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Sample records for andean cordillera central

  1. Petrographic and Geochemical Characterization of the Cambumbia STOCK in Andean Central Cordillera, Colombia

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    Rojas Lequerica, S.; Jaramillo Mejía, J.; Concha Perdomo, A.

    2012-12-01

    The Cambumbia Stock is located on the western flank of the Central Cordillera of the northern Andes. The goals of this study were to petrographic and geochemically characterize the Cambumbia igneous body and to establish its petrogenetic history. 41 samples were collected, 28 for petrographic analysis and 14 for elementary chemical determination by ICP-MS. Petrographically the samples were classified as hornblende and pyroxene-gabbros varying to diorites, gabbronorites and tonalites, the rock texture varies from medium to coarse granular grain, with local microporfiritic texture. It was concluded from the major elements analysis that the samples correspond to the sub-alkaline series with low K content, mainly in the calc-alkaline series, within the gabbros and diorites fields. By using the SiO2 vs TiO2 (Jaramillo, 1980), Th/Yb vs Ta/Yb (Pearce, 1984) (Fig. 1) and Zr/117-Th-Nb/16 (Wood, 1979) diagrams it was determined that these rocks were generated in two geotectonic environments: one type MOR (extension) and other island arc (subduction, compression). Petrographic and geochemical comparisons between the rocks of Cambumbia Stock and Diorite and Gabbro El Pueblito (Giraldo, 2009) (located about 25 km to the north-west) may postulate a possible genetic link between them. 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 (Middle Triassic). This age is consistent with the global event of the extension and fragmentation of Pangea supercontinent. In addition, the mantle nature of the source and the petrogenetic evolution of the magmatic system were established. References GIRALDO, M.I., (2009): Esquema geodinámica de la parte noroccidental de la cordillera Central de Colombia. (Thesis). p.56-68. Universidad Nacional de Colombia, Medellín. JARAMILLO, J.M. (1980): Petrology and geochemistry of the Nevado del Ruiz Volcano northern Andes, Colombia (Thesis). 167 p. University of Houston

  2. 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

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    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.

  3. DISTRIBUCIÓN DEL AGUA LLUVIA EN TRES BOSQUES ALTOANDINOS DE LA CORDILLERA CENTRAL DE ANTIOQUIA, COLOMBIA RAINFALL DISTRIBUTION IN THREE HIGH ANDEAN FORESTS IN THE CENTRAL CORDILLERA OF COLOMBIA

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    Juan Diego León Peláez

    2010-06-01

    Full Text Available Se estudió la distribución del agua lluvia durante tres años en un bosque climácico de roble (Quercus humboldtii y dos plantaciones forestales, de pino (Pinus patula y ciprés (Cupressus lusitanica ubicados en los Andes colombianos. Los principales ingresos de agua al bosque ocurrieron por la lluvia, cuyo valor medio anual fue 1.700 mm año-1. La precipitación interna tuvo la mayor participación de los flujos hídricos del bosque, siendo máxima en el cipresal (1.486 mm a-1, 90 % y mínima en el pinar (1.389 mm a-1, 81 %, mientras que el escurrimiento cortical fue muy bajo en los tres bosques (1-3 mm a-1, 0,1-0,2 %. La máxima intercepción se presentó en el pinar (329 mm a-1, equivalente al 19 % de la lluvia. A diferencia de estos flujos hídricos del dosel los flujos hídricos del suelo sí mostraron diferencias significativas entre coberturas (P Rainfall distribution was assessed for three years in a mature oak forest (Quercus humboldtii, pine (Pinus patula and cypress (Cupressus lusitanica plantations in the northern part of the colombian Andean mountains. An annual average of 1700 mm was the main water input in the forests, which came from the bulk precipitation. The higher water flows were represented by throughfall, which showed a maximum value in the cypress (1486 mm y¹, 90% and a minimum one in the pine (1389 mm y¹, 81% plantations, respectively. Stemflow was very low in the three forest types (1-3 mm y¹, 0.1-0.2%. The maximum amount of water intercepted by forest crowns was found in the pine plantation (329 mm y¹, which accounted for 19% out of the total rainfall. In opposition to the patterns found for throughfall and stemflow, soil hydric flows did show significant differences among forest types (P<0.05. In the oak forest water infiltration inversely decreased with soil depth; this forest type showed the lowest water losses by deep drainage (2 mm y¹. Finally, throughfall and stemflow were significantly correlated with the

  4. The Cordillera Blanca normal fault and its contribution to the Andean topographic evolution (northern Peru)

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    Margirier, Audrey; Robert, Xavier; Schwartz, Stéphane; Audin, Laurence

    2015-04-01

    Nature and localization of Quaternary tectonics remains largely unconstrained in Peruvian Andes as well as the mechanism driving rock uplift. The Cordillera Blanca normal fault accommodates extension in a convergent context. The fault system trends parallel to the subduction zone, just above the Peruvian flat-slab, and separate the Cordilleras Blanca and Negra. The Cordillera Blanca batholith (8-5 Ma) is an elongated pluton, emplaced at ~6 km depth in the Jurassic sedimentary country rocks. The Cordillera Blanca range (6768 m) that comprises the highest Peruvian peak built the footwall of the fault. The ~200 km-long fault has showed ~4500 m of vertical displacement since 5 Ma. This normal fault is described as active despite the lack of historical seismicity and constitutes a striking singularity within the prevailing compressional setting of the Andean orogeny. This region is a perfect target to explore the contribution of large normal fault in relief building. Our goals are to determine if the fault was pre-existing before the Cordillera Blanca batholith emplacement, when it has been reactivated and how does it interact with the batholith exhumation. For that purpose, we focus on brittle deformation analysis from a regional scale (faults trends) to outcrop scale (fault planes, striaes and kinematics). We present here new structural data and focal mechanisms indicating a senestral transtensive component on the Cordillera Blanca normal fault and a regional extensional regime in the Cordillera Negra area. We compare the paleotensors obtained from the inversion of the microstructural data and focal mechanisms with the exhumation history deduced from the thermochronological data to constrain the role of the normal fault in relation with relief building. We propose that the Cordillera Blanca normal fault is an inherited tectonic feature reactivated in transtension after the slab flattening at ~8 Ma. The differential exhumation of the Cordillera Blanca with respect to

  5. Central Andean crustal structure from receiver function analysis

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    Ryan, Jamie; Beck, Susan; Zandt, George; Wagner, Lara; Minaya, Estela; Tavera, Hernado

    2016-07-01

    The Central Andean Plateau (15°-27°S) is a high plateau in excess of 3 km elevation, associated with thickened crust along the western edge of the South America plate, in the convergent margin between the subducting Nazca plate and the Brazilian craton. We have calculated receiver functions using seismic data from a recent portable deployment of broadband seismometers in the Bolivian orocline (12°-21°S) region and combined them with waveforms from 38 other stations in the region to investigate crustal thickness and crust and mantle structures. Results from the receiver functions provide a more detailed map of crustal thickness than previously existed, and highlight mid-crustal features that match well with prior studies. The active volcanic arc and Altiplano have thick crust with Moho depths increasing from the central Altiplano (65 km) to the northern Altiplano (75 km). The Eastern Cordillera shows large along strike variations in crustal thickness. Along a densely sampled SW-NE profile through the Bolivian orocline there is a small region of thin crust beneath the high peaks of the Cordillera Real where the average elevations are near 4 km, and the Moho depth varies from 55 to 60 km, implying the crust is undercompensated by ~ 5 km. In comparison, a broader region of high elevations in the Eastern Cordillera to the southeast near ~ 20°S has a deeper Moho at ~ 65-70 km and appears close to isostatic equilibrium at the Moho. Assuming the modern-day pattern of high precipitation on the flanks of the Andean plateau has existed since the late Miocene, we suggest that climate induced exhumation can explain some of the variations in present day crustal structure across the Bolivian orocline. We also suggest that south of the orocline at ~ 20°S, the thicker and isostatically compensated crust is due to the absence of erosional exhumation and the occurrence of lithospheric delamination.

  6. 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

  7. Recent (0-8 Ma) tectonics and exhumation processes in Cordilleras Blanca and Negra, Central Peru: Constraints from (U-Th)/He dating

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    Margirier, Audrey; Robert, Xavier; Gautheron, Cécile; Audin, Laurence

    2014-05-01

    The Central Andes are a classical example of topography building in front of an oceanic subduction. However, many first order questions are still debated: How do subduction processes and observed tectonic uplift interact along the Andean margin? What is the impact of tectonic, magmatism and climate on exhumation? The Cordilleras Blanca (6768 m) and Negra (5181 m), in north Central Peru, belong to the highest Andean reliefs. Both ranges trend parallel to the subduction zone and are separated by the NW-SE Rio Santa valley. The Cordillera Blanca pluton formed in an active subduction context at 8-5 Ma and renders an abnormal magmatic activity over a planar subduction. In contrast with the Cordillera Blanca, the Cordillera Negra is an older relief, which evolution and exhumation history has never been studied. A remarkable ~200 km-long normal fault system showing ~4500 m of vertical displacement since 5 Ma edges the western flank of the Cordillera Blanca. This region is a perfect target to study the impact of magmatism and subduction processes on exhumation. We perform a morphotectonic study on both cordilleras coupled with low-temperature thermochronology apatite (U-Th)/He dating to quantify these processes. Geomorphic parameters and altitude contrasts between these two ranges indicate a differential uplift. The Cordillera Negra displays a smooth and asymmetric relief from the West to the East whereas the Cordillera Blanca shows higher and sharper relief with North/South and East/West contrasts. We obtain apatite (U-Th)/He ages for twenty samples located along vertical and horizontal profiles at different latitudes of the Cordilleras Blanca and Negra. The (U-Th)/He ages range from 13.4 ± 1.3 to 5.6 ± 0.6 Ma in the Cordillera Negra and range from 11.8 ± 1.2 to 2.0 ± 0.2 Ma in the Cordillera Blanca. We use them as inputs in QTQt tools for time-temperature reconstructions and thus to constrain the exhumation history. Whole ages evidence a more regional exhumation than

  8. La cordillera oriental colombiana no se desprende de la cordillera central

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    Ujueta, Guillermo

    2012-01-01

    Geologically the Central and Eastern Cordilleras depict different periods of genesis and different types of rocks which allow them to keep their identities and independence from Colombia to Bolivia; however, in the area of study are connected by a bridge formed by a recent geomorphollogical feature which is the result of combined tectonic and volcanic stresses which took place toward the end of the Pliocene. This bridge has a direction NW-SE and connects the Cutanga Volcanoe on the Central Co...

  9. Tectonomagmatic Associations on the Central Andean Plateau

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    de Silva, S. L.; Viramonte, J. G.

    2012-12-01

    The Neogene evolution of the Central Andes is characterized by a strong association between plate convergence, mountain building and plateau formation, and magmatism. Plateau uplift by crustal shortening and thickening in the lower crust is broadly coincident with large scale silicic magmatism defined by the Neogene Central Andean ignimbrite province. Of particular interest here are the spatiotemporal correlations between silicic magmatism and tectonic evolution of the Altiplano-Puna plateau. Although magmatism is driven by the subduction-related flux from mantle to crust, the shift to "crustal" magmatism as indicated by elevated crustal isotopic indices after ~10Ma suggests a link between crustal thickening, plateau formation and silicic magmatism. In particular, elevated geotherms associated with crustal thickening and enhanced mantle flux associated with lithospheric delamination may have played a role in thermally preparing the Central Andean crust for enhanced silicic magma production during the extensive Neogene ignimbrite flare-up. Emplacement of these magmas in the upper crust throughout the Neogene may have fuelled a period of significant interaction between magmatism and tectonism on the plateau. With particular reference to the 21° to 24°S segment of the Central Andes, spatial and structural coincidence of calderas of the Altiplano Puna Volcanic Complex with the NW-SE striking Calama-Olacapata-El Toro fault zone suggests significant tectonomagmatic interaction. Location of calderas suggest that these regional faults focused magma intrusion and storage, while spatially and temporally correlated eruption pulses connote a tectonic control. Indeed, current thermomechanical models of magma chamber development and eruption triggering promote a role for external triggering of "perched" upper crustal magma chambers. This might have been achieved by melt-enhanced deformation, or alternatively, significant uplift (~1km) associated with the development of large

  10. Structural inheritance and selective reactivation in the central Andes: Cenozoic deformation guided by pre-Andean structures in southern Peru

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    Perez, Nicholas D.; Horton, Brian K.; Carlotto, Victor

    2016-03-01

    Structural, stratigraphic, and geochronologic constraints from the Eastern Cordillera in the central Andean plateau of southern Peru (14-15°S) demonstrate the existence and position of major pre-Andean structures that controlled the accumulation of Triassic synrift fill and guided subsequent Cenozoic deformation. The timing of initial clastic deposition of the Triassic Mitu Group is here constrained to ~ 242-233 Ma on the basis of detrital and volcanic zircon U-Pb geochronology. Regionally distinct provenance variations, as provided by U-Pb age populations from localized synrift accumulations, demonstrate Triassic erosion of multiple diagnostic sources from diverse rift-flank uplifts. Stratigraphic correlations suggest synchronous initiation of extensional basins containing the Mitu Group, in contrast with previous interpretations of southward rift propagation. Triassic motion along the NE-dipping San Anton normal fault accommodated up to 7 km of throw and hanging-wall deposition of a synrift Mitu succession > 2.5 km thick. The contrasting orientation of a non-reactivated Triassic normal fault suggests selective inversion of individual structures in the Eastern Cordillera was dependent on fault dip and strike. Selective preservation of a ~ 4 km thick succession of Carboniferous-Permian strata in the down-dropped San Anton hanging wall, beneath the synrift Mitu Group, suggests large-scale erosional removal in the uplifted footwall. Field and map observations identify additional pre-Andean thrust faults and folds attributed to poorly understood Paleozoic orogenic events preserved in the San Anton hanging wall. Selective thrust reactivation of normal and reverse faults during later compression largely guided Cenozoic deformation in the Eastern Cordillera. The resulting structural compartmentalization and across-strike variations in kinematics and deformation style highlight the influence of inherited Paleozoic structures and Triassic normal faults on the long

  11. Geodynamic Drivers of Vertical Crustal Motion: Integrating Paleoaltimetry with Basin Development in the Central Andean Plateau of Southern Peru

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    Sundell, K. E., II; Saylor, J. E.; Lapen, T. J.; Villarreal, D. P.; Styron, R. H.; Horton, B. K.; Cardenas, J.

    2015-12-01

    Determining the spatial and temporal relationships between surface uplift, tectonic subsidence, and exhumation during periods of oblique crustal shortening is essential to discriminating geodynamic processes controlling formation of high topography in the central Andes. Although subsidence analysis is now a standard tool, paleoelevation estimation remains a challenging task, as estimates based on proxy data can be complicated by uncertainties in the relative controls of tectonics and climate. We therefore adopt an approach of combining established tools of subsidence analysis and detrital geochronology with emerging methods of volcanic glass paleoaltimetry, which enables us to explore a broad range of viable interpretations to understand the development of intermontane basins and their relationship to the development of the central Andean plateau. We investigated a suite of temporally overlapping and spatially separate Cenozoic basins spanning the east-west extent of the central Andean plateau in southern Peru. These basins contain an exceptional record of the vertical movements of this region. We calculate sediment accumulation and subsidence rates through decompaction of measured stratigraphic sections, and reconstruct past environmental conditions based on the stable isotopic composition of ancient waters preserved in hydrated volcanic glass. These data and published records of crustal shortening and exhumation show that although paleoaltimetry data in the study areas may be interpreted in various ways, they are best explained by multiple geodynamic processes driving (i) Eocene-early Miocene development of high topography in the Western Cordillera, then (ii) a pulsed middle Miocene-present building of the central Andean plateau from west to east, consistent with global climate changes as well as regional climate shifts driven by topographic development of the Andean orogen.

  12. Imaging variations in the central Andean mantle and the subducting Nazca slab with teleseismic tomography

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    Scire, Alissa

    The Nazca-South America convergent margin is marked by the presence of the Andean mountain belt, which stretches along the 8000-km long western margin of the South American plate. The subduction zone is characterized by significant along-strike changes in both upper plate structure and slab geometry that make it an ideal region to study the relationship between the subducting slab, the surrounding mantle, and the overriding plate. This dissertation summarizes the results of three finite frequency teleseismic tomography studies of the central Nazca-South America subduction zone which improve our understanding of how along-strike variations in the Andean mountain belt and the subducting Nazca plate interact with each other and with the surrounding mantle. This is accomplished by first focusing on two smaller adjacent regions of the central Andes to explore upper mantle variations and then by using a combined dataset, which covers a larger region, to image the deeply subducted Nazca slab to investigate the fate of the slab. The first study focuses on the central Andean upper mantle under the Altiplano-Puna Plateau where normally dipping subduction of the Nazca plate is occurring (18° to 28°S). The shallow mantle under the Eastern Cordillera is generally fast, consistent with either underthrusting of the Brazilian cratonic lithosphere from the east or a localized "curtain" of delaminating material. Additional evidence for delamination is seen in the form of high amplitude low velocities under the Puna Plateau, consistent with proposed asthenospheric influx following lithospheric removal. In the second study, we explore the transition between normal and flat subduction along the north edge of the Altiplano Plateau (8° to 21°S). We find that the Peruvian flat slab extends further inland along the projection of the Nazca Ridge than was previously proposed and that when re-steepening of the slab occurs, the slab dips very steeply (˜70°) down through the mantle

  13. U-Pb La-ICP-ms geochronology and regional correlation of middle Jurassic intrusive rocks from the Garzon Massif, Upper Magdalena Valley and central cordillera, southern Colombia

    International Nuclear Information System (INIS)

    New U-Pb zircon geochronology from four granitic units sampled along a southeast-northwest transect between the Garzon massif and the Serrania de las Minas (central cordillera), records a middle Jurassic magmatic activity with two different spatio-temporal domains at ca. 189 ma and 180-173 ma. Reconnaissance data suggest that the four granitoids are characterized by mineralogical and geochemical characteristics akin to a continental magmatic arc setting. The new results suggest that the southern Colombian continental margin includes remnants of tectonomagmatic elements formed by the subduction of the Farallon plate under the South American continental margin. This middle Jurassic arc magmatism is part of the broader Andean scale arc province, and is significant for understanding the tectonic and paleogeographic scenario that characterized the Mesozoic tectonic evolution of the northern Andes.

  14. 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

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    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

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

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    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. Cenozoic stratigraphic development in the north Chilean forearc: Implications for basin development and uplift history of the Central Andean margin

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    Hartley, Adrian J.; Evenstar, Laura

    2010-11-01

    with volcanic activity limited to the periodic eruption of extensive ignimbrite sheets. Alluvial fan, fluvial and lacustrine sedimentation dominated within the endorheic basins from ˜ 8 to 3 Ma. After development of a regional unconformity at 3 Ma a change to isolated evaporite sub-basins took place in the Central Depression with small lacustrine basins developed along the flank of the Western Cordillera. The scale and grain size recorded in the sedimentary systems indicates that a substantial source area was located in the present day area of the Western Cordillera by 30 Ma and that this has persisted to the present day. This area also shed material eastwards into the Altiplano. The presence of such a topographic feature by 30 Ma suggests that a significant proportion of Andean uplift had occurred prior to the Late Miocene. This important uplift phase should be incorporated into any model of Andean uplift. The evidence from the basin-fill succession suggests that sediments accumulated in a basin developed in front of a broad monocline between 38 and 19 Ma and that a transition to a thrust-bounded foreland style basin took place after the development of the unconformity at 19 Ma.

  17. The Under-side of the Andes: Using Receiver Functions to Map the North Central Andean Subsurface

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    Ryan, J. C.; Beck, S. L.; Zandt, G.; Wagner, L. S.; Minaya, E.; Tavera, H.

    2012-12-01

    The Central Andean Uplift and Geodynamics of High Topography (CAUGHT) project is an interdisciplinary project to investigate connections between lithospheric removal, crustal shortening and surface uplift in the northern Bolivia and southern Peru region of the South American Andean orogen. The central Andes are defined by six major tectonomorphic provinces; the forearc, the volcanically active Western Cordillera (WC, ~6 km elevation), the internally drained Altiplano (~4 km elevation), an inactive fold and thrust belt in the Eastern Cordillera (EC, ~6 km elevation), a lower elevation active fold and thrust belt in the Subandean (SA) zone and the Beni, a foreland basin. Forty seismic stations installed for the CAUGHT project were deployed between 13° and 18° S latitude, covering the transition zone where the Altiplano region pinches out in southern Peru, in an effort to better constrain the changing character of the crust and mantle lithosphere. Geologic studies across the northern Bolivian portion of the eastern Andean margin (15-17° S) have documented a total of 275 km of upper crustal shortening (McQuarrie et al, Tectonics, v27, 2008), which may be associated with crustal thickening and/or the removal of lithospheric material as a thickened lithosphere root becomes unstable. For this receiver function (converted wave) study, we have little coverage in the forearc and foreland, ~75 km spacing in most of the array, and a relatively dense ~20 km spaced profile along the Charaña-La Paz-Yucumo transect, the eastern portion of which is nearly coincident with the balanced cross-section of McQuarrie et al. (2008). Using the first year of available data, more than 1200 receiver functions have been calculated using an iterative deconvolution method, and stacked using the common conversion point (CCP) method, along profiles parallel to and nearly coincident to those used for the geologic shortening estimates. We identified arrivals for the Moho and generated a 3D map of

  18. Synopsis of Central Andean Orthalicoid land snails (Gastropoda, Stylommatophora), excluding Bulimulidae

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    Abraham S.H. Breure; Avila, Valentín Mogollón

    2016-01-01

    Abstract A faunal overview is presented of the molluscan families Amphibulimidae , Megaspiridae , Odontostomidae , Orthalicidae , Simpulopsidae in Bolivia, Ecuador, and Peru. These Central Andean countries are known for their biodiverse malacofauna, of which the superfamily Orthalicoidea takes relatively a large share. In this paper the five families containing 103 (sub)species, for which systematic information (original publication, type locality, type depository, summarizing literature) and...

  19. Geological and structural setting, age, and geochemistry of the orogenic gold deposits at the Pataz Province, Eastern Andean Cordillera, Peru

    OpenAIRE

    Haeberlin, Yves; Fontboté, Lluis; Moritz, Robert

    2004-01-01

    La province de Pataz au Nord-Pérou est la plus septentrionale des ceintures paléozoïques d'or, antimoine et tungstène orogéniques (mésothermales) de la Cordillère Orientale des Andes Centrales. Longue de plus de 160 km, elle est connue pour ses veines épigénétiques de quartz aurifères riches en sulfures (ressource: 40 millions d'onces d'or). Les minéralisations, datées à ~314 Ma, sont localisées dans des fractures inverse-décrochantes dextres et d'extension le long des marges et à l'intérieur...

  20. Geological and structural setting, age, and geochemistry of the orogenic gold deposits at the Pataz Province, Eastern Andean Cordillera, Peru

    OpenAIRE

    Haeberlin, Yves

    2001-01-01

    La province de Pataz au Nord-Pérou est la plus septentrionale des ceintures paléozoïques d'or, antimoine et tungstène orogéniques (mésothermales) de la Cordillère Orientale des Andes Centrales. Longue de plus de 160 km, elle est connue pour ses veines épigénétiques de quartz aurifères riches en sulfures (ressource: 40 millions d'onces d'or). Les minéralisations, datées à ~314 Ma, sont localisées dans des fractures inverse-décrochantes dextres et d'extension le long des marges et à l'intérieur...

  1. Geochronology, geochemistry and tectonic evolution of the Western and Central cordilleras of Colombia

    Science.gov (United States)

    Villagómez, Diego; Spikings, Richard; Magna, Tomas; Kammer, Andreas; Winkler, Wilfried; Beltrán, Alejandro

    2011-08-01

    Autochthonous rocks of the pre-Cretaceous continental margin of NW South America (the Tahami Terrane) are juxtaposed against a series of para-autochthonous rock units that assembled during the Early Cretaceous. Allochthonous, oceanic crust of the Caribbean Large Igneous Province collided with and accreted onto the margin during the Late Cretaceous. We present the first regional-scale dataset of zircon U-Pb LA-ICP-MS ages for intrusive and metamorphic rocks of the autochthonous Tahami Terrane, Early Cretaceous igneous para-autochthonous rocks and accreted oceanic crust. The U-Pb zircon data are complemented by multiphase 40Ar/ 39Ar crystallization and cooling ages. The geochronological data are combined with whole rock major oxide, trace element and REE data acquired from the same units to constrain the tectonic origin of the rock units and terranes exposed in the Western Cordillera, Cauca-Patía Valley and the Central Cordillera of Colombia. The Tahami Terrane includes lower Paleozoic orthogneisses (~ 440 Ma) that may have erupted during the active margin stage of the Rheic Ocean. Basement gneisses were intruded by Permian, continental arc granites during the final assembly of Pangea. Triassic sedimentary rocks were subsequently deposited in rift basins and partially melted during high-T metamorphism associated with rifting of western Pangea during 240-220 Ma. Continental arc magmatism during 180-145 Ma is preserved along the whole length of the Central Cordillera and was followed by an Early Cretaceous out-board step of the arc axis and the inception of the Quebradagrande Arc that fringed the continental margin. Back-stepping of the arc axis may have been caused by the collision of buoyant seamounts, which were coeval with plateau rocks exposed in the Nicoya Peninsular of Costa Rica. Rapid westward drift of South America closed the Quebradagrande basin in the late Aptian and caused medium-high P-T metamorphic rocks of the Arquía Complex to exhume and obduct onto

  2. Three new species of Pristimantis (Lissamphibia, Anura from montane forests of the Cordillera Yanachaga in Central Peru

    Directory of Open Access Journals (Sweden)

    William E. Duellman

    2007-12-01

    Full Text Available We describe three additional new species of Pristimantis from the Cordillera Yanachaga, a part of the Andes in central Peru. Analyses of DNA sequences of the mitochondrial rRNA genes show that onespecies is a close relative of P. bipunctatus (P. conspicillatus Group, another is a close relative of P. stictogaster (P. peruvianus Group, and the third is related to several species in the P. unistrigatus Group. The first two species are morphologically similar to their closest relatives but occur at lower elevations. Twenty-nine species of Pristimantis and Phrynopus are known from the vicinity of the Cordillera Yanachaga. The number of species, especially of Pristimantis, is high in the humid montane forestin comparison with other sites in humid montane forests in Peru, but the number is lower than on the western slopes of the Andes in Ecuador.

  3. Three-dimensional inversion of magnetotelluric data from the Central Andean continental margin

    Science.gov (United States)

    Kühn, Christine; Küster, Jonas; Brasse, Heinrich

    2014-12-01

    Magnetotelluric data were collected in the late 1990s in the Central Andes of Chile and Bolivia, with the aim to delineate the electrical conductivity distribution in the subsurface and its relations to subduction processes. In previous studies, these data were interpreted based on 2-D models. The principal result was a vast conductivity zone beneath the Altiplano high plateau at mid and lower crustal depths and a much smaller, though significant conductor associated with the Precordillera Fault System. However, there are some significant 3-D effects in the investigation area, in particular near the coast and on the eastern Altiplano. The aim of this work is to give a reinterpretation based on new 3-D inversion of these data. The 3-D inversion not only provides a better fit to the data compared to 2-D results but furthermore allows to include sites with strong telluric distortion which were ignored in previous studies. We are now able to explain anomalous phases above 90° and induction arrows pointing subparallel to the coast as observed at several sites in the Coastal Cordillera. These strongly distorted data are caused by highly conductive near-surface structures that are partly connected to the Pacific Ocean, forcing currents to flow around the sites. The lower crust beneath the Coastal Cordillera resembles a poorly conductive, nearly homogeneous half-space and is electrically unremarkable. Besides, we can now image the Precordillera conductor as a continuous, elongated feature. The volcanic arc of the Western Cordillera is highly resistive with the exception of a few conductive spots which may be associated with certain individual volcanoes or geothermal resources, respectively. The Altiplano conductor is again the dominant electrical feature in the Central Andes, indicating widespread melting of the middle and lower back-arc crust.

  4. Shortening Record in the Central Andean Plateau of Southern Peru: Basement Inversion, Thin-skinned Thrusting, and Geomorphic Response

    Science.gov (United States)

    Perez, N.; Horton, B. K.; McQuarrie, N.; Stübner, K.; Ehlers, T. A.

    2015-12-01

    Variations in the inherited structural architecture along western South America influence the timing, magnitude, and style of Andean deformation and topographic evolution. New results from mapping, balanced cross-section construction, apatite and zircon (U-Th)/He thermochronology, and geomorphology spanning the Altiplano, Eastern Cordillera and Subandean zone of southern Peru define the role of Triassic rift inversion on Cenozoic deformation style, thrust belt kinematics, exhumation timing, and spatial variation of canyon incision. A minimum of 130 km (38%) shortening along a 200 km transect accommodated by thin- and thick-skinned structures involved selective reactivation of Triassic normal faults that fed slip to shallower detachments of thin-skinned fold-thrust systems. Map relationships define unique structural domains defined by inherited normal faults. In the Eastern Cordillera, new zircon (U-Th)/He results from a Triassic pluton reveal Oligocene-Miocene (~26-18 Ma) cooling, consistent with previously reported exhumation from ~40 km along strike to the NW. However, rapid ~15 Ma cooling revealed by new apatite (U-Th)/He data is ~11 Myr older than equivalent rocks in a similar structural setting ~40 km to the NW. This suggests a potential middle Miocene shift from synchronous to diachronous exhumation along strike. Modern fluvial profiles constructed along the Eastern Cordillera show a reduction in knickpoint elevations from SE to NW, suggesting more youthful uplift toward the NW, comparable to the spatial trend in apatite (U-Th)/He ages. The deformation front reached the Subandean zone by ~15 Ma, after the majority of reported deformation in the Eastern Cordillera and Altiplano. These variations in exhumation over such distances are consistent with multiple potential scenarios: a northward propagating wave of uplift, spatial variations in climatically driven incision, interactions with mantle dynamics, or complex structural geometries.

