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Sample records for andes northern chile

  1. 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

  2. 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.

  3. Wide-Angle Seismic Experiment Across the Oeste Fault Zone, Central Andes, Northern Chile.

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    Lorenzo, J. M.; Yáñez, G. A.; Vera, E. E.; Sepúlveda, J.

    2008-12-01

    From December 6-21, 2007, we conducted a 3-component, radio-telemetric, seismic survey along a ~ 15-km wide E-W transect in the Central Andes, at a latitude of ~ 22.41° S, centered north of the city of Calama (68.9° W), Chile. The study area is sandwiched between the Central Depression in the west and the Andean Western Cordillera of Chile. Recording stations, nominally spaced at intervals of either 125 or 250 m collected up to 3.5 s of refracted seismic arrivals at maximum source-receiver offsets exceeding 15 km. Ten shothole sources, spaced 2-6 km apart focused energy on the shallow (0-3 km), crustal, Paleogene-age structures. Preliminary, tomographic inversions of refracted first arrivals show the top of a shallow ( 600 km), strike-slip fault zone known as the Oeste fault. Turning ray densities suggest the base of the overlying velocity gradient unit (VP, 2-4 km/s) dips inwardly from both east and west directions toward the Oeste fault to depths of almost 1 km. Plate reorganization commencing at least by the latter half of the Oligocene led from oblique to more orthogonal convergence between the South American and the Nazca (Farallon) Plates. We interpret previously mapped, older, minor faults as being generated within the right-lateral, orogen-parallel, Oeste strike-slip fault zone, and postdated by Neogene, N-S striking thrust faults. In this context we also interpret that the spatial distribution of velocity units requires an period of extensional activity that may (1) postdate the transpressional strike slip fault activity of the Neogene, (2) be related to a later releasing bend through the translation and interaction of rigid blocks hidden at depth or even (3) be the consequence of inelastic failure from the result of flexural loading.

  4. Paleomagnetism in the Precordillera of northern Chile (22°30'S): implications for the history of tectonic rotations in the Central Andes

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    Somoza, Rubén; Tomlinson, Andrew

    2002-01-01

    Widespread clockwise rotations in Mesozoic and Lower Tertiary rocks of northern Chile have been interpreted as the sum of two rotational events separated in time: an early rotation related to local deformation plus a late rotation related to wholesale rotation of northern Chile linked to Late Cenozoic oroclinal bending in the Central Andes. In this paper we report new paleomagnetic data from Cretaceous, upper Oligocene and Miocene sedimentary rocks in the Precordillera of northern Chile. The results suggest that all these rocks acquired their remanence at or close to the time of deposition. The lack of rotation in undeformed lower Miocene strata clearly indicates that clockwise rotations found in underlying, faulted and folded Cretaceous rocks were completed before the Late Cenozoic. Results from nearby localities in deformed upper Oligocene strata would argue for little (˜5°) rotation since the late Oligocene. Data from widely separated Miocene localities covering an area of about 5000 km 2 in the Calama basin strongly suggest that northern Chile did not undergo significant wholesale rotation during the Late Cenozoic. This, together with previous paleomagnetic evidence against Neogene rigid-body-like rotation of the southern Peruvian forearc, suggests that the curved shape of the Central Andean forearc was not significantly enhanced during the Late Cenozoic. By inference, all of the rotation in most Mesozoic and Lower Tertiary rocks of northern Chile was accomplished in the Cretaceous and/or Early Cenozoic, when the locus of deformation in the Central Andes was localized in the present forearc region.

  5. The role of the Antofagasta-Calama Lineament in ore deposit deformation in the Andes of northern Chile

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    Palacios, Carlos; Ramírez, Luis E.; Townley, Brian; Solari, Marcelo; Guerra, Nelson

    2007-02-01

    During the Late Jurassic-Early Oligocene interval, widespread hydrothermal copper mineralization events occurred in association with the geological evolution of the southern segment of the central Andes, giving rise to four NS-trending metallogenic belts of eastward-decreasing age: Late Jurassic, Early Cretaceous, Late Paleocene-Early Eocene, and Late Eocene-Early Oligocene. The Antofagasta-Calama Lineament (ACL) consists of an important dextral strike-slip NE-trending fault system. Deformation along the ACL system is evidenced by a right-lateral displacement of the Late Paleocene-Early Eocene metallogenic belts. Furthermore, clockwise rotation of the Early Cretaceous Mantos Blancos copper deposit and the Late Paleocene Lomas Bayas porphyry copper occurred. In the Late Eocene-Early Oligocene metallogenic belt, a sigmoidal deflection and a clockwise rotation is observed in the ACL. The ACL is thought to have controlled the emplacement of Early Oligocene porphyry copper deposits (34-37 Ma; Toki, Genoveva, Quetena, and Opache), whereas it deflected the Late Eocene porphyry copper belt (41-44 Ma; Esperanza, Telégrafo, Centinela, and Polo Sur ore deposits). These observations suggest that right-lateral displacement of the ACL was active during the Early Oligocene. We propose that the described structural features need to be considered in future exploration programs within this extensively gravel-covered region of northern Chile.

  6. 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.

  7. Combining numerical modeling and stable isotope values to quantify groundwater recharge from the Chilean Andes to the Pampa del Tamarugal Basin, Atacama Desert, northern Chile

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    Dodd, J. P.; Pollyea, R.

    2014-12-01

    The Atacama Desert of northern Chile is one of the driest regions on Earth and receives less than 5mm of precipitation annually. The Pampa del Tamarugal (PdT) Basin contains the largest aquifer system in the region, yet the mechanisms and timing of aquifer recharge and continental-scale groundwater flux are poorly understood. Although there is little debate that the source of groundwater recharge is the higher elevation regions of the Andean Altiplano to the east of the PdT Basin, there remains much uncertainty surrounding the mechanisms and timing of aquifer recharge and continental-scale groundwater flux. Most recharge models of the PdT focus on surface water runoff and alluvial fan recharge on shorter time scales, but many of these models explicitly neglect deep flow pathways. Previous investigators have combined the thermal aquifer profile and 14C groundwater ages to propose an alternative conceptual model in which cold meteoric water infiltrates deep into the Cordillera before circulating upward into the PdT by thermal convection through fault-controlled migration pathways. Although this conceptual model provides a convincing theoretical argument for deep fluid circulation, it cannot constrain the magnitude of this deep recharge flux. In this work, we revisit deep-flow conceptual model by combining the spatial distribution of hydrogen and oxygen isotope values as groundwater tracers with a non-isothermal model of continental scale groundwater flow through a two-dimensional transect from the Chilean Andes to the PdT Basin. This work provides first-order estimates on the contribution of deep groundwater circulation within the PdT Aquifer, while providing a framework for (1) quantifying boundary conditions for high resolution models of groundwater resources within the PdT Aquifer, (2) assessing the influence of variable future climate scenarios for groundwater availability in the region, and (3) further integrating conservative tracers and numerical models for

  8. Cenozoic uplift of the Central Andes in northern Chile and Bolivia - reconciling paleoaltimetry with the geological evolution.

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    Lamb, S. H.

    2015-12-01

    The Cenozoic geological evolution of the Central Andes, along two transects between ~17.5°S and 21°S, is compared with paleo-topography, determined from published paleo-altimetry studies. Surface and rock uplift are quantified using simple 2-D models of crustal shortening and thickening, together with estimates of sedimentation, erosion and magmatic addition. Prior to ~25 Ma, during a phase of amagmatic flat-slab subduction, thick skinned crustal shortening and thickening was focused in the Eastern and Western Cordilleras, separated by a broad basin up to 300 km wide and close to sea level, which today comprises the high Altiplano. Surface topography in the Eastern Cordillera appears to be ~1 km lower than anticipated from crustal thickening, which may be due to the pull-down effect of the subducted slab, coupled to the overlying lithosphere by a cold mantle wedge. Oligocene steepening of the subducted slab is indicated by the initiation of the volcanic arc at ~27 - 25 Ma, and widespread mafic volcanism in the Altiplano between 25 and 20 Ma. This may have resulted in detachment of mantle lithosphere and possibly dense lower crust, triggering 1 - 1.5 km of rapid uplift (over Altiplano and western margin of the Eastern Cordillera and establishing the present day lithospheric structure beneath the high Andes. Since ~25 Ma, surface uplift has been the direct result of crustal shortening and thickening, locally modified by the effects of erosion, sedimentation and magmatic addition from the mantle. The rate of crustal shortening and thickening varies with location and time, with two episodes of rapid shortening in the Altiplano, lasting < 5 Myrs, that are superimposed on a long term history of ductile shortening in the lower crust, driven by underthrusting of the Brazilian Shield on the eastern margin.

  9. The Amazon-Laurentian connection as viewed from the Middle Proterozoic rocks in the central Andes, western Bolivia and northern Chile

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    Tosdal, R.M.

    1996-01-01

    Middle Proterozoic rocks underlying the Andes in western Bolivia, western Argentina, and northern Chile and Early Proterozoic rocks of the Arequipa massif in southern Peru?? from the Arequipa-Antofalla craton. These rocks are discontinuously exposed beneath Mesozoic and Cenozoic rocks, but abundant crystalline clasts in Tertiary sedimentary rocks in the western altiplano allow indirect samples of the craton. Near Berenguela, western Bolivia, the Oligocene and Miocene Mauri Formation contains boulders of granodiorite augen gneiss (1171??20 Ma and 1158??12 Ma; U-Pb zircon), quartzose gneiss and granofels that are inferred to have arkosic protoliths (1100 Ma source region; U-Pb zircon), quartzofeldspathic and mafic orthogneisses that have amphibolite- and granulite-facies metamorphic mineral assemblages (???1080 Ma metamorphism; U-Pb zircon), and undeformed granitic rocks of Phanerozoic(?) age. The Middle Proterozoic crystalline rocks from Berenguela and elsewhere in western Bolivia and from the Middle Proterozoic Bele??n Schist in northern Chile generally have present-day low 206Pb/204Pb ( 15.57), and elevated 208Pb/204Pb (37.2 to 50.7) indicative of high time-averaged Th/U values. The Middle Proterozoic rocks in general have higher presentday 206Pb/204Pb values than those of the Early Proterozoic rocks of the Arequipa massif (206Pb/204Pb between 16.1 and 17.1) but lower than rocks of the southern Arequipa-Antofalla craton (206Pb/204Pb> 18.5), a difference inferred to reflect Grenvillian granulite metamorphism. The Pb isotopic compositions for the various Proterozoic rocks lie on common Pb isotopic growth curves, implying that Pb incorporated in rocks composing the Arequipa-Antofalla craton was extracted from a similar evolving Pb isotopic reservoir. Evidently, the craton has been a coherent terrane since the Middle Proterozoic. Moreover, the Pb isotopic compositions for the Arequipa-Antofalla craton overlap those of the Amazon craton, thereby supporting a link

  10. 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

  11. 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

  12. Geological development and mineralization in the Atacama segment of the South American Andes, northern Chile (26°15' 27°25'S)

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    Palacios, Carlos M.; Townley, Brian C.; Lahsen, Alfredo A.; Egaña, Antonio M.

    1993-12-01

    Between the Late Jurassic and the Middle Miocene, widespread magmatism, tectonic events and hydrothermal mineralization characterized the geological evolution of the Atacama segment of the South American Andes. A characteristic feature of this zone is the coincidence in time and space between subduction-generated igneous activity, crustal deformation and mineralization in the magmatic arcs, which formed longitudinal belts migrating eastward. Mineralization in the last 140 Ma is generally restricted to four longitudinal metallogenic belts, in which hydrothermal activity was channelled along crustal-scale faults (1) the Atacama Fault System, along which Early Cretaceous Cu-Au-bearing breccia pipes, veins and stockwork were formed; (2) the Inca do Oro Belt, which contains Upper Cretaceous low sulphur precious metal epithermal mineralization, and Middle Eocene Cu-Mo-Au-bearing breccia pipes; (3) the West Fissure System, which hosts Upper Eocene to Early Oligocene porphyry copper deposits and high sulphur precious metal epithermal mineralization; and (4) the Maricunga Belt, when contains Upper Oligocene to Middle Miocene high sulphur precious metal epithermal deposits and Au-rich porphyry mineralization.

  13. Seismological Parameters in the Northern Andes, Venezuela

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    Sobiesiak, M.; Palme de Osechas, C.; Choy, J. E.; Morandi S., M. T.; Campo, M.; Granado Ruiz, C.

    2001-12-01

    Venezuelas tectonic setting as part of the plate boundary between the Caribbean and the South American plate causes two major seismologically active fault systems: the roughly west - east trending strike slip fault system along the coast with numerous sub-parallel faults and the Bocono fault system, which dominates the Venezuelan southwest - northeast striking Andes. The main Bocono fault reaches a total length of about 500 km and has a width of approximately 100 km between the southern and northern baseline of the mountain slopes which are marked by inverse faults. This is believed to be due to strain partitioning, a concept which seems to apply as well to the Bocono fault system. The whole fault system is characterized by a high seismicity rate of small scale and intermediate event magnitudes ranging from 1.5 to 6.3 in the last fifty years. In this study we would like to present an investigation on 39 focal mechanism solutions and a b-value mapping of the Andean region with the main goal to throw light on the stess and strain situation. For recompiling the focal memchanisms calculated from first motion polarities, various sources had to been used: seismograms from stations of the local and regional networks of the Seismological Center of ULA, the national seismic network operated by FUNVISIS, the seismic network Lago Maracaibo of PDVSA and the local seismic network of DESURCA. For the b-value mapping we used the two catalogues of ULA and DESURCA of which the last one registered more than 6500 events from 1994 to 1999. The set of focal mechanism solutions studied showed normal, strike slip, and reverse faulting mechanisms concentrated in distinct areas of the Bocono fault system and thus resulting in a zonation also supported by the determinations of the azimuths of the maximum horizontal stress SHmax. This hypothesis of the zonation of the Andes region is strongly supported by the results of the b-value mapping. The zonation as seen in the varying major stress

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

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    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.)

  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. 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

    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

  17. 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.

  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. [Medical education at Universidad de los Andes, Santiago, Chile].

    Science.gov (United States)

    Orrego Vicuña, F

    1997-07-01

    Universidad de los Andes School of Medicine started in 1991 with a new medical curriculum aimed at providing a medical education for its students, that is, it attempts to give, together with technical proficiency in medical matters, formation of character and a strong ethical attitude. The curriculum lasts for seven years: five of basic, pre-clinical and clinical theoretical and practical courses, followed by two years of internships in Internal Medicine, Surgery, Obstetrics and Pediatrics, plus a four month period of an elective internship. The courses have an integrated design, in which each matter is presented from multiple perspectives, e.g. in Internal Medicine together with the clinical aspects of disease, the pathophysiology and the pharmacology of the drugs used are presented. Also the Pathology of each disease is given in coordination in the Pathology course. General educational matters such as Anthropology, Psychology, Origin of Living Beings, Theology and Medical Ethics are interspersed in the curriculum. An important feature is the personal counselling system, in which each student may choose an academic counsellor and discuss with him (her) the subjects of his choosing. Clinical practice is given in a system that includes five hospitals and five private clinics that range from general medical practice to Psychiatry or Ophthalmology.

  20. Apacheta, a new geothermal prospect in Northern Chile

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  3. Paleomagnetic evidence of earliest Paleocene deformation in Calama (˜22°S), northern Chile: Andean-type or ridge-collision tectonics?

    Science.gov (United States)

    Somoza, R.; Tomlinson, A. J.; Caffe, P. J.; Vilas, J. F.

    2012-08-01

    A paleomagnetic study from the earliest Paleocene Cerros de Montecristo Quartz Monzonite and its Jurassic to uppermost Cretaceous host rock (northern Chile, ˜22°S) provided high-temperature, high-coercivity magnetizations of dominantly reversed polarity. The remanences of the tilted host rock gave a negative fold-test and are indistinguishable from the remanences found in the pluton, indicating that the uppermost Cretaceous rocks underwent deformation before intrusion of the earliest Paleocene pluton, thus documenting a K-T deformation at the locality. Although this deformation may be another product of typical subduction-related noncollisional tectonics in the Central Andes, an alternative hypothesis, permitted by plate reconstructions, is that the event was associated with collision of an oceanic plate boundary. This latter hypothesis may also provide a context for several other tectonic events from northern Chile to the Patagonian Andes, wherein deformation would the consequence of a southward migrating triple junction between the latest Maastrichtian and Early Eocene.

  4. 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 (wave arrivals. Full waveform finite difference modelling is used to test the low velocity slab structure that cause this P-wave dispersion. The synthetic waveforms produced by these models are compared to the recorded waveforms. Spectrograms are used to compare the relative arrival 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

  5. 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.

  6. 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...

  7. Grenvillian remnants in the Northern Andes: Rodinian and Phanerozoic paleogeographic perspectives

    Science.gov (United States)

    Cardona, A.; Chew, D.; Valencia, V. A.; Bayona, G.; Mišković, A.; Ibañez-Mejía, M.

    2010-01-01

    Grenvillian crust is encountered in several basement inliers in the northern Andes of Colombia, Ecuador and Peru and is also represented as a major detrital or inherited component within Neoproterozoic to Paleozoic sedimentary and magmatic rocks. This review of the tectonic and geochronological record of the Grenvillian belt in the northern Andes suggests that these crustal segments probably formed on an active continental margin in which associated arc and back-arc magmatism evolved from ca. 1.25 to 1.16 Ga, possibly extending to as young as 1.08 Ga. The lithostratigraphic and tectonic history of the Grenvillian belt in the northern Andes differs from that of the Sunsas belt on the southwest Amazonian Craton and from the Grenvillian belt of Eastern Laurentia. It is considered that this belt, along with similar terranes of Grenvillian age in Middle America and Mexico define a separate composite orogen which formed on the northwestern margin of the Amazonian Craton. Microcontinent accretion and interaction with the Sveconorwegian province on Baltica is a feasible tectonic scenario, in line with recent paleogeographic reconstructions of the Rodinian supercontinent. Although Phanerozoic tectonics may have redistributed some of these terranes, they are still viewed as para-autocthonous domains that remained in proximity to the margin of Amazonia. Paleogeographic data derived from Phanerozoic rocks suggest that some of the Colombian Grenvillian fragments were connected to northernmost Peru and Ecuador until the Mesozoic, whereas the Mexican terranes where attached to the Colombian margin until Pangea fragmentation in Late Triassic times.

  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

    Directory of Open Access Journals (Sweden)

    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.

  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. 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...

  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. 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.

  16. Temperature and Rainfall Variability in the Northern Andes Over the Past Two Millennia

    Science.gov (United States)

    Shanahan, T. M.; Bixler, C. W.; Mora, A.

    2014-12-01

    Recent studies of tropical glaciers have shown that most are retreating rapidly, with some of the most dramatic changes occurring since the mid-1970s, most likely as a result of increasing global temperatures. However, a longer-term perspective is needed to place these changes in the context of natural climate variability. To better understand the climatological factors driving long-term variations in the mass balance of tropical glaciers, we reconstructed changes in precipitation and temperature in the northern tropical Andes using variations in the hydrogen isotope composition of sedimentary leaf waxes and branched GDGT distributions in a high-resolution varved sediment record from Lago Chingaza, Colombia. Br-GDGT derived temperatures are significantly correlated with instrumental temperature data and indicate that recent warming in the northern tropical Andes is unprecedented over the past two millennia. Furthermore, the magnitude of warming since the Little Ice Age is substantially larger than suggested by high latitude temperature reconstructions. Hydrogen isotope data indicated that colder conditions during the Little Ice Age were accompanied by a decrease in rainfall, likely associated with a southward shift in the position of the ITCZ. Over the past few centuries, warmer temperatures were accompanied by an increase in rainfall and a northward expansion of the tropical rainbelt. Together, these data suggest that the dominant control on the retreat of Andean glaciers has been the unprecedented rate and magnitude of recent warming.

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. Permanent deformation caused by subduction earthquakes in northern Chile

    Science.gov (United States)

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

    2013-06-01

    Earthquakes are accompanied by coseismic and post-seismic rebound: blocks of crust on either side of the fault spring back to their initial, undeformed configuration. This rebound is well documented by space geodetic data, such as the Global Positioning System. Thus, all earthquake-induced deformation of the crust is considered non-permanent and is modelled as an elastic or visco-elastic process. Here, however, we show that earthquakes larger than magnitude 7 in northern Chile caused the crust to deform permanently. We identify millimetre- to metre-scale tension cracks in the crust of the Atacama Desert and use cosmogenic nuclides to date the timing of crack formation. The cracks were formed by between 2,000 and 9,000 individual plate-boundary earthquakes that occurred in the past 0.8-1 million years. We show that up to 10% of the horizontal deformation generated during the earthquakes, recorded by Global Positioning System data and previously assumed to be recoverable, is permanent. Our data set provides a record of permanent strain in the shallow crust of the South American Plate. Although deformation of the deep crust may be predominantly elastic, we conclude that modelling of the earthquake cycle should also include a significant plastic component.

  2. 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.

  3. 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

  4. 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.

  5. Determinación de procesos y áreas de riesgos en los Andes centrales de Chile mediterráneo: Casos de estudio

    Directory of Open Access Journals (Sweden)

    Quintanilla, Víctor

    1994-12-01

    Full Text Available ln the course of the Mountain Hazards Mapping Project in the Central Andes from Chile (Project FONDECYT Nº 482-91 natural hazards were assessed and mapped in the Aconcagua Bassin Test area of the high Andes (2.500 to 4.000 m.. Various geomorphic hazard processes (avalanches, rockfalls, landslide hazards, water activity were mapped on the scale 1:50.000 with a simplified legend. The mountainous area seems to be relatively stable and the rock substratum (mainly granitic is resistant to weathering. The greatest hazards are avalanches and landslides, which have a long recurrence interval and are difficult to predict, although their source areas can be identified.

    [es] Durante la realización del proyecto de Cartografía de Riesgos de Montaña en los Andes Centrales de Chile (Proyecto FONDECYT nº 482- 91 se cartografiaron los riesgos naturales en la cuenca del Aconcagua, altos Andes (2.500 a 4.000 m. Varios riesgos geomorfológicos (avalanchas, caídas de piedras, erosión hídrica fueron cartografiados a escala 1:50.000 con una leyenda simplificada. Las áreas de montaña parecen relativamente estables y el sustrato rocoso (principalmente granítico es resistente a la meteorización.
    Los mayores riesgos son las avalanchas y los deslizamientos, que tienen un largo periodo de recurrencia y son difíciles de predecir, aunque sus áreas fuente pueden ser fácilmente identificadas.
    [fr] Durant la réalisation du projet de cartographie des risques de montagne dans les Andes Centrales du Chili (Projet FONDECYT nº 482-91 on a réalisé des cartographies des risques naturels dans le bassin de Aconcagua, Hautes Andes (2500 à 4000 m. Des risques géomorphologiques variés (avalanches, chutes de pierres, érosion hydrique ont été représentés au 1:50.000ième avec une légende simplifiée. Les zones de montagne paraissent relativement stables et la roche mère (principalement granitique est résistante à la d

  6. The structure of the Chañarcillo Basin: An example of tectonic inversion in the Atacama region, northern Chile

    Science.gov (United States)

    Martínez, F.; Arriagada, C.; Peña, M.; Del Real, I.; Deckart, K.

    2013-03-01

    The Chañarcillo Basin is an Early Cretaceous extensional basin in northern Chile (27-29°S). The folding style of the syn-rift successions along the eastern side of the basin reveals an architecture consisting of a NNE-trending anticline “Tierra Amarilla Anticlinorium”, associated with the inversion of the Elisa de Bordos Fault. A set of balanced cross sections and palinspastic restorations across the basin show that a partially inverted “domino-style” half-graben as the structural framework is most appropriate for reproducing the deformation observed at the surface. This inverted system provides a 9-14 km shortening in the basin. The ages of the synorogenic deposits preserved next to the frontal limb of the “Tierra Amarilla Anticlinorium” suggest that basin inversion occurred close to the “K-T” boundary (“K-T” phase of Andean deformation). We propose that tectonic inversion is the fundamental deformation mechanism, and that it emphasizes the regional importance of inherent Mesozoic extensional systems in the evolution of the northern Chilean Andes.

  7. Reconstruction of Late Cretaceous Magmatic Arcs in the Northern Andes: Single Versus Multiple Arc Systems

    Science.gov (United States)

    Cardona, A.; Jaramillo, J. S.; Leon, S.; Hincapie, S.; Mejia, D.; Patino, A. M.; Vanegas, J.; Zapata, S.; Valencia, V.; Jimenez, G.; Monsalve, G.

    2014-12-01

    Although magmatic rocks are major tracers of the geological evolution of convergent margins, pre-collisional events such as subduction erosion, collisional thrusting or late collisional strike slip segmentation may difficult the recognizing of multiple arc systems and therefore the existence of paleogeographic scenarios with multiple subduction systems. New field, U-Pb geochronology and whole rock geochemistry constraints from the northwestern segment of the Central Cordillera in the states of Antioquia and Caldas (Colombia) are used to understand the nature of the Late Cretaceous arc magmatism and evaluate the existence of single or multiple Pacific and Caribbean arc systems in the growth of the Northwestern Andes. The new results integrated with additional field and published information is used to suggest the existence of at least three different magmatic arcs. (1) An Eastern Continental arc built within a well defined Permian to Triassic continental crust that record a protracted 90-70 Ma magmatic evolution, (2) a 90-80 arc formed within attenuated continental crust and associated oceanic crust, (3) 90-88 Ma arc formed over a Late Cretaceous plateau crust. The eastern arcs were formed as part of double eastern vergent subduction system, where the most outboard arc represent a fringing arc formed over detached fragments of continental crust, whereas the easternmost continental arc growth by the closure an subduction of and older and broad Triassic to Early Jurassic back-arc ocean. Its closure also end up in ophiolite emplacement. The third allochtonous oceanic arc was formed over the Caribbean plateau crust and was accreted to the continental margin in the Late Cretaceous. Ongoing paleomagnetic, deformational, gravimetric and basin analysis will be integrate to test this model and understand the complex Late Cretaceous tectonic evolution of the Northern Andes.

  8. 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...

  9. Calculated WIMP signals at the ANDES laboratory: comparison with northern and southern located dark matter detectors

    CERN Document Server

    Civitarese, O; Mosquera, M E

    2016-01-01

    Weakly Interacting Massive Particles (WIMP) are possible components of the Universe's Dark Matter. The detection of WIMP is signalled by the recoil of the atomic nuclei which form a detector. CoGeNT at the Soudan Underground Laboratory (SUL) and DAMA at the Laboratori Nazionali del Gran Sasso (LNGS) have reported data on annual modulation of signals attributed to WIMP. Both experiments are located in laboratories of the northern hemisphere. Dark matter detectors are planned to operate (or already operate) in laboratories of the southern hemisphere, like SABRE at Stawell Underground Physics Laboratory (SUPL) in Australia, and DM-ICE in the South Pole. In this work we have analysed the dependence of diurnal and annual modulation of signals, pertaining to the detection of WIMP, on the coordinates of the laboratory, for experiments which may be performed in the planned new underground facility ANDES (Agua Negra Deep Experimental Site), to be built in San Juan, Argentina. We made predictions for NaI and Ge-type de...

  10. Detection of recent faulting and evaluation of the vertical offsets from numerical analysis of SAR-ERS-1 images: the example of the Atacama fault zone in northern Chile

    Science.gov (United States)

    Mering, Catherine; Chorowicz, Jean; Vicente, Jean-Claude; Chalah, Cherif; Rafalli, Gaelle

    1995-11-01

    Usually the analysis of high resolution satellite images such as radar SAR ERS-1 images is undertaken by photo-interpretation techniques in order to reveal geological features. The numerical image processing is based on a filtering method designed for a better identification of geological structures on SAR images. The method leads to a mapping of recent faults on which the vertical offset is quantified. As examples, steeply dipping active faults with abrupt scarps are extracted from SAR-ERS1 images of the Central Andes (Atacama Fault zone, Northern Chile). The fault throws are then evaluated with a specific numerical image processing.

  11. 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

  12. 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

  13. Energy from the Andes. The hydropower plant La Confluencia in Chile; Energie aus den Anden. Die Wasserkraftanlage La Confluencia in Chile

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Mathias [Hochschule Regensburg (Germany). Bauingenieurwesen

    2012-11-01

    The author of the contribution under consideration reports on the hydropower plant La Confluencia situated nearly 150 km south of Santiago de Chile (Chile). La Confluencia is a project development of a Norwegian-Australian joint venture of SN Power utilities (Oslo, Norway) and Pacific Hydro (Melbourne, Australia). Constructora Hochtief Tecsa (Santiago, Chile) took over the order to construct the plant completely including planning, construction, equipment and operation. The system concept was developed in collaboration with Poeyry Energy (Zurich, Switzerland). The plant design was devised in cooperation with Intertechne (Curitiba, Brazil), EDIC Ingenieros (Santiago, Chile) and Geocontrol (Madrid, Spain).

  14. 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

  15. 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

    Directory of Open Access Journals (Sweden)

    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

  16. Regional distance shear-coupled PL propagation within the northern Altiplano, central Andes

    Science.gov (United States)

    Swenson, Jennifer L.; Beck, Susan L.; Zandt, George

    1999-12-01

    Properties of the shear-coupled P wavetrain (SPL) from regional earthquakes provide important information about the structure of the crust and upper mantle. We investigate broad-band seismic data from intermediate-depth earthquakes and develop a grid search technique using synthetic seismograms to study the sensitivity of SPL and to model the crustal structure of the northern Altiplano, central Andes. Waveforms from an earthquake that occurred on 1994 December 12 within the Nazca slab beneath the Altiplano display a clear SPL wavetrain at the temporary stations deployed during the BANJO and SEDA experiments. We relocate this event and determine the moment tensor by inverting the complete long-period waveforms. With these source parameters fixed, we perform sensitivity analyses using a reflectivity technique to compute synthetic seismograms at a distance of 313 km (BANJO station 2, SALI). We find that, at this distance, the long-period SPL wavetrain is sensitive to the following model parameters, in order of decreasing sensitivity: crustal VP/VS, mantle VP/VS, average crustal velocity, crustal thickness, focal depth, distance (location), crustal Qα and Qβ, and mantle velocity. We develop a grid search method to investigate the four parameters of the crust/upper mantle model to which the synthetic seismograms are most sensitive at SALI (crustal VP/VS, mantle VP/VS, average crustal velocity, crustal thickness). Trade-offs exist among all four of the model parameters, resulting in a range of acceptable crustal models that provide excellent fits between the data and synthetic seismograms in the passband of 15-100 s at a single station. However, by using data at a range of distances (150-450 km) we find that the model that provides the best overall fit between the data and synthetic seismograms, and thus best approximates the average characteristics of the crust and upper mantle structure of the northern Altiplano, is characterized by an average crustal velocity of 6

  17. 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.

