tectono-sedimentary evolution of the Calama Basin-fill reveals three distinct unconformity-bounded phases of sedimentation: Eocene-Oligocene, early Miocene to late mid-Miocene and late Miocene to late Pliocene. Sedimentation commenced in the Eocene with deposition of alluvial braidplain deposits (Calama Formation. This style of sedimentation occurred across northern Chile throughout the Oligocene following the Incaic Orogeny. From 22 Ma to 10 Ma ephemeral fluvial sediments were developed along the Calama Basin flanks (Lasana Formation, playa sandflat and mudflat deposits (Jalquinche Formation in the basin centre. Equivalently-aged sediments in both the Salar de Atacama and Pampa del Tamarugal basins also indicate deposition in endorheic basins. Late Miocene sedimentation occurred diachronously across the north Chilean forearc. The Pampa del Tamarugal and Calama Basin areas were linked around 6 Ma following tectonic activity. Regional palustrine carbonate sedimentation occurred in the Calama Basin centre (Opache Formation with fluvial sedimentation along the eastern basin margin (Chiquinaputo

  8. Spatio-temporal variability of snow water equivalent in the extra-tropical Andes cordillera from a distributed energy balance modeling and remotely sensed snow cover

    Science.gov (United States)

    Cornwell, E.; Molotch, N. P.; McPhee, J.

    2015-09-01

    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

  9. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 1997 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1997 calendar year. The report begins...

  10. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : Updated- 2003 annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 2003 calendar year. The report begins...

  11. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 1996 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1996 calendar year. The report begins...

  12. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 1999 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1999 calendar year. The report begins...

  13. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 1994 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1994 calendar year. The report begins...

  14. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 1995 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1995 calendar year. The report begins...

  15. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 1998 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1998 calendar year. The report begins...

  16. Lake Andes National Wildlife Refuge Complex : Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, Lake Andes Wetland Management District : 2000 Annual narrative report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 2000 calendar year. The report begins...

  17. Long term low latitude and high elevation cosmogenic 3He production rate inferred from a 107 ka-old lava flow in northern Chile; 22°S-3400 m a.s.l.

    Science.gov (United States)

    Delunel, Romain; Blard, Pierre-Henri; Martin, Léo C. P.; Nomade, Sébastien; Schlunegger, Fritz

    2016-07-01

    Available geological calibration sites used to estimate the rate at which cosmogenic 3He is produced at the Earth's surface are mostly clustered in medium to high latitudes. Moreover, most of them have exposure histories shorter than tens of thousands of years. This lack of sites prevents a qualitative assessment of available production models used to convert cosmogenic 3He concentrations into exposure ages and/or denudation rates. It thus limits our ability to take into account the atmospheric, geomagnetic and solar modulation conditions that might have affected the production of cosmogenic nuclides in the past for longer exposure histories and in low latitude regions. We present the cosmogenic 3He production rate inferred from a new geological calibration site located in northern Chile. Five samples were collected on the surface of the largest and best-preserved lava flow of the San Pedro volcano (21.934°S-68.510°W-3390 m a.s.l.), which displays pristine crease-structure features. 40Ar/39Ar dating yields a reliable plateau age of 107 ± 12 ka for the eruption of this lava flow. Eight pyroxene aliquots separated from the surface samples yield a weighted average cosmogenic 3He concentration of 99.3 ± 1.2 Mat g-1 from which a local cosmogenic 3He production rate of 928 ± 101 at g-1 yr-1 is calculated. The local production rate is then scaled to a sea level high latitude (SLHL) reference position using different combinations of geographic spatialization schemes, atmosphere models and geomagnetic field reconstructions, yielding SLHL production rates between 103 ± 11 and 130 ± 14 at g-1 yr-1 consistent with the most recent estimates available from the literature. Finally, we use the same scaling frameworks to re-evaluate the mean global-scale cosmogenic 3He production rate in olivine and pyroxene minerals at 120 ± 16 at g-1 yr-1 from the compilation of previously published calibration datasets.

  18. Lake Andes NWR Water Use Report- 1961

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1961. Existing water supplies are tabulated for each of the four units providing numbers for...

  19. Lake Andes NWR Water Use Report- 2009

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 2009. Short forms are supplied for the years water use report management plan. These forms cover...

  20. Lake Andes NWR Water Use Report- 1988

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1988. General water uses are discussed for 1988 for each unit, impoundment data is tabulated...

  1. Lake Andes NWR Water Use Report- 2013

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 2013. Short forms are supplied for the years water use report management plan. These forms cover...

  2. Lake Andes NWR Water Use Report- 1998

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1998. General water uses are discussed for 1998 for each unit, impoundment data is tabulated...

  3. Lake Andes NWR Water Use Report- 1964

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1964. Existing water supplies are tabulated for each of the four units providing numbers for...

  4. Lake Andes NWR Water Use Report- 1989

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1989. General water uses are discussed for 1989 for each unit, impoundment data is tabulated...

  5. Lake Andes NWR Water Use Report- 2006

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 2006. Short forms are supplied for the years water use report management plan. These forms cover...

  6. Lake Andes NWR Water Use Report- 2000

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 2000. General water uses are discussed for 2000 for each unit, impoundment data is tabulated...

  7. Lake Andes NWR Water Use Report- 1982

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1982. General water uses are discussed for 1982 for each unit, impoundment data is tabulated...

  8. Lake Andes NWR Water Use Report- 1984

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1984. General water uses are discussed for 1984 for each unit, impoundment data is tabulated...

  9. Lake Andes NWR Water Use Report- 1966

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1966. General water uses are discussed for 1966 for each unit, impoundment data is tabulated...

  10. Lake Andes NWR Water Use Report- 1963

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1963. Existing water supplies are tabulated for each of the four units providing numbers for...

  11. Lake Andes NWR Water Use Report- 2008

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 2008. Short forms are supplied for the years water use report management plan. These forms cover...

  12. Lake Andes NWR Water Use Report- 1959

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1959. Appears to just be the correspondence letter to the regional supervisor with some data on...

  13. Lake Andes NWR Water Use Report- 2005

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 2005. Short forms are supplied for the years water use report management plan. These forms cover...

  14. Lake Andes NWR Water Use Report- 1993

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1993. General water uses are discussed for 1993 for each unit, impoundment data is tabulated...

  15. Lake Andes NWR Water Use Report- 1971

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1971. General water uses are discussed for 1971 for each unit, impoundment data is tabulated...

  16. Lake Andes NWR Water Use Report- 1965

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1965. General water uses are discussed for 1965 for each unit, impoundment data is tabulated...

  17. Lake Andes NWR Water Use Report- 2010

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 2010. Short forms are supplied for the years water use report management plan. These forms cover...

  18. Lake Andes NWR Water Use Report- 2007

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 2007. Short forms are supplied for the years water use report management plan. These forms cover...

  19. Lake Andes NWR Water Use Report- 1990

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1990. General water uses are discussed for 1990 for each unit, impoundment data is tabulated...

  20. Lake Andes NWR Water Use Report- 1968

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1968. General water uses are discussed for 1968 for each unit, impoundment data is tabulated...

  1. Lake Andes NWR Water Use Report- 1970

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1970. General water uses are discussed for 1970 for each unit, impoundment data is tabulated...

  2. Lake Andes NWR Water Use Report- 1995

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1995. General water uses are discussed for 1995 for each unit, impoundment data is tabulated...

  3. Lake Andes NWR Water Use Report- 1960

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1960. A short summary of water rights is provided. Existing water supplies, as of January 1961,...

  4. Lake Andes NWR Water Use Report- 1969

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1969. General water uses are discussed for 1969 for each unit, impoundment data is tabulated...

  5. Lake Andes NWR Water Use Report- 1947

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1947. It provides a table of each unit along with the crest of spill elevation and a recommended...

  6. Lake Andes NWR Water Use Report- 1991

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1991. General water uses are discussed for 1991 for each unit, impoundment data is tabulated...

  7. Lake Andes NWR Water Use Report- 2012

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 2012. Short forms are supplied for the years water use report management plan. These forms cover...

  8. Lake Andes NWR Water Use Report- 1999

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1999. General water uses are discussed for 1999 for each unit, impoundment data is tabulated...

  9. Lake Andes NWR Water Use Report- 1994

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1994. General water uses are discussed for 1994 for each unit, impoundment data is tabulated...

  10. Lake Andes NWR Water Use Report- 1983

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1983. General water uses are discussed for 1983 for each unit, impoundment data is tabulated...

  11. Lake Andes NWR Water Use Report- 1987

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1987. General water uses are discussed for 1987 for each unit, impoundment data is tabulated...

  12. Lake Andes NWR Water Use Report- 2004

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 2004. Short forms are supplied for the years water use report management plan. These forms cover...

  13. Lake Andes NWR Water Use Report- 1992

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report contains locations and water use at Lake Andes NWR for 1992. General water uses are discussed for 1992 for each unit, impoundment data is tabulated...

  14. Issues of affinity: exploring population structure in the Middle and Regional Developments Periods of San Pedro de Atacama, Chile.

    Science.gov (United States)

    Torres-Rouff, Christina; Knudson, Kelly J; Hubbe, Mark

    2013-11-01

    The Middle Period (AD 400-1000) in northern Chile's Atacama oases is characterized by an increase in social complexity and regional interaction, much of which was organized around the power and impact of the Tiwanaku polity. Despite the strong cultural influence of Tiwanaku and numerous other groups evident in interactions with Atacameños, the role of immigration into the oases during this period is unclear. While archaeological and bioarchaeological research in the region has shown no evidence that clearly indicates large groups of foreign immigrants, the contemporary increase in interregional exchange networks connecting the oases to other parts of the Andes suggests residential mobility and the possibility that movement of people both into and out of the oases accompanied these foreign influences. Here, we analyze biodistance through cranial non-metric traits in a skeletal sample from prehistoric San Pedro de Atacama to elucidate the extent of foreign influence in the oases and discuss its implications. We analyzed 715 individuals from the Middle Period (AD 400-1000) and later Regional Developments Period (AD 1000-1450), and found greater phenotypic differences between Middle Period cemeteries than among cemeteries in the subsequent period. We argue that this greater diversity extends beyond the relationship between the oases and the renowned Tiwanaku polity and reflects the role of the oases and its different ayllus as a node and way station for the Middle Period's myriad interregional networks. PMID:24104607

  15. Cadenas operativas en la manufactura de arte rupestre: un estudio de caso en El Mauro, valle cordillerano del Norte Semiárido de Chile Rock Art Chaînes Opératoires: A Case Study From El Mauro, A Mountainous Valley In Semiarid Northern Chile

    Directory of Open Access Journals (Sweden)

    César A. Méndez Melgar

    2008-12-01

    Full Text Available Los contextos de producción son temas marginales en las discusiones relativas al arte rupestre. Independiente de los factores que hayan producido este sesgo en la comprensión del tema, se plantea que un examen a los procesos de manufactura es central para dar cuenta cabal del fenómeno rupestre. Se sugiere que el acto mismo de elaborar motivos es un acto comunicativo, tan cargado de contenidos sociales como podría pensarse que es la imagen misma, la cual ha recibido mayor atención en los estudios especializados. Se presenta un trabajo que expone una serie de procedimientos metodológicos destinados a entender la manufactura de petroglifos a través de sus instrumentos de trabajo y sus contextos de hallazgo. El área seleccionada fue El Mauro, valle cordillerano del Norte Semiárido, en donde se observa una profusión de estas manifestaciones para fechas del Holoceno tardío. Se discute una estrategia metodológica implementada a la luz de la noción que todo acto tecnológico es un acto social, se definen los instrumentos usados y se exponen una visión sintética del proceso a modo de una cadena operativa.Rock art production is a marginal issue in specialized discussions. Independently of the reasons for this bias in the current understanding of the subject, it is argued that an examination of production processes is crucial in order to fully account for the phenomenon. It is suggested that the elaboration of motifs is itself a communicative act, as loaded with social content as the images themselves, which have received more attention in specialized studies. This paper proposes a series of methodological procedures aimed at understanding rock art production through its production tools and recovery contexts. The study area comprises El Mauro mountain basin in semiarid northern Chile, where there is a high density of these manifestations from the late Holocene. A methodological strategy is discussed in light of the idea that every

  16. Asynchronous Glacial Chronologies in the Central Andes (15-40°S) and Paleoclimatic Implications

    Science.gov (United States)

    Zech, R.; Kull, C.; Kubik, P. W.; Veit, H.

    2006-12-01

    We have established glacial chronologies along a N-S transect over the Central Andes using 10Be surface exposure dating. Our results show that maximum glacial advances occurred asynchronously and reflect the varying influence and shifts of the major atmospheric circulation systems during the Late Quaternary: the tropical circulation in the north and the westerlies in the south. In Bolivia (three research areas in the Cordillera Real and the Cordillera Cochabamba, ~15°S) glacial advances could be dated to ~20 and 12 ka BP. This is in good agreement with published exposure age data from moraines in Bolivia and Peru (provided that all ages are calculated following the same scaling system). Accordingly, the maximum glaciation there probably occurred roughly synchronous to the temperature minimum of the global Last Glacial Maximum (LGM) and the lateglacial cold reversals. Strict correlation with neither the Younger Dryas in the northern hemisphere, nor the Antarctic Cold Reversal is possible due to the current systematic exposure age uncertainties (~10%). Glacier-Climate-Modelling corroborates the sensitivity of the reconstructed glaciers to temperature changes, rather than precipitation. On the contrary, there is good evidence for the dominant role of precipitation changes on the glacial chronologies in the lee of the Cordillera Occidental, i.e. on the Altiplano and further south. The pronounced lateglacial wet phase, which is well documented in lake transgression phases as far south as 28°S (-> tropical moisture source), seems to have caused glacial advances even at ~30°S. In two research areas in Chile at that latitude, we were able to date several lateglacial moraines. Besides, the maximum datable glaciation there occurred at ~30 ka BP. That is significantly earlier than the LGM (sensu strictu) and points to favourable climate conditions for glaciation at that time (particularly increased precipitation). We conclude that the westerlies were more intensive or

  17. Remote sensing and climate data as a key for understanding fasciolosis transmission in the Andes: review and update of an ongoing interdisciplinary project

    OpenAIRE

    Màrius V. Fuentes

    2006-01-01

    Fasciolosis caused by Fasciola hepatica in various South American countries located on the slopes of the Andes has been recognized as an important public health problem. However, the importance of this zoonotic hepatic parasite was neglected until the last decade. Countries such as Peru and Bolivia are considered to be hyperendemic areas for human and animal fasciolosis, and other countries such as Chile, Ecuador, Colombia and Venezuela are also affected. At the beginning of the 1990s a multi...

  18. Eso's Situation in Chile

    Science.gov (United States)

    1995-02-01

    ESO, the European Southern Observatory, in reply to questions raised by the international media, as well as an ongoing debate about the so-called "Paranal case" in Chilean newspapers, would like to make a number of related observations concerning its status and continued operation in that country [1]. THE ESO OBSERVATORY SITES IN CHILE The European Southern Observatory, an international organisation established and supported by eight European countries, has been operating more than 30 years in the Republic of Chile. Here ESO maintains one of the world's prime astronomical observatories on the La Silla mountain in the southern part of the Atacama desert. This location is in the Fourth Chilean Region, some 600 km north of Santiago de Chile. In order to protect the La Silla site against dust and light pollution from possible future mining industries, roads and settlements, ESO early acquired the territory around this site. It totals about 825 sq. km and has effectively contributed to the preservation of its continued, excellent "astronomical" quality. Each year, more than 500 astronomers from European countries, Chile and elsewhere profit from this when they come to La Silla to observe with one or more of the 15 telescopes now located there. In 1987, the ESO Council [2] decided to embark upon one of the most prestigious and technologically advanced projects ever conceived in astronomy, the Very Large Telescope (VLT). It will consist of four interconnected 8.2-metre telescopes and will become the largest optical telescope in the world when it is ready. It is safe to predict that many exciting discoveries will be made with this instrument, and it will undoubtedly play a very important role in our exploration of the distant universe and its many mysteries during the coming decades. THE VLT AND PARANAL In order to find the best site for the VLT, ESO performed a thorough investigation of many possible mountain tops, both near La Silla and in Northern Chile. They showed

  19. Observations of Comets and Eclipses in the Andes

    Science.gov (United States)

    Ziółkowski, Mariusz

    There is no doubt that the Incas possessed a system for observing and interpreting unusual astronomical phenomena, such as eclipses or comets. References to it, however, are scarce, often of anecdotal nature and are not collected into any coherent "Inca observation catalog". The best documented of such events is the "Ataw Wallpa's comet", seen in Cajamarca in July of 1533 and the solar eclipse, that in 1543, prevented conquistador Lucas Martínez from discovering the rich silver mines in northern Chile. Archived descriptions of the Andean population's reaction to these phenomena indicate that they were treated as extremely important omens, that should not, under any circumstances, be ignored.

  20. Tendencias generales en la toponimia del Norte Grande de Chile

    Directory of Open Access Journals (Sweden)

    Guillermo Latorre

    1997-09-01

    Full Text Available En este trabajo el autor se propone examinar las facetas más salientes de la preponderancia del sustrato indígena en la toponimia mayor del Norte Grande, asunto poco o nada tratado en descripciones del español de Chile. Pasa revista a voces como "Arica", "Chañaral", "Iquique", "Taltal", "Tocopilla", "Chuquicamata", "Andes", "Antofagasta", "Calama", "Pica", "Loa" y otras. Finalmente, da algunas explicaciones de esa marcada presencia de topónimos autóctonos a pesar de cinco siglos de dominio español. (In this paper, the author examines the most salient features of the prevalence of indigenous backgrounds in the toponymy of Northernmost Chile, an aspect barely tackled, or simply neglected, in the descriptions of Chilean Spanish. The author reviews terms such as "Arica", "Chañaral", "Iquique", "Taltal", "Tocopilla", "Chuquicamata", "Andes", "Antofagasta", "Calama", "Pica", "Loa", and others. Also, some explanations are offered that may justify the notorious presence of native placenames, in spite of five centuries of Spanish domination.