  5. Kinematic evolution of Andean fold-thrust structures along the boundary between the Eastern Cordillera and Middle Magdalena Valley basin, Colombia

    Science.gov (United States)

    SáNchez, Javier; Horton, Brian K.; Tesón, Eliseo; Mora, AndréS.; Ketcham, Richard A.; Stockli, Daniel F.

    2012-06-01

    Surface and subsurface data support a kinematic reconstruction of Cenozoic fold-thrust deformation along the Eastern Cordillera-Magdalena Valley transition in Colombia. The La Salina fault (LSF) marks the boundary between west-vergent Eastern Cordillera structures and hinterland deposits of the Middle Magdalena Valley basin. Apatite fission track and (U-Th)/He thermochronological results for the west-directed LSF reveal initial hanging wall exhumation during middle Eocene-early Oligocene (45-30 Ma) shortening, renewed exhumation in the early middle Miocene (18-12 Ma), and accelerated late Miocene-Pliocene (12-3 Ma) exhumation. Vitrinite reflectance data suggest maximum burial of 4-6 km, helping constrain Cenozoic basin architecture. Mapping of the LSF reveals hanging wall Cretaceous-Eocene rocks in a broad anticline-syncline pair with limited faulting and footwall Eocene-Quaternary basin fill in a complex series of tight thrust-related folds. Limited displacement along the westernmost (frontal) thrust suggests that shortening is largely accommodated by east-directed thrusting within a broader triangle zone of a passive-roof duplex (and probable minor strike-slip deformation). In the preferred kinematic restoration, the most recent phase of shortening to transpressional deformation represents out-of-sequence reactivation of the LSF consistent with irregular crosscutting relationships among footwall structures. Earliest exhumation by 45-30 Ma in the Eastern Cordillera fold-thrust belt is correlated with increased sedimentary lithic fragments and high compositional maturity in sandstones of the adjacent Magdalena Valley basin. Exhumation since ˜15 Ma coincided with decreased compositional maturity and elevated accumulation rates for the Real Group. The compositional provenance shifts are attributed to westward advance of fold-thrust deformation into the proximal (eastern) segments of the Magdalena Valley basin.

  6. Petrological characteristics of Plio-Quaternary 'Sencca' Ignimbrites, Western Cordillera of the Central Andes in Peru

    Science.gov (United States)

    Çubukçu, H. E.; Gerbe, M.-C.; Thouret, J.-C.; de la Rupelle, A.; Boivin, P.

    2012-04-01

    Large-volume ignimbrite deposits have been emplaced between 24.6 and 1.37 Ma in the western Andean Cordillera of Southern Peru. The ignimbrites older than 9 Ma (Nazca, Alpabamba, Huaylillas and Caraveli ignimbrites) have formed plateaus, whereas the deep valleys incised in plateaus have been filled by younger Lower-Upper Sencca (~5- 2 Ma) and Las Lomas ignimbrites. Among the younger valley-filling units, Lower and Upper Sencca ignimbrites, with intercalated Upper Barroso lavas, have probably originated from a source beneath the Nevado Coropuna volcano. The unwelded-to-loose, crystal-poor pumice flows of Las Lomas unit (c.1.56-1.37 Ma) can be readily distinguished in the field from the rhyolitic Sencca ignimbrites. In contrast, discriminating Lower Sencca from Upper Sencca deposits in the field is difficult due to comparable lithofacies characteristics. Such a distinction is, however, essential in order to determine temporal constraints on valley incision. The Lower Sencca compound ignimbrite sheet is more widespread (~800 km2) than the Upper Sencca ignimbrite sheet (~600 km2). The Lower Sencca ignimbrites usually form terraces hanging on valley sides but Upper Sencca form deposits crop out near the present valley bottoms or in shallow valleys on high plateaus around Barroso volcanoes. The Lower Sencca ignimbrite is composed of multiple cooling units with a crystal- and fiamme-rich vitrophyric base, overlain by strongly welded, eutaxitic subunits towards the top. Uppermost subunits exhibit an indurated ash and pumice rich vapour-phase facies. The Upper Sencca ignimbrite sheet comprises two subunits only: (1) the basal, black vitrophyre, overlain by a fiamme- and crystal-rich, strongly welded, eutaxitic subunit; 2) the upper subunit with an indurated or slightly welded, crystal-poor, pumice-rich vapour phase facies The dominant mineralogy of Lower Sencca compound ignimbrites includes plagioclase (An13-68) + alkali feldspar (Or38-65) + biotite (XMg: Mg/Mg+Fe= 0

  7. Size class structure, growth rates, and orientation of the central Andean cushion Azorella compacta

    Science.gov (United States)

    Trenary, Tim; Graham, Eric A.; Stenzel, William; Rundel, Philip W.

    2015-01-01

    Azorella compacta (llareta; Apiaceae) forms dense, woody, cushions and characterizes the high elevation rocky slopes of the central Andean Altiplano. Field studies of an elevational gradient of A. compacta within Lauca National Park in northern Chile found a reverse J-shape distribution of size classes of individuals with abundant small plants at all elevations. A new elevational limit for A. compacta was established at 5,250 m. A series of cushions marked 14 years earlier showed either slight shrinkage or small degrees of growth up to 2.2 cm yr−1. Despite their irregularity in growth, cushions of A. compacta show a strong orientation, centered on a north-facing aspect and angle of about 20° from horizontal. This exposure to maximize solar irradiance closely matches previous observations of a population favoring north-facing slopes at a similar angle. Populations of A. compacta appear to be stable, or even expanding, with young plants abundant. PMID:25802811

  8. Size class structure, growth rates, and orientation of the central Andean cushion Azorella compacta

    Directory of Open Access Journals (Sweden)

    Catherine Kleier

    2015-03-01

    Full Text Available Azorella compacta (llareta; Apiaceae forms dense, woody, cushions and characterizes the high elevation rocky slopes of the central Andean Altiplano. Field studies of an elevational gradient of A. compacta within Lauca National Park in northern Chile found a reverse J-shape distribution of size classes of individuals with abundant small plants at all elevations. A new elevational limit for A. compacta was established at 5,250 m. A series of cushions marked 14 years earlier showed either slight shrinkage or small degrees of growth up to 2.2 cm yr−1. Despite their irregularity in growth, cushions of A. compacta show a strong orientation, centered on a north-facing aspect and angle of about 20° from horizontal. This exposure to maximize solar irradiance closely matches previous observations of a population favoring north-facing slopes at a similar angle. Populations of A. compacta appear to be stable, or even expanding, with young plants abundant.

  9. Seismic imaging of the upper mantle beneath the northern Central Andean Plateau: Implications for surface topography

    Science.gov (United States)

    Ward, K. M.; Zandt, G.; Beck, S. L.; Wagner, L. S.

    2015-12-01

    Extending over 1,800 km along the active South American Cordilleran margin, the Central Andean Plateau (CAP) as defined by the 3 km elevation contour is second only to the Tibetan Plateau in geographic extent. The uplift history of the 4 km high Plateau remains uncertain with paleoelevation studies along the CAP suggesting a complex, non-uniform uplift history. As part of the Central Andean Uplift and the Geodynamics of High Topography (CAUGHT) project, we use surface waves measured from ambient noise and two-plane wave tomography to image the S-wave velocity structure of the crust and upper mantle to investigate the upper mantle component of plateau uplift. We observe three main features in our S-wave velocity model including (1), a high velocity slab (2), a low velocity anomaly above the slab where the slab changes dip from near horizontal to a normal dip, and (3), a high-velocity feature in the mantle above the slab that extends along the length of the Altiplano from the base of the Moho to a depth of ~120 km with the highest velocities observed under Lake Titicaca. A strong spatial correlation exists between the lateral extent of this high-velocity feature beneath the Altiplano and the lower elevations of the Altiplano basin suggesting a potential relationship. Non-uniqueness in our seismic models preclude uniquely constraining this feature as an uppermost mantle feature bellow the Moho or as a connected eastward dipping feature extending up to 300 km in the mantle as seen in deeper mantle tomography studies. Determining if the high velocity feature represents a small lithospheric root or a delaminating lithospheric root extending ~300 km into the mantle requires more integration of observations, but either interpretation shows a strong geodynamic connection with the uppermost mantle and the current topography of the northern CAP.

  10. Serpentinitas y cromititas de La Cabaña, Cordillera de la Costa, Chile central

    OpenAIRE

    Fernando Barra; Osvaldo M Rabbia; Guillermo Alfaro; Hubert Miller; Christine Höfer; Stefan Kraus

    1998-01-01

    RESUMEN Las serpentinitas del área de La Cabaña forman parte de la Serie Occidental del Basamento Metamórfico de la Cordillera de la Costa de la IX Región y corresponden a dunitas de grano grueso parcial a totalmente serpentinizadas. Contienen cromita como mineral accesorio, la que generalmente está alterada en grado variable a ferricromita. En cambio, las cromitas presentes en las cromititas de Centinela Bajo, preservan su composición original con un mínimo grado de alteración, lo que permit...

  11. BANCO DE SEMILLAS EN UN BOSQUE DE ROBLE DE LA CORDILLERA CENTRAL COLOMBIANA SOIL SEED BANK IN AN OAK FOREST FROM THE COLOMBIAN CENTRAL CORDILLERA

    Directory of Open Access Journals (Sweden)

    Luz Bibiana Moscoso Marín

    2005-12-01

    they stores species ready to germinate when a perturbation occurs or when environmental conditions change to start the successional process. The main objective of this research was to evaluate the spatial variation of seed banks and its relation with the current vegetation in a highland Andean forest dominated by oak (Quercus humbodtii Bonpl. at 2.290 m.a.s.l. in the watershed of the Piedras Blancas stream, in the department of Antioquia, Colombia. We sampled 57 points in a 6.400 m² plot established in that forest. In each point we collected one sample each of litter and soil. We also established five subplots of 160 m²each for sampling vegetation. Seed banks were assessed by the method of direct germination. We obtained 204 trees belonging to 25 families and 41 genera. The most representative tree species were Alfaroa cf. colombiana, Myrcia popayanensis Rich. and Quercus humboldtii Bonpl. We obtained 428 individuals from soil samples and 113 individuals from litter samples in the germination trial, belonging to 20 morpho species. Species composition of the soil seed bank did not reflect the composition of the forest vegetation, and we found mainly herbaceous and shrub vegetation. Litter had 198 seeds m-2 and soil had 4.330 seeds m-2. There was large spatial variation in the amount of seeds in this forest fragment.

  12. A new colorful species of Pristimantis (Anura: Craugastoridae) from the eastern flank of the Cordillera Central in Colombia .

    Science.gov (United States)

    Rivera-Prieto, Diego A; Rivera-Correa, Mauricio; Daza, Juan M

    2014-01-01

    We describe a new species of Pristimantis from the humid forests on the eastern flank of the northern Cordillera Central in Colombia (6º 23' 19.3554" N, 75º 1' 24.0594" W; ca. 1150 m.a.s.l.). Pristimantis jaguensis sp. nov. is characterized by an extraordinary variation in color and is readily distinguished from congeneric species by lacking nuptial pads, discoidal fold and conical calcar tubercles; flanks and belly white to cream without blotches as well as iris yellow ocher to copper with thick brown reticulation and cream sclera. Molecular phylogenetic analyses recovered the new species in a clade with species mostly distributed in Ecuador. Our finding suggests that new taxa can still be discovered in the Middle Magdalena River valley of Colombia despite the extensive sampling this region has received during the last decades.  PMID:25543734

  13. Present and future water resources supply and demand in the Central Andes of Peru: a comprehensive review with focus on the Cordillera Vilcanota

    Science.gov (United States)

    Drenkhan, Fabian; Huggel, Christian; Salzmann, Nadine; Giráldez, Claudia; Suarez, Wilson; Rohrer, Mario; Molina, Edwin; Montoya, Nilton; Miñan, Fiorella

    2014-05-01

    Glaciers have been an important element of Andean societies and livelihoods as direct freshwater supply for agriculture irrigation, hydropower generation and mining activities. Peru's mainly remotely living population in the Central Andes has to cope with a strong seasonal variation of precipitations and river runoff interannually superimposed by El Niño impacts. Direct glacier and lake water discharge thus constitute a vital continuous water supply and represent a regulating buffer as far as hydrological variability is concerned. This crucial buffer effect is gradually altered by accelerated glacier retreat which leads most likely to an increase of annual river runoff variability. Furthermore, a near-future crossing of the 'peak water' is expected, from where on prior enhanced streamflow decreases and levels out towards a new still unknown minimum discharge. Consequently, a sustainable future water supply especially during low-level runoff dry season might not be guaranteed whereas Peru's water demand increases significantly. Here we present a comprehensive review, the current conditions and perspectives for water resources in the Cusco area with focus on the Vilcanota River, Cordillera Vilcanota, Southern Peru. With 279 km2 the Cordillera Vilcanota represents the second largest glacierized mountain range of the tropics worldwide. Especially as of the second half of the 1980s, it has been strongly affected by massive ice loss with around 30% glacier area decline until present. Furthermore, glacier vanishing triggers the formation of new lakes and increase of lake levels and therefore constitutes determining hazardous drivers for mass movements related to deglaciation effects. The Vilcanota River still lacks more profound hydrological studies. It is likely that its peak water has already been or might be crossed in near-future. This has strong implications for the still at 0.9% (2.2%) annually growing population of the Cusco department (Cusco city). People mostly

  14. Effect of human disturbance on seed and seedling distribution of the Andean Oak (Quercus humboldtii Bonpl., Fagaceae) in the Colombian Eastern Cordillera

    International Nuclear Information System (INIS)

    Animals affect the spatial occupation patterns of tropical forest plants throughout the seed dispersal they perform. Therefore, changes in vertebrate populations by human disturbance might affect re generation dynamics of plant species. We studied differences in the spatial distribution of seeds and seedlings of the Andean oak (Quercus humboldtii) between two nearby forests with contrasting levels of anthropogenic influence in the Colombian Andes. Density and spatial distribution of seedlings were evaluated in 490 and 484 1 m2 plots located in a 28 ha area, in the high and low disturbed site, respectively. In each plot, all seedlings found were sampled and classified into three age categories. Density and spatial distribution of seeds were evaluated in 0.25 m2subplots placed in the same plots described above. Results showed a higher number and density of seedlings in the high disturbed site, as well as a marked decrease in seedling density as age increases. Distances to the nearest neighbour were shorter in the high disturbed site for all seedlings and each age category, in contrast to the low disturbed site. Indexes of spatial distribution indicate an aggregated pattern in the most disturbed site, while a uniform pattern in the low disturbed one. Seeds also exhibited an aggregated pattern in the high disturbed site and a higher seed predation by invertebrates. Results seemed to be a consequence of forest fragmentation and a decrease of vertebrate seed dispersers, seed predators and herbivores associated to the regeneration processes of the species. These results provide important information for the forest management and restoration activities, since in order to maintain plant populations in the long term, presence and viable populations of seed dispersers should be also maintained.

  15. Un modelo de la historia de la vegetación de la Cordillera de La Costa de Chile central-sur: la hipótesis glacial de Darwin A model for the history of vegetation of the Coastal Range of central-southern Chile: Darwin's glacial hypothesis

    Directory of Open Access Journals (Sweden)

    CAROLINA VILLAGRÁN

    2001-12-01

    Andean and at high latitudes exist in south-central Chile, between 37 and 43° S. According to Darwin (1859, such "islands" are remnants of glacial populations, which were distributed at lower altitudes and latitudes during glacier advances. Also, in Chile there were expansions of the Andean and southernmost flora into the Longitudinal Valley of Los Lagos region during the last glaciation, which reversed during the Late-glacial (14, 600-10,000 14C years BP and Holocene (after 10,000 14C years BP. Considering this hypothesis, in this study we analyzed two palynological sequences from summits of the Coastal Range of Los Lagos region (Cordillera de Nahuelbuta and Cordillera de Sarao and both were correlated with published high and low altitude records from the Los Lagos and Los Canales regions. The records from the Coastal Range show the following chronological sequence: (1 at the lower and middle Holocene, after 9,040 14C years BP, the Cordillera de Sarao site documents the colonization of Magellanic moorlands and north-Patagonian forest elements, followed by north-Patagonian-Valdivian forest elements during the upper Holocene; (2 the Cordillera de Nahuelbuta site shows the development of conifer forest and Magellanic moorlands during the middle Holocene, ca. 5,430 14C years BP. Other palynological records from the Coastal Range (Cordillera Pelada and Cordillera de Piuchué show the development of both communities during the Late-glacial and lower Holocene. In contrast, the low altitude pollen records from the Los Lagos region indicate that conifers and magellanic moorland elements occupied the Longitudinal Valley during the Last Glacial Maximum (LGM, ca. 22,000 14C years BP. Various pollen profiles from Los Lagos and Los Canales regions evidenced for the late-glacial (14,600-10,000 14C years BP the rapid southern expansion of conifers and other north-Patagonian elements, following the deglaciation of these areas. During the Holocene, Valdivian forest elements invaded the

  16. 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...

  17. High-up: a remote reservoir of microbial extremophiles at Central Andean Wetlands

    Directory of Open Access Journals (Sweden)

    Virginia Helena Albarracín

    2015-12-01

    Full Text Available The Central Andes region displays unexplored ecosystems of shallow lakes and salt flats at mean altitudes of 3,700 m. Being isolated and hostile, these so-called High-Altitude Andean Lakes (HAAL are pristine and have been exposed to little human influence. HAAL proved to be a rich source of microbes showing interesting adaptations to life in extreme settings (poly-extremophiles such as alkalinity, high concentrations of arsenic and dissolved salts, intense dryness, large daily ambient thermal amplitude, and extreme solar radiation levels. This work reviews HAAL microbiodiversity, taking into account different microbial niches, such as plankton, benthos, microbial mats and microbialites. The modern stromatolites and other microbialites discovered recently at HAAL are highlighted, as they provide unique modern -though quite imperfect- analogues of environments proxy for an earlier time in Earth’s history (volcanic setting and profuse hydrothermal activity, low atmospheric O2 pressure, thin ozone layer and high UV exposure. Likewise, we stress the importance of HAAL microbes as model poly-extremophiles in the study of the molecular mechanisms underlying their resistance ability against UV and toxic or deleterious chemicals using genome mining and functional genomics. In future research directions, it will be necessary to exploit the full potential of HAAL poly-extremophiles in terms of their biotechnological applications. Current projects heading this way have yielded detailed molecular information and functional proof on novel extremoenzymes: i.e. DNA repair enzymes and arsenic efflux pumps for which medical and bioremediation applications, respectively, are envisaged. But still, much effort is required to unravel novel functions for this and other molecules that dwell in a unique biological treasure despite its being hidden high up, in the remote Andes.

  18. High-Up: A Remote Reservoir of Microbial Extremophiles in Central Andean Wetlands

    Science.gov (United States)

    Albarracín, Virginia H.; Kurth, Daniel; Ordoñez, Omar F.; Belfiore, Carolina; Luccini, Eduardo; Salum, Graciela M.; Piacentini, Ruben D.; Farías, María E.

    2015-01-01

    The Central Andes region displays unexplored ecosystems of shallow lakes and salt flats at mean altitudes of 3700 m. Being isolated and hostile, these so-called “High-Altitude Andean Lakes” (HAAL) are pristine and have been exposed to little human influence. HAAL proved to be a rich source of microbes showing interesting adaptations to life in extreme settings (poly-extremophiles) such as alkalinity, high concentrations of arsenic and dissolved salts, intense dryness, large daily ambient thermal amplitude, and extreme solar radiation levels. This work reviews HAAL microbiodiversity, taking into account different microbial niches, such as plankton, benthos, microbial mats and microbialites. The modern stromatolites and other microbialites discovered recently at HAAL are highlighted, as they provide unique modern—though quite imperfect—analogs of environments proxy for an earlier time in Earth's history (volcanic setting and profuse hydrothermal activity, low atmospheric O2 pressure, thin ozone layer and high UV exposure). Likewise, we stress the importance of HAAL microbes as model poly-extremophiles in the study of the molecular mechanisms underlying their resistance ability against UV and toxic or deleterious chemicals using genome mining and functional genomics. In future research directions, it will be necessary to exploit the full potential of HAAL poly-extremophiles in terms of their biotechnological applications. Current projects heading this way have yielded detailed molecular information and functional proof on novel extremoenzymes: i.e., DNA repair enzymes and arsenic efflux pumps for which medical and bioremediation applications, respectively, are envisaged. But still, much effort is required to unravel novel functions for this and other molecules that dwell in a unique biological treasure despite its being hidden high up, in the remote Andes. PMID:26733008

  19. Imaging the Seismic Cycle in the Central Andean Subduction Zone from Geodetic Observations

    Science.gov (United States)

    Ortega-Culaciati, F.; Becerra-Carreño, V. C.; Socquet, A.; Jara, J.; Carrizo, D.; Norabuena, E. O.; Simons, M.; Vigny, C.; Bataille, K. D.; Moreno, M.; Baez, J. C.; Comte, D.; Contreras-Reyes, E.; Delorme, A.; Genrich, J. F.; Klein, E.; Ortega, I.; Valderas, M. C.

    2015-12-01

    We aim to quantify spatial and temporal evolution of fault slip behavior during all stages of the seismic cycle in subduction megathrusts, with the eventual goal of improving our understanding of the mechanical behavior of the subduction system and its implications for earthquake and tsunami hazards. In this work, we analyze the portion of the Nazca-SouthAmerican plates subduction zone affected by the 1868 southern Peru and 1877 northern Chile mega-earthquakes. The 1868 and 1878 events defined a seismic gap that did not experience a large earthquake for over 124 years. Only recently, the 1995 Mw 8.1 Antofagasta, 2001 Mw 8.4 Arequipa, 2007 Mw 7.7 Tocopilla, and 2014 Mw 8.2 Pisagua earthquakes released only a small fraction of the potential slip budget, thereby raising concerns about continued seismic and tsunami hazard. We use over a decade of observations from continuous and campaign GPS networks to analyze inter-seismic strain accumulation, as well as co-seimic deformation associated to the more recent earthquakes in the in the Central Andean region. We obtain inferences of slip (and back-slip) behavior using a consistent and robust inversion framework that accounts for the spatial variability of the constraint provided by the observations on slip across the subduction megathrust. We present an updated inter-seismic coupling model and estimates of pre-, co- and post- seismic slip behavior associated with the most recent 2014 Mw 8.2 Pisagua earthquake. We analyze our results, along with published information on the recent and historical large earthquakes, to characterize the regions of the megathrust that tend to behave aseismically, and those that are capable to accumulate a slip budget (ultimately leading to the generation of large earthquakes), to what extent such regions may overlap, and discuss the potential for large earthquakes in the region.

  20. Crustal Magma Evolution: the View from the Chemistry of Large Central Andean Ignimbrites

    Science.gov (United States)

    Kay, S. M.; Coira, B.

    2006-12-01

    Voluminous andesitic to rhyodacitic ignimbritic fields linked to giant calderas are distinctive features of the Neogene magmatic record of the central Andean Altiplano-Puna plateau. These magmas evolved in a thickened backarc crust of an active subduction regime at a compressional margin. Their chemistry reflects the thermo-mechanical conditions that control the generation of large crustal magma systems, and tracks changes in a crust subjected to thickening, flow and delamination. Correlations with high resolution geophysical images help to decipher magma generation and eruption processes. A compilation of some 400 published and new chemical analyses allows a view of the spatial-temporal crustal evolution of large complexes in the Puna (22° -28°S) over the last 12 Ma. Data are from the 11-10 Ma Granada and Pairique, 9 to 8 Ma Vilama, 6.8 to 6.5 Ma Coranzulí, 6.7-6.1 Ma Panizos, 5.3-4 Ma Toconao, 4.2-3.8 Ma Atana, and 1.3 Ma Purico complexes in the north, the 12-10 Ma Aguas Calientes complex in the central Puna and the 5.1-3.6 Ma Laguna Amarga/Verde and 6.4 2.2 Ma Cerro Galan complexes in the south. A notable older to younger chemical trend that is seen is for La/Yb (40 to 10) and Sm/Yb (7.5 to 2) ratios to decrease without a corresponding pattern in Eu anomalies. This trend suggests a change from garnet to amphibole as a controlling residual phase at depth followed by feldspar fractionation at higher levels, possibly in magmas chambers near 20 km imaged by seismic data. Xenocrysts in mafic andesitic lavas could be phenocrysts from magmas at this level. A correlated temporal change to lower Al/(K+Na+Ca) and ^8^7Sr/^86Sr ratios and increasing epsilon Nd in the northern Puna requires a changing source linked to an evolving crust. Other patterns are better linked to regional basement differences and variability in the mantle-derived mafic magmas that supply the heat for melting.

  1. Calculo Preliminar de la Tasa de Meteorización del Batolito Antioqueño, Cordillera Central, Colombia

    Directory of Open Access Journals (Sweden)

    Carolina Garcia

    2010-04-01

    Full Text Available Este trabajo es una estimación preliminar del tiempo necesario para generar la espesa capa de saprolito que caracteriza el perfil de meteorización actual de un batolito cuarzodiorítico cretácico que aflora en altiplanos de la Cordillera Central de Colombia, entre 5º50' y 7º00' de latitud Norte y 74º50' y 75º35' de longitud Oeste y a alturas entre 750 y 2700 m.Se utilizan datos obtenidos previamente mediante el análisis de la composición química de las aguas superficiales de cuatro cuencas con áreas diferentes, ubicadas sobre el Batolito Antioqueño, al este de Medellín. Los cáculos se hicieron con el método basado en la pérdida de componentes en solución utilizando diferentes valores de solutos. Al utilizar la pérdida de sílice se obtiene un tiempo de meteorización de unos 6 x 10 6 años, comparable con el obtenido mediante la datación de las cenizas volcánicas mas antiguas que recubren la topografía actual y que indican la fecha mínima de configuración de la superficie de erosión.A pesar de resultar de una serie de suposiciones simplificadoras, este resultado es interesante y justifica la realización de determinaciones mas detalladas. Confirma la larga preservación de superficies de erosión antiguas conformadas sobre un saprolito que desde hace varios millones de años no ha sido sometido a una erosión profunda, fenómeno poco común en una zona tectónicamente activa como la estudiada.

  2. Migración boyacense en la Cordillera Central, 1876-1945Del altiplano cundiboyacense a los espacios de homogeneización antioqueña*

    OpenAIRE

    Ramírez Bacca, Renzo; Tobasura Acuña, Isaías

    2014-01-01

    El artículo ofrece un enfoque histórico-sociológico sobre el proceso migracional cundiboyacense en la cordillera central colombiana. Explica la evolución histórica y las fases de la migración, sus procesos socioculturales, interpreta las determinantes del fenómeno, y explica el perfil de su contacto y consecuente adaptación e integración con el elemento de ascendencia antioqueña en la zona de asentamiento. El espacio andino escogido —municipios del Líbano y Murillo en el departamento del Toli...

  3. Unraveling an antique subduction process from metamorphic basement around Medellín city, Central Cordillera of Colombian Andes

    Science.gov (United States)

    Bustamante, Andres; Juliani, Caetano

    2011-10-01

    varies between 400 and 555 °C at pressures of 5-6 kbar in the retrograde metamorphic path. The El Retiro rocks evidence strong decompression with narrow variation in temperature, showing pressure values between 8.7 and 2.7 kbar at temperatures of 740-633 °C. These metamorphic fragments of the basement in the Central Cordillera of the Colombian Andes could represent a close relationship with an antique subduction zone.

  4. Receiver functions and crustal structure of the northwestern Andean region, Colombia

    Science.gov (United States)

    Poveda, Esteban; Monsalve, Gaspar; Vargas, Carlos Alberto

    2015-04-01

    We used the receiver function technique to deduce crustal thickness beneath the northwestern Andean system, using data from the permanent seismic network of Colombia, combined with some of the IRIS and CTBTO stations in Colombia and Ecuador. The estimation of crustal thickness was made using the primary P to s conversion and crustal reverberations. The bulk crustal VP/VS ratio was constrained using a crustal thickness versus VP/VS stacking method, in addition to estimations using a time to depth conversion technique based on results of a modified Wadati diagram analysis. We observed a wide range of crustal thicknesses, including values around 17 km beneath the Malpelo Island on the Pacific Ocean, 20 to 30 km at the coastal Pacific and Caribbean plains of Colombia, 25 to 40 km beneath the eastern plains and foothills, 35 km beneath the Western Cordillera, 45 km at the Magdalena River intermountain valley, 52 to 58 km under the northern Central Cordillera, and reaching almost 60 km beneath some of the volcanoes of the Southern Cordilleran system of Colombia; crustal thickness can be slightly greater than 60 km beneath the plateau of the Eastern Cordillera. The values of VP/VS are particularly high for some of the stations on the volcanic centers, reaching values above 1.79, probably related to the addition of mafic materials to the lower crust, and in the plateau of the Eastern Cordillera near Bogota, where we speculate about the possibility of crustal seismic anisotropy associated with shear zones.

  5. Early and Middle Holocene evidence for plant use and cultivation in the Middle Cauca River Basin, Cordillera Central (Colombia)

    Science.gov (United States)

    Aceituno, Francisco J.; Loaiza, Nicolás

    2014-02-01

    This paper presents the latest results of research done in the Colombian Andean region known as Middle Cauca River Basin, an important location for the study of the origins of plant use and the dispersal of domesticates throughout the Americas due to its geographical position in northwest South America. We discuss human-environment interactions during Pleistocene/Holocene transition to middle Holocene (ca 10,000-4000 BP), specifically human-plant interaction and environmental factors that led to the adoption of horticultural practices. Three lines of evidence are analyzed: archaeological stratigraphy, lithic technology, and microbotanical remains. Our results suggest that early Holocene environmental stability allowed Middle Cauca settlers to use the diverse local resources for several millennia, altering the local vegetation, and leading to the development of horticultural practices that included the use of both local and foreign plants. These results inform the ongoing debate about the antiquity and nature of plant domestication and dispersals in the Americas.

  6. 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

  7. Andean waterways

    DEFF Research Database (Denmark)

    Rasmussen, Mattias Borg

    , social, and cultural concerns. Set in the highland town of Recuay in Ancash, the book traces the ways in which water affects political and ecological relations as glaciers recede. By looking at the shared waterways of four villages located in the foothills of Cordillera Blanca, it addresses pertinent...