  18. 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

  19. Source apportionment of PM10 and PM2.5 near a large mining zone in Northern Chile

    Science.gov (United States)

    Jorquera, H.

    2008-12-01

    Chile's economic growth is mainly driven by intensive mining activities; currently Chile produces ~ 40% of copper worldwide. Most of those activities are located in northern Chile, in a desert region where strong regional winds contribute with soil erosion as well. The city of Calama (22.4°S, 68.9°W) is about 17 km south of Chuquicamata, one of the largest open pit copper mines in the world, both located on the west edge of the Andes; Calama is at 2,400 m asl and it is 215 km east of the Pacific Ocean. The mining complex releases ~ 21 kton/y of PM10 and ~ 78 kton/y of SO2 from a copper smelter. The levels of ambient PM10 have steadily increased at Calama in the last 5 years, so there is concern about the impacts from copper industry in the city´s inhabitants, most of who work in mining or related economic activities. A campaign was conducted at Calama between October and December 2007, sampling ambient PM10 and PM2.5 at several sites across the city. Filters were analyzed at the Desert Research Institute, Reno, NV for elemental composition by XRF and for elemental and organic carbon using thermal analysis. The application of positive matrix factorization (PMF) model identified four sources contributing to ambient PM2.5: secondary sulfates (49%), traffic emissions (37%), dust street (9%) and copper smelter emissions (5%). In the coarse fraction, four sources were identified: dust street (45%), wind erosion (34%), mineral processing (14%) and copper smelter emissions (7%). No natural background was found for PM2.5. For ambient PM10 the source apportionment obtained is: mining activities (33%), street dust (34%), wind erosion (22%) and traffic emissions (12%). With a current PM10 annual average of 58 μg/m3 and further mining activities projected in the area, there is a big challenge to improve air quality in the populated area close to the mining operations.

  20. 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.

  1. 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

  2. Thickness of the subducting Nazca lithosphere in northern Chile as seen by S receiver functions

    Science.gov (United States)

    Sodoudi, Forough; Asch, Günter; Kind, Rainer; Oncken, Onno; Vilotte, Jean-Pierre; Barrientos, Sergio; Salazar Reinoso, Pablo

    2010-05-01

    Installation of observatories in northern Chile started in 2006 in a close cooperation of the Universidad de Chile (Santiago), the Universidad Catolica del Norte (Antofagasta), the IPGP (Paris), and the GFZ Potsdam. Currently we operate 15 modern seismological stations equipped with STS-2 broadband seismometers. One GEOFON station operated since 2001 completes our dataset in northern Chile. We combined here two methods (P and S receiver function) to have the best vertical as well as horizontal coverage of the area and map the geometry of the subducting Nazca plate. Our high resolution results image the penetration of the Moho of the subducting Nazca plate at depths ranging from 35 km beneath the Coastal Cordillera to an average depth of 80 km beneath the Longitudinal Valley and about 100 km beneath the Precordillera. We found a significant variation in the dip of the subducting Nazca plate obtained from stations located in the northern part (over latitude of 21 deg. South) compared to those located below this latitude. The shape of the Nazca plate shows a shallow dip beneath the southern part and becomes steeper and deeper beneath the northern part of the area, which is coherent with the intermediate seismicity. On the basis of our P and S receiver functions, the lithosphere-asthenosphere boundary of the subducting Nazca plate is at 80 km depth beneath the Coastal Cordillera and dips to a depth of about 120 km beneath the Longitudinal Valley. It becomes 150 km underneath the Precordillera.

  3. Stratigraphic and Petrological Constraints of Cretaceous Subduction Initiation and Arc-Continent Collision in the Northern Andes

    Science.gov (United States)

    Leon, S.; Cardona, A.; Mejia, D.; Parra, M.

    2014-12-01

    Middle to Late-Cretaceous orogenic events in the northern Andes have been commonly reconstructed from the analysis of inland basins or the integration of regional scale thermochronological, geochronological and geochemical datasets from the accreted blocks. In contrast, limited studies have been developed on the stratigraphic and deformational record of magmatic and sedimentary sequences exposed near the suture zones. New field and petrologic data are used to characterize an ophiolite type sequence that outcrops in the western flank from the northwestern segment of the Central Cordillera of Colombia. Stratigraphic analysis indicate the existence of Albian-Aptian deep marine pelitic sequence interbedded with minor chert and thin quartz sandstone beds that apparently change to a volcanic dominate stratigraphy. Deformed ophiolite-like mafic and ultramafic plutonic rocks and isolated pillow lavas are also exposed to the east in fault contact with the pelitic sequence. The pelitic and interlayered volcanic rocks represent the growth of an extensional Early-Cretaceous basin that followed a Late-Jurassic magmatic quiescence in the Northern Andes. The volcano-sedimentary record is probably related to the growth of a fore-arc basin in a new subduction zone that extends until the Late Cretaceous. The deformation and obduction of the ophiolitic association and the fore-arc basin were probably triggered by the Late Cretaceous collision with an allocthonous plateau-arc associated to the migration of the Caribbean plate.

  4. 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.

  5. 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...

  6. 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...

  7. 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 ...

  8. 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

  9. 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.

  10. 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.

  11. 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.

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

    Science.gov (United States)

    Araya, Juan Francisco; Catalán, Ricardo

    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 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. PMID:24715800

  13. 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

  14. Late Oligocene-Early Miocene compressional tectosedimentary episode and associated land-mammal faunas in the Andes of central Chile and adjacent Argentina (32 37°s)

    Science.gov (United States)

    Semper, Thierry; Marshall, Larry G.; Rivano, Sergio; Godoy, Estanislao

    1994-01-01

    A reassessment of the geologic and land-mammal fossil evidence used in attribution of a tectosedimentary episode in the Andes between 32 and 37°S to the Middle Eocene "Incaic tectonic phase" of Peru indicates that the episode occurred during Late Oligocene-Early Miocene times(~ 27-20 Ma). From west to east, three structural domains are recognized for this time span in the study area: a volcanic arc (Chile); a thin-skinned, E-verging fold-thrust belt (Cordillera Principal, Chile-Argentina border strip); and a foreland basin (Argentina). Initiation of thrusting in the Cordillera Principal fold-thrust belt produced the coeval initiation of sedimentation in the foreland basin of adjacent Argentina. This onset of foreland deposition postdates strata bearing a Divisaderan Land Mammal Age fauna (i.e. ~ 35-30 Ma) and is marked at ~ 36°30'S by the base of the "Rodados Lustrosos" conglomerates, which are conformably overlain by sedimentary rocks containing a Deseadan Land Mammal Age fauna (i.e. ~ 29-21 Ma). Geologic relationships between the thick volcanic Abanico (Coya-Machalí) and Farellones formations also demonstrate that this tectosedimentary episode practically ended at ~ 20 Ma at least in the volcanic arc, and was therefore roughly coeval with the major tectonic crisis (~ 27-19 Ma) known in northwestern Andean Bolivia some 1500 km to the north. This strongly suggests that a long, outstanding tectonic upheaval affected at least an extended 12-37°S segment of the Andean margin of South America during Late Oligocene and Early Miocene times.

  15. 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

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. CENOZOIC EXHUMATION OF THE ANTIOQUEÑO PLATEAU, NORTHERN ANDES, COLOMBIA, FROM APATITE LOW-TEMPERATURE THERMOCHRONOLOGY

    Science.gov (United States)

    Restrepo-Moreno, S. A.; Foster, D. A.; O'Sullivan, P. B.; Donelick, R.; Stockli, D. F.

    2009-12-01

    The Antioqueño plateau (AP), in the northernmost Cordillera Central, Colombia, is the most extensive and best preserved relict surface in the Northern Andes. Apatite (U-Th)/He (AHe) and fission track (AFT) results from twenty two samples, collected from paleocrustal depths along two vertical profiles in canyons dissecting the AP, constrain Cenozoic erosional exhumation of this segment of the Andean range. The two profiles exhibit excellent reproducibility of AHe and AFT data. Helium ages increase with elevation from ~22-49 Ma. A marked inflection point in the AHe age-elevation plots at 25 Ma defines the bottom of the post-Oligocene He partial retention zone (PRZ). Virtually invariant ages at ~25 Ma record onset of rapid exhumation in the AP. A more subtle slope change in the PRZ at ~43 Ma is interpreted as a minor exhumation pulse. AFT better defines timing and intensity of Eocene exhumation. AFT ages for both profiles vary from ~30-49 Ma and are consistently older than AHe ages. AFT data display invariant ages (±2σ) between 1500-2400 m elevations while confined track length data exhibit uni-modal distributions with a mean track length of ~14.2 μm. Both facts indicate rapid cooling. This is further supported by virtually concordant AFT and AHe ages for both profiles between 1500 to 2200 m implying that rocks were exhumed from temperatures >120°C to below AHe closure temperature 60°C. Assuming a geothermal gradient of ~25°C/km this corresponds to exhumation rates in the order of 0.5 mm/y, comparable in intensity to the Miocene pulse defined by AHe. Integrated thermal modeling show an episode of rapid cooling at ~43-49 Ma. AFT profiles show an apparent inflection point at ~1400 m, which defines the upper boundary of an apatite partial annealing zone (PAZ) exhumed during the 43-49 Ma cooling event. The position of the PAZ and PRZ relative to the present erosional surface point to average erosion rates of ~0.03 mm/yr, which constitute very low denudation rates

  2. 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.

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

    Science.gov (United States)

    Collado, Gonzalo A

    2015-03-02

    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.

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

    OpenAIRE

    ARRIAGADA, César; Roperch, Pierrick; Mpodozis, Constantino; Fernandez, Rodrigo

    2006-01-01

    International audience; We report paleomagnetic results for 131 sites from the modern forearc of northern Chile (25°S and 28°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° +/- 21.6° counterclockwise to 52.7° +/- 17° clockwise. Jurassic to Early Cretaceous rocks from the Coasta...

  5. 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

  6. 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.

  7. 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...

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Recently active reverse faulting in the Atacama Basin area, northern Chile: Implications for the distribution of convergence across the western South America plate boundary

    Science.gov (United States)

    Shyu, J. H.; Gonzalez, G.; Simons, M.; Aron, F.; Veloso, A.

    2007-12-01

    The western South American margin is one of the most active continental plate boundaries in the world. The ongoing convergence between the Nazca plate, or formerly the Farallon plate, and the South American plate produced the wide deformation belt of the Andes. In order to obtain more information about the active deformations in the central Andean belt to better understand the current distribution of convergence across the orogen, we attempted to map major structures that appear to be active recently by their topographic expressions using SRTM DEM and Landsat satellite images, followed by field observations. Results of our mapping show that there are many reverse faults that may be recently active in the area surrounding the Atacama Basin, in the Preandean Depression in northern Chile. These include a series of active reverse faults and related folds at the southeastern corner of the Atacama Basin, a major fold system that may be produced by an underlying fault just east of the basin, and a series of folds that forms the Cordillera de la Sal in the northern and western part of the basin. At the southeastern corner of the Atacama Basin, several geomorphic features indicate that at least some of the structures there have been active quite recently, including small drainages that cut through the folds and form active alluvial fans. Similar features of active river incision across folds are also present in the northern part of the basin. The fold system east of the basin may be one of the most important structures in the area. Deformed lava flows and deflected drainages indicate that this structure has been active recently, and growth strata near the fold suggest that it has been active for several myr. If so, the structure may be a major reverse fault system that defines the eastern boundary of the Atacama Basin, and may thus be an important onland structure that is responsible for absorbing part of the plate convergence.

  14. 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 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 waters in the Hamburgo Basin may have been recharged during late Pleistocene, when the climate was wetter and a lake filled the intervening Punta Negra Basin, as suggested by recent archaeological

  15. A slow-slipping active fold and thrust system at the SE corner of the Atacama basin, northern Chile

    Science.gov (United States)

    Lin, Y.; Shyu, J. H.; González, G.

    2009-12-01

    The western South American offshore is one of the major active convergent plate boundaries in the world, where the Nazca plate is subducting northeastward beneath the South American plate at a rate of about 84 mm/yr. Despite of this rapid plate convergence, the forearc region of western Andes does not seem to undergo large deformation at present. In order to understand the characteristics and mechanisms of active forearc deformation related to the plate convergence, we investigated tectono-geomorphic features in the area of Tilocalar, near the SE margin of the Atacama Basin in northern Chile, where active structures have been previously identified. To map topographic features produced by active structures, we used a combination of several remote-sensing data sets, including digital elevation models (DEM) made from Shuttle Radar Topographic Mission (SRTM), as well as higher resolution ASTER and QuickBird satellite images. Detailed geomorphic surveys using real time kinematic (RTK) GPS are carried out in the field to obtain high-resolution topographic profiles across these features. We also performed 40Ar/39Ar dating of deformed volcanic rocks in order to determine the long-term slip rates of the active structures. The hyper-aridity of the Atacama Basin results in extremely low erosion and sedimentation rates in the area. As a result, the present relief of land surface is mostly produced by neotectonic activity, and can be used as deformation marker. In the Tilocalar area, several N-S trending ridges are present. These ridges, generally several tens of meters high, are likely formed by asymmetric anticlines or monoclines with steep forelimbs facing east, and these folds are likely fault-propagation folds produced by underlying thrust faults. We suggest that these faults merge at depth to become a major active thrust system. From 40Ar/39Ar plateau ages, we found that the surface ignimbrites mostly deposited in latest Pliocene (2.3~4.3 Ma). If the structures have been

  16. 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.

  17. 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.

  18. 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.

  19. 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...

  20. 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.

  1. Triassic rift-related sedimentary basins in northern Chile (24° 29°S)

    Science.gov (United States)

    Suarez, M.; Bell, C. M.

    1992-10-01

    Triassic rocks in northern Chile (latitude 24°-29°S) include marine and continental rift-related sedimentary deposits, associated with basaltic, andesitic, and silicic volcanic rocks. Five main successions include the deposits of two marine basins (Profeta and San Félix) separated by three continental basins (Cifuncho, La Ternera, and La Coipa). The marine strata include turbidites and debris flow deposits interpreted as coarse-grained fan-delta sediments. The continental sediments include lacustrine fan delta, open lake, braided river, alluvial fan, and sabkha deposits. The widespread fan-delta systems (both marine and lacustrine), together with abrupt lateral and vertical facies discontinuities and large-scale depositional cycles, are indicative of rift-controlled sedimentation. The associated magmatic activity indicates that this rifting was the product of subduction-related extension or strike-slip movement on the active plate margin. Triassic rifting was followed in Late Triassic to Early Jurassic times by widespread thermotectonic subsidence.

  2. Mid-Holocene Climate and Culture Change in the Atacama Desert, Northern Chile

    Science.gov (United States)

    Grosjean, Martin; Núñez, Lautaro; Cartajena, Isabel; Messerli, Bruno

    1997-09-01

    Twenty archaeological campsites intercalated between more than 30 debris flows caused by heavy rainfall events between 6200 and 3100 14C yr B.P. have recently been discovered at Quebrada Puripica in the Atacama Desert of northern Chile. This record provides detailed information about extreme, short-lived climatic events during the hyperarid mid-Holocene period. For the first time, we found evidence of continuous human occupation in this area, filling the regional hiatus in the Atacama basin ("Silencio Arqueologico") between 8000 and 4800 14C yr B.P. The transformation of Early Archaic hunters into the complex Late Archaic cultural tradition was an adaptive process. During this time, the site was a local ecological refuge with abundant resources in a generally hostile environment.

  3. The Late Paleozoic evolution of the Gondwanaland continental margin in northern Chile

    Science.gov (United States)

    Bell, C. M.

    Tectonic activity on the Gondwanaland continental margin in northern Chile and northwestern Argentina has been continuous from the early Paleozoic to the present. Paleozoic accretion resulted from the buildup of accretionary and magmatic arc complexes, and possibly from the addition of exotic terranes. Paleozoic strata between 25°S and 29°S in northern Chile comprise two north-south elongated strips separated by a 100-km-wide graben infilled with younger rocks. The western strip consists of deep-sea turbidites and basic lavas of the Devonian or Early Carboniferous Las Tórtolas Formation. Subduction of these rocks during Carboniferous times produced the Chañaral mélange in the area south of 26°30'S. The mélange probably resulted from intrastratal movements of partly consolidated strata within an accretionary wedge. Further tectonic deformation of both the turbidites and the mélange was produced by northeast directed subduction. The subduction complex is bounded to the east by the Atacama strike-slip fault system. To the east of the graben are relatively undeformed Early Carboniferous lacustrine sedimentary rocks of the Chinches Formation. These were deposited in a deep, elongated basin, possibly of pull-apart type resulting from strike-slip movement parallel to the coastline. Late Carboniferous to Early Permian magmatic activity superimposed on both these sedimentary successions suggests seaward migration of the subduction zone. The development of the Mesozoic and Cenozoic Andean complex, which overlies the Paleozoic rocks with a marked unconformity, was not accompanied by the accretion of a further subduction complex.

  4. Drinking water arsenic in northern Chile: high cancer risks 40 years after exposure cessation

    Science.gov (United States)

    Steinmaus, Craig M.; Ferreccio, Catterina; Romo, Johanna Acevedo; Yuan, Yan; Cortes, Sandra; Marshall, Guillermo; Moore, Lee E.; Balmes, John R.; Liaw, Jane; Golden, Todd; Smith, Allan H.

    2013-01-01

    Background Millions of people worldwide are exposed to arsenic-contaminated water. In the largest city in northern Chile (Antofagasta) >250,000 people were exposed to high arsenic drinking water concentrations from 1958 until 1970 when a water treatment plant was installed. Because of its unique geology, limited water sources, and good historical records, lifetime exposure and long-term latency patterns can be assessed in this area with better accuracy than in other arsenic-exposed areas worldwide. Methods We performed a population-based case-control study in northern Chile from October 2007 to December 2010 involving 232 lung and 306 bladder cancer cases and 640 age- and gender-matched controls, with detailed information on past exposure and potential confounders, including smoking and occupation. Results Bladder cancer odds ratios for quartiles of average arsenic concentrations in water before 1971 (335 µg/L) were 1.00, 1.36 (95% confidence interval, 0.78 to 2.37), 3.87 (2.25 to 6.64), and 6.50 (3.69 to 11.43), respectively. Corresponding lung cancer odds ratios were 1.00, 1.27 (0.81 to 1.98), 2.00 (1.24 to 3.24), and 4.32 (2.60 to 7.17). Bladder and lung cancer odds ratios in those highly exposed in Antofagasta during 1958–70 but not thereafter were 6.88 (3.84 to 12.32) and 4.35 (2.57 to 7.36), respectively. Conclusions The lung and bladder cancer risks that we found up to 40 years after high exposures have ended are very high. Impact Our findings suggest that prevention, treatment, and other mortality reduction efforts in arsenic-exposed countries will be needed for decades after exposure cessation. PMID:23355602

  5. 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.

  6. 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

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

    OpenAIRE

    ARRIAGADA, César; Cobbold, Peter,; Roperch, Pierrick

    2006-01-01

    19 p.; International audience; 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, t...

  8. Constraining age and rate of deformation in the northern Bolivian Andes from cross sections, cooling ages, and thermokinematic modeling

    Science.gov (United States)

    McQuarrie, N.; Ehlers, T. A.; Rak, A. J.

    2015-12-01

    A critical component in assessing the viability of proposed plate tectonic or geodynamic processes in regions of convergence is the expected or predicted age and rate of deformation in the overriding plate. Commonly, age of deformation is inferred through geochronology of foreland basin and wedge-top sedimentary rocks and bedrock thermochronometer cooling signals. In Bolivia the original pulse of deformation of the fold-thrust belt is argue to be as young as 38-25 Ma based on the age of synorogenic strata or as old as 65-45 Ma due to proposed foreland basin rocks deposited in the Bolivian Altiplano. The large discrepancies in proposed age, rate and magnitude of deformation through the Bolivian Andes limit our ability to relate age and rate of shortening to internal geodynamic or external plate tectonic processes. We evaluate permissible ranges in age of initiation and rate of deformation through a forward kinematic model of the northern Bolivian fold-thrust belt. Each step of deformation accounts for isostatic loading from thrust faults and subsequent erosional of structural highs. The kinematic model predicts an evolution of flexural basins into which synorogenic sediments are deposited allowing us to fully integrate age of exhumation and deposition to age and magnitude of deformation. By assigning an age to each deformation step, we create a range of velocity vectors that are input into the thermokinematic model Pecube, which predicts thermochronometer cooling histories based on kinematics, topography, thermal parameters and shortening rates. We match the pattern of predicted ages with the across strike pattern of measured zircon fission track, apatite fission track and apatite (U-Th)/ He cooling ages. The sensitivity of modeled thermochronologic data to the age at which deformation initiates indicate that northern Bolivian EC started deforming at 50 Ma and may have begun as early as 55 Ma. The acceptable velocity envelope for the modeled section permits either a

  9. [Diversity and dynamics of a high sub-Andean forest from Northern Andes, Colombia].

    Science.gov (United States)

    Restrepo, Jesús Oswaldo Velásquez; Maniguaje, Nancy Lorena; Duque, Alvaro Javier

    2012-06-01

    The sub-Andean forests are characterized by a high biodiversity, but little is known about their natural dynamics. In order to generate new information, this study assessed two permanent plots of one hectare each, in the Northern Andean area of the Western Cordillera, Colombia. Methodology included the evaluation of diversity patterns, above ground biomass (AGB) dynamics, and mortality and recruitment rates. Besides, we used the Fisher's Alpha index to calculate species diversity. Forest dynamics and AGB were evaluated in both plots by means of three censuses carried out within a nine years period. In total, we found 1 664 individuals with diameter at breast height (DBH)> or =10cm belonging to 222 species, 113 genera and 60 families. Mean species richness was of 156 species/ha and a mean Fisher's Alpha index of 56.2/ha. The mortality rate was 0.88% and recruitment was 1.16%, which did not allow to lay any external effect of global warming or climate change on individual forest dynamics. However, the mean AGB was 243.44+/-9.82t/ha, with an annual average increase of 2.9t/ha, a higher value than the one reported in other studies of high sub-Andean forests, which suggests that equilibrium in terms of the AGB have not yet been reached. Besides, according to field observations, a recovery process, from a disturbance that occurred in the past, might be on his way.

  10. 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

  11. A Late-Glacial/Holocene Pollen Record from the Eastern Andes of Northern Peru

    Science.gov (United States)

    Hansen, Barbara C. S.; Rodbell, Donald T.

    1995-09-01

    A pollen and sediment record of a core 4.2-m-long from Laguna Baja (7°42' S, 77°32' W, 3575 m) in the Cordillera Oriental of northern Peru suggests several episodes of major vegetational and climatic change over the past 13,000 yr. The oldest pollen assemblage consists of a mixture of paramo elements (tropical alpine vegetation), including high percentages of Poaceae (40%) that decline upward, moist montane forest (Compositae and Polylepis), and wet montane forest (e.g., Hedyosmum and Podocarpaceae). Organic carbon content range from 60%), with high percentages of Jamesonia, a fern characteristic of paramo and decreasing values of Plantago tubulosa and the wet montane forest elements Hedyosmum and Podocarpaceae. Charcoal percentages are at a maximum during this period, magnetic susceptibility and sand percentages are high, and percentages of organic matter are low. Several explanations for these changes are possible, including a reduction in temperature and moisture, more frequent periods of aridity with increased fires, or natural succession. The Holocene record begins with pronounced increases in organic carbon and pollen of wet montane forest, primarily Hedyosmum , Podacarpaceae, and Urticales. High values of Podocarpaceae pollen (>35%) and a decline in charcoal suggest temperature and moisture levels above modern-day values. Wet montane forest pollen remain high and charcoal values are low from about 10,000 to 6000 yr B.P., suggesting that warm and moist conditions prevailed for about 4000 yr. Subsequently Podocarpaceae and Urticales decline, and for a brief time Alnus is prominent in the pollen record. Following the Alnus maximum at about 5000 yr B.P., Poaceae, Ambrosia and Chenopodiaceae/Amaranthaceae become frequent. Increased paramo and disturbance indicator pollen suggest increased anthropogenic activities in this region from the middle Holocene to the present.

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

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    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.

  13. 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...

  14. 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...

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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

  20. Eruptive history of Chimborazo volcano (Ecuador): A large, ice-capped and hazardous compound volcano in the Northern Andes

    Science.gov (United States)

    Samaniego, Pablo; Barba, Diego; Robin, Claude; Fornari, Michel; Bernard, Benjamin

    2012-04-01

    New fieldwork, radiometric and whole-rock chemical data permit the reconstruction of the main eruptive stages of the Chimborazo compound volcano, the highest summit of the Northern Andes. Chimborazo is composed of three successive edifices. The Basal Edifice (CH-I) was active from ~ 120 to 60 ka and resulted in a large, mostly effusive edifice which was built up during two stages of cone-building, terminating with the formation of a dome complex. This edifice was affected by a huge sector collapse around 65-60 ka which produced a major debris avalanche that spread out into the Riobamba basin, covering about 280 km2 with an average thickness of 40 m and a total volume of ~ 10-12 km3. After the emplacement of the Riobamba debris avalanche, eruptive activity resumed at the eastern outlet of the avalanche scar and was responsible for the construction of a less voluminous, Intermediary Edifice (CH-II), whose current remnants are the Politécnica and Martínez peaks. This edifice developed from 60 to 35 ka. Lastly, eruptive activity shifted to the west, leading to the construction of the morphologically well-preserved Young Cone (CH-III) which currently forms the highest summit (Whymper). The average eruptive rate of Chimborazo volcano is 0.5-0.7 km3/ka. However, looking at the three successive edifices individually, we estimate that there has been a progressive decrease in magma output rate from the Basal Edifice (0.7-1.0 km3/ka), through the Intermediary Edifice (0.4-0.7 km3/ka) to the Young Cone (~ 0.1 km3/ka). However, during the main cone-building stages, the peak eruption rates are markedly higher, indicating significant variations in the magma output rate during the lifespan of this arc volcano. During the Holocene, the Chimborazo eruptive activity consisted of small-volume explosive events that occurred at quite regular intervals, between about 8000 and 1000 yr ago. Since the last eruption occurred between the early part of the 5th century and the end of the 7th

  1. 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 (S3), followed by a final phase of fluid mixing and boiling (S4). The evolution of hydrothermal alteration at Tolhuaca has produced a mineralogical, hydrological and structural vertical segmentation of the system through the development of a low-permeability, low-cohesion clay-rich cap at shallow depth. The quantitative chemical analyses of fluid inclusions and borehole fluids reveal a significant change in chemical conditions during the evolution of Tolhuaca. Whereas borehole (present-day) fluids are rich in Au, B and As, but Cu-poor (B/Na ~ 100.5, As/Na ~ 10- 1.1, Cu/Na ~ 10- 4.2), the paleofluids trapped in fluid inclusions are Cu-rich but poor in B and As (B/Na ~ 10- 1, As/Na ~ 10- 2.5, Cu/Na ~ 10- 2.5 in average). We interpret the fluctuations in fluid chemistry at Tolhuaca as the result of transient supply of metal-rich, magmatically derived fluids where As, Au and Cu are geochemically decoupled. Since these fluctuating physical and chemical conditions at the reservoir produced a mineralogical vertical segmentation of the system that affects the mechanical and hydrological properties of host rock, we explored the effect of the development of a low-cohesion low-permeability clay cap on the conditions

  2. 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

  3. Advances in ammonite biostratigraphy of the marine Atacama basin (Lower Cretaceous), northern Chile, and its relationship with the Neuquén basin, Argentina

    Science.gov (United States)

    Mourgues, Francisco Amaro

    2004-09-01

    Preliminary results about the Lower Cretaceous ammonite biostratigraphy of northern Chile reveal eight fossiliferous levels: Lower-Upper Valanginian neocomitid and olcostephanid faunas in the Punta del Cobre and Abundancia Formations and Upper Hauterivian-Barremian crioceratid in the Nantoco, Totoralillo, and Pabellón Formations. The faunal affinities with the Neuquén are strong during the Valanginian and Hauterivian. In contrast, during the Barremian and Aptian, the ammonites show affinities with Austral, California, and Tethys basinal faunas. The Lower Valanginian-lower Upper Aptian series in northern Chile comprises two sedimentary cycles separated by a regressive pulse of Upper Hauterivian-Lower Barremian age. This pulse may be equivalent to the regression that ended the Early Cretaceous marine cycle in central Chile and central west Argentina, where the second marine sedimentary cycle observed in northern Chile is not represented.

  4. Triassic alluvial braidplain and braided river deposits of the La Ternera Formation, Atacama region, northern Chile

    Science.gov (United States)

    Bell, C. M.; Suárez, M.

    1995-01-01

    The La Ternera Formation is a thick (>2,100 m) succession of terrigenous clastic sediments, with andesitic and basaltic intercalations, exposed in the Quebrada de Paipote area of the Atacama Region, northern Chile. The strata were deposited in an active rift basin during Late Triassic to (?) Early Jurassic times. The lower 1,000 m of the studied elastic succession comprises pebbly granule paraconglomerates, unconformably overlying Upper Paleozoic sedimentary successions, volcanics, and granitoids. These sediments were derived from the east and are interpreted as braid-plain deposits. The upper 800 m of the succession comprises interbedded orthoconglomerates, sandstones and mudstones. Abundant plant fossils include trees in growth position and carbonaceous horizons. Small scale depositional cycles were the product of migrating braided-river channel systems. Larger scale successions resulted from tectonic uplift. The sediments of the La Ternera Formation were derived predominantly from a tectonically uplifted area of Upper Paleozoic acidic volcanic and plutonic rocks (Pantanoso Formation, Choiyoi Group). Active uplift on the eastern margin of the sedimentary basin probably occurred along north-south trending faults. Continued subsidence of the basin resulted in a Sinemurian to Bajocian marine transgression. Occurrences of Triassic andesitic and basaltic volcanic rocks both to the west and the east of the La Ternera formation suggest deposition in an intea-volcanic graben or half-graben.

  5. Tectonic rotations and internal structure of Eocene plutons in Chuquicamata, northern Chile

    Science.gov (United States)

    Somoza, R.; Tomlinson, A. J.; Zaffarana, C. B.; Singer, S. E.; Puigdomenech Negre, C. G.; Raposo, M. I. B.; Dilles, J. H.

    2015-07-01

    A paleomagnetic and AMS study on Eocene plutonic complexes in the Calama area, northern Chile, reveals high-temperature, high-coercivity magnetizations of dominantly thermoremanent origin and magnetic fabrics controlled by magnetite. The paleomagnetic results indicate that ~ 43 Ma plutons underwent clockwise tectonic rotation, whereas adjacent ~ 39 Ma plutons did not undergo discernible rotation. This points to a middle Eocene age for the younger tectonic rotations associated with the Central Andean Rotation Pattern in the Chuquicamata-Calama area. The petrofabric in these rocks formed under conditions ranging from purely magmatic (i.e. before full crystallization) to low-temperature solid-state deformation. AMS and paleomagnetism suggest that the plutonic bodies were formed by progressive amalgamation of subvertical magma sheets spanning multiple magnetic polarity chrons. The parallelism between magmatic and tectonic foliations suggests that regional tectonic stress controlled ascent, emplacement and rock deformation during cooling. In this context, we suggest that magma ascent and emplacement in the upper crust likely exploited Mesozoic structures which were locally reactivated in the Eocene.