  1. The GalileoMobile starts its South American voyage - Astronomy education goes on tour through the Andes Mountains

    Science.gov (United States)

    2009-10-01

    and November 2009, and will cover 5000 kilometres. The voyage will largely take place across the Altiplano, or high plateau, shared by Peru, Bolivia and Chile, which is among the poorest regions in these countries. South America and the Andes Mountains were particularly chosen for the GalileoMobile Project for several reasons. IYA2009 already has a strong presence in the region through national contacts, including three Cornerstone IYA2009 projects: Developing Astronomy Globally, Universe Awareness and the Galileo Teacher Training Programme, which are all official partners of the project. Most people in Peru, Bolivia and Chile speak the same language, Spanish [1], and have a rich astronomical heritage dating back to the pre-Columbian Inca and Tiwanaku civilisations that lived on the Altiplano. The region's high elevation and the quality of its skies for astronomical observations also made it an attractive candidate for the maiden voyage of the GalileoMobile. The journey starts today 5 October 2009 in Antofagasta, Chile, with a free, public inauguration event at 19:00 in the Berta González Square at the Universidad Católica del Norte. The event, which will include observations of the night sky, is organised by ESO in collaboration with Explora II Region and the Astronomy Institute of the University. From Antofagasta the GalileoMobile heads north through La Paz in Bolivia and on into Peru. The return trip to Antofagasta goes via the Panamericana coastal road, and passes near the home of ESO's world-class observatory, the Very Large Telescope at Cerro Paranal. ESO Education and Outreach coordinator in Chile, Laura Ventura, will assist the GalileoMobile team as they greet communities throughout Chile's northern deserts. "The GalileoMobile is a wonderful initiative, and a unique opportunity to reinforce educational activities in the north of Chile and the neighbouring countries. It will promote greater awareness of astronomy and science", says Ventura. "We are looking

  2. Chile's energy

    Energy Technology Data Exchange (ETDEWEB)

    1988-11-18

    In recent years, a new emphasis has been placed on increasing solid fuel availability in Chile, to reach the northern mining operations where demand for power is soaring. The south of the country is well served by hydroelectric power plants (2.3 million kW). The coal industry has doubled its capacity to cope with increased copper production - the Tocopilla power plant at the Chuquicamata copper mine has been converted from oil to coal - and there has been a major investment programme in the steel industry. In 1986, 1.4 million tons of coal was mined, mostly from the Provinces of Concepcion and Arauco, the remainder from Valdivia. Since then, 70 million US dollars has been invested by COCAR SA in the Pecket deposit near Punta Arenas. Coal from Pecket should cost around 26 dollars/t compared with 60 dollars/t for underground coal. It should support an expanded coal market in Chile and may also be able to compete in the Brazilian and Argentine markets. Reserves are estimated at over 200 Mt. Petroleum reserves in Tierra del Fuego are nearly exhausted; seismic surveys in the Atacama desert are promising.

  3. Fishery Management Plan for Lake Andes National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Lake Andes was a much larger body of water prior to the construction of an artificial outlet structure that lowered the water level by 13 feet. Since Lake Andes is...

  4. Recreational Fishery Management Plan for Lake Andes National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Current condition of lake Andes (1996) and highlights potential problems and recommendations for improving the lake as a hatchery. Lake Andes was a much larger body...

  5. Fish Population Investigation: Lake Andes, Charles Mix County

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Brief background on Lake Andes fishing history, and data on current fish populations. Lake Andes was a much larger body of water prior to the construction of an...

  6. On recent measurements from the Andes Lidar Observatory

    Science.gov (United States)

    Liu, Alan Z.; Snively, Jonathan; Heale, Christopher; Cao, Bing

    2016-07-01

    The Andes Lidar Observatory is an upper atmosphere observatory located in Cerro Pachón, Chile (30.3S, 70.7W). It houses a Na Wind/Temperature Lidar, an all sky airglow imager, a mesospheric temperature mapper, an infrared imager and a meteor radar. This suite of instrumentation provides comprehensive measurements of the mesopause region and enables detailed study of wave dynamics. With the recent upgrade of the Na lidar, many complex dynamic processes were observed and resolved in detail. I will present several intriguing phenomena seen in the lidar measurement from recent campaigns, and a detailed analysis of a complex wave propagation event, which involved a large vertical wind oscillation exceeding 10 m/s. A nonlinear gravity wave model was able to reproduce most of the observed features. The results suggest that the wave experienced partial reflections at two altitudes and a critical layer in between, resulting in large vertical wind amplitude and multi-layer distribution of wave energy.

  7. Fundacion Chile Incubator : Chile Case Study

    OpenAIRE

    World Bank

    2014-01-01

    Foundation Chile was created in 1976 as a nonprofit governed jointly by the Chilean government and a large American conglomerate. It proactively introduces technology innovations and develops companies in target industries including agribusiness, marine resources, forestry, environment and chemical metrology, human capital, and information and communication technologies. Among its successe...

  8. Evaluación de metales redox-sensitivos como proxies de paleoxigenación en un ambiente marino hipóxico del norte de Chile Redox-sensitive metals evaluation as proxis of paleoxygenation in a hypoxic marine environment of northern Chile

    Directory of Open Access Journals (Sweden)

    JORGE VALDÉS

    2004-03-01

    metales registrada entre las muestras de la parte superior de los testigos (correspondientes a antes de 1996 y las muestras superficiales (correspondientes al año 2000 y tomadas en la misma zona de los testigos, pueden ser atribuidas al efecto de El Niño 1997-1998, el cual provocó un brusco descenso en el flujo de metales (principalmente Ni y Cd hacia los sedimentos, debido a una condición más oxigenada de la columna de agua. Este trabajo muestra que de los cinco metales analizados, solo en Ni y el Cd parecen tener un potencial como indicadores de paleoxigenación en la bahía Mejillones. Sin embargo, su uso está restringido para identificar cambios extremos desde una condición anóxica a una óxica en los sedimentos de fondo de esta bahía.The distribution of molybdenum, cadmium, zinc, vanadium and nickel, all redox-sensitive metals, was analyzed under a spatial (surface sediment samples and temporal (core samples perspective, in order to identify the potential of these metals for paleoxygenation interpretations in Mejillones bay, a hypoxic environment of northern Chile. Lithogenic supply (according to aluminum was discarded. Biogenic flux is not the unique factor that controls the mechanism of metals preservation in sediments of this bay. Spatial variation of metals concentration was investigated in relation to the bottom water oxygenation in each sampling station. Results showed that only Ni and Cd present a strong correlation with dissolved oxygen, increasing their concentration toward the deepest area of the bay were an oxygen minimum zone prevails with values around 0.02 mL L-1. The temporal variation in redox-sensitive metals, recorded in three sediments core covering the last 2,000 years, showed that bottom oxygenation of the bay changed from a more oxygenated environment in the past to a less oxygenated environment at present. A biogenic flux across a very well developed oxycline, associated to an anoxic sediment-water interface, are proposed to be the

  9. Plasticity in feeding selectivity and trophic structure of kelp forest associated fishes from northern Chile Plasticidad en la selección de alimento y estructura trófica de los peces asociados a bosques de macroalgas pardas del norte de Chile

    Directory of Open Access Journals (Sweden)

    ALEJANDRO PÉREZ-MATUS

    2012-03-01

    Full Text Available One of the primary ways in which species interact with their environment is through foraging; thereby directly consuming some fraction of their surrounding habitat. The habitat itself, in turn, may dictate the types of foraging opportunities that are available to the inhabitants. To investigate the relationship between habitat availability and diet composition of habitat-associated fishes, we estimated the relative abundance of the potential sessile and mobile prey items and the diet of the fish species assemblage associated to kelp forest. Specifically, diet and feeding selectivity of the kelp-forest associated fish assemblage were determined by calculating Manly's alpha selectivity index. We determined the diet of kelp forest associated fishes and their foraging behavior by comparing prey availability with those items present in the stomachs of fishes captured by gill net and spear gun. We calculated the degree of dietary overlap among fishes from four locations along the northern coast of Chile. Results indicate that utilization of prey by predators is predominantly affected by potential prey availability. With the exception of the two carnivorous species such as Pinguipes chilensis (Valenciennes, 1883 and Paralabrax humeralis (Cuvier & Valenciennes, 1828, whose diet did not change among sites, all other kelp-associated fishes changed their dietary habitats to consistent with the availability of local resources. Benthic resources changed among the different study sites, which led to differing diets even in the same species from different locations. Eleven of the 12 kelp forest fishes also showed some selectively for benthic prey. We conclude that the ability of fishes to be plastic in their feeding preference and, therefore, partition the benthic resources may set adaptations to co-exist in a dynamic environment such as kelp forest.Una de las principales formas en que las especies interactúan con su medio ambiente es a través de la

  10. The complete mitochondrial genome of the endemic and threatened killifish Orestias ascotanensis Parenti, 1984 (Cyprinodontiformes, Cyprinodontidae) from the High Andes.

    Science.gov (United States)

    Quezada-Romegialli, Claudio; Guerrero, Claudia Jimena; Véliz, David; Vila, Irma

    2016-07-01

    The killifish Orestias ascotanensis is endemic to the small isolated springs of Ascotán salt pan in the Central High Andes, Chile. Due to small populations, mining activity, and increasing aridity, this species is catalogued in danger of extinction. The complete mitochondrial genome of O. ascotanesis was assembled with an Ion Torrent sequencer (chip 318) that produced 2.61 million of reads. The 16 617 bp of the entire genome consisted of 22 transfer RNAs, 2 ribosomal RNAs, 13 protein-coding genes, and a control region, showing that the gene composition and arrangement match to that reported for most fishes. PMID:26152352

  11. Initiation of the Magallanes foreland basin: Timing of the southernmost Patagonian Andes orogeny revised by detrital zircon provenance analysis

    Science.gov (United States)

    Fildani, A.; Cope, T.D.; Graham, S.A.; Wooden, J.L.

    2003-01-01

    New sensitive high-resolution ion microprobe-reverse geometry U-Pb detrital zircon data establish the timing of onset of foreland basin subsidence in the Magallanes basin and the age of the Patagonian Andes in southernmost Chile. Initiation of the Magallanes foreland basin is signaled by the abrupt occurrence of sandstone of the Punta Barrosa Formation, loosely dated as upper Albian-Cenomanian from biofacies assemblages. Detrital zircon analyses demonstrate that the Punta Barrosa Formation is not older than 92 ?? 1 Ma and that the linked Andean belt started forming in the Turonian.

  12. Relación de aguas superficiales y subterráneas en el área del lago Chungará y lagunas de Cotacotani, norte de Chile: un estudio isotópico Relation of surface and underground waters in Chungará and Cotacotani lake districts, northern Chile: an isotopic study

    Directory of Open Access Journals (Sweden)

    Christian Herrera

    2006-07-01

    Full Text Available El lago Chungará y las lagunas de Cotacotani corresponden a cuerpos de aguas superficiales localizados al noroeste de la Cuenca del Lauca, en el Altiplano del norte de Chile. Todas las aguas superficiales y subterráneas tienen una salinidad baja a moderada con conductividades eléctricas variables entre 48,7 y 3090 μS/cm. Los lagos están conectados a acuíferos situados en los flancos de los edificios volcánicos próximos, así como en los depósitos de brechas de avalancha del volcán Parinacota. Las composiciones isotópicas de δ18O y δD y su relación con las concentraciones de cloruro de las aguas del lago Chungará, lagunas de Cotacotani, manantiales afluentes y del río Chungará, demuestran que: a. las aguas del lago Chungará presentan una composición química e isotópica homogénea tanto en la horizontal como en la vertical, lo que indica una buena mezcla de las aguas en el lago; b. una parte importante de la recarga hídrica que alimenta las lagunas de Cotacotani procede de aguas del lago Chungará, canalizada a través de un flujo lateral subterráneo y c. el agua subterránea que da origen a los manantiales de la zona tiene su recarga principal en las precipitaciones que se registran durante los meses de primavera-verano (octubre-marzo. Los altos contenidos de tritio (³H medidos en las aguas de los manantiales del sector indican que existe una recarga actual (durante los últimos decenios al sistema acuífero. La aplicación de modelos de parámetro agregado para la interpretación del tiempo de residencia del agua en el acuífero indica que el modelo de flujo de pistón es el que mejor se ajusta a las características isotópicas de estas aguas subterráneasLake Chungará and Cotacotani lake districts are surface water bodies located to the northwest of Lauca Basin in the northern Chilean Altiplano. Surface and underground waters show low to moderate saline content and an electrical conductivity in the range of 48.7 to

  13. Geodetic observations of megathrust earthquakes and backarc wedge deformation across the central Andes

    Science.gov (United States)

    Weiss, J. R.; Brooks, B. A.; Foster, J. H.; Bevis, M. G.; Echalar, A.; Caccamise, D.; Heck, J. M.

    2014-12-01

    High-precision Global Positioning System (GPS) data offer an opportunity to investigate active orogenic wedges yet surface velocity fields are available for only a few examples worldwide. More observations are needed to link deformation processes across multiple timescales and to better understand strain accumulation and release in active wedge settings. Here we present a new GPS velocity field for the central Andes and the backarc orogenic wedge comprising the southern Subandes of Bolivia (SSA), a region previously thought to be mostly isolated from the plate boundary earthquake cycle. The time span of our observations (2000 to mid-2014) includes two megathrust earthquakes along the Chile trench that affected the SSA. The 2007 Mw 7.7 Tocopilla, Chile earthquake resulted in a regional postseismic decrease in the eastward component of horizontal surface velocities. Preliminary analysis of the deformation field from the April 01 2014 Mw 8.2 Pisagua, Chile earthquake also indicates a postseismic signal extending into the SSA. We create an interseismic velocity field for the SSA by correcting campaign GPS site velocities for the seasonal cycles estimated from continuous GPS site time series. We remove the effects of both megathrust events by estimating coseismic steps and fitting linear and logarithmic functions to the postseismic GPS site motions. The velocity estimates at most locations increase after correcting for the transients. This finding suggests that forces leading to shortening and earthquakes in the backarc wedge are not as temporally consistent as previously considered.

  14. Genetics of colonization in Hypochaeris tenuifolia (Asteraceae, Lactuceae) on Volcán Lonquimay, Chile.

    Science.gov (United States)

    Tremetsberger, K; Stuessy, T F; Samuel, R M; Baeza, C M; Fay, M F

    2003-10-01

    Understanding the genetics of colonizing populations has been, and continues to remain, an important focus in evolutionary biology. Different theoretical models predict varying levels of genetic variation in colonizing populations depending upon strength of founder effect, gene flow and rate of population growth and immigration following colonization. We analyse overall genetic variation using amplified fragment length polymorphism markers in colonizing populations of Hypochaeris tenuifolia (Asteraceae) in the southern Andes. Volcán Lonquimay newly erupted on 25 December 1988, producing a side cone, La Navidad, and sent lava and ash into surrounding areas. Many domesticated animals (estimated at 10 000) and many natural plant populations were destroyed. Into this new open habitat have come immigrant populations of several angiosperm species, most conspicuously H. tenuifolia that forms leaf rosettes with flowering scapes to 15 cm and orange-yellow heads 1-2 cm in diameter. Genetic diversity in five founder populations in the eruption zone is compared with that from five nearby survivor populations, as well as with eight isolated northern and four southern populations from throughout the entire range of the species in Chile. Results from 477 individuals representing 447 different multilocus phenotypes, yielded 170 DNA fragments of which 144 (85%) were polymorphic. Genetic diversity within founder populations is neither lower than in survivor populations nor in isolated populations throughout the range of the species, but it is lower among founder populations than among other populations immediately and distantly outside the zone of disturbance. Closest genetic similarity occurs between founders and nearby survivor populations as well as those in adjacent southern regions. PMID:12969468

  15. Copper Bioleaching in Chile

    OpenAIRE

    Juan Carlos Gentina; Fernando Acevedo

    2016-01-01

    Chile has a great tradition of producing and exporting copper. Over the last several decades, it has become the first producer on an international level. Its copper reserves are also the most important on the planet. However, after years of mineral exploitation, the ease of extracting copper oxides and ore copper content has diminished. To keep the production level high, the introduction of new technologies has become necessary. One that has been successful is bioleaching. Chile had the first...

  16. Marine Energy in Chile

    OpenAIRE

    Antonio Levy

    2012-01-01

    This is the first issue of a new series dedicated to deliver concise information on energy innovation published by the Energy Innovation Center at the IDB. This issue offers a primer on the potential for marine energy in Chile. The ocean is increasingly recognized as a viable source of renewable energy, and Chile, with its long coastline, powerful waves and tidal currents, has captured the attention of marine energy proponents. While harvesting this source of energy would increase sustainabil...

  17. Geodynamics of the northern Andes: Subductions and intracontinental deformation (Colombia)

    Science.gov (United States)

    Taboada, Alfredo; Rivera, Luis A.; Fuenzalida, AndréS.; Cisternas, Armando; Philip, Hervé; Bijwaard, Harmen; Olaya, José; Rivera, Clara

    2000-10-01

    New regional seismological data acquired in Colombia during 1993 to 1996 and tectonic field data from the Eastern Cordillera (EC) permit a reexamination of the complex geodynamics of northwestern South America. The effect of the accretion of the Baudó-Panama oceanic arc, which began 12 Myr ago, is highlighted in connection with mountain building in the EC. The Istmina and Ibagué faults in the south and the Santa Marta-Bucaramanga fault to the northeast limit an E-SE moving continental wedge. Progressive indentation of the wedge is absorbed along reverse faults located in the foothills of the Cordilleras (northward of 5°N) and transpressive deformation in the Santander Massif. Crustal seismicity in Colombia is accurately correlated with active faults showing neotectonic morphological evidences. Intermediate seismicity allows to identify a N-NE trending subduction segment beneath the EC, which plunges toward the E-SE. This subduction is interpreted as a remnant of the paleo-Caribbean plateau (PCP) as suggested by geological and tomographic profiles. The PCP shows a low-angle subduction northward of 5.2°N and is limited southward by a major E-W transpressive shear zone. Normal oceanic subduction of the Nazca plate (NP) ends abruptly at the southern limit of the Baudó Range. Northward, the NP subducts beneath the Chocó block, overlapping the southern part of the PCP. Cenozoic shortening in the EC estimated from a balanced section is ˜120 km. Stress analysis of fault slip data in the EC (northward of 4°N), indicates an ˜E-SE orientation of σ1 in agreement with the PCP subduction direction. Northward, near Bucaramanga, two stress solutions were observed: (1) a late Andean N80°E compression and (2) an early Andean NW-SE compression.

  18. Seismic hazard assessment in the Northern Andes (PILOTO Project

    Directory of Open Access Journals (Sweden)

    G. Grünthal

    1999-06-01

    Full Text Available Five Andean countries (Bolivia, Peru, Ecuador, Colombia, Venezuela and four European countries (Italy, Spain, Holland, Germany cooperated in the PILOTO program ("Test area for earthquake monitoring and seismic hazard assessment", launched under GSHAP and sponsored by the European Union (Ct.94-0103 to produce a unified SHA for the Andean region. Activities included the integration of national earthquake catalogues and source zonings in common regional databases and joint technical workshops for the assessment of the regional hazard, expressed in terms of expected peak ground acceleration with 10% exceedance probability in 50 years.