  8. Studies in Neotropical Paleobotany. XV. A Mio-Pliocene palynoflora from the Eastern Cordillera, Bolivia: implications for the uplift history of the Central Andes.

    Science.gov (United States)

    Graham, A; Gregory-Wodzicki, K M; Wright, K L

    2001-09-01

    An assemblage of 33 fossil pollen and spores, recovered from the 3600-m high Pislepampa locality of E. W. Berry, Eastern Cordillera, Bolivia, adds considerably to our knowledge of three aspects of the region in late Neogene time: (1) the paleovegetation, (2) the paleoclimate, and (3) the paleoelevation of the Central Andes. The plant microfossils recognized are Isoetes, Lycopodium (three types), Cnemidaria, Cyathea (three types), Grammitis, Hymenophyllum, Pteris, trilete fern spores (two types), Danaea, monolete fern spores (four types), Podocarpus, Gramineae, Palmae, Ilex, cf. Oreopanax, Cavanillesia, cf. Pereskia, Compositae (three types), Ericaceae, Tetrorchidium, and unknowns (three types). The diversity of the Compositae suggest that this flora has a maximum age around the Miocene-Pliocene boundary, that is, 6-7 million years. All members of the paleocommunity presently grow in the bosque montano húmedo (cloud forest) along the eastern slope of the Central Andes of Bolivia, which occurs between MATs (mean annual temperatures) of ∼10° and 20°C. The Pislepampa flora probably represents the lower limits of this forest because the fossil leaves collected by Berry from the same locality all have entire margins, suggesting that the flora grew near the cloud forest-tropical forest transition. Presently, the lower limit of the cloud forest forest has MATs of ∼20°C, a mean annual precipitation between 1000 and 1500 mm, and that part containing most of the identified genera of fossil pollen is found at elevations ∼1200-1400 m. These conditions are thus inferred for the Pislepampa flora; however, because of the uncertainty of the magnitude of global climate change and of possible changes in the ecological range of plant genera, we estimate an error of at least ±1000 m for the paleoelevation estimate. When the total uplift is corrected for probable amounts of erosionally driven isostatic rebound, the paleoelevation estimate suggests that from one-third to one

  9. 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

  10. Large along-strike variations in the onset of Subandean exhumation: Implications for Central Andean orogenic growth

    Science.gov (United States)

    Lease, Richard O.; Ehlers, Todd A.; Enkelmann, Eva

    2016-10-01

    Plate tectonics drives mountain building in general, but the space-time pattern and style of deformation is influenced by how climate, geodynamics, and basement structure modify the orogenic wedge. Growth of the Subandean thrust belt, which lies at the boundary between the arid, high-elevation Central Andean Plateau and its humid, low-elevation eastern foreland, figures prominently into debates of orogenic wedge evolution. We integrate new apatite and zircon (U-Th)/He thermochronometer data with previously published apatite fission-track data from samples collected along four Subandean structural cross-sections in Bolivia between 15° and 20°S. We interpret cooling ages vs. structural depth to indicate the onset of Subandean exhumation and signify the forward propagation of deformation. We find that Subandean growth is diachronous south (11 ± 3 Ma) vs. north (6 ± 2 Ma) of the Bolivian orocline and that Subandean exhumation magnitudes vary by more than a factor of two. Similar north-south contrasts are present in foreland deposition, hinterland erosion, and paleoclimate; these observations both corroborate diachronous orogenic growth and illuminate potential propagation mechanisms. Of particular interest is an abrupt shift to cooler, more arid conditions in the Altiplano hinterland that is diachronous in southern Bolivia (16-13 Ma) vs. northern Bolivia (10-7 Ma) and precedes the timing of Subandean propagation in each region. Others have interpreted the paleoclimate shift to reflect either rapid surface uplift due to lithosphere removal or an abrupt change in climate dynamics once orographic threshold elevations were exceeded. These mechanisms are not mutually exclusive and both would drive forward propagation of the orogenic wedge by augmenting the hinterland backstop, either through surface uplift or spatially variable erosion. In summary, we suggest that diachronous Subandean exhumation was driven by piecemeal hinterland uplift, orography, and the outward

  11. Stable water isotope variation in a Central Andean watershed dominated by glacier and snowmelt

    Directory of Open Access Journals (Sweden)

    N. Ohlanders

    2013-03-01

    Full Text Available Central Chile is an economically important region for which water supply is dependent on snow- and ice melt. Nevertheless, the relative contribution of water supplied by each of those two sources remains largely unknown. This study represents the first attempt to estimate the region's water balance using stable isotopes of water in streamflow and its sources. Isotopic ratios of both H and O were monitored during one year in a high-altitude basin with a moderate glacier cover (11.5%. We found that the steep altitude gradient of the studied catchment caused a corresponding gradient in snowpack isotopic composition and that this spatial variation had a profound effect on the temporal evolution of streamflow isotopic composition during snowmelt. Glacier melt and snowmelt contributions to streamflow in the studied basin were determined using a quantitative analysis of the isotopic composition of streamflow and its sources, resulting in a glacier melt contribution of 50–90% for the unusually dry melt year of 2011/2012. This suggests that in (La Niña years with little precipitation, glacier melt is an important water source for central Chile. Predicted decreases in glacier melt due to global warming may therefore have a negative long-term impact on water availability in the Central Andes. The pronounced seasonal pattern in streamflow isotope composition and its close relation to the variability in snow cover and discharge presents a potentially powerful tool to relate discharge variability in mountainous, melt-dominated catchments with related factors such as contributions of sources to streamflow and snowmelt transit times.

  12. Depositional and provenance record of the Paleogene transition from foreland to hinterland basin evolution during Andean orogenesis, northern Middle Magdalena Valley Basin, Colombia

    Science.gov (United States)

    Moreno, Christopher J.; Horton, Brian K.; Caballero, Victor; Mora, Andrés; Parra, Mauricio; Sierra, Jair

    2011-10-01

    The Central Cordillera and Eastern Cordillera of the northern Andes form the topographic flanks of the north-trending Magdalena Valley Basin. Constraining the growth of these ranges and intervening basin has implications for Andean shortening and the transformation from a foreland to hinterland basin configuration. We present sedimentological, paleocurrent, and sandstone petrographic results from Cenozoic type localities to provide insights into the tectonic history of the northern Middle Magdalena Valley Basin of Colombia. In the Nuevo Mundo Syncline, the mid-Paleocene transition from marine to nonmarine deposystems of the Lisama Formation corresponds with a paleocurrent shift from northward to eastward transport. These changes match detrital geochronological evidence for a contemporaneous shift from cratonic (Amazonian) to orogenic (Andean) provenance, suggesting initial shortening-related uplift of the Central Cordillera and foreland basin generation in the Magdalena Valley by mid-Paleocene time. Subsequent establishment of a meandering fluvial system is recorded in lower-middle Eocene strata of the lower La Paz Formation. Eastward paleocurrents in mid-Paleocene through uppermost Eocene fluvial deposits indicate a continuous influence of western sediment source areas. However, at the upper middle Eocene (˜40 Ma) boundary between the lower and upper La Paz Formation, sandstone compositions show a drastic decrease in lithic content, particularly lithic volcanic fragments. This change is accompanied by a facies shift from mixed channel and overbank facies to thick, amalgamated braided fluvial deposits of possible fluvial megafans, reflecting changes in both the composition and proximity of western sediment sources. We attribute these modifications to the growing influence of exhumed La Cira-Infantas paleohighs in the axial Magdalena Valley, features presently buried beneath upper Eocene-Quaternary basin fill along the western flank of the Nuevo Mundo Syncline. In

  13. Remote sensing analysis for fault-zones detection in the Central Andean Plateau (Catamarca, Argentina)

    Science.gov (United States)

    Traforti, Anna; Massironi, Matteo; Zampieri, Dario; Carli, Cristian

    2015-04-01

    Remote sensing techniques have been extensively used to detect the structural framework of investigated areas, which includes lineaments, fault zones and fracture patterns. The identification of these features is fundamental in exploration geology, as it allows the definition of suitable sites for the exploitation of different resources (e.g. ore mineral, hydrocarbon, geothermal energy and groundwater). Remote sensing techniques, typically adopted in fault identification, have been applied to assess the geological and structural framework of the Laguna Blanca area (26°35'S-66°49'W). This area represents a sector of the south-central Andes localized in the Argentina region of Catamarca, along the south-eastern margin of the Puna plateau. The study area is characterized by a Precambrian low-grade metamorphic basement intruded by Ordovician granitoids. These rocks are unconformably covered by a volcano-sedimentary sequence of Miocene age, followed by volcanic and volcaniclastic rocks of Upper Miocene to Plio-Pleistocene age. All these units are cut by two systems of major faults, locally characterized by 15-20 m wide damage zones. The detection of main tectonic lineaments in the study area was firstly carried out by classical procedures: image sharpening of Landsat 7 ETM+ images, directional filters applied to ASTER images, medium resolution Digital Elevation Models analysis (SRTM and ASTER GDEM) and hill shades interpretation. In addition, a new approach in fault zone identification, based on multispectral satellite images classification, has been tested in the Laguna Blanca area and in other sectors of south-central Andes. In this perspective, several prominent fault zones affecting basement and granitoid rocks have been sampled. The collected fault gouge samples have been analyzed with a Field-Pro spectrophotometer mounted on a goniometer. We acquired bidirectional reflectance spectra, from 0.35μm to 2.5μm with 1nm spectral sampling, of the sampled fault rocks

  14. Seafloor Geodetic Monitoring of the Central Andean Subduction Zone: The Geosea Array

    Science.gov (United States)

    Kopp, H.; Lange, D.; Contreras Reyes, E.; Behrmann, J. H.; McGuire, J. J.; Flueh, E. R.

    2014-12-01

    Seafloor geodesy has been identified as one of the central tools in marine geosciences to monitor seafloor deformation at high resolution. To quantify strain accumulation and assess the resultant hazard potential we urgently need systems to resolve seafloor crustal deformation. The GeoSEA (Geodetic Earthquake Observatory on the Seafloor) array consists of a seafloor transponder network comprising a total of 35 units and a wave glider acting as a surface unit (GeoSURF) to ensure satellite correspondence, data transfer and monitor system health. For horizontal direct path measurements, the system utilizes acoustic ranging techniques with a ranging precision better than 15 mm and long term stability over 2 km distance. Vertical motion is obtained from pressure gauges. Integrated inclinometers monitor station settlement in two horizontal directions. Travel time between instruments and the local water sound velocity will be recorded autonomously subsea without system or human intervention for up to 3.5 years. Data from the autonomous network on the seafloor can be retrieved via the integrated high-speed acoustic telemetry link without recovering the seafloor units. In late 2015 GeoSEA will be installed on the Iquique segment of the South America - Nazca convergent plate boundary to monitor crustal deformation. The Iquique seismic gap experienced the 2014 Mw 8.1 Pisagua earthquake, which apparently occurred within a local locking minimum. It is thus crucial to better resolve resolve strain in the forearc between the mainland and the trench in order to improve our understanding of forearc deformation required for hazard assessment. Mobile autonomous seafloor arrays for continuous measurement of active seafloor deformation in hazard zones have the potential to lead to transformative discoveries of plate boundary/fault zone tectonic processes and address a novel element of marine geophysical research.

  15. Slab flattening, dynamic topography and normal faulting in the Cordillera Blanca region (northern Peru)

    Science.gov (United States)

    Margirier, A.; Robert, X.; Laurence, A.; Gautheron, C.; Bernet, M.; Simon-Labric, T.; Hall, S. R.

    2015-12-01

    Processes driving surface uplift in the Andes are still debated and the role of subduction processes as slab flattening on surface uplift and relief building in the Andes is not well understood. Some of the highest Andean summits, the Cordillera Blanca (6768 m) and the Cordillera Negra (5187 m), are located above a present flat subduction zone (3-15°S), in northern Peru. In this area, both the geometry and timing of the flattening of the slab are well constrained (Gutscher et al., 1999; Rosenbaum et al., 2005). This region is thus a perfect target to explore the effect of slab flattening on the Andean topography and uplift. We obtained new apatite (U-Th)/He and fission-track ages from three vertical profiles located in the Cordillera Blanca and the Cordillera Negra. Time-temperature paths obtained from inverse modeling of the thermochronological data indicates a Middle Miocene cooling for both Cordillera Negra profiles. We interpret it as regional exhumation in the Cordillera Occidental starting in Middle Miocene, synchronous with the onset of the subduction of the Nazca ridge (Rosenbaum et al., 2005). We propose that the Nazca ridge subduction at 15 Ma and onset of slab flattening in northern Peru drove regional positive dynamic topography and thus enhanced exhumation in the Cordillera Occidental. This study provides new evidence of the impact subduction processes and associated dynamic topography on paleogeography and surface uplift in the Andes.

  16. Las bioconstrucciones de corales y sus facies asociadas durante el Malm en la Cordillera Ibérica Central (provincia de Zaragoza

    Directory of Open Access Journals (Sweden)

    Meléndez, A.

    1987-08-01

    Full Text Available The differents types of bioconstructions and associated facies in the Central Iberian Chain (Higueruelas Formation, Upper Kimmeridgian have been studied. Biohermes of different thickness (decimetric to metric and less lateral continuity are developped, highly colonized by corals, that are associated to oncolitic, bioclastic and oolitic of high energy facies, in marginal areas, near the litoral developpment. At the same time takes place an important set up of mud mounds, with a small coral colonisation, in protected arcas in a inner shelf, or in outer areas, where the action of the waves is not so effective. The environment protection is been generated in some places due to the appearance of oolitic barrier islands.Se estudian los diferentes tipos de bioconstrucciones de corales, y sus facies asociadas, presentes en el sector central de la rama aragonesa de la Cordillera Ibérica, en la Formación Higueruelas (Kimmeridgiense superior. Se desarrollan biohermos de potencias métricas a decimétricas y escasa continuidad lateral, intensamente colonizados por corales coloniales, que se encuentran asociados a facies oncolíticas, bioclásticas y oolíticas de alta energía en zonas marginales, próximas al desarrollo litoral. Al mismo tiempo tiene lugar una importante instalación de mud mounds, con escasa colonización de corales, en zonas protegidas dentro de la plataforma interna o en zonas más externas, donde la acción del oleaje no es efectiva. La protección del medio viene condicionada en algunos puntos por la aparición de islas barrera oolíticas.

  17. Caracterización de superficies de erosión mediante geomorfología cuantitativa, Altiplano Antioqueño, Cordillera Central de Colombia

    Directory of Open Access Journals (Sweden)

    Xavier Bustos

    2013-01-01

    Full Text Available En el presente trabajo se caracterizan treinta y cinco superficies de erosión (SE en la Cordillera Central de Colombia mediante geomorfología cuantitativa y análisis digital de terreno. Utilizando modelos digitales de elevación (MDE se derivaron las curvas hipsométricas para dichas superficies, y se comparan los resultados desde dos ópticas. Primero, mediante técnicas geoestadísticas utilizando subrutinas elaboradas bajo R, en combinación con el Lenguaje de Consulta Estructurado (SQL. Segundo, mediante sus respectivos valores de integral hipsométrica, lo que permitió discriminar el grado de madurez, juventud y vejez de las mismas. Desde un vista geomático este trabajo contribuye en el empleo de Bases de Datos Geográficas (Geodatabase lo que permite optimizar el tiempo y el número de cálculos en el procesamiento, todo esto fue integrado usando Sistemas de Información Geográfica (SIG. Los resultados obtenidos acá permiten caracterizar las superficies y relacionar su morfología con fenómenos físicos y climáticos tales como: levantamiento superficial del terreno, erosión, incisión de ríos y presencia de fallas. Adicionalmente, este enfoque multidisciplinario podría ser utilizado para caracterizar topo-formas remanentes a lo largo de Suramérica, las cuales son de vital importancia ya que contienen información de la interacción de procesos climáticos y tectónicos a lo largo del tiempo geológico.

  18. Landsat TM and ETM+ derived snowline altitudes in the Cordillera Huayhuash and Cordillera Raura, Peru, 1986–2005

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    J. Ramage

    2010-10-01

    Full Text Available The Cordilleras Huayhuash and Raura are remote glacierized ranges in the Andes Mountains of Peru. A robust assessment of modern glacier change is important for understanding how regional change affects Andean communities, and for placing paleo-glaciers in a context relative to modern glaciation and climate. Snowline altitudes (SLAs derived from satellite imagery are used as a proxy for modern (1986–2005 local climate change in a key transition zone in the Andes. Clear sky, dry season Landsat Thematic Mapper (TM and Enhanced Thematic Mapper (ETM+ satellite images from 1986–2005 were used to identify snowline positions, and their altitude ranges were extracted from an Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER DEM. Based on satellite records from 31 glaciers, mean snowline altitudes (SLAs, an approximation for the equilibrium line altitudes (ELAs, for the Cordillera Huayhuash (13 glaciers and Cordillera Raura (18 glaciers were 5046 m a.s.l. and 5013 m a.s.l., respectively, from 1986–2005. The rate of SLA rise was 25 m/decade in the Cordillera Huayhuash and 62 m/decade in the Cordillera Raura.

  19. Landsat TM and ETM+ derived snowline altitudes in the Cordillera Huayhuash and Cordillera Raura, Peru, 1986–2005

    Directory of Open Access Journals (Sweden)

    J. Ramage

    2011-05-01

    Full Text Available The Cordilleras Huayhuash and Raura are remote glacierized ranges in the Andes Mountains of Peru. A robust assessment of modern glacier change is important for understanding how regional change affects Andean communities, and for placing paleo-glaciers in a context relative to modern glaciation and climate. Snowline altitudes (SLAs derived from satellite imagery are used as a proxy for modern (1986–2005 local climate change in a key transition zone in the Andes. Clear sky, dry season Landsat Thematic Mapper (TM and Enhanced Thematic Mapper (ETM+ satellite images from 1986–2005 were used to identify snowline positions, and their altitude ranges were extracted from an Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER digital elevation model (DEM. Based on satellite records from 31 glaciers, average snowline altitudes (SLAs, an approximation for the equilibrium line altitude (ELA, for the Cordillera Huayhuash (13 glaciers and Cordillera Raura (18 glaciers from 1986–2005 were 5051 m a.s.l. from 1986–2005 and 5006 m a.s.l. from 1986–2002, respectively. During the same time period, the Cordillera Huayhuash SLA experienced no significant change while the Cordillera Raura SLA rose significantly from 4947 m a.s.l. to 5044 m a.s.l.

  20. Rodent consumption by Philodryas psammophidea (Serpentes: Colubridae), from the inter-andean dry valleys of central Bolivia

    OpenAIRE

    Quinteros-Muñoz, Oliver; Peñaranda, Diego A.; Navarro, Freddy

    2010-01-01

    In May 18, 2009 we found an adult female of Philodryas psammophidea (930 mm SVL), at a side of a crop field in the Tabacal valley (18º23'7.42" S – 64º38'7.88" W, 2015 m), Narciso Campero province southern Cochabamba, Bolivia. Ecologically, this valley belongs to the Inter-Andean Dry Forests of Bolivia. In the stomach of the snake probably killed by a settler, there was an adult female of Graomys domorum (Phyllotini; Sigmodontidae), a native rodent species widely distributed in the r...

  1. Rodent consumption by Philodryas psammophidea (Serpentes: Colubridae, from the inter-andean dry valleys of central Bolivia

    Directory of Open Access Journals (Sweden)

    Quinteros-Muñoz, Oliver

    2010-12-01

    Full Text Available In May 18, 2009 we found an adult female of Philodryas psammophidea (930 mm SVL, at a side of a crop field in the Tabacal valley (18º23'7.42" S – 64º38'7.88" W, 2015 m, Narciso Campero province southern Cochabamba, Bolivia. Ecologically, this valley belongs to the Inter-Andean Dry Forests of Bolivia. In the stomach of the snake probably killed by a settler, there was an adult female of Graomys domorum (Phyllotini; Sigmodontidae, a native rodent species widely distributed in the region.

  2. Diversidad florística y estructura de remanentes de bosque andino en la zona de amortiguación del parque nacional natural los nevados, cordillera central colombiana

    OpenAIRE

    Franco, Marcela; Betancur, Julio; Franco, Pilar

    2012-01-01

    Se caracterizó la diversidad, la composición fl orística y la estructura de los bosquesde la Reserva Torre Cuatro, la cual hace parte de la zona amortiguadora del ParqueNacional Natural Los Nevados, Cordillera Central de los Andes colombianos. Losremanentes de bosque se subdividieron en tres zonas de acuerdo a la altitud: baja(2650-2900 m), media (3000-3300 m) y alta (3400-3750 m), en cada una de las cualesse muestreó 0.1 ha y se censaron todos los individuos con DAP ≥ 2.5 cm. La riquezade es...

  3. Sediment budget in the Ucayali River basin, an Andean tributary of the Amazon River

    OpenAIRE

    W. Santini; Martinez, J. -M.; Espinoza-Villar, R.; G. Cochonneau; Vauchel, P.; Moquet, J.-S.; Baby, P.; Espinoza, J.-C.; Lavado, W.; Carranza, J.; Guyot, J.-L.

    2015-01-01

    Formation of mountain ranges results from complex coupling between lithospheric deformation, mechanisms linked to subduction and surface processes: weathering, erosion, and climate. Today, erosion of the eastern Andean cordillera and sub-Andean foothills supplies over 99% of the sediment load passing through the Amazon Basin. Denudation rates in the upper Ucayali basin are rapid, favoured by a marked seasonality in this region and extreme precipitation cells above sedimentary strata, uplifted...

  4. The origin and crust/mantle mass balance of Central Andean ignimbrite magmatism constrained by oxygen and strontium isotopes and erupted volumes

    Science.gov (United States)

    Freymuth, Heye; Brandmeier, Melanie; Wörner, Gerhard

    2015-06-01

    Volcanism during the Neogene in the Central Volcanic Zone (CVZ) of the Andes produced (1) stratovolcanoes, (2) rhyodacitic to rhyolitic ignimbrites which reach volumes of generally less than 300 km3 and (3) large-volume monotonous dacitic ignimbrites of up to several thousand cubic kilometres. We present models for the origin of these magma types using O and Sr isotopes to constrain crust/mantle proportions for the large-volume ignimbrites and explore the relationship to the evolution of the Andean crust. Oxygen isotope ratios were measured on phenocrysts in order to avoid the effects of secondary alteration. Our results show a complete overlap in the Sr-O isotope compositions of lavas from stratovolcanoes and low-volume rhyolitic ignimbrites as well as older (>9 Ma) large-volume dacitic ignimbrites. This suggests that the mass balance of crustal and mantle components are largely similar. By contrast, younger (70 km3 Ma-1 km-1 (assuming plutonic/volcanic ratios of 1:5) which are additional to, but within the order of, the arc background magmatic flux. Comparing our results to average shortening rates observed in the Andes, we observe a "lag-time" with large-volume eruptions occurring after accelerated shortening. A similar delay exists between the ignimbrite pulses and the subduction of the Juan Fernandez ridge. This is consistent with the idea that large-volume ignimbrite eruptions occurred in the wake of the N-S passage of the ridge after slab steepening has allowed hot asthenospheric mantle to ascend into and cause the melting of the mantle wedge. In our model, the older large-volume dacitic ignimbrites in the northern part of the CVZ have lower (15-37 %) crustal contributions because they were produced at times when the Central Andean crust was thinner and colder, and large-scale melting in the middle crust could not be achieved. Younger ignimbrite flare-ups further south (22°S) formed with a significantly higher crustal contribution (22-68 %) because at that

  5. A new minute Andean Pristimantis (Anura: Strabomantidae from Venezuela

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    César L. Barrio-Amorós

    2012-12-01

    Full Text Available A new species of Pristimantis is described from the Venezuelan Andes. The new species is the smallest in its genus known in Venezuela and belongs to the Pristimantis unistrigatus Group. It differs from the rest of Venezuelan Andean congeners in body size (mean male SVL < 21.3 mm, female SVL < 26.3 mm, expanded discs on fingers and toes, absence of dorsolateral folds, and a distinctivecall consisting in 2–5 cricket-like short notes. The new species inhabits the southwestern part of the Cordillera de Mérida in Venezuela and the Venezuelan side of the Cordillera Oriental deColombia, and could be present on the Colombian portion of the cordillera as well.

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

    Science.gov (United States)

    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. Magmatic evidence for Neogene lithospheric evolution of the central Andean ``flat-slab'' between 30°S and 32°S

    Science.gov (United States)

    Kay, S. M.; Abbruzzi, J. M.

    1996-06-01

    Geochemical data from Andean Miocene magmas erupted through the now volcanically-inactive "flat-slab" between 30°S to 32°S, coupled with geological and geophysical data, illuminate details on magmatic and continental lithospheric evolution over a progressively shallowing subduction zone. Pb, Sr and Nd isotopic and trace-element data show that Main Cordilleran, Precordilleran and Pampean magmas were contaminated in both the mantle and crust, and that the nature of the contaminants varied in time and space, reflecting tectonic events. Contaminants included both "enriched" (high LIL-element, high Sr and Pb, and low Nd isotopic ratios) and "depleted" (low LILE-element, low Sr and Pb, and high Nd isotopic ratios) types. In the western region, Main Cordilleran earlier Miocene lavas had contaminants with less "enriched" signatures than later Miocene lavas. Progressive "enrichment" is attributed to: (a) increasing amounts of sediment and tectonically eroded crust being subducted into the mantle wedge; and (b) contamination in a thickening Main Cordilleran lower crust whose composition was progressively "enriched". This "enrichment" occurred through addition of upper crust by an intracrustal mixing process driven by a propagating wedge tip associated with westward wedging, heating and deformation of crust from beneath the shortening Precordillera thrust belt to the east. Further east, magmas erupted through back-arc crust have more "depleted" signatures. Those erupted in the central part through the evolving Precordilleran thrust belt were contaminated by an older, thinner Grenville (˜ 1100 Ma) basement whose "depleted" signature is unique among Central Andean terranes. Late Miocene Pocho lavas erupted further east in conjunction with uplift of the Sierras Pampeanas show "enrichment" through time. Arguably, these magmas could contain a component mechanically removed from the base of the thinning continental lithosphere to the west, and progressively incorporated into the

  8. Estructura comunitaria de diatomeas presentes en los sedimentos superficiales de ocho lagos andinos de Chile central Diatoms community structure in superficial sediments of eight Andean lakes of central Chile

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    INGRID E ALVIAL

    2008-03-01

    Full Text Available En este trabajo se analizó la estructura comunitaria de diatomeas depositadas en los sedimentos superficiales de ocho lagos andinos chilenos ubicados entre los 32°49' y 38°48' S. Se encontró un total de 99 taxa de diatomeas, distribuidos en 48 géneros. Del total de taxa, 74 fueron identificados a nivel de especie siendo todos ellos cosmopolitas a excepción de Eunotia andinofrequens, Gomphonema punae, Pinnularia araucanensis y Pinnularia acidicola, entre otras, que están descritos solo para el Hemisferio Sur. Por otro lado, las muestras analizadas presentaron distinta composición florística de diatomeas. De esta manera, en los ensambles diatomológicos depositados en los sedimentos de las lagunas de altura Ocho, Huifa, Ensueño y Negra ubicadas sobre los 2.860 m del nivel del mar, abundaron especies bentónicas, típicas de aguas oligotróficas y acidas como Achnanthidium exiguum, Achnanthidium minutissimum, Encyonema minutum, Pinnularia acidicola y Planothidium lanceolatum. En los ensambles diatomológicos de los lagos Galletué, Icalma y Laja, ubicados bajo los 1.360 m del nivel del mar, abundaron diatomeas planctónicas, características de aguas alcalinas y mesotróficas como Asterionella formosa, Aulacoseira distans, Aulacoseira granulata, Cyclotella stelligera y Rhopalodia gibbaIn this research the taxonomic structure of diatoms in sediments of high mountain lakes was studied. These lakes are located in Chile between 32°49' and 38°48' S in the Andean Cordillera. A total of 99 diatom taxa distributed in 48 genera were identified and all this taxa are cosmopolitan excepting a Eunotia andinofrequens, Gomphonema punae, Pinnularia araucanensis and Pinnularia acidicola, which are know only for the Southern Hemisphere. The assemblages of diatoms were different in the studied lakes. So the high mountain lakes Ocho, Huifa, Ensueño and Negra, dominated benthic diatoms which are typical of oligotrophic and acid waters as Achnanthidium

  9. Late Quaternary geomorphic history of a glacial landscape - new sedimentary and chronological data from the Cordillera de Cochabamba (Bolivia)

    Science.gov (United States)

    May, J.-H.; Preusser, F.; Zech, R.; Ilgner, J.; Veit, H.

    2009-04-01

    Throughout the Central Andes, glacial landscapes have long been used for the reconstruction of Late Quaternary glaciations and landscape evolution. Much work has focused on the Andes in Peru, Chile and the Bolivian Altiplano, whereas relatively little data has been published on glaciation history in the eastern Andean ranges and slopes. Even less is known with regard to the postglacial evolution of these glacial landscapes. In the Cordillera de Cochabamba (Bolivia), local maximum advances probably peaked around 20-25 ka BP and were followed by significant readvances between ~12-16 ka BP. This generally points to temperature controlled maximum glacial advances along the humid eastern slopes of the Central Andes, which is supported by glacier-climate-modelling studies. However, most studies include only marginal information with regard to the complex geomorphic and sedimentary situation in the Cordillera de Cochabamba. Furthermore, the chronological results are afflicted with several methodological uncertainties inherent to surface exposure dating and call for application of alternative, independent age dating methods. Therefore this study aims at i) documenting and interpreting the complex glacial geomorphology of the Huara Loma valley in the Cordillera de Cochabamba (Bolivia), ii) analyzing the involved units of glacial sediments, and iii) improving the chronological framework by applying optically stimulated luminescence (OSL) and radiocarbon dating (14C). For this purpose, geomorphic mapping was combined with field documentation of sedimentary profiles. The involved sediments were subject to geochemical and mineralogical analysis in order to deduce information on their erosional and weathering histories. In addition, the interpretation of OSL ages from glacial and proglacial sediments integrated several methodological procedures with regard to sample preparation and statistical analysis of the measurements in order to increase the degree of confidence. These

  10. Variables Associated with Utilization of a Centralized Medical Post in the Andean Community of Pampas Grande, Peru

    Science.gov (United States)

    Merry, Stephen P.; Rohrer, James E.; Thacher, Thomas D.; Summers, Matthew R.; Alpern, Jonathan D.; Contino, Robert W.