  6. Fish larvae retention linked to abrupt bathymetry at Mejillones Bay (northern Chile during coastal upwelling events

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    Pablo M Rojas

    2014-11-01

    Full Text Available The influence of oceanic circulation and bathymetry on the fish larvae retention inside Mejillones Bay, northern Chile, was examined. Fish larvae were collected during two coastal upwelling events in November 1999 and January 2000. An elevated fish larvae accumulation was found near an oceanic front and a zone of low-speed currents. Three groups of fish larvae were identified: the coastal species (Engraulis ringens and Sardinops sagax, associated with high chlorophyll-a levels; larvae from the families Phosichthyidae (Vinciguerria lucetia and Myctophidae (Diogenichthys laternatus and Triphoturus oculeus, associated with the thermocline (12°C, and finally, larvae of the families Myctophidae (Diogenichthys atlanticus and Bathylagidae (Bathylagus nigrigenys, associated with high values of temperature and salinity. The presence of a seamount and submarine canyon inside Mejillones Bay appears to play an important role in the circulation during seasonal upwelling events. We propose a conceptual model of circulation and particles retention into Mejillones Bay. The assumption is that during strong upwelling conditions the flows that move along the canyon emerge in the centre of Mejillones Bay, producing a fish larvae retention zone. Understanding the biophysical interactions responsible to trap and/or concentrate particles is essential to protect these fragile upwelling ecosystems.

  7. 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

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

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    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.

  9. Provenance through the limit: integrated provenance from the Devonian sedimentary and basement rocks from the northern segment of the Eastern Cordillera of the Colombian Andes

    Science.gov (United States)

    Cardona, Agustin; Valencia, Victor; Lotero, Andrea; Villafañez, Yohana; Augustsson, Carita; Bayona, German; Ibañez, Mauricio

    2013-04-01

    The provenance record of sedimentary rocks is sometimes the only available archive of the geological evolution in continuously active continental margins where continuous exhumation, erosion and along strike fragmentation of continental margins destroy geological evidences. New integrated provenance constraints from segmented exposures of Devonian rocks of the northern segment of the Eastern Cordillera of Colombia are used to reconstruct overimposed Paleozoic, Mesozoic and Cenozoic paleogeographic scenarios of the northern Andes. Sandstones from deltaic to platform environments are characterized by very high quartz contents, stable to ultrastable heavy minerals and mostly angular fragments. U-Pb detrital zircon geochronology reveals prominent Silurian to Ordovician and Mesoproterozoic (Grenvillian) age populations with minor Devonian zircons. Tourmaline geochemistry and detrital quarz characterization suggest prominent low grade metamorphic sources. These provenance fingerprints can be related to the erosion of the older metasedimentary basement exposed in the same region and record the transition from a terrane collisional event to the formation of a new subduction zone before the final Late Paleozoic events that end in the agglutination of Pangea. The U-Pb detrital record of the Devonian and basement rocks of the Eastern Cordillera are also comparable with Early to Middle Paleozic Paleozoic rocks form the Northern segment of the eastern Peruvian Andes re-inforcing the view of along strike terrane thousand of kilometer transport along the Mesozoic proto-Andean margin. Petrographic and heavy mineral petrofacies and stratigraphic correlation between Devonian localities are also used as piercing points to document Cenozoic ten of kilometers strike slip displacements along the northern termination of the Eastern Cordillera.

  10. 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...

  11. Arsenic methylation and lung and bladder cancer in a case-control study in northern Chile

    Energy Technology Data Exchange (ETDEWEB)

    Melak, Dawit [Global Health Sciences, University of California, San Francisco, San Francisco, CA (United States); Ferreccio, Catterina [Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago (Chile); Kalman, David [School of Public Health and Community Medicine, University of Washington, Seattle, WA (United States); Parra, Roxana [Hospital Regional de Antofagasta, Antofagasta (Chile); Acevedo, Johanna; Pérez, Liliana; Cortés, Sandra [Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago (Chile); Smith, Allan H.; Yuan, Yan; Liaw, Jane [Arsenic Health Effects Research Group, School of Public Health, University of California, Berkeley, Berkeley, CA (United States); Steinmaus, Craig, E-mail: craigs@berkeley.edu [Arsenic Health Effects Research Group, School of Public Health, University of California, Berkeley, Berkeley, CA (United States); Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, Oakland, CA (United States)

    2014-01-15

    In humans, ingested inorganic arsenic is metabolized to monomethylarsenic (MMA) then to dimethylarsenic (DMA), although this process is not complete in most people. The trivalent form of MMA is highly toxic in vitro and previous studies have identified associations between the proportion of urinary arsenic as MMA (%MMA) and several arsenic-related diseases. To date, however, relatively little is known about its role in lung cancer, the most common cause of arsenic-related death, or about its impacts on people drinking water with lower arsenic concentrations (e.g., < 200 μg/L). In this study, urinary arsenic metabolites were measured in 94 lung and 117 bladder cancer cases and 347 population-based controls from areas in northern Chile with a wide range of drinking water arsenic concentrations. Lung cancer odds ratios adjusted for age, sex, and smoking by increasing tertiles of %MMA were 1.00, 1.91 (95% confidence interval (CI), 0.99–3.67), and 3.26 (1.76–6.04) (p-trend < 0.001). Corresponding odds ratios for bladder cancer were 1.00, 1.81 (1.06–3.11), and 2.02 (1.15–3.54) (p-trend < 0.001). In analyses confined to subjects only with arsenic water concentrations < 200 μg/L (median = 60 μg/L), lung and bladder cancer odds ratios for subjects in the upper tertile of %MMA compared to subjects in the lower two tertiles were 2.48 (1.08–5.68) and 2.37 (1.01–5.57), respectively. Overall, these findings provide evidence that inter-individual differences in arsenic metabolism may be an important risk factor for arsenic-related lung cancer, and may play a role in cancer risks among people exposed to relatively low arsenic water concentrations. - Highlights: • Urine arsenic metabolites were measured in cancer cases and controls from Chile. • Higher urine %MMA values were associated with increased lung and bladder cancer. • %MMA-cancer associations were seen at drinking water arsenic levels < 200 μg/L.

  12. 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

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

    Directory of Open Access Journals (Sweden)

    Fabian J Tapia

    Full Text Available 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

  14. The Geographic Distribution of a Tropical Montane Bird Is Limited by a Tree: Acorn Woodpeckers (Melanerpes formicivorus and Colombian Oaks (Quercus humboldtii in the Northern Andes.

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    Benjamin G Freeman

    Full Text Available Species distributions are limited by a complex array of abiotic and biotic factors. In general, abiotic (climatic factors are thought to explain species' broad geographic distributions, while biotic factors regulate species' abundance patterns at local scales. We used species distribution models to test the hypothesis that a biotic interaction with a tree, the Colombian oak (Quercus humboldtii, limits the broad-scale distribution of the Acorn Woodpecker (Melanerpes formicivorus in the Northern Andes of South America. North American populations of Acorn Woodpeckers consume acorns from Quercus oaks and are limited by the presence of Quercus oaks. However, Acorn Woodpeckers in the Northern Andes seldom consume Colombian oak acorns (though may regularly drink sap from oak trees and have been observed at sites without Colombian oaks, the sole species of Quercus found in South America. We found that climate-only models overpredicted Acorn Woodpecker distribution, suggesting that suitable abiotic conditions (e.g. in northern Ecuador exist beyond the woodpecker's southern range margin. In contrast, models that incorporate Colombian oak presence outperformed climate-only models and more accurately predicted the location of the Acorn Woodpecker's southern range margin in southern Colombia. These findings support the hypothesis that a biotic interaction with Colombian oaks sets Acorn Woodpecker's broad-scale geographic limit in South America, probably because Acorn Woodpeckers rely on Colombian oaks as a food resource (possibly for the oak's sap rather than for acorns. Although empirical examples of particular plants limiting tropical birds' distributions are scarce, we predict that similar biotic interactions may play an important role in structuring the geographic distributions of many species of tropical montane birds with specialized foraging behavior.

  15. 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.

  16. 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

  17. High-resolution image of the geometry and thickness of the subducting Nazca lithosphere beneath northern Chile

    Science.gov (United States)

    Sodoudi, F.; Yuan, X.; Asch, G.; Kind, R.

    2011-04-01

    Results obtained from S and P receiver functions produced a clear image of the top and bottom of the subducting Nazca lithosphere beneath northern Chile. Using data from the teleseismic events recorded at 15 permanent Integrated Plate Boundary Observatory Chile (IPOC) stations, we obtained new constraints on the geometry and thickness of the descending Nazca lithosphere. We observed the subducted crust of the Nazca plate at depths ranging from 50 km beneath the Coastal Cordillera down to 110 km beneath the Western Cordillera. We found significant along-strike variations in the geometry of the Nazca plate beneath northern Chile. On closer inspection, it appears that the oceanic Nazca plate is divided into two distinct segments as it descends beneath the continental South American plate. The transition from the relatively steeper (˜23°) and deeper slab to the north of 21°S to the flatter southern segment (˜19°) is shown reasonably clearly by our data. This feature could well be associated with variations in the curvature of the plate margin and the geometry of the Chile trench, which is mainly curved to the north of 21°S. We have also mapped the continental Moho of the South American plate at depths ranging between 60 and 70 km to the east of the Longitudinal Valley. Beneath the Coastal Cordillera, this boundary becomes invisible, probably due to the serpentinization of the forearc mantle wedge that reduces the velocity in the uppermost mantle. The base of the subducted Nazca plate was clearly identified as a sharp boundary in the results obtained from the P and S receiver functions. The thickness of the subducted oceanic Nazca plate, which has an age of ˜50 My, is estimated to be ˜50 km. Although this thickness is consistent with that predicted by thermal gradients, the explanation of the sharpness of the lithosphere-asthenosphere boundary may require another mechanism such as hydration or melting.

  18. Microbial eukaryote diversity in the marine oxygen minimum zone off northern Chile

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    D. Joshua eParris

    2014-10-01

    Full Text Available Molecular surveys are revealing diverse eukaryotic assemblages in oxygen-limited ocean waters. These communities may play pivotal ecological roles through autotrophy, feeding, and a wide range of symbiotic associations with prokaryotes. We used 18S rRNA gene sequencing to provide the first snapshot of pelagic microeukaryotic community structure in two cellular size fractions (0.2-1.6 µm, >1.6 µm from seven depths through the anoxic oxygen minimum zone (OMZ off northern Chile. Sequencing of >154,000 amplicons revealed contrasting patterns of phylogenetic diversity across size fractions and depths. Protist and total eukaryote diversity in the >1.6 µm fraction peaked at the chlorophyll maximum in the upper photic zone before declining by ~50% in the OMZ. In contrast, diversity in the 0.2-1.6 µm fraction, though also elevated in the upper photic zone, increased four-fold from the lower oxycline to a maximum at the anoxic OMZ core. Dinoflagellates of the Dinophyceae and endosymbiotic Syndiniales clades dominated the protist assemblage at all depths (~40-70% of sequences. Other protist groups varied with depth, with the anoxic zone community of the larger size fraction enriched in euglenozoan flagellates and acantharean radiolarians (up to 18% and 40% of all sequences, respectively. The OMZ 0.2-1.6 µm fraction was dominated (11-99% by Syndiniales, which exhibited depth-specific variation in composition and total richness despite uniform oxygen conditions. Metazoan sequences, though confined primarily to the 1.6 µm fraction above the OMZ, were also detected within the anoxic zone where groups such as copepods increased in abundance relative to the oxycline and upper OMZ. These data, compared to those from other low-oxygen sites, reveals variation in OMZ microeukaryote composition, helping to identify clades with potential adaptations to oxygen-depletion.

  19. 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).

  20. 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.

  1. 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.

  2. High resolution image of the Lithosphere-Asthenosphere Boundary of the subducting Nazca plate beneath northern Chile

    Science.gov (United States)

    Sodoudi, F.; Yuan, X.; Asch, G.; Kind, R.

    2010-12-01

    Results obtained from S and P receiver functions produced a clear image of the top and bottom of the subducting Nazca lithosphere beneath northern Chile. Using data from the teleseismic events recorded at 15 permanent IPOC (Integrated Plate boundary Observatory Chile) stations, we were able to obtain new constraints on the shape and thickness of the descending Nazca lithosphere. We observed the subducted crust of the Nazca plate at depths ranging from 40 km beneath the Coastal Cordillera down to 110 km beneath the Western Cordillera. We found significant along-strike variations in the geometry of the Nazca plate beneath northern Chile. On closer inspection, it appears that the oceanic Nazca plate is divided into two distinct segments as it descends beneath the continental South American plate. The transition from the relatively steeper and deeper slab to the north of 21° S to the flatter southern segment is shown reasonably clearly by our data. This feature could well be associated with variations in the curvature of the plate margin and the geometry of the Chile trench, which is mainly curved to the north of 21° S. We have also mapped the continental Moho of the South American plate at depths ranging between 60-70 km to the east of the Longitudinal Valley. Beneath the Coastal Cordillera, this boundary becomes invisible, probably due to the serpentinization of the forearc mantle wedge. The Lithosphere-Astheonsphere Boundary (LAB) of the subducted Nazca plate was clearly identified as a sharp boundary in the results obtained from the P and S receiver functions. The LAB lies at a depth of 80 km beneath the coastal area and dips from a depth of 100 km beneath the Coastal Cordillera to about 150 km underneath the Western Cordillera. High frequency PRF data enabled us to make confident estimates of the top and bottom of the Nazca lithosphere, which results in a lithospheric thickness of 57-60 km. In relation to the age of the Nazca plate, which is assumed to be ~ 50

  3. ASTER Andes

    Science.gov (United States)

    2000-01-01

    In this image of the Andes along the Chile-Bolivia border, the visible and infrared data have been computer enhanced to exaggerate the color differences of the different materials. The scene is dominated by the Pampa Luxsar lava complex, occupying the upper right two-thirds of the scene. Lava flows are distributed around remnants of large dissected cones, the largest of which is Cerro Luxsar. On the middle left edge of the image are the Olca and Parumastrato volcanoes, which appear in blue due to a lack of vegetation (colored red in this composite). This image covers an area 60 kilometers (37 miles) wide and 60 kilometers (37 miles) long in three bands of the reflected visible and infrared wavelength region. It was acquired on April 7, 2000.The image is located at 21 degrees south latitude, 68.3 degrees west longitude. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high-resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping and monitoring dynamic conditions and temporal change. Examples of applications include monitoring glacial advances and retreats

  4. Comparison of co-seismic and post-seismic slip of large earthquakes in southern Peru and northern Chile

    Science.gov (United States)

    Pritchard, M. E.; Ji, C.; Simons, M.; Klotz, J.

    2003-12-01

    We use InSAR, GPS, and seismic data to constrain the location of co-seismic and post-seismic slip on the subduction interface in southern Peru and northern Chile. We focus on the July 30, 1995, {M}w~8.1 and the January 30, 1998, {M}w~7.1 northern Chile earthquakes as well as the November 12, 1996, {M}w~7.7 and June 23, 2001, {M}w~8.4 southern Peru earthquakes. For all four earthquakes, we invert body-wave seismic waveforms and geodetic data (InSAR for all earthquakes and GPS where available) both jointly and separately for co-seismic slip. In northern Chile, we constrain the temporal and spatial evolution of post-seismic after-slip using about 30 interferograms spanning 1995-2000 and GPS data from the German SAGA array (spanning 1995-1997, including vertical displacements). In southern Peru, we use InSAR data, and GPS data from the Arequipa station to constrain post-seismic after-slip. Comparison of these events provides insight into the rupture process of large subduction zone earthquakes and the mechanisms of post-seismic after-slip. The plate tectonic setting for all the earthquakes is similar (convergence rate, plate age, etc.), but the amount of post-seismic after-slip is different. There is significant slip after the 2001 earthquake (equivalent to approximately 20% of the co-seismic moment), but compared to other recent subduction zone earthquakes, there is little slip following the other three events. The different amounts of post-seismic slip are not obviously related to differences in the dynamic ruptures of each event, but might be related to along-strike variations in material properties (like sediment thickness).

  5. 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.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.

  6. 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...

  7. 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

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  10. An entomological and seroepidemiological study of the vectorial-transmission risk of Chagas disease in the coast of northern Chile.

    Science.gov (United States)

    González, C R; Reyes, C; Canals, A; Parra, A; Muñoz, X; Rodríguez, K

    2015-12-01

    Four species of triatomines are known from Chile: Triatoma infestans Klug, Mepraia spinolai Porter, M. gajardoi Frías, Henry & González, and M. parapatrica Frías (Hemiptera: Reduviidae), the last three are endemic. The geographical distribution of M. gajardoi includes the coastal areas in the north of Chile between 18° and 21°S, an area with both a resident workforce and summer-season visitors. A study was developed to assess the risk of vectorial transmission of Chagas disease by M. gajardoi in hut settlements on the coast of the Tarapacá Region, in particular in Caleta San Marcos and Caleta Río Seco. The study comprised fingerstick sampling of 95 persons, venous samples from 29 domestic dogs and capture of 52 triatomines, from both fishing coves. The samples were analysed by enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) techniques. The results show that, of the total number of persons studied, 100% were negative for Trypanosoma cruzi Chagas (Trypanosomatida: Trypanosomatidae) antibodies, 10.34% of canids were positive for the antibody and 5.8% of M. gajardoi were infected to the PCR technique. The presence of this species in areas close to human settlements constitutes a risk to human populations established on the coast of northern Chile.

  11. Dating upper plate normal fault slip events in Late Pleistocene and Holocene sediments of northern Chile

    Science.gov (United States)

    Robinson, R. A.; Binnie, S.; Gonzalez, G.; Cortés, J.

    2011-12-01

    In order to understand how subduction earthquakes along the Nazca-South America plate boundary affect upper plate faults in the coastal forearc of northern Chile, we are developing the first detailed paleoseismological study to characterize the Late Quaternary activity of the Mejillones and Salar del Carmen faults, located around 40 km north and 15 km east of Antofagasta, respectively. There is currently a lack of basic palaeo-seismological data on these and other upper plate faults, such as long term slip rates, amount of slip per event, palaeo-earthquake magnitude and recurrence intervals. This lack of knowledge impedes understanding of how large subduction earthquakes, occurring at depths of around 50 km in this region, relate to upper plate seismicity and deformation. We have used OSL dating of fault-related sediments, and cosmogenic-ray nuclide dating of terrace surfaces, to constrain slips rates over the last 45 ka. Several trenches were excavated across both faults in order to expose and log the most recent fault-related sediments. In the hanging wall of these normal faults, vertically stacked colluvial wedges and hillslope deposits are the product of discrete slip events and post-slip fault scarp degradation. Multiple trenches along each fault permit the spatial variability in slip amount and fault-related sedimentation to be investigated. Long-term slip rates have been measured using cosmogenic-ray nuclide exposure dating of the alluvial terraces offset by the Mejillones Fault. OSL dating of the fault-related sediments in the trenches has been used to compare the ages of individual slip events on both faults, and the age of events recorded along the trace of each fault. The application of both cosmogenic-ray nuclide and OSL methods in this type of setting (hyper-arid with low erosion rates, yet tectonically active) is non-trivial, due to cosmogenic inheritance accumulated in cobbles on the terrace surfaces, low sensitivity of the quartz for OSL dating, and

  12. 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

  13. Interseismic Rates From the CTO cGPS Andes and Nepal Networks

    Science.gov (United States)

    Genrich, J. F.; Galetzka, J.; Chowdhury, F.; Avouac, J.; Simons, M.; Barrientos, S. E.; Comte, D.; Norabuena, E. O.; Sapkota, S. N.

    2009-12-01

    To study crustal deformation at converging plate margins the Caltech Tectonics Observatory (CTO), together with partner institutions in the host countries, operates continuously observing GPS stations in the central Andes (northern Chile and southern Peru) and in Nepal. The currently 20-site Andes network was established in 2005 with 7 stations. Efforts are underway to provide data streaming links at near real time for the majority of sites. The Nepal network started with 10 sites in 2004 and has been expanded to 23 sites in the last couple of years. Dual frequency code and phase data from all sites are processed with the GAMIT/GLOBK processing package. Reliable interseismic velocities are now available for the majority of sites. Network metadata, rinex data files, processed time series and velocity estimates can be found online thru links at the CTO website: tectonics.caltech.edu.

  14. 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

  15. Diversidad de la familia Carabidae (Coleoptera en Chile Diversity of the family Carabidae (Coleoptera in Chile

    Directory of Open Access Journals (Sweden)

    SERGIO ROIG-JUÑENT

    2001-09-01

    Full Text Available Carabidae constituye dentro de los coléopteros chilenos, la cuarta familia en importancia por su cantidad de especies. El presente trabajo incluye una breve compilación acerca de la historia de la familia y de las primeras expediciones realizadas en Chile. También se realizan comparaciones de la diversidad de carábidos chilenos con respecto a otros países y el Neotrópico. Para Chile, se conocen 21 tribus, con 95 géneros y 365 especies, que representan el 38,8, 28,8 y 7,9 % de la fauna del Neotrópico, respectivamente. Chile posee un bajo número de tribus comparado con otros países, sin embargo, constituye un área importante por la presencia de seis tribus relictuales, principalmente pangeicas o gondwánicas. Chile posee 18 géneros endémicos (18,5 % de su fauna de Carabidae, 28 cuya distribución está restringida a Chile y Argentina y seis restringidos a Chile, Argentina y Uruguay. La cantidad de especies presentes en Chile es inferior a la que poseen otros países de América del Sur, pero la cantidad de especies endémicas es muy alta (204 y representa el 55,8 % de su fauna de carábidos. El alto grado de endemismo que posee Chile con respecto a otros países de América del Sur puede deberse a su condición de aislamiento, siendo las barreras más importantes la región desértica del norte y la cordillera de Los Andes. Este hecho también se vislumbra por la ausencia de importantes tribus neotropicales como Galeritini, Scaritini y Brachinini. También se incluyen en este trabajo claves para la identificación de todas las tribus y géneros presentes en Chile, como así también una breve descripción acerca de la diversidad y ambientes en los que se encuentra cada géneroThe family Carabidae is the fourth largest Coleoptera family in Chile. The present work includes a brief compilation on the taxonomic history of the family and the first expeditions to Chile. In addition, knowledge of carabid diversity in Chile is compared with

  16. 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.

  17. Memorias del paisaje cordillerano: la travesía de los Andes en la Gobernación de Chile durante el siglo XVIII

    Directory of Open Access Journals (Sweden)

    Alejandra Vega Palma

    2012-07-01

    Full Text Available En el presente artículo se analizan diferentes escritos del siglo XVIII para relevar la herencia multisecular de un imaginario asociado a los peligros del cruce cordillerano, que atraviesa transformaciones políticas y culturales de envergadu-ra. La noción de peligro, y el temor asociado al mismo, se despliega en los textos que informan o describen la travesía de la cordillera en el Reino de Chile, apelando a las amenazas de caer en el abismo o de congelarse de frío. Los ecos de estas marcas, establecidas tempranamente en la cultura colonial de Chile, se pueden rastrear también en los llamados escritos ilustrados, en que estos tópicos se funden con los de la montaña sublime.

  18. 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

  19. 50 years of water extraction in the Pampa del Tamarugal basin: Can Prosopis tamarugo trees survive in the hyper-arid Atacama Desert (Northern Chile)?

    NARCIS (Netherlands)

    Chávez Oyanadel, R.O.; Clevers, J.G.P.W.; Decuyper, M.; Bruin, de S.; Herold, M.

    2016-01-01

    Groundwater-dependent ecosystems are threatened worldwide by unsustainable groundwater (GW) extraction. This is the case of the Prosopis tamarugo Phil forest in the hyper-arid Atacama Desert (Northern Chile), one of the most extreme ecosystems on Earth. Despite concerns about the conservation of thi

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. "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”.

  6. First identification of azaspiracid and spirolides in Mesodesma donacium and Mulinia edulis from Northern Chile.

    Science.gov (United States)

    Alvarez, Gonzalo; Uribe, Eduardo; Avalos, Paulo; Mariño, Carmen; Blanco, Juan

    2010-01-01

    In an attempt to evaluate the risk for human consumption associated to the accumulation of lipophilic toxins by two commercially important bivalves: macha (Mesodesma donacium) and clam (Mulinia edulis) in Coquimbo Bay (Chile), monitoring of these species was carried out from March to September 2008. The samples were analyzed by liquid chromatography-mass spectrometry (LC-MS) to detect okadaic acid, dinophysistoxins, pectenotoxins, azaspiracids, yessotoxins and spirolides. Low levels of Azaspiracid-1 and 13-desmethyl C spirolide were found in both species. The toxins were detected at different dates throughout the monitoring period and in some cases both toxins were detected in the same sample. In all cases, the concentration of the toxins was below the limit of quantification of the technique used and therefore these detections are only indicative of a potential risk. This is the first report of the occurrence of these groups of toxins in Chile and suggests that it is necessary to monitor routinely these substances to warrant public health and shellfish exportations. PMID:19631679

  7. A dichotomous species of Codium (Bryopsidales, Chlorophyta is colonizing northern Chile Una especie dicotómica de Codium (Bryopsidales, Chlorophyta está colonizando el norte de Chile

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    ALEJANDRA GONZÁLEZ

    2004-06-01

    Full Text Available In late 2001 and early 2002, a dichotomous species of Codium appeared colonizing the low intertidal and shallow subtidal bottoms of Caldera Bay, northern Chile (27° 03’ S, 70° 51’ W. Due to the ecological and economic impact the species is having in Caldera Bay and its potential spread along the Chilean coastline, we studied the taxonomic identity of the species and examined its relationships with other dichotomous species of Codium reported for temperate Pacific South America. Morphological analyses suggest that the seaweeds from Caldera Bay belong to Codium fragile (Suringar Hariot. Not only is there strong agreement in internal and external morphological characters, but among all the species reported for Peru and Chile, this is the only one exhibiting utricles with rounded, apiculate tip terminating in a mucron. This species has a broad geographic distribution in temperate waters. In Chile it was known only from the coasts of Valdivia to the Straits of Magellan (39° 48’ S, 73° 26’ W to 53° 10’ S, 73° 49’ W. This is the first record of C. fragile in northern Chile, and this study discusses several alternative hypotheses for the presence of the species into this area. The morphological characteristics of the material collected in Caldera partially agree with diagnostic characters known for C. fragile subspecies tasmanicum and C. fragile subspecies tomentosoides. However, the rapid population spread of the species in northern Chile, and recent molecular analysis support the identification of this form as the invasive C. fragile subspecies tomentosoidesA fines de 2001 y principio de 2002, apareció en el norte de Chile una especie del género Codium, de morfología dicotómica, colonizando los niveles intermareales y submareales de la Bahía de Caldera (27° 03’ S, 70° 51’ O. Debido al impacto ecológico y económico que ha provocado esta especie en la Bahía de Caldera y a su dispersión potencial a lo largo de la costa de

  8. Habitat characteristics influence macrofaunal communities in coralline turf more than mesoscale coastal upwelling on the coast of Northern Chile

    Science.gov (United States)

    Kelaher, Brendan P.; Carlos Castilla, Juan

    2005-04-01

    Rocky shore communities are often influenced by near-shore coastal upwelling. For macrofauna in algal turf, these effects may be caused directly by well-studied bottom-up mechanisms or indirectly via changes in habitat structure provided by algal turf associated high nutrient loads. Here, we investigated possible interactions between upwelling and habitat structure by sampling diverse faunal assemblages in coralline algal turf on seven rocky intertidal shores in northern Chile, ranging from El Cobre [23°17'1″S, 70°31'40″W] to La Lobería [23°03'40″S, 70°33'14″W]. Some of these shores were located adjacent to strong upwelling centers, while others were in areas rarely affected. On each shore, we sampled four (2 × 2 m) sites separated by 15-50 m. In each site, we collected three replicate cores (80 mm in diameter) from which we measured macrofauna greater than 850 μm, biomass of sediment and epiphytes, frond density and average frond length. We used mean water temperature and its variation at 1-1.5 m water depth (below Extreme Low Water Spring, ELWS) to represent local upwelling intensity because long-term data have shown that these variables make excellent indicators for this region. In total, we found 94 macrofaunal taxa in coralline turf, which is almost three times higher than has previously been reported in Chile. Although macrofaunal assemblages varied significantly among shores, there were no patterns to suggest mesoscale variation in upwelling intensity affected either faunal assemblages or local habitat characteristics. In contrast, multivariate and univariate correlations highlighted sediment and frond density as strong determinants of community structure. We therefore conclude that traditionally studied habitat characteristics, such as structural complexity and habitat heterogeneity, have greater influence on faunal assemblages in mat-like habitats on rocky shores than environmental variables associated with mesoscale coastal upwelling.

  9. 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.

  10. 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).

  11. Late Pleistocene human occupation of the hyperarid core in the Atacama Desert, northern Chile

    Science.gov (United States)

    Latorre, Claudio; Santoro, Calogero M.; Ugalde, Paula C.; Gayo, Eugenia M.; Osorio, Daniela; Salas-Egaña, Carolina; De Pol-Holz, Ricardo; Joly, Delphine; Rech, Jason A.

    2013-10-01

    Few archeological sites in South America contain uncontroversial evidence for when the first peopling of the continent occurred. Largely ignored in this debate, extreme environments are assumed either as barriers to this early wave of migration or without potential for past habitability. Here, we report on a rare 12-13 ka human occupation from Quebrada Maní (site QM12), a plantless, near rainless landscape (1240 m asl and 85 km from the Pacific Ocean) located in the hyperarid core of the Atacama Desert. This location harbored wetlands and riparian woodlands that were fed by increased rainfall further east in the central Andes during the latest Pleistocene. Excavations at QM12 yielded a diverse cultural assemblage of lithics, burned and cut bones, marine gastropods, pigments, plant fibers, and wooden artifacts alongside a prepared fireplace. Sixteen radiocarbon dates from site QM12 on charcoal, marine shells, animal dung, plant remains and wood reveal that the occupation took place between 12.8 and 11.7 ka. These results demonstrate that the Atacama Desert was not a barrier to early American settlement and dispersal, and provide new clues for understanding the cultural complexity and diversity of the peopling of South America during the Last Glacial-interglacial transition.

  12. 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...

  13. 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

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    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

  14. 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.

  15. 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.

  16. 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...