  19. Seismic hazard assessment in the Northern Andes (PILOTO Project)

    OpenAIRE

    G. Grünthal; Rendon, H.; Ocola, L.; Drake, L.; H. Yepez; C. Dimaté; Giardini, D.

    1999-01-01

    Five Andean countries (Bolivia, Peru, Ecuador, Colombia, Venezuela) and four European countries (Italy, Spain, Holland, Germany) cooperated in the PILOTO program ("Test area for earthquake monitoring and seismic hazard assessment"), launched under GSHAP and sponsored by the European Union (Ct.94-0103) to produce a unified SHA for the Andean region. Activities included the integration of national earthquake catalogues and source zonings in common regional databases and joint technical workshop...

  20. Relationship between the genetic structure of the Andean toad Rhinella spinulosa (Anura: Bufonidae) and the northern Chile landscape (21°- 24° S) Relación entre la estructura genética del sapo andino Rhinella spinulosa (Anura: Bufonidae) y el paisaje del norte de Chile (21°- 24° S)

    OpenAIRE

    CAROLINA E GALLARDO; HÉCTOR J HERNÁNDEZ; Diniz-Filho, José A. F.; R. EDUARDO PALMA; MARCO A MÉNDEZ

    2011-01-01

    We analyzed the relationship of landscape and environmental features on the genetic differentiation of Rhinella spinulosa (Wiegmann, 1834) in the Altiplano of Antofagasta (Chile). We performed three types of analyses at different spatial scales: (1) Considering all populations; (2) Grouping populations by watershed and by sub-watershed; and (3) Using the results of a spatial analysis of molecular variation (SAMOVA). Landscape features were incorporated using Geographic Information Systems, wi...

  1. Contenido de metales en Cancer polyodon (Crustacea: Decapoda) en un sistema de bahías del norte de Chile (27°S) Metal contents in Cancer polyodon (Crustacea: Decapoda) in a bay system of northern Chile (27°S)

    OpenAIRE

    Alexis Castillo; Jorge Valdés

    2011-01-01

    El contenido de Zn, Cu, Cd, Pb, Fe, Al y Ni fue analizado en tejido muscular de Cancer polyodon en las bahías de Caldera, Calderilla, Inglesa y Salada (Atacama, Chile). Los resultados fueron comparados con estudios similares desarrollados por otros autores y la normativa de carácter nacional e internacional relacionada con el contenido de metales pesados en crustáceos para consumo humano. El orden de abundancia de los metales analizados en C. polyodon fue Cd

  2. Diversity of the genus Polylepis (Rosaceae, Sanguisorbeae in the Peruvian Andes

    Directory of Open Access Journals (Sweden)

    Wilfredo Mendoza

    2011-08-01

    Full Text Available This study provides information on the diversity of Peruvian species of Polylepis. Nineteen (19 species are reported here (more than 70% of the 27 species registered for the whole Andean region. As a result, Peru could be considered as the country with the largest diversity of Polylepis species, in comparison with Bolivia (13, Ecuador (7, Argentina (4, Colombia (3, Chile (2, and Venezuela (1. The species occur in 19 departments of Peru, with the majority of them in Cusco (10 and Ayacucho (8. Species diversity is mostly concentrated in the Peruvian southern Andes (15 species, with the region becoming the potential center of diversification of the genus Polylepis. Regarding their altitudinal distribution, the greatest diversity (18 is found between 3000 and 4000 m.

  3. Horizontal subduction zones, convergence velocity and the building of the Andes

    CERN Document Server

    Martinod, Joseph; Roperch, Pierrick; Guillaume, Benjamin; Espurt, Nicolas; 10.1016/j.epsl.2010.09.010

    2010-01-01

    We discuss the relationships between Andean shortening, plate velocities at the trench, and slab geometry beneath South America. Although some correlation exists between the convergence velocity and the westward motion of South America on the one hand, and the shortening of the continental plate on the other hand, plate kinematics neither gives a satisfactory explanation to the Andean segmentation in general, nor explains the development of the Bolivian orocline in Paleogene times. We discuss the Cenozoic history of horizontal slab segments below South America, arguing that they result from the subduction of oceanic plateaus whose effect is to switch the buoyancy of the young subducting plate to positive. We argue that the existence of horizontal slab segments, below the Central Andes during Eocene-Oligocene times, and below Peru and North-Central Chile since Pliocene, resulted (1) in the shortening of the continental plate interiors at a large distance from the trench, (2) in stronger interplate coupling and...

  4. Pre-collisional extensional tectonics in convergent continental margins: the cretaceous evolution of the central cordillera of the Colombian Andes

    OpenAIRE

    Zapata Henao, Sebastian

    2015-01-01

    Abstract: The Cretaceous tectonic evolution of the Northern Andes continental margin is characterized by continuous convergence that allowed the formation of continental volcanic arcs, back arc basins, extensional divergent tectonics and accretion of exotic terranes. Such a record, particularly the extensional phases, is commonly hidden by the overimposition of deformational events associated with evolution of the subduction configuration, collision of exotic terranes and strike slip fragment...

  5. Mama Cotacachi: History, local perceptions, and social impacts of climate change and glacier retreat in the Ecuadorian Andes

    OpenAIRE

    Rhoades, Robert E.; Zapata Ríos, X.; Aragundy Ochoa, J.

    2007-01-01

    Through the lens of the complete loss of the glacier on Mount Cotacachi in northern Ecuador, this book chapter explores the human and environment interface between the impacts of global warming and the people living in the Andes Mountains. Using a transdisciplinary approach, the researchers analyze photographic records and sketches back to the late eighteen hundreds, oral histories of the local people, and scientific monitoring of changes in water level in local lakes and rivers. The response...

  6. [Domestic violence in Chile].

    Science.gov (United States)

    León, Tomás; Grez, Marcela; Prato, Juan Andrés; Torres, Rafael; Ruiz, Sergio

    2014-08-01

    According to recent surveys, there is a high prevalence of domestic violence (DV) in Chile. A systematic review was conducted in PubMed, Scielo, and Lilacs with the MesH terms "Chile", "Mental Health", "Health", "Domestic Violence", to explore the impact of DV on health in Chile. Eleven studies fulfilled the inclusion criteria. Two studies were prospective, exploring the influence of DV on maternal-infant health. Nine studies explored the influence of DV on mental health in adults. DV was associated with deranged mental health indicators specially anxiety and depressive symptoms and suicidal ideation. Similar results were observed among mothers who were victims of violence and their children. It is concluded that DV is a complex phenomenon with serious effects on health. However the number of studies on the subject is low and new follow up studies are required. Predictive models for DV and effective preventive measures are urgently needed. PMID:25424674

  7. Copper Bioleaching in Chile

    Directory of Open Access Journals (Sweden)

    Juan Carlos Gentina

    2016-03-01

    Full Text Available Chile has a great tradition of producing and exporting copper. Over the last several decades, it has become the first producer on an international level. Its copper reserves are also the most important on the planet. However, after years of mineral exploitation, the ease of extracting copper oxides and ore copper content has diminished. To keep the production level high, the introduction of new technologies has become necessary. One that has been successful is bioleaching. Chile had the first commercial operation in the world exclusively via bioleaching copper sulfides. Nowadays, all bioleaching operations run in the country contribute to an estimated 10% of total copper production. This article presents antecedents that have contributed to the development of copper bioleaching in Chile.

  8. Changes in tree species richness, stand structure and soil properties in a successional chronosequence in northern Chiloé Island, Chile Cambios en la riqueza de especies arbóreas, estructura de rodales y propiedades del suelo en una cronosecuencia sucesional en el norte de la Isla de Chiloé, Chile

    Directory of Open Access Journals (Sweden)

    JUAN C. ARAVENA

    2002-06-01

    Full Text Available We studied a chronosequence of forest fragments in northern Chiloé Island, southern Chile, with the aim of assessing ecosystem recovery patterns following anthropogenic disturbance. Hypotheses regarding successional trends in tree species richness, the replacement of shade-intolerant by shade-tolerant species, and the impact of disturbance on soil properties were evaluated in nine forest stands. The chronosequence encompassed two early (minimum stand age Estudiamos una cronosecuencia de bosques sucesionales en el norte de la Isla de Chiloé, con el objeto de determinar sus patrones de recuperación luego de perturbación antrópica. Se evaluaron hipótesis referentes a las tendencias de cambio en la riqueza de especies arbóreas a lo largo de la sucesión, el reemplazo de especies sombra intolerantes por especies sombra tolerantes, y el impacto de la perturbación en las propiedades edáficas de estos fragmentos. Muestreamos nueve rodales, representados por dos bosques sucesionales tempranos (<15 años de edad mínima del rodal, tres rodales intermedios (30-60 años, tres avanzados (129-134 años, y un bosque antiguo (ca. 200 años. Las edades mínimas fueron estimadas a través de muestras de incremento radial de al menos 30 árboles del dosel por rodal. Los rodales tempranos e intermedios mostraron evidencias de perturbación por incendios moderados, con unos pocos grandes árboles vivos remanentes. En cada rodal se establecieron parcelas permanentes de 50 x 20 m para determinar densidades y áreas basales de árboles, con subparcelas interiores para estimar densidades de brinzales y plántulas. Para caracterizar los procesos edáficos en los rodales se determinó el pH del suelo, los contenidos totales de carbono (C y nitrógeno (N, N disponible y densidad aparente. En contraste con la hipótesis que predice una disminución de la riqueza de especies arbóreas en rodales más antiguos, debido a la exclusión de especies pioneras, la riqueza

  9. The Ordovician Quebrada Grande Formation, Cordón de Lila (Antofagasta Region, northern Chile: stratigraphicand paleogeographic significance La Formación QuebradaGrande, del Ordovícico, Cordón de Lila (Región de Antofagasta, norte de Chile: significado estratigráfico y paleogeográfico

    Directory of Open Access Journals (Sweden)

    Javier González

    2007-07-01

    Full Text Available The Cordón de Lila is located immediately to the south of the Salar de Atacama, in northern Chile. The geology of the Cordón de Lila is characterized by extensive outcrops of Early Paleozoic volcanic and sedimentary rocks (Cordón de Lila Igneous and Sedimentary Complex; CISL that form the 'Arco magmático occidental' (AMO which is intruded by a multiple suite of Middle Ordovician to Lower Silurian granitoids. In this contribution we report the results of a sedimentological and paleontological study of a recently discovered 1,600 m thick marine Ordovician sedimentary sequence (Quebrada Grande Formation which unconformably overlies the CISL. The Quebrada Grande Formation comprises three mayor facies associations. In stratigrafic order, these facies associations are: matrix-supported conglomerates (1, interbedded sandstones and siltstones (2 and clast-supported conglomerates (3. Facies association (1 is interpreted as debris flow deposits accumulated in a proximal marine fan-delta setting while the overlying sandstones and siltstones facies (2 represent open-marine platform deposits. Clast-supported conglomerates (3 are the record of high-energy sedimentary episodes during which coarse sediments reached the distal part of the fan-delta. The detrital fraction of the Quebrada Grande Formation is derived from the erosion of the Cambrian?-Lower Ordovician? CISL volcanic arc, the plutonio roots of the arc and its continental basement. The age of this formation is well constrained by the occurrence of brachiopods (Paralenorthis sp., Monorthis transversa Benedetto, and Mollesella? sp. near the base and graptolites (Tetragraptus sp. and Cryptograptus? sp. towards the middle of the succession. Both brachiopods and graptolites indicate an Arenigian to early Llanvirnian (Darriwilian age. The brachiopod assemblage from Cordón de Lila displays affinities with the Famatina basin fauna of western Argentina. The absence of taxa in common between the AMO and

  10. Strike-slip faults in the southernmost Andes and the development of the Patagonian orocline

    Science.gov (United States)

    Cunningham, W. Dickson

    1993-02-01

    The Patagonian orocline is the 90° bend in the southernmost Andes between 50°S and 56°S. Paleomagnetic and structural data indicate that the orocline is, at least in part, the product of tectonic rotation. Recent field work in the Beagle Channel region of southernmost Chile provides evidence for widespread left-lateral strike-slip faulting in the internal zones of the mountain belt. Both arms of the Beagle Channel are interpreted to be left-lateral strike-slip faults based on detailed study of mesoscale strike-slip faults (Riedel shears) observed in coastal outcrops. Although much of the evidence indicates Cenozoic brittle strike-slip faulting, other fabric data, including vertical foliation zones containing horizontal quartz stretching lineations and ductile left-lateral kinematic indicators, suggest that Mesozoic ductile strike-slip or oblique-slip shearing also occurred. The implication is that the mid-Cretaceous Andean orogeny involved the transpressional inversion of the Rocas Verdes marginal basin and that transpression has been the dominant deformational regime in the region for the last 120 Ma. Regional left-lateral strike-slip faults are now recognized in all lithotectonic provinces of the southernmost Andes. A statistical study of regional lineament trends using aerial photographs and satellite imagery suggests that many unstudied lineaments are also strike-slip faults. A new model is proposed that integrates the development of strike-slip faulting and the structural evolution and uplift of the southernmost Andes with the rotational development of the orocline. The Patagonian orocline appears to be the product of broad interplate shearing accommodated by strike-slip faulting, block rotation, and contraction and is probably continuing to evolve today.

  11. Un nuevo espécimen de cocodrilo marino del Jurásico Medio del norte de Chile: revalidación de metriorhynchus westermanni (crocodyliformes: metriorhynchidae) = A new specimen of marine crocodile from the Middle Jurassic of northern Chile : revalidation of metriorhynchus westermanni (Crocodyliformes: metriorhynchidae)

    OpenAIRE

    Zulma Gasparini; Ariana Paulina-Carabajal; Guillermo Chong

    2013-01-01

    Se revalida la especie Metriorhynchus -westermanni Gasparini a partir de un nuevo espécimen de cocodrilo marino caloviano (Metriohrynchidae) hallado en el curso medio de quebrada Cherejara, Sierra del Medio, Región de Antofagasta, Chile. El análisis del neurocráneo y de los huesos asociados demuestra que el holotipo de M. westermanni no es unjuvenil deMetriohrynchus casamiquelai Gasparini y Chong, como anteriormente se propuso. Varias diferencias morfológicas tales como frontal y parietal en ...

  12. Evaluación de metales redox-sensitivos como proxies de paleoxigenación en un ambiente marino hipóxico del norte de Chile Redox-sensitive metals evaluation as proxis of paleoxygenation in a hypoxic marine environment of northern Chile

    OpenAIRE

    JORGE VALDÉS

    2004-01-01

    Se analizó la distribución de molibdeno, cadmio, zinc, vanadio y níquel, todos metales redox-sensitivos, bajo una perspectiva espacial (sedimento superficial) y temporal (testigos de sedimento), con el propósito de determinar su potencial como indicadores de paleoxigenación en la bahía Mejillones del Sur, un ambiente hipóxico del norte de Chile. El aporte litogénico (de acuerdo a aluminio) fue descartado. Además, el flujo biogénico no es el único factor que controla la preservación de metales...

  13. Concentración de metales pesados (Cu, Ni, Zn, Cd, Pb) en la biota y sedimentos de una playa artificial, en la bahía San Jorge 23°S, norte de Chile Heavy metals concentration (Cu, Ni, Zn, Cd, Pb), in biota and sediments of an artificial beach, in San Jorge bay 23°S, northern Chile

    OpenAIRE

    Gabriel Castro; Jorge Valdés

    2012-01-01

    Se evaluó el contenido de metales pesados (Cu, Ni, Zn, Cd, Pb) en la biota y el sedimento de una playa artificial (Paraíso) y una playa natural (El Lenguado), ubicadas en la bahía San Jorge, norte de Chile. Los resultados fueron utilizados para comparar ambos sistemas, el grado de cumplimiento de la normativa ambiental nacional e internacional, y el efecto de la construcción de la playa artificial sobre el nivel de contaminación por metales existentes históricamente en esa zona. En cada playa...

  14. Estructura térmica superficial del mar asociada a la distribución espacio-temporal de sardina y anchoveta en la zona norte de Chile entre 1987 y 1992 Sea surface thermal structure associated to the space-temporal distribution of sardine and anchovy in northern Chile

    OpenAIRE

    Eleuterio Yáñez R; Antonio González C; María Angela Barbieri B

    1995-01-01

    Utilizando un sistema de información geográfica (SIG), se analizan los cambios de la estructura térmica superficial del mar asociados a las variaciones espaciales y mensuales de sardina (Sardinops sagax) y anchoveta (Engraulis ringens), en la zona norte de Chile (18°21'-24°00'S) entre 1987 y 1992. Para tal efecto se toma en cuenta el índice de abundancia CPUE, estimado para ambas especies a partir de la información de una flota cerquera industrial. y datos de temperatura superficial del mar (...

  15. Phytogeography of the vascular páramo flora of Ramal de Guaramacal (Andes, Venezuela) and its ties to other páramo floras

    OpenAIRE

    Cuello, Nidia L.; Cleef, Antoine M.; Aymard, Gerardo

    2010-01-01

    Ramal de Guaramacal is an outlier and lower elevation mountain range located at the northeastern end of the Venezuelan Andes. Phytogeographical patterns and affinities of the low altitude and wet vascular páramo flora of Ramal de Guaramacal, have been studied with emphasis in to the analysis of the floristic connections of the Guaramacal páramo flora with the neighboring dry páramos of the Sierra Nevada de Mérida and other páramo floras of the northern Andes and Central America. A total of 25...