    2012-01-01

    Context: Integral to the location of health resources is the distance decay of utilization observed in a population. In rural Peru, a nongovernmental organization planning to increase the availability of health services needed this information. Purpose: To determine variables associated with utilization of a central medical clinic and determine…

  11. Andean region: a shapefile of Morrone's (2015) biogeographical regionalisation.

    Science.gov (United States)

    Löwenberg-Neto, Peter

    2015-01-01

    Morrone's (2015) biogeographic regionalisation of the Andean region is based on the distributional ranges of terrestrial plants and animals. It is the most comprehensive and methodologically supported biogeographical scheme for the region to date. The Andean region comprises one transition zone (the South American transition zone), three subregions (Central Chilean, Subantarctic and Patagonian) and 15 provinces (Morrone, 2015). PMID:26250168

  12. 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

  13. 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

  14. Phylogenetic insights into Andean plant diversification

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    Federico eLuebert

    2014-06-01

    Full Text Available Andean orogeny is considered as one of the most important events for the developmentof current plant diversity in South America. We compare available phylogenetic studies anddivergence time estimates for plant lineages that may have diversified in response to Andeanorogeny. The influence of the Andes on plant diversification is separated into four major groups:The Andes as source of new high-elevation habitats, as a vicariant barrier, as a North-Southcorridor and as generator of new environmental conditions outside the Andes. Biogeographicalrelationships between the Andes and other regions are also considered. Divergence timeestimates indicate that high-elevation lineages originated and diversified during or after the majorphases of Andean uplift (Mid-Miocene to Pliocene, although there are some exceptions. Asexpected, Andean mid-elevation lineages tend to be older than high-elevation groups. Mostclades with disjunct distribution on both sides of the Andes diverged during Andean uplift.Inner-Andean clades also tend to have divergence time during or after Andean uplift. This isinterpreted as evidence of vicariance. Dispersal along the Andes has been shown to occur ineither direction, mostly dated after the Andean uplift. Divergence time estimates of plant groupsoutside the Andes encompass a wider range of ages, indicating that the Andes may not benecessarily the cause of these diversifications. The Andes are biogeographically related to allneighbouring areas, especially Central America, with floristic interchanges in both directionssince Early Miocene times. Direct biogeographical relationships between the Andes and otherdisjunct regions have also been shown in phylogenetic studies, especially with the easternBrazilian highlands and North America. The history of the Andean flora is complex and plantdiversification has been driven by a variety of processes, including environmental change,adaptation, and biotic interactions

  15. Vegetation composition and altitudinal distribution of Andean rain forests in El Angel and Guandera reserves, northern Ecuador

    NARCIS (Netherlands)

    Moscol Olivera, M.C.; Cleef, A.M.

    2009-01-01

    Patterns of vascular plant species composition and structure of the remaining rain forest of the Andean Cordillera in northern Ecuador were studied in two reserves: Guandera and El Angel. Thirty three plots located between 3300 and 3700 in were examined along two altitudinal transects crossing the U

  16. Caracterización Física, Química y Mineralógica de Suelos con Vocación Forestal Protectora Región Andina Central Colombiana / Physical Chemical and Mineralogical Characterization of Soils with a Protective Forest Vocation, Central Andean Region of Colombia

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    Leyder Echeverri Tafur

    2014-06-01

    Full Text Available Resumen. En la Reserva Forestal Protectora Bosques de la CHEC, ubicada sobre la vertiente occidental de la cordillera central colombiana, municipios de Manizales y Villamaría, departamento de Caldas, se hizo la caracterización física, química y mineralógica de dos perfiles de suelos, descritos sobre dos laderas, con un manejo actual correspondiente a una plantación de aliso (Alnus acuminata y un bosque secundario. Los resultados permitieron establecer,desde el punto de vista físico, el dominio de clase textural areno francosa en la plantación de aliso y franco arenoso en el bosque secundario. Químicamente el suelo del perfil plantado con aliso, presentó valores de pH más bajos, mayor saturación de acidez intercambiable y menor saturación de bases en comparación con el perfil del bosque secundario. En ambos perfiles, el análisis óptico con microscopio petrográfico, permitió observar que los feldespatos, del grupo de las plagioclasas y el vidrio volcánico, se destacan como minerales abundantes en la fracción arena; mientras que en la fracción arcilla, el material no cristalino, seconsidera mineral predominante, seguido de la cristobalita y los feldespatos, según la metodología de difracción de rayos X. Se concluye que la vocación de uso forestal protector, bajo el cual se encuentran sometidos ambos suelos, es el más adecuado, teniendo en cuenta que las limitaciones químicas, dificultan el establecimiento de sistemas de producción agropecuaria. / Abstract. The physical, chemical and mineralogical characterization of two soil profiles on two slopes, with a management currently corresponding to an Andean alder plantation (Alnus acuminata and a secondary forest, was carried out at the Protective Forest Reserve of the CHEC. This reserve is located on the western slope of the Central Mountain Range of the Colombian Andes, in the municipalities of Manizales and Villamaria, Caldas Department. The results

  17. Estratigrafía del Pérmico y Triásico en el sector central de la rama castellana de la Cordillera Ibérica.

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    Pérez-Arlucea, M.

    1985-08-01

    Full Text Available The main Permian and Triassic sequence in Molina de Aragón and South Albarracín is established. More than 45 sections have been studied, analysing the lateral changes and establishing 16 lithoestratigraphic Units. Part of these 1ithoestraigraphic Units were originally established by Ramos (1979 in the Molina de Aragon area, but this study prove that they can be followed to our arca. .
    The description, main characteristics, lateral changes and extension of each lithoestratigraphic Units are established here. .
    The paleogeography of this area with a large high located in the half north of Albarracín Sierra, is discussed here. That high was related with the tectonic movements contemporaneous to sedimentation during Upper Permian and Triassic.

    Se establece la sucesión estratigráfica tipo del Pérmico y Triásico de la región comprendida entre Molina de Aragón y el sur de Albarracín. Sobro la base do más de 45 columnas estratigráficas levantadas y del análisis de las variaciones que presentan los distintos tramos litológicos de que se compone la serie, se establecen 16 unidades litoestratigráficas, Aunque una parte de estas unidades fueron definidas originalmente en otros sectores de la Cordillera Ibérica, el estudio realizado demuestra que son también válidas en este área. Es el caso de las unidades definidas para parte del Pérmico y para las facies Buntsandstein por Ramos (1979, al oeste de Molina de Aragón.
    Se describen y analizan las principales características de cada una de las unidades litoestratigráficas establecidas. así como sus variaciones laterales y extensión superficial. .
    Por último, se discuten las implicaciones paleogeográficas que tuvo la existencia de un importante umbral situado en la mitad norte de la Sierra de Albarracín, Y se relaciona su presencia con la actividad tectónica contemporánea de la sedimentación del Pérmico superior y del Triásico.

  18. 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

  19. Species richness and indices of abundance of medium-sized mammals in andean forest and reforestations with andean alder: a preliminary analysis

    OpenAIRE

    Sánchez, Francisco; SÁNCHEZ-PALOMINO, PEDRO; CADENA, ALBERTO

    2013-01-01

    We studied the species richness and two indices of abundance of medium-sizedmammals in areas with Andean forest and Andean alder (Alnus acuminata)reforestations in a reserve at the Central Andes of Colombia. Since reforested areashave a less complex habitat structure and lower plant diversity than native forests, wepredicted that they have lower richness of mammals than areas with Andean forest.We obtained the indices of abundance from direct contacts in transects and from theuse of track sta...

  20. Rodent consumption by Philodryas psammophidea (Serpentes: Colubridae), from the Inter-andean Dry Valleys of Central Bolivia

    OpenAIRE

    Quinteros Muñoz, Oliver; Peñaranda, Diego A.; Navarro, Freddy

    2010-01-01

    In May 18, 2009 we found an adult female of Philodryas psammophidea (930 mm SVL), at a side of a crop field in the Tabacal valley (18º23’7.42” S – 64º38’7.88”W, 2015 m), Narciso Campero province southern Cochabamba, Bolivia. Ecologically, this valley belongs to the Inter-Andean Dry Forests of Bolivia. In the stomach of thesnake probably killed by a settler, therewas an adult female of Graomys domorum (Phyllotini; Sigmodontidae), a native rodent species widely distributed in the region....

  1. New KAr age determinations of intrusive rocks from the Cordillera Occidental and Altiplano of central Peru: Identification of magmatic pulses and episodes of mineralization

    Science.gov (United States)

    Soler, P.; Bonhomme, M. G.

    The post-Albian evolution of the Andes of central Peru is characterized by igneous activity, both effusive and intrusive, and by at least six distinct episodes of compressional tectonics. New KAr age determinations have been made of intrusive rocks from the Cajatambo-Oyón-Cerro de Pasco area. In conjunction with already published information, these new data permit a better estimate of the ages and the lateral extent of successive Cenozoic magmatic arcs. Metallogenetic implications of the 26.3-29.3 Ma age of mineralized Milpo-Atacocha intrusions are also discussed.

  2. Caracterización física, química y mineralógica de suelos con vocación forestal protectora región andina central colombiana / physical chemical and mineralogical characterization of soils with a protective forest vocation, central andean region of colombia

    OpenAIRE

    Leyder Echeverri Tafur; Jaime Vicente Estévez Varón; Juan Guillermo Bedoya Patiño

    2014-01-01

    Resumen. En la Reserva Forestal Protectora Bosques de la CHEC, ubicada sobre la vertiente occidental de la cordillera central colombiana, municipios de Manizales y Villamaría, departamento de Caldas, se hizo la caracterización física, química y mineralógica de dos perfiles de suelos, descritos sobre dos laderas, con un manejo actual correspondiente a una plantación de aliso (Alnus acuminata) y un bosque secundario. Los resultados permitieron establecer,desde el punto de vista físico, el domin...

  3. Sediment budget in the Ucayali River basin, an Andean tributary of the Amazon River

    Science.gov (United States)

    Santini, W.; Martinez, J.-M.; Espinoza-Villar, R.; Cochonneau, G.; Vauchel, P.; Moquet, J.-S.; Baby, P.; Espinoza, J.-C.; Lavado, W.; Carranza, J.; Guyot, J.-L.

    2015-03-01

    Formation of mountain ranges results from complex coupling between lithospheric deformation, mechanisms linked to subduction and surface processes: weathering, erosion, and climate. Today, erosion of the eastern Andean cordillera and sub-Andean foothills supplies over 99% of the sediment load passing through the Amazon Basin. Denudation rates in the upper Ucayali basin are rapid, favoured by a marked seasonality in this region and extreme precipitation cells above sedimentary strata, uplifted during Neogene times by a still active sub-Andean tectonic thrust. Around 40% of those sediments are trapped in the Ucayali retro-foreland basin system. Recent advances in remote sensing for Amazonian large rivers now allow us to complete the ground hydrological data. In this work, we propose a first estimation of the erosion and sedimentation budget of the Ucayali River catchment, based on spatial and conventional HYBAM Observatory network.

  4. Predicting Polylepis distribution: vulnerable and increasingly important Andean woodlands

    Directory of Open Access Journals (Sweden)

    Brian R. Zutta

    2012-11-01

    Full Text Available Polylepis woodlands are a vital resource for preserving biodiversity and hydrological functions, which will be altered by climate change and challenge the sustainability of local human communities. However, these highaltitude Andean ecosystems are becoming increasingly vulnerable due to anthropogenic pressure including fragmentation, deforestation and the increase in livestock. Predicting the distribution of native woodlands has become increasingly important to counteract the negative effects of climate change through reforestation and conservation. The objective of this study was to develop and analyze the distribution models of two species that form extensive woodlands along the Andes, namely Polylepis sericea and P. weberbaueri. This study utilized the program Maxent, climate and remotely sensed environmental layers at 1 km resolution. The predicted distribution model for P. sericea indicated that the species could be located in a variety of habitats along the Andean Cordillera, while P. weberbaueri was restricted to the high elevations of southern Peru and Bolivia. For both species, elevation and temperature metrics were the most significant factors for predicted distribution. Further model refinement of Polylepis and other Andean species using increasingly available satellite data demonstrate the potential to help define areas of diversity and improve conservation strategies for the Andes.

  5. Utilización de recursos faunísticos y materias primas líticas durante el Holoceno tardío en la cordillera de Chile central: un enfoque integrador desde Caletón Los Queltehues Use of faunal resources and lithic raw materials during the late Holocene in the cordillera of central Chile: an integrative approach from Caletón los Queltehues

    Directory of Open Access Journals (Sweden)

    Rafael Labarca Encina

    2012-07-01

    Full Text Available Este trabajo evalúa, desde una perspectiva tecnológica y conductual, tendencias a largo plazo de cambio y continuidad en las estrategias de aprovechamiento de recursos faunísticos y líticos en contextos de cazadores-recolectores cordilleranos de Chile central. Para esto, tomamos los datos procedentes de un contexto ubicado en la cuenca superior del río Maipo: Caletón Los Queltehues, y escogimos, de su secuencia ocupacional, los componentes Arcaico IV y Alfarero temprano (5000 a 1000 AP. Los resultados de los análisis no arrojaron mayores variaciones entre ambos períodos en términos de taxones explotados, frecuencia de partes esqueletarias, modificaciones culturales y fragmentación de los restos óseos. De manera similar, las materias primas, las categorías morfofuncionales y los tipos de desechos líticos se observaron relativamente constantes. Sólo se registraron cambios en la tasa de la depositación, la frecuencia de modificaciones naturales y la diversidad de actividades de uso/descarte lítico, las que son interpretadas como una tendencia hacia una variación en la recurrencia e intensidad de la ocupación, pero no en cuanto a su funcionalidad.This article evaluates long-term trends in change and continuity of lithic and faunal use strategies in hunter-gatherer contexts in the central Chilean cordillera from technological and behavioral perspectives. The main objective of the analysis is to articulate both lines of evidence from a behavioral and technological perspective in order to infer unknown elements of the function and organization of activities in this kind of archaeological context. As an initial example, the Archaic IV and Early Ceramic (5000-1000 BP components from a classic site located in the upper valley of the Maipo river, Caletón Los Queltehues, were analyzed in detail. The results do not show significant variation between the periods in exploited taxa, skeletal part frequencies, cultural modifications, or

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

    Science.gov (United States)

    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.

  7. Qochas on Andean highlands

    CERN Document Server

    Sparavigna, Amelia Carolina

    2011-01-01

    On the Andean highlands, the "qochas" are lakes or ponds of natural or artificial origin. An ancient agricultural technique is based on their use. Linked together by a network of canals, qochas form a system of water and soil management, alternately used for crops or pasture. The concave structure of qochas controls the strong evaporation produced by solar radiation and wind blowing. Qochas can be observed in the satellite imagery of Google Maps.

  8. Birds of Two Oceans? Trans-Andean and Divergent Migration of Black Skimmers (Rynchops niger cinerascens) from the Peruvian Amazon

    OpenAIRE

    Lisa C Davenport; Goodenough, Katharine S.; Haugaasen, Torbjørn

    2016-01-01

    Seasonal flooding compels some birds that breed in aquatic habitats in Amazonia to undertake annual migrations, yet we know little about how the complex landscape of the Amazon region is used seasonally by these species. The possibility of trans-Andes migration for Amazonian breeding birds has largely been discounted given the high geographic barrier posed by the Andean Cordillera and the desert habitat along much of the Pacific Coast. Here we demonstrate a trans-Andes route for Black Skimmer...

  9. Sr-Nd isotope changes of late cretaceous to early miocene volcanic rocks in central Chile (33oS)

    International Nuclear Information System (INIS)

    A longitudinal depression, the Central Valley, separates the Coast Range from the Andean Cordillera in central Chile. It contains volcanic and volcaniclastic rocks of Late Cretaceous to Tertiary age deposited in a continental environment, and partly eroded Tertiary volcanic complexes. The age of the rocks at the northern end of the Central Valley and their grouping in formations have been a long-standing controversy in Chilean geology (Thomas, 1958; Aguirre, 1960; Drake et al., 1976; Vergara and Drake, 1979; Thiele, 1980; Moscoso et al., 1982; Gana and Wall, 1997; Lopez-Escobar and Vergara, 1997; Selles, 1999). Here, we report new 40Ar/39Ar data and Sr-Nd isotope ratios for lavas, pyroclastic flows and associated subvolcanic rocks from this part of central Chile (au)

  10. Nazca plate subduction, mantle flow and Cordilleras formation

    Science.gov (United States)

    Capitanio, Fabio A.

    2013-04-01

    The Nazca-South America convergence represents a unique natural laboratory to probe our understanding of subduction, mantle flow and stress coupling at Andean-type margins. Here, it is shown that the most fundamental balance of forces associated with the downgoing slab, the upper plates and the mantle can account for the Nazca plate motions, although it does not adequately explain the variations of the Cordilleran tectonics found along the ~6000 km wide margin. Using three-dimensional numerical models it is shown that trench-parallel gradients in both the driving and resisting forces are an essential component of the force balance, and necessary to reproduce the macroscopic features observed. When along-trench buoyancy variations similar to the Nazca plate's are included, the slab dips and upper plate deformations observed in the Nazca slab, in the Cordilleras and South American continent interiors can be reproduced. The models show that gradients in the resisting shear force along the trench can be as relevant, as they modulate the trench retreat to form the concave Bolivian Orocline. Pressure gradients in the mantle follow the Nazca buoyancy gradients, and effectively rearrange the flow introducing a trench-parallel component, similar to what suggested by seismic anisotropy in this area. Although they introduce only secondary variations to the primary subduction and mantle flow dynamics, the regional features of the Nazca and South American plates exert a primary control at the margin-local scale. This suggests that far-field forces, e.g. from spreading Atlantic or large-scale convection, should play a minor role in the formation of the Cordilleras.

  11. Análisis espectral de materiales geológicos en la Cordillera Volcánica Central de Costa Rica y su relación con la detección remota de anomalías

    Directory of Open Access Journals (Sweden)

    Rejas, J. G.

    2014-12-01

    Full Text Available The aim of this work is the comparative study of methods for calculating spectral anomalies from imaging spectrometry in several test areas of the Central Volcanic Range (CVR of Costa Rica. In the detection of anomalous responses it is assumed no prior knowledge of the targets, so that the pixels are automatically separated according to their spectral information significantly differentiated with respect to a background to be estimated, either globally for the full scene, either locally by image segmentation techniques. We used spectral ranges of visible-near infrared (VNIR, shortwave infrared (SWIR and thermal (TIR data cubes hiperepectrales from HyMAP airborne sensors and MASTER. We have designed experiments on natural scenes of the CVC, and semi-urban of different complexity, analyzing the behavior of the standard RX (Reed & Xiaoli, 1990 anomaly detector and different approaches based on imaging and dimensionality reduction. In this paper we propose a new technique for anomaly detection in hyperspectral data called DAFT (Detector de Anomalías de Fondo Térmico, as a Projection Pursuit (Malpica et al., 2008 variant, based on dimensionality reduction by projecting anomalies or targets with unknown spectral signature to the background, in a range thermal spectrum wavelengths. We discuss the results considering their implications on geological processes, as well as their use as terrestrial analogs for planetary exploration.El objetivo del presente trabajo es el estudio de bandas de absorción y reflexión de espectros de materiales geológicos presentes en distintas áreas de test de la Cordillera Volcánica Central (CVC de Costa Rica, y su correlación con el cálculo automático de anomalías a partir de espectrometría de imagen de alta resolución, también llamada teledetección hiperespectral. En la detección de respuestas anómalas se asume un no conocimiento previo de los objetivos. Los píxeles se separan automáticamente en funci

  12. Andean uplift promotes lowland speciation through vicariance and dispersal in Dendrocincla woodcreepers.

    Science.gov (United States)

    Weir, Jason T; Price, Momoko

    2011-11-01

    Andean uplift contributed importantly to the build-up of high Neotropical diversity. Final uplift of the Eastern Cordillera of Colombia separated once-contiguous lowland faunas east and west of the Andes between 5 and 3.5 million years ago (Ma hereafter). We used DNA sequences from several moderate- to fast-evolving mitochondrial and two slow-evolving nuclear genes to generate a well-supported phylogeny of Dendrocincla woodcreepers, a genus with multiple species endemic to lowland regions both east and west of the Andes. A time-calibrated phylogeny and dispersal-vicariance analysis indicated that uplift of the Eastern Cordillera of Colombia resulted in the initial vicariant separation of a widespread lowland form east and west of the Andes at c. 3.6 Ma. This was followed by two separate east-to-west dispersal events over or around the completed Andes, each producing a genetically distinct lineage. Our analysis suggests that Andean uplift promoted the build-up of biodiversity in lowland Neotropical faunas both through vicariance-based speciation during uplift and through dispersal-based speciation following uplift. In contrast to the multiple colonizations of the trans-Andean region by Dendrocincla, the Atlantic Forest was colonized from the Amazon only once, followed by in situ diversification.

  13. Liolaemus carlosgarini and Liolaemus riodamas (Squamata: Liolaemidae), two new species of lizards lacking precloacal pores, from Andean areas of central Chile.

    Science.gov (United States)

    Esquerré, Damien; Núñez, Herman; Scolaro, José Alejandro

    2013-01-01

    Most of the lizards of the Liolaemus genus present precloacal pores in males, with few exceptions in species of the lineomaculatus and neuquensis groups, and in the elongatus-kriegi complex. The elongatus-kriegi complex, belonging to the Liolaemus (sensu stricto) subgenus, is composed of medium sized, saxicolous, viviparous and insectivorous or omnivorous lizards, distributed between the Andean and Patagonian zones of Chile and Argentina. We reviewed the taxonomic history of this group, and we describe two new species, Liolaemus carlosgarini, found in the vicinity of the Maule Lagoon, in the Maule Region, Chile, and Liolaemus riodamas, described from the population that was originally designated as Liolaemus cf ceii, from Las Damas River, near the Termas del Flaco locality, in the Libertador Bernardo O'Higgins Region, thereby based on this research L. ceii is eliminated from the species belonging to Chile. Both species have as a diagnostic character the absence of precloacal pores, and we suggest here their presumptive systematic relationships in Liolaemus. We analyzed ten species of Liolaemus, in order to perform a phylogenetic analysis based on external morphology, using mostly squamation and morphometric characters. The analysis was performed using PAUP, with the Maximum Parsimony criterion. In addition, through diaphanisation, we studied and described the osteology of the new species. We conclude that species lacking precloacal pores do not form a monophyletic group, and that constructing a phylogeny using only external morphology, at least for this group of reptiles, is insufficient to establish solid phyletic relationships. Other sort of characters should complement the morphological ones. PMID:26131484

  14. Andean region study

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-10-01

    New opportunities for climate change mitigation arising from a higher energy integration among Andean Pact nations were analysed within the framework of the UNEP/GEF Project. Apart from the search for regional mitigation actions, the study was mainly aimed at detecting methodological problems which arise when passing from a strictly national view to the co-ordination of regional actions to deal with climate change. In accordance with the available resources and data, and in view of the mainly methodological nature of the project, it was decided to analyse the opportunities to delve into the energy integration of the Region as regards electricity and natural gas industries and their eventual impact on the emission of greenhouse gases. Although possibilities of setting up electricity and natural gas markets are real, their impacts on GHG emission from the energy system would not prove substantially higher than those which the nations could achieve through the use of their own energy resources, in view that the Andean systems are competitive rather than complementary. More in-depth studies and detail information will be required - unavailable for the present study - to be able to properly evaluate all benefits associated with higher energy integration. Nevertheless, the supply of natural gas to Ecuador seems to be the alternative with the highest impact on GHG emission. If we were to analyse the supply and final consumption of energy jointly, we would most certainly detect additional mitigation options resulting from higher co-operation and co-ordination in the energy field. (EHS)

  15. Cretaceous Exhumation of the North American Cordillera Measured through Mineral Multi-Dating: Insights into Basin Filling Models and Orogenic Architecture

    Science.gov (United States)

    Painter, C. S.; Carrapa, B.; DeCelles, P. G.; Gehrels, G. E.; Thomson, S. N.

    2015-12-01

    exhumation rates is observed in South America in the central Andean arc, Puna-Altiplano, and eastern Cordillera zones.

  16. Drainage reorganization during mountain building in the river system of the Eastern Cordillera of the Colombian Andes

    Science.gov (United States)

    Struth, Lucía; Babault, Julien; Teixell, Antonio

    2015-12-01

    The Eastern Cordillera of Colombia is a thick-skinned thrust-fold belt that is characterized by two topographic domains: (1) the axial zone, a high altitude plateau (the Sabana de Bogotá, 2500 masl) with low local relief and dominated by longitudinal rivers, and (2) the Cordillera flanks, where local relief exceeds 1000 m and transverse rivers dominate. On the basis of an analysis of digital topography and river parameters combined with a review of paleodrainage data, we show that the accumulation of shortening and crustal thickening during the Andean orogeny triggered a process of fluvial reorganization in the Cordillera. Owing to a progressive increase of the regional slope, the drainage network evolves from longitudinal to transverse-dominated, a process that is still active at present. This study provides the idea of progressive divide migration toward the inner part of the mountain belt, by which the area of the Sabana de Bogotá plateau is decreasing, the flanks increase in area, and ultimately transverse rivers will probably dominate the drainage of the Cordillera.

  17. The Andean Geotrail (2): An educational project

    Science.gov (United States)

    Galland, O.; Sassier, C.; Vial, M.; Thiberge, P.

    2009-12-01

    The role of Geosciences in our society is of primary importance. Its implications for humanity relate to major challenges such as climate change, managing energy resources, natural hazard mitigation, and water scarcity. Despite these issues being familiar to specialists, this is in general not the case for the public. In a world, where the impact of human activity is beginning to be seen on the environment, knowledge of the Earth and its history is paramount to make informed decisions that will influence our future. The necessity to educate the global population and raise awareness of Geosciences has led UNESCO to designate 2009 the International Year of the Planet Earth. In the framework of the UNESCO International Year of Planet Earth, we performed an educational project in collaboration with primary, secondary and high schools in France and Norway. Geosciences are not usually studied in schools, but this project allowed more than 600 pupils (from 17 schools) aged 8 to 18 years old to share the geological discoveries of our popular science adventure The Andean Geotrail (see Sassier et al., this session). The main educational goal was to promote Geosciences by illustrating in the field what geology is. Our natural laboratory was the spectacular Andean Cordillera. The secondary goal was to promote careers in geology and highlight their variety by allowing the pupils to meet geologists through portraits of geologists. The teachers of the partner schools used our project as a dynamic complement to their theoretical lessons. To set up this partnership, we obtained the support of the pedagogic supervisors of the French Ministry of National Education. The pedagogical project consisted of three steps: (1) Before the expedition (Oct.-Nov. 2008), we visited the pupils of each partner school to present the project, establish personal contact and engage the pupils in our adventure. (2) During The Andean Geotrail itself (Nov. 2008-Aug. 2009), we continuously documented our

  18. Niche shifts and range expansions along cordilleras drove diversification in a high-elevation endemic plant genus in the tropical Andes.

    Science.gov (United States)

    Kolář, Filip; Dušková, Eva; Sklenář, Petr

    2016-09-01

    The tropical Andes represent one of the world's biodiversity hot spots, but the evolutionary drivers generating their striking species diversity still remain poorly understood. In the treeless high-elevation Andean environments, Pleistocene glacial oscillations and niche differentiation are frequently hypothesized diversification mechanisms; however, sufficiently densely sampled population genetic data supporting this are still lacking. Here, we reconstruct the evolutionary history of Loricaria (Asteraceae), a plant genus endemic to the Andean treeless alpine zone, based on comprehensive population-level sampling of 289 individuals from 67 populations across the entire distribution ranges of its northern Andean species. Partly incongruent AFLP and plastid DNA markers reveal that the distinct genetic structure was shaped by a complex interplay of biogeography (spread along and across the cordilleras), history (Pleistocene glacial oscillations) and local ecological conditions. While plastid variation documents an early split or colonization of the northern Andes by at least two lineages, one of which further diversified, a major split in the AFLP data correlate with altitudinal ecological differentiation. This suggests that niche shifts may be important drivers of Andean diversification not only in forest-alpine transitions, but also within the treeless alpine zone itself. The patterns of genetic differentiation at the intraspecific level reject the hypothesized separation in spatially isolated cordilleras and instead suggest extensive gene flow among populations from distinct mountain chains. Our study highlights that leveraging highly variable markers against extensive population-level sampling is a promising approach to address mechanisms of rapid species diversifications.

  19. 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

  20. A distinctive new subspecies of Scytalopus griseicollis (Aves, Passeriformes, Rhinocryptidae from the northern Eastern Cordillera of Colombia and Venezuela

    Directory of Open Access Journals (Sweden)

    Jorge Avendaño

    2015-06-01

    Full Text Available We describe a new subspecies of Pale-bellied Tapaculo Scytalopus griseicollis from the northern Eastern Cordillera of Colombia and Venezuela. This form differs diagnosably in plumage from described subspecies S. g. griseicollis and S. g. gilesi and from the latter in tail length. It is also differentiated non-diagnosably in voice from both these populations. Ecological niche modelling analysis suggests that the new subspecies is restricted to the Andean montane forest and páramo north of both the arid Chicamocha valley and the Sierra Nevada del Cocuy.

  1. A distinctive new subspecies of Scytalopusgriseicollis (Aves, Passeriformes, Rhinocryptidae) from the northern Eastern Cordillera of Colombia and Venezuela.

    Science.gov (United States)

    Avendaño, Jorge Enrique; Donegan, Thomas M

    2015-01-01

    We describe a new subspecies of Pale-bellied Tapaculo Scytalopusgriseicollis from the northern Eastern Cordillera of Colombia and Venezuela. This form differs diagnosably in plumage from described subspecies Scytalopusgriseicollisgriseicollis and Scytalopusgriseicollisgilesi and from the latter in tail length. It is also differentiated non-diagnosably in voice from both these populations. Ecological niche modelling analysis suggests that the new subspecies is restricted to the Andean montane forest and páramo north of both the arid Chicamocha valley and the Sierra Nevada del Cocuy. PMID:26085800

  2. The Andean Geotrail (1): A scientific adventure

    Science.gov (United States)

    Sassier, C.; Galland, O.; Raufaste, C.; Mair, K.