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

    Science.gov (United States)

    Jorquera, Héctor; 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(10) and PM(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(10) and PM(2.5) were taken with Harvard Impactors; samples were analyzed by X Ray Fluorescence, ionic chromatography (NO(3)(-) and SO(4)(=)), 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 PM(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(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(10) is 50 μg/m(3) and the peak daily value is 104 μg/m(3). For the PM(2.5) fraction, suspended soil dust contributes with an average of 9.3

  18. 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

  19. Groundwater flow in a closed basin with a saline shallow lake in a volcanic area: Laguna Tuyajto, northern Chilean Altiplano of the Andes.

    Science.gov (United States)

    Herrera, Christian; Custodio, Emilio; Chong, Guillermo; Lambán, Luis Javier; Riquelme, Rodrigo; Wilke, Hans; Jódar, Jorge; Urrutia, Javier; Urqueta, Harry; Sarmiento, Alvaro; Gamboa, Carolina; Lictevout, Elisabeth

    2016-01-15

    Laguna Tuyajto is a small, shallow saline water lake in the Andean Altiplano of northern Chile. In the eastern side it is fed by springs that discharge groundwater of the nearby volcanic aquifers. The area is arid: rainfall does not exceed 200mm/year in the rainiest parts. The stable isotopic content of spring water shows that the recharge is originated mainly from winter rain, snow melt, and to a lesser extent from some short and intense sporadic rainfall events. Most of the spring water outflowing in the northern side of Laguna Tuyajto is recharged in the Tuyajto volcano. Most of the spring water in the eastern side and groundwater are recharged at higher elevations, in the rims of the nearby endorheic basins of Pampa Colorada and Pampa Las Tecas to the East. The presence of tritium in some deep wells in Pampa Colorada and Pampa Las Tecas indicates recent recharge. Gas emission in recent volcanoes increase the sulfate content of atmospheric deposition and this is reflected in local groundwater. The chemical composition and concentration of spring waters are the result of meteoric water evapo-concentration, water-rock interaction, and mainly the dissolution of old and buried evaporitic deposits. Groundwater flow is mostly shallow due to a low permeability ignimbrite layer of regional extent, which also hinders brine spreading below and around the lake. High deep temperatures near the recent Tuyajto volcano explain the high dissolved silica contents and the δ(18)O shift to heavier values found in some of the spring waters. Laguna Tuyajto is a terminal lake where salts cumulate, mostly halite, but some brine transfer to the Salar de Aguas Calientes-3 cannot be excluded. The hydrogeological behavior of Laguna Tuyajto constitutes a model to understand the functioning of many other similar basins in other areas in the Andean Altiplano.

  20. Trauma in the preceramic coastal populations of northern Chile: violence or occupational hazards?

    Science.gov (United States)

    Standen, V G; Arriaza, B T

    2000-06-01

    One hundred and forty-four Chinchorro skeletons, stored at the Museo Arqueol¿ogico San Miguel de Azapa in Arica, Chile, were examined to test the following alternative hypotheses concerning skeletal trauma: either observed trauma was a consequence of interpersonal violence, or was the result of work-related accidents. Trauma found in subadults was rare, with 1.8% (1/55) contrasted with 30% (27/89) in the adult population. The location of most adult trauma was the skull with 24.6% (17/69), followed by the upper extremities with 8. 7% (7/80), the trunk with 2.9% (2/68), and the lower extremities with the least trauma at 1.1% (1/89). Skull trauma corresponded to well-healed, semicircular fractures, with males being three times more affected than females at 34.2% (13/38) and 12.9% (4/31), respectively. Most fractures were nonlethal, appearing to have been caused by impacts from stones, suggesting interpersonal violence rather than accidents. This study indicates that the egalitarian, maritime, hunter-gatherer Chinchorro culture (circa 4000 years B.P.) may not have lived as peacefully as once thought.

  1. 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.

  2. Case-control study of arsenic in drinking water and kidney cancer in uniquely exposed Northern Chile.

    Science.gov (United States)

    Ferreccio, Catterina; Smith, Allan H; Durán, Viviana; Barlaro, Teresa; Benítez, Hugo; Valdés, Rodrigo; Aguirre, Juan José; Moore, Lee E; Acevedo, Johanna; Vásquez, María Isabel; Pérez, Liliana; Yuan, Yan; Liaw, Jane; Cantor, Kenneth P; Steinmaus, Craig

    2013-09-01

    Millions of people worldwide are exposed to arsenic in drinking water. The International Agency for Research on Cancer has concluded that ingested arsenic causes lung, bladder, and skin cancer. However, a similar conclusion was not made for kidney cancer because of a lack of research with individual data on exposure and dose-response. With its unusual geology, high exposures, and good information on past arsenic water concentrations, northern Chile is one of the best places in the world to investigate the carcinogenicity of arsenic. We performed a case-control study in 2007-2010 of 122 kidney cancer cases and 640 population-based controls with individual data on exposure and potential confounders. Cases included 76 renal cell, 24 transitional cell renal pelvis and ureter, and 22 other kidney cancers. For renal pelvis and ureter cancers, the adjusted odds ratios by average arsenic intakes of 1,000 µg/day (median water concentrations of 60, 300, and 860 µg/L) were 1.00, 5.71 (95% confidence interval: 1.65, 19.82), and 11.09 (95% confidence interval: 3.60, 34.16) (Ptrend water arsenic causes renal pelvis and ureter cancer.

  3. The emplacement of the granitic Las Tazas complex, northern Chile: the relationship between local and regional strain

    Science.gov (United States)

    Wilson, Jeff; Grocott, John

    1999-11-01

    The Coastal batholith of northern Chile grew under transtensional-extensional conditions that prevailed along the Andean margin during the Mesozoic. The batholith hosts the Atacama Fault Zone, a major arc-parallel fault system which was characterised by sinistral transtensional shearing during the Early Cretaceous. The Las Tazas complex is a composite granitoid intrusion that was emplaced syntectonically along the Atacama Fault Zone at ˜130 Ma. Syntectonic emplacement is indicated by a consistent kinematic history between the complex and its wall rocks, together with synchronous crystallisation and shearing ages. In contrast to regional patterns, the Las Tazas complex was emplaced during a local change from vertical east-side-down to dextral transcurrent displacement along the fault zone. During intrusion, strain was partitioned between non-coaxial simple shearing within country-rock mylonites and a flattening strain across the crystallising complex. This combination indicates that the pluton was emplaced under temporary transpressive conditions that were localised around the pluton, probably induced by magma emplacement. Such a difference between local and regional strain suggests that emplacement-related structures should only be related to regional strain-states with great care.

  4. Structural characteristics of an active fold-and-thrust system in the southeastern Atacama Basin, northern Chile

    Science.gov (United States)

    Lin, Yen-Sheng; Chuang, Yi-Rung; Shyu, J. Bruce H.; González, Gabriel; Shen, Chuan-Chou; Lo, Ching-Hua; Liou, Ya-Hsuan

    2016-08-01

    The western South American margin is one of the most active plate boundaries in the world. Using various remote sensing data sets, we mapped the neotectonic characteristics of an area at the southeastern corner of the Atacama Basin, northern Chile, in the Andean forearc. There, one major N-S trending ridge is clearly visible both in the satellite images and in the field. This ridge reaches 250 m above the basin floor in its middle part and is asymmetrical, with a steep eastern slope and a much gentler western slope. The geometry of the ridge indicates that it formed as an asymmetrical anticline. This anticline is likely formed as a shear fault-bend fold, with a major décollement at a depth of about 2.5 km in the Naranja Formation. We suggest that this décollement is a major structure of the Atacama Basin area. From the ages of the ignimbrites and lake deposits that were deformed by this anticline, we obtained a long-term shortening rate of the major underlying structure at about 0.2 mm/yr. This thin-skinned fold-and-thrust system appears to be active since at least about 3 Ma, and could be as long as since middle Miocene. Therefore, crustal structures may play important roles in the Neogene development of the western Andean margin.

  5. Analysis of subsurface temperature data to quantify groundwater recharge rates in a closed Altiplano basin, northern Chile

    Science.gov (United States)

    Kikuchi, C. P.; Ferré, T. P. A.

    2016-09-01

    Quantifying groundwater recharge is a fundamental part of groundwater resource assessment and management, and is requisite to determining the safe yield of an aquifer. Natural groundwater recharge in arid and semi-arid regions comprises several mechanisms: in-place, mountain-front, and mountain-block recharge. A field study was undertaken in a high-plain basin in the Altiplano region of northern Chile to quantify the magnitude of in-place and mountain-front recharge. Water fluxes corresponding to both recharge mechanisms were calculated using heat as a natural tracer. To quantify in-place recharge, time-series temperature data in cased boreholes were collected, and the annual fluctuation at multiple depths analyzed to infer the water flux through the unsaturated zone. To quantify mountain-front recharge, time-series temperature data were collected in perennial and ephemeral stream channels. Streambed thermographs were analyzed to determine the onset and duration of flow in ephemeral channels, and the vertical water fluxes into both perennial and ephemeral channels. The point flux estimates in streambeds and the unsaturated zone were upscaled to channel and basin-floor areas to provide comparative estimates of the range of volumetric recharge rates corresponding to each recharge mechanism. The results of this study show that mountain-front recharge is substantially more important than in-place recharge in this basin. The results further demonstrate the worth of time-series subsurface temperature data to characterize both in-place and mountain-front recharge processes.

  6. Young displacements on the Atacama Fault System, northern Chile from field observations and cosmogenic 21Ne concentrations

    Science.gov (United States)

    GonzáLez L., Gabriel; Dunai, Tibor; Carrizo, Daniel; Allmendinger, Richard

    2006-06-01

    We present the first numerical age constraint for young deformation of the Atacama Fault System (AFS) in northern Chile. The young activity of the AFS is expressed by several fault scarps which affects alluvial fan sediments of the eastern side of the Coastal Cordillera (23°30'-23°42'S). Detailed mapping of alluvial fans reveals a complex relationship between fault motion, erosion and alluvial fan development. An older group of alluvial fans became inactive prior to the scarp formation. Younger alluvial fans, arising directly from feeder channels and entrenched in the fault scarps, posts date the scarp formation. The youngest slip on the AFS is recorded by headward eroding channels entrenched across the scarp which are in turn displaced vertically 0.3-0.5 m by the fault. Quartz fragments in four sites on the older inactive fan group were analyzed for cosmogenic 21Ne concentrations yielding an average age of 424 ± 151 ka, the upper limit for the recent activity of the fault. Combined with the height of fault scarp, we calculate a 0.01 mm/yr minimum vertical fault slip rate. Thus young displacement on the AFS is Quaternary in age and confined to the late Pleistocene.

  7. 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).

  8. 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.

  9. Case-Control Study of Arsenic in Drinking Water and Kidney Cancer in Uniquely Exposed Northern Chile

    Science.gov (United States)

    Ferreccio, Catterina; Smith, Allan H.; Durán, Viviana; Barlaro, Teresa; Benítez, Hugo; Valdés, Rodrigo; Aguirre, Juan José; Moore, Lee E.; Acevedo, Johanna; Vásquez, María Isabel; Pérez, Liliana; Yuan, Yan; Liaw, Jane; Cantor, Kenneth P.; Steinmaus, Craig

    2013-01-01

    Millions of people worldwide are exposed to arsenic in drinking water. The International Agency for Research on Cancer has concluded that ingested arsenic causes lung, bladder, and skin cancer. However, a similar conclusion was not made for kidney cancer because of a lack of research with individual data on exposure and dose-response. With its unusual geology, high exposures, and good information on past arsenic water concentrations, northern Chile is one of the best places in the world to investigate the carcinogenicity of arsenic. We performed a case-control study in 2007–2010 of 122 kidney cancer cases and 640 population-based controls with individual data on exposure and potential confounders. Cases included 76 renal cell, 24 transitional cell renal pelvis and ureter, and 22 other kidney cancers. For renal pelvis and ureter cancers, the adjusted odds ratios by average arsenic intakes of 1,000 µg/day (median water concentrations of 60, 300, and 860 µg/L) were 1.00, 5.71 (95% confidence interval: 1.65, 19.82), and 11.09 (95% confidence interval: 3.60, 34.16) (Ptrend < 0.001), respectively. Odds ratios were not elevated for renal cell cancer. With these new findings, including evidence of dose-response, we believe there is now sufficient evidence in humans that drinking-water arsenic causes renal pelvis and ureter cancer. PMID:23764934

  10. Reinterpretation of the Ordovician rotations in NW Argentina and Northern Chile: a consequence of the Precordillera collision?

    Science.gov (United States)

    Spagnuolo, Cecilia M.; Rapalini, Augusto E.; Astini, Ricardo A.

    2011-04-01

    Early Paleozoic paleomagnetic data from NW Argentina and Northern Chile have shown large systematic rotations within two domains: one composed of the Western Puna that yields very large (up to 80°) counter-clockwise rotations, and the other formed by the Famatina Ranges and the Eastern Puna that shows (~40°) clockwise rotations around vertical axes. In several locations, lack of significant rotations in younger rocks constrains this kinematic pattern to have occurred during the Paleozoic. Previous tectonic models have explained these rotations as indicative of rigid-body rotations of large para-autochthonous crustal blocks or terranes. A different but simple tectonic model that accounts for this pattern is presented in which rotations are associated to crustal shortening and tectonic escape due to the collision of the allochthonous terrane of Precordillera in the Late Ordovician. This collision should have generated dextral shear zones in the back arc region of the convergent SW Gondwana margin, where systematic domino-like clockwise rotations of small crustal blocks accommodate crustal shortening. The Western Puna block, bordering the Precordillera terrane to the north, might have rotated counterclockwise as an independent microplate due to tectonic escape processes, in a fashion similar to the present-day relationship between the Anatolia block and the Arabian microplate.

  11. 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

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

    Directory of Open Access Journals (Sweden)

    Pablo M Rojas

    2014-07-01

    Full Text Available 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 depth. The greatest accumulation of larvae was found in the middle layer (20-80 m, where the current velocity was low and did not interact with the circulation associated with upwelling the filament formation. Most fish larvae were found in non-upwelling waters in the middle stratum. Independent of the origin of water (upwelling/non-upwelling, larvae of Dioge-nichthys laternatus (Myctophidae, Engraulis ringens (Engraulidae and Bathylagus nigrigenys (Bathylagidae showed a deeper vertical distribution during the day, suggesting a daily vertical migration. This behavior can potentially increase retention of larvae near the coast in productive areas through vertical evasion of the Ekman layer during upwelling events.

  13. Chironomids as indicators of natural and human impacts in a 700-yr record from the northern Patagonian Andes

    Science.gov (United States)

    Williams, Natalia; Rieradevall, Maria; Añón Suárez, Diego; Rizzo, Andrea; Daga, Romina; Ribeiro Guevara, Sergio; Arribére, María Angélica

    2016-09-01

    Chironomid communities were studied in a sediment core collected from Lake Moreno Oeste, located in Nahuel Huapi National Park. A major change in midge assemblages occurred at ∼AD 1760, which was characterized by a decrease of "cold taxa" including Polypedilum sp.2 and Dicrotendipes, and an increase of "warm taxa" including Apsectrotanypus and Polypedilum sp.1. These taxa are likely related to climatic conditions concurrent with the end of a cold period at ∼AD 1500-1700 and the beginning of a drying climate at ∼AD 1740-1900 in northern Patagonia. Coarse tephra layers had low midge diversity; however they did not disrupt the climatic trend as the community recovered rapidly after the event. Since AD 1910, after the increase in suburban housing, fish introduction, and the construction of a road, there was an increase in the relative abundances of taxa typically associated with the littoral zone, such as Parapsectrocladius, Riethia, Apsectrotanypus, and some Tanytarsini morphotypes. The main change in the chironomid community appears to be associated with long-term climate change. At the beginning of the 20th century, other site-specific environmental factors (catchment change and fish introduction) altered the chironomid assemblages, making it more difficult to understand the relative importance of each driver of assemblage change.

  14. 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...

  15. 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

  16. Increased childhood liver cancer mortality and arsenic in drinking water in northern Chile.

    Science.gov (United States)

    Liaw, Jane; Marshall, Guillermo; Yuan, Yan; Ferreccio, Catterina; Steinmaus, Craig; Smith, Allan H

    2008-08-01

    Arsenic in drinking water is an established cause of lung, bladder, and skin cancers in adults and may also cause adult kidney and liver cancers. Some evidence for these effects originated from region II of Chile, which had a period of elevated arsenic levels in drinking water, in particular from 1958 to 1970. This unique exposure scenario provides a rare opportunity to investigate the effects of early-life arsenic exposure on childhood mortality; to our knowledge, this is the first study of childhood cancer mortality and high concentrations of arsenic in drinking water. In this article, we compare cancer mortality rates under the age of 20 in region II during 1950 to 2000 with those of unexposed region V, dividing subjects into those born before, during, or after the peak exposure period. Mortality from the most common childhood cancers, leukemia and brain cancer, was not increased in the exposed population. However, we found that childhood liver cancer mortality occurred at higher rates than expected. For those exposed as young children, liver cancer mortality between ages 0 and 19 was especially high: the relative risk (RR) for males born during this period was 8.9 [95% confidence interval (95% CI), 1.7-45.8; P = 0.009]; for females, the corresponding RR was 14.1 (95% CI, 1.6-126; P = 0.018); and for males and females pooled, the RR was 10.6 (95% CI, 2.9-39.2; P water during early childhood may result in an increase in childhood liver cancer mortality.

  17. Increased childhood liver cancer mortality and arsenic in drinking water in Northern Chile

    Science.gov (United States)

    Liaw, Jane; Marshall, Guillermo; Yuan, Yan; Ferreccio, Catterina; Steinmaus, Craig; Smith, Allan H.

    2009-01-01

    Arsenic in drinking water is an established cause of lung, bladder and skin cancers in adults, and may also cause adult kidney and liver cancer. Some evidence for these effects originated from Region II of Chile which had a period of elevated arsenic levels in drinking water, in particular from 1958 to 1970. This unique exposure scenario provides a rare opportunity to investigate the effects of early-life arsenic exposure on childhood mortality; to our knowledge, this is the first study of childhood cancer mortality and high concentrations of arsenic in drinking water. In this paper, we compare cancer mortality rates under the age of 20 in Region II during 1950–2000 with those of unexposed Region V, dividing subjects into those born before, during or after the peak exposure period. Mortality from the most common childhood cancers, leukemia and brain cancer, were not increased in the exposed population. However, we found childhood liver cancer mortality occurred at higher rates than expected; for those exposed as young children liver cancer mortality between ages 0–19 was especially high: the relative risk (RR) for males born during this period was 8.9 (95% CI 1.7–45.8; p=0.009), for females the corresponding RR was 14.1 (95% CI 1.6–126; p=0.018), and for males and females pooled, the RR was 10.6 (95% CI 2.9–39.2; p<0.001). These findings suggest exposure to arsenic in drinking water during early childhood may result in an increase in childhood liver cancer mortality. PMID:18708388

  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. Along-strike variations in post-seismic deformation in northern Chile and southern Peru

    Science.gov (United States)

    Pritchard, M. E.; Simons, M.

    2004-12-01

    We use InSAR and GPS data to constrain the spatio-temporal evolution of post-seismic after-slip following three large subduction zone earthquakes in South America. Post-seismic deformation following the 1995 {M}w~8.1 Antofagasta, Chile earthquake is barely above the InSAR detection limit, but by combining GPS observations with 36 interferograms we model the post-seismic deformation between the years 1995-2000. If the deformation is after-slip on the fault interface, the equivalent moment magnitude is 10-20% of the co-seismic moment, with the maximum deformation occurring 100 km from the maximum co-seismic slip. There is a pulse of deformation between large aftershocks in 1996 and 1998 that appears distinct from the general decay of after-slip with time. The low magnitude of post-seismic deformation is anomalous compared to other recent subduction zone earthquakes, including the nearby 2001 {M}w~8.4 Arequipa, Peru earthquake. After-slip following the 2001 earthquake between 2001-2004 equals about 20-40% of the co-seismic moment. There is no definitive post-seismic deformation following the 1996 {M}w~7.7 Nazca, Peru earthquake between 1997-1999, although there is no data spanning the first 51 days after the earthquake. Variations in the depth of rupture during these three earthquakes cannot solely explain the variations in after-slip. We suggest that variations in sediment subducted in each location may control the magnitude of after-slip. The larger thickness of sediments in the region of the 2001 earthquake might also explain why observed after-slip is located in the same area as the co-seismic slip, instead of down-dip, as in other subduction zones.

  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. 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...

  3. The Punta del Cobre Formation, Punta del Cobre Candelaria area, northern Chile

    Science.gov (United States)

    Marschik, Robert; Fontboté, Lluís.

    2001-09-01

    The Punta del Cobre Formation hosts the iron oxide-rich Cu-Au(-Zn-Ag) deposits of the Punta del Cobre belt, Chile. Hydrothermal alteration associated with mineralization and/or contact metamorphism caused by the Coastal Batholith exposed in the west resulted in new mineral assemblages and significant changes in the geochemical composition of its rocks. This paper presents a redefinition of the Punta del Cobre Formation and discusses its geologic context. The Punta del Cobre Formation is subdivided, from bottom to top, into: (1) the 'Geraldo-Negro Member', composed mainly of massive andesitic volcanic rocks (>300 m) and locally dacitic rocks (up to 200 m) that overlie the latter, and (2) the 'Algarrobos Member' (up to >800 m) comprising mainly volcaniclastic rocks, basalt andesitic and basaltic flows, and volcanic breccias. The Punta del Cobre Formation is overlain by the Chañarcillo Group, the lowest part of which is represented by alternating carbonate and volcaniclastic beds of the Abundancia Formation, which pass vertically and laterally into limestones of the Nantoco Formation. The contact between the Punta del Cobre Formation and the overlying Abundancia Formation is transitional and defined by the first continuous bed of massive limestone or its metamorphosed equivalent. A pre-upper Valanginian age for the Punta del Cobre Formation is suggested by ammonites of Berriasian age found in the upper part of the Algarrobos Member and Late Valanginian-Early Hauterivian fauna in the overlying Abundancia Formation. Despite the intense alteration, immobile element compositions of the volcanic rocks of the Punta del Cobre Formation enable the recognition of a calc-alkaline suite with a trend to more primitive, less differentiated magmas towards the top of the stratigraphic sequence, reflecting initial stages of basin development. The transgressive nature of the sedimentary part of the Punta del Cobre Formation marks the onset of increased subsidence that eventually

  4. 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

  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. Motion on upper-plate faults during subduction zone earthquakes: Case of the Atacama Fault System, northern Chile

    Science.gov (United States)

    Loveless, J. P.; Pritchard, M. E.

    2008-12-01

    Motion on the Atacama Fault System (AFS) in northern Chile is driven by Andean subduction zone processes. We use two approaches, observational and theoretical, to evaluate how the AFS and other forearc faults responded to coseismic stress induced by one well-studied megathrust earthquake, the 1995 Mw = 8.1 Antofagasta event. We use synthetic aperture radar interferometry (InSAR) to search for small-scale coseismic and postseismic deformation on individual faults. The InSAR data are ambiguous: some images show offset consistent with coseismic faulting on the Paposo segment of the AFS and others lack such signal. The fact that we do not observe the fault-like displacement in all coseismic interferograms suggests that atmospheric contamination, not tectonic deformation, is responsible for the signal. To explore the capacity of the earthquake to trigger motion on upper plate faults, we use seven published slip maps constrained by geodetic and/or seismic data to calculate static and dynamic Coulomb stress change (CSC) on faults in the Antofagasta region. The static CSC field varies between models and depends on the distribution of coseismic interplate slip. On the basis of the CSC distribution predicted by our preferred model constrained by all available data, we suggest it was unlikely that the Antofagasta earthquake directly triggered normal motion on the AFS, and the InSAR data are consistent with this null result. Field reports of normal faulting related to the earthquake may reflect recent (but not coseismic) motion or highly localized behavior not representative of the regional coseismic stress field.

  8. Hydrothermal alteration in an exhumed crustal fault zone: geochemical mobility in the Caleta Coloso Fault, Atacama Fault System, Northern Chile

    Science.gov (United States)

    Arancibia, G.; Fujita, K.; Hoshino, K.; Mitchell, T. M.; Cembrano, J. M.; Gomila, R.; Morata, D.; Faulkner, D. R.; Rempe, M.

    2013-12-01

    Fault zones must be considered as complex and heterogeneous systems, with areas of high permeability that alternate with very low permeability bands. Strike-slip fault zones play an important role in fluid migration in the crust, and exhumed faults can provide insights into the interrelationships of deformation mechanisms, fluid-rock interactions and bulk chemical redistributions. We determined the mineral chemistry and whole-rock geochemistry of the damage zone and fault core of the Caleta Coloso Fault, a complex major crustal scale strike-slip fault in Northern Chile, in order to constrain the physical and chemical conditions of fluids that lead to strong hydrothermal alteration. Caleta Coloso Fault consists of variably altered protocataclasites, cataclasites and discrete bands of ultracataclasite derived from a protolith of Jurassic tonalite. Hydrothermal alteration associated with fault-related fluid flow is characterized by a very low-grade association composed by chlorite, epidote, albite, quartz and calcite. Chlorite thermometry indicates T-values in the range of 284 to 352 °C (average temperature of 323 °C) and no differences in mineral composition or T-values were observed among different cataclastic rock types. Mass balance and volume change calculations document that the major chemical mobility was observed in protocataclasite, whereas cataclasite and ultracataclasite show smaller changes. This suggests that fluid flow and chemical alteration post-dated the faulting, when the protocataclasite was relatively permeable and the cataclasite and ultracataclasite acted as a barrier for fluid flow having a very low permeability due to extreme grain size reduction during cataclasis.

  9. SO2-flux measurements and BrO/SO2 ratios at Guallatiri volcano, Altiplano, northern Chile

    Science.gov (United States)

    Gliss, Jonas; Stebel, Kerstin; Thomas, Helen

    2015-04-01

    Sulphur dioxide (SO2) fluxes were measured recently at Guallatiri volcano using two UV SO2-cameras and one IR SO2-camera. Furthermore, measurements of reactive halogens (e.g. BrO, OClO) were investigated using a high performance DOAS (Differential Optical Absorption Spectroscopy) instrument. Guallatiri (18° 25' 00″ S, 69° 5' 30″ W, 6.071 m a.s.l.) is situated in the Altiplano in northern Chile, close to the Bolivian border. The last known eruption of Guallatiri was in 1960. The measurements were performed during a short-term field trip on three days in November 2014 (20.11.-22.11.2014). During that time, the volcano showed a quiescent degassing behaviour from the summit crater and from a fumarolic field on the southern flank. A preliminary evaluation of the spectra recorded with the DOAS instruments showed SO2 column amounts (SCDs) up to 3 - 1017 molec/cm2 and BrO-SCDs of the order of several 1013 molec/cm2. This corresponds to BrO/SO2-ratios of the order of 10-4 which is a typical order of magnitude for volcanic emissions. We will present SO2-flux estimates for Guallatiri volcano during these three days as well as BrO/SO2-ratio estimates in dependence of different plume ages. Furthermore, we will compare the results retrieved with the two UV-cameras with the data recorded simultaneously with the IR-camera.

  10. Latest Pleistocene and Holocene glacial events in the Colonia valley, Northern Patagonia Icefield, southern Chile

    Science.gov (United States)

    Nimick, David A.; Mcgrath, Daniel; Mahan, Shannon; Friesen, Beverly A.; Leidich, Jonathan

    2016-01-01

    The Northern Patagonia Icefield (NPI) is the primary glaciated terrain worldwide at its latitude (46.5–47.5°S), and constraining its glacial history provides unique information for reconstructing Southern Hemisphere paleoclimate. The Colonia Glacier is the largest outlet glacier draining the eastern NPI. Ages were determined using dendrochronology, lichenometry, radiocarbon, cosmogenic 10Be and optically stimulated luminescence. Dated moraines in the Colonia valley defined advances at 13.2 ± 0.95, 11.0 ± 0.47 and 4.96 ± 0.21 ka, with the last being the first constraint on the onset of Neoglaciation for the eastern NPI from a directly dated landform. Dating in the tributary Cachet valley, which contains an ice-dammed lake during periods of Colonia Glacier expansion, defined an advance at ca. 2.95 ± 0.21 ka, periods of advancement at 810 ± 49 cal a BP and 245 ± 13 cal a BP, and retreat during the intervening periods. Recent Colonia Glacier thinning, which began in the late 1800s, opened a lower-elevation outlet channel for Lago Cachet Dos in ca. 1960. Our data provide the most comprehensive set of Latest Pleistocene and Holocene ages for a single NPI outlet glacier and expand previously developed NPI glacial chronologies.

  11. 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

  12. 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

  13. Terral De Vicuna, a Foehnlike Wind in Semiarid Northern Chile: Meteorological Aspects and Implications for the Fulfillment of Chill Requirements in Deciduous Fruit Trees

    Science.gov (United States)

    Montes, Carlo; Rutllant, Jose A.; Aguirre, Anita; Bascunan-Godoy, Luisa; Julia, Cristobal

    2016-01-01

    The terral de Vicuña is a warm and dry wind that flows down the Elqui Valley in north-central Chile typically at dawn and early morning. Given that most terral episodes occur in austral winter when chill accumulation by deciduous fruit trees proceeds, negative effects on agriculture may be expected. During 11 (2004-14) winters a meteorological characterization of terral winds and the assessment of their impact on chill accumulation, by the modified Utah Model and the Dynamic Model, were performed. Within this period, 67 terral days (TD) were identified as those in which nighttime to early morning wind direction and speed, air temperature, and relative humidity reached defined thresholds on an hourly basis (terral hours). Most frequent TD featured 6-9 consecutive terral hours; duration is considered here as a proxy for their intensity. Synoptic-scale meteorological analysis shows that 65% of moderate and strong terral events develop as a cold, migratory anticyclone drifts poleward of the study area, coinciding with the onset of a midtropospheric ridge over central Chile, bringing southwest winds on top of the Andes (approximately 500-hPa level). The remaining 35% are either associated with 500-hPa easterlies (foehn like), with prefrontal conditions ahead of a trough driving northwest 500-hPa winds, or with transitional 500-hPa westerlies.Assessments of chill accumulation during TD show that, although present average and cold winter conditions do not represent a major TD hazard to local agriculture, lower chill accumulation associated with anomalously high nocturnal temperatures could be significantly more important during present and future warmer winters.

  14. 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

  15. 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.

  16. 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...