  16. Biología poblacional de huirales submareales de Macrocystis integrifolia y Lessonia trabeculata (Laminariales, Phaeophyceae en un ecosistema de surgencia del norte de Chile: variabilidad interanual y El Niño 1997-1998 Population biology of the subtidal kelps Macrocystis integrifolia and Lessonia trabeculata (Laminariales, Phaeophyceae in an upwelling ecosystem of northern Chile: interannual variability and El Niño 1997-1998

    Directory of Open Access Journals (Sweden)

    J.M. ALONSO VEGA

    2005-03-01

    Full Text Available This paper describes the population biology of Lessonia trabeculata and Macrocystis integrifolia during and after the 1997-1998 El Niño in an area of permanent coastal upwelling in northern Chile. Spatial and temporal patterns of distribution were evaluated seasonally for adult and juvenile sporophytes of both species between 1996 and 2003. These two kelp form an assemblage distributed between 2 and 15 m depth, with disjunct patterns along a bathymetric gradient, including two morphs of L. trabeculata, the occurrence of which depends on the presence or absence of M. integrifolia. During the 1997-1998 El Niño the spatial-temporal patterns of abundance of the kelp assemblage were maintained by the continuity of coastal upwelling, which buffered and moderated superficial warming of the sea and depletion of nutrients. In this context, localities associated with coastal upwelling areas could function as "sources" of reproductive propagules after passage of El Niño, thus increasing kelp recolonization rates in "sink" localities, which suffered local kelp extinctions. Intensification of upwelling processes after the 1998-2000 La Niña increased nutrient inputs into subtidal habitats, favoring the productivity of the kelp assemblage. However, an abrupt change in the spatial-temporal patterns of abundance of the black sea urchin Tetrapygus niger, the most conspicuous benthic grazer in northern Chile, produced local extinctions of M. integrifolia and compression of the range of bathymetric distribution of L. trabeculata. Top-down (mortality of benthic carnivores during the 1997-1998 El Niño and bottom-up effects (intensity and frequency of upwelling in this subtidal coastal ecosystem appear to regulate the kelp-herbivore interactions in the study area. The main sources of reproductive propagules for the re-establishment of the assemblage kelp were fertile sporophytes which included isolated, low density patches of M.integrifolia located within the bed

  17. Receiver Function Migration of Broadband Seismograms recorded by the International Maule Aftershock Deployment (IMAD) in Central Chile

    Science.gov (United States)

    Morell, M.; Beck, S. L.; Roecker, S. W.; Meltzer, A.; Russo, R. M.

    2011-12-01

    The Mw=8.8 Maule earthquake that occurred off the coast of Chile on February 27, 2010 is one of the largest megathrust earthquakes ever to be recorded and ruptured ~600 km of the plate boundary. This segment of the Nazca-South America plate boundary is an ideal region to investigate the processes related to the structure of the down-dip edge of the seismogenic zone, forearc wedge and subducting slab. Immediately after the Maule earthquake, international teams from France, Germany, Great Britain and the United States joined Chilean seismologists to install an array of seismic stations between 33°-38.5°S, from the coast to the foothills of the Andes to produce the International Maule Aftershock Deployment (IMAD) data set. These arrays were deployed from mid-March until the end of December 2010 in order to capture and study the aftershocks in and around the rupture zone, and to better understand crustal and mantle wedge structure. We calculated receiver functions (RFs) from P and PP phases and made Common Conversion Point stacks to image the structures in the slab and forearc wedge down to a depth of 100 km. We have identified the oceanic slab Moho on several E-W and N-S profiles at 40 to 60 km depth beneath the array and several discontinuities above the slab in the forearc. These profiles also show a large low-velocity zone beneath the northern half of the array in the forearc. In addition, we are using a 2.5D finite difference teleseismic waveform tomography technique described in Roecker et al. (2010) to image the crust and upper mantle beneath that part of the Chilean Andes occupied by the IMAD array and the earlier TIPTEQ deployment of Rietbrock et al. (2005). While the technique does not require any kind of formal source deconvolution, in sparse deployments we can apply this technique in an RF type migration by normalizing medium sensitivities. Both these techniques will improve our imaging of the down-dip limit of the seismogenic zone, forearc wedge and

  18. Late Quaternary evolution of Lago Castor (Chile, 45.6°S): Timing of the deglaciation in northern Patagonia and evolution of the southern westerlies during the last 17 kyr

    Science.gov (United States)

    Van Daele, Maarten; Bertrand, Sébastien; Meyer, Inka; Moernaut, Jasper; Vandoorne, Willem; Siani, Giuseppe; Tanghe, Niels; Ghazoui, Zakaria; Pino, Mario; Urrutia, Roberto; De Batist, Marc

    2016-02-01

    Even though Patagonia is ideally located to study climate of the southern mid-latitudes, many questions on the late Quaternary climate evolution remain unresolved. The timing of maximum glacier extent is still uncertain in vast areas, and the postglacial evolution of the Southern Westerly Wind Belt (SWWB) remains highly debated. Here, we study the sedimentary infill of a glacigenic lake (Lago Castor; 45.6°S, 71.8°W) located at the leeside of the Andes in Chilean Patagonia to i) reconstruct the deglacial evolution of the eastern flank of the Patagonian Ice Sheet (PIS), and ii) discuss postglacial changes in wind strength at a critical location where westerly wind records are critically lacking. A dense grid of high-resolution reflection-seismic data was used to reconstruct the large-scale infill history of the lake, and a radiocarbon dated sediment core penetrating all lacustrine seismic units, was retrieved. Results indicate that the deglaciation of the lake basin and its catchment occurred no later than ∼28 cal kyr BP (i.e. an early LGM), but possibly even already after MIS 4. Afterwards, the Lago Castor area was covered by a large proglacial lake that drained - possibly through an outburst flood - when the PIS outlet glaciers retreated to a critical location. Subsequently, very dry conditions caused the lake to desiccate, as evidenced by an unconformity visible on the seismic profiles and in the sediment core. This dry period likely resulted from the increased orographic effect of the PIS-covered Andes, accompanied by weaker westerlies. From ∼20 kyr BP onwards, the combination of a shrinking PIS and a southward shift of the SWWB resulted in increased precipitation, which caused the lake level to rise. After ∼17 cal kyr BP, lake sedimentation was more directly influenced by the southern westerlies, with the formation of sediment drifts resulting from strong bottom current during periods of intense westerly winds. Our results suggest a progressive increase

  19. Late Quaternary evolution of Lago Castor (Chile, 45.6°S): Timing of the deglaciation in northern Patagonia and evolution of the southern westerlies during the last 17 kyr

    Science.gov (United States)

    Van Daele, Maarten; Bertrand, Sébastien; Meyer, Inka; Moernaut, Jasper; Vandoorne, Willem; Siani, Giuseppe; Tanghe, Niels; Ghazoui, Zakaria; Pino, Mario; Urrutia, Roberto; De Batist, Marc

    2016-02-01

    Even though Patagonia is ideally located to study climate of the southern mid-latitudes, many questions on the late Quaternary climate evolution remain unresolved. The timing of maximum glacier extent is still uncertain in vast areas, and the postglacial evolution of the Southern Westerly Wind Belt (SWWB) remains highly debated. Here, we study the sedimentary infill of a glacigenic lake (Lago Castor; 45.6°S, 71.8°W) located at the leeside of the Andes in Chilean Patagonia to i) reconstruct the deglacial evolution of the eastern flank of the Patagonian Ice Sheet (PIS), and ii) discuss postglacial changes in wind strength at a critical location where westerly wind records are critically lacking. A dense grid of high-resolution reflection-seismic data was used to reconstruct the large-scale infill history of the lake, and a radiocarbon dated sediment core penetrating all lacustrine seismic units, was retrieved. Results indicate that the deglaciation of the lake basin and its catchment occurred no later than ˜28 cal kyr BP (i.e. an early LGM), but possibly even already after MIS 4. Afterwards, the Lago Castor area was covered by a large proglacial lake that drained - possibly through an outburst flood - when the PIS outlet glaciers retreated to a critical location. Subsequently, very dry conditions caused the lake to desiccate, as evidenced by an unconformity visible on the seismic profiles and in the sediment core. This dry period likely resulted from the increased orographic effect of the PIS-covered Andes, accompanied by weaker westerlies. From ˜20 kyr BP onwards, the combination of a shrinking PIS and a southward shift of the SWWB resulted in increased precipitation, which caused the lake level to rise. After ˜17 cal kyr BP, lake sedimentation was more directly influenced by the southern westerlies, with the formation of sediment drifts resulting from strong bottom current during periods of intense westerly winds. Our results suggest a progressive increase in

  20. Infrastructure Concessions in Chile

    OpenAIRE

    Gómez-Lobo, Andrés; Hinojosa, Sergio

    2000-01-01

    To increase investment in infrastructure, in the early 1990s Chiles government introduced private capital into the transport infrastructure sector, covering roads and highways, bridges, tunnels, and airports. The chosen mechanism: a concession scheme through which private firms would finance and build a given project and then operate the infrastructure for a set of number of years, recover...

  1. The Geology of Chile

    OpenAIRE

    Cabrera, Lluís; Calafat, A.; Gimeno, D.; Liesa, M.; Proenza, J.; Sàbat, F.; Sáez, Alberto; Santanach, Pere

    2008-01-01

    6 páginas.-- Book review of "The Geology of Chile", by Teresa Moreno and Wes Gibbons (eds.) (2007). Geological Society. London (United Kingdom). 414 pages, 286 figures including maps, charts and pictures; 27, 5 x 21 cm, ISBN 978-1- 86239-219-9 (hardback) and ISBN 978-1-86239-220-5 (softback).

  2. Chile's Madam President

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    After becoming the first female to win a presidential election in the socially conservative country, Chilean President-elect Michelle Bachelet created history again when unveiling a cabinet that was absolutely gender-balanced on January 30. Following similar breakthroughs of women politicians in Liberia and Germany, what happened in Chile is considered another case of women gaining power worldwide.

  3. Late Quaternary deglacial history of the Mérida Andes, Venezuela

    Science.gov (United States)

    Stansell, Nathan D.; Abbott, Mark B.; Polissar, Pratigya J.; Wolfe, Alexander P.; Bezada, Maximiliano; Rull, Valentí

    2005-10-01

    Radiocarbon-dated sediment cores from seven lakes and two bogs spanning the Cordillera de Mérida in the Venezuelan Andes were used to identify and date the regional history of late Pleistocene and Holocene glacial activity. Coring sites were selected at different elevations across a pronounced rain shadow from southeast (wet) to northwest (dry). Sediment lithostratigraphy and magnetic susceptibility, in conjunction with AMS radiocarbon dates on macrofossils and charcoal, were used to constrain deglaciation. The local expression of the Last Glacial Maximum occurred between 22 750 and 19 960 cal. yr BP. On the wetter southeastern side of the Cordillera de Mérida, glaciers had significantly retreated by 15 700 cal. yr BP, followed by several minor glacial advances and retreats between 14 850 and 13 830 cal. yr BP. At least one major glacial readvance occurred between 13 830 and 10 000 cal. yrBP in the wetter southeastern sector of the region. The drier northwest side of the Cordillera de Mérida records initial glacial retreat by 14240cal.yrBP. Multiple sites on both sides of the Mérida Andes record a further phase of extensive deglaciation approximately 10000cal.yrBP. However, the north-northwest facing Mucubají catchment remained partially glaciated until ca. 6000cal.yrBP. Deglacial ages from the Venezuelan Andes are consistently younger than those reported from the Southern Hemisphere Andes, suggesting an inter-hemispheric deglacial lag in the northern tropics of the order of two thousand years.

  4. Presencia de Malacocephalus laevis (Lowe, 1843 en montes sumergidos frente al norte de Chile, con notas sobre su contenido estomacal (Osteichthyes, Gadiformes, Macrouridae Presence of Malacocephalus laevis (Lowe, 1843 in seamounts off northern Chile, with notes about its stomach food contents (Osteichthyes, Gadiformes, Macrouridae

    Directory of Open Access Journals (Sweden)

    Jorge Oñate

    2005-11-01

    Full Text Available Se analizaron merística y morfométricamente 50 ejemplares de Malacocephalus laevis (Lowe, 1843, provenientes de la cordillera submarina de Nazca, cercana a las islas Desventuradas, Chile. De esta muestra, a 18 ejemplares se les analizó la longitud del intestino, el número de ciegos pilóricos y el contenido estomacal. Este estudio confirma la presencia de esta especie en el Pacífico suroriental y da una pauta de su tipo de alimentación en el lugar y época del año en que se obtuvieron las muestrasFifty specimens of Malacocephalus laevis (Lowe, 1843 from the Nazca Submarine Ridge, near the Desventuradas Islands, Chile, were meristic and morfometric studied ally. In eighteen specimens of the sample the length of the intestine, the number of piloric caeca and their stomach contents were analyzed. This study confirms the presence of this species in the southeast Pacific and provides new insigths on its feeding in that place and at the time of the year that were captured

  5. LANDSAT imagery of the Central Andes

    Science.gov (United States)

    Komer, C. A.; Morgan, P.

    1986-01-01

    The central Andes of South America extend from approximately 14 deg. S to 28 deg. S as an unbroken chain of mountains and volcanoes over 2000 km long. It is here that the Nazca plate dives under the South American plate at angles varying from 10 deg to 30 deg. Very little is known about the volcanoes comprising this classic, subduction-type plate margin. A catalogue of the volcanoes in the central Andes is being prepared by Dr. P.W. Francis and Dr. C.A. Wood at the NASA Lunar and Planetary Institute. At present, more than 800 volcanoes of Cenozoic age have been recognized in the chain, with an estimated 75-80 major, active Quarternary volcanoes. Approximately one hundred 1536 x 1536 pixel color composite Optronics positives were produced from six full LANDSAT Thermatic Mapper scenes and three partial TM scenes. These positives cover a large portion of the central Andes. The positives were produced from LANDSAT data using the VAX imaging package, LIPS. The scenes were first transferred from magnetic tape to disk. The LIPS package was then used to select volcanically interesting areas which were then electronically enhanced. Finally, the selected areas were transferred back to tape and printed on the Optronics equipment. The pictures are color composites using LANDSAT TM bands 7,4, and 2 in the red, green, and blue filters, respectively.

  6. Analysis of the dynamic of underground water in Agua Verde, Quebrada de Taltal, region of Antofagasta, Chile

    International Nuclear Information System (INIS)

    The extreme aridity and geological situation in northern. Chile requires an exhaustive investigation on water resources for supporting rational usage. The Direccion General de Aguas and Comision Chilena de Energia Nuclear have performed studies in arid zones in northern Chile using isotopic and hydrochemical tools. In Quebrada de Taltal's basin, located in one of the must arid arid zones of Chile (Segunda Region de Antofagasta), was studies groundwater dynamics and recharge process from a geochemical approach in terms of water quality, temperature and isotopic composition (2H, 18O, 3H, 14C). The recharge generated above 3000 m a.s.t has a slow dynamics and involve little flow (author)

  7. Mineralog??a de alteraci??n en el pozo Pte-1, campo geotermal Tinguiririca, Chile

    OpenAIRE

    Droguett, B??rbara; Morata, Diego; Clavero, Jorge; Pineda, Germ??n; Morales-Ruano, Salvador; Carrillo-Ros??a, Javier

    2012-01-01

    Este trabajo presenta los avances en el estudio mediante petrograf??a ??ptica, DRX y SEM de la mineralog??a de alteraci??n presente en el pozo PTe-1, ubicado en el campo geot??rmico Tinguiririca (Chile central). Los 813,85m de rocas perforadas pertenecen al Complejo Volc??nico Tinguiririca (Pleistoceno-Holoceno) formado por lavas, tobas y brechas volc??nicas de composici??n andes??tica. Sobre la base de las asociaciones minerales se ha determinado dos zonas de alteraci??n principales. La de m...

  8. Alimentación y relaciones tróficas del pez espada (Xiphias gladius Linnaeus, 1758), frente a Chile centro-norte durante 2005 Feeding and trophic relationships of the swordfísh (Xiphias gladius Linnaeus, 1758), off central and northern Chile during 2005

    OpenAIRE

    Sergio Letelier; Roberto Melendez; Esteban Carreño; Sebastián López; Patricio Barría

    2009-01-01

    Se analizaron 126 estómagos de pez espada (Xiphias gladius), capturados entre los 25° y 34°S y 78° y 90°W, por barcos palangreros de la pesquería industrial frente a Chile centro-norte. Del total de estómagos analizados, 54 se encontraron vacíos (42,9%) y 72 (57,1%) presentaron sus estómagos con contenidos, de estos últimos la proporción sexual correspondió a 32 machos (44,4%), 37 hembras (51,4%o) y 3 indeterminados (4,2%o). Para el análisis de contenidos estomacales se utilizaron los métodos...

  9. Un nuevo espécimen de cocodrilo marino del Jurásico Medio del norte de Chile: revalidación de Metriorhynchus westermanni (Crocodyliformes: Metriorhynchidae A new specimen of marine crocodile from the Middle Jurassic of northern Chile: revalidation of Metriorhynchus westermanni (Crocodyliformes: Metriorhynchidae

    Directory of Open Access Journals (Sweden)

    Zulma Gasparini

    2008-07-01

    Full Text Available Se revalida la especie Metriorhynchus -westermanni Gasparini a partir de un nuevo espécimen de cocodrilo marino caloviano (Metriohrynchidae hallado en el curso medio de quebrada Cherejara, Sierra del Medio, Región de Antofagasta, Chile. El análisis del neurocráneo y de los huesos asociados demuestra que el holotipo de M. westermanni no es unjuvenil deMetriohrynchus casamiquelai Gasparini y Chong, como anteriormente se propuso. Varias diferencias morfológicas tales como frontal y parietal en el mismo plano, ausencia de depresión medial en el sector interorbital del frontal, piso de la fosa supratemporal plano y horizontal, narinas internas con forma de lágrima con la base más ancha caudalmente y separadas por un septo completo, justifican revalidar a M. westermanni. De esta manera aumenta la diversidad de cocodrilos marinos jurásicos en el oeste del Gondwana, con predominio de registros chilenos en el Jurásico Medio.Anew specimen of a Callo vian marine crocodile (Metriorhynchidae, found in the middle course of quebrada Cherejara, Sierra del Medio, Región de Antofagasta, Chile, allows the revalidation of the species Metriorhynchus westermanni Gasparini. The analysis of the braincase and associated bones shows that the holotype ofMetriohrynchus westermanni is not a juvenile ofM casamiquelai Gasparini and Chong, as recently proposed. Revalidation of M. westermanni is supported by several morphological differences such as frontal and parietal on a single plane, absence of medial depression on the interorbital section of the frontal, base of the supratemporal fossa flat and horizontal, internal nares drop-shaped with the base wider caudally and separated by a complete septum. The revalidation ofM westermanni increases the diversity of Jurassic marine crocodiles in West Gondwana, prevailing the Chilean forms during the Mddle Jurassic.

  10. Active Folding of the Tame Anticline, Eastern Foothills, Colombian Andes

    Science.gov (United States)

    Veloza-Fajardo, G.; Taylor, M. H.; Mora, A.; Stockli, D. F.