    2009-12-01

    The role of Geosciences in our society is of primary importance. Its implications for humanity relate to major challenges such as climate change, managing energy resources, natural hazard mitigation, and water scarcity. Despite these issues being familiar to specialists, this is in general not the case for the public. In a world, where the impact of human activity is beginning to be seen on the environment, knowledge of the Earth and its history is paramount to make informed decisions that will influence our future. The necessity to educate the global population and raise awareness of Geosciences has led UNESCO to designate 2009 the International Year of the Planet Earth. In this context and with the label of the UNESCO, we organized and performed a popular science adventure that was followed in real time by both school children and many adults around the world. The Andean Geotrail consisted of a cycling expedition through a spectacular geological environment, the Andean Cordillera. During the nine month expedition, we cycled 8000 km and walked 400 km from Ushuaia in the Southern tip of Argentina to Nazca in Peru to encounter a rich variety of geological environments: active volcanoes, earthquakes, mineral and hydrocarbon deposits, and fantastic geological scenery. All this makes the Andes a great pedagogical natural laboratory. During the expedition, we visited spectacular geological localities that illustrate key Earth Science phenomena (such as mines and hydrocarbon deposits, erupting volcanoes and seismogenically active areas, and national parks) and discovered their implications for the local people. Along the way, we interviewed local geologists and scientists who helped us understand the geology of their areas. We gathered our own observations with those of the local specialists and published essays, articles and photographs on our website and blog (www.georouteandine.fr/English, http://georouteandine.blogspot.com). Seventeen schools in France and Norway

  3. Latitudinal variations (18°-23°S) in denudation rates of western Andean Syntaxis, Chile, South America.

    Science.gov (United States)

    Starke, Jessica; Ehlers, Todd A.; Schaller, Mirjam

    2016-04-01

    Keywords: Cosmogenic nuclides, denudation rates, channel steepness, Chi, syntax, North Chile, South Peru Syntaxial regions of orogens (e.g. the western and eastern Himalayan Syntaxes, St. Elias Mountains Alaska) are regions where curved segments of subducting plates meet and the subducting plate is bent forms a rigid indentor. Previous studies of syntaxial regions in the Himalaya and Alaska document localized and rapid deformation and denudation due to vigorous fluvial or glacial erosional processes. In this study we investigate denudation around an arid end-member syntaxial orogen in South America to understand the interactions between climate and tectonic processes in localizing denudation. We present 35 new cosmogenic 10Be analyses of river sediments to quantify spatial variations in erosion along the Andean Coastal Cordillera and Western Cordillera. The sizes of the drainage basin vary from 5 - 5000 square kilometers. These measurements are linked to analysis of digital topography, variations in fluvial steepness indices and Chi- plots. Cosmogenic derived denudation rates range from 2.5 - 130 mm/kyr. Denudation rates decrease generally from the syntaxis (near Arica, Chile) towards the south (near Antofagasta, Chile) and from the Western Cordillera to the Coastal Cordillera. Topographic analysis of channel steepness variations and Chi-plots also document spatial variations in fluvial erosion and are consistent with spatial pattern in cosmogenic derived denudation rates. In summary the results document both a north to south and east to west variation in denudation around the western Andean margin. The spatial pattern of denudation is consistent with recently proposed patterns of syntaxial deformation driven by the geometry of the bent subducting plate. Denudation rates are also likely influenced to a lesser degree by a latitudinal variation in climate along the Andean margin.

  4. Nueva especie de rana (atelopus) de los farallones de cali, cordillera occidental de colombia

    OpenAIRE

    Kattan, Gustavo

    2012-01-01

    Durante la realización de colecciones herpetológicas en el Departamento del Valle del Cauca, fue encontrada una especie no descrita de Atelopus (Anura: Bufonidae) en los farallones de Cali, a 2600 m de altura. Esta es la primera especie en este género que se encuentra a elevaciones superiores a 2000 m en la Cordillera Occidental. Se conocen varias especies de Atelopus en las Cordilleras Central y Oriental de Colombia y en los Andes ecuatorianos (COCHRAN y GOIN 1970; PETERS 1973; RIVERO 1963) ...

  5. 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

    Jamie Ryan, Kevin M. Ward, Ryan Porter, Susan Beck, George Zandt, Lara Wagner, Estela Minaya, and Hernando Tavera The University of Arizona The University of North Carolina San Calixto Observatorio, La Paz, Bolivia IGP, Lima, Peru In order to investigate the interplay between crustal shortening, lithospheric removal, and surface uplift we have deployed 50 broadband seismometers in northwestern Bolivia and southern Peru as part of the interdisciplinary Central Andean Uplift and Geodynamics of High Topography (CAUGHT) project. The morphotectonic units of the central Andes from west to east, consist of the Western Cordillera, the active volcanic arc, the Altiplano, an internally drained basin (~4 km elevation), the Eastern Cordillera, the high peaks (~6 km elevation) of an older fold and thrust belt, the Subandean zone, the lower elevation active fold and thrust belt, and the foreland Beni basin. Between northwestern Bolivia and southern Peru, the Altiplano pinches out north of Lake Titicaca as the Andes narrow northward. The CAUGHT seismic instruments were deployed between 13° to 18° S latitudes to investigate the crust and mantle lithosphere of the central Andes in this transitional zone. In northwest Bolivia, perpendicular to the strike of the Andes, there is a total of 275 km of documented upper crustal shortening (15° to 17°S) (McQuarrie et al, 2008). Associated with the shortening is crustal thickening and possibly lithospheric removal as the thickening lithospheric root becomes unstable. An important first order study is to compare upper crustal shortening estimates with present day crustal thickness. To estimate crustal thickness, we have calculated receiver functions using an iterative deconvolution method and used common conversion point stacking along the same profile as the geologically based shortening estimates. In our preliminary results, we observed a strong P to S conversion corresponding to the Moho at approximately 60-65 km depth underneath the

  6. 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.

  7. Mountain building at ocean-continent margins - linking mass flux, mechanics, and earthquakes at the Andean margin

    Science.gov (United States)

    Oncken, O.

    2015-12-01

    Deformation at convergent plate boundaries involves various styles of mass flux and of backarc shortening. For the Andes, patterns appear obvious. Long-term mass flux style - i.e. accretionary versus erosive - shows a distinct relationship with forearc as well as backarc deformation mode. Neogene surface deformation exhibits tectonically uplifting areas along the coast driven by interseismically active reverse faulting. Moreover, seismic-cycle vertical displacement is not coincident with long-term vertical motion that probably is superseded by slow basal underplating (southern Chile) or tectonic erosion (northern Chile). Reconstruction clearly indicates that the Central Andean trench has always been underfilled with less than 500 m of sediment. In southern Chile, our data illustrate a similar trend during most of the Cenozoic with a shift around some 6-7 Ma to substantial sediment influx from glaciation of the Patagonian part of the Andean Cordillera. As a consequence, backarc shortening stopped at this latitude, while shortening velocity in the Central Andes was still accelerating. Using latitudinal evolution and variations of shortening rate, orogenic strain accumulation and deformation partitioning in the Andes can be shown to be dominated by distinct factors. The Altiplano-Puna plateaux are characterized by a complete cycle of initial lateral spreading of deformation followed by subsequent localization and acceleration of bulk shortening rate. Estimates of strength evolution based on force balance calculations and critical wedge analysis suggest significant backarc weakening driving this change. Lithosphere-scale failure from strain weakening beyond a critical strain threshold (c. 20%) and fault coalescence with formation of a weak detachment in shales (μeff < 0.1) played a key role in the evolution of the Central Andes. Strain-related lithosphere weakening dominated over the impact of external forcing mechanisms, such as variations of plate convergence

  8. Late Cenozoic calc-alkaline volcanism over the Payenia shallow subduction zone, South-Central Andean back-arc (34°30‧-37°S), Argentina

    Science.gov (United States)

    Litvak, Vanesa D.; Spagnuolo, Mauro G.; Folguera, Andrés; Poma, Stella; Jones, Rosemary E.; Ramos, Víctor A.

    2015-12-01

    A series of mesosilicic volcanic centers have been studied on the San Rafael Block (SRB), 300 km to the east of the present-day volcanic arc. K-Ar ages indicate that this magmatic activity was developed in at least two stages: the older volcanic centers (˜15-10 Ma) are located in the central and westernmost part of the SRB (around 36°S and 69°W) and the younger centers (8-3.5 Ma) are located in an eastern position (around 36°S and 69°30‧W) with respect to the older group. These volcanic rocks have andesitic to dacitic compositions and correspond to a high-K calc-alkaline sequence as shown by their SiO2, K2O and FeO/MgO contents. Elevated Ba/La, Ba/Ta and La/Ta ratios show an arc-like signature, and primitive mantle normalized trace element diagrams show typical depletions of high field strength elements (HFSE) relative to large ion lithophile elements (LILE). Rare earth element (REE) patterns suggest pyroxene and amphibole crystallization. Geochemical data obtained for SRB volcanic rocks support the proposal for a shallow subduction zone for the latest Miocene between 34°30″-37°S. Regionally, SRB volcanism is associated with a mid-Miocene to early Pliocene eastward arc migration caused by the shallowing of the subducting slab in the South-Central Andes at these latitudes, which represents the evolution of the Payenia shallow subduction segment. Overall, middle Miocene to early Pliocene volcanism located in the Payenia back-arc shows evidence for the influence of slab-related components. The younger (8-3.5 Ma) San Rafael volcanic rocks indicate the maximum slab shallowing and the easternmost extent of slab influence in the back-arc.

  9. The role of crustal and eruptive processes versus source variations in controlling the oxidation state of iron in Central Andean magmas

    Science.gov (United States)

    Grocke, Stephanie B.; Cottrell, Elizabeth; de Silva, Shanaka; Kelley, Katherine A.

    2016-04-01

    The composition of the continental crust is closely tied to subduction zone magmatism. Elevated oxygen fugacity (fO2) plays a central role in fostering crystallization of oxide minerals and thereby aids in generating the calc-alkaline trend of iron depletion that characterizes the continents. Along continental margins, arc magmas erupt through continental crust and often undergo extensive differentiation that may modify magmatic fO2. The importance of the subducting slab and mantle wedge relative to the effects of this differentiation on the fO2 recorded by continental arc magmas remains relatively unconstrained. Here, we focus on the effect of differentiation on magmatic fO2 using a suite of 14 samples from the Central Volcanic Zone (CVZ) of the Andes where the continental crust is atypically thick (60-80 km). The samples range in composition from ∼55 to 74 wt% SiO2 and represent the Neogene history of the arc. Samples are basaltic andesite to rhyolite and span a range of radiogenic isotopic compositions (87Sr/86Sr = ∼0.705-0.712) that represent 30 to 100% crustal assimilation. We use several proxies to estimate the fO2 recorded by lavas, pumice, and scoria: (1) whole rock Fe3+ / Σ Fe ratios, (2) Fe3+ / Σ Fe ratios in quartz-hosted melt inclusions, and (3) Fe-Ti oxide oxygen-barometry. Comparison of the fO2 calculated from bulk Fe3+ / Σ Fe ratios (post-eruptive) with that derived from Fe-Ti oxides or melt inclusion Fe3+ / Σ Fe ratios (pre-eruptive), enables us to quantify the effect of syn- or post-eruptive alteration, and to select rocks for bulk analysis appropriate for the determination of pre-eruptive magmatic fO2 using a strict criterion developed here. Across our sample suite, and in context with samples from the literature, we do not find evidence for systematic oxidation due to crystal fractionation or crustal contamination. Less evolved samples, ranging from 55 to 61 wt% SiO2, record a range of >3 orders of magnitude in fO2, spanning the fO2 range

  10. New isotopic ages and the timing of orogenic events in the Cordillera Darwin, southernmost Chilean Andes

    Science.gov (United States)

    Hervé, F.; Nelson, E.; Kawashita, K.; Suárez, M.

    1981-10-01

    The Cordillera Darwin, a structural culmination in the Andes of Tierra del Fuego, exposes an orogenic core zone that has undergone polyphase deformation and metamorphism. Some of the classic problems of orogenic zones have remained unanswered in the Cordillera Darwin: the age of deformed plutonic rocks, the distinction of structurally reactivated basement and metamorphosed cover rocks, and the timing of orogenic events. This study addresses and partially answers these questions. A well-constrained Rb-Sr isochron age of157±8m.y. and an initial 87Sr/ 86Sr ratio of 0.7087 obtained from a pre-tectonic granitic suite suggest a genetic relation between this suite and Upper Jurassic silicic volcanic rocks in the cover sequence (Tobifera Formation), and also suggest involvement of continental crust in formation of these magmas. A poorly constrained Rb-Sr isochron age of240±40m.y. obtained from supposed basement schists is consistent with field relations in the area which suggest a late Paleozoic/early Mesozoic metamorphism for these pre-Late Jurassic rocks. However, because of scatter in the data and the uncertainties involved in dating metasedimentary rocks, the significance of the isotopic age is dubious. Compilation of previously published ages in the area [9] with new mineral ages reported here indicate that "early Andean" orogenic events occurred between 100 and 84 m.y. ago, and that subduction-related magmatism has contributed, probably discontinuously, to the crustal evolution of the region throughout the Mesozoic.

  11. New Paleomagnetic Results and Ar-Ar Geochronology From the Vallenar Region (29oS), N. Chile: Implications for the Timing of Rotations in the Andean Forearc Region.

    Science.gov (United States)

    Gipson, M. J.; Taylor, G. K.; Grocott, J.

    2001-12-01

    The Andean forearc in northern Chile comprises from west to east three tectonomorphic zones - the Coastal Cordillera, the Central Valley and the Precordillera/Chilean Altiplano which lie outboard of the High Andes which represent the present-day active magmatic/volcanic arc. In the Vallenar region the Coastal Cordillera passes directly eastward into the Precordillera with no Central Valley present. The Coastal Cordillera is composed of deformed Palaeozoic sediments intruded by Permo-Triassic plutons, which together comprise the basement of the region. This basement is intruded by Jurassic to Upper Cretaceous plutons of the Coastal Batholith, which is in part overlain by and intruded into Lower Cretaceous arc to back-arc sequences of volcanics and marine limestones. This region is separated from the Upper Cretaceous and Lower Tertiary volcanics and intrusives of the Precordillera to the east by a narrow deformational zone which extends for at least 200km along strike and which we believe to have formed as a result of sinistral transpression. New palaeomagnetic results from the westernmost part of the Lower Cretaceous batholith (n = 7/9 sites, dec = 35.5, inc = -45.0, {α }95 = 4.9), dated to between 130-128 Ma using Ar-Ar geochronology, reveal a well constrained clockwise rotation of 47 {+/-} 7o, consistent with previous results from further north in the Coastal Cordillera. Results from the easternmost pluton of the batholith, dated at 91 Ma, yields a characteristic direction (n = 9 sites, dec = 22.6, inc = -51.1, {α }95 = 4.5) and a rotation of 37 {+/-} 7o. The Coastal Cordillera - Precordillera boundary in this region is marked by an interbedded sequence of red sandstones and andesitic flows (the Punte del Cobre Fm.) overlain by limestones (Chanarcillo Gp.) which are here deformed in a relatively narrow (5-10km wide) fold and thrust belt. The characteristic magnetization of these units (n = 9 sites, dec = 31.5, inc = -50.7, α 95 = 4.3) clearly fails the fold

  12. The intersection of climate, tectonic uplift, and regional groundwater flow in the central Andean Plateau: Insight from the accumulation of the massive evaporite deposit in the Salar de Atacama, Chile

    Science.gov (United States)

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

    2015-12-01

    The Salar de Atacama (SdA), a large endorheic basin adjacent to the Central Andes in the hyperarid Atacama Desert, has accumulated over 1800 km3 of evaporites and a lithium-rich brine since the late Miocene. Focused groundwater discharge in endorheic basins, such as those in the Chilean Altiplano, provide opportunities to investigate mechanisms for closing hydrologic budgets in arid regions. We demonstrate that modern evapotranspiration is 5 to 21 times greater than modern recharge from precipitation in the topographic watershed. Multiple lines of evidence including an adapted chloride mass balance method applied to remotely sensed precipitation estimates and sodium mass balance calculations support this conclusion. We contend that the missing water needed to close the extreme hydrologic imbalance of SdA is sourced from recharge on the orogenic plateau in an area over 4 times larger than the topographic watershed, augmented by transient draining of stored groundwater. Groundwater recharged during wetter periods in the late Pleistocene is still actively draining and discharging from storage without corresponding recharge into the system. Geologic evidence from the volume of evaporites deposited in the basin suggests that the SdA has been receiving significant amounts of fresh inflow waters over at least 7 Ma despite the region being hyperarid over the same time frame. Our conceptualization of the depositional model for evaporite accumulation necessitates the water table being at or close to the land surface. Subsidence associated with basin development has accommodated significant accumulation of these deposits thereby requiring the sustenance of fresh inflow waters during uplift of the Andean plateau. Sustained groundwater discharge to the basin requires long residence times, deep water tables and strong gradients in landscape and climate enabled by an uplifting plateau. The application of steady state assumptions to the modern hydrologic system are unsupported by

  13. Geodynamic controls on the contamination of Cenozoic arc magmas in the southern Central Andes: Insights from the O and Hf isotopic composition of zircon

    Science.gov (United States)

    Jones, Rosemary E.; Kirstein, Linda A.; Kasemann, Simone A.; Dhuime, Bruno; Elliott, Tim; Litvak, Vanesa D.; Alonso, Ricardo; Hinton, Richard

    2015-09-01

    Subduction zones, such as the Andean convergent margin of South America, are sites of active continental growth and crustal recycling. The composition of arc magmas, and therefore new continental crust, reflects variable contributions from mantle, crustal and subducted reservoirs. Temporal (Ma) and spatial (km) variations in these contributions to southern Central Andean arc magmas are investigated in relation to the changing plate geometry and geodynamic setting of the southern Central Andes (28-32° S) during the Cenozoic. The in-situ analysis of O and Hf isotopes in zircon, from both intrusive (granitoids) and extrusive (basaltic andesites to rhyolites) Late Cretaceous - Late Miocene arc magmatic rocks, combined with high resolution U-Pb dating, demonstrates distinct across-arc variations. Mantle-like δ18O(zircon) values (+5.4‰ to +5.7‰ (±0.4 (2σ))) and juvenile initial εHf(zircon) values (+8.3 (±0.8 (2σ)) to +10.0 (±0.9 (2σ))), combined with a lack of zircon inheritance suggests that the Late Cretaceous (∼73 Ma) to Eocene (∼39 Ma) granitoids emplaced in the Principal Cordillera of Chile formed from mantle-derived melts with very limited interaction with continental crustal material, therefore representing a sustained period of upper crustal growth. Late Eocene (∼36 Ma) to Early Miocene (∼17 Ma) volcanic arc rocks present in the Frontal Cordillera have 'mantle-like' δ18O(zircon) values (+4.8‰ (±0.2 (2σ) to +5.8‰ (±0.5 (2σ))), but less radiogenic initial εHf(zircon) values (+1.0 (±1.1 (2σ)) to +4.0 (±0.6 (2σ))) providing evidence for mixing of mantle-derived melts with the Late Paleozoic - Early Mesozoic basement (up to ∼20%). The assimilation of both Late Paleozoic - Early Mesozoic Andean crust and a Grenville-aged basement is required to produce the higher than 'mantle-like' δ18O(zircon) values (+5.5‰ (±0.6 (2σ) to +7.2‰ (±0.4 (2σ))) and unradiogenic, initial εHf(zircon) values (-3.9 (±1.0 (2σ)) to +1.6 (±4.4 (2

  14. Cenozoic back-arc magmatism of the southern extra-Andean Patagonia (44° 30' - 52° S: A review of geochemical data and geodynamic interpretations

    Directory of Open Access Journals (Sweden)

    M. D'Orazio

    2004-12-01

    Full Text Available Huge amounts of basaltic s.l. lavas were persistently erupted along the eastern side of the Andean Cordillera, throughout Cenozoic time, forming extensive plateaus, hundreds of monogenetic scoria cones and other volcanic structures in a continental back-arc setting. The igneous products exposed in the southern sector of the extra-Andean Patagonia (44° 30' - 52° S are dominantly mafic with minor slightly evolved compositions and rare highly differentiated products. The many published chemical analyses of these rocks, indicate that the mafic lavas range from strongly silica - undersaturated basanites to oversaturated basaltic andesites, and that most of the lavas have a typical within-plate geochemical signature. However, a number of lavas, generally erupted in the western-central sectors of Patagonia, are characterized by different distributions of the incompatible elements with high LILE/HFSE and LREE/HFSE ratios. The REE distribution modelling suggests a low degree of melting of a deep (> 70 km garnet-bearing source for the alkaline magmas, and a higher degree of melting of the same source, or an even higher degree of melting of an enriched source, for the subalkaline magmas. The available Sr-Nd-Pb isotope compositions clearly attest to a major geographic variation: the southernmost lavas have lower 87Sr/86Sr and higher 143Nd/144Nd and 206Pb/204Pb ratios with respect to those erupted to the north. On the whole, the Sr-Nd-Pb isotope compositions of the southern Patagonia lavas fall within the typical range of within-plate continental magmas; in addition the Pb isotope ratios fall in the range of the Southern Hemisphere Dupal Pb isotope anomaly. The geochemical variations of the southern Patagonia lavas are discussed in terms of different geochemical components: depleted and enriched sub-slab asthenosphere, enriched continental lithospheric mantle, continental crust and subducted materials. The geodynamic significance is interpreted with in the

  15. [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.

  16. Mixed bird flocks: patterns of activity and species composition in a region of the Central Andes of Colombia Bandadas mixtas de aves: patrones de actividad y composición de especies en una región de la Cordillera Central de los Andes de Colombia

    Directory of Open Access Journals (Sweden)

    Enrique Arbeláez-Cortés

    2011-06-01

    Full Text Available Mixed bird flocks are groups of individuals from different species that travel and forage together. Such groups are common in several bird communities around the world. We present species composition and activity patterns of mixed bird flocks in a region of the Central Andes of Colombia. We compared the number of species per flock, as well as the number of flocks among 3 different habitats. We tested hypotheses concerning the flocks daily activity and the co-occurrences of species within them. We recorded 75 species, and the species number per flock varied from 4 to 21. Our data suggest that habitat affects the number of flocks but not their species number, and that the activity of flocks is similar throughout the day. In addition, the association of birds in flocks is affected by interspecific facilitation, with some species co-occurrences found more times than expected by chance. We hypothesize that some tanager species could have a role in flock cohesion. We witnessed 2 predator attacks upon flocks, a number of agonistic interactions among flock members, and squirrels following bird flocks. Our results meet some general patterns described for mixed bird flocks.Las bandadas mixtas de aves son grupos de individuos de diferentes especies que viajan y forrajean juntos, y son comunes en varias comunidades de aves alrededor del mundo. Presentamos la composición de especies y los patrones de actividad de las bandadas mixtas de aves en una región de la Cordillera Central de los Andes Colombianos. Comparamos el número de especies por bandada y el número de bandadas en 3 hábitats distintos. Evaluamos hipótesis relacionadas con la actividad de las bandadas durante el día y la presencia simultánea de especies en estos grupos. Observamos 75 especies, y el número de especies por bandada varió entre 4 y 21. Nuestros datos indican que el hábitat parece afectar el número de bandadas pero no su número de especies y que la actividad de las bandadas

  17. Can cosmic ray exposure dating reveal the normal faulting activity of the Cordillera Blanca Fault, Peru?

    Directory of Open Access Journals (Sweden)

    L.L. Siame

    2006-12-01

    Full Text Available The build-up of in situ-produced cosmogenic 10Be within bedrock scarps and escarpments associated to the Cordillera Blanca Normal Fault, Peru, was measured to evaluate, through Cosmic Ray Exposure dating, its normal faulting activity. The highest mountain peaks in Peru belong to the 210 km-long, NW- striking, Cordillera Blanca. Along its western border, the Cordillera Blanca Normal Fault is responsible for a vertical relief over 4.4 km, whose prominent 2 km high escarpment is characterized by ~1 km-high triangular facets corresponding to vertical displacements cumulated during the last 1-2 million years. At a more detailed scale, this fault system exhibits continuous geomorphic evidence of repeated displacements, underlined by 2 to 70 m-high scarps, corresponding to vertical displacements cumulated since Late Pleistocene and Holocene periods. Although microseismicity occurs along the Cordillera Blanca Normal Fault, no major historical or instrumental earthquake has been recorded since the beginning of the Spanish settlement in the 16th century. To evaluate the vertical slip rate along the major 90 km-long central segment of the Cordillera Blanca Normal Fault, the Quaternary fault escarpment (i.e., triangular facet, as well as the bedrock fault scarp, have been sampled for 10Be Cosmic Ray Exposure dating. Even if the uppermost part of the triangular facets have been resurfaced by the Last Glacial Maximum glaciers, our results allow to estimate a vertical slip-rate of 3±1 mm/yr, and suggest at least 2 seismic events during the last 3000 years.

  18. Late Cenozoic geomorphologic signal of Andean forearc deformation and tilting associated with the uplift and climate changes of the Southern Atacama Desert (26°S 28°S)

    Science.gov (United States)

    Riquelme, Rodrigo; Hérail, Gérard; Martinod, Joseph; Charrier, Reynaldo; Darrozes, José

    2007-05-01

    We analyze remarkable examples of the large (˜ 10,000 km 2) and local-scale (˜ 100 km 2) landscape forms related to Late Cenozoic geomorphologic evolution of the Andean forearc region in the Southern Atacama Desert. We also consider the continental sedimentary deposits, so-called "Atacama Gravels", which are related to the degradation of the landscape during the Neogene. Our analysis integrates 1:50,000 field cartography, Landsat TM images observations, ˜ 1:1000 sedimentary logging data, and 50 m horizontal resolution topographic data to reconstruct the Late Cenozoic geomorphologic evolution of this region and discuss the factors that control it, i.e., Miocene aridification of the climate and Neogene Central Andean uplift. We determine that the Precordillera was already formed in the Oligocene and most of the present-day altitude of the Precordillera was reached before that time. Afterward, five episodes of geomorphologic evolution can be differentiated: (1) the development of an Oligocene deep incised drainage system cutting the uplifted Precordillera (up to 2000 m of vertical incision) and connecting it to the Ocean; followed by (2) the infilling of deep incised valleys by up to 400 m of Atacama Gravels. This infill started in the Early Miocene with the development of fluvial deposition and finished in the Middle Miocene with playa and playa lake depositions. We propose that playa-related deposition occurs in an endorheic context related to tectonic activity of the Atacama Fault System and Coastal Cordillera uplift. However, the upward sedimentologic variation in the Atacama Gravels evidences a progressive aridification of the climate. Subsequently, we have identified the effects of the Middle-Upper Miocene slow tectonic deformation: the Neogene Andean uplift is accommodated by a tilting or flexuring of the inner-forearc (Central Depression and Precordillera) related to some hundreds of meters of uplift in the Precordillera. This tilting or flexuring results

  19. Snakes of an urban-rural landscape in the central Andes of Colombia: species composition, distribution, and natural history

    Directory of Open Access Journals (Sweden)

    Julián Andrés Rojas-Morales

    2012-12-01

    Full Text Available From 2005 to 2011, I studied the composition, distribution and natural history of an Andean urban-rural snake assemblage at the Cordillera Central of Colombia, based on three data sources: (1 examination of specimens in the MHN-UC [Museo de Historia Natural, Universidad de Caldas], (2 incidental encounters by author, and (3 collection of data by other researchers. Additionally, I provide natural history notes for the species involved. A total of 14 species, including two subspecies of snakes, belonging to 12 genera and four families, have been found in the studied area (municipality of Manizales, Caldas. Taking into account this total, 10 had atleast one record in the urban area, 13 in the rural area and 14 in forested areas. Only Liophis epinephelus bimaculatus was found exclusively in forest environment. Three species (21.4% are apparently endemic to the region, six species (42.8% correspond to afauna representative of the Tropical–Andean range of South America, four species (28.5% are distributed from Central America to the tropical Andes, and only one species is widely distributed in the whole continent. The snake assemblage in Manizales is mostly terrestrial, and in general, the species tend to be more active in the rainy periods of the year (mainly from October–December, and most of them may occasionally be found in urban areas, mainly close to areas of vegetation such as crops and pastures.

  20. Andean snowpack since AD 1150 inferred from rainfall, tree-ring and documentary records

    Science.gov (United States)

    The Andean snowpack is the main source of freshwater and arguably the single most important natural resource for the populated, semi-arid regions of central Chile and central-western Argentina. However, apart from recent analyses of instrumental snowpack data, very little is known about the long ter...