  17. Albedo changes, Milankovitch forcing, and late quaternary climate changes in the central Andes

    Energy Technology Data Exchange (ETDEWEB)

    Kull, C.; Grosjean, M. [Swiss Federal Inst. of Tech., Zurich (Switzerland). Dept. of Geography

    1998-11-01

    Late quaternary humidity changes resulted in substantial modifications of the land surface characteristics in the Altiplano of the Atacama desert, central Andes. Reconstructions of surface albedo, top-of-atmosphere (TOA) albedo, and shortwave net radiation in the Andes of northern Chile for 20,14,10,7 and 0 ka suggest that surface and TOA albedo increased substantially during periods of relatively humid environmental conditions (i.e., with large palaeolakes, glaciers and dense vegetation). The decrease of summer shortwave net radiation and seasonality during the late-glacial/early Holocene humid phase (14 to 10 ka) due to Earth`s surface and atmospheric characteristics added to the effect of orbitally driven negative deviations of southern Hemisphere austral summer insolation and minimum seasonality at 20 S. Therefore, in situ radiative forcing is, in contrast to the Northern Hemisphere tropics, not a suitable explanation for enhanced convective precipitation and, ultimately, humid climatic conditions. Our results suggest that late Quaternary humidity changes on the Altiplano reflect a collective response to (1) environmental changes in the source area of the moisture (e.g., reexpansion of the rain forest and increased release of latent heat over Amazonia and the Chaco, warm sea surface temperatures in the E Pacific) and, (2) large-scale circulation patterns and wave structures in the upper troposphere (strength and position of the Bolivian high, divergent flow stimulating convection over the Altiplano), or that they even reflect a response to (3) interhemispherical teleconnections. (orig.) With 5 figs., 2 tabs., 45 refs.

  18. Coupling between the environment and the pelagic resources exploited off northern Chile: ecosystem indicators and a conceptual model Acoplamiento entre el ambiente y los recursos pelágicos explotados en el norte de Chile: un modelo conceptual

    Directory of Open Access Journals (Sweden)

    Eleuterio Yáñez

    2008-01-01

    Full Text Available The eastern boundary of the Chile-Peru Current System constitutes one of the most biologically productive ecosystems in the world, due largely to coastal upwelling and the horizontal advection of nutrients. In this ecosystem, El Niño events are of great importance in the interannual variability of the environment. A change was observed in the environmental regime at the beginning of the 1970s with the onset of the 1972-1973 El Niño, marking an important decrease in the anchovy fishery (Engraulis ringens. After the mid-1970s, sardine (Sardinops sagax landings increased noticeably. A second regime shift at the end of the 1980s was seen mostly in the noticeable recovery of anchovy and the decline of sardine. Herein, we present an integrated conceptual model of the different local and large-scale phenomena that affect the marine environment off northern Chile and the distribution and abundance of pelagic resources. The model considers an analysis of environmental and bio-fishery data on different scales and describes how the interdecadal (associated with re-gime shifts and interannual (associated with El Niño events fluctuations in the Equatorial Pacific are mani-fested in the eastern South Pacific and, therefore, in the northern zone off Chile, affecting the annual eyele, the dynamic of the coastal trapped waves, and coastal upwelling. In this framework, interdecadal fluctuations play an important role in the anchovy-sardine-anchovy replacement sequence.El borde oriental del Sistema de Corrientes de Chile-Perú constituye uno de los ecosistemas de mayor productividad biológica del mundo, debido principalmente a la surgencia costera y advección horizontal de nutrientes. En este ecosistema, los eventos El Niño son de mayor importancia en la variabilidad interanual del ambiente. No obstante, un cambio de régimen ambiental es observado a inicio de los 70's el que hubiera comenzado con El Niño 1972-73 y que marca la gran disminución de la

  19. 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.

  20. 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...

  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. 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.

  3. 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

  4. 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

  5. Hydrothermal alteration and magnetic properties of rocks in the Carolina de Michilla stratabound copper district, northern Chile

    Science.gov (United States)

    Townley, Brian; Roperch, Pierrick; Oliveros, Verónica; Tassara, Andres; Arriagada, César

    2007-10-01

    In the Carolina de Michilla district, northern Chile, stratabound copper mineralization is hosted by Jurassic volcanic rocks along the trace of the Atacama fault system. In this study, we present the overall effects of hydrothermal alteration on the magnetic properties of rocks in this district. Two types of metasomatic alteration associations occur, one of regional extent and the other of local hydrothermal alteration associated with copper mineralization (e.g., Lince Estefanía Susana). Regional alteration is interpreted as a low-grade “propylitic association” characterized by an epidote chlorite smectite titanite albite quartz calcite association. The local hydrothermal alteration is characterized broadly by a quartz albite epidote chlorite calcite mineral assemblage. The most pervasive alteration mineral is albite, followed by epidote and, locally, actinolite. These minerals contrast sharply against host rock minerals such as chlorite, calcite, zeolite, prehnite, and pumpellyite, but alteration is constrained to mineralized bodies as narrow and low contrast alteration halos that go outwards from actinolite albite to epidote albite, to epidote chlorite, and finally to chlorite. Hydrothermal alteration minerals, compared to regional alteration minerals, show iron-rich epidotes, a lower chlorite content of the chlorite smectite series, and a nearly total albite replacement of plagioclase in the mineralized zones. Opaque minerals associated with regional alteration are magnetite and maghemite, and those associated to hydrothermal alteration are magnetite, hematite, and copper sulphides. We present paleomagnetic results from nine sites in the Michilla district and from drill cores from two mines. Local effects of hydrothermal alteration on the original magnetic mineralogy indicate similar characteristics and mineralogy, except for an increase of hematite that is spatially associated with the Cu sulphide breccias with low magnetic susceptibilities. Results

  6. Double seismic zone of the Nazca plate in northern Chile: High-resolution velocity structure, petrological implications, and thermomechanical modeling

    Science.gov (United States)

    Dorbath, Catherine; Gerbault, Muriel; Carlier, Gabriel; Guiraud, Michel

    2008-07-01

    This paper presents an interdisciplinary study of the northern Chile double seismic zone. First, a high-resolution velocity structure of the subducting Nazca plate has been obtained by the tomoDD double-difference tomography method. The double seismic zone (DSZ) is observed between 80 and 140 km depth, and the two seismic planes is 20 km apart. Then, the chemical and petrologic characteristics of the oceanic lithosphere associated with this DSZ are deduced by using current thermal-petrological-seismological models and are compared to pressure-temperature conditions provided by a numerical thermomechanical model. Our results agree with the common hypothesis that seismicity in both upper and lower planes is related to fluid releases associated with metamorphic dehydration reactions. In the seismic upper plane located within the upper crust, these reactions would affect material of basaltic (MORB) composition and document different metamorphic reactions occurring within high-P (>2.4 GPa) and low-T (130 km), lawsonite-amphibole eclogite conditions. The lower plane lying in the oceanic mantle can be associated with serpentinite dehydration reactions. The Vp and Vs characteristics of the region in between both planes are consistent with a partially (˜25-30 vol % antigorite, ˜0-10% vol % brucite, and ˜4-10 vol % chlorite) hydrated harzburgitic material. Discrepancies persist that we attribute to complexities inherent to heterogeneous structural compositions. While various geophysical indicators evidence particularly cold conditions in both the descending Nazca plate and the continental fore arc, thermomechanical models indicate that both seismic planes delimit the inner slab compressional zone around the 400°C (±50°C) isotherm. Lower plane earthquakes are predicted to occur in the slab's flexural neutral plane, where fluids released from surrounding metamorphic reactions could accumulate and trigger seismicity. Fluids migrating upward from the tensile zone below

  7. 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

  8. 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

  9. 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

  10. Late Quaternary vegetation and climate history of a perennial river canyon in the Rīo Salado basin (22°S) of Northern Chile

    Science.gov (United States)

    Latorre, Claudio; Betancourt, Julio L.; Arroyo, Mary T.K.

    2006-01-01

    Plant macrofossils from 33 rodent middens sampled at three sites between 2910 and 3150 m elevation in the main canyon of the Rīo Salado, northern Chile, yield a unique record of vegetation and climate over the past 22,000 cal yr BP. Presence of low-elevation Prepuna taxa throughout the record suggests that mean annual temperature never cooled by more than 5°C and may have been near-modern at 16,270 cal yr BP. Displacements in the lower limits of Andean steppe and Puna taxa indicate that mean annual rainfall was twice modern at 17,520-16,270 cal yr BP. This pluvial event coincides with infilling of paleolake Tauca on the Bolivian Altiplano, increased ENSO activity inferred from a marine core near Lima, abrupt deglaciation in southern Chile, and Heinrich Event 1. Moderate to large increases in precipitation also occurred at 11,770-9550 (Central Atacama Pluvial Event), 7330-6720, 3490-2320 and at 800 cal yr BP. Desiccation occurred at 14,180, 8910-8640, and 4865 cal yr BP. Compared to other midden sites in the region, early Holocene desiccation seems to have happened progressively earlier farther south. Emerging trends from the cumulative midden record in the central Atacama agree at millennial timescales with improved paleolake chronologies for the Bolivian Altiplano, implying common forcing through changes in equatorial Pacific sea-surface temperature gradients.

  11. A rare case of grass flow induced by the M8.4 Arequipa earthquake, June 2001, in the Altiplano of Northern Chile

    Science.gov (United States)

    Naranjo, José A.; Clavero, Jorge E.

    2005-09-01

    On June 23, 2001, an M8.4 earthquake that originated in southern Peru triggered the partial collapse of the Chislluma bofedal (water meadows) in the Altiplano (high-altitude plateau) of northern Chile. The seismic waves evidently produced the liquefaction of the bofedal and caused its partial collapse generating a flow. The flow deposit was mainly made of long-fiber grass and water, with minor amounts of clastic material. It traveled more than 14 km downstream at a peak velocity of 50 km/h. It destroyed the water meadows and killed more than 20 llamas. Slurry flows caused by meadow liquefaction are a previously unrecognized seismic-induced geological hazard for high-altitude plateau areas such as the Altiplano.

  12. 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.

  13. 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

  14. The Bolivian Orocline and its implications for the origin of the central Andes

    Science.gov (United States)

    Arriagada, C.

    2015-12-01

    The tectonic evolution of the Central Andes includes a complex combination of thrusting, wrenching and block rotation leading progressively to the curvature of the orogenic system of the South American continental margin at 18ºS (Bolivian Orocline). Tectonic deformation in the Bolivian Orocline cannot be realistically restored using information from balanced cross sections alone, as the deformation includes an important component of block rotation, associated to counterclockwise block rotation in southern Peru and clockwise rotation in northern Chile. Recent work shows that block rotations in the forearc are essentially pre-early Miocene, predating the onset of Neogene shortening in the Sub Andean zone. Most rotations in the forearc of northern Chile where acquired through a single tectonic event during the Paleogene-early Miocene which probably coincides with the Eocene orogen-wide Incaic event which affected large regions of the central Andes between ca. 50 and 40 Ma. Results from 2D restoration experiments support the hypothesis of the Paleogene formation of the Bolivian Orocline, as a consequence of differential shortening, concentrated in the Eastern Cordillera of Bolivia, southern Peru and northwestern Argentina. Within the southern central Andes four additional curvatures including striking changes in the pattern of rotations have been discovered. From north to south these are the Antofagasta-Calama Lineament, Vallenar, Maipo and Arauco oroclines. However, an important part of rotation needs to be balanced, in the forearc region, by two major conjugate oblique shear zones (Abancay Deflection and Antofagasta-Calama Lineament). These structural features are probably related to inherited lithospheric discontinuities associated with the accretion of basement terranes which could be responsible for producing and delimitating significant and abrupt changes in the magnitude of the Central Andean Rotation Pattern along the margin. While shortening and crustal

  15. "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...

  16. Andean evolution of the Aluminé fold and thrust belt, Northern Patagonian Andes (38°30‧-40°30‧S)

    Science.gov (United States)

    García Morabito, Ezequiel; Ramos, Víctor A.

    2012-10-01

    The Aluminé fold and thrust belt between 38°30' and 40°30'S is the result of two periods of progression of deformation toward the foreland. The chronology of deformation and its relationship with magmatism through time show spatially and temporally separated magmatic events closely linked to distinct deformational stages. Data presented here confirms a Late Cretaceous mountain-building phase that coexisted in space and time with an eastward arc-migration. During this stage, a belt of deformation expanded through the foreland where it produced the Southern Neuquen Precordillera. This eastern independent mountain grew separately from the main Andean axis through a combination of inversion of the old rift systems and interaction with a pre-Andean belt which acted as a foreland obstacle. On the basis of tectonostratigraphic controls we define the last Andean contractional phase between the Late Miocene and the Pliocene. This event induced the reactivation of both sectors of the fold and thrust belt with minor propagation toward the foreland, leading to the uplift of the Patagonian Andes and reshaping the Southern Neuquén Precordillera. Both intervals of shortening are separated by a period of localized extension that resulted in the development of the Collón Cura basin within this Andean segment. Here, large thicknesses of volcanosedimentary sequences accumulated contemporaneously with the extensional activity between the earliest Oligocene and the Early Miocene.

  17. 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...

  18. 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...

  19. 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

  20. 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

  1. 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...

  2. 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

  3. 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.

  4. 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

  5. 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

  6. Glacial areas, lakes areas, and snowlines from 1975-2012: Status of the Cordillera Vilcanota, including the Quelccaya Ice Cap, northern central Andes, Peru

    Science.gov (United States)

    Hanshaw, Maiana Natania

    Glaciers in the tropical Andes of southern Peru have received limited attention compared to glaciers in other regions (both near and far), yet remain of vital importance to agriculture, fresh water, and hydropower supplies of downstream communities. Little is known about recent glacial-area changes and how the glaciers in this region respond to climate changes, and, ultimately, how these changes will affect lake and water supplies. To remedy this, we have used 144 multi-spectral satellite images spanning almost four decades, from 1975-2012, to obtain glacial and lake-area outlines for the understudied Cordillera Vilcanota region, including the Quelccaya Ice Cap. In a second step, we have estimated the snowline altitude of the Quelccaya Ice Cap using spectral unmixing methods. We have made the following four key observations: First, since 1988 glacial areas throughout the Cordillera Vilcanota have been declining at a rate of 5.46 +/- 1.70 km2/yr (22-year average, 1988-2010, with 95 % confidence interval). The Quelccaya Ica Cap, specifically, has been declining at a rate of 0.67 +/- 0.18 km2/yr since 1980 (31-year average, 1980-2011, also with 95 % confidence interval); Second, decline rates for individual glacierized regions have been accelerating during the past decade (2000-2011) as compared to the preceding decade (1990-2000); Third, the snowline of the Quelccaya Ice Cap is retreating to higher elevations as glacial areas decrease, by a total of almost 300 m between its lowest recorded elevation in 1989 and its highest in 1998; and fourth, as glacial regions have decreased, 61 % of lakes connected to glacial watersheds have shown a roughly synchronous increase in lake area, while 84 % of lakes not connected to glacial watersheds have remained stable or have declined in area. Our new and detailed data on glacial and lake areas over 37 years provide an important spatiotemporal assessment of climate variability in this area. These data can be integrated into further

  7. Glacial areas, lake areas, and snow lines from 1975 to 2012: status of the Cordillera Vilcanota, including the Quelccaya Ice Cap, northern central Andes, Peru

    Science.gov (United States)

    Hanshaw, M. N.; Bookhagen, B.

    2014-03-01

    Glaciers in the tropical Andes of southern Peru have received limited attention compared to glaciers in other regions (both near and far), yet remain of vital importance to agriculture, fresh water, and hydropower supplies of downstream communities. Little is known about recent glacial-area changes and how the glaciers in this region respond to climate changes, and, ultimately, how these changes will affect lake and water supplies. To remedy this, we have used 158 multi-spectral satellite images spanning almost 4 decades, from 1975 to 2012, to obtain glacial- and lake-area outlines for the understudied Cordillera Vilcanota region, including the Quelccaya Ice Cap. Additionally, we have estimated the snow-line altitude of the Quelccaya Ice Cap using spectral unmixing methods. We have made the following four key observations: first, since 1988 glacial areas throughout the Cordillera Vilcanota (1988 glacial area: 361 km2) have been declining at a rate of 3.99 ± 1.15 km2 yr-1 (22 year average, 1988-2010, with 95% confidence interval (CI), n = 8 images). Since 1980, the Quelccaya Ice Cap (1980 glacial area: 63.1 km2) has been declining at a rate of 0.57 ± 0.10 km2 yr-1 (30 year average, 1980-2010, with 95% CI, n = 14). Second, decline rates for individual glacierized regions have been accelerating during the past decade (2000-2010) as compared to the preceding decade (1988-1999) with an average increase from 37.5 to 42.3 × 10-3 km2 yr-1 km-2 (13%). Third, glaciers with lower median elevations are declining at higher rates than those with higher median elevations. Specifically, glaciers with median elevations around 5200 m a.s.l. are retreating to higher elevations at a rate of ~1 m yr-1 faster than glaciers with median elevations around 5400 m a.s.l. Fourth, as glacial regions have decreased, 77% of lakes connected to glacial watersheds have either remained stable or shown a roughly synchronous increase in lake area, while 42% of lakes not connected to glacial

  8. 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)

  9. Paleoseismology of the Mejillones Fault, northern Chile: Insights from cosmogenic 10Be and optically stimulated luminescence determinations

    Science.gov (United States)

    CortéS A., J.; GonzáLez L., Gabriel; Binnie, S. A.; Robinson, R.; Freeman, S. P. H. T.; Vargas E., G.

    2012-04-01

    We have undertaken the first paleoseismological study on an upper plate fault in Chile. The selected structure was the Mejillones Fault, which is marked by a conspicuous fault-scarp. Using cosmogenic 10Be and OSL dating and detailed sedimentary logging of trenches, we have constrained the abandonment of two alluvial surfaces by fault activity at ca. 35 ka and ca.14 ka. Based on stratigraphic observation we characterized the fault evolution in four intervals over the last ca. 35 ka. During the first three intervals the fault had a steady slip rate of 0.61 ± 0.26 m/ka. The fourth interval is delineated by the last vertical fault slip and the accumulation of un-deformed hillslope deposits after ca. 3.3 ka and has a slip rate of 0.22 ± 0.06 m/ka. The younger surface abandonment was caused by two Mw ˜ 7 paleoearthquakes with a recurrence interval of 5.0 ± 3.5 ka. The third interval is characterized by the interaction of hillslope deposits and aseismic slip and/or centimeter scale seismic slip events. At ca. 3.5 ka, a last large (Mw ˜ 6.6) earthquake took place. The recurrence intervals of large (Mw > 8.5) subduction earthquakes do not appear to be the same as the recurrence intervals of the Mw ˜ 7 events on the upper plate Mejillones Fault.

  10. 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.

  11. 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.

  12. 3D seismic velocity structure in the rupture area of the 2014 M8.2 Iquique earthquake in Northern Chile

    Science.gov (United States)

    Woollam, Jack; Fuenzallida, Amaya; Garth, Tom; Rietbrock, Andreas; Ruiz, Sergio; Tavera, Hernando

    2016-04-01

    Seismic velocity tomography is one of the key tools in Earth sciences to image the physical properties of the subsurface. In recent years significant advances have been made to image the Chilean subductions zone, especially in the area of the 2010 M8.8 Maule earthquake (e.g. Hicks et al., 2014), providing much needed physical constraints for earthquakes source inversions and rupture models. In 2014 the M8.2 Iquique earthquake struck the northern part of the Chilean subduction zone in close proximity to the Peruvian boarder. The pre- and aftershock sequence of this major earthquake was recorded by a densified seismological network in Northern Chile and Southern Peru, which provides an excellent data set to study in depth the 3D velocity structure along the subduction megathrust. Based on an automatic event catalogue of nearly 10,000 events spanning the time period March to May 2014 we selected approximately 450 events for a staggered 3D inversion approach. Events are selected to guarantee an even ray coverage through the inversion volume. We only select events with a minimum GAP of 200 to improve depth estimates and therefore increase resolution in the marine forearc. Additionally, we investigate secondary arrivals between the P- and S-wave arrival to improve depth location. Up to now we have processed about 450 events, from which about 150 with at least 30 P- and S-wave observations have been selected for the subsequent 3D tomography. Overall the data quality is very high, which allows arrival time estimates better than 0.05s on average. We will show results from the 1D, 2D, and preliminary 3D inversions and discuss the results together with the obtained seismicity distribution.

  13. 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

  14. Fires in Chile

    Science.gov (United States)

    2002-01-01

    On February 5, 2002, the dense smoke from numerous forest fires stretched out over the Pacific Ocean about 400 miles south of Santiago, Chile. This true-color Moderate-resolution Imaging Spectroradiometer (MODIS) image shows the fires, which are located near the city of Temuco. The fires are indicated with red dots (boxes in the high-resolution imagery). The fires were burning near several national parks and nature reserves in an area of the Chilean Andes where tourism is very popular. Southeast of the fires, the vegetation along the banks of the Rio Negro in Argentina stands out in dark green. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  15. Variación ambiental y patrones di etarios del erizo negro Tetrapygus niger en costas intermareales rocosas del norte de Chile Environmental variation and dietary patterns of the black urchin Tetrapygus niger in rocky intertidal shores of northern Chile

    Directory of Open Access Journals (Sweden)

    ARTURO H NAVARRETE

    2008-09-01

    temperatura superficial del mar, y fue significativamente menor en todo el período de El Niño 2004-2005. Nuestros datos sugieren que T. niger es un generalista polífago cuyos patrones de consumo son fuertemente modulados por la fluctuación t��rmica ambiental. Además, hipotetizamos que T. niger puede usar estrategias oportunistas y selectivas sobre distintos recursos, y que su conectividad y posición trófica serían más complejas que las de un simple consumidor primario.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 black urchin Tetrapygus niger (Molina in the coast of Chile. In this context, we analyzed the variation in diet richness and composition of the black urchin in four rocky intertidal communities over a 1,000 km stretch of coast in northern Chile, sampled seasonally between the austral winter of 2004 and spring of 2005. The 2004-2005 El Niño event took place during the study, and we incorporated its potential effects to this evaluation. For each community and season, we measured the abundance of species present in 45 quadrants (0.25 m² distributed between five permanent blocks, collecting about 10 individuals of T. niger to measure their body size (dry biomass and maximum diameter and to determine the number, identity and occurrence frequency of dietary items in their gastric tract. We collected a total of 251 urchin individuals, which consumed 89 items of algae (64 % and invertebrates (36 %; including other herbivores. A significant inverse relationship between the number of ingested animal items and body size suggests that T. niger changes its diet throughout the ontogeny. Dietary niche breadth was high but tended to decrease toward lower latitudes. The spectrum and occurrence frequency of dietary items were not significantly different among communities, despite their marked differences in upwelling

  16. New species of high elevation cloud forest butterflies of the genus Pedaliodes Butler from the northern Colombian Andes (Lepidoptera, Nymphalidae, Satyrinae).

    Science.gov (United States)

    Pyrcz, Tomasz W; Prieto, Carlos; Viloria, Angel L; Andrade, Gonzalo

    2013-01-01

    Four new species of Pedaliodes Butler (i.e., P. adrianae, n. sp., P. haydoni, n. sp., P. philinae, n. sp. and P. rodriguezi, n. sp.) are described from the high elevation cloud forests in the Frontino massif in the Colombian Western Cordillera and the northern part of the Central and Eastern Cordilleras. The affinities of these new species with other congeners are discussed. The total number of described species of Colombian Pronophilina is increased to 208, with a particularly high total number of species (88) and proportion of endemic species (26%) in the Western Cordillera.

  17. 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.

  18. 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

  19. 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

  20. Neotectonics In The Central Depression (atacama Desert, 25-26°s, Northern Chile) and Its Implications For Recent Sedimentary Fluxes and Regional Deformation

    Science.gov (United States)

    Audin, L.; Hérail, G.; Riquelme, R.; Darrozes, J.; Martinod, J.; Font, E.

    In the northern Chilean Andes, the Pampas Exploradora and Carizo are part of a NS- trending basin (known as the Central Depression) that separates the Coastal Range from the Precodillera. The Exploradora and Carizo region has undergone an extremely arid climate at least since the Middle Miocene time (~15 Ma ago). The limited extent of erosion, due to exceptional aridity, has greatly contributed to the preservation of the landform. In such environment the landforms can be very well used to analyse the tectonic evolution. A basin infilling occurred during the Cenozoic (Atacama Gravels) with the deposition of large volumes of coarse gravels coming from the Precordillera. The aggradation and filling of the paleo-drainage system by the Atacama Gravels of fluviatil origin mark an important erosive unconformity. Moreover, this uniform preserved surface has undergone low magnitude deformation during the deposition period. But we have evidenced a late and post Atacama Gravel tectonic episode. On the western side of the Precordillera a number of normal faults that cross a dense network of very well preserved channels and its alluvial fans. This tectonic deformation is not large in magnitude, about 2m of vertical offset, but clearly appear in the landscape suggesting that the landforms and deformation in the western part of the basin may be quite young. The easterly dipping normal fault set does not correspond with a regional dip toward the west and thus does not satisfy an hypothesis of gravitationnal reajustment or collapse. On the contrary, west of the normal fault set, some ongoing compressional forces are revealed by a large scale folding of the Central basin. These tectonic features led to some minor topographic variations that produced on the top of the basin surface local sedimentary traps, regressive erosion, catchments and extrado grabens that controlled the sediment facies and distribution pattern. Recent coarse-grained alluvial fans were deposited and stopped by

  1. 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

  2. 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

  3. 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

  4. Assessment of trace metals and porphyrins in excreta of Humboldt penguins (Spheniscus humboldti) in different locations of the northern coast of Chile.

    Science.gov (United States)

    Celis, José E; Espejo, Winfred; González-Acuña, Daniel; Jara, Solange; Barra, Ricardo

    2014-03-01

    To add data on trace metal contamination of Humboldt penguins in the South Pacific, levels of trace metals (As, Hg, Pb, Cu, Zn, and Cd) and porphyrins (copro-, uro-, and proto-) in excreta of Humboldt penguins that inhabit some important nesting sites on the northern coast of Chile were determined. Fresh excreta were collected on Pan de Azúcar Island, Chañaral Island, and Cachagua Island, from December 2011 to January 2012. Concentration of metals was determined by flame atomic absorption spectrophotometry, whereas porphyrins levels were measured by fluorimetric analysis. Concentrations (dry weight) of Cu (199.67 μg g(-1)), As (7.85 μg g(-1)), and Pb (12.78 μg g(-1)) were higher (p ≤ 0.05) in Cachagua Island. Colonies from Pan de Azúcar Island showed the highest levels of Hg (0.76 μg g(-1)), Cd (47.70 μg g(-1)), and Zn (487.10 μg g(-1)). Samples from Cachagua Island showed the highest (p ≤ 0.05) levels of copro- (2.16 nmol g(-1)), uro- (2.20 nmol g(-1)), and protoporphyrins (2.23 nmol g(-1)). There was a positive correlation between the metals As, Pb, and Cu with uro-, copro-, and protoporphyrins. The results indicated that penguin colonies from Cachagua Island are more exposed to metal contamination than penguin colonies from Pan de Azúcar and Chañaral Islands, thus being more likely to develop certain diseases caused by contamination with metals. Considering biomagnification, the metals detected in the excreta of Humboldt penguins can be a source of contamination from marine environments to terrestrial ecosystems, which could also affect other living organisms.

  5. 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.

  6. U-Pb Geochronology, Geochemistry and Kinematic Analyses of Subduction-Related Late Triassic Basins in Northern Chile (24.5º-26ºS).

    Science.gov (United States)

    Espinoza, M. E.

    2015-12-01

    In northern Chile (24.5°-26°S) two Pre-Andean depocenters crop out: the Cifuncho basin in the Coastal Cordillera and the Profeta basin in the Precordillera. These basins have been classically interpreted as a continental rifting unrelated to subduction during the period prior to the Andean orogenic cycle. However, recent petrographic and geochemical data suggest the development of these basins in an active subduction system. In order to test this hypothesis and to establish the geologic evolution of the basins and the strain field during the rifting process, we present preliminary U-Pb geochronological and geochemical data together with structural analyses of synrift structures. The geochronological data along the Cifuncho and Profeta basins, show a main continental sedimentary deposition during the Norian to Raethian. Volcanosedimentary rocks show a main detrital supply of Early Permian age (~297-283 Ma). This input can be associated with the volcanic La Tabla Formation and/or the exhumation of Permian granitoids. A minor supply close to ~478 Ma is related to a source from the Lower Ordovician arc (~480 Ma), suggesting the tectonic exhumation of this source to the east of the Profeta basin during the Late Triassic. On the other hand, structural analysis was carried in third and four order extensional faults (<10 m of slip) along the Profeta basin. Most of the faults show a clear synrift character with the development of fault controlled growing strata. The kinematic analyses evidence a variability in the orientation of the maximum strain axes from a main northwest to a subordinate northeast direction of extension. Thus, the intimate relation between the continental sedimentary deposition and a proximal volcanism of intermediate composition and calk-alkaline affinity, suggests the development of these basins in a supra-subduction setting during the Late Triassic. Structural data probably reflect local variation in the strain field across the basins.

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

    Directory of Open Access Journals (Sweden)

    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.

  8. 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.

  9. Stress fields during the evolution of large-scale strike-slip systems and tectonic slivers, Atacama Fault Zone, northern Chile

    Science.gov (United States)

    Veloso, E. E.; Gomila, R.

    2009-12-01

    Tectonic evolution of crustal slivers generated during oblique subduction involves a series of translations and rotations. Slivers are defined by large-scale strike-slip faults, whereas internal blocks are by the faulting pattern related to the fault system. Translations and rotations are then likely to accommodate the internal deformation caused by external forces. The Atacama Fault System (AFS), a crustal-scale strike-slip fault in northern Chile, can be divided into three concave, oceanward segments, that show sinestral (Mesozoic) and normal (Cenozoic) displacements. Clockwise rotations of ca. 50° have been suggested for the AFS, mostly for the northernmost segment. The Paposo segment defines a sliver of 160 km long and 25 km wide. In the northern part, it exhibits intense internal faulting, duplexes, single- and multiple-core faults. To determine the stress field responsible for the development and evolution of the sliver, we measured 162 brittle fault planes on which we determined the sense and direction of maximum shear. Fault planes show a main NW-SE trend and subvertical dip-angles (Fig. 1). Brittle kinematic indicators indicate subhorizontal (sinestral) and subvertical (normal) movements. Fault-slip data was processed with the multiple inverse method. Input parameters were k=5 (grouping), e=9 (enhance) and d=1 (dispersion). Calculations show that σ1 axes are distributed on a NW-SE trending great-circle whereas σ3 axes are clustered near the horizontal in NE and SW orientations. Stress ratios average 0.55±0.20. In the horizontal, σ1 axes cover an arc of about 30° and σ3 axes cover about 60° (Fig. 1), suggesting a strike-slip stress field. On the contrary, the subvertical cluster of σ1 axes suggests a normal stress field. These analyses indicate that the Paposo Sliver developed during a period of NW-SE compression and NE-SW tension. The wide distribution of the tensile axes may denote rotation of the internal blocks to accommodate the deformation or

  10. 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

  11. 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

  12. 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

  13. 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

  14. Common catabolic enzyme patterns in a microplankton community of the Humboldt Current System off northern and central-south Chile: Malate dehydrogenase activity as an index of water-column metabolism in an oxygen minimum zone

    Science.gov (United States)

    González, R. R.; Quiñones, R. A.