    2011-12-01

    We integrate neotectonic mapping and interpretation of seismic reflection profiles to evaluate the kinematics of folding and development of the Quaternary Tame anticline and Cusiana fault at 6.5 N Latitude in the eastern foothills of the Eastern Cordillera of Colombia. The Tame anticline is located approximately 660 km to the east of the Nazca-South America and 810 km to the south of the Caribbean-South America subduction zones plate boundaries in a retroarc foreland basin setting. The Tame anticline is an elongated, N15E trending structure, 14 km long N-S by 6 km wide E-W, that represents the most frontal active structure of the northern Colombian Andes. The Tame fold is related to the east-directed Cusiana fault that day lights to the south. Seismic reflection profiles indicate the Cusiana fault is a listric, west-dipping blind structure. The east flowing antecedent Macaguana creek has incised the Tame fold forming three prominent terrace levels, uplifted approximately 220, 150 and 100 meters, above current river levels. The surfaces were sampled for terrestrial cosmogenic nuclides using the depth profiling approach to account for inheritance. Surface exposure ages from the highest to lowest surfaces are 93.9, 50.8 and 32.4 kyrs at the 1σ level respectively, which were calculated using Monte Carlo methods. Trishear kinematic modeling was used to retrodeform the folding history and based on the surface abandonment ages, we will present shortening rates at millennial timescales.

  11. Millennial-scale vegetation changes in the tropical Andes using ecological grouping and ordination methods

    Science.gov (United States)

    Urrego, Dunia H.; Hooghiemstra, Henry; Rama-Corredor, Oscar; Martrat, Belen; Grimalt, Joan O.; Thompson, Lonnie; Bush, Mark B.; González-Carranza, Zaire; Hanselman, Jennifer; Valencia, Bryan; Velásquez-Ruiz, César

    2016-03-01

    We compare eight pollen records reflecting climatic and environmental change from northern and southern sites in the tropical Andes. Our analysis focuses on the last 30 000 years, with particular emphasis on the Pleistocene to Holocene transition. We explore ecological grouping and downcore ordination results as two approaches for extracting environmental variability from pollen records. We also use the records of aquatic and shoreline vegetation as markers for lake level fluctuations and moisture availability. Our analysis focuses on the signature of millennial-scale climate variability in the tropical Andes, in particular Heinrich stadials (HS) and Greenland interstadials (GI). The pollen records show an overall warming trend during the Pleistocene-Holocene transition, but the onset of post-glacial warming differs in timing among records. We identify rapid responses of the tropical vegetation to millennial-scale climate variability. The signatures of HS and the Younger Dryas are generally recorded as downslope upper forest line (UFL) migrations in our transect, and are likely linked to air temperature cooling. The GI1 signal is overall comparable between northern and southern records and indicates upslope UFL migrations and warming in the tropical Andes. Our marker for lake level changes indicated a north-to-south difference that could be related to moisture availability. The air temperature signature recorded by the Andean vegetation was consistent with millennial-scale cryosphere and sea surface temperature changes but suggests a potential difference between the magnitude of temperature change in the ocean and the atmosphere. We also show that arboreal pollen percentage (AP %) and detrended correspondence analysis (DCA) scores are two complementary approaches to extract environmental variability from pollen records.

  12. Spent Fuel in Chile

    International Nuclear Information System (INIS)

    The government has made a complete and serious study of many different aspects and possible road maps for nuclear electric power with strong emphasis on safety and energy independence. In the study, the chapter of SFM has not been a relevant issue at this early stage due to the fact that it has been left for later implementation stage. This paper deals with the options Chile might consider in managing its Spent Fuel taking into account foreign experience and factors related to safety, economics, public acceptance and possible novel approaches in spent fuel treatment. The country’s distinctiveness and past experience in this area taking into account that Chile has two research reactors which will have an influence in the design of the Spent Fuel option. (author)

  13. Waste management in Chile

    International Nuclear Information System (INIS)

    The main radioactive waste management issues to be faced by the Chilean Nuclear Energy Commission (CCHEN) are discussed herein. Research reactor spent fuel management is the most outstanding challenge at the beginning of the 21st century. Interim storage appears to be the most promising alternative, allowing fuel safekeeping until a definitive step is taken. The situation regarding radioactive waste resulting from radioisotope applications in Chile will not undergo considerable change in the near future. Low and intermediate level radioactive waste management is being safely performed followed by interim storage of conditioned wastes. The strategy in the radioactive waste management plan, to be described as well, is meant to ensure the safe storage of radioactive wastes produced in Chile. (author)

  14. Changing Student Attitudes using Andes, An Intelligent Homework System

    Science.gov (United States)

    van de Sande, Brett; Vanlehn, Kurt; Treacy, Don; Shelby, Bob; Wintersgill, Mary

    2007-03-01

    The size of introductory physics lectures often inhibits personal homework assistance and timely corrective feedback. Andes, an intelligent homework help system designed for two semesters of introductory physics, can fill this need by encouraging students to use sound problem solving techniques and providing immediate feedback on each step of a solution. On request, Andes provides principles-based hints based on previous student actions. A multi-year study at the U.S. Naval Academy demonstrates that students using Andes perform better than students working the same problems as graded pencil and paper homeworks. In addition, student attitude surveys show that Andes is preferred over other homework systems. These findings have implications for student attitudes toward, and mastery of, physics. See http://www.andes.pitt.edu for more information.

  15. Range expansion of Oligoryzomys longicaudatus (Rodentia, Sigmodontinae in Patagonian Chile, and first record of Hantavirus in the region Ampliación del rango de distribución de Oligoryzomys longicaudatus (Rodentia, Sigmodontinae en la Patagonia de Chile y primer registro de Hantavirus en la región

    Directory of Open Access Journals (Sweden)

    SEBASTIÁN BELMAR-LUCERO

    2009-06-01

    Full Text Available At present, 20 species of Oligoryzomys (Rodentia, Sigmodontinae are recognized in the Neotropical region, most of them distinguished by their karyotypes, which fluctuates between 46-70 chromosomes. Two species are currently recognized in Chile, Oligoryzomys longicaudatus (Bennet, 1832; "colilargo" or the long-tailed pygmy rice rat; 2n = 56, which ranges from 27° to approximately 51° S, and O. magellanicus (Bennet, 1836; Magellanic pygmy rice rat; 2n = 54, south of 51° S in the Patagonian region of Chile and Argentina. As part of an ongoing research on the southern Patagonia of Chile, we report the results of small mammal samplings in six localities. We karyotyped 28 specimens and we also sequenced the hypervariable mtDNA region I in 22 individuals, aligning these sequences with an under development phylogeny of O. longicaudatus. We also evaluated the serology and viral charge in all captured specimens to detect the presence of antibodies to Andes virus (ANDV through Strip Immunoblot Assay (SIA, and of viral genome by RT-PCR. The results consistently showed that the karyotype of southern Patagonia specimens was 2n = 56, equal to that of O. longicaudatus, and that individuals from this area do not differentiate phylogenetically from those of the northern range of distribution. In addition, the serology showed the presence of antibodies IgG anti-ANDV and of viral genome in heart, kidney, spleen, and lungs of a single specimen of Oligoryzomys from the locality of Fuerte Bulnes in the Magallanes region. We conclude that all specimens trapped south of 51° S correspond to Oligoryzomys longicaudatus, thus expanding the distribution of this specie! from 51° to at least 55° S. The results also extended the disiribution of the Andes strain of Hantavirus to southernmost Patagonia.Actualmente se reconocen 20 especies de Oligoryzomys (Rodentia, Sigmodontinae en la región Neotropical, la mayoría de ellas distinguidas por sus cariotipos, los que fluct

  16. Contrasting climate change impact on river flows from high-altitude catchments in the Himalayan and Andes Mountains.

    Science.gov (United States)

    Ragettli, Silvan; Immerzeel, Walter W; Pellicciotti, Francesca

    2016-08-16

    Mountain ranges are the world's natural water towers and provide water resources for millions of people. However, their hydrological balance and possible future changes in river flow remain poorly understood because of high meteorological variability, physical inaccessibility, and the complex interplay between climate, cryosphere, and hydrological processes. Here, we use a state-of-the art glacio-hydrological model informed by data from high-altitude observations and the latest climate change scenarios to quantify the climate change impact on water resources of two contrasting catchments vulnerable to changes in the cryosphere. The two study catchments are located in the Central Andes of Chile and in the Nepalese Himalaya in close vicinity of densely populated areas. Although both sites reveal a strong decrease in glacier area, they show a remarkably different hydrological response to projected climate change. In the Juncal catchment in Chile, runoff is likely to sharply decrease in the future and the runoff seasonality is sensitive to projected climatic changes. In the Langtang catchment in Nepal, future water availability is on the rise for decades to come with limited shifts between seasons. Owing to the high spatiotemporal resolution of the simulations and process complexity included in the modeling, the response times and the mechanisms underlying the variations in glacier area and river flow can be well constrained. The projections indicate that climate change adaptation in Central Chile should focus on dealing with a reduction in water availability, whereas in Nepal preparedness for flood extremes should be the policy priority. PMID:27482082

  17. La quinua en Chile

    OpenAIRE

    Martinez, Enrique A.; Fuentes, Francisco F.; Chia, Eduardo; Namdar-Irani, Mina; Olguin, Pablo; Saa, Constanza; Thomet, Max; Vidal, Alejandra

    2014-01-01

    La biogeografía de la quinua (Chenopodium quinua Willd.) presenta una visión global de un cultivo menor en la agricultura chilena que tiene una amplia extensión geográfica (18°S-47°S). Su alta diversidad genética demuestra que es una de las especies de mayor importancia en Los Andes de Sudamérica. El proceso de domesticación de la quinua se ha realizado en distintas zonas geográficas, lo cual ha significado la existencia de una amplia variación de caracteres morfológicos y de adaptación medio...

  18. Cirripedios en la dieta del molusco herbívoro Chiton granosus Frembly, 1827 (Mollusca, Placophora presente en el intermareal rocoso de Iquique, norte de Chile Barnacles in the diet of the molluscan grazer Chiton granosus Frembly, 1827 (Mollusca, Placophora present on the intertidal rocky shore of Iquique, northern Chile

    Directory of Open Access Journals (Sweden)

    Moisés A Aguilera

    2005-05-01

    Full Text Available Se entrega información preliminar cuantitativa, sobre la presencia de cirripedios en estados de larvas cypris y estados post-metamórficos en la dieta del molusco Chiton granosus Frembly, 1827 (Mollusca, Placophora recolectado en Iquique, Chile. En diciembre de 2000, se observó la presencia de larvas cypris y post-metamórfico con una importante abundancia relativa porcentual (N = 30, 54,1 y 39,9%, respectivamente y con una frecuencia de ocurrencia del 100% en el total de estómagos. Además, se registró una alta frecuencia de larvas cypris (F% = 67 en la porción final del intestino, de éstas 15 presentaron signos de actividad vital (movimiento de apéndices en el 45% del total de estómagos analizados. La ingesta de cirripedios en estados cypris y post-metamórficos, fue observada también con una alta frecuencia durante cinco meses de estudio (N = 10, 96% ± 6,5 y 78% ± 23,6Preliminary quantitative information is given on the presence of barnacle cyprids and post-metamorphic stages in the diet of the molluscan grazer Chiton granosus Frembly 1827 (Mollusca: Placophora sampled at Iquique, Chile. In December 2000, we observed the presence of barnacle cyprids and post-metamorphic stages at a high relative percentage of abundance (N = 30, 54,1% and 39,9%, respectively and they were frequent in all of the individuals analyzed. Moreover, a high frequency of ocurrence of cyprid larvae (F% = 67 was recorded in the distal portion of the intestine; of these larvae, 15 were observed with signs of vital activity (appendage movement in 45% of all the stomachs analyzed. Ingestion of barnacle cyprids and post-metamorphic stages was observed at a high frequency throughout the five months of the study (N = 10, 96% ± 6,5 and 78% ± 23,6

  19. Primary Medical Care in Chile

    DEFF Research Database (Denmark)

    Scarpaci, Joseph L.

    Primary medical care in Chile: accessibility under military rule [Front Cover] [Front Matter] [Title Page] Contents Tables Figures Preface Chapter 1: Introduction Chapter 2: The Restructuring of Medical Care Financing in Chile Chapter 3: Inflation and Medical Care Accessibility Chapter 4: Help......-Seeking Behavior of the Urban Poor Chapter 5: Spatial Organization and Medical Care Accessibility Chapter 6: Conclusion...

  20. NON-SYMBIOTIC NITROGEN FIXATION, NET NITROGEN MINERALIZATION AND DENITRIFICATION IN EVERGREEN FORESTS OF CHILOÉ ISLAND, CHILE: A COMPARISON WITH OTHER TEMPERATE FORESTS FIJACION NO-SIMBIOTICA, MINERALIZACION NETA DEL NITROGENO Y DESNITRIFICACION EN BOSQUES SIEMPREVERDES DE CHILOE, CHILE: UNA COMPARACION CON OTROS BOSQUES TEMPLADOS

    OpenAIRE

    C.A. Pérez; M.R. Carmona; Armesto, J. J.

    2003-01-01

    Temperate forests in southern Chile offer unique opportunities for studying biogeochemical cycles in the absence of industrial air pollution. Here we compare three important fluxes of the nitrogen (N) cycle in temperate forests of southern Chile, non-symbiotic N fixation, net N mineralization and denitrification, with data from northern temperate forests more affected by air pollution. We studied five evergreen, old-growth forests and one second-growth forest in Chiloé Island, southern Chile....

  1. Chile rural electrification cooperation

    Energy Technology Data Exchange (ETDEWEB)

    Flowers, L. [National Renewable Energy Lab., Golden, CO (United States)

    1997-12-01

    The author describes a joint program to use renewables for rural electrification projects in Chile. The initial focus was in a limited part of the country, involving wind mapping, pilot project planning, training, and development of methodologies for comparative evaluations of resources. To this point three wind hybrid systems have been installed in one region, as a part of the regional private utility, and three additional projects are being designed. Additional resource assessment and training is ongoing. The author points out the difficulties in working with utilities, the importance of signed documentation, and the need to look at these programs as long term because of the time involved in introducing such new technologies.

  2. Biomasa en Chile

    OpenAIRE

    Nilsson Cifuentes, Gabriel; Rodríguez Monroy, Carlos

    2012-01-01

    El artículo presenta el desarrollo de la biomasa en Chile, dentro del complejo marco energético existente en el país, el cual, aún no logra potenciar e incentivar el desarrollo de energías renovables y depende fuertemente de los combustibles fósiles, acrecentando el riesgo latente de sufrir una crisis energética, en el mediano plazo, producto de la paulatina incorporación de nuevas centrales generadoras de energías, que satisfagan la creciente demanda energética pronosticada. Este ar...

  3. Chile: Transantiago recargado Chile: Transantiago Reloaded

    Directory of Open Access Journals (Sweden)

    RODRIGO MARDONES Z

    2008-01-01

    Full Text Available El 2007 fue el segundo año del gobierno de Michelle Bachelet. Se trató de un año sin elecciones; con un buen desempeño económico, a pesar de una inflación creciente en los últimos meses; y marcado por la discusión sobre escándalos de corrupción. Sin embargo, lo que más afectó al Gobierno fue la desastrosa puesta en marcha de la reforma al sistema de transporte público de la capital: Transantiago. Este puso un velo sobre los importantes avances en materias previsionales y educacionales, cuestionando no sólo la capacidad ejecutiva del Gobierno, sino que profundizando un flanco de indisciplina al interior de la coalición oficialista (Concertación; síntoma de su desgaste después de 17 años ocupando la Presidencia de Chile.The year 2007 was the second in Michelle Bachelet’s presidencial term. It was a year free of elections, exhibiting a fairly good economic performance, despite the high rate of inflation shown during the last months. Public discussion on corruption escandals was frequent; however, the most important issue was the disestrous beginning of the reform on the public transportation system of the country’s capital: Transantiago. This has placed a veil over the important achievements on the pension system and education, questioning not only the government’s capacity, but also opening and edge of indiscipline within the ruling coalition (Concertación, which is a symtom of its erosion after 17 years in the presidential office.

  4. Evolution of crustal thickening in the central Andes, Bolivia

    Science.gov (United States)

    Eichelberger, Nathan; McQuarrie, Nadine; Ryan, Jamie; Karimi, Bobak; Beck, Susan; Zandt, George

    2015-09-01

    Paleoelevation histories from the central Andes in Bolivia have suggested that the geodynamic evolution of the region has been punctuated by periods of large-scale lithospheric removal that drive rapid increases in elevation at the surface. Here, we evaluate viable times and locations of material loss using a map-view reconstruction of the Bolivian orocline displacement field to forward-model predicted crustal thicknesses. Two volumetric models are presented that test assumed pre-deformation crustal thicknesses of 35 km and 40 km. Both models predict that modern crustal thicknesses were achieved first in the northern Eastern Cordillera (EC) by 30-20 Ma but remained below modern in the southern EC until ≤10 Ma. The Altiplano is predicted to have achieved modern crustal thickness after 10 Ma but only with a pre-deformation thickness of 50 km, including 10 km of sediment. At the final stage, the models predict 8-25% regional excess crustal volume compared to modern thickness, largely concentrated in the northern EC. The excess predicted volume from 20 to 0 Ma can be accounted for by: 1) crustal flow to the WC and/or Peru, 2) localized removal of the lower crust, or 3) a combination of the two. Only models with initial crustal thicknesses >35 km predict excess volumes sufficient to account for potential crustal thickness deficits in Peru and allow for lower crustal loss. However, both initial thickness models predict that modern crustal thicknesses were achieved over the same time periods that paleoelevation histories indicate the development of modern elevations. Localized removal of lower crust is only necessary in the northern EC where crustal thickness exceeds modern by 20 Ma, prior to paleoelevation estimates of modern elevations by 15 Ma. In the Altiplano, crustal thicknesses match modern values at 10 Ma and can only exceed modern values by 5 Ma, post-dating when modern elevations were thought to have been established. Collectively, these models predict that

  5. 27 CFR 9.154 - Chiles Valley.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Chiles Valley. 9.154... Chiles Valley. (a) Name. The name of the viticultural area described in this section is “Chiles Valley.” (b) Approved maps. The appropriate maps for determining the boundary of the Chiles...

  6. The age and constitution of Cerro Campanario, a mafic stratovolcano in the Andes of central Chile

    Science.gov (United States)

    Hildreth, W.; Singer, B.; Godoy, E.; Munizaga, F.

    1998-01-01

    Cerro Campanario, a towering landmark on the continental divide near Paso Pehuenche, is a glacially eroded remnant of a mafic stratovolcano that is much younger than previously supposed. Consisting of fairly uniform basaltic andesite, rich in olivine and plagioclase, the 10-15 km3 edifice grew rapidly near the end of the middle Pleistocene, about 150-160 ka, as indicated by 40Ar/39Ar and unspiked K-Ar analyses of its lavas.