  1. VARIABILIDAD ESPACIAL DE PROPIEDADES QUÍMICAS Y FÍSICAS EN UN TYPIC UDIVITRANDS, ARENOSO DE LA REGIÓN ANDINA CENTRAL COLOMBIANA SPATIAL VARIABILITY OF CHEMICAL AND PHYSICAL PROPERTIES OF A SANDY TYPIC UDIVITRANDS IN THE COLOMBIAN CENTRAL ANDEAN ZONE

    Directory of Open Access Journals (Sweden)

    Franco Humberto Obando Moncayo

    2006-06-01

    Full Text Available Se estudió la variabilidad espacial de propiedades químicas y físicas en un Typic Udivitrands arenoso de la granja experimental Tesorito de la Universidad de Caldas, ubicado en la Cordillera Central Colombiana a 5º 01’47” N, 75º 26’ 03” W y 2280 msnm. El área experimental se localiza en un Piedemonte Coluvial, con un manejo antecedente y actual en pastos, frutales de clima frío moderado y hortalizas. Se realizó un muestreo sistemático en red con una distancia aproximada entre sitios de muestreo de 30 m en un área efectiva de 3,96 ha; para un total de 60 sitios. El análisis geoestadístico se llevó a cabo en tres etapas: 1 análisis exploratorio de los datos utilizando los software Statgraphics Plus v 2.0 y SPSS 9.0, 2 análisis estructural o semivariografía. 3 interpolación por el método Kriging puntual utilizando el paquete geoestadístico GS+ versión 5.3b. Los modelos esférico y exponencial fueron los de mejor ajuste a los modelos experimentales excepto para el DPM, que se ajustó a un modelo lineal (Nugget puro. El alcance para las variables analizadas se encuentra dentro de la distancia máxima ( 350 m del área de muestreo considerada para el cálculo de los semivariogramas, excepto para el fósforo que presento un alcance de 479,4 metros. El alcance fluctuó entre 33,9 m para el Na y 308,5 m para el DPM. La variabilidad espacial de atributos del suelo en el predio experimental es alta, siendo mayor en propiedades químicas, igualmente, permitió visualizar la variabilidad espacial del deterioro estructural del suelo coincidiendo con la zona de mayor variabilidad química.A study of the spatial variability of the chemical and physical properties of a Sandy Typic Udivitrands was conducted in the Tesorito Experimental Farm of Universidad de Caldas, located in the Colombian Central Cordillera at 5º 01’47” N, 75º 26’ 03” W and 2280 m elevation. The experimental plot was located in a Coluvial Piedmont with

  2. Regional polyphase deformation of the Eastern Sierras Pampeanas (Argentina Andean foreland): strengths and weaknesses of paleostress inversion

    Science.gov (United States)

    Traforti, Anna; Zampieri, Dario; Massironi, Matteo; Viola, Giulio; Alvarado, Patricia; Di Toro, Giulio

    2016-04-01

    The Eastern Sierras Pampeanas of central Argentina are composed of a series of basement-cored ranges, located in the Andean foreland c. 600 km east of the Andean Cordillera. Although uplift of the ranges is partly attributed to the regional Neogene evolution (Ramos et al. 2002), many questions remain as to the timing and style of deformation. In fact, the Eastern Sierras Pampeanas show compelling evidence of a long lasting brittle history (spanning the Early Carboniferous to Present time), characterised by several deformation events reflecting different tectonic regimes. Each deformation phase resulted in further strain increments accommodated by reactivation of inherited structures and rheological anisotropies (Martino 2003). In the framework of such a polyphase brittle tectonic evolution affecting highly anisotropic basement rocks, the application of paleostress inversion methods, though powerful, suffers from some shortcomings, such as the likely heterogeneous character of fault slip datasets and the possible reactivation of even highly misoriented structures, and thus requires careful analysis. The challenge is to gather sufficient fault-slip data, to develop a proper understanding of the regional evolution. This is done by the identification of internally consistent fault and fracture subsets (associated to distinct stress states on the basis of their geometric and kinematic compatibility) in order to generate a chronologically-constrained evolutionary conceptual model. Based on large fault-slip datasets collected in the Sierras de Cordoba (Eastern Sierras Pampeanas), reduced stress tensors have been generated and interpreted as part of an evolutionary model by considering the obtained results against: (i) existing K-Ar illite ages of fault gouges in the study area (Bense et al. 2013), (ii) the nature and orientation of pre-existing anisotropies and (iii) the present-day stress field due to the convergence of the Nazca and South America plates (main shortening

  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. Proglacial hydrology in the tropical Andes: lessons from the Cordillera Blanca, Peru (Invited)

    Science.gov (United States)

    McKenzie, J. M.; Mark, B. G.; Baraer, M.

    2009-12-01

    Understanding the complexities of tropical Andean hydrology is critical for managing modern water resources and interpreting paleohydrologic records. Glaciers are the most visible component of these systems, responding to global climate change and acting as critical hydrologic reservoirs. Tropical Andean glaciers are undergoing rapid retreat with complex impacts on the downstream hydrology. Groundwater is also an important component of the Andean regional hydrologic system, but its contribution is difficult to assess due to remote site access, minimal baseline data, and lack of continuous historical discharge and precipitation measurements. We have synthesized hydrochemical data from synoptically sampled glacial melt water, groundwater, precipitation, and stream discharge collected intermittently between 1998 and July 2008 throughout the Callejon de Huaylas, a 5000 km2 watershed that drains the western side of the Cordillera Blanca in northern Perú. Our data from 2004 to 2006 show systematic annual shifts in the isotopic ratios (δ18O and δ2H) of river water, indicating an increase in glacial melt water input, and we are able to use these changes across the Cordillera Blanca to estimate an average increase of 1.6 (± 1.1) % in the specific discharge of the glacierized basins. Enhanced total stream discharge in more glacierized catchments (>20% glacier area) is demonstrated by a significant positive trend in a 43-year discharge anomaly record. Our hydrochemical basin characterization method (HBCM) uses chemical mass balance mixing to quantify the contribution of glacial melt water, groundwater, and surface runoff to streams for different valleys and nested watersheds in the Callejon de Huaylas. The Yanamarey basin (7% glaciated) has been observed since 1998 and the HBCM results show good agreement with measured stream discharge (maximum R2 of 0.99) for monthly cumulative values. These results suggest that for most of the studied years groundwater is the main

  5. THE PAIPA VOLCANO, EASTERN CORDILLERA OF COLOMBIA, SOUTH AMERICA (PART II: PETROGRAPHY AND MAJOR ELEMENTS PETROLOGY

    Directory of Open Access Journals (Sweden)

    Cepeda Héctor

    2005-08-01

    Full Text Available Paipa volcano products are mainly pyroclastic pumice and ash flow tuffs, lava domes and pyroclastic block and ash flow tuffs. They are classified as alkaline rhyolites and trachytes and high-K calcalkaline rhyolites. Chemical data show SiO2 values between 68 and 72%, and alkalis (Na2O+K2O content of 7%-10%. Essential minerals are phenocrysts and glomerocrysts of anorthoclase, sanidine up to 1,5 cm and anorthoclase-mantled plagioclase; accessory minerals are red biotite, and hastingsite while trace minerals are augite, zircon, sphene and magnetite. Crystals have disequilibrium textures, such as dissolution embayments, corrosion and reabsortion borders, normal, inverse, oscillating and patchy zonation, together with fibrous borders intercalated with euhedral borders. In correlation with published data of Iza volcanic rocks, Paipa rocks chemical composition confirms that acid and alkaline magmas that have erupted in the Eastern Cordillera of Colombia during the Neogene are strongly different from the calc-alkaline magmas that erupt in the westward active arc (Central Cordillera. Detailed structural, geochemical and geophysical research has to be done in future research to establish the geodynamic framework that governs the volcanism of the Eastern Cordillera.

  6. Disentangling Topographic and Climatic Change during the Late Cretaceous and Cenozoic in the Western US Cordillera

    Science.gov (United States)

    Snell, K. E.; Eiler, J. M.; Wernicke, B. P.; Peppe, D. J.; Fox, D. L.; Fetrow, A. C.; Passey, B. H.

    2014-12-01

    A diverse suite of tectonic and climatic drivers influenced the topographic evolution of the western USA Cordillera. Despite years of study, considerable uncertainty remains about fundamentals of this evolution, such as the timing and magnitude of maximum average elevations for the different physiographic provinces; the drivers and topographic effects of different episodes of extension during the Cenozoic; and the relative relief of peaks and intermontane basins within the Cordillera at different times and in different places. Numerous tectonic models have been developed to explain the evolution of the Cordillera, and understanding these details is key for distinguishing between these different models. In addition, the topographic changes in the Cordillera have important implications for regional and local climate of the western US at different times in the past, and may drive important differences in local climatic responses to global climate changes through the Cenozoic. The majority of the tools that currently exist for quantitatively reconstructing changes in topography through time and space rely on paleoclimate proxy data. Thus it is also important to be able to disentangle climatic change from elevation change in terrestrial paleoclimate records. To address some of these outstanding questions, we have generated and compiled paleotemperature estimates from the Late Cretaceous through the Miocene of the western US. In this presentation, we will focus on the latest installment of the project, which utilizes Oligocene paleotemperature records from central Utah and South Dakota and Miocene-Holocene paleotemperature records from Kansas. The data are dominantly composed of mean annual temperature estimates from leaf margin analysis and summer temperature estimates from carbonate clumped isotope thermometry. We will discuss how these data compare to temperature data from the Paleogene from the western US, what general trends exist within all the data and how these

  7. Trans-Andean Ancistrus (Siluriformes: Loricariidae).

    Science.gov (United States)

    Taphorn, Donald C; Armbruster, Jonathan W; Villa-Navarro, Francisco; Ray, C Keith

    2013-01-01

    We review the trans-Andean species of Ancistrus from Panama, Colombia and Venezuela. Based on analyses of meristic, morphometric and pigmentation pattern data of preserved specimens, eight of sixteen species reported from this region are considered valid and two new species are described. Here we review Ancistrus chagresi Eigenmann & Eigenmann 1889 from both slopes of central Panama; A. centrolepis Regan 1913 from Pacific slopes of eastern Panama and western Colombia; Ancistrus caucanus Fowler 1943, from the Magdalena River drainage in northern Colombia; Ancistrus martini Schultz 1944, from the Lake Maracaibo Basin of Venezuela and Colombia. Ancistrus galani Pérez & Viloria 1994, from a cave in the Lake Maracaibo Basin of Venezuela is considered valid but was not examined. Ancistrus tolima new species is described from the upper Magdalena River drainage and Ancistrus vericaucanus new species is described from the upper Cauca River drainage. Ancistrus gymnorhynchus Kner 1854 and A. falconensis Taphorn, Armbruster & Rodriguez-O. 2010 were treated previously. One specimen of A. clementinae Rendahl 1937 from the Pacific coast of Ecuador was examined, it is considered a valid species. A key for identification and geographical ranges are provided. PMID:26287090

  8. 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

  9. Oligocene-Miocene deformational and depositional history of the Andean hinterland basin in the northern Altiplano plateau, southern Peru

    Science.gov (United States)

    Perez, Nicholas D.; Horton, Brian K.

    2014-09-01

    Cenozoic basin fill of the northern Altiplano plateau records the tectonic development of the flanking Western Cordillera magmatic arc and Eastern Cordillera fold-thrust belt. The Ayaviri hinterland basin of southern Peru contains a ~2300 m thick succession of fluvial sandstones and overbank siltstones (upper Oligocene Puno Group and lower Miocene lower Tinajani Formation) capped by ~400 m of alluvial fan conglomerates (middle Miocene upper Tinajani Formation). New U-Pb zircon chronostratigraphic constraints from ~30 to 15 Ma yield sediment accumulation rates of 110-660 m/Myr. Newly dated growth strata highlight the genetic role played by thrust displacement in basin evolution. A several phase accumulation history derived from chronostratigraphic, provenance, and structural data reveals Oligocene basin filling by fluvial sand and mud that changes provenance from Western Cordillera Mesozoic-Cenozoic volcanic rocks to Paleozoic-Mesozoic Eastern Cordillera sedimentary rocks driven by deformation along the southwest directed, northeastern basin margin Ayaviri thrust at 28-26 Ma. Continued early Miocene fluvial deposition was sourced solely from the Eastern Cordillera. An abrupt middle Miocene shift to coarse alluvial fan deposition sourced from the Western Cordillera was driven by out-of-sequence deformation along the northeast directed, southwestern basin margin Pasani thrust at 18-16 Ma. This northern Altiplano out-of-sequence deformation was coincident with increased Eastern and Western Cordillera exhumation and thrusting and may be symptomatic of changes in critical wedge dynamics. The overall record of basin sedimentation and syndepositional fold-thrust deformation emphasizes the role of regional shortening in governing crustal thickening and basin evolution in the central Andes during the Oligocene to Miocene.

  10. A cosmogenic 10Be chronology for the local last glacial maximum and termination in the Cordillera Oriental, southern Peruvian Andes: Implications for the tropical role in global climate

    Science.gov (United States)

    Bromley, Gordon R. M.; Schaefer, Joerg M.; Hall, Brenda L.; Rademaker, Kurt M.; Putnam, Aaron E.; Todd, Claire E.; Hegland, Matthew; Winckler, Gisela; Jackson, Margaret S.; Strand, Peter D.

    2016-09-01

    Resolving patterns of tropical climate variability during and since the last glacial maximum (LGM) is fundamental to assessing the role of the tropics in global change, both on ice-age and sub-millennial timescales. Here, we present a10Be moraine chronology from the Cordillera Carabaya (14.3°S), a sub-range of the Cordillera Oriental in southern Peru, covering the LGM and the first half of the last glacial termination. Additionally, we recalculate existing 10Be ages using a new tropical high-altitude production rate in order to put our record into broader spatial context. Our results indicate that glaciers deposited a series of moraines during marine isotope stage 2, broadly synchronous with global glacier maxima, but that maximum glacier extent may have occurred prior to stage 2. Thereafter, atmospheric warming drove widespread deglaciation of the Cordillera Carabaya. A subsequent glacier resurgence culminated at ∼16,100 yrs, followed by a second period of glacier recession. Together, the observed deglaciation corresponds to Heinrich Stadial 1 (HS1: ∼18,000-14,600 yrs), during which pluvial lakes on the adjacent Peruvian-Bolivian altiplano rose to their highest levels of the late Pleistocene as a consequence of southward displacement of the inter-tropical convergence zone and intensification of the South American summer monsoon. Deglaciation in the Cordillera Carabaya also coincided with the retreat of higher-latitude mountain glaciers in the Southern Hemisphere. Our findings suggest that HS1 was characterised by atmospheric warming and indicate that deglaciation of the southern Peruvian Andes was driven by rising temperatures, despite increased precipitation. Recalculated 10Be data from other tropical Andean sites support this model. Finally, we suggest that the broadly uniform response during the LGM and termination of the glaciers examined here involved equatorial Pacific sea-surface temperature anomalies and propose a framework for testing the viability

  11. Andean subduction orogeny: feedbacks between tectonics, relief evolution and global climate

    Science.gov (United States)

    Lacassin, Robin; Armijo, Rolando; Coudurier-Curveur, Aurélie; Carrizo, Daniel

    2016-04-01

    The Andean subduction margin, largest tectonic relief on the Earth (13 km vertically from the trench to the Altiplano) has a stepped morphology, which results of the evolution over the past 50 Myr of two parallel flat-ramp thrust systems, at the - previously unidentified - West Andean Thrust (WAT), and at the subduction interface. The evolution of those thrusts appears concomitant with increasing aridity in the Atacama Desert, which keeps a large-scale record of interplaying tectonics and Cenozoic climate change. The coastal morphology is dominated by the Atacama Bench, a giant uplifted terrace at 1-2km asl. Geomorphic and climatic data, numerical experiments of drainage formation are consistent with the development of a flat Atacama morphology close to sea level, interrupted at ≤10 Ma by tectonic uplift prevailing to the present. This suggests recent trench-ward relief growth by incorporation of the coastal Atacama Bench to the Andes reliefs. Thrust splay structures and other complexities above the subduction interface may explain this relief growth, as well as the distribution of asperities under the oceanward forearc, and the down-dip segmentation of coupling and seismicity on the megathrust. Combining those results with geological knowledge at the scale of the whole Central Andes, we show that the Andean orogeny results from protracted processes of bivergent crustal shortening in a wide region squeezed between the rigid Marginal Block and the S America Plate. The overall growth curve of Andean orogeny over the past 50 Myr appears synchronous with the onset of the "ramp-shaped" temperature decrease since the Early Eocene climatic optimum. Andean growth and global cooling may have operated under the same forcing mechanism at plate-scale, involving viscous flow in the mantle. But Andean growth appears modulated by climatic feedbacks causative of stepwise reductions of erosive power over the Andean margin. The first of such events is coeval with Late Eocene

  12. Paleogeographic and tectonic controls on the evolution of Cenozoic basins in the Altiplano and Western Cordillera of southern Peru

    Science.gov (United States)

    Carlotto, Víctor

    2013-03-01

    Integrated studies of stratigraphy, sedimentology, paleogeography and tectonic controls on Cenozoic basins provide the basis for a series of time-slice reconstructions of basin evolution in the Andes of southern Peru. The Altiplano and adjacent margin of the Western Cordillera are characterized by several Paleocene-Miocene synorogenic continental basins with thicknesses locally exceeding 10 km. The evolution of these basins has been controlled by NW-trending tectonic features that mark the Altiplano-Western Cordillera and Altiplano-Eastern Cordillera boundaries and the Condoroma structural high. Sedimentary deposits of Paleocene age preserved in the Altiplano are the result of nonmarine sedimentation in a distal foreland basin. During the early Eocene, predominantly dextral strike-slip movements in the Altiplano between the Cusco-Lagunillas and Urcos-Ayaviri fault systems created the transpressional Kayra basin. The Soncco and Anta basins (middle Eocene-early Oligocene) are related to NE shortening (43-30 Ma) and represent proximal, wedge-top and foredeep basin environments preserved on the Altiplano. At ~ 29-28 Ma, a change to predominantly E-W shortening produced sinistral strike-slip motion along NW-striking faults, resulting in intermontane, transpressional basins. In the Altiplano, the Tinajani and Punacancha (29-5 Ma), and Paruro (12-6 Ma) basins were controlled by the Cusco-Lagunillas and the Urcos-Ayaviri fault systems. The Maure, Tincopalca-Huacochullo and Condoroma basins (22-5 Ma) of the Western Cordillera developed between the Condoroma high and the Cusco-Lagunillas fault system. Oligocene-Miocene sedimentation commonly evolved from proximal (alluvial) facies along the borders to distal (lacustrine) facies. These basins were linked to sinistral strike-slip faults that evolved into reverse-sinistral structures. Plate kinematics may play a role in Andean basin evolution, with deformation influenced by major preexisting faults that dictated paleogeographic

  13. What controls millennial-scale denudation rates across the Central Andes?

    Science.gov (United States)

    Zeilinger, Gerold; Korup, Oliver; Schlunegger, Fritz; Kober, Florian

    2015-04-01

    depends largely on the location within the orogen, causing a strong segmentation reflected by metrics of slope (plane versus cordillera) and precipitation (desert versus tropical rain forest). This regional pattern, contained in larger catchments, is superimposed by a local pattern, revealed in mid- to small-sized catchments. Yet a substantial fraction of the overall variance in denudation rates remains unexplained. We discuss possible reasons for this, and reflect on the prospect of predicting denudation rates in ungauged Central Andean catchments.

  14. Two new Cystoderma species from high Andean Ecuador

    DEFF Research Database (Denmark)

    Saar, I.; Læssøe, Thomas

    2006-01-01

    ABSTRACT: Two new agaric species, Cystoderma andinum and C. papallactae are described from high Andean Ecuador.......ABSTRACT: Two new agaric species, Cystoderma andinum and C. papallactae are described from high Andean Ecuador....

  15. Multi-temporal InSAR for Deformation Monitoring of the Granada and Padul Faults and the Surrounding Area (Betic Cordillera, Southern Spain)

    NARCIS (Netherlands)

    Sousa, J.J.; Ruiz, A.M.; Hooper, A.J.; Hanssen, R.F.; Perski, Z.; Bastos, L.C.; Gil, A.J.; Galindo-Zaldivar, J.; Sanz de Galdeano, C.; Alfaro, P.; Garrido, M.S.; Armenteros, J.A.; Gimenez, E.; Aviles, M.

    2014-01-01

    The quantification of low rate active tectonic structures is a major target of geodetic and geological studies to improve the knowledge of seismic hazards. The central Betic Cordillera (southern Spain) is affected by moderately active tectonic structures and seismicity. Part of this seismic activity

  16. Slope stability of moraines, Cordillera Blanca, Peru

    Science.gov (United States)

    Klimes, J.; Novotny, J.

    2012-12-01

    Landslides originating from inner slopes of moraine dams are often capable of producing glacial lakes outburst floods (GLOFs). Therefore assessing stability conditions of the moraines is important for predicting this potentially damaging phenomenon. Characteristics of the basic mechanical properties of the material and geophysical investigations were applied to collect necessary information for slope stability assessment of the Palcacocha Lake moraine dam, Peru. The lake is situated in the Cordillera Blanca Mts. at the altitude of about 4,500m asl and produced catastrophic GLOF in 1941. Another minor flood originated in 2003 due to landslide impact into the lake. Detailed investigations of this landslide site included geomorphological mapping, geophysical investigations and characterization of basic mechanical properties of the forming material. Geomorphological mapping identified dormant landslide with scarp up to 2m high which developed on the edge of the inner moraine slope. It is conditioned by set of parallel extension trenches which also affected the origin of 2003 landslide. Within its scarp area, significant water bearing layer was noticed around 10 m bellow the moraine surface. Three profiles were investigated using electric resistivity tomography performed on 4poing light instrument with 24 electrodes and with spacing ranging from 1 to 4m. Results helped to verify geometry of the main shear plane of the mapped landslide as well as the spacing and depth of extension trenches. Significant heterogeneity in the moraine resistivity characteristics was found. The high resistivity regions are explained by rock block accumulation whereas the low resistivity may represent wet layers within the moraine body. Grain size distribution of 33 disturbed soil samples originating from moraine material within the Cordillera Blanca Mts., Peru were determined and classified according to the UCSC classification system. The samples were taken from moraine dams and slopes

  17. Changes in vegetation and drainage density as controlling factors in the episodicity of Quaternary sediment flux: southwestern United States and Bolivian Eastern Cordillera

    Science.gov (United States)

    Barnes, J.; Pelletier, J. D.

    2001-12-01

    Piedmont geomorphic surfaces in the southwestern U.S. primarily represent cut-and-fill cycles resulting from variations in sediment supply from adjacent mountain catchments. Although sparse, precise age control supports the hypothesis that sediment supply in the southwestern U.S. can increase by an order of magnitude during Quaternary humid-to-arid transitions recognized in high-resolution paleoclimatic proxies. As an example, this episodicity is quantified with a time series of sediment flux for the central Gila Mountains, southwestern Arizona, where paleosurfaces outcrop in the modern channel bank, permitting an estimate of deposit volume in conjunction with high-resolution photogrammetric DEMs. Age control is provided by a new method of surface exposure dating based on 3D hillslope diffusion adjacent to gullies penetrating the surface. We propose that episodes of piedmont alluviation result from an increase in drainage density resulting from climatically-induced vegetative successions from mature woodland vegetation to desert shrubs that excavate large amounts of hillslope colluvium stored during the previous humid interval. Analogous vegetative shifts occur in the Bolivian Eastern Cordillera (EC). Field observations and analyses of topographic maps and LANDSAT images suggest that the longitudinal profiles of the major rivers of the EC are dominated by an order-of-magnitude increase in Plio-Quaternary hillslope erosion in the elevation zone between approximately 2.5 and 3.5 kilometers above sea level corresponding to glacial-interglacial vegetational successions from Andean forest (glacial) to Paramo grasslands (interglacial). These vegetation changes resulted in rapid fluctuations in drainage density responsible for a large increase in transport rates that alluviated major valleys and enhanced bedrock incision rates downstream. Areas above and below this elevation have perennial grassland and forest, respectively, whose long-term vegetational stability has

  18. Administrative Law in the Andean Community of Nations

    Directory of Open Access Journals (Sweden)

    Jorge Enrique Santos Rodríguez

    2013-12-01

    Full Text Available One of the contemporary tendencies of Administrative Law is the recognition of its existence beyond the borders of a State. Under such premise, this paper aims to demonstrate that in the Andean Community of Nations sufficient elements to consider the existence of an Andean administrative Law. In the Andean statutes and rules, it is possible to identify an administrative function, as well as an administrative organization inside the Andean Integration System; and a system of Andean administrative rules and an administrative justice system.

  19. 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.

  20. Andean highlands: Implications of climate change

    OpenAIRE

    Seth, Anji; Thibeault, J.M.; García, Magali

    2007-01-01

    This presentation provides background on the SANREM CRSP project "Adapting to Change in the Andean Highlands: Practices and Strategies to Address Climate and Market Risks in Vulnerable Agro-Eco Systems" and discusses the means, variability and projections for the Altiplano climate. available in SANREM office, ESIILTRA-4 (Practices and Strategies for Vulnerable Agro-Ecosystems)

  1. Carbon storage and long-term rate of accumulation in high-altitude Andean peatlands of Bolivia

    Directory of Open Access Journals (Sweden)

    J.A. Hribljan

    2015-11-01

    Full Text Available (1 The high-altitude (4,500+ m Andean mountain range of north-western Bolivia contains many peatlands. Despite heavy grazing pressure and potential damage from climate change, little is known about these peatlands. Our objective was to quantify carbon pools, basal ages and long-term peat accumulation rates in peatlands in two areas of the arid puna ecoregion of Bolivia: near the village of Manasaya in the Sajama National Park (Cordillera Occidentale, and in the Tuni Condoriri National Park (Cordillera Real. (2 We cored to 5 m depth in the Manasaya peatland, whose age at 5 m was ca. 3,675 yr. BP with a LARCA of 47 g m-2 yr-1. However, probing indicated that the maximum depth was 7–10 m with a total estimated (by extrapolation carbon stock of 1,040 Mg ha-1. The Tuni peat body was 5.5 m thick and initiated ca. 2,560 cal. yr. BP. The peatland carbon stock was 572 Mg ha-1 with a long-term rate of carbon accumulation (LARCA of 37 g m-2 yr-1. (3 Despite the dry environment of the Bolivian puna, the region contains numerous peatlands with high carbon stocks and rapid carbon accumulation rates. These peatlands are heavily used for llama and alpaca grazing.

  2. Spatial-temporal evolution of topography of the central Andes and implications for deep tectonic processes (Invited)

    Science.gov (United States)

    Garzione, C. N.; Auerbach, D. J.; Bershaw, J. T.; Kar, N.; Smith, J. J.

    2013-12-01

    Resolving the spatial and temporal evolution of changes in the elevation of mountain belts provides constraints on the geodynamic mechanisms that caused surface uplift of these regions. Several recent studies in the Central Andean plateau (between 13°S and 28°S) have used multiple climate proxies to demonstrate punctuated (several myr) changes in the composition of meteoric water and surface temperature inferred to reflect significant (≥1000 m) surface uplift. These studies suggest that different regions experienced surface uplift at different times. In comparison with crustal thickening histories derived from reconstructions of crustal shortening, it is also clear that crustal thickening and surface uplift are temporally decoupled, with significant crustal thickening preceding punctuated surface uplift events by several tens of millions of years. Here we compile results from paleoclimate studies of the Central Andean plateau to infer regional patterns of surface uplift. Limited paleoclimate data and geologic evidence indicate that the Eastern Cordillera experienced an earlier pulse of surface uplift than the Altiplano zone, associated with an eastward sweep of magmatism that marks the current limits of the plateau. Within the Altiplano zone, the southern Altiplano appears to have risen beginning in middle Miocene time and continuing through late Miocene time. During this time, the north-central Altiplano remained low and experienced increasing rates of sedimentation. In late Miocene time, sedimentation rates slowed dramatically at the same time that climate proxy data suggest rapid surface uplift of the north-central Altiplano. The northernmost Altiplano of Peru experienced a pulse of surface uplift in middle Miocene to early Pliocene time, with the exact timing unconstrained as of yet. Crustal shortening reconstructions from the southern through the north-central plateau (between 17°S and 24°S) yield upper estimates that range between 300×20 km, sufficient

  3. Andean uplift and Neogene climate change in the Atacama Desert

    Science.gov (United States)

    Rech, J. A.; Currie, B. S.; Jordan, T. E.

    2006-12-01

    Today the Andean Cordillera and Altiplano provide a major obstacle to atmospheric circulation over South America. The Altiplano Plateau prevents moist air masses from the Amazon Basin from reaching the Atacama Desert, causing the Atacama to be one of the driest places on Earth. Although Neogene sedimentary records from the western flank of the Andes should record the dramatic shift to hyperaridity that resulted from the growth of the Altiplano Plateau, the climatic implications of many sedimentary sequences have been difficult to decipher. The causes of the difficulties are complex, such as the relative influences of tectonics and active volcanism versus climate, and the roles of local as well as regional precipitation on groundwater and on the deposition of paludal sediments in basin centers. Over the last few years our research group has focused on using paleosols and the isotopic composition of palustrine carbonates in the Calama Basin (22°S) to try to identify a local precipitation signal and determine the onset of extreme hyperaridity as a consequence of the growth of the Altiplano. We have determined the soil morphological characteristics, salt chemistry, and mass independent fractionation anomalies (Δ17O values) in dated paleosols to reconstruct a Middle Miocene climatic transition from semi-aridity to extreme hyperaridity in the Atacama Desert. Paleosols along the southeastern margin of the Calama Basin change from calcic Vertisols with root traces, slickensides, and gleyed horizons to an extremely mature salic Gypsisol with pedogenic nitrate. We interpret this transition, which occurred between 19 and 13 Ma, to represent a change in precipitation from >200 mm/yr to Calama Basin also show a marked change during this time period. δ13C values of palustrine carbonates increase from -7 to +7? VPDB and δ18O values increases from -7 to +1? VPDB over the late to Middle Miocene time. This major trend towards more positive values is likely the result of several

  4. Paired Magmatic-Metallogenic Belts in Myanmar - an Andean Analogue?

    Science.gov (United States)

    Gardiner, Nicholas; Robb, Laurence; Searle, Michael; Morley, Christopher

    2015-04-01

    contrasting minerals endowment. The Mogok-Mandalay-Mergui (MMM) Belt hosts crustal-melt S-type granites with significant tin-tungsten mineralization, and contains the historically major tungsten deposit of Mawchi. The Wuntho-Popa Arc comprises I-type granites and granodiorites with porphyry-type copper-gold and epithermal gold mineralization, and includes the world-class Monywa copper mine. Recent U-Pb radiometric age dating has shown the potential for the two belts to be both active from the Late Cretaceous to Eocene. The spatial juxtaposition of these two sub-parallel belts, the implication of contemporary magmatism, and their distinct but consistent metallogenic endowment bears strong similarities to the metallogenic belts of the South American Cordillera. Here we investigate whether they together represent the magmatic and metallogenic expression of an Andean-type setting in Myanmar during the subduction of Neo-Tethys. In this analogue the Wuntho-Popa Arc represents a proximal I-type magmatic belt sited immediately above the eastwards-verging Neo-Tethys subduction zone. Exhibiting porphyry-type copper-gold and epithermal gold mineralization, this would therefore be the Myanmar equivalent of the Andean coastal copper belts. Conversely, the parallel MMM Belt, comprised of more distal crustal-melt S-type tin granites, would have an analogue in the Bolivian tin belt.