    2009-07-01

    An extensive subsurface oxygen minimum zone off northern and central-south Chile, associated with the Peru-Chile undercurrent, has important effects on the metabolism of the organisms inhabiting therein. Planktonic species deal with the hypoxic and anoxic environments by relying on biochemical as well as physiological processes related to their anaerobic metabolisms. Here we characterize, for the first time, the potential enzymatic activities involved in the aerobic and anaerobic energy production pathways of microplanktonic organisms (catabolic pathways in the oxygen minimum zone. Malate dehydrogenase had the highest oxidizing activity of nicotinamide adenine dinucleotide (reduced form) in the batch of catabolic enzymatic activities assayed, including potential pyruvate oxidoreductases activity, the electron transport system, and dissimilatory nitrate reductase. Malate dehydrogenase correlated significantly with almost all the enzymes analyzed within and above the oxygen minimum zone, and also with the oxygen concentration and microplankton biomass in the water column of the Humboldt Current System, especially in the oxygen minimum zone off Iquique. These results suggest a possible specific pattern for the catabolic activity of the microplanktonic realm associated with the oxygen minimum zone spread along the Humboldt Current System off Chile. We hypothesize that malate dehydrogenase activity could be an appropriate indicator of microplankton catabolism in the oxygen minimum zone and adjacent areas.

  15. 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

  16. 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.

  17. Mesozoic fault systems, deformation and fault block rotation in the Andean forearc: a crustal scale strike-slip duplex in the Coastal Cordillera of northern Chile

    Science.gov (United States)

    Taylor, G. K.; Grocott, J.; Pope, A.; Randall, D. E.

    1998-12-01

    In this paper we discuss the evolution and tectonic significance of the Mesozoic trench-parallel fault systems which affected the Coastal Cordillera and their relation to magmatism and crustal rotation. The oldest, extensional, fault system separates basement from rift-related Late Triassic and younger sedimentary units. This system [I] subsequently developed into a wider extensional fault system which acted as the locus of magma ascent and emplacement of the Coastal Batholith during much of the Jurassic to earliest Cretaceous period. This extensional fault system defined the forearc sliver during this period and was the consequence of a retreating subduction boundary. During the Early Cretaceous (c. 132-125 Ma) the kinematics of this fault system changed to transtension [II] and accommodated a major component of left-lateral strike-slip motion, the principal fault being the Atacama Fault Zone along which plutons continued to be emplaced. The final phase of pluton emplacement within the Coastal Cordillera appears to be c. 106 Ma, after which this magmatic arc and fault system was abandoned. An Late Cretaceous arc and fault system [III] developed some 20 Ma later and located some 50 km to the east in what is now the Central Valley of northern Chile. This paper seeks to show that the Coastal Cordillera was deformed as a whole by this Late Cretaceous fault system [III] which formed a crustal-scale left-lateral transpressional duplex. During this deformation the thermally weakened crust was dissected into a series of large-scale blocks bounded by NW-trending left-lateral strike-slip faults which merge into a NNE-SSW fault zone which forms the eastern boundary to the duplex. We term this eastern boundary zone the Central Valley Fault Zone (CVFZ) and this together with the NW-trending faults defines the duplex system which we refer to as a whole as the Coastal Cordillera Fault System (CCFS) [III]. We have traced the CCFS duplex between 25°S and 29°S and suspect that it

  18. Fault zone development and strain partitioning in an extensional strike-slip duplex: A case study from the Mesozoic Atacama fault system, Northern Chile

    Science.gov (United States)

    Cembrano, J.; González, G.; Arancibia, G.; Ahumada, I.; Olivares, V.; Herrera, V.

    2005-05-01

    Upper crustal strike-slip duplexes provide an excellent opportunity to address the fundamental question of fault zone development and strain partitioning in an evolving system. Detailed field mapping of the Mesozoic Atacama fault system in the Coastal Cordillera of Northern Chile documents the progressive development of second- and third-order faults forming a duplex at a dilational jog between two overstepping master faults: the sinistral strike-slip, NNW-striking, Jorgillo and Bolfin faults. These are constituted by a meter-wide core of foliated S-C ultracataclasite and cataclasite, flanked by a damage zone of protocataclasite, splay faults and veins. Lateral separation of markers along master faults is on the order of a few kilometers. Second-order, NW-striking, oblique-slip subsidiary fault zones do not show foliated ultracataclasite; lateral sinistral separations are in the range of ˜ 10 to 200 m with a relatively minor normal dip-slip component. In turn, third-order, east-west striking normal faults exhibit centimetric displacement. Oblique-slip (sinistral-normal) fault zones located at the southern termination of the Bolfin fault form a well-developed imbricate fan structure. They exhibit a relatively simple architecture of extensional and extensional-shear fractures bound by low displacement shear fractures. Kinematic analysis of fault slip data from mesoscopic faults within the duplex area, document that the NW-striking and the EW-striking faults accommodate transtension and extension, respectively. Examination of master and subsidiary faults of the duplex indicates a strong correlation between total displacement and internal fault structure. Faults started from arrays of en echelon extensional/extensional-shear fractures that then coalesced into throughgoing strike-slip faults. Further displacement leads to the formation of discrete bands of cataclasite and ultracataclasite that take up a significant part of the total displacement. We interpret that the

  19. 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

  20. 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

  1. SHRIMP U-Pb dating of the Antucoya porphyry copper deposit: new evidence for an Early Cretaceous porphyry-related metallogenic epoch in the Coastal Cordillera of northern Chile

    Science.gov (United States)

    Maksaev, Victor; Munizaga, Francisco; Fanning, Mark; Palacios, Carlos; Tapia, José

    2006-10-01

    The Antucoya porphyry copper deposit (300 Mt at 0.45% total Cu) is one of the largest deposits of a poorly known Early Cretaceous porphyry belt in the Coastal Cordillera of northern Chile. It is related to a succession of granodioritic and tonalitic porphyritic stocks and dikes that were emplaced within Jurassic andesitic rocks of the La Negra Formation immediately west of the N-S trending sinistral strike-slip Atacama Fault Zone. New zircon SHRIMP U-Pb data indicate that the porphyries of Antucoya crystallized within the time span from 142.7 ± 1.6 to 140.6 ± 1.5 Ma (±2 σ), and late, unmineralized, NW-SE trending dacite dikes with potassic alteration and internal deformation crystallized at 141.9 ± 1.4 Ma. The Antucoya porphyry copper system appears to be formed after a change of stress conditions along the magmatic arc from extensional in the Late Jurassic to transpressive during the Early Cretaceous and provides support for an Early Cretaceous metallogenic episode of porphyry-type mineralization along the Coastal Cordillera of northern Chile.

  2. 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.

  3. Chile exploits LNG

    Energy Technology Data Exchange (ETDEWEB)

    1980-03-01

    Simultaneously with its exploitation of offshore hydrocarbon reservoirs Chile is developing the production and selling of LNG. Chile produces a large quantity of associated gas from its reservoirs at Megallanes and processes it at the Manantiales, Cullen and Posesion plants recovering propane, butane and natural gas liguids. The stripped gas is reinjected for pressure maintenance operations. With the completion of the LNG program full use of the gas will be achieved. It will totally meet the needs of combustible liquids for the central and northern parts of the country, a volume of 2200 million cu m/yr. For its treatment natural gas is sent through gas pipelines to the LNG plant at Cabo Negro. By means of a cooling process, the gas is cooled to -160 C where it becomes a liquid and its volume is reduced by a factor of 600. It is then stored in tanks at atmospheric pressure.

  4. 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...

  5. 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

  6. 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...

  7. 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

    The study of past climate variability from ice core investigations has been largely developed both in polar areas over the past decades and, more recently, in tropical regions, specifically along the South American Andes between 0° and 20°S. However a large gap still remains at mid-latitudes in t...... of these two very distinct source areas changing at the interannual timescale. Thus this site should offer a wealth of information regarding (South) Pacific, Argentinian NE-E areas and Antarctic climate variability. Udgivelsesdato: 2008.08.28......The study of past climate variability from ice core investigations has been largely developed both in polar areas over the past decades and, more recently, in tropical regions, specifically along the South American Andes between 0° and 20°S. However a large gap still remains at mid...... 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...

  8. 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

  9. 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...

  10. Is a vertebrate a better host for a parasite than an invertebrate host? Fecundity of Proctoeces cf lintoni (Digenea: Fellodistomidae), a parasite of fish and gastropods in northern Chile.

    Science.gov (United States)

    Oliva, Marcelo Enrique; Alvarez, Carlos

    2011-12-01

    The fecundity, the relationship between fecundity and worm size, as well as abundance of the adult worm Proctoeces cf. lintoni (Digenea: Fellodistomidae) in four gastropod hosts (keyhole limpets of the genus Fissurella) and one vertebrate host, the clingfish Sicyases sanguineus from northern Chile, were compared. Worms obtained from Fissurella latimarginata were smaller than those from Fissurella maxima, Fissurella limbata, and S. sanguineus. The mean fecundity of parasites from Fissurella crassa was significantly lower than those from F. limbata, F. maxima and S. sanguineus. For all invertebrate hosts, there were significant, positive relationships between worm size and fecundity, and the slopes of the regression did not differ significantly for the invertebrate hosts. Parasites of the keyhole limpet F. limbata and the clingfish showed the highest intensity, prevalence, and mean fecundity, and these species must be considered to be the hosts in which P. cf lintoni shows the best fitness.

  11. 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

  12. 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

    Directory of Open Access Journals (Sweden)

    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.

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  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

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    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. Variabilidad y estructura genética en dos poblaciones de Vicugna vicugna (Camelidae del norte de Chile Genetic variability and structure in two populations of Vicugna vicugna (Camelidae from northern Chile

    Directory of Open Access Journals (Sweden)

    M. CECILIA NORAMBUENA

    2003-03-01

    Full Text Available RESUMEN Se estudiaron dos poblaciones de Vicugna vicugna pertenecientes a la Primera y Segunda regiones del país, en base a la determinación electroforética de 28 loci presumtivos. Las diferencias fenotípicas existentes entre las vicuñas de estas poblaciones hace necesario este trabajo con el fin de re-estudiar su posición taxonómica y obtener antecedentes de variabilidad genética y estructura poblacional que podrían resultar útiles en su manejo de conservación. En la población de vicuñas de la Primera Región se detectó un polimorfismo de 17,8 % y un nivel de heterocigosidad de 0,078. En aquellas de la Segunda Región, el polimorfismo y la heterocigosidad se estimaron en 14,3 % y 0,045, respectivamente. Ambos parámetros revelan un alto grado de variabilidad genética poblacional. Se encontró un nivel de subestructuración démica alto (F ST = 0,344 y un grado de diferenciación génico y genotípico significativo entre las poblaciones. Se infiere que la deriva genética y el sistema social poligámico tendrían un rol importante como promotores de las diferencias genéticas observadas. El valor de distancia génica (D = 0,097 no confirmó el estatus subespecífico atribuido en base a sus diferencias morfológicas.Two populations of Vicugna vicugna from regions First and Second of Chile were studied on the basis of the electrophoretic determination of 28 presumptive loci. Due to the phenotypic differences between the populations mentioned above, this kind of study is required to determine some parameters like taxonomic status, genetic variability and population structure in order to help in conservation management of the specie. The percentage of polymorphism and the level of heterozigosity of vicuñas from the First region were 17.8 % and 0.078, respectively. The corresponding figures of vicuñas from the Second were 14.3 % and 0.045, respectively. These two parameters show that the two populations have a high degree of genetic

  2. 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.

  3. 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

    Science.gov (United States)

    Diaz, Oscar Pablo; Arcos, Rafael; Tapia, Yasna; Pastene, Rubén; Velez, Dínoraz; Devesa, Vicenta; Montoro, Rosa; Aguilera, Valeska; Becerra, Miriam

    2015-01-01

    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. PMID:26006131

  4. 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

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    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

  5. 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 environments; an upper crustal environment identical to that recorded in the Purico ignimbrite, and a second deeper, ∼15-20 km depth, higher temperature (∼922-1001

  6. 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...

  7. Two New Species of Black Flies (Diptera: Simuliidae) from the High Andes of Colombia.

    Science.gov (United States)

    Mantilla, Juan S; Moncada, Ligia I; Matta, Nubia E; Adler, Peter H

    2013-01-01

    The females, males, pupae, and larvae of two new species of Simulium are described and illustrated from a small stream 3950 m above sea level in the Lake Otún area of the Colombian Andes Mountains. Simulium (Pternaspatha) quimbayium n. sp. represents a 630-km northeastern extension of the distributional range of previously known members of the subgenus Pternaspatha, and Simulium (Psilopelmia) machetorum n. sp. represents the highest altitude recorded for a species of the subgenus Psilopelmia. These species illustrate the unique simuliid biodiversity in the páramo ecosystem of the high northern Andes.

  8. 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

  9. Hydrochemical processes controlling arsenic and heavy metal contamination in the Elqui river system (Chile).

    Science.gov (United States)

    Dittmar, Thorsten

    2004-06-01

    Severe arsenic poisoning from drinking water has been documented in Northern Chile. However, the Elqui River, which provides water for approximately 200,000 people in this region, is poorly studied and no data on contaminants have been published to date. In this study, trace elements and the main aqueous constituents were monitored for approximately 2 years in the entire river system. Aqueous species of trace elements were determined via thermodynamic equilibrium calculations, and two operationally-defined suspended fractions were analyzed. Chalco- and arsenopyrite deposits in the upper Andes, in conjunction with mining and geothermal activity, were identified as exclusive point sources of heavy metals and arsenic. The annual input to the river system was approximately (t year(-1)): Fe 600, Mn 110, Cu 130, Zn 35 and As 2.0. The confluence with pH-buffered waters in the upper river system caused collapse of iron hydroxide colloids and coprecipitation of all heavy metals, e.g. dissolved copper concentrations decreased from approximately 100 to approximately 0.2 micromol l(-1), which is still of ecotoxic concern. The heavy metal enriched suspended solids settled only in the lower Elqui River. Arsenate did not adsorb to suspended solids and behaved strictly conservatively, exceeding the WHO guideline value for drinking water (0.13 micromol l(-1)) in the entire river system. Decontamination may be accomplished with reasonable efforts upstream in direct vicinity to the sources via coprecipitation, settling and appropriate pH adjustment for arsenate adsorption. PMID:15144789

  10. 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

  11. 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

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

    OpenAIRE

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

    2011-01-01

    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 M(w) = 7.7 Nazca, the 2001 M(w) = 8.4 Arequipa, the 2007 M(w) = 8.0 Pisco and the M(w) = 7....

  13. 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

  14. 87Sr/86Sr in Gypsic Relict Soils and Paleosols of Hyperarid Settings as a Paleoaltitude Proxy: Results for Northern Chile (19.5-21.7°S)

    Science.gov (United States)

    Jordan, T. E.; Cosentino, N. J.

    2014-12-01

    We have developed a new altimeter proxy based on the 87Sr/86Sr ratio of surficial accumulations of salts in hyperarid settings. Under hyperarid conditions like in the Andean forearc in northern Chile at altitudes below ~3000 m.a.s.l., gypsum and other soluble salts form saline soils. The altimeter is based on the first-order topographic control on the extent of inland incursion of fog-transported marine aerosols derived from the Pacific Ocean. Once this fog is evaporated it deposits calcium sulfates with a marine 87Sr/86Sr signal. At positions in the landscape not reached by marine aerosols, calcium sulfates have no marine source, except by eolian reworking, and have a lower 87Sr/86Sr. 87Sr/86Sr values for Holocene accumulations of salts show a bimodal distribution: high values between 225-1075 m.a.s.l. (0.70807 ± 0.00004) and low values below and above those altitude thresholds (0.70746 ± 0.00010). We sampled dated gypsic relict soils and Gypsisols to study post-5 Ma surface height evolution using this method, after correcting for changes in the altitudinal structure of the paleo-fog zone with time. Locations spanning ~250 km strike-parallel distance within the forearc and at elevations between 450-1650 m.a.s.l. display moderate amounts of altitudinal change during the Pliocene, Pleistocene and Quaternary. Site results include two in the northern zone (19.5ºS and 19.65ºS) that experienced maximum net surface uplifts of ~350 m and ~600 m since 2.5 ± 0.5 Ma and ~2.6 Ma, respectively. Locations at ~21.4°S display an estimated minimum net decline in altitude of ~250 m since 3.4 ± 1.1 Ma and ~200 m since 1.1 ± 0.4 Ma. These constraints will shed light on the geodynamic processes responsible for surface elevation change, by acting as boundary conditions to numerical models of the Andean forearc.

  15. 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...

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. Lake Andes NWR Water Use Report- 1958

    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 1958. The report highlights the weather, water, habitat, and wildlife conditions for the year of...

  9. The nature and origin of off-fault damage surrounding strike-slip fault zones with a wide range of displacements: A field study from the Atacama fault system, northern Chile

    Science.gov (United States)

    Mitchell, T. M.; Faulkner, D. R.

    2009-08-01

    Damage surrounding the core of faults is represented by deformation on a range of scales from microfracturing of the rock matrix to macroscopic fracture networks. The spatial distribution and geometric characterization of damage at various scales can help to predict fault growth processes, subsequent mechanics, bulk hydraulic and seismological properties of a fault zone. Within the excellently exposed Atacama fault system, northern Chile, micro- and macroscale fracture densities and orientation surrounding strike-slip faults with well-constrained displacements ranging over nearly 5 orders of magnitude (˜0.12 m-5000 m) have been analyzed. Faults have been studied that cut granodiorite and have been passively exhumed from 6 to 10 km depth. This allows direct comparison of the damage surrounding faults of different displacements. The faults consist of a fault core and associated damage zone. Macrofractures in the damage zone are predominantly shear fractures orientated at high angles to the faults studied. They have a reasonably well-defined exponential decrease with distance from the fault core. Microfractures are a combination of open, healed, partially healed and fluid inclusion planes (FIPs). FIPs are the earliest set of fractures and show an exponential decrease in fracture density with perpendicular distance from the fault core. Later microfractures do not show a clear relationship of microfracture density with perpendicular distance from the fault core. Damage zone widths defined by the density of FIPs scale with fault displacement but appear to reach a maximum at a few km displacement. One fault, where damage was characterized on both sides of the fault core shows no damage asymmetry. All faults appear to have a critical microfracture density at the fault core/damage zone boundary that is independent of displacement. An empirical relationship for microfracture density distribution with displacement is presented. Preferred FIP orientations have a high angle to

  10. 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.

  11. Global water watch in the Andes

    OpenAIRE

    S. Ruiz-Córdova; B. Duncan

    2001-01-01

    An "offspring" of SANREM Philippines experience, the Water Resources Management and Environmental Education activity in the Andes is approaching problems of water through community-based, participatory research. Forty-three citizens in Ecuador and eleven in Peru have become certified water quality monitors. Under sponsorship of UNORCAC, SANREM's partner in the Andes, a significant portion of water quality data obtained is the result of their efforts. Since July 1999 a time series of 2,800 bac...

  12. 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

  13. 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

  14. U-Pb, Re-Os, and 40Ar/39Ar geochronology of the Nambija Au-skarn and Pangui porphyry Cu deposits, Ecuador: implications for the Jurassic metallogenic belt of the Northern Andes

    Science.gov (United States)

    Chiaradia, Massimo; Vallance, Jean; Fontboté, Lluis; Stein, Holly; Schaltegger, Urs; Coder, Joshua; Richards, Jeremy; Villeneuve, Mike; Gendall, Ian

    2009-05-01

    New U-Pb, Re-Os, and 40Ar/39Ar dates are presented for magmatic and hydrothermal mineral phases in skarn- and porphyry-related ores from the Nambija and Pangui districts of the Subandean zone, southeastern Ecuador. Nambija has been one of the main gold-producing centers of Ecuador since the 1980s due to exceptionally high-grade ores (average 15 g/t, but frequently up to 300 g/t Au). Pangui is a recently discovered porphyry Cu-Mo district. The geology of the Subandean zone in southeastern Ecuador is dominated by the I-type, subduction-related, Jurassic Zamora batholith, which intrudes Triassic volcanosedimentary rocks. The Zamora batholith is in turn cut by porphyritic stocks, which are commonly associated with skarn formation and/or porphyry-style mineralization. High precision U-Pb and Re-Os ages for porphyritic stocks (U-Pb, zircon), associated prograde skarn (U-Pb, hydrothermal titanite), and retrograde stage skarn (Re-Os, molybdenite from veins postdating gold deposition) of the Nambija district are all indistinguishable from each other within error (145 Ma) and indicate a Late Jurassic age for the gold mineralization. Previously, gold mineralization at Nambija was considered to be Early Tertiary based on K-Ar ages obtained on various hydrothermal minerals. The new Jurassic age for the Nambija district is slightly younger than the 40Ar/39Ar and Re-Os ages for magmatic-hydrothermal minerals from the Pangui district, which range between 157 and 152 Ma. Mineralization at Nambija and Pangui is associated with porphyritic stocks that represent the last known episodes of a long-lived Jurassic arc magmatism (˜190 to 145 Ma). A Jurassic age for mineralization at Nambija and Pangui suggests that the Northern Andean Jurassic metallogenic belt, which starts in Colombia at 3° N, extends down to 5° S in Ecuador. It also adds a new mineralization style (Au-skarn) to the metal endowment of this belt.

  15. 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.

  16. Foreland shortening and crustal balancing in the Andes at 30°S latitude

    Science.gov (United States)

    Allmendinger, R. W.; Figueroa, D.; Synder, D.; Beer, J.; Mpodozis, C.; Isaacks, B. L.

    1990-08-01

    Excellent surface exposures, known Benioff zone geometry, a dynamic morphology, and the availability of industry seismic reflection data all make the Andes at 30°S an excellent transect for investigating crustal-scale balanced sections. 150-170 km of horizontal shortening has occurred in three major belts located between the trench and the foreland. The thin-skinned, east-verging Precordillera of western Argentina accounts for 60-75% of the total shortening and formed mostly since major volcanism ceased at ˜10 Ma. Industry seismic reflection data show that the décollement of the Precordillera belt is located anomalously deep at ˜15 km. The belt is dominated by fault propagation folds and contains several prominent out-of-sequence thrust faults. Seismic stratigraphie analysis shows that Miocene strata in the Iglesia Valley, located between the Precordillera and the crest of the Andes, accumulated in a piggy-back basin. Onlap relations on the western side indicate that the High Cordillera was uplifted as a major fault bend fold over a buried ramp. Thrusting in the two western belts, both in the High Cordillera of Chile, formed during the waning stages of arc volcanism, 11-16 Ma. and account for 25-40% of the shortening. The observed shortening is probably greater than can be accounted for with reasonable crustal thicknesses, indicating the possibility of continental truncation or erosion along the plate margin or an anomalously thick root held down by the nearly flat subducted Nazca Plate. Our preferred crustal geometry puts the ramp between upper and lower crustal deformation west of the high topography, requiring crustal scale tectonic wedging to thicken the crust beneath the crest of the Andes. This non-unique model provides a simple explanation of the first order morphology of the Andes at this latitude.

  17. 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.

  18. 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

  19. On Darwin's footsteps across the Andes: Tithonian-Neocomian fossil invertebrates from the Piuquenes pass Tras las huellas de Darwin a través de los Andes: invertebrados fósiles del Tithoniano-Neocomiano del paso de Piuquenes

    Directory of Open Access Journals (Sweden)

    Beatriz Aguirre-Urreta

    2009-04-01

    Full Text Available The aim of this work is to summarize the modern knowledge of the geology of the Piuquenes Pass, in the Main Andes of Argentina and Chile, and to describe a small fauna of Tithonian-Neocomian invertebrates mostly represented by ammonites. The present knowledge of the region is compared with Darwin's, as expressed in his famous book on the Geology of South America.El objetivo de este trabajo es presentar una breve revisión moderna de la geología del Paso de Piuquenes en los Andes Principales de Chile y Argentina y describir una pequeña fauna de invertebrados del Tithoniano-Neocomiano compuesta principalmente por amonites. Se compara también el conocimiento de esta región con la referida por Darwin en su famoso libro sobre la geología de América del Sur.

  20. 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...

  1. Formalized morphostructural zoning of the mountain zone of the Andes

    Energy Technology Data Exchange (ETDEWEB)

    Gabrielov, A.M.; Gvishiani, A.D.; Zhidkov, M.P.

    1982-01-01

    A plan is presented for morphostructural zoning of the Andes compiled according to formalized signs for purposes of seismic forecasting. Characteristics are presented for the basic morphostructural subdivisions of the Andes.

  2. 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...

  3. 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.

  4. Paleomagnetism of Permian and Triassic rock, central Chilean Andes

    Science.gov (United States)

    Forsythe, Randall D.; Kent, Dennis V.; Mpodozis, Constantino; Davidson, John

    The first paleomagnetic data from Permian and Triassic formations west of the Andean divide are presented. Four formations of Permian or Triassic age in the central Chilean Andes have been investigated: two are located in the coastal ranges, and two are in the main cordillera. Of the formations in the main cordillera (Pastos Blancos and Matahuaico formations), only the Pastos Blancos Formation has yielded characteristic directions. While a fold test is absent, magnetizations are most likely secondary and yield pre-tilt corrected concordant inclinations, but yield declinations discordant 30° clockwise in comparison to the South American apparent polar wander path. Both formations from the coastal ranges (Cifuncho and Pichidangui formations) yielded stable directions. Postfolding magnetizations in the Cifuncho Formation also show declinations discordant 30° clockwise and concordant inclinations. The Pichidangui Formation has two stable components: one of postfolding age is concordant to apparent polar wander path data, and one of probable prefolding (Late Triassic) age is concordant in declination, but discordant in inclination. Further work is needed to better define the prefolding magnetizations in the Pichidangui Formation, but at present these preliminary results are the first paleomagnetic signs of displaced terranes along the Pacific margin of Chile. If correct, the results suggest that the Pichidangui Formation was some 15° of latitude farther south during the Late Triassic and had likely moved northward to its present latitudinal position with respect to cratonic South America by Middle to Late Jurassic.

  5. 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

  6. 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

  7. 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

  8. 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...

  9. 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...

  10. 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.

  11. The Structure of the Crust and Uppermost Mantle Beneath the Central Andes from Ambient Noise Tomography: Imaging the Neogene to Modern Batholith

    Science.gov (United States)

    Ward, K. M.; Zandt, G.; Beck, S. L.; Porter, R. C.; Wagner, L. S.; Minaya, E.; Tavera, H.

    2012-12-01

    The Central Andes of southern Peru, Bolivia, and northern Chile (between ~10°S and ~35°S) comprise the largest orogenic plateau in the world associated with abundant arc volcanism, the Central Andean Plateau (CAP). The goal of this continental-scale Ambient Noise Tomography (ANT) project is to incorporate broadband seismic data from ~20 seismic networks deployed incrementally in the Central and Southern Andes from May 1994 through March 2012, to image the vertically polarized shear-wave velocity (Vsv) structure of the CAP. First-order correlations with our shallow results (~5 km) and the morphotectonic provinces as well as subtler geological features indicate our results are robust. Our major results include mapping a pervasive mid-crustal low-velocity zone (images do not resolve a high conductivity anomaly across our low-velocity zone as expected in the presence of aqueous fluids or large interconnected zones of partial melt. Therefore, we dismiss them as likely explanations for our imaged low-velocity body outside of the APVC location. Working under the hypothesis that voluminous ignimbrites are the surface expression of batholith formation at depth as exemplified by the APVC, we combine our results with the locations of known Neogene ignimbrite eruptive centers and negative isostatic residual gravity anomalies and suggest the 3.25 km/s shear-wave velocity contour at 15 km depth generally outlines the extent of a Neogene to modern batholith, with isolated pockets of partial melt where velocities dip below 3.0 km/s. A velocity of 3.25 km/s at this pressure and temperature regime is too low for an isotropic granitic composition and must be explained without invoking significant partial melt. Previous work in Tibet, a region with thick crust analogous to the CAP, suggests a zone of mid-crustal radial anisotropy may separate horizontally and vertically polarized shear-wave velocities by as much as 20%. The effective isotropic shear velocity may be ~10% faster than

  12. 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.

  13. 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

  14. Complex brittle deformation pattern along the Southern Patagonian Andes (Argentina)

    Science.gov (United States)

    Barberón, Vanesa; Sue, Christian; Ronda, Gonzalo; Ghiglione, Matías

    2016-04-01

    The Southern Patagonian Andes is located in the southern extreme of the Pacific subduction zone, where the Antartic oceanic plate sinks underneath South America. The history of the area begins with compression during Paleozoic, Jurassic extension associated to the rift and opening of the South Atlantic Ocean, then a sag stage in the Lower Cretaceous followed by a foreland phase as a result of plate tectonics (Ghiglione et al., 2016). The kinematic study is concentrated in the Argentinean foothills, between 46°40' and 48° SL. We measured around 800 fault planes and their striaes with the sense of movement in order to characterize the stress field. The software used to make the stress inversion were Tensor (Delvaux, 2011) and Multiple Inverse Method MIM (Yamaji et al., 2011). The stress field map was built with the results of the MIM. We present new data from 48 sites located in the northern sector of the Southern Patagonian Andes. The measurements were made in several rocks from Paleozoic to Lower Cretaceous, even though most were taken in pyroclastic jurassic rocks from El Quemado Complex. Paleostress tensors obtained are mostly strike-slip, although a 25% is normal and there are a few compresional. The pattern of faults found is complex. In some sites the tensor can be locally linked to satellite images and observations from the field or be related to a major thrust front. There is no clear correlation between the age and/or lithology with the tensor since the youngest rocks measured are Lower Cretaceous. Probably there are several generations of family faults connected to different and recent tectonic phases then the paleostress tensors might correspond to the latest tectonic events.

  15. Agreement between the Government of the Republic of Chile and ESO for Establishing a New Center for Observation in Chile - ALMA

    Science.gov (United States)

    2002-10-01

    On October 21, 2002, the Minister of Foreign Affairs of the Republic of Chile, Mrs. María Soledad Alvear and the ESO Director General, Dr. Catherine Cesarsky , signed an Agreement that authorizes ESO to establish a new center for astronomical observation in Chile . This new center for astronomical observation will be for the Atacama Large Millimeter Array (ALMA) , the largest ground based astronomical project for the next decades. On this occasion, Minister Alvear stated that "we want to have ALMA working as soon as possible, which will constitute a pride not only to Chilean scientists but for the whole country and in particular, for the community of the Antofagasta Region" . ESO Director General Cesarsky said that "signing this agreement between the Government of Chile and ESO is a historical step in the astronomical collaboration between Chile and ESO and it will allow Chile to host, once again, a project of worldwide interest and impact" . ALMA is a joint project on equal basis between ESO and AUI (Associated Universities, Inc.). These organizations represent the scientific interests of Europe on one side and the United States with Canada on the other side. Chilean astronomers are closely involved with the project and 10% of the observing time will be reserved for Chilean science. ALMA will be built in the Andes, on the Plateau of Chajnantor (see the Chajnantor Photo Gallery ), 5000 metres above sea level and 60 km East of the town of San Pedro de Atacama. The array will be comprised of 64 antennas with unprecedent sensitivity and angular resolution that will allow studying the origin of galaxies, stars and planets, opening new horizons for astronomy, and being able to observe galaxies across the universe where stars are being formed. The agreement now signed between ESO and the Government of the Republic of Chile recognizes the interest that the ALMA Project has for Chile, as it will deepen and strengthen the cooperation in scientific and technological matters

  16. [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

  17. 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.