  7. The age and constitution of Cerro Campanario, a mafic stratovolcano in the Andes of Central Chile

    OpenAIRE

    Wes Hildreth; Brad Singer; Estanislao Godoy; Francisco Munizaga

    1998-01-01

    ABSTRACT Cerro Campanario, a towering landmark on the continental divide near Paso Pehuenche, is a glacially eroded remnant of a mafic stratovolcano that is much younger than previously supposed. Consisting of fairly uniform basaltic andesite, rich in olivine and plagioclase, the 10-15 km³ edifice grew rapidly near the end of the middle Pleistocene, about 150-160 ka, as indicated by 40Ar/39Ar and unspiked K-Ar analyses of its lavas.La edad y formación del cerro Campanario, un estratovolcán má...

  8. Annual narrative report: Lake Andes National Wildlife Refuge, Karl Mundt National Wildlife Refuge, and Lake Andes Wetland Management District: Calendar year 1975

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This collection of monthly activity reports summarizes activities on Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR during the 1975 calendar year. Resource...

  9. A DRONE FLIGHT OVER PARANAL, CHILE

    CERN Document Server

    2016-01-01

    Aerial clip (shot using a drone and a Go pro) describing ESO's astronomical observatory facilities in the Atacama desert, Northern Chile. Locations covered by the drone flight include Cerro Paranal, with the Residencia (external and internal views) and the Very Large Telescope facility on Cerro Paranal, from above and with a peek into Unit Telescope 1 and its 8,2 m diameter mirror; final image on Cerro Armazones, the site chosen for building ESO's next telescope, the E-ELT (European Extremely Large Telescope). With a 39-metre main mirror, it will be the largest optical/near-infrared telescope in the world. The Argentinian Codillera with the Llullaillaco volcano are visible in the background.

  10. Evolución de la serie Microphyllae (Adesmia, Fabaceae en la Cordillera de los Andes: una perspectiva biogeográfica Evolution of the series Microphyllae (Adesmia, Fabaceae in the Andean Cordillera: a biogeographic approach

    Directory of Open Access Journals (Sweden)

    MARITZA A. K. MIHOC

    2006-09-01

    largest number of described species, and its distribution includes most of the genus range. The biogeographic evolutionary history of this series, as well as the genus, is unclear. Some hypotheses suggest that the development of the Andes affected the evolution of the genus Adesmia, but there is no evidence about the processes (e.g., dispersal or vicariance involved. In this study we used a panbiogeographic approach, and based on the distribution of 22 species of this series we carried out a track analysis and a parsimony analysis of endemicity (PAE. Distribution area of the series was divided in quadrats of 1° x 1° (Latitude x Longitude, and latitudinal and longitudinal belts of 1º. All the species presented a distribution associated with the Andes, and most of them presented both latitudinally and longitudinally restricted distributions. Five generalized tracks and two nodes were found. All tracks were longitudinally associated with the Andean range. Nodes could be associated with the South American Transition Zone. PAE based on latitudinal belts split the total area in two sub-areas (north and south, where the limit between them is central Chile (ca. 33° S. This division is characterized by the presence of A. miraflorensis in the northern zone, and A. volckmannii in the southern zone. Our results suggest a recent differentiation within the series Microphyllae, which may have resulted from isolation of populations along the Andes, i.e., vicariance events fragmented the distribution of species and subsequently caused differentiation. It seems likely that this separation has occurred latitudinally, as suggested by the latitudinal sequence of generalized tracks

  11. Intraseasonal variability of organized convective systems in the Central Andes: Relationship to Regional Dynamical Features

    Science.gov (United States)

    Mohr, K. I.; Slayback, D. A.; Nicholls, S.; Yager, K.

    2013-12-01

    The Andes extend from the west coast of Colombia (10N) to the southern tip of Chile (53S). In southern Peru and Bolivia, the Central Andes is split into separate eastern and western cordilleras, with a high plateau (≥ 3000 m), the Altiplano, between them. Because 90% of the Earth's tropical mountain glaciers are located in the Central Andes, our study focuses on this region, defining its zonal extent as 7S-21S and the meridional extent as the terrain 1000 m and greater. Although intense convection occurs during the wet season in the Altiplano, it is not included in the lists of regions with frequent or the most intense convection. The scarcity of in-situ observations with sufficient density and temporal resolution to resolve individual storms or even mesoscale-organized cloud systems and documented biases in microwave-based rainfall products in poorly gauged mountainous regions have impeded the development of an extensive literature on convection and convective systems in this region. With the tropical glaciers receding at unprecedented rates, leaving seasonal precipitation as an increasingly important input to the water balance in alpine valley ecosystems and streams, understanding the nature and characteristics of the seasonal precipitation becomes increasingly important for the rural economies in this region. Previous work in analyzing precipitation in the Central Andes has emphasized interannual variability with respect to ENSO, this is the first study to focus on shorter scale variability with respect to organized convection. The present study took advantage of the University of Utah's Precipitation Features database compiled from 14 years of TRMM observations (1998-2012), supplemented by field observations of rainfall and streamflow, historical gauge data, and long-term WRF-simulations, to analyze the intraseasonal variability of precipitating systems and their relationship regional dynamical features such as the Bolivian High. Through time series and

  12. Hydrogeochemistry of thermal springs in saline salar-like environments in the High Andes

    Science.gov (United States)

    Lagos Durán, L. V.; Reich, M.; Achurra, L.; Morata, D.

    2014-12-01

    Evaporitic deposits and precipitates represent significant sinks of mobile cations (Li, As, B) and halides (Cl, I) in salar-like basin environments along the Andean volcanic belt in northern Chile. Li and B are particularly interesting because of their high concentrations in evaporitic minerals and geothermal waters in the region. Although these compositional features have been previously recognized in high-altitude salt lakes in northern Chile, the nature and extent of mixing processes between true evaporitic and geothermal endmembers in such environments is poorly understood. In a context where geothermal targeting methods need to be increasingly precise, a clearer understanding of what controls the localization of concealed geothermal resources is a prerequisite for more efficient exploration. Therefore, it is necessary to constrain surface saline inputs that can mask the deep imprints of the geothermal reservoir. On this basis, northern Chile offers a unique opportunity to test these features due to the large number of evaporitic closed basins containing thermal springs. To date, only a very limited number of studies have reported trace element concentrations and B, Li and Sr isotopes in salar-like waters aimed at differentiating the relative contributions of both members. In this study, we sampled water from high-altitude lakes with and without surficial thermal activity. This was complemented with geothermal water analyses from northern Chile and previously published data. In addition, we report preliminary dissolution experiments of evaporite minerals (e.g. ulexite, halite, gypsum, aragonite) to pure distilled water. These minerals were taken from two selected hydrological domains, located in the southern and northern part of the Chilean Central Volcanic Zone. Geochemical analyses of water run products from the aforementioned experiments at different temperatures (25 and 87°C, 500 hours of interaction each), confirmed that selected common elements (Cl, Li

  13. Alimentación y relaciones tróficas del pez espada (Xiphias gladius Linnaeus, 1758, frente a Chile centro-norte durante 2005 Feeding and trophic relationships of the swordfísh (Xiphias gladius Linnaeus, 1758, off central and northern Chile during 2005

    Directory of Open Access Journals (Sweden)

    Sergio Letelier

    2009-01-01

    Full Text Available Se analizaron 126 estómagos de pez espada (Xiphias gladius, capturados entre los 25° y 34°S y 78° y 90°W, por barcos palangreros de la pesquería industrial frente a Chile centro-norte. Del total de estómagos analizados, 54 se encontraron vacíos (42,9% y 72 (57,1% presentaron sus estómagos con contenidos, de estos últimos la proporción sexual correspondió a 32 machos (44,4%, 37 hembras (51,4%o y 3 indeterminados (4,2%o. Para el análisis de contenidos estomacales se utilizaron los métodos numéricos, de frecuencia, gravimétricos e índice de importancia relativa (IIR. Los cefalópodos fueron el alimento principal (%IIR > 90, mientras que los peces aparecen como alimento secundario (%IIR A total of 126 sword-fish (Xiphias gladius stomach were analyzed. The stomachs were obtained from specimens captured within the 25° to 34°S and 78° to 90°W área, by industrial longline vessels. Only 72 (57.1% of the total stomach had food ítems in their stomachs, whit a sex proportion of 32 males (44.4%o, 37 females (51.4% and 3 indeterminate (4.2%. Traditional methods for the stomach contents analysis such as the numeric, frequency of occurrence, gravimetric and índex of relative importance (IRI were used. Cephalopods were the main food ítems (%IIR > 90 followed by the fishes (%IIR < 4. The squid (Dosidicus gigas was the principal food in this study (%IIR = 85.1. No significant differences were found between the feeding of males and females of swordfishes (U = 81; p = 0.4862, p < 0.05. A cluster analysis showed higher stomach contents similarity between fall and winter than those from spring, within the size groups the I group was different than others and finally, the feeding from zone 3 were different from others zones.

  14. Lake Andes Easement Refuges: Narrative report: September to December, 1946

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This narrative report summarizes activities on Lake Andes NWR between September and December of 1946. Water conditions, waterfowl, furbearers, maintenance and...

  15. Relationship between the genetic structure of the Andean toad Rhinella spinulosa (Anura: Bufonidae and the northern Chile landscape (21°- 24° S Relación entre la estructura genética del sapo andino Rhinella spinulosa (Anura: Bufonidae y el paisaje del norte de Chile (21°- 24° S

    Directory of Open Access Journals (Sweden)

    CAROLINA E GALLARDO

    2011-09-01

    Full Text Available We analyzed the relationship of landscape and environmental features on the genetic differentiation of Rhinella spinulosa (Wiegmann, 1834 in the Altiplano of Antofagasta (Chile. We performed three types of analyses at different spatial scales: (1 Considering all populations; (2 Grouping populations by watershed and by sub-watershed; and (3 Using the results of a spatial analysis of molecular variation (SAMOVA. Landscape features were incorporated using Geographic Information Systems, with three hypothetical dispersal models: (1 Euclidean distance (null model; (2 Least cost based on wetland locations; and (3 Least cost based on least slopes. We also included differences in temperature, precipitation and altitude among localities. The Akaike information criterion was used to select the best model and the relative importance of each variable in the model was estimated with partial regressions. We found a high genetic differentiation among populations (Fst = 0.693 and isolation by distance (r = 0.767. AMOVA showed that the watersheds explained 8.67 % of the genetic variance and sub-watersheds 35.99 %. At the largest spatial scale, considering all populations, the model that best explained genetic differentiation included Euclidean distance, altitude and annual precipitation. At a smaller scale, in two of three sub-watersheds (Río San Pedro and Salar de Atacama the genetic differentiation was best explained by landscape variables (principally temperature and altitude. At the smallest scale, considering those populations that have diverged recently detected by SAMOVA, the genetic differentiation was best explained by the wetland-based route and annual precipitation. This approach revealed the importance of landscape features in the colonization of R. spinulosa in this zone.Se evaluó la relación entre las características del paisaje y ambientales y la diferenciación genética de Rhinella spinulosa en el altiplano de la Región de Antofagasta

  16. Recording of ocean-climate changes during the last 2,000 years in a hypoxic marine environment off northern Chile (23°S Registro de cambios océano-climáticos durante los últimos 2000 años en un ambiente marino hipóxico en el norte de Chile (23°S

    Directory of Open Access Journals (Sweden)

    LUC ORTLIEB

    2000-06-01

    Full Text Available Atmosphere-ocean interactions are particularly strong along the Chile-Peru coast and largely account for the extreme aridity of the Atacama Desert. Near the center of the driest part of this coastal desert, we found that the embayment Bahía Mejillones constitutes an unusually favorable setting for the formation and subsequent preservation of a sedimentary record of the successive oceanographic conditions of the last few thousand years. This work deals with relative abundance of various bio-indicators, including fish scales, foraminifers and phytoplankton, with a centimetre-scale resolution, in several gravity cores taken from 80 to 120 m depth, in a low-oxygen environment. We use this information to document ocean-climate changes at decadal to centennial time scales in the region. Radiocarbon dating on the bulk organic-rich sediment provides the chronological framework for the observed paleoceanographic changes. We interpret that an episode of relatively warmer water, with a stratified water column and enhanced anoxic ( 0.3 ml l-1 O2 conditions at the bottom of the water column, may correspond to the Little Ice Age (16th to mid-19th centuries. During the first millennium of our era, two thin sedimentary layers which present similarities with the bed assigned to the warm episode are interpreted as possible remnants of very strong, or " mega " El Niño events. The study confirms that Bahía Mejillones sediments did record ocean-climate changes with a very high time-resolution, and thus deserve a closer attention to investigate the ocean-atmosphere interactions over the last few thousand yearsLas interacciones océano-atmósfera son particularmente fuertes a lo largo de la costa de Chile y Perú y explican en gran parte la extrema aridez del desierto de Atacama. Cerca del sector más seco del desierto costero, hemos encontrado que la bahía semi-cerrada de Bahía Mejillones constituye un sitio particularmente favorable para la formación y

  17. Description and phylogeny of three new species of Synophis (Colubridae, Dipsadinae) from the tropical Andes in Ecuador and Peru

    Science.gov (United States)

    Torres-Carvajal, Omar; Echevarría, Lourdes Y.; Venegas, Pablo J.; Germán Chávez; Camper, Jeffrey D.

    2015-01-01

    Abstract The discovery of three new species of Synophis snakes from the eastern slopes of the tropical Andes in Ecuador and Peru is reported. All previous records of Synophis bicolor from eastern Ecuador correspond to Synophis bogerti sp. n., which occurs between 1000–1750 m along a large part of the Amazonian slopes of the Ecuadorian Andes. In contrast, Synophis zamora sp. n. is restricted to southeastern Ecuador, including Cordillera del Cóndor, between 1543–1843 m. Synophis insulomontanus sp. n. is from the eastern slopes of the Andes in central and northern Peru, between 1122–1798 m, and represents the first record of Synophis from this country. All three new species share in common a large lateral spine at the base of the hemipenial body. A molecular phylogenetic tree based on three mitochondrial genes is presented, including samples of Diaphorolepis wagneri. Our tree strongly supports Synophis and Diaphorolepis as sister taxa, as well as monophyly of the three new species described here and Synophis calamitus. Inclusion of Synophis and Diaphorolepis within Dipsadinae as sister to a clade containing Imantodes, Dipsas, Ninia, Hypsiglena and Pseudoleptodeira is also supported. PMID:26798310

  18. Southernmost Andes and South Georgia Island, North Scotia Ridge: Zircon U-Pb and muscovite {40Ar }/{39Ar } age constraints on tectonic evolution of Southwestern Gondwanaland

    Science.gov (United States)

    Mukasa, Samuel B.; Dalziel, Ian W. D.

    1996-11-01

    Zircon U-Pb and muscovite {40Ar }/{39Ar } isotopic ages have been determined on rocks from the southernmost Andes and South Georgia Island, North Scotia Ridge, to provide absolute time constraints on the kinematic evolution of southwestern Gondwanaland, until now known mainly from stratigraphic relations. The U-Pb systematics of four zircon fractions from one sample show that proto-marginal basin magmatism in the northern Scotia arc, creating the peraluminous Darwin granite suite and submarine rhyolite sequences of the Tobifera Formation, had begun by the Middle Jurassic (164.1 ± 1.7 Ma). Seven zircon fractions from two other Darwin granites are discordant with non-linear patterns, suggesting a complex history of inheritances and Pb loss. Reference lines drawn through these points on concordia diagrams give upper intercept ages of ca. 1500 Ma, interpreted as a minimum age for the inherited zircon component. This component is believed to have been derived from sedimentary rocks in the Gondwanaland margin accretionary wedge that forms the basement of the region, or else directly from the cratonic "back stop" of that wedge. Ophiolitic remnants of the Rocas Verdes marginal basin preserved in the Larsen Harbour complex on South Georgia yield the first clear evidence that Gondwanaland fragmentation had resulted in the formation of oceanic crust in the Weddell Sea region by the Late Jurassic (150 ± 1 Ma). The geographic pattern in the observed age range of 8 to 13 million years in these ophiolitic materials, while not definitive, is in keeping with propagation of the marginal basin floor northwestward from South Georgia Island to the Sarmiento Complex in southern Chile. Rocks of the Beagle granite suite, emplaced post-tectonically within the uplifted marginal basin floor, have complex zircon U-Pb systematics with gross discordances dominated by inheritances in some samples and Pb loss in others. Of eleven samples processed, only two had sufficient amounts of zircon for

  19. Prediction of extreme floods in the Central Andes by means of Complex Networks

    Science.gov (United States)

    Boers, Niklas; Bookhagen, Bodo; Barbosa, Henrique; Marwan, Norbert; Kurths, Jürgen; Marengo, Jose

    2014-05-01

    Based on a non-linear synchronisation measure and complex network theory, we present a novel framework for the prediction of extreme events of spatially embedded, interrelated time series. This method is general in the sense that it can be applied to any type of spatially sampled time series with significant interrelations, ranging from climate observables to biological or stock market data. In this presentation, we apply our method to extreme rainfall in South America and show how this leads to the prediction of more than 60% (90% during El Niño conditions) of extreme rainfall events in the eastern Central Andes of Bolivia and northern Argentina, with only 1% false alarms. From paleoclimatic to decadal time scales, the Central Andes continue to be subject to pronounced changes in climatic conditions. In particular, our and past work shows that frequency as well as magnitudes of extreme rainfall events have increased significantly during past decades, calling for a better understanding of the involved climatic mechanisms. Due to their large spatial extend and occurrence at high elevations, these extreme events often lead to severe floods and landslides with disastrous socioeconomic impacts. They regularly affect tens of thousands of people and produce estimated costs of the order of several hundred million USD. Alongside with the societal value of predicting natural hazards, our study provides insights into the responsible climatic features and suggests interactions between Rossby waves in polar regions and large scale (sub-)tropical moisture transport as a driver of subseasonal variability of the South American monsoon system. Predictable extreme events result from the propagation of extreme rainfall from the region of Buenos Aires towards the Central Andes given characteristic atmospheric conditions. Our results indicate that the role of frontal systems originating from Rossby waves in polar latitudes is much more dominant for controlling extreme rainfall in

  20. Surface Uplift History of the Central Andes: Implications for the Growth of Orogenic Plateaus

    Science.gov (United States)

    Garzione, C. N.; Hoke, G. D.; Libarkin, J. C.; MacFadden, B. J.; Withers, S.