  5. Paleontologic and stratigraphic relations of phosphate beds in Upper Cretaceous rocks of the Cordillera Oriental, Colombia

    Science.gov (United States)

    Maughan, Edwin K.; Zambrano O., Francisco; Mojica G., Pedro; Abozaglo M., Jacob; Pachon P., Fernando; Duran R., Raul

    1979-01-01

    Phosphorite crops out in the Cordillera Oriental of the Colombian Andes in rocks of Late Cretaceous age as strata composed mostly of pelletal carbonate fluorapatite. One stratum of Santonian age near the base of the Galembo Member of the La Luna Formation crops out at many places in the Departments of Santander and Norte de Santander and may be of commercial grade. This stratum is more than one meter thick at several places near Lebrija and near Sardinata, farther south it is locally one meter thick or more near the base of the Guadalupe Formation in the Department of Boyaca. Other phosphorite beds are found at higher stratigraphic levels in the Galembo Member and the Guadalupe Formation, and at some places these may be commercial also. A stratigraphically lower phosphorite occurs below the Galembo Member in the Capacho Formation (Cenomanian age) in at least one area near the town of San Andres, Santander. A phosphorite or pebbly phosphate conglomerate derived from erosion of the Galembo Member forms the base of the Umir Shale and the equivalent Colon Shale at many places. Deposition of the apatite took place upon the continental shelf in marine water of presumed moderate depth between the Andean geosyncline and near-shore detrital deposits adjacent to the Guayana shield. Preliminary calculations indicate phosphorite reserves of approximately 315 million metric tons in 9 areas, determined from measurements of thickness, length of the outcrop, and by projecting the reserves to a maximum of 1,000 meters down the dip of the strata into the subsurface. Two mines were producing phosphate rock in 1969; one near Turmeque, Boyaca, and the other near Tesalia, Huila.

  6. Effects of the hydrological cycle on the phycoperiphyton assemblage in an Andean foothill stream in Colombia

    OpenAIRE

    María I. Ríos-Pulgarín; Isabel C. Gil-Guarín; Mario Barletta; Néstor J. Mancera-Rodríguez

    2016-01-01

    The Guarinó River is a torrential system that is located in the foothills of the Colombian central Andean mountains that naturally experiences severe hydrological disturbances, which were higher during the Niño-Niña/Southern Oscillation (ENSO) between 2007 and 2010. The seasonal and interannual variabilities in the taxonomic composition, richness and density of phycoperiphyton assemblages (ecological descriptors) from the Guarinó River were examined in relation to the physical and chemical en...

  7. Early Cenozoic Shortening and Foreland Basin Sedimentation in the Marañon Fold-thrust Belt, Central Peruvian Andes

    Science.gov (United States)

    Jackson, L. J.; Carlotto, V.; Horton, B. K.; Rosell, L. N.

    2015-12-01

    The Marañon fold-thrust belt in the westernmost Andes of Peru has long been considered a robust signature of early Cenozoic shortening in the Andean orogenic belt. However, the structural details and potential records of coeval synorogenic sedimentation remain elusive. We report results from new geologic mapping (1:50,000), cross-section construction, and U-Pb geochronology for the Matucana-Ticlio region at 11-12°S along the Lima-La Oroya highway. Zircon U-Pb age data from volcanic rocks and clastic basin fill provide a maximum depositional age of ~43 Ma for a middle Eocene syndeformational unit that we identify as the Anta Formation, which overlies the Paleocene Casapalca Formation. Sedimentary lithofacies and unconformable relationships within the volcaniclastic Anta Formation reveal mixed fluvial, alluvial-fan, and volcanic depositional conditions during shortening accommodated by a NE-verging thrust/reverse fault and corresponding backthrust (here named the Chonta fault system). Our cross-section reconstruction and geochronological data indicate that the region is a critical, possibly unique, zone of the broader NE-directed Marañon fold-thrust belt where pre-Neogene synorogenic sediments and their associated structures are preserved. We interpret this combined structural and basin system as an Eocene-age (Incaic) frontal thrust belt and corresponding foredeep to wedge-top depozone in central Peru. As one of the better-constrained segments of the Marañon fold-thrust belt, this zone provides insight into potential linkages with elusive early Cenozoic (Incaic) structures and foreland basin fill of the Western Cordillera and Altiplano farther south in the central Andean plateau.

  8. 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.

  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. Structures and crustal development of the central andes between 21° and 25°S

    Science.gov (United States)

    Reutter, K.-J.; Giese, P.; Götze, H.-J.; Scheuber, E.; Schwab, K.; Schwarz, G.; Wigger, P.

    The tectonics of the morphostructural units of the Central Andean segment between 21°S and 25°S are reviewed and their relation to the deep crustal structures, as far as known from geophysical research, is discussed. Special regard is given to the superposition of structures due to the stepwise eastward displacement of four arc systems subsequently developing on the continental margin during the Andean Cycle: (1) Lias — Early Cretaceous, (2) Mid-Cretaceous, (3) Latest Cretaceous — Eocene, and (4) Miocene — Holocene. Within these arc systems, three areas of main tectonic activity can be distinguished: The subduction zone and subduction complex, the magmatic arc, and the backarc region. The subduction complexes of the fossil stages are not preserved and the tectonic activity of the present subduction complex affects the continent only locally along the coast. The structures of the four magmatic arcs are exposed respectively in the Coastal Range, the Longitudnal Valley, the Chilean Precordillera, and in the broad area extending from the Preandean Depression to the western part of the Eastern Cordillera. Notwithstanding great structural differences between the individual arcs, there are common features such as the close reationship between deformation and magmatism, the incorporation of basement into fold and horst structures, and conjugate reverse fault systems. In the case of oblique subduction, longitudinal strike slip faulting, which may be left-handed (Atacama Fault of the Coastal Range) or right-handed (West Fissure of the Chilean Precordillera), follows the magmatic arc. In the backarc region, east vergent fold and thrust belts developed only in the stages 3 and 4. All the different arc stages seem to have contributed gradually to crustal thickening as there is a general development in these systems from ensialic marine conditions over an environment of continental lowlands to the present high plateau situation.

  11. Calling the EU's bluff. Who are the real champions of biodiversity and traditional knowledge in the EU-Central American and EU-Community of Andean Nations Association Agreements?

    International Nuclear Information System (INIS)

    Global Europe and the EU's Raw Materials Initiative are designed to bolster the EU's economic position - whatever the cost - in the face of fierce global competition for both markets and resources, especially from emerging economies such as China and India. The EU also fears losing trade to the US, which has already secured trade and investment concessions from countries in the Western hemisphere, through the Dominican Republic-Central American Free Trade Agreement (DR-CAFTA) and other bilateral trade agreements.

  12. Late Glacial-Holocene climatic transition record at the Argentinian Andean piedmont between 33-34° S

    Science.gov (United States)

    Mehl, A. E.; Zárate, M. A.

    2013-10-01

    The Arroyo La Estacada (~33°28' S, 69°02' W), eastern Andean piedmont of Argentina, cuts through an extensive piedmont aggradational unit composed of a dominant late Pleistocene-early Holocene (LP-EH) alluvial sequence including several paleosols. The arroyo sedimentary record exhibits a paleosol developed affecting the topmost part of likely Lateglacial aeolian deposits aggraded into a floodplain environment by the end of the late Pleistocene. The paleosol shows variable grade of development in the outcrops along the arroyo probably in relation to fluvial valley paleotopography. Organic matter humification, carbonate accumulation and redox processes were the dominant processes associated with paleosol formation. By the early Holocene, when the formation of the paleosol ended, alluvial aggradation renewed and a higher frequency of flooding events could have affected the arroyo's floodplain environment. A period of relative landscape stability in the Arroyo La Estacada basin is inferred from the paleosol developed by the LP-EH transition in response to a climatic amelioration in the Andes cordillera piedmont after the Late Glacial arid conditions. The renewal of early Holocene alluvial aggradation was probably influenced by the South American Monsoon and resulted in a change in the sedimentary dynamics of the arroyo. The analyzed Late Glacial-Holocene alluvial record of the Andean piedmont constitutes a suitable record of the LP-EH climatic transition at the extra Andean region of Argentina. It is in agreement with regional paleoclimatic evidence along the southern tip of the South American continent, where other sedimentary sequences record similar late Quaternary paleoenvironmental changes over both fluvial and interfluvial areas.

  13. Varying mechanical coupling along the Andean margin: Implications for trench curvature, shortening and topography

    Science.gov (United States)

    Iaffaldano, G.; Di Giuseppe, E.; Corbi, F.; Funiciello, F.; Faccenna, C.; Bunge, H.-P.

    2012-03-01

    Convergent margins often exhibit spatial and temporal correlations between trench curvature, overriding plate shortening and topography uplift that provide insights into the dynamics of subduction. The Andean system, where the Nazca plate plunges beneath continental South America, is commonly regarded as the archetype of this class of tectonics systems. There is distinctive evidence that the degree of mechanical coupling between converging plates, i.e. the amount of resistive force mutually transmitted in the direction opposite to their motions, may be at the present-day significantly higher along the central Andean margin compared to the northern and southern limbs. However quantitative estimates of such resistance are still missing and would be desirable. Here we present laboratory models of subduction performed to investigate quantitatively how strong lateral coupling variations need to be to result in trench curvature, tectonic shortening and distribution of topography comparable to estimates from the Andean margin. The analogue of a two-layers Newtonian lithosphere/upper mantle system is established in a silicone putty/glucose syrup tank-model where lateral coupling variations along the interface between subducting and overriding plates are pre-imposed. Despite the simplicity of our setup, we estimate that coupling in the central margin as large as 20% of the driving force is sufficient to significantly inhibit the ability of the experimental overriding plate to slide above the subducting one. As a consequence, the central margin deforms and shortens more than elsewhere while the trench remains stationary, as opposed to the advancing lateral limbs. This causes the margin to evolve into a peculiar shape similar to the present-day trench of the Andean system.

  14. 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.

  15. Climate Change Impacts in a Colombian Andean Tropical Basin

    Science.gov (United States)

    Ocampo, O. L.; Vélez, J. J.; Londoño, A.

    2012-12-01

    Climate change and climate variability have a large impact on water resources. Developing regions have less capacity to prepare for, respond to, and recover from climate-related hazards and effects, and then, populations may be disproportionately affected. In Colombia, the geographical location and the marked irregularity in the terrain, give as a result, a complex climate. These factors have contributed to the water supply of the territory. Unfortunately, the visualization of abundant and inexhaustible water resources created a great disregard for them. Besides, the water supply is not distributed uniformly across the country, and then there is water-deficit in some areas as Andean Region, where the largest population and the main development centers are located. In recent decades, water conflicts have emerged locally and regionally, which have generated a crisis in the allocation mechanisms and have improved the understanding of the water situation in Colombia. The Second National Communication to CCMNU alerts on possible future consequences of climate change and the need for regional studies for understanding climate change impacts on the fragile ecosystems of high mountains as paramos and fog forest, which are water production regulators. Colombian water resources are greatly affected by changes in rainfall patterns influenced by El Niño and La Niña. The recent disasters in the 2010-2011 rainy seasons have caught the attention of not only the authorities but from the scientific community to explore strategies to improve water management by tracking, anticipating and responding to climate variability and climate change. Whereas sound water management is built upon long-term, the country is undertaking a pilot exercise for the integrated management of water resources, five Basins are selected, among them, is the Chinchiná River Basin; this Andean tropical Basin is located on the western slopes at the central range in the Andes between 4°48 and 5°12 N

  16. Agronomic performance and stability of andean common bean lines with white grains in Brazil

    Directory of Open Access Journals (Sweden)

    Helton Santos Pereira

    2014-06-01

    Full Text Available This work evaluated the effect of genotype by environment interaction in Andean common bean lines with white grains, in Central Southern Brazil, to identify lines with high agronomic performance, stability and adaptability, aiming to meet domestic demand and to increase the Brazilian participation in the foreign market of common bean. Nineteen trials with twelve Andean lines were conducted in 2007, 2008 and 2009, in Central Southern Brazil. Grain yield and other agronomic traits were evaluated. Data were subjected to analysis of variance and of adaptability/stability using Annicchiarico and modified AMMI methods. Significant differences were found between lines for all traits evaluated. Genotype by environment interaction was important for lines with Andean origin and white seed. The utilization of weighted mean of absolute scores and yield with the AMMI results enabled the identification of the most stable and adapted lines. Lines Poroto Alubia, CNFB 16211, Ouro Branco and WAF 160 were stable and adapted, using both methods. CNFB 16211 line presented high agronomic performance, stability and adaptability and therefore this line may be a new cultivar. USWA 70 and WAF 75 lines presented grain size similar to that required by the foreign market and superior to the Brazilian cultivars, besides favorable agronomic traits, and thus these lines may be indicated as new cultivars.

  17. The nature of orogenic crust in the central Andes

    Science.gov (United States)

    Beck, Susan L.; Zandt, George

    2002-10-01

    The central Andes (16°-22°S) are part of an active continental margin mountain belt and the result of shortening of the weak western edge of South America between the strong lithospheres of the subducting Nazca plate and the underthrusting Brazilian shield. We have combined receiver function and surface wave dispersion results from the BANJO-SEDA project with other geophysical studies to characterize the nature of the continental crust and mantle lithospheric structure. The major results are as follows: (1) The crust supporting the high elevations is thick and has a felsic to intermediate bulk composition. (2) The relatively strong Brazilian lithosphere is underthrusting as far west (65.5°W) as the high elevations of the western part of the Eastern Cordillera (EC) but does not underthrust the entire Altiplano. (3) The subcrustal lithosphere is delaminating piecemeal under the Altiplano-EC boundary but is not completely removed beneath the central Altiplano. The Altiplano crust is characterized by a brittle upper crust decoupled from a very weak lower crust that is dominated by ductile deformation, leading to lower crustal flow and flat topography. In contrast, in the high-relief, inland-sloping regions of the EC and sub-Andean zone, the upper crust is still strongly coupled across the basal thrust of the fold-thrust belt to the underthrusting Brazilian Shield lithosphere. Subcrustal shortening between the Altiplano and Brazilian lithosphere appears to be accommodated by delamination near the Altiplano-EC boundary. Our study suggests that orogenic reworking may be an important part of the "felsification" of continental crust.

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

    OpenAIRE

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

    2016-01-01

    Seasonal snow cover is the primary water source for human use and ecosystems along the extratropical Andes Cordillera. Despite its importance, relatively little research has been devoted to understanding the properties, distribution and variability of this natural resource. This research provides high-resolution (500 m), daily distributed estimates of end-of-winter and spring snow water equivalent over a 152 000 km2 domain that includes the mountainous reaches of central Chi...

  19. The magmatic history of the Vetas-California mining district, Santander Massif, Eastern Cordillera, Colombia

    Science.gov (United States)

    Mantilla Figueroa, Luis C.; Bissig, Thomas; Valencia, Víctor; Hart, Craig J. R.

    2013-08-01

    The Vetas-California Mining District (VCMD), located in the central part of the Santander Massif (Colombian Eastern Cordillera), based on U-Pb dating of zircons, records the following principal tectono-magmatic events: (1) the Grenville Orogenic event and high grade metamorphism and migmatitization between ˜1240 and 957 Ma; (2) early Ordovician calc-alkalic magmatism, which was synchronous with the Caparonensis-Famatinian Orogeny (˜477 Ma); (3) middle to late Ordovician post-collisional calc-alkalic magmatism (˜466-436 Ma); (4) late Triassic to early Jurassic magmatism between ˜204 and 196 Ma, characterized by both S- and I-type calc-alkalic intrusions and; (5) a late Miocene shallowly emplaced intermediate calc-alkaline intrusions (10.9 ± 0.2 and 8.4 ± 0.2 Ma). The presence of even younger igneous rocks is possible, given the widespread magmatic-hydrothermal alteration affecting all rock units in the area. The igneous rocks from the late Triassic-early Jurassic magmatic episodes are the volumetrically most important igneous rocks in the study area and in the Colombian Eastern Cordillera. They can be divided into three groups based on their field relationships, whole rock geochemistry and geochronology. These are early leucogranites herein termed Alaskites-I (204-199 Ma), Intermediate rocks (199-198 Ma), and late leucogranites, herein referred to as Alaskites-II (198-196 Ma). This Mesozoic magmatism is reflecting subtle changes in the crustal stress in a setting above an oblique subduction of the Panthalassa plate beneath Pangea. The lower Cretaceous siliciclastic Tambor Formation has detrital zircons of the same age populations as the metamorphic and igneous rocks present in the study area, suggesting that the provenance is related to the erosion of these local rocks during the late Jurassic or early Cretaceous, implying a local supply of sediments to the local depositional basins.

  20. Growth and gravitational collapse of a mountain front of the Eastern Cordillera of Colombia

    Science.gov (United States)

    Kammer, Andreas; Montana, Jorge; Piraquive, Alejandro

    2016-04-01

    The Eastern Cordillera of Colombia is bracketed between the moderately east-dipping flank of the Central Cordillera on its western and the gently bent Guayana shield on its eastern side. It evolved as a response to a considerable displacement transfer from the Nazca to the Southamerican plate since the Oligocene break-up of the Farallon plate. One of its distinctive traits refers to its significant shortening by penetrative strain at lower and folding at higher structural levels, approximating a wholesale pure-shear in analogy to a vice model or a crustal welt sandwiched between rigid buttresses. This contrasting behavior may be explained by the spatial coincidence between Neogene mountain belt and a forebulge that shaped the foreland trough during a Cretaceous subduction cycle and was very effective in localizing a weakening of the backarc region comprised between two basin margin faults. In this paper we examine a two-phase evolution of the Eastern mountain front. Up to the late Miocene deformation was restrained by the inherited eastern basin margin fault and as the cordilleran crust extruded, a deformation front with an amplitude similar the present structural relief of up to 10.000 m may have built up. In the Pliocene convergence changed from a roughly strike-perpendicular to an oblique E-W direction and caused N-S trending faults to branch off from the deformation front. This shortening was partly driven by a gravitational collapse of the Miocene deformation front, that became fragmented by normal faults and extruded E on newly formed Pliocene thrust faults. Normal faults display displacements of up to 3000 m and channelized hydrothermal fluids, leading to the formation of widely distributed fault breccias and giving rise to a prolific Emerald mineralization. In terms of wedge dynamics, the Pliocene breaching of the early formed deformation front helped to establish a critical taper.

  1. A new species of salamander (Bolitoglossa: Plethodontidae from the Cordillera Oriental of the Colombian Andes

    Directory of Open Access Journals (Sweden)

    Andrés R. Acosta-Galvis

    2012-01-01

    Full Text Available Eight species of salamanders are recognized to Cordillera Oriental of Colombia. Here we describe a new species of the genus Bolitoglossa, named Bolitoglossa guaneae sp. nov. The highest number of species of this genus is found in the cloud forests located in the western flank of the Cordillera Oriental.

  2. Quinoa trade in Andean countries: opportunities and challenges for family

    OpenAIRE

    Baudoin, Andrea; Lacroix, Pierril; Didier BAZILE; Chia, Eduardo

    2015-01-01

    Quinoa’s revival has roused much interest in Andean as well as in European and North American countries. This Andean product, formerly denigrated and destined only for self-consumption, has made its way into the diet of the urban populations of Andean countries and has now spread to the United States of America, Europe and other parts of the world. In the Andes, farmgate prices have gone up and the quinoa sector has become attractive to investors. A wide range of products based on this Chenop...

  3. Birds of Two Oceans? Trans-Andean and Divergent Migration of Black Skimmers (Rynchops niger cinerascens from the Peruvian Amazon.

    Directory of Open Access Journals (Sweden)

    Lisa C Davenport

    Full Text Available Seasonal flooding compels some birds that breed in aquatic habitats in Amazonia to undertake annual migrations, yet we know little about how the complex landscape of the Amazon region is used seasonally by these species. The possibility of trans-Andes migration for Amazonian breeding birds has largely been discounted given the high geographic barrier posed by the Andean Cordillera and the desert habitat along much of the Pacific Coast. Here we demonstrate a trans-Andes route for Black Skimmers (Rynchops niger cinerascens breeding on the Manu River (in the lowlands of Manu National Park, Perú, as well as divergent movement patterns both regionally and across the continent. Of eight skimmers tracked with satellite telemetry, three provided data on their outbound migrations, with two crossing the high Peruvian Andes to the Pacific. A third traveled over 1800 km to the southeast before transmissions ended in eastern Paraguay. One of the two trans-Andean migrants demonstrated a full round-trip migration back to its tagging location after traveling down the Pacific Coast from latitude 9° South to latitude 37° S, spending the austral summer in the Gulf of Arauco, Chile. This is the first documentation of a trans-Andes migration observed for any bird breeding in lowland Amazonia. To our knowledge, this research also documents the first example of a tropical-breeding waterbird migrating out of the tropics to spend the non-breeding season in the temperate summer, this being the reverse pattern with respect to seasonality for austral migrants in general.

  4. Birds of Two Oceans? Trans-Andean and Divergent Migration of Black Skimmers (Rynchops niger cinerascens) from the Peruvian Amazon.

    Science.gov (United States)

    Davenport, Lisa C; Goodenough, Katharine S; Haugaasen, Torbjørn

    2016-01-01

    Seasonal flooding compels some birds that breed in aquatic habitats in Amazonia to undertake annual migrations, yet we know little about how the complex landscape of the Amazon region is used seasonally by these species. The possibility of trans-Andes migration for Amazonian breeding birds has largely been discounted given the high geographic barrier posed by the Andean Cordillera and the desert habitat along much of the Pacific Coast. Here we demonstrate a trans-Andes route for Black Skimmers (Rynchops niger cinerascens) breeding on the Manu River (in the lowlands of Manu National Park, Perú), as well as divergent movement patterns both regionally and across the continent. Of eight skimmers tracked with satellite telemetry, three provided data on their outbound migrations, with two crossing the high Peruvian Andes to the Pacific. A third traveled over 1800 km to the southeast before transmissions ended in eastern Paraguay. One of the two trans-Andean migrants demonstrated a full round-trip migration back to its tagging location after traveling down the Pacific Coast from latitude 9° South to latitude 37° S, spending the austral summer in the Gulf of Arauco, Chile. This is the first documentation of a trans-Andes migration observed for any bird breeding in lowland Amazonia. To our knowledge, this research also documents the first example of a tropical-breeding waterbird migrating out of the tropics to spend the non-breeding season in the temperate summer, this being the reverse pattern with respect to seasonality for austral migrants in general. PMID:26760301

  5. Nuclear ribosomal internal transcribed spacer 1 (ITS1) variation in the Anastrepha fraterculus cryptic species complex (Diptera, Tephritidae) of the Andean region

    Science.gov (United States)

    The nuclear ribosomal internal transcribed spacer 1 (ITS1) was sequenced for Anastrepha fraterculus (Wiedemann, 1830) originating from 85 collections from the northern and central Andean countries of South America including Argentina (Tucumán), Bolivia, Perú, Ecuador, Colombia, and Venezuela. The IT...

  6. Andean flat subduction maintained by slab tunneling

    Science.gov (United States)

    Schepers, Gerben; van Hinsbergen, Douwe; Kosters, Martha; Boschman, Lydian; McQuarrie, Nadine; Spakman, Wim

    2016-04-01

    In two segments below the Andean mountain belt, the Nazca Plate is currently subducting sub-horizontally below South America over a distance of 200-300 km before the plate bends into the mantle. Such flat slab segments have pronounced effects on orogenesis and magmatism and are widely believed to be caused by the downgoing plate resisting subduction due to its local positive buoyancy. In contrast, here we show that flat slabs primarily result from a local resistance against rollback rather than against subduction. From a kinematic reconstruction of the Andean fold-thrust belt we determine up to ~390 km of shortening since ~50 Ma. During this time the South American Plate moved ~1400 km westward relative to the mantle, thus forcing ~1000 km of trench retreat. Importantly, since the 11-12 Ma onset of flat slab formation, ~1000 km of Nazca Plate subduction occurred, much more than the flat slab lengths, which leads to our main finding that the flat slabs, while being initiated by arrival of buoyant material at the trench, are primarily maintained by locally impeded rollback. We suggest that dynamic support of flat subduction comes from the formation of slab tunnels below segments with the most buoyant material. These tunnels trap mantle material until tearing of the tunnel wall provides an escape route. Fast subduction of this tear is followed by a continuous slab and the process can recur during ongoing rollback of the 7000 km wide Nazca slab at segments with the most buoyant subducting material, explaining the regional and transient character of flat slabs. Our study highlights the importance of studying subduction dynamics in absolute plate motion context.

  7. Soil organic matter dynamics at the paramo and puna highlands in the Andean mountains

    Science.gov (United States)

    Ángeles Muñoz, M.; Faz, Ángel; Mermut, Ahmet R.; Zornoza, Raúl

    2014-05-01

    Mountains and uplands represent the most diverse and fragile ecosystems in the world, cover about 20% of the terrestrial surface and are distributed across all continents and major ecoregions. The Andean Plateau is the main mountain range of the American continent and one of the largest in the world with more than 7,500 km. The soil organic matter is a corner stone in the fertility management of the Andean agriculture as well as in the erosion control. However, its role is still much unknown in these ecosystems. Moreover, the influence of current global climatic change on soil organic C reservoirs and dynamics is still not clearly understood. The aim of this work was to review the soil C dynamics and the implication of the soil organic matter in the fertility management, erosion control, conservation of biodiversity and global climate change to improve the knowledge on the mountain Andean highlands. Climate, landscape, soil C pools, biomass and management were studied. In general, the Andean climate is affected by three main factors: ocean currents, winds and orography characterized by an abrupt topography. The entire Andean belt is segmented into the Northern, Central and Southern Andes. Northern Andes are called paramo and are characterized by humid climate while Central and Southern Andes dryer zones are called puna. Most of the region is tectonically and volcanically active. Sedimentary rocks predominated in the paramo while sedimentary, igneous and metamorphic ones prevailed in the puna. The most common soils were Andosols, Regosols, Umbrisols and Histosols. The cold and wet climate and the low atmospheric pressure favored organic matter accumulation in the soil. The accumulation of organic matter is further enhanced by the formation of organomineral complexes strongly resistant to the microbial breakdown mainly in the paramo. High organic C contents were observed in the paramo (10%) oppositely to the low contents found in the dryer puna (1%). The C/N ratio

  8. The new Andean Regional Office of Astronomy for Development (ROAD)

    Science.gov (United States)

    Char, Farid; Forero-Romero, Jaime

    2015-08-01

    The Andean Regional Office of Astronomy for Development (ROAD) is a new effort in South America to serve several goals in astronomical development. Six countries (Bolivia, Colombia, Chile, Ecuador, Perú and Venezuela) will work together, representing a common language block in the Andean region and focusing on develop strategies to strengthen the professional research, education and popularization of astronomy. Our current Working Structure comprises a ROAD Coordinator and Coordinators per Task Force, as well as Organizing Committees, Collaborators and Volunteers.The participating institutions of this new ROAD have been involved in many projects involving each of the current OAD’s Task Forces: research, schools and children and public, exploring educational activities/material to be shared among the Andean countries, standardizing the knowledge and creating inspirational experiences. We expect to generate many efforts in order to bring a more homogeneous activity in each Andean country, taking into account the special role of Chile in global astronomy, due to its great conditions for astronomy and the involvement of many professional observatories, universities and astronomy institutions.Our current (and upcoming) most relevant activities includes: Andean Schools on Astronomy, Andean Graduate Program and Massive Open Online Courses (TF1); Virtual Training Sessions and Teaching material for the visually impaired students; Annual TF2 meeting to gather all the collaborators (TF2); Development for planetariums and Communicating Astronomy with the Public (TF3). The Andean region, in the other hand, will also be involved in at least two important events: the CAP Meeting in May 2016 and the XV LARIM in October 2016 (both in Colombia); and Chile will bid to host the XXXI IAU GA in 2021, with the aim of show the great advances in astronomical development from the Andean region and South America.

  9. An ontological approach to creating an Andean Weaving Knowledge Base

    OpenAIRE

    Brownlow, Richard; Capuzzi, Stefano; Helmer, Sven; Martins, Luciana; Normann, Immanuel; Poulovassilis, Alexandra

    2015-01-01

    Andean textiles are products of one of the richest, oldest and continuous weaving traditions in the world. Understanding the knowledge and practice of textile production as a form of cultural heritage is particularly relevant in the Andean context due to erosion of clothing traditions, reuse of traditional textiles on commodities targeted at the tourism market, and loss of knowledge embedded in textile production. ``Weaving Communities of Practice'' was a pilot project that aimed to create a ...

  10. Controls on timing of exhumation and deformation in the northern Peruvian eastern Andean wedge as inferred from low-temperature thermochronology and balanced cross section

    Science.gov (United States)

    Eude, Adrien; Roddaz, Martin; Brichau, Stéphanie; Brusset, Stéphane; Calderon, Ysabel; Baby, Patrice; Soula, Jean-Claude

    2015-04-01

    In northern Peru, a 500 km long regional balanced section has been constructed across the eastern Andean wedge, using fieldwork, industrial seismic sections, and wells. The structure is characterized by a thin-skinned thrust system involving the Eastern Cordillera (EC), the sub-Andean zone (SAZ), and the Marañón foredeep. In the SAZ and the easternmost foredeep the development of the thrust system has been driven by the combination of two structural events. Permian thrust faults had been reactivated to form a basement duplex underlying the SAZ and the foredeep. At the same time a Triassic-Jurassic extensional basin has been transported as a crustal ramp anticline on to the duplex roof fault, giving rise to the EC. The impingement of the EC was responsible for the deformation of the SAZ and the propagation of the thrust wedge. The minimum shortening calculated is 142 km, representing a shortening strain of ~ -28%. A sequential restoration calibrated by (U-Th)/He and Fission Track dating on apatites and vitrinite reflectance values shows that shortening rates vary from 7.1 mm yr-1 between 17 and 8 Ma to 3.6 mm yr-1 between 8 Ma and today and suggests that the thrust wedge commenced propagation between 30 and 24 Ma. When compared with other Andean thrust wedges, we suggest that the timing of the thrust wedge propagation is not a simple function of the distance to the hinge of the Bolivian orocline and the propagation is not controlled by the precipitation regime. We rather suggest that reactivated basement faults favored thrust wedge propagation.