  18. 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...

  19. 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...

  20. 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.

  1. 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

  2. Stress patterns of the Plio-Quaternary brittle deformation along the Calama-Olacapato-El Toro Fault, Central Andes

    Science.gov (United States)

    Lanza, F.; Tibaldi, A.; Waite, G. P.; Corazzato, C.; Bonali, F.; Nardin, A.

    2012-04-01

    Understanding the geometry and kinematics of the major structures of an orogen is essential to elucidate its style of deformation, as well as its tectonic evolution. We describe the temporal and spatial changes in the state of stress of the trans-orogen area of the Calama-Olacapato-El Toro (COT) Fault Zone in the Central Andes, at about 24° S within the northern portion of the Puna Plateau between the Argentina-Chile border. The importance of the COT derives principally from the Quaternary-Holocene activity recognized on some segments, which may shed new light on its possible control on Quaternary volcanism and on the seismic hazard assessment of the area. Field geological surveys along with kinematic analysis and numerical inversion of ~ 280 new fault-slip measurements have revealed that this portion of the COT consists mainly of NW-SE striking faults, which have been reactivated under three different kinematic regimes: 1) a Miocene transpressional phase with the maximum principal stress (σ1) chiefly trending NW-SE; 2) an extensional phase that started by 9 Ma, with a horizontal NW-SE-trending minimum principal stress (σ3) - permutations between σ2 and σ3 axes have been recognized at three sites - and 3) a left-lateral strike-slip phase with an ~ ENE-WSW σ1 and a ~ NNW-SSE σ3 dating to the late Pliocene-Quaternary. Spatially, in the Quaternary, the left-lateral component decreases toward the westernmost tip of the COT, where it transitions to extension; this produced to a N-S horst and graben structure. Hence, even if trascurrence is still active in the eastern portion of the COT, as focal mechanisms of crustal earthquakes indicate, our study demonstrates that extension is becoming the predominant structural style of deformation, at least in the western region. These major temporal and spatial changes in the tectonic regimes are attributed in part to changes in the magnitude of the boundary forces due to subduction processes. The overall perpendicular

  3. 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 ...

  4. 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.

  5. 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).

  6. Managing hazardous pollutants in Chile: arsenic.

    Science.gov (United States)

    Sancha, Ana María; O'Ryan, Raul

    2008-01-01

    Chile is one of the few countries that faces the environmental challenge posed by extensive arsenic pollution, which exists in the northern part of the country. Chile has worked through various options to appropriately address the environmental challenge of arsenic pollution of water and air. Because of cost and other reasons, copying standards used elsewhere in the world was not an option for Chile. Approximately 1.8 million people, representing about 12% of the total population of the country, live in arsenic-contaminated areas. In these regions, air, water, and soil are contaminated with arsenic from both natural and anthropogenic sources. For long periods, water consumed by the population contained arsenic levels that exceeded values recommended by the World Health Organization. Exposure to airborne arsenic also occurred near several large cities, as a consequence of both natural contamination and the intensive mining activity carried out in those areas. In rural areas, indigenous populations, who lack access to treated water, were also exposed to arsenic by consuming foods grown locally in arsenic-contaminated soils. Health effects in children and adults from arsenic exposure first appeared in the 1950s. Such effects included vascular, respiratory, and skin lesions from intake of high arsenic levels in drinking water. Methods to remove arsenic from water were evaluated, developed, and implemented that allowed significant reductions in exposure at a relatively low cost. Construction and operation of treatment plants to remove arsenic from water first began in the 1970s. Beginning in the 1990s, epidemiological studies showed that the rate of lung and bladder cancer in the arsenic-polluted area was considerably higher than mean cancer rates for the country. Cancer incidence was directly related to arsenic exposure. During the 1990s, international pressure and concern by Chile's Health Ministry prompted action to regulate arsenic emissions from copper smelters. A

  7. 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

  8. 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.

  9. 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

  10. 2010 Chile Earthquake Aftershock Response

    Science.gov (United States)

    Barientos, Sergio

    2010-05-01

    The Mw=8.8 earthquake off the coast of Chile on 27 February 2010 is the 5th largest megathrust earthquake ever to be recorded and provides an unprecedented opportunity to advance our understanding of megathrust earthquakes and associated phenomena. The 2010 Chile earthquake ruptured the Concepcion-Constitucion segment of the Nazca/South America plate boundary, south of the Central Chile region and triggered a tsunami along the coast. Following the 2010 earthquake, a very energetic aftershock sequence is being observed in an area that is 600 km along strike from Valparaiso to 150 km south of Concepcion. Within the first three weeks there were over 260 aftershocks with magnitude 5.0 or greater and 18 with magnitude 6.0 or greater (NEIC, USGS). The Concepcion-Constitucion segment lies immediately north of the rupture zone associated with the great magnitude 9.5 Chile earthquake, and south of the 1906 and the 1985 Valparaiso earthquakes. The last great subduction earthquake in the region dates back to the February 1835 event described by Darwin (1871). Since 1835, part of the region was affected in the north by the Talca earthquake in December 1928, interpreted as a shallow dipping thrust event, and by the Chillan earthquake (Mw 7.9, January 1939), a slab-pull intermediate depth earthquake. For the last 30 years, geodetic studies in this area were consistent with a fully coupled elastic loading of the subduction interface at depth; this led to identify the area as a mature seismic gap with potential for an earthquake of magnitude of the order 8.5 or several earthquakes of lesser magnitude. What was less expected was the partial rupturing of the 1985 segment toward north. Today, the 2010 earthquake raises some disturbing questions: Why and how the rupture terminated where it did at the northern end? How did the 2010 earthquake load the adjacent segment to the north and did the 1985 earthquake only partially ruptured the plate interface leaving loaded asperities since

  11. 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.

  12. 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)

  13. Is Chile Complying with its Light Pollution Regulations? A Status Report

    Science.gov (United States)

    Smith, M. G.; Sanhueza, P.; Schwarz, H. E.; Walker, A. R.

    2005-12-01

    Monte Patria is the first Municipality in Chile to comply fully with Supreme Decree 686, the Chilean, environmentally-based legislation governing exterior lighting in Northern Chile - the "norma luminica". "Before" and "after" photographs of Monte Patria were published in last June's issue of "Physics Today", in the context of the global effort to control light pollution. Some photographs of other Chilean towns have been obtained for this poster and for display at the International Dark Sky Association's stand at this meeting. Highlights include detailed midnight and dawn panoramas taken by us during October, 2005 - the month in which the six-year "grace period" for all external lighting in northern Chile's astronomically-sensitive 2nd, 3rd and 4th Regions was supposed to come into full compliance. It is clear that significant progress is being made. The chief obstacle has been financial. Large-scale changeout of street lighting requires an outlay of many millions of dollars from cash-strapped municipalities. Chile's central government has moved in to provide financing at the 80-100/% level in many cases. Once Chile's congressional elections are over, we will be able to judge the political will to complete the changeover. Various large mining operations are currently engaged in major lighting changeovers; such changes are especially important in the various mines that are directly visible from existing major observatories in Northern Chile. The importance to astronomy is that full compliance with DS686 will, on average, extend the potential useful life of all the major optical observatories in Northern Chile by several decades. Funding for the Office for the Protection of the Quality of the Skies of Chile (OPCC) is provided by the Chilean National Environment Committee (CONAMA), NOAO, Gemini, ESO and the Las Campanas Observatory of the Carnegie Institute of Washington.

  14. 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...

  15. 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)

  16. 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

    Directory of Open Access Journals (Sweden)

    Alexis Castillo

    2011-11-01

    Full Text Available 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 CdThe contents of Zn, Cu, Cd, Pb, Fe, Al and Ni in the muscle tissue of Cancer polyodon from Caldera, Calderilla, Inglesa, and Salada bays (Atacama, Chile were quantified. The results were compared with similar studies by other authors and with the national and international regulatory standards for heavy metal contents in crustaceans for human consumption. In increasing order, the metal contents in C. polyodon were: Cd< Ni< Cu< Pb< Zn

  17. 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.

  18. 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.

  19. 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

  20. Contrasting climate change impact on river flows from high-altitude catchments in the Himalayan and Andes Mountains

    Science.gov (United States)

    Pellicciotti, Francesca

    2016-01-01

    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

  1. 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

  2. Chile: segundo tiempo Chile: Half-time

    Directory of Open Access Journals (Sweden)

    ROBERT L FUNK

    2009-01-01

    Full Text Available El artículo examina el año político chileno, ofreciendo un análisis crítico del concepto de 'segundo tiempo' autoimpuesto por la presidenta Michelle Bachelet a comienzos del 2008. Resumiendo algunas de las políticas implementadas, el trabajo cuestiona si se logró marcar una linea y dejar atrás los dos primeros y difíciles años del cuarto gobierno de la Concertación. Analizando las medidas tomadas y las encuestas de opinión pública, se encuentra que el reenfoque de las prioridades del gobierno y una complicada coyuntura externa ayudó a levantar los niveles de apoyo de la presidenta y su gobierno.The article examines the political year in Chile, offering a critical analysis of the concept of 'Second Period' which President Michelle Bachelet defined at the beginning of 2008. Summarising some of the policies implemented, the piece asks whether the government was able to draw a line, leaving behind the first, difficult two years of the Concertación s fourth government. Analyzing the measures taken and public opinion polls, the paper finds that a re-focussing of the government's priorities together with a complicated external environment helped to raise support for the president as well as her government.

  3. 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...

  4. 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.

  5. 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.

  6. 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...

  7. 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.

  8. 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...

  9. 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

  10. Screening for new accumulator plants in Andes Range mines

    Science.gov (United States)

    Bech, Jaume; Roca, Núria

    2016-04-01

    accumulated considerable concentrations of Cu and Zn. The species from the genus Bidens (Asteraceae) were able not only to accumulate high shoot As concentrations (> 1000 μg g-1 in B. cynapiifolia from Peru) but also considerable amounts of Pb (B. humilis from Chile). The highest Cu shoot concentrations were found in Mullinum spinosum (870 μg g-1) and in B. cynapiifolia (620 μg g-1). The shoot accumulation of Zn was highest in Baccharis amdatensis (>1900 μg g-1) and in Rumex crispus (1300 μg g-1) from the Ag mine in Ecuador (Bech et al., 2002). In the Peruvian Andes, B. triplinervia can be considered interesting for phytostabilization, due to its capacity to restrict the accumulation of elevated amounts of Pb and Zn in the shoots.

  11. 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...

  12. A DRONE FLIGHT OVER PARANAL, CHILE

    CERN Multimedia

    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.

  13. 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

  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. Protection of Existing and Potential Astronomical Sites in Chile - an Update.

    Science.gov (United States)

    Smith, M. G.; Sanhueza, P.; Norman, D.; Schwarz, H.; Orellana, D.

    2002-12-01

    The IAU's Working Group on Controlling Light Pollution (iauwg) has declared Mauna Kea and a wide strip of Northern Chile between Antofagasta and Chajnanator as top priorities for its efforts to protect existing and potential sites in the Northern and Southern hemispheres respectively. This report provides an update on the iauwg's co-ordinated efforts to protect areas around the major international optical observatories in Chile, as well as the "Chilean Special Zone" (CSZ) mentioned above. This zone is of current and potential interest for the installation of extremely large optical telescopes and includes the ALMA radio-astronomy site. The CSZ is potentially vulnerable to adverse effects of mining in the region. Progess has been made in demonstrating to local mining interests within the CSZ the economic advantages of quality lighting. Educational and outreach activities to a variety of target audiences are building on legislation covering dark skies - itself part of work by the Chilean government to protect the natural heritage of Chile. Substantial good will was generated by an international, bilingual conference held last March in Chile. Just in the region around AURA's Observatory in Chile (Gemini South, CTIO and SOAR), a portable planetarium has been used to reach out to over 600 teachers and 65,000 pupils in the RedLaSer schools network within the last three years. This has attracted the direct interest of Chile's Ministry of Education. Videoconferencing over Internet2 is being used for educational purposes between Chile and various sites in the US. The NSF- initiated Mamalluca municipal observatory now receives more visitors than all the international observatories in Chile combined and is the focus of an expanding local industry of astronomical eco-tourism. Most of this work was supported by funding from, or via, the US NSF through CTIO and Gemini, and from ESO, OCIW, CONAMA and the IDA.

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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

  1. Lung cancer and arsenic exposure in drinking water: a case-control study in northern Chile Cáncer de pulmón y exposición a arsénico en el agua potable: un estudio de casos y controles en el norte de Chile

    Directory of Open Access Journals (Sweden)

    Catterina Ferreccio

    1998-01-01

    Full Text Available In some Chilean cities, levels of arsenic (As in drinking water reached 800 µg/L between 1950 and 1970, while current levels are 40 µg/L. To evaluate the causal role of this exposure in lung and bladder cancers, we conducted a case-control study in Regions I, II, and III of the country. From 1994 to 1996, cases diagnosed as lung cancer and two hospital controls were entered in the study; one control was a patient with a cancer, while the other was a patient without cancer, both conditions unrelated to As. Controls were matched with cases by age and sex. A standard survey containing questions about residence, employment, health history, was administered to study subjects. Data on As concentrations in water were obtained from records of the municipal water companies. A total of 151 lung cancer cases and 419 controls (167 with cancer and 242 without cancer were enrolled. Median level of lifetime As exposure was significantly higher among cases, with a clear dose-response relationship between mean As exposure levels, with an OR (95% CI of: 1, 1.7 (0.5-5.1, 3.9 (1.2-13.4, 5.5 (2.2-13.5, and 9.0 (3.6-22 for strata one to five respectively. This study provides new evidence that As in drinking water can cause internal cancers and gives an estimate of the form of this relationship.En algunas ciudades de Chile, entre 1950 y 1970, los niveles de arsénico (As en el agua potable alcanzaron los 800 µg/l, estando hoy en 40 µg/l; para evaluar el rol de esta exposición, se llevó a cabo este estudio de casos de cáncer de pulmón y controles en las Regiones I, II y III. Entre 1994 y 1996, se ingresaron casos de cáncer de pulmón y dos controles hospitalarios: un control, un paciente con cáncer y el otro, un paciente sin cáncer, ambos diagnósticos no relacionados con arsénico. Los controles fueron pareados grupalmente por edad y sexo con los casos. A cada sujeto, se le aplicó una encuesta estandarizada sobre residencia, empleo y salud. La informaci

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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...

  7. 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...

  8. 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...

  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 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...

  11. 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...

  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 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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

  20. Gravity Wave and Turbulence Transport of Heat and Na in the Mesopause Region over the Andes

    Science.gov (United States)

    Guo, Yafang; Liu, Alan Z.

    2016-07-01

    The vertical heat and Na fluxes induced by gravity waves and turbulence are derived based on over 600 hours of observations from the Na wind/temperature lidar located at Andes lidar Observatory (ALO), Cerro Pachón, Chile. In the 85-100 km region, the annual mean vertical fluxes by gravity waves show downward heat transport with a maximum of 0.78K m/s at 90 km, and downward Na transport with a maximum of 210 m/s/cm3 at 94km. The maximum cooing rate reaches -24 K/d at 94km. The vertical fluxes have strong seasonal variations, with large differences in magnitudes and altitudes of maximum fluxes between winter and summer. The vertical fluxes due to turbulence eddies are also derived with a novel method that relates turbulence fluctuations of temperature and vertical wind with photon count fluctuations at very high resolution (25 m, 6 s). The results show that the vertical transports are comparable to those by gravity waves and they both play significant roles in the atmospheric thermal structure and constituent distribution. This direct measure of turbulence transport also enables estimate of the eddy diffusivity for heat and constituent in the mesopause region.

  1. New and Evolving Seismic Images of the Central Andes and Subducting Nazca Slab: 20 Years of Portable Seismology Results

    Science.gov (United States)

    Beck, S. L.

    2014-12-01

    Beno Gutenberg first identified a seismic low velocity zone in the upper mantle that we now refer to as the asthenosphere that is still the focus of many studies in active tectonic regions. The upper-most mantle is very heterogeneous and occupies the depth range where much of the tectonic action occurs especially in subduction zones and convergent margins. The central South American convergent margin is the result of the subduction of the Nazca Plate beneath the South American Plate and includes the Andes, one of the largest actively growing mountain ranges on Earth. The South American subduction zone has two regions of "flat" subduction in Peru and central Chile and Argentina separated by a segment of "normal" subduction and an active magmatic arc. The central Andean plateau has an average elevation of 3-4 km and some of the thickest crust on Earth with deformation reaching ~800 km inland. This active margin is characterized by along-strike variations in magmatism, upper crustal shortening, crustal thickness, and slab geometry that make it an ideal region to study the relationship between the subducting slab, the mantle wedge, and the overriding plate. After 20 years of portable seismic deployments in the Central Andes seismologists have generated unprecedented seismic images spanning ~3000 km of the Andean lithosphere, the subducting Nazca slab, and the surrounding mantle. Seismic travel-time, ambient noise and earthquake surface-wave tomography, receiver function imaging, and joint receiver function - surface wave dispersion inversions have produced along strike images of the Central Andes from the surface to a depth of ~700 km. These new images were made possible by PI-driven portable broadband seismic deployments and data sharing by many international groups. I will highlight images of along-strike variations in crustal properties and thickness, mantle lithospheric structure, and slab geometry. These seismic images allow us to more completely evaluate the role

  2. Escondida Mine, Chile

    Science.gov (United States)

    2002-01-01

    Full resolution visible and near-infrared image (1.4 MB) Full resolution shortwave infrared image (1.6 MB) This Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image covers 30 by 23 km (full images 30 x 37 km) in the Atacama Desert, Chile, and was acquired on April 23, 2000. The Escondida copper, gold, and silver open-pit mine is at an elevation of 3050 m, and began operations in 1990. Current capacity is 127,000 tons/day of ore; in 1999 production totaled 827,000 tons of copper, 150,000 ounces of gold, and 3.53 million ounces of silver. Primary concentrate of the ore is done on-site; the concentrate is then sent to the coast for further processing through a 170 km long, 9-inch pipe. Escondida is related geologically to three porphyry bodies intruded along the Chilean West Fissure Fault System. A high grade supergene cap overlies primary sulfide ore. The top image is a conventional 3-2-1 (near infrared, red, green) RGB composite. The bottom image displays shortwave infrared bands 4-6-8 (1.65um, 2.205um, 2.33um) in RGB, and highlights the different rock types present on the surface, as well as the changes caused by mining. Image courtesy NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

  3. Country watch: Chile.

    Science.gov (United States)

    Montoya Leiva, M

    1996-01-01

    Servicio Paz y Justicia (SERPAJ) is a nongovernmental organization (NGO) established in Chile in 1977. It supports fundamental human dignity and rights by fighting discrimination and exclusion based upon individual differences. SERPAJ promotes training, organization, and the political participation of community members as part of the democratic process, working mainly with the at risk women, street children, and youth of Santiago's working-class neighborhoods. Groups participate in workshops and training courses on human rights and development, civic education, and methods of non-violent community action. In 1987, SERPAJ-Sur Oriente began to include the topic of sexuality and AIDS/STDs in courses training working-class women as community human rights agents. The NGO is therefore one of the first mainstream Chilean human rights organizations to incorporate HIV/AIDS issues. A basic facts brochure was developed, followed by a pilot education project developed in one neighborhood which was then systematically replicated in other neighborhoods. The comments of some people who have participated in SERPAJ workshops are presented.

  4. 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/.

  5. Modernitet og forbrugskultur i Chile

    DEFF Research Database (Denmark)

    Cristoffanini, Pablo Rolando

    2012-01-01

    I de sidste årtier er Chile blevet et egentligt forbrugersamfund. Udbredelsen af forbrugskulturen og forbrugerismen er centrale fænomener i chilenernes dagligliv og har nået et omfang, som har konsekvenser for de borgere, der ikke kan deltage fuldt ud heri, noget som er typisk for et samfund med en...... ujævn økonomisk udvikling og med store sociale forskelle. Denne proces er ikke et produkt af en stille, fredelig og naturlig samfundsudvikling, således som magteliten og de toneangivende intellektuelle i Chile har fremstillet det. Som jeg vil vise, er skabelsen af et egentlig forbrugssamfund knyttet til...... til i dag. Ifølge disse er Chile blevet et moderne samfund netop i kraft af, at Chile er et ægte forbrugersamfund med alt, hvad dette indebærer, såvel materielt som symbolsk. For det tredje er billedet af Chile som en ”supermoderne” nation i den latinamerikanske kontekst en udbredt forestilling hos...

  6. It Pays to Invest in Chile

    Institute of Scientific and Technical Information of China (English)

    Li Zhen

    2011-01-01

    @@ Chile is the first country to establish coopera-tive relations with China in South America, and also the first one to support China's ac-cession to the World Trade Organization.In 2005, Chile and China signed a free trade agreement.After that, China has become Chile's largest trad-ing partner, and Chile become China's second largest partner in South America.

  7. 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

  8. The first ANDES elements: 9-DOF plate bending triangles

    Science.gov (United States)

    Militello, Carmelo; Felippa, Carlos A.

    1991-01-01

    New elements are derived to validate and assess the assumed natural deviatoric strain (ANDES) formulation. This is a brand new variant of the assumed natural strain (ANS) formulation of finite elements, which has recently attracted attention as an effective method for constructing high-performance elements for linear and nonlinear analysis. The ANDES formulation is based on an extended parametrized variational principle developed in recent publications. The key concept is that only the deviatoric part of the strains is assumed over the element whereas the mean strain part is discarded in favor of a constant stress assumption. Unlike conventional ANS elements, ANDES elements satisfy the individual element test (a stringent form of the patch test) a priori while retaining the favorable distortion-insensitivity properties of ANS elements. The first application of this formulation is the development of several Kirchhoff plate bending triangular elements with the standard nine degrees of freedom. Linear curvature variations are sampled along the three sides with the corners as gage reading points. These sample values are interpolated over the triangle using three schemes. Two schemes merge back to conventional ANS elements, one being identical to the Discrete Kirchhoff Triangle (DKT), whereas the third one produces two new ANDES elements. Numerical experiments indicate that one of the ANDES element is relatively insensitive to distortion compared to previously derived high-performance plate-bending elements, while retaining accuracy for nondistorted elements.

  9. 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.……

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. Women and Politics in Chile.

    Science.gov (United States)

    Kirkwood, Julieta

    1983-01-01

    Political parties in Chile of both the left and right have focused more on drawing women into their ideologies than on considering what political issues mean to women. A look at feminist thought shows how political life for women includes not only the traditional political arena but also domestic life. (IS)

  18. 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

  19. 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 ...

  20. A dynamical analysis of the seismic activity of Villarrica volcano (Chile) during September-October 2000

    Energy Technology Data Exchange (ETDEWEB)

    Tarraga, Marta [Departamento de Volcanologia. Museo Nacional de Ciencias Naturales, CSIC, Madrid (Spain)], E-mail: martat@mncn.csic.es; Carniel, Roberto [Dipartimento di Georisorse e Territorio, Universita di Udine, Via Cotonificio 114, 33100 Udine (Italy)], E-mail: roberto.carniel@uniud.it; Ortiz, Ramon; Garcia, Alicia [Departamento de Volcanologia. Museo Nacional de Ciencias Naturales, CSIC, Madrid (Spain); Moreno, Hugo [Observatorio Volcanologico de los Andes del Sur (OVDAS), Servicio Nacional de Geologia y Mineria de Chile (SERNAGEOMIN), Temuco, IX Region (Chile)

    2008-09-15

    Although Villarrica volcano in Chile is one of the most active in the southern Andes, the literature studying its seismic activity is relatively scarce. An interesting problem recently tackled is the possibility for a regional tectonic event to trigger a change in the volcanic activity of this basaltic to basaltic-andesitic volcano, which is in turn reflected in the time evolution of the properly volcanic seismicity, especially in the form of a continuous volcanic tremor. In this work, we conduct a spectral, dynamical and statistical analysis of the tremor recorded during September and October 2000, in order to characterize the anomalous behaviour of the volcano following a tectonic event recorded on 20th September 2000. The observed dynamical transitions are compared with remote sensing and visual observations describing the changes in the eruptive style of the volcano.

  1. 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

  2. Clinical and Demographical Characteristics of Patients with Medication Overuse Headache in Argentina and Chile

    DEFF Research Database (Denmark)

    Shand, Beatriz; Goicochea, Maria Teresa; Valenzuela, Raul;

    2015-01-01

    BACKGROUND: Data on the characteristics of Medication Overuse Headache (MOH) in Latin American (LA) are scarce. Here we report the demographic and clinical features of the MOH patients from Argentina and Chile enrolled in the multinational COMOESTAS project in the period 2008-2010. METHODS: The LA...... population was formed by 240 MOH subjects, 110 from Chile and 130 from Argentina, consecutively attending the local headache centres. In each centre, specifically trained neurologist interviewed and confirmed the diagnosis according to the ICHD-II criteria. A detailed history was collected on an electronic......, where it affects mostly women, in the most active decades of life. Some differences emerge as regards the demographic and clinical characteristics of MOH in this population as compared to Europe or Northern America. What seems more worrying about MOH in Argentina and Chile is that most patients overuse...

  3. Out of the Andes: patterns of diversification in clearwing butterflies.

    Science.gov (United States)

    Elias, M; Joron, M; Willmott, K; Silva-Brandão, K L; Kaiser, V; Arias, C F; Gomez Piñerez, L M; Uribe, S; Brower, A V Z; Freitas, A V L; Jiggins, C D

    2009-04-01

    Global biodiversity peaks in the tropical forests of the Andes, a striking geological feature that has likely been instrumental in generating biodiversity by providing opportunities for both vicariant and ecological speciation. However, the role of these mountains in the diversification of insects, which dominate biodiversity, has been poorly explored using phylogenetic methods. Here we study the role of the Andes in the evolution of a diverse Neotropical insect group, the clearwing butterflies. We used dated species-level phylogenies to investigate the time course of speciation and to infer ancestral elevation ranges for two diverse genera. We show that both genera likely originated at middle elevations in the Andes in the Middle Miocene, contrasting with most published results in vertebrates that point to a lowland origin. Although we detected a signature of vicariance caused by the uplift of the Andes at the Miocene-Pliocene boundary, most sister species were parapatric without any obvious vicariant barrier. Combined with an overall decelerating speciation rate, these results suggest an important role for ecological speciation and adaptive radiation, rather than simple vicariance.

  4. Andes hantavirus variant in rodents, southern Amazon Basin, Peru.

    Science.gov (United States)

    Razuri, Hugo; Tokarz, Rafal; Ghersi, Bruno M; Salmon-Mulanovich, Gabriela; Guezala, M Claudia; Albujar, Christian; Mendoza, A Patricia; Tinoco, Yeny O; Cruz, Christopher; Silva, Maria; Vasquez, Alicia; Pacheco, Víctor; Ströher, Ute; Guerrero, Lisa Wiggleton; Cannon, Deborah; Nichol, Stuart T; Hirschberg, David L; Lipkin, W Ian; Bausch, Daniel G; Montgomery, Joel M

    2014-02-01

    We investigated hantaviruses in rodents in the southern Amazon Basin of Peru and identified an Andes virus variant from Neacomys spinosus mice. This finding extends the known range of this virus in South America and the range of recognized hantaviruses in Peru. Further studies of the epizoology of hantaviruses in this region are warranted.