    2007-05-01

    Sedimentation, paleoelevation, and incision histories provide important constraints on the timing and magnitude of regional surface uplift of mountain belts that point to specific processes that led to surface uplift. The sedimentary record and stable isotopic compositions of carbonates are used to reconstruct the late Miocene subsidence history, paleoenvironment, and paleoelevation of the northern Altiplano basin. Multiple paleoelevation proxies, including paleoleaf physiognomy, δ18O paleoaltimetry, and Δ47 paleothermometry, suggest that the Altiplano rose by 2.5±0.5 km to 3.5±0.5 km to its current elevation between ~10 and 7 Ma. Geomorphic evidence from widespread, low-relief paleosurfaces on both the eastern and western flanks of the Andes also shows that the onset of rapid incision of paleosurfaces occurred between ~10 and 6.5 Ma over the entire width of the mountain belt and over at least 5° latitude. Stream profile analysis of the drainage systems that incise these paleosurfaces has been inferred to reflect ~1 to 2 km of surface uplift of the flanks of the Andes. Combining geomorphic evidence with paleoelevation constraints, the paleotopographic evolution of the Andes is reconstructed over the late Miocene. Late Miocene regional surface uplift requires the removal of mantle lithosphere as the dominant geodynamic mechanism for raising the plateau during this time. However, crustal thickening and redistribution of crust by erosion/sedimentation and/or lower crustal flow set the limit of surface uplift. Regional surface uplift of the Andean plateau in the late Miocene predicts a decrease in the horizontal deviatoric stress in the plateau that is consistent with observations of upper crustal shortening, sedimentation rates, and magmatism in the plateau. Shortening ceased across the plateau between 10 and 7 Ma, coincident with widespread ignimbrite eruptions and an abrupt decrease in sedimentation rates. The combination of geodynamic processes that appear to

  1. Quantitative Temperature Reconstructions from Holocene and Late Glacial Lake Sediments in the Tropical Andes using Chironomidae (non-biting midges)

    Science.gov (United States)

    Matthews-Bird, F.; Gosling, W. D.; Brooks, S. J.; Montoya, E.; Coe, A. L.

    2014-12-01

    Chironomidae (non-biting midges) is a family of two-winged aquatic insects of the order Diptera. They are globally distributed and one of the most diverse families within aquatic ecosystems. The insects are stenotopic, and the rapid turnover of species and their ability to colonise quickly favourable habitats means chironomids are extremely sensitive to environmental change, notably temperature. Through the development of quantitative temperature inference models chironomids have become important palaeoecological tools. Proxies capable of generating independent estimates of past climate are crucial to disentangling climate signals and ecosystem response in the palaeoecological record. This project has developed the first modern environmental calibration data set in order to use chironomids from the Tropical Andes as quantitative climate proxies. Using surface sediments from c. 60 lakes from Bolivia, Peru and Ecuador we have developed an inference model capable of reconstructing temperatures, with a prediction error of 1-2°C, from fossil assemblages. Here we present the first Lateglacial and Holocene chironomid-inferred temperature reconstructions from two sites in the tropical Andes. The first record, from a high elevation (4153 m asl) lake in the Bolivian Andes, shows persistently cool temperatures for the past 15 kyr, punctuated by warm episodes in the early Holocene (9-10 kyr BP). The chironomid-inferred Holocene temperature trends from a lake sediment record on the eastern Andean flank of Ecuador (1248 m asl) spanning the last 5 millennia are synchronous with temperature changes in the NGRIP ice core record. The temperature estimates suggest along the eastern flank of the Andes, at lower latitudes (~1°S), climate closely resemble the well-established fluctuations of the Northern Hemisphere for this time period. Late-glacial climate fluctuations across South America are still disputed with some palaeoecological records suggesting evidence for Younger Dryas

  2. An improved conceptual understanding of snowmelt and groundwater dynamics in the semi-arid Andes

    Science.gov (United States)

    Sproles, Eric; Hevia, Andres; Soulsby, Chris; Tetzlaff, Doerthe

    2016-04-01

    The contribution of snowmelt to groundwater has long been recognized as an important component of the hydrological cycle in semi-arid northern central Chile (29°-32°S). Despite its importance as a water resource, this transition to groundwater remains poorly understood. Climatically, the High Cordillera in northern central Chile receives approximately 10 times as much annual precipitation as the valley bottoms, falling almost exclusively as snow above 3500 m during the winter months. Geologically, the High Cordillera is characterized by steep topography and a highly dissected landscape underlain by bedrock. Groundwater stores in the mountain headwaters are assumed to be constrained to the valley bottoms. The current working hypothesis of watershed processes in the High Cordillera describes fluxes of spring melt moving through the hillslope via local flowpaths to valley aquifers that recharge streams throughout the headwater reaches. Previous studies in the region indicate Pre-Cordilleran aquifers, located in lower elevation dry ephemeral valleys, are hydrologically disconnected from the High Cordillera. These watersheds have no seasonal snowpack, and recharge occurs primarily during infrequent rain events. These isolated Pre-Cordilleran aquifers serve as an important water resource for rural residents and infrastructure. We present stable isotope, geochemical, and groundwater level data from the wet El Niño winter of 2015 that suggests a topographically disconnected aquifer in the Pre-Cordillera received considerable recharge from High Cordillera snowmelt. These novel findings are indicative of deep groundwater flow paths between the Pre- and High Cordillera during the wet winter and spring of 2015, and improve the conceptual understanding of hydrological processes in the region. Additionally, these results will directly benefit groundwater management in the Pre-Cordillera and better inform modeling efforts in the High Cordillera. While this study is limited to

  3. Carbon stabilization mechanisms in soils in the Andes

    Science.gov (United States)

    Jansen, Boris; Cammeraat, Erik

    2015-04-01

    The volcanic ash soils of the Andes contain very large stocks of soil organic matter (SOM) per unit area. Consequently, they constitute significant potential sources or sinks of the greenhouse gas CO2. Climate and/or land use change potentially have a strong effect on these large SOM stocks. To clarify the role of chemical and physical stabilisation mechanisms in volcanic ash soils in the montane tropics, we investigated carbon stocks and stabilization mechanisms in the top- and subsoil along an altitudinal transect in the Ecuadorian Andes. The transect encompassed a sequence of paleosols under forest and grassland (páramo), including a site where vegetation cover changed in the last century. We applied selective extraction techniques, performed X-ray diffraction analyses of the clay fraction and estimated pore size distributions at various depths in the top- and subsoil along the transect. In addition, from several soils the molecular composition of SOM was further characterized with depth in the current soil as well as the entire first and the top of the second paleosol using GC/MS analyses of extractable lipids and Pyrolysis-GC/MS analyses of bulk organic matter. Our results show that organic carbon stocks in the mineral soil under forest a páramo vegetation were roughly twice as large as global averages for volcanic ash soils, regardless of whether the first 30cm, 100cm or 200cm were considered. We found the carbon stabilization mechanisms involved to be: i) direct stabilization of SOM in organo-metallic (Al-OM) complexes; ii) indirect protection of SOM through low soil pH and toxic levels of Al; and iii) physical protection of SOM due to a very high microporosity of the soil (Tonneijck et al., 2010; Jansen et al. 2011). When examining the organic carbon at a molecular level, interestingly we found extensive degradation of lignin in the topsoil while extractable lipids were preferentially preserved in the subsoil (Nierop and Jansen, 2009). Both vegetation

  4. Variabilidad estacional de cadmio en un sistema de surgencia costera del norte de Chile (Bahía Mejillones del Sur, 23° S Seasonal variability of cadmium in a coastal upwelling system off northern Chile (Mejillones bay, 23° S

    Directory of Open Access Journals (Sweden)

    JORGE VALDÉS

    2006-12-01

    Full Text Available Entre junio de 2002 y abril de 2003 se midió el contenido de cadmio total y disuelto entre la superficie y los 100 m de profundidad, en dos estaciones localizadas en la bahía Mejillones del Sur. El rango de cadmio total y cadmio disuelto en las aguas de esta bahía fue 0,41-10,7 y 0,08-1,61 nM, respectivamente, durante el período de muestreo. Los resultados fueron correlacionados con la estructura físico-química de la columna de agua al momento del muestreo, de manera de estudiar los patrones de variabilidad estacional de este metal en este sistema de surgencia. Las condiciones oceanográficas imperantes durante este período correspondieron a un año normal (no-El Niño. Las masas de agua presentes en la bahía correspondieron a agua subantártica, subtropical y ecuatorial subsuperficial, con diferentes grados de mezcla y estratificación durante el período de estudio. Los perfiles de cadmio presentaron una distribución vertical clásica de un micronutriente. Sin embargo estos perfiles presentaron leves diferencias que pueden ser atribuidas a la condición de mezcla de las masas de agua al interior de la bahía. Un análisis multivariado de los parámetros registrados indicó que la variación temporal de cadmio en las aguas superficiales está asociada a las fluctuaciones de la clorofila a y la temperatura. Esto sugiere que, a escala estacional, la producción de biomasa fitoplanctónica sería el principal factor que controla la distribución de cadmio en esta bahía. Por otro lado, a pesar de que el cadmio es un metal redox sensitivo no se encontró un efecto significativo de la disponibilidad de oxígeno sobre el comportamiento de este metal, de manera que la condición micróxica de las aguas de fondo de la bahía no sería un factor preponderante en el flujo de cadmio hacia los sedimentos. La razón Cd/PO4 encontrada en Mejillones es similar a la reportada en otras zonas costeras de Chile. Los bajos valores y la tendencia temporal

  5. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1983

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1983 calendar year. The report...

  6. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1981

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1981 calendar year. The report...

  7. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1982

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1982 calendar year. The report...

  8. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1984

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1984 calendar year. The report...

  9. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1985

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1985 calendar year. The report...

  10. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1989

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1989 calendar year. The report...

  11. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1986

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1986 calendar year. The report...

  12. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1988

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1988 calendar year. The report...

  13. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1987

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1987 calendar year. The report...

  14. Lake Andes National Wildlife Refuge : Annual narrative report : Calendar year 1992

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1992 calendar year. The report begins...

  15. Lake Andes National Wildlife Refuge Complex : Annual narrative report : Calendar year 1993

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1993 calendar year. The report begins...

  16. Lake Andes National Wildlife Refuge Complex : Annual narrative report : Calendar year 1991

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Karl Mundt NWR, and Lake Andes WMD outlines Refuge accomplishments during the 1991 calendar year. The report begins...

  17. Lake Andes National Wildlife Refuge: Annual narrative report: Calendar year 1990

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Lake Andes NWR, Lake Andes WMD, and Karl E. Mundt NWR outlines Refuge accomplishments during the 1990 calendar year. The report...

  18. A satellite geodetic survey of large-scale deformation of volcanic centres in the central Andes

    Science.gov (United States)

    Pritchard, Matthew E.; Simons, Mark

    2002-07-01

    Surface deformation in volcanic areas usually indicates movement of magma or hydrothermal fluids at depth. Stratovolcanoes tend to exhibit a complex relationship between deformation and eruptive behaviour. The characteristically long time spans between such eruptions requires a long time series of observations to determine whether deformation without an eruption is common at a given edifice. Such studies, however, are logistically difficult to carry out in most volcanic arcs, as these tend to be remote regions with large numbers of volcanoes (hundreds to even thousands). Here we present a satellite-based interferometric synthetic aperture radar (InSAR) survey of the remote central Andes volcanic arc, a region formed by subduction of the Nazca oceanic plate beneath continental South America. Spanning the years 1992 to 2000, our survey reveals the background level of activity of about 900 volcanoes, 50 of which have been classified as potentially active. We find four centres of broad (tens of kilometres wide), roughly axisymmetric surface deformation. None of these centres are at volcanoes currently classified as potentially active, although two lie within about 10km of volcanoes with known activity. Source depths inferred from the patterns of deformation lie between 5 and 17km. In contrast to the four new sources found, we do not observe any deformation associated with recent eruptions of Lascar, Chile.

  19. A satellite geodetic survey of large-scale deformation of volcanic centres in the central Andes.

    Science.gov (United States)

    Pritchard, Matthew E; Simons, Mark

    2002-07-11

    Surface deformation in volcanic areas usually indicates movement of magma or hydrothermal fluids at depth. Stratovolcanoes tend to exhibit a complex relationship between deformation and eruptive behaviour. The characteristically long time spans between such eruptions requires a long time series of observations to determine whether deformation without an eruption is common at a given edifice. Such studies, however, are logistically difficult to carry out in most volcanic arcs, as these tend to be remote regions with large numbers of volcanoes (hundreds to even thousands). Here we present a satellite-based interferometric synthetic aperture radar (InSAR) survey of the remote central Andes volcanic arc, a region formed by subduction of the Nazca oceanic plate beneath continental South America. Spanning the years 1992 to 2000, our survey reveals the background level of activity of about 900 volcanoes, 50 of which have been classified as potentially active. We find four centres of broad (tens of kilometres wide), roughly axisymmetric surface deformation. None of these centres are at volcanoes currently classified as potentially active, although two lie within about 10 km of volcanoes with known activity. Source depths inferred from the patterns of deformation lie between 5 and 17 km. In contrast to the four new sources found, we do not observe any deformation associated with recent eruptions of Lascar, Chile. PMID:12110886

  20. Genesis of adakite-like lavas of Licancabur volcano (Chile—Bolivia, Central Andes)

    Science.gov (United States)

    Figueroa, Oscar; Déruelle, Bernard; Demaiffe, Daniel

    2009-04-01

    The Licancabur volcano is located on the Bolivia—Chile Altiplano (Central Andes). The lavas are andesites and dacites. Numerous mineralogic features attest that magma mixing occurred. Andesites have concave (spoon-shaped) REE patterns whereas dacites have steep slopes. A spectacular crossover of patterns occurs with increasing SiO 2. Most geochemical discrimination criteria of adakites are satisfied by Licancabur dacites, except their high Sr-isotope compositions (> 0.7075). For the genesis of the Licancabur adakite-like lavas, a four-step model is proposed: (1) partial melting (5 to 10 wt %) of a subducted altered oceanic crust; (2) hybridation (< 10 wt %) of the magmas with melts derived from the overlying lithospheric mantle; (3) contamination (≈ 1 wt %) of these hybrid magmas by TTG-type granodiorites of the Archean lower continental crust (with present-day Sr-isotope ratios ≈ 0.820); (4) evolution and differentiation by crystal fractionation (< 6 wt %) and magma mixing at upper crustal levels.

  1. The fruit fly programme in Chile

    International Nuclear Information System (INIS)

    Full text: country. In fact, no species of the genera Ceratitis, Bactrocera, Anastrepha, Dacus and Toxotrypana exist in the country. This programme uses the Fruit fly National Detection System, which includes detection of the pest by trapping and fruit sampling in different areas located between the I and XI Regions of the country. This system is approved by the Chilean trade partners on the basis of the fruit fly-free recognition. For the Chilean fresh fruit exports, this is an important advantage, because there is no need to apply quarantine treatments or any other restriction measure. Chile has also a huge fruit industry, whose export revenues last season reached USD 1,900 million. This fact has permitted to undertake continuously a big effort to maintain that phytosanitary condition. Since Chile is the only fruit-fly free Latin American country, it has to face a continuous biological pressure of fruit flies, mainly C. capitata, to invade its territory. But the country has also some important advantages to prevent flies migrating due to its natural isolation. These natural barriers are the Los Andes ranges in the east, thousands of kilometers of desert in the north, the Pacific Ocean in the west and finally an extremely cold, sub polar climate in the south. This isolation has led to the NPPO officials to believe that the passive spread, through smuggling and hidden fruit in passenger's baggage, to be the most likely source of fruit fly entries. Because of that, Chile has a very strict quarantine system with border control stations at every point of entry. The only exception to the mentioned isolation is Arica Province on the border with Peru. There, SAG applies an area-wide preventative approach through the rearing and release of sterile insects, as well as bait spraying in the border area, which is mainly desert, but has some 'green spots' that allow the fly to alight for resting and feeding. Additionally, through bi-national agreements, common activities are

  2. Reverse Faulting as a Crucial Mechanism for Magma Ascent in Compressional Volcanic Arcs: Field Examples from the Central Andes

    Science.gov (United States)

    Aron, F. A.; Gonzalez, G.; Cembrano, J. M.; Veloso, E. E.

    2010-12-01

    The nature of crustal deformation in active arcs and the feedback mechanisms between tectonics and magma transport constitute fundamental problems in the understanding of volcanic systems. Additionally, for geothermal energy exploration, a better understanding of how crustal architecture and stress field controls fluid ascent and heat transfer from deep levels to the surface is crucial. The Central Andes volcanic belt is an excellent, modern example of such systems but, the scarcity of good outcrops has limited our ability to define the relations between structure and volcanism. In the Salar de Atacama Basin of northern Chile, there are good exposures of folded and faulted Neogene units (continental sediments, volcanic rocks and ignimbrites) and reverse faults spatially and temporally related to volcanic edifices. The subsurface of the study area has been interpreted by previous authors as a thin-skinned, 6-8 km-deep, east-vergent compressional belt. We carried out structural mapping, Digital Elevation Models (DEMs) analyses, strain tensor analyses and fault-related fold kinematic modelling to assess the causal relationship between compressional deformation and magmatism in this region. Field observations indicate that the structures deformed progressively Oligocene-Miocene continental sedimentary units, the upper sedimentary infill of the Salar de Atacama basin (Pliocene-Present), and Pliocene-Pleistocene Ignimbrites. The topographic expression of the compressional belt corresponds to a set of subparallel, asymmetric, fault-related-folds, which can be seen in the field as prominent NS-trending ridges with heights ranging between 50 and 400 m. Furthermore, we found evidence of a ~100 km-long structure along the active magmatic arc, so-called Miscanti Fault. This fault represents the easternmost expression of the above mentioned compressional belt. Pleistocene-Holocene monogenetic cones and strato-volcanoes are located either at the hinge zone of fault

  3. complejidad en Chile

    Directory of Open Access Journals (Sweden)

    Miguel Alejandro Bustamante-Ubilla

    2015-01-01

    Full Text Available El presente estudio tiene por objetivo caracterizar el clima organizacional al interior de 2 hospitales dealta complejidad de Chile, determinando las dimensiones más y menos influyentes. Para su desarrollose aplicó un cuestionario que consta de 71 variables agrupadas en 14 dimensiones a una muestra de561 funcionarios. La interpretación de los resultados se realizó a través del análisis del valor prome-dio estandarizado y su confiabilidad ratificada mediante el alfa de Cronbach. A partir de lo anterior, sedeterminó que las dimensiones que influyen por encima del promedio fueron: identidad, motivaciónlaboral y responsabilidad; en tanto que las dimensiones que muestran un nivel de impacto por debajodel promedio resultaron ser: equipo y distribución de personas y material, administración del conflictoy comunicación.© 2015 Universidad ICESI. Publicado por Elsevier España, S.L.U. Este es un artículo Open Access bajo lalicencia CC BY (http://creativecommons.org/licenses/by/4.0/.

  4. Variación fenotípica y genética en el tunicado Pyura praeputialis (Heller, 1878 en el área norte de la Bahía de Antofagasta, Chile Phenotypic and genetic variation in tunicate Pyura praeputialis (Heller, 1878 in the northern sac of the Antofagasta Bay

    Directory of Open Access Journals (Sweden)

    MARCELA ASTORGA

    2002-09-01

    localities in the northern sac of the Bay of Antofagasta, Chile, and distributed along a wave exposure gradient. A total of 17 enzymatic loci were assayed by horizontal starch-gel electrophoresis, three of which (IDH-1, MDH-1 and PGM-1 were polymorphic. The results showed significant genetic differences among localities, but not among morphotypes. These results are contrasted with similar studies conducted on the same species in Australia, on the base that P. praeputialis has recently colonized Antofagasta from Australia. It is suggested that the differences among the morphotypes from Antofagasta are intraspecifics and those from Australia are interspecifics. The possible explanations for the genetic and morphological differences among localities are discussed

  5. PARASITOS DE LOS ANIMALES DOMESTICOS EN CHILE

    OpenAIRE

    HECTOR ALCAINO; TEXIA GORMAN

    1999-01-01

    PARASITES OF DOMESTIC ANIMALS IN CHILE An up-to-date list of the parasites that have been identified in horses, cattle, sheep, goats, llamas, alpacas, pigs, dogs, cats, rabbits, chickens and pigeons in Chile, according to the studies performed at the University of Chile and other Universities and Institutes.

  6. China and Chile Signing Free Trade Agreement

    Institute of Scientific and Technical Information of China (English)

    Shen; Danyang

    2005-01-01

      Mr. Bo Xilai, Minister of Commerce of China, and Mr.Walker, Foreign Minister of Chile, signed the China-Chile FTA on behalf of their respective government on November 18, 2005. Chinese President Hu Jintao and Chile President Lagos attended the signing ceremony, according to a press release on the website of Network Center of MOFCOM.……

  7. China and Chile Signing Free Trade Agreement

    Institute of Scientific and Technical Information of China (English)

    Shen Danyang

    2005-01-01

    @@ Mr. Bo Xilai, Minister of Commerce of China, and Mr.Walker, Foreign Minister of Chile, signed the China-Chile FTA on behalf of their respective government on November 18, 2005. Chinese President Hu Jintao and Chile President Lagos attended the signing ceremony, according to a press release on the website of Network Center of MOFCOM.

  8. PARASITOS DE LOS ANIMALES DOMESTICOS EN CHILE

    Directory of Open Access Journals (Sweden)

    HECTOR ALCAINO

    1999-01-01

    Full Text Available PARASITES OF DOMESTIC ANIMALS IN CHILE An up-to-date list of the parasites that have been identified in horses, cattle, sheep, goats, llamas, alpacas, pigs, dogs, cats, rabbits, chickens and pigeons in Chile, according to the studies performed at the University of Chile and other Universities and Institutes.

  9. Contrasting response of glacierized catchments in the Central Himalaya and the Central Andes to climate change

    Science.gov (United States)

    Ragettli, Silvan; Pellicciotti, Francesca; Immerzeel, Walter

    2015-04-01

    The Andes of South America and the Himalaya in high-mountain Asia are two regions where advanced simulation models are of vital importance to anticipate the impacts of climate change on water resources. The two mountain systems hold the largest ice masses outside the polar regions. Major rivers originate here and downstream regions are densely populated. In the long run, glacier recession generates concerns about the sustainability of summer runoff. This study benefits from recent efforts of carefully planned short-term field experiments in two headwater catchments in the Central Andes of Chile and in the Central Himalaya in Nepal. The two study catchments contrast in terms of their climate and in the characteristics of their glaciers. A systematic approach is developed, built upon the available local data, to reduce the predictive uncertainty of a state-of-the-art glacio-hydrological model used for the projection of 21st century glacier changes and catchment runoff. The in-situ data are used for model development and step-wise, multivariate parameter calibration. Catchment runoff and remotely sensed MODIS and Landsat snow cover are used for model validation. The glacio-hydrological model simulates the water cycle with a high temporal (hourly time steps) and spatial (100 m grid cells) resolution and accounts for processes typical of both regions like glacier melt under debris cover or mass redistribution through avalanching. Future projections are based on the outputs of twelve stochastically downscaled global climate models for two emission scenarios (RCP 4.5 and RCP 8.5). This is one of the first truly intercomparative modeling studies at the catchment scale across mountain regions of the world to assess and compare future changes in glaciers and snow cover and associated impacts on streamflow production. Both catchments will experience significant glacier mass loss throughout the twenty-first century. However, the trajectories of simulated future runoff and

  10. The Largest Holocene Eruption of the Central Andes Found

    Science.gov (United States)

    Fernandez-Turiel, J.; Rodriguez-Gonzalez, A.; Saavedra, J.; Perez-Torrado, F.; Carracedo, J.; Osterrieth, M.; Carrizo, J.; Esteban, G.

    2013-12-01

    We present new data and interpretation about a major eruption -spreading ˜110 km3 ashes over 440.000 km2- long thought to have occurred around 4200 years ago in the Cerro Blanco Volcanic Complex (CBVC) in NW Argentina. This eruption may be the biggest during the past five millennia in the Central Volcanic Zone of the Andes, and possibly one of the largest Holocene eruptions in the world. The environmental effects of this voluminous eruption are still noticeable, as evidenced by the high content of arsenic and other trace elements in the groundwaters of the Chacopampean Plain. The recognition of this significant volcanic event may shed new light on interpretations of critical changes observed in the mid-Holocene paleontological and archaeological records, and offers researchers an excellent, extensive regional chronostratigraphic marker for reconstructing mid-Holocene geological history over a wide geographical area of South America. More than 100 ashes were sampled in Argentina, Chile and Uruguay during different field campaigns. Ash samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), grain size distributions laser diffraction, and geochemically by electron microprobe (EMPA) and laser ablation-HR-ICP-MS. New and published 14C ages were calibrated to calendar years BP. The age of the most recent CBVC eruption is 4407-4093 cal y BP, indirectly dated by 14C of associated organic sediment within the lower part of a proximal fall deposit of this event (26°53'16.05"S-67°44'48.68"W). This is the youngest record of a major volcanic event in the Southern Puna. This age is consistent with other radiocarbon dates of organic matter in palaeosols underlying or overlying distal ash fall deposits. Based on their products, all of rhyolitic composition, we have distinguished 8 main episodes during the evolution of the most recent CBVC eruption: 1) the eruption began with a white rhyolite lava dome extrusion; 2) followed by a Plinian

  11. Preliminary Results From the CAUGHT Experiment: Investigation of the North Central Andes Subsurface Using Receiver Functions and Ambient Noise Tomography

    Science.gov (United States)

    Ryan, J. C.; Ward, K. M.; Porter, R. C.; Beck, S. L.; Zandt, G.; Wagner, L. S.; Minaya, E.; Tavera, H.

    2011-12-01

    Altiplano and portions of the Eastern Cordillera, and at approximately 40 under the sub-Andes and westernmost edge of the Beni basin. Unlike previous studies farther south, we do not see an increased crustal thickness beneath the Eastern Cordillera. The CAUGHT station coverage is also ideal for Ambient Noise Tomography (ANT) to investigate the seismic shear wave velocities in the upper crust (McQuarrie, N., Barnes, J., and Ehlers, T.A., 2008, Geometric, kinematic and erosional history of the central Andean Plateau (15-17°S), northern Bolivia: Tectonics, v. 27, TC3007, doi:10.1029/2006TC002054.

  12. Water governance in Chile: Availability, management and climate change

    Science.gov (United States)

    Valdés-Pineda, Rodrigo; Pizarro, Roberto; García-Chevesich, Pablo; Valdés, Juan B.; Olivares, Claudio; Vera, Mauricio; Balocchi, Francisco; Pérez, Felipe; Vallejos, Carlos; Fuentes, Roberto; Abarza, Alejandro; Helwig, Bridget

    2014-11-01

    Chile has a unique geography that provides an extraordinary variety of climatic conditions and availability of water resources. The objective of this manuscript was to describe and analyze the spatial and temporal distribution patterns, as well as the management of water resources, along a country with a narrow distance from the Andes Mountains to the Pacific Ocean. This presents challenges to water governance from data collection and analysis perspectives, and for administration of the resource. The Water Resources Directorate (Dirección General de Aguas, DGA), is the federal government organization in charge of the water resources of the country. The DGA and other relevant public and private institutions are examined in terms of competition and conflict resolution across different scales and levels of interaction associated with water resources governance. Both monitoring stations (rainfall, streamflow, water quality, groundwater, sediment and snowfall), and the Chilean management and legislation of water resources are also analyzed. Finally, the success (or lack) of the national administration to upgrade its monitoring stations and equalize water resources distribution throughout the country is discussed including the influence of climate change on data collection, and decision making across different scales of water governance.

  13. Revisiting the Source Process of the 2007 Tocopilla, Chile Earthquake

    Science.gov (United States)

    Simons, M.; Minson, S. E.; Jolivet, R.; Jiang, J.; Beck, J. L.

    2013-12-01

    We revisit the 2007 Mw 7.7 Tocopilla, Chile earthquake to create a finite fault kinematic source model based on the current best practices in data analysis and inversion methods. The data used to constrain the source model include both static GPS offsets and 1 Hz kinematic GPS time series, as well as interferograms which have been reanalyzed to remove tropospheric effects which can be quite significant in this region. Our inversion methodology is a Bayesian approach that uses only physics-based constraints on the rupture evolution, and which utilizes models of both the observational noise and the errors in our forward model to obtain the ensemble of all plausible rupture models which satisfy both the data and our a priori assumptions. This approach allows us to better understand which parts of the rupture process are well-constrained and which are not, and thus to better understand how the 2007 Tocopilla, Chile earthquake rupture fits into the sequence of large earthquakes which have been mosaicking the northern Chile subduction zone.

  14. Orogenesis at the southern tip of the Americas: the structural evolution of the Cordillera Darwin metamorphic complex, southernmost Chile

    Science.gov (United States)

    Cunningham, W. Dickson

    1995-04-01

    New, detailed lithologic and structural data are presented from three separately mapped areas along the southern boundary of the Cordillera Darwin metamorphic complex of southernmost Chile. Cordillera Darwin is a unique uplift because it exposes the highest grade rocks in the Andes south of Peru and averages 1 km higher in elevation than adjacent areas. The structural data indicate that Cordillera Darwin experienced mid-Late Cretaceous trans-pressional deformation with a partitioned strike-slip component localized along the Beagle Channel that forms the southern boundary to the range. Foliation, lineation and fold axis trends indicate NE-SW-directed contraction and NW-SE strike-slip shearing (present directions) during progressive {D1}/{D2} Andean deformation. D2 deformation is marked by outcrop-to 10 km-scale south-southwest-vergent folds. Late Cretaceous-Tertiary brittle-ductile and brittle left-lateral strike-slip faults and shear zones crosscut all {D1}/{D2} structures. Although limited structural evidence for extensional tectonics was documented in this study, apparent normal offsets across both arms of the Beagle Channel and previously documented field evidence for extension from other areas in Cordillera Darwin suggest that transtensional displacements also may have occurred in southern Cordillera Darwin during the Late Cretaceous-Early Tertiary. Cordillera Darwin's position within the evolving Patagonian Orocline adjacent to an evolving Mesozoic-Cenozoic left-lateral transform boundary between the South American and Antarctic plates, and later the South American and Scotia plates, necessitates consideration of the possible effects of regional counterclockwise rotation on development of structures. Regional counterclockwise rotation of Cordillera Darwin may have controlled the temporal and spatial transition of deformational regimes within Cordillera Darwin. Exhumation of the metamorphic core of Cordillera Darwin during the Late Cretaceous-Early Tertiary is

  15. First records of Eocr Onartium muscicola (Basidiomycota, Eocronartiaceae) in Chile on two new hosts Primeros registros de Eocronartium muscicola (Basidiomycota, Eocronartiaceae) en Chile sobre dos nuevos hospederos

    OpenAIRE

    Pablo Sandoval; José L Henríquez; Luis Faúndez; Juan Larraín

    2012-01-01

    The heterobasidiomycete fungus Eocronartium muscicola is an obligate parasite recorded on about 21 moss species, mainly from the Northern Hemisphere. It interacts with its hosts mainly by replacing the sporophyte and obtaining water and nutrients from the gametophyte through specialized tissues. This work reports for the first time E. muscicola on the native mosses Eurhynchium corralense and Eurhynchiella acanthophylla in central and southern Chile, in different forest formations. Also, assoc...

  16. The biomethane potential in Chile

    International Nuclear Information System (INIS)

    Within the last decade natural gas gained considerable importance in Chile. The contribution of natural gas within the energy system will increase in the future by predicted 3.6% annually until the year 2015. Due to limited resources within its own country, the energy system of Chile depends on natural gas imports preferential from Argentina. Therefore, the aim of several stakeholders from policy and industry is to reduce the share of imported primary energy within the overall energy system. In order to reach this goal, the use of domestic resources and particularly the utilisation of biomass as one of the most important renewable sources of energy in Chile could play an important role. Against this background, the goal of this paper is the analysis of the technical potentials of biomethane as a substitute for natural gas. For the production of biomethane the anaerobic or bio-chemical (i.e. Biogas) as well as the thermo-chemical conversion pathways (i.e. Bio-SNG) are considered. The results of this analysis show that biomass converted to biomethane is a promising energy provision option for Chile and it contributes to the reduction of greenhouse gas emissions

  17. Corporate Governance Country Assessment : Chile

    OpenAIRE

    World Bank

    2003-01-01

    Chile's equity market is fairly large and successful. The market capitalization of the 249 listed firms represented 89 percent of GDP at year-end, 2001. Corporate ownership is concentrated and pyramid structures are common. Business groups/conglomerates are the predominant corporate form. Institutional investors, especially pension funds, are active equity investors. The Securities Market ...

  18. Socialisme i Chile efter Pinochet

    DEFF Research Database (Denmark)

    Cristoffanini, Pablo Rolando

    2008-01-01

    Chile bliver ofte præsenteret som et paradigme for resten af det latinamerikanske kontinent: Et land med høj økonomisk vækst og politisk stabilitet. Landet har endda haft to socialistiske præsidenter siden 2000, den sidste den første kvindelige præsident. Succeshistorien har en bagside: De social...

  19. A study of stratospheric GW fluctuations and sporadic E at midlatitudes with focus on possible orographic effect of Andes

    Science.gov (United States)

    Hocke, Klemens; Tsuda, Toshitaka; de la Torre, Alejandro

    2002-10-01

    Longitudinal dependences of stratospheric gravity wave (GW) fluctuations and lower ionospheric irregularities (sporadic E) at midlatitudes are studied by means of radio occultation data of the Global Positioning System/Meteorology Experiment (GPS/MET) satellite mission. The zonal average of temperature variance of GW fluctuations with vertical scales less than 7 km at northern midlatitudes is observed to be similar to that at southern midlatitudes, but there is a significant interhemispheric difference in the longitudinal dependence of GW fluctuations. The GPS/MET data at northern midlatitudes show a rapid change of the gravity wave distribution from 25 to 35 km height, resulting in a broad maximum of temperature variance located over the Atlantic and Eurasia. We only find in the wave distribution at h = 25 km some weak traces of possible orographic effects. On the other hand, the distribution of GW fluctuations at southern midlatitudes has a strong and sharp maximum over Andes, which is obviously due to orographic wave generation by the interaction of surface wind with the Andean mountain ridge. This observation of the new GPS radio occultation technique is in agreement with previous measurements of spaceborne microwave and infrared limb sounders. The amplitude of the average wave field increases with height over Andes, while the amplitude maximum moves westward, against the prevailing wind. The temperature fluctuations have an apparent, dominant vertical wavelength of around 6 km. In situ measurements by a balloon-borne rawinsonde at Ushuaia, Argentina (54.7°S, 68.1°W) are compared to a simultaneous GPS/MET temperature profile. The balloon observations of temperature and horizontal wind are interpreted by a large amplitude mountain wave propagating to the upper stratosphere. Wave characteristics and atmospheric background conditions are investigated in detail for this mountain wave observation. Finally, the GPS/MET experiment indicates enhanced sporadic E in

  20. The Continental Distillery: Building Thick Continental Crust in the Central Andes (Invited)

    Science.gov (United States)

    Wagner, L. S.; Beck, S. L.; Zandt, G.; Long, M. D.; Tavera, H.; Minaya, E.; Biryol, C. B.; Bishop, B.; Eakin, C. M.; Franca, G.; Knezevic Antonijevic, S.; Kumar, A.; Ryan, J. C.; Scire, A. C.; Ward, K. M.; Young, B. E.

    2013-12-01

    The formation of stable continental crust and the associated development and destruction of mantle lithospheric roots is central to our understanding of plate tectonics, both at its inception and as an ongoing process today. Subduction zones play an important role in the creation and refinement of continental crust, and also serve as a possible mechanism for the removal of residual mantle material. The central Andes provide an intriguing laboratory for the study of these processes. Up to 400 km wide, 1500 km long, and with an average elevation of 4 km, the Altiplano Plateau is the largest orogen on earth associated with an ocean-continent subduction zone. This is much larger than adjacent 'normal' sections of the Andes, raising the question of why this portion of South American crust became so much more substantial than surrounding areas. Over the past several years, new seismic data have made it possible for us to develop a more complete picture of the lithospheric and asthenospheric processes involved in the development of the Altiplano Plateau and the adjacent narrower orogen further to the north. The 'Central Andean Uplift and the Geodynamics of High Topography' (CAUGHT) comprises in part a broadband deployment of 50 stations across the northern flank of the Altiplano Plateau in southern Peru and northern Bolivia. The adjacent 'PerU Lithosphere and Slab Experiment' (PULSE) includes 40 broadband stations that cover the region directly north of the CAUGHT deployment, encompassing the northern edge of the Altiplano, the transition to 'normal' width orogen, and the transition in slab geometry from normal to flat from south to north across the study area. Uplift of the Altiplano Plateau is likely due to some combination shortening, isostasy due to lithospheric destruction or changes in crustal density, magmatic addition to the crust, and/or flow within the thickened crust. Our studies indicate pervasive low velocities across the Altiplano consistent with a