  5. Rapid millennial-scale vegetation changes in the tropical Andes

    NARCIS (Netherlands)

    D.H. Urrego; H. Hooghiemstra; O. Rama-Corredor; B. Martrat; J.O. Grimalt; L. Thompson

    2015-01-01

    We compare eight pollen records reflecting climatic and environmental change from the tropical Andes. Our analysis focuses on the last 50 ka, with particular emphasis on the Pleistocene to Holocene transition. We explore ecological grouping and downcore ordination results as two approaches for extra

  6. 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

  7. El alto de Copahue - Pino Hachado y la fosa de Loncopué: un comportamiento tectónico episódico, Andes neuquinos (37º - 39ºS The Copahue-Pino Hachado high and the Loncopuè trough: An episodic tectonic behaviour, Neuquén Andes (37º- 39ºS

    Directory of Open Access Journals (Sweden)

    E. García Morabito

    2005-12-01

    Full Text Available Los Andes de la parte central de Neuquén (38º-39ºS, enmarcados en los Andes Centrales Australes (35º-39ºS, han poseído una cronología de levantamiento similar al resto de los Andes Patagónicos Septentrionales (39º-46ºS construyéndose a través de sucesivas fases de alzamiento en el Cretácico medio, Eoceno medio y Mioceno superior. Sin embargo, se han diferenciado con respecto al resto de los Andes Patagónicos, ubicados hacia el sur, en lo relativo a las distintas fases de relajamiento extensional que han sufrido, tanto en el Oligoceno superior como en el Plio-Cuaternario. Existen evidencias que sugieren un comportamiento episódico de la faja plegada y corrida neuquina dado por regímenes tectónicos compresivos seguidos por estadios de extensión generalizados al menos desde el Cretácico medio. El estudio de dos unidades morfoestructurales desarrolladas entre los 37º y los 39ºS ejemplifican este comportamiento peculiar, el alto de Copahue - Pino Hachado ubicado en la zona limítrofe argentino-chilena y su extensión hacia el norte en territorio chileno, en la laguna de la Laja, y la fosa de Loncopué en el retroarco. El estudio de la estructura miocena a cuaternaria y la descripción detallada de la estratigráfía de este sector cordillerano han aportado un nuevo cuadro de evolución para este sector de los Andes.The Andes located in the central Neuquén (38º-39ºS, which belong to the southern Central Andes (35º-39ºS, have recorded a similar chronology of uplift than the neighbor northern Patagonian Andes (39º-46ºS. Both areas have been formed trough successive phases of contraction in the Late Cretaceous, Middle Eocene and Late Miocene respectively. However, the Neuquén Andes have experienced two discrete phases of orogenic relaxation, during the Late Oligocene and Pliocene-Quaternary, which make then distinctive respect to the area located to the south. Field studies have shown new evidences of an episodic behavior of

  8. Reasons for an outstanding plant diversity in the tropical Andes of Southern Ecuador

    Directory of Open Access Journals (Sweden)

    Michael Richter

    2009-06-01

    Full Text Available Long-term field studies in the scope of a multidisciplinary project in southern Ecuador revealed extraordinary high species numbers of many organismic groups. This article discusses reasons for the outstanding vascular plant diversity using a hierarchical scale-oriented top-down approach (Grüninger 2005, from the global scale to the local microscale. The global scale explains general (paleo- ecological factors valid for most parts of the humid tropics, addressing various hypotheses and theories, such as the “greater effective evolutionary time”, constant input of “accidentals”, the “seasonal variability hypothesis”, the “intermediate disturbance hypothesis”, and the impact of soil fertility. The macroscale focuses on the Andes in northwestern South America. The tropical Andes are characterised by many taxa of restricted range which is particularly true for the Amotape-Huancabamba region, i.e. the so called Andean Depression, which is effective as discrete phytogeographic transition as well as barrier zone. Interdigitation of northern and southern flora elements, habitat fragmentation, geological and landscape history, and a high speciation rate due to rapid genetic radiation of some taxa contribute to a high degree of diversification. The mesoscale deals with the special environmental features of the eastern mountain range, the Cordillera Real and surrounding areas in southern Ecuador. Various climatic characteristics, the orographic heterogeneity, the geologic and edaphic conditions as well as human impact are the most prominent factors augmenting plant species diversity. On microscale, prevailing regimes of disturbance and environmental stresses, the orographic basement, as well as the general role on the various mountain chains are considered. Here, micro-habitats e.g. niches for epiphytes, effects of micro-relief patterns, and successions after small-sized disturbance events are screened. Direct effects of human impact are

  9. A statistical study of Weinmannia pollen trajectories across the Andes

    Directory of Open Access Journals (Sweden)

    C. F. Pérez

    2009-10-01

    Full Text Available Recent airborne pollen records data from Northern Patagonia (San Carlos de Bariloche, Argentina, Lat. 41.1435° S, Long. 71.375° W, 800 m elevation suggest that pollen transport takes place from the west to the east slope of the Andes. However, the atmospheric characteristics responsible of this transport have not yet been studied. The aim of this paper is to assess potential source areas and to describe the involved atmospheric mechanisms of the trans-Andean pollen transport. Methodology relies on the analysis of backward trajectories of air masses calculated with the HYSPLIT 4.9 regional model for particular days where airborne pollen of Weinmannia trichosperma Cav. was detected east of the Andes. This pollen type was selected because it is found regularly at localities in eastern Patagonia beyond its present-day distribution. Weinmannia's substantial presence during early Holocene times would also benefit from better knowledge of its transport mechanisms. Correspondence between atmospheric trajectories and the position of sources was checked using GIS maps. Mode T, Principal Component Analysis (PCA with Varimax rotation was used to identify the main spatial structure of geopotential height anomalies producing the calculated trajectories. Eighty-eight cases showed that the calculated directions of trajectories trended from the Northwest to Southwest passing over the Chilean region of W. trichosperma distribution. PCs results showed two patterns of negative anomalies over southern Patagonia. The prevailing circulation pattern which drives airborne transport is the presence of a trough located south of 37 to 40° S with its axis over western Patagonia. The synoptic situations for two cases highly correlated with principal component scores were described.

  10. ALMA communication backbone in Chile goes optical

    Science.gov (United States)

    Filippi, G.; Ibsen, J.; Jaque, Sandra; Liello, F.; Navarro, C.

    2014-07-01

    High-bandwidth communication has become a key factor for scientific installations as Observatories. This paper describes the technical, organizational, and operational goals and the level of completion of the ALMA Optical Link Project. The project focus is the creation and operation of an effective and sustainable communication infrastructure to connect the ALMA Observatory, located in the Atacama Desert, in the Northern region of Chile, with the point of presence in ANTOFAGASTA, about 400km away, of the EVALSO infrastructure, and from there to the Central Office in the Chilean capital, Santiago. This new infrastructure that will be operated in behalf of ALMA by REUNA, the Chilean National Research and Education Network, will use state of the art technologies, like dark fiber from newly built cables and DWDM transmission, allowing extending the reach of high capacity communication to the remote region where the Observatory is located. When completed, the end-to-end Gigabit-per-second (Gbps) capable link will provide ALMA with a modern, effective, robust, communication infrastructure capable to cope with present and future demands, like those coming from fast growing data transfer to rapid response mode, from remote monitoring and engineering to virtual presence.

  11. Acuicultura Insostenible en Chile (Unsustainable aquaculture in Chile

    Directory of Open Access Journals (Sweden)

    Sommer, Marcos

    2009-03-01

    Full Text Available ResumenLa acuicultura en Chile sólo será alternativa a la pesca si se consigue llevar su producción a parámetros de sostenibilidad, no solamente económica sino, fundamentalmente, ambiental. Con un esfuerzo dirigido hacia medidas legislativas y de control, e investigación aplicada, podríamos acercarnos a una acuicultura ambientalmente sostenible.

  12. The Plutón Diorítico Moat: Mildly alkaline monzonitic magmatism in the Fuegian Andes of Argentina

    Science.gov (United States)

    González Guillot, M.; Escayola, M.; Acevedo, R.; Pimentel, M.; Seraphim, G.; Proenza, J.; Schalamuk, I.

    2009-12-01

    The Plutón Diorítico Moat (Moat Dioritic Pluton, PDM) is the largest of several isolated Cretaceous plutons exposed in the Fuegian Andes of Argentina. It is made of a large variety of rock types ranging from ultramafic bodies (pyroxenites and hornblendites) to syenites. The petrological diversity is thought to have been originated by fractional crystallization of a mantle-derived magma combined with minor assimilation of continental crust (AFC). Its geochemical characteristics indicate a mildly-alkaline monzonitic affinity, contrasting with the typical calc-alkaline plutons of the Southern Patagonian Batholith (PB) to the south, in the Chilean archipelago. The PDM original magma is arc-related and its crystallization, as indicated by the Rb-Sr mineral isochron age of 115 ± 3 Ma, is coeval with some plutons of the PB. Therefore a similar tectonic regime is assumed for the emplacement of these plutonic bodies, both south and north of the Beagle channel. Differences in magma sources and degree of partial melting are inferred to account for the contrasting lithological and geochemical characteristics of the PB and PDM. The data suggest that the original magmas of the PDM were generated at greater depths in the mantle, by a smaller degree of partial melting, compared with the PB. The Barros Arana basalts, exposed to the north in Chile, forming a back-arc volcanic complex, display the same mildly-alkaline shoshonitic affinity, and are considered in this study as the volcanic equivalents of the PDM. All the plutons in the Argentinean Fuegian Andes display similar lithological and geochemical characteristics and are, therefore, grouped in this work under the name of Magmatismo Potásico Fueguino ( Fuegian Potassic Magmatism).

  13. [Concentration of trace elements in children from northern Chile].

    Science.gov (United States)

    Peña Clunes, L; Jamett, A; Santander, M; Gras, N; Muñoz, L

    1992-01-01

    Industrial processes may lead to severe alterations of environment affecting the health and quality of life of neighbouring communities. The present study reports the concentrations of Cu, As, Br, Na, K, Se, Hg, Cr, Co, Zn, Fe and Sb in samples of hair from children 6 years of age living in Antofagasta, Chuquicamata, María Elena, Calama and San Pedro de Atacama. Results were compared to those obtained in children of the same age living in Santiago. Samples were obtained according to recommendations from the International Nuclear Energy Organization and were analyzed by the neutron activation method at facilities of the Chilean Nuclear Energy Commission. Values for Cu (38.8 ppm), Cr (4.29 ppm) and As (19.2 ppm) in children from Chuquicamata are considered dangerous according to international standards.

  14. Protecting the Local Dark-Sky Areas around the International Observatories in Chile.

    Science.gov (United States)

    Smith, M. G.

    2001-12-01

    This report covers efforts by IAU Commission 50's new Working Group on Light Pollution to slow or halt the spread of incipient light pollution near the VLT, the Magellan 6.5m telescopes, Gemini South, SOAR, Blanco and many smaller telescopes in Chile. An effort has just begun to protect the ALMA site in Northern Chile from RFI. Such work includes extensive outreach programs to the local population, schools and industry as well as to local, regional and national levels of government in Chile. The group is working internationally with such organizations as the IDA; one member has recently led the production of "The first world atlas of the artificial night-sky brightness". These efforts have resulted in the first national-level environmental legislation covering dark skies as part of a government effort to protect the environment. Chilean manufacturers are now producing competitive, full-cut-off, street lighting designed specifically to comply with the new legislation. The Chilean national tourism agency is supporting "Astronomical Tourism" based on the dark, clear skies of Chile. An international conference on Controlling Light Pollution and RFI will be held in La Serena, Chile on 5-7 March, 2002, backed up by a parallel meeting of Chilean amateur astronomers. Much work remains to be done. Most of this work is supported by funding from the US National Science Foundation through CTIO, and from ESO, OCIW and CONAMA.

  15. The AURA Observatory in Chile - part of the IAU/UNESCO Extended Case Study.

    Science.gov (United States)

    Smith, Malcolm G.; Smith, R. Chris; Sanhueza, Pedro

    2015-08-01

    This talk discusses the Extended Case Study for AURA-O as a “Window to the Universe”http://www2.astronomicalheritage.net/index.php/show-entity=59&idsubentity=5That study was prepared in the context of supporting the desire to preserve humanity’s scientific/cultural heritage of outstanding, high-mountain, ground-based, observatory sites developed over the period 1870-2000. AURA-O includes the Cerro Tololo InterAmerican Observatory (CTIO), established in 1962 as the first of the major international observatories to be installed in Chile. The future of AURA-O now includes the Large Synoptic Survey Telescope (LSST).This Extended Case Study has provided the context for the development of possible initiatives to protect a variety of sites in Chile for their historical and scientific value to humanity. The dark skies and ideal weather patterns of northern Chile, along with its location in the southern hemisphere, have made this area of the world a major centre for astronomical facilities.While this talk will touch on the importance of dark skies as part of the Windows to the Universe concept, it is anticipated that others will be discussing (in FM2 and/or FM21) the current status and future plans (of the Chilean Government and the observatories) for protecting the dark skies of northern Chile.

  16. 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...... socialistiske regeringer har accepteret et begrænset demokrati og videreført en nyliberal økonomisk politik, der har bragt dem på konfrontationskurs med massebevægelserne og isoleret Chile fra de andre lande i regionen, der søger integration og gensidig støøte. Udgivelsesdato: Februar...

  17. [The epidemiological transition in Chile].

    Science.gov (United States)

    Albalá, C; Vio, F; Robledo, A; Icaza, G

    1993-12-01

    Aiming to describe the place that Chile has in the epidemiological transition, a descriptive study of the changes in demographic and epidemiological profiles of the country during the last 30 years is presented. The important decrease in general and child mortality rates, that has lead to an increase in life expectancy and ageing of the population, is emphasized. A 82% reduction in the proportion of deaths among less than one year old children and a 62% increase in mortality among people 65 years or older is observed. In agreement with these changes, non transmissible chronic diseases appear as the principal cause of mortality (65% of all deaths). However, regarding morbidity, an increase in digestive infectious and sexually transmitted diseases and a decrease in immuno-preventable diseases, excepting measles, is noted. It is concluded that, according to mortality, Chile is in a post transition stage, but there is persistence of some infectious diseases, typical of a pre-transition stage. PMID:8085073

  18. Detailed Axial Morphology of the Chile Rise as it Approaches the Chile Triple Junction

    Science.gov (United States)

    Blackman, D. K.; Henig, A. S.; Barroso, E.; Grevemeyer, I.; Thurber, A. R.; German, C. R.; Inspire Cruise Participants, T.

    2010-12-01

    New bathymetric mapping along the two southernmost Chile Rise spreading segments shows axial volcanic structure that had not been evident in prior data. On the first segment extending north from the triple junction, where the basement is not obscured by sediment, a narrow line of volcanic structures appears to track the center of the rift valley. However, the next segment north, which is offset almost 50 km along a transform fault, has axial volcanic features that vary in position within the rift valley. In the northern ~half of this segment, lineated small volcanic structures hug the eastern scarp of the rift whereas in the south they are apparent only along the western part of the valley floor. A classic ridge-transform intersection (RTI) nodal deep occurs at this southern end of the segment. The position of the basin is asymmetric relative to the axis, toward the ‘inside corner’ on the eastern side of the rift valley. It is intriguing that the nodal deep, which is often modeled as the result of viscous mantle upwelling and plate stresses at an RTI, is centered on the opposite side of the rift valley from where the most recent volcanic activity occurred. Presumably this reflects interplay between local magma plumbing and tectonic stresses. In addition to the local ridge-transform forces, regional factors associated with subduction along the edge of the Cocos plate may affect mantle flow, melting, and detailed plate kinematics. We will present maps that combine the new Simrad EM122 swath sonar data, obtained during cruise MV1003 aboard R/V Melville, with pre-existing German and Chilean bathymetric grids. We will also discuss some of the tectonic and magmatic implications of the observed detailed morphologic patterns. As one of the few areas on the globe where active subduction and spreading occur in close proximity, the southernmost Chile rise presents a natural laboratory for studying the manifestations of interaction between these processes.

  19. Miedo y represionpolitica en Chile

    OpenAIRE

    Amado M. Padilla; Lillian Comas Díaz

    1987-01-01

    This paper describes a human rights fact-finding mission to Chile concerned with the use of psychological techniques employed in offlcia- Uy sactioned torture and repressíon, Meetings and interviews were conducted with representatives of many organízatíons working with víctima of governrnental repression including the Chílean Psychological Assocíation. Fear and repression wene found to be widespread among all socioeconomic segments of the population. Physical and psychologic...

  20. The high Andes, gene flow and a stable hybrid zone shape the genetic structure of a wide-ranging South American parrot

    Directory of Open Access Journals (Sweden)

    Schaefer H Martin

    2011-06-01

    Full Text Available Abstract Background While the gene flow in some organisms is strongly affected by physical barriers and geographical distance, other highly mobile species are able to overcome such constraints. In southern South America, the Andes (here up to 6,900 m may constitute a formidable barrier to dispersal. In addition, this region was affected by cycles of intercalating arid/moist periods during the Upper/Late Pleistocene and Holocene. These factors may have been crucial in driving the phylogeographic structure of the vertebrate fauna of the region. Here we test these hypotheses in the burrowing parrot Cyanoliseus patagonus (Aves, Psittaciformes across its wide distributional range in Chile and Argentina. Results Our data show a Chilean origin for this species, with a single migration event across the Andes during the Upper/Late Pleistocene, which gave rise to all extant Argentinean mitochondrial lineages. Analyses suggest a complex population structure for burrowing parrots in Argentina, which includes a hybrid zone that has remained stable for several thousand years. Within this zone, introgression by expanding haplotypes has resulted in the evolution of an intermediate phenotype. Multivariate regressions show that present day climatic variables have a strong influence on the distribution of genetic heterogeneity, accounting for almost half of the variation in the data. Conclusions Here we show how huge barriers like the Andes and the regional environmental conditions imposed constraints on the ability of a parrot species to colonise new habitats, affecting the way in which populations diverged and thus, genetic structure. When contact between divergent populations was re-established, a stable hybrid zone was formed, functioning as a channel for genetic exchange between populations.

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

    Science.gov (United States)

    Pritchard, M. E.; Simons, M.

    2004-02-01

    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); and a caldera (Cerro Blanco, also called Robledo) in northwest Argentina is subsiding. We explore the range of source depths and volumes allowed by our observations, using spherical, ellipsoidal and crack-like source geometries. We further examine the effects of local topography upon the deformation field and invert for a spherical point-source in both elastic half-space and layered-space crustal models. We use a global search algorithm, with gradient search methods used to further constrain best-fitting models. Inferred source depths are model-dependent, with differences in the assumed source geometry generating a larger range of accepted depths than variations in elastic structure. Source depths relative to sea level are: 8-18 km at Hualca Hualca; 12-25 km for Uturuncu; 5-13 km for Lazufre, and 5-10 km at Cerro Blanco. Deformation at all four volcanoes seems to be time-dependent, and only Uturuncu and Cerro Blanco were deforming during the entire time period of observation. Inflation at Hualca Hualca stopped in 1997, perhaps related to a large eruption of nearby Sabancaya volcano in May 1997, although there is no obvious relation between the rate of deformation and the eruptions of Sabancaya. We do not observe any deformation associated with eruptions of Lascar, Chile, at 16 other volcanoes that had recent small eruptions or fumarolic activity, or associated with a short-lived thermal anomaly at Chiliques volcano. We posit a hydrothermal system at Cerro Blanco to explain the

  2. Vernal Point and Seismic Activity in Tibet Mountains and Andes Mountains

    Science.gov (United States)

    Chavez-Sumarriva, Israel; Chavez-Campos, Teodosio; Chavez S, Nadia

    2014-05-01

    The gravitational influence of the sun and moon on the equatorial bulges of the mantle of the rotating earth causes the precession of the earth. The retrograde motion of the vernal point through the zodiacal band is 26,000 years and passes through each constellation in an average of 2000 years (Milankovitch subcycle). The vernal point retrogrades one precessional degree approximately in 72 years (Gleissberg-cycle), and approximately enters into the Aquarius constellation (declination 11.5° S) on March 20, 1940. On earth this entry was verify through: a) stability of the magnetic equator in the south central zone of Peru and in the north zone of Bolivia (11.5º South latitude) since 1940 b) the greater intensity of equatorial electrojet (EEJ) in Peru and Bolivia since 1940. Besides, there was a long history of studies of coupling between earthquake-ionosphere. In IUGG (Italy-2007), Cusco was proposed as a prime meridian that was based on: (1) the new prime meridian (72º W == 0º) was parallel to the Andes and its projection the meridian (108° E == 180º) intersects the Tibetan plate (Asia). (2) On earth these two areas present the greatest thickness of the crust with an average depth of 70 kilometers. The aim was to synchronize the earth sciences phenomena (e.g. geology, geophysics, etc.). The coordinate system had the vernal point from meridian (72º W== 0º) and March 20, 1940. The retrograde movement of the vernal point was the first precessional degree (2012 = 1940 + 72). The west coast of South America (parallel to meridian 72º W== 0º) was a segment of the circum-pacific seismic belt where more than two thirds of major earthquakes in the world happened. During the first precessional degree (1940 +72 ==2012) seismic activity were: (a) near the new prime meridian (72° W == 0°) occurs in: (a1) Haiti (18.4° N, 72.5° W), January 12, 2010 with magnitude of 7.0 Mw. (a2) Chile (36.28° S, 73.23° W), February 27, 2010 with Magnitude of 8.8 Mw. (a3) Chile (35

  3. Assessment of Paleozoic terrane accretion along the southern central Andes using detrital zircon geochronology

    Science.gov (United States)

    McKenzie, R.; Horton, B. K.; Fuentes, F.; Fosdick, J. C.; Capaldi, T.; Stockli, D. F.; Alvarado, P. M.

    2015-12-01

    Two distinct Paleozoic terranes known as Cuyania and Chilenia occupy the southern central Andes of Argentina and Chile. Because the proposed terrane boundaries coincide with major structural elements of the modern Andean system at 30-36°S, it is important to understand their origins and potential role in guiding later Andean deformation. The Cuyania terrane of western Argentina encompasses the Precordillera (PC) and a thick-skinned thrust block of the western Sierras Pampeanas, persisting southward to the San Rafael Basin (SRB). Although recently challenged, Cuyania has been long considered a piece of southern Laurentia that rifted away during the early Cambrian and collided with the Argentine margin during the Ordovician. Chilenia is situated west of Cuyania and includes the Frontal Cordillera (FC) and Andean magmatic arc. This less-studied terrane was potentially accreted during an enigmatic Devonian orogenic event. We present new detrital zircon U-Pb age data from siliciclastic sedimentary rocks that span the entire Paleozoic to Triassic from the FC, PC, and SRB. Cambrian rocks of the PC exhibit similar zircon age distributions with prominent ~1.4 and subordinate ~1.1 Ga populations, which are distinct from other Paleozoic strata. Plutonic rocks with these ages are common in southern Laurentia, whereas ~1.4 Ga zircons are uncommon in South American age distributions. This supports a Laurentian origin for Cuyania in isolation from Argentina during the Cambrian. Upper Paleozoic strata from the PC, FC, and SRB all yield similar age data suggesting shared provenance across the proposed Cuyania-Chilenia suture. Age distributions also notably lack Devonian-age grains. The regional paucity of Devonian plutonic rocks and detrital zircon casts doubt on a possible arc system between these terranes at this time, a key requisite for the mid-Paleozoic transfer and accretion of Chilenia to the Argentine margin. Collectively, these data question the precise boundaries of the

  4. Multi-sensor geophysical constraints on crustal melt in the central Andes: the PLUTONS project

    Science.gov (United States)

    Pritchard, M. E.; Comeau, M. J.; West, M. E.; Christensen, D. H.; Mcfarlin, H. L.; Farrell, A. K.; Del Potro, R.; Gottsmann, J.; McNutt, S. R.; Michelfelder, G.; Diez, M.; Elliott, J.; Henderson, S. T.; Keyson, L.; Delgado, F.; Unsworth, M. J.

    2015-12-01

    The central Andes is a key global location to quantify storage, transport, and volumes of magma in the Earth's crust as it is home to the world's largest zone of partial melt (the Altiplano-Puna Magma or Mush Body, APMB) as well as the more recently documented Southern Puna Magma Body (SPMB). We describe results from the recently completed international PLUTONS project that focused inter-disciplinary study on two sites of large-scale surface uplift that presumably represent ongoing magmatic intrusions in the mid to upper crust - Uturuncu, Bolivia (in the center of the APMB) and Lazufre on the Chile-Argentina border (on the edge of the SPMB). In particular, a suite of geophysical techniques (seismology, gravity, surface deformation, and electro-magnetic methods) have been used to infer the current subsurface distribution and quantity of partial melts in combination with geochemical and lab studies on samples from the area. Both Uturuncu and Lazufre show separate geophysical anomalies in the upper and mid/lower crust (e.g., low seismic velocity, low resistivity, etc.) indicating multiple distinct reservoirs of magma and/or hydrothermal fluids with different properties. The characteristics of the geophysical anomalies differ somewhat depending on the technique used - reflecting the different sensitivity of each method to subsurface melt of different compositions, connectivity, and volatile content. For example, the depth to the top of the APMB is shallower in a joint ambient noise tomography and receiver function analysis compared to a 3D magnetotelluric inversion. One possibility is that the seismic methods are detecting brines above the APMB that do not have a large electromagnetic signature. Comparison of the geophysical measurements with laboratory experiments at the APMB indicate a minimum of 4-25% melt averaged over the region is needed -- higher melt volumes are permitted by the gravity and MT data and may exist in small regions. However, bulk melt values above

  5. Water Scarcity and the Impact of the Mining and Agricultural Sectors in Chile

    OpenAIRE

    Douglas Aitken; Diego Rivera; Alex Godoy-Faúndez; Eduardo Holzapfel

    2016-01-01

    Chile contains some of the driest areas in the world, yet human activities in these areas require large volumes of water, the result is regions experiencing high water scarcity leading to environmental degradation, conflicts and reduced industrial productivity. The aim of this paper was to quantify the water scarcity in the central and northern regions by calculating the water scarcity index—the ratio of annual water demand to availability. A focus of the paper was to determine the impact of ...

  6. Local livelihoods, conservation and mining: An uneven struggle over land access in Punta de Choros, Chile

    OpenAIRE

    Lenninger, Paula

    2015-01-01

    The purpose of this thesis is to explore the relation between national economic ventures, environmental security and community development. It does so through a case study of the implementation process of an iron and copper mine (La Dominga Project) in a “biodiversity hotspot” in central-northern Chile. Using qualitative methods to gather empirical data and a discursive analytical framework, it seeks to understand how the mine affects livelihoods and community development, as perceived by loc...

  7. Rocky Intertidal Zonation Pattern in Antofagasta, Chile: Invasive Species and Shellfish Gathering

    OpenAIRE

    Juan Carlos Castilla; Manríquez, Patricio H.; Alejandro Delgado; Verónica Ortiz; María Elisa Jara; Manuel Varas

    2014-01-01

    BACKGROUND: Biological invasions affecting rocky intertidal zonation patterns, yield information on species interactions. In the Bay of Antofagasta, northern Chile, the non-indigenous tunicate Pyura praeputialis, originally from Australia, has invaded (in the past century or so) and monopolized a major portion of the mid-intertidal rocky shore, displacing upshore the native mussel Perumytilus purpuratus. In Antofagasta the tunicate is subjected to intensive exploitation. Monitoring protocols ...

  8. Diversity of Quinoa in a Biogeographical Island: a Review of Constraints and Potential from Arid to Temperate Regions of Chile

    Directory of Open Access Journals (Sweden)

    Didier BAZILE

    2014-12-01

    Full Text Available Chile, isolated by a hyper-arid desert in the north, the Andes Range to the east and the Pacific and Antarctic waters (west and south, has a highly endemic flora. This hotspot of biodiversity is in danger not only due to increasing desertification, but also because human activities can diminish agrobiodiversity. Quinoa (Chenopodium quinoa Willd. is an Andean species producing highly nutritious grains, which almost disappeared from Chile during the Spanish colonization. Today less than 300 small-scale and highly isolated farmers still grow it as a rain-fed crop. This review describes the biogeographical-social context of quinoa in Chile, and its high genetic diversity as a product of a long domestication process, resulting in numerous local landraces whose conservation and use for breeding improved varieties is of paramount importance. We suggest the term “lighthouse crop” to emphasize its contribution to small scale ecological and bio diverse agriculture, particularly in stressful environments, to promote a healthier nutrition and more equitable markets in the world. Furthermore this crop and its exceptional nutritional properties were invoked by the United Nations Food and Agriculture Organization (FAO to promote its use worldwide, and to declare 2013 the International Year of Quinoa.

  9. Cobre labrado, alambique y aguardiente. Chile y Argentina, 1586-1850

    Directory of Open Access Journals (Sweden)

    Pablo Lacoste

    2016-01-01

    Full Text Available El estudio examina el desarrollo de la producción, transporte y distribu- ción de cobres labrados y alambiques para elaborar aguardiente en Chile y el oeste de la actual Argentina, desde el primer alambique registrado (1586 hasta mediados del siglo XIX. Se detecta que el principal polo de manufactura de estos artefactos se encontraba en el Norte Chico de Chile, entre Huasco y La Serena. Desde allí, el uso de los alambiques se difundió por un amplio espacio. La ruta del alambique y el cobre labrado se extendió por 5.000 kilómetros, llegando a Guayaquil, Trujillo, Callao, Cinti, Jujuy y Salta por el norte; y a Valdivia y Chiloé por el sur, a ambos lados de la cordillera de los Andes. Floreció así un intenso proceso de integración socioeconómica regional, a la vez que se fortaleció el desa- rrollo agroindustrial con la posibilidad de destilar aguardientes. De esta manera se sentaron las bases para el surgimiento de varios productos típicos.

  10. A Climatology of Ripple Instabilities in the OH Airglow at Cerro Pachon, Chile

    Science.gov (United States)

    Gelinas, L. J.; Hecht, J. H.; Walterscheid, R. L.; Rudy, R. J.

    2015-12-01

    Airglow imaging provides a unique means by which to study many wave-related phenomena in the 80 to 100 km altitude regime. Observations reveal quasi-monochromatic disturbances associated with atmospheric gravity waves (AGWs) as well as small-scale instabilities often called ripples. Ripples are wavelike features that resemble AGWs in appearance, but have short horizontal wavelengths (Corporation's Nightglow Imager (ANI) is located at the Andes Lidar Observatory near the crest of Cerro Pachon, Chile. ANI observes nighttime OH emission (near 1.6 microns) every 2 seconds over an approximate 73 degree field of view, which allows the study of AGW and ripple features over very short temporal and spatial scales. An automated wave detection algorithm is used to identify ripple and quasi monochromatic wave features in the ANI data. Ripples are characterized by their wavelength, orientation, drift speed and location in the image. Quasi-monochromatic waves are quantified by wavelength, wave period and propagation direction. We present a climatology of ripple instabilities at Chile, including comparisons to the background quasi-monochromatic wave field. Lidar and radar data are used to determine the background wind and temperatures, which allows comparisons between ripple observations and evanescent regions and potentially unstable regions identified by Richardson number.

  11. Primer registro en Chile de Antarctophthirus microchir (Anoplura en lobo marino común (Otaria flavescens First record of Antarctophthirus microchir (Anoplura in the southern sea lion (Otaria flavescens in Chile

    Directory of Open Access Journals (Sweden)

    A Crovetto

    2008-01-01

    Full Text Available Los ectoparásitos de los mamíferos marinos en Chile son poco conocidos. Se recolectaron individuos en animales adultos y jóvenes de una lobería reproductiva de lobo marino común (Otaria flavescens en Isla Metalqui, de la Región de Los Lagos, Chile. Se identifican y describen los especímenes de Anoplura apoyado en claves existentes. Dicha descripción y la comparación con la evolución y distribución de la familia Otariidae en el mundo nos permite concluir que Antarctophthirus microchir es una especie descrita por primera vez en Chile y podría representar una posible evidencia de un origen monofilético de los grupos de Otariidae en los hemisferios norte y sur.The ectoparasitic fauna associated to marine mammals is scarcely known in Chile. This report deals with a sample of Anoplura parasites collected from adult and juvenile Otaria flavescens, the southern sea lion, at the Los Lagos Region, Chile. The Anoplura were taxonomically determined using the existent keys and they were subsequently described. This is the first record of Antarctophthirus microchir in Chile which, together with what is already known about the geographical distribution and the world evolutionary history of the Otariidae, could represent another evidence of the monophyly of the northern and southern hemisphere Otariidae groups.

  12. Lateglacial temperature reconstruction in the Eastern Tropical Andes (Bolivia) inferred from paleoglaciers and paleolakes

    Science.gov (United States)

    Martin, L.; Blard, P. H.; Lave, J.; Prémaillon, M.; Jomelli, V.; Brunstein, D.; Lupker, M.; Charreau, J.; Mariotti, V.; Condom, T.; Bourles, D. L.

    2015-12-01

    Recent insights shed light on the global mechanisms involved in the abrupt oscillations of the Earth climate for the Late Glacial Maximum (LGM) to Holocene period (Zhang et al., 2014; Banderas et al., 2015). Yet the concomitant patterns of regional climate reorganization on continental areas are for now poorly documented. Particularly, few attempts have been made to propose temporal reconstructions of the regional climate variables in the High Tropical Andes, a region under the direct influence of the upper part of the troposphere. We present new glacial chronologies from the Zongo (16.3°S - 68.1°W, Bolivia) and Wara-Wara (17.3°S - 66.1°W, Bolivia) valleys based on Cosmic Ray Exposure dating (CRE) from an exceptional suite of recessive moraines. These new data permitted to refine existing chronologies (Smith et al., 2005 ; Zech et al., 2010): the Zongo valley is characterized by an older local last glacial maximum than the Wara Wara valley. Both site