  11. Multiple glacial culminations from the Lateglacial to the late Holocene in central and southern Peru (Invited)

    Science.gov (United States)

    Licciardi, J. M.; Schaefer, J. M.; Rodbell, D. T.; Stansell, N.; Schweinsberg, A.; Finkel, R. C.; Zimmerman, S. R.

    2013-12-01

    Fluctuations in small tropical mountain glaciers serve as sensitive indicators of variations in past and present-day climate. Most of the world's modern tropical glaciers reside in the Peruvian Andes, where a growing number of well-dated glacial records have recently been developed. As additional records are documented, regional patterns of late Pleistocene to Holocene glacial activity have begun to emerge. Here we present a compilation of new and previously obtained 10Be surface exposure ages from boulders on well-preserved moraine successions in two glaciated Andean ranges: the Cordillera Vilcabamba of southern Peru (13°20'S, 72°32'W) and the Huaguruncho massif (10°32'S, 75°56'W), located in central Peru ~450 km northwest of the Vilcabamba. A high-resolution composite chronology that merges >100 10Be measurements on moraine sequences in five glaciated drainages of the Cordillera Vilcabamba reveals the occurrence of at least five discrete glacial culminations from the Lateglacial to the late Holocene. At the Huaguruncho massif, >20 10Be exposure ages obtained from moraine sequences in a south-facing cirque indicate at least three major glacial stages spanning the Lateglacial to the Little Ice Age. The moraine ages at Huaguruncho are broadly correlative with the Vilcabamba moraine chronologies, with some dated moraine belts exhibiting geomorphic expressions that closely resemble those of their coeval counterparts in the Vilcabamba. A recurring finding in both field areas is a mismatch between basal radiocarbon ages from bog and lake sediments and 10Be exposure ages on outboard moraines, which enclose the depositional basins. These age discrepancies suggest that cosmogenic 10Be production rates scaled to high altitudes in the tropics are substantially lower than previous estimates. While we anticipate that future refinements to scaled isotope production rates may significantly affect correlation of 10Be exposure ages in the high Andes with ages derived from

  12. Unraveling Tropical Mountain Hydroclimatology by Coupling Autonomous Sensor Observations and Climate Modeling: Llanganuco Valley, Cordillera Blanca, Peru.

    Science.gov (United States)

    Hellstrom, R. A.; Fernandez, A.; Mark, B. G.; Covert, J. M.

    2015-12-01

    Northern Peru will face critical water resource issues in the near future as permanent ice retreats. Much of current global and regional climate research neglects the meteorological forcing of lapse rates and valley wind dynamics on critical components of the Peruvian Andes' water-cycle. In 2004 and 2005 we installed an autonomous sensor network (ASN) within the glacierized Llanganuco Valley, Cordillera Blanca (9°S), consisting of discrete, cost-effective, automatic temperature loggers located along the valley axis and anchored by two automatic weather stations. Comparisons of these embedded atmospheric measurements from the ASN and climate modeling (CM) by dynamical downscaling using the Weather Research and Forecasting (WRF) model elucidate distinct diurnal and seasonal characteristics of the mountain valley winds and lapse rates. Wind, temperature, humidity, and cloud simulations by WRF suggest that thermally driven valley winds converging with easterly flow aloft enhance late afternoon and evening cloud development which helps explain detected nocturnal precipitation maxima measured by the ASN. We attribute sustained evapotranspiration (ET), as estimated by the FAO-56 Penman-Monteith model, to an abundance of glacial melt-water during the dry season and strong pre-noon solar heating during the wet season. Furthermore, the extreme diurnal variability of along-valley-axis lapse rates and valley wind detected from ground observations and confirmed by dynamical downscaling demonstrate the importance of realistic scale parameterizations of the boundary layer to improve regional CM projections in mountainous regions. Our findings portray ET as an integral yet poorly represented process in Andean hydroclimatology. We show that coupling ASN and CM can improve understanding of multi-scale atmospheric and associated hydrological processes in mountain valleys.

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

    Science.gov (United States)

    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.

  14. Holocene denudation and landscape deformation in the Cordillera Blanca, Peru

    Science.gov (United States)

    Hodson, K. R.; Hall, S. R.; Michalak, M.; Farber, D.; Hourigan, J. K.

    2012-12-01

    Active orogenic systems are subject to a host of processes that influence their topographic and structural evolution. Broadly speaking, these processes can be divided into two general groups: tectonics and climate. Both are capable of inducing profound changes within an orogen, although many specifics regarding their forcings, interactions, and feedbacks remain unclear. Here, we address the evolution of the Cordillera Blanca Mountain Range of northern Peru: an elevated, high-relief, 200km long string of glaciated peaks along the spine of the Andes. The striking Cordillera Blanca Detachment Fault (CBDF) is actively facilitating the production of several kilometers of relief along the western flank of the range, and abundant records of past glaciations span from >440 ka to the present. Thus, tectonics (active faulting) and climate (glacial erosion) are operating in tandem to produce some of the highest topography in the western hemisphere, affording the opportunity to investigate their potential interactions. Through the use of cosmogenic 10Be, low temperature thermochronology and digital terrain analysis we characterize the rates of landscape change as well as the present morphology. Significant variation in range elevation (maximum, mean, modal and minimum), relief (local and within basins) and slope (maximum, mean and minimum) exist along the strike of the range, potentially reflecting variable displacement along the CBDF, varying degrees of glacial erosion along the mountain range, or some combination of the two. The morphology of the adjacent supradetachment basin varies as well, containing zones with distinct styles of faulting and basin growth likely defined by the segmentation history of the CBDF. New thermochronologic data extends the current dataset, which we combine with 10Be basin-averaged erosion rates from basins along the range. These two datasets constrain the exhumational and erosional history of the range-forming Cordillera Blanca Batholith from the

  15. Architecture of the Northwest Andean Microplates

    Science.gov (United States)

    Potts, L. V.; Hernandez, O.; von Frese, R. R.; Schmidt, M.

    2005-05-01

    Recently revised models on global plate boundary zones show that the North Andes microplate includes a wide distribution of seismicity, volcanic events, active faulting and extreme topography. The current description of the north Andean microplate boundaries is interpreted from a variety of geological and geophysical models including volcanism and seismicity with variable confidence levels. The poorly understood complex structure and geometry of plate boundaries limits the ability of current physical models to predict neotectonic and other effects including intra-plate lithospheric stresses and strain. Together with local surface gravity and topography data, a variety of available space geodetic sensors have substantially improved the modeling of the lithosphere for analyzing subsurface mass dynamics. They include the GPS-derived 3-D crustal velocities, high resolution (90-m) topography, seismic surveys and high resolution gravity models derived from integrated satellite (e.g., CHAMP and GRACE, 200-km resolution) and terrestrial observations (up to ~5 km resolution). Spherical wavelets is a modern tool for a multi-resolution representation of spatially heterogenously distributed gravity (consistent with the generalized boundary value problem) and for topography datasets with the distinct ability to enhance localized signals. Analysis of multi-resolution gravity and topography models combined with GPS velocities provide a unique opportunity to characterize the structure, isostatic conditions, mass dynamics, and intra-plate deformations of the North Andes microplate.

  16. Andean tectonics: Implications for Satellite Geodesy

    Science.gov (United States)

    Allenby, R. J.

    1984-09-01

    Current knowledge and theories of large scale Andean tectonics as they relate to site planning for the NASA Crustal Dynamics Program's proposed high precision geodetic measurements of relative motions between the Nazca and South American plates are summarized. The Nazca Plate and its eastern margin, the Peru-Chile Trench, is considered a prototype plate marked by rapid motion, strong seismicity and well defined boundaries. Tectonic activity across the Andes results from the Nazca Plate subducting under the South American plate in a series of discrete platelets with different widths and dip angles. This in turn, is reflected in the tectonic complexity of the Andes which are a multitutde of orogenic belts superimposed on each other since the Precambrian. Sites for Crustal Dynamics Program measurements are being located to investigate both interplate and extraplate motions. Observing operations have already been initiated at Arequipa, Peru and Easter Island, Santiago and Cerro Tololo, Chile. Sites under consideration include Iquique, Chile; Oruro and Santa Cruz, Bolivia; Cuzco, Lima, Huancayo and Bayovar, Peru; and Quito and the Galapagos Islands, Ecuador. Based on scientific considerations, Santa Cruz, Huancayo (or Lima), Quito and the Galapagos Islands should be replaced by Isla San Felix, Chile; Brazilia or Petrolina, Brazil; and Guayaquil, Ecuador. If resources permit, additional important sites would be Buenaventura and Villavicencio or Puerto La Concordia, Colombia; and Mendoza and Cordoba, Argentina.

  17. Nuclear ribosomal internal transcribed spacer 1 (ITS1) variation in the Anastrepha fraterculus cryptic species complex (Diptera, Tephritidae) of the Andean region

    OpenAIRE

    Sutton, Bruce D.; Steck, Gary J.; Norrbom, Allen L.; Rodriguez, Erick J.; Srivastava,Pratibha; Alvarado, Norma Nolazco; Colque,Fredy; Landa, Erick Yábar; Sánchez, Juan José Lagrava; Quisberth, Elizabeth; Peñaranda, Emilio Arévalo; Clavijo,P.A. Rodriguez; Alvarez-Baca, Jeniffer K.; Zapata, Tito Guevara; Ponce, Patricio

    2015-01-01

    Abstract The nuclear ribosomal internal transcribed spacer 1 (ITS1) was sequenced for Anastrepha fraterculus (Wiedemann, 1830) originating from 85 collections from the northern and central Andean countries of South America including Argentina (Tucumán), Bolivia, Perú, Ecuador, Colombia, and Venezuela. The ITS1 regions of additional specimens (17 collections) from Central America (México, Guatemala, Costa Rica, and Panamá), Brazil, Caribbean Colombia, and coastal Venezuela were sequenced and t...

  18. How to Deepen the Dialogue between the Andean Community and the EU

    OpenAIRE

    Sheila Page

    2007-01-01

    This paper discusses the European Union trade policy making process and implications for the Andean community. The European Union (EU) divides its agreements with other countries into three types: neighbourhood, trade and development, and is currently classifying the negotiations with the Andean Community as development. The Andean Community must examine how the EU has approached its agreements in the past and what the Andean countries need from an agreement, and decide whether it wants to ne...

  19. IAI Global Change Agenda and Support of Higher Education in the Andean Amazon Countries.

    Science.gov (United States)

    Galarraga, R.; McClain, M.; Fierro, V.

    2007-05-01

    The Andean Amazon River Analysis and Management project, an IAI Collaborative Research Network operating during 1999-2004, examined the impacts of climate and land-use changes on the hydrobiogeochemistry of rivers draining the Amazon Andes of Ecuador, Peru, Colombia and Bolivia. The project also provided a means to strengthen scientific collaboration among these Andean countries and the USA. Research in these countries was carried out under the guidance of investigators with backgrounds in the relevant environmental fields, but the bulk of the research activities were carried out by undergraduate and graduate students who studied within these countries and overseas. Twenty graduate students and 15 undergraduates completed studies within the project, in topics related to monitoring hydrometeorological variables both in time and space. Student research and capacity building were focused in areas central to global environmental change, including modeling of precipitation and precipitation-runoff processes, basin-scale water quality characterization and biogeochemical cycling, and socioeconomic controls on the use and management of riverine resources. The analysis of human dimension aspects of climate change research was also featured, especially those aspects that linked the consequences of water quality degradation on human health. Most of undergraduate and graduate students that collaborated in the AARAM project have joined national environmental institutions and some have continued for higher scientific degrees in fields closely related to the IAI scientific agenda. Through this IAI initiative, the number of trained global change scientists in the Andean countries has grown and there is enhanced awareness of key global change science issues among the scientific community.

  20. Constraining the crustal root geometry beneath the Rif Cordillera (North Morocco)

    Science.gov (United States)

    Diaz, Jordi; Gil, Alba; Carbonell, Ramon; Gallart, Josep; Harnafi, Mimoun

    2016-04-01

    The analyses of wide-angle reflections of controlled source experiments and receiver functions calculated from teleseismic events provide consistent constraints of an over-thickened crust beneath the Rif Cordillera (North Morocco). Regarding active source data, we investigate now offline arrivals of Moho-reflected phases recorded in RIFSIS project to get new estimations of 3D crustal thickness variations beneath North Morocco. Additional constrains on the onshore-offshore transition are derived from onland recording of marine airgun shots from the coeval Gassis-Topomed profiles. A regional crustal thickness map is computed from all these results. In parallel, we use natural seismicity data collected throughout TopoIberia and PICASSO experiments, and from a new RIFSIS deployment, to obtain teleseismic receiver functions and explore the crustal thickness variations with a H-κ grid-search approach. The use of a larger dataset including new stations covering the complex areas beneath the Rif Cordillera allow us to improve the resolution of previous contributions, revealing abrupt crustal changes beneath the region. A gridded surface is built up by interpolating the Moho depths inferred for each seismic station, then compared with the map from controlled source experiments. A remarkably consistent image is observed in both maps, derived from completely independent data and methods. Both approaches document a large modest root, exceeding 50 km depth in the central part of the Rif, in contrast with the rather small topographic elevations. This large crustal thickness, consistent with the available Bouguer anomaly data, favor models proposing that the high velocity slab imaged by seismic tomography beneath the Alboran Sea is still attached to the lithosphere beneath the Rif, hence pulling down the lithosphere and thickening the crust. The thickened area corresponds to a quiet seismic zone located between the western Morocco arcuate seismic zone, the deep seismicity area

  1. On the Nature of Cross-Linguistic Transfer: A Case Study of Andean Spanish

    Science.gov (United States)

    Muntendam, Antje G.

    2013-01-01

    This paper presents the results of a study on cross-linguistic transfer in Andean Spanish word order. In Andean Spanish the object appears in preverbal position more frequently than in non-Andean Spanish, which has been attributed to an influence from Quechua (a Subject-Object-Verb language). The high frequency of preverbal objects could be…

  2. The effects of governance modes on the energy matrix of Andean countries

    Energy Technology Data Exchange (ETDEWEB)

    Fontaine, Guillaume, E-mail: gfontaine@flacso.org.e [Latin American Faculty for Social Sciences (FLACSO), Research Laboratory on Governance, Quito (Ecuador)

    2011-05-15

    This article addresses the consequences of different modes of energy governance on the energy matrix. Energy governance is understood as a regulation system of the energy related interplays between the State, the society and the economy. The energy matrix is a useful instrument for comparative policy analysis, since it informs us about production and consumption trends, by sources and sectors. Our central argument is that energy governance follows two different patterns, one hierarchical and the other cooperative, that are not necessarily determined by the initial factors allocation, and produce different effects on the energy matrix. Hierarchical governance is based on centralized decision-making and State-centered development, while co-governance is based on decentralized decision-making and market-oriented development. To develop this argument, we compare the energy matrix from the five Andean countries (Venezuela, Colombia, Ecuador, Peru and Bolivia).

  3. Nuclear ribosomal internal transcribed spacer 1 (ITS1) variation in the Anastrepha fraterculus cryptic species complex (Diptera, Tephritidae) of the Andean region

    Science.gov (United States)

    Sutton, Bruce D.; Steck, Gary J.; Norrbom, Allen L.; Rodriguez, Erick J.; Srivastava, Pratibha; Alvarado, Norma Nolazco; Colque, Fredy; Landa, Erick Yábar; Sánchez, Juan José Lagrava; Quisberth, Elizabeth; Peñaranda, Emilio Arévalo; Clavijo, P. A. Rodriguez; Alvarez-Baca, Jeniffer K.; Zapata, Tito Guevara; Ponce, Patricio

    2015-01-01

    Abstract The nuclear ribosomal internal transcribed spacer 1 (ITS1) was sequenced for Anastrepha fraterculus (Wiedemann, 1830) originating from 85 collections from the northern and central Andean countries of South America including Argentina (Tucumán), Bolivia, Perú, Ecuador, Colombia, and Venezuela. The ITS1 regions of additional specimens (17 collections) from Central America (México, Guatemala, Costa Rica, and Panamá), Brazil, Caribbean Colombia, and coastal Venezuela were sequenced and together with published sequences (Paraguay) provided context for interpretation. A total of six ITS1 sequence variants were recognized in the Andean region comprising four groups. Type I predominates in the southernmost range of Anastrepha fraterculus. Type II predominates in its northernmost range. In the central and northern Andes, the geographic distributions overlap and interdigitate with a strong elevational effect. A discussion of relationships between observed ITS1 types and morphometric types is included. PMID:26798259

  4. Peculiar seismotectonic characteristics of Nazca's subducted slab, in the Andean region: Why do they exist?

    Science.gov (United States)

    Berrocal, J.; Fernandes, C.

    2007-05-01

    The peculiar morphology of Wadati-Benioff Zone (WBZ) beneath Andean region presents controversial seismotectonic characteristics of the subducting Nazca plate beneath South American plate: WBZ with an almost flat behaviour under Central-Northern Peru region, and beneath Central Chile region, intercalated with steeply portion of the slab; the almost completely aseismic portion between 300 and 500 km of depth; the existence of deep earthquakes in South American and their controversial focal mechanism. There are several hypotheses trying to explain a suitable origin for those deep earthquakes that occur in depths between 500 and almost 700 km, where the occurrence of brittle failure is improbable to exist due to the presence of high temperature and pressure conditions at those depths. We propose in this work - based mainly in the spatial distribution of relocated hypocentres, and in the joint interpretation with recent published results related to seismotectonic aspects of Andean region - a top-to- northwest shear of the portion of Nazca subducting plate between 24°S and 01°S, in such an amount that its deepest corresponding extremes, at around 600 km of depth, seem to be presently, under latitudes between 29°S and 06°S, respectively. The proposed northwestern displacement of South American plate may be provoking that shear process of Nazca slab, which should be larger at shallower depths of the slab, and limited to those latitudes below the Andean region. The NW displacement of Nazca slab could explain the existence of flat subduction beneath Central-Northern Peru region as a consequence of a probable northwards migration of the buoyant Nazca ridge after subduction under South American plate in around 15°S. Similar explanation could be used for the flat WBZ beneath Central Chile and the Juan Fernandez ridge. This hypothesis permits to infer for some very deep South American earthquakes shear, planar mechanisms at high pressure, some times as almost horizontal

  5. Molecular characterization of the Andean blackberry, Rubus glaucus, using SSR markers.

    Science.gov (United States)

    Marulanda, M; López, A M; Uribe, M

    2012-01-01

    The species Rubus glaucus, also known as the Andean or "Castilla" blackberry, is one of nine edible species of this genus that grow naturally in Central and South America. In Colombia, this species is the most important of all Rubus species for agricultural and commercial purposes. We used 20 SSRs developed for other Rubus species to characterize 44 Colombian R. glaucus genotypes, collected from eight different departments, and to look for molecular differences between thornless and thorny cultivated blackberries. Eighty-two bands were obtained from 28 loci. The genotypes were classified into eight populations, corresponding to collection sites. The mean number of polymorphic alleles per locus in all populations and genotypes ranged from 1.857 to 2.393. Samples collected from Valle del Cauca, Quindío, Caldas, and Risaralda departments had the highest heterozygosity values. The finding of exclusive bands from R. glaucus genotypes from Valle del Cauca, Quindío, and Caldas demonstrates genetic and molecular differentiation between thorny and thornless Andean blackberries. PMID:22370934

  6. Análisis de las características geométricas y desarrollo temporal de un sistema de díaclasas en las rocas triásicas del límite Cordillera Ibérica - Sistema Central

    OpenAIRE

    Sevillano, Ana; Gutiérrez Alonso, Gabriel; Gross, M.R.

    2000-01-01

    The mesozoic and tertiary rocks at the Iberian Range-Spanish Central System boundary in Guadalajara (Spain) depict a very important development of systematic joint sets. This study is focused on a detailed and systematic analysis of the orientations and lengths of the joints, and the relationship between both geometric parameters in two well exposed outcrops called Atance 1 and Atance 2. Both outcrops are located on two nearly horizontal beds of Muschelkalk dolomites and have been mapped in g...

  7. Andean grasslands are as productive as tropical cloud forests

    NARCIS (Netherlands)

    Oliveras Menor, I.; Girardin, C.; Doughty, C.E.; Cahuana, N.; Arenas, C.E.; Oliver, V.; Huaraca Huasco, W.; Malhi, Y.

    2014-01-01

    We aim to assess net primary productivity (NPP) and carbon cycling in Andean tropical alpine grasslands (puna) and compare it with NPP of tropical montane cloud forests. We ask the following questions: (1) how do NPP and soil respiration of grasslands vary over the seasonal cycle? (2) how do burning

  8. Andean shrublands of Moquegua, South Peru: Prepuna plant communities

    NARCIS (Netherlands)

    Montesinos, D.B.; Cleef, A.M.; Sykora, K.V.

    2012-01-01

    A syntaxonomic overview of shrubland vegetation in the southern Andean regions of Peru is presented. For each plant community, information is given on physiognomy, floristic diversity, ecology and geographical distribution. The shrub vegetation on the slopes of the upper Tambo river valley includes

  9. The Andean Common Market: An Experiment in Regional Cooperation.

    Science.gov (United States)

    Carlson, Reynold E.

    The Grupo Andino (GRAN) was formed in 1969 as an effort at economic integration by six Latin American countries (Bolivia, Chile, Columbia, Ecuador, Peru, and Venezuela). It was an outgrowth of its predecessor, the Latin American Free Trade Association (LAFTA), which had been formed in 1960 with eleven member countries. The Andean Group (GRAN) from…

  10. Predicting Polylepis distribution: vulnerable and increasingly important Andean woodlands

    OpenAIRE

    Brian R. Zutta; Phillip W. Rundel; Sassan Saatchi; Jorge D. Casana; Paul Gauthier Gauthier; Aldo Soto; Yessenia Velazco; Wolfgang Buermann

    2012-01-01

    Polylepis woodlands are a vital resource for preserving biodiversity and hydrological functions, which will be altered by climate change and challenge the sustainability of local human communities. However, these highaltitude Andean ecosystems are becoming increasingly vulnerable due to anthropogenic pressure including fragmentation, deforestation and the increase in livestock. Predicting the distribution of native woodlands has become increasingly important to counteract the negative effects...

  11. Climate change variability and Andean agriculture: The context

    OpenAIRE

    Valdivia, Corinne

    2008-01-01

    A presentation by Valdivia from lessons learned in the SANREM CRSP and past research to frame the two day workshop. First session of the workshop: I. Climate Change Variability and Andean Agriculture: The Context Lessons learned from SANREM CRSP on adapting to climate change. LTRA-4 (Practices and Strategies for Vulnerable Agro-Ecosystems)

  12. Active rollback in the Gibraltar Arc: Evidences from CGPS data in the western Betic Cordillera

    Science.gov (United States)

    Gonzalez-Castillo, L.; Galindo-Zaldivar, J.; de Lacy, M. C.; Borque, M. J.; Martinez-Moreno, F. J.; García-Armenteros, J. A.; Gil, A. J.

    2015-11-01

    The Gibraltar Arc, located in the western Mediterranean Sea, is an arcuate Alpine orogen formed by the Betic and Rif Cordilleras, separated by the Alboran Sea. New continuous GPS data (2008-2013) obtained in the Topo-Iberia stations of the western Betic Cordillera allow us to improve the present-day deformation pattern related to active tectonics in this collision area between the Eurasian and African plates. These data indicate a very consistent westward motion of the Betic Cordillera with respect to the relatively stable Iberian Massif foreland. The displacement in the Betics increases toward the south and west, reaching maximum values in the Gibraltar Strait area (4.27 mm/yr in Ceuta, CEU1, and 4.06 mm/yr in San Fernando, SFER), then progressively decreasing toward the northwestern mountain front. The recent geological structures and seismicity evidence moderate deformation in a roughly NW-SE to WNW-ESE compressional stress setting in the mountain frontal areas, and moderate extension toward the internal part of the cordillera. The mountain front undergoes progressive development of folds affecting at least up to Pliocene deposits, with similar recent geological and geodetical rates. This folded strip helps to accommodate the active deformation with scarce associated seismicity. The displacement pattern is in agreement with the present-day clockwise rotation of the tectonic units in the northern branch of the Gibraltar Arc. Our data support that the westward emplacement of the Betic Cordillera continues to be active in a rollback tectonic scenario.

  13. 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

  14. Lizards on ice: evidence for multiple refugia in Liolaemus pictus (Liolaemidae during the last glacial maximum in the Southern Andean beech forests.

    Directory of Open Access Journals (Sweden)

    Iván Vera-Escalona

    Full Text Available Historical climate changes and orogenesis are two important factors that have shaped intraspecific biodiversity patterns worldwide. Although southern South America has experienced such complex events, there is a paucity of studies examining the effects on intraspecific diversification in this part of the world. Liolaemus pictus is the southernmost distributed lizard in the Chilean temperate forest, whose genetic structure has likely been influenced by Pleistocene glaciations. We conducted a phylogeographic study of L. pictus in Chile and Argentina based on one mitochondrial and two nuclear genes recovering two strongly divergent groups, Northern and Southern clades. The first group is distributed from the northernmost limit of the species to the Araucanía region while the second group is distributed throughout the Andes and the Chiloé archipelago in Southern Chile. Our results suggest that L. pictus originated 751 Kya, with divergence between the two clades occurring in the late Pleistocene. Demographic reconstructions for the Northern and Southern clades indicate a decrease in effective population sizes likely associated with Pleistocene glaciations. Surprisingly, patterns of genetic variation, clades age and historical gene flow in populations distributed within the limits of the Last Glacial Maximum (LGM are not explained by recent colonization. We propose an "intra-Andean multiple refuge" hypothesis, along with the classical refuge hypothesis previously proposed for the biota of the Chilean Coastal range and Eastern Andean Cordillera. Our hypothesis is supported by niche modelling analysis suggesting the persistence of fragments of suitable habitat for the species within the limits of the LGM ice shield. This type of refuge hypothesis is proposed for the first time for an ectothermic species.

  15. How do subduction processes contribute to forearc Andean uplift? Insights from numerical models

    Science.gov (United States)

    Martinod, J.; Regard, V.; Letourmy, Y.; Henry, H.; Hassani, R.; Baratchart, S.; Carretier, S.

    2016-05-01

    We present numerical models to study how changes in the process of subduction may explain the observed Quaternary uplift of the Andean forearc region. Indeed, most segments of the South American Pacific coasts between 16 and 32° S have been uplifting since the Lower Pleistocene, following a period of stability of the forearc region. Models confirm that local uplift is expected to occur above ridges, this phenomenon being predominant in central Peru where the Nazca Ridge is subducting. We investigate the effects of slab pull, interplate friction and convergence velocity on the vertical displacements of the overriding plate. We propose that the global tendency to coastal uplift is accompanying the deceleration of the Nazca-South America convergence that occurred in the Pleistocene. In contrast, forearc subsidence may accompany increasing convergence velocities, as suggested by the subsidence history of the South America active margin.

  16. Pedological and mineralogical investigations on a soil-paleosoil sequence within Andosols in the Western Cordillera of the Peruvian Andes (region Laramate, 14.5S)

    Science.gov (United States)

    Leceta Gobitz, Fernando; Mächtle, Bertil; Schukraft, Gerd; Meyer, Hans-Peter; Eitel, Bernhard

    2016-04-01

    An integrated research project of environmental sciences focuses on a group of four Andosol profiles in Western flank of the Peruvian southern Andes. Aim of this study is to contribute to the reconstruction of the paleo environmental conditions in the Western Cordillera of the Peruvian Andes. Standard pedological and sedimentological analysis has been conducted in order to identify morphological and geochemical features generated by climatic variations during the middle and late Holocene. Though a provenance analysis of sediments, all potential lithological sources around the town of Laramate are being examined under the scanning electron microscope, in order to find significant mineralogical associations downward the soil-profile. Preliminary results reveal two edaphic cycles within a soil-paleo soil-sequence: a relative poor developed "Ah" topsoil, mostly composed by fine grain sediments, is underlain by a well preserved "2Ah" paleo soil; a "2Bwt" subsoil exhibits signs of alteration and clay translocation; parent material in slight weathered statement at "2C" culminates the sequence. Mineralogical analytical data supports the premise, that materials in the uppermost horizons are relatable to distal geological units of the Western and Eastern Cordillera, therefore also related to other described aeolian archives from the region: "Desert Margin Loess" at the Andean foot-zone and "Mixed Loess" in the Puna grassland. The amphibole varieties Actinolite, Mg-Hornblende and Edenite could be only distinguished within the soil sediments. The fluvial transport to its current position is excluded, insofar mentioned varieties stem from the granodiorites of Coastal Batholite (downstream the study area), and the vulcanites of the Anta und Andahuaylas Formation (eastward the continental divide). References: Eitel, B., et al. (2005). "Geoarchaeological evidence from desert loess in the Nazca-Palpa region, southern Peru : Palaeoenvironmental changes and their impact on Pre

  17. Investigation of a measles outbreak in Cordillera, Northern Philippines, 2013

    Science.gov (United States)

    Zapanta, Ma Justina; de los Reyes, Vikki Carr; Tayag, Enrique; Magpantay, Rio

    2016-01-01

    Introduction Measles is a highly infectious viral illness that remains one of the leading causes of death among children worldwide. In the Philippines, decreasing routine vaccination coverage from 2007 to 2011 led to local measles outbreaks. A team investigated a measles outbreak reported in Cordillera of the Philippines in May 2013. Methods Measles case data with symptom onset from 2 February to 27 May 2013 were obtained from official sources and verified on site. Data included age, sex, residential address, signs and symptoms and vaccination status. Active case-findings were also conducted for contacts of these cases. The living environments of the cases were investigated. A survey was conducted with the cases and caregivers to understand their knowledge and attitudes about measles. Results There were 50 measles cases identified with an age range from six months to 32 years (median: 16 years). Thirty-two were male (64%). Twenty (40%) were hospitalized with one death. Thirty-two (64%) cases were laboratory confirmed, and 36 (72%) received a single dose of measles vaccine. Overcrowded living environments were observed among many cases. The majority of respondents (46/48, 96%) knew about measles, but there were misconceptions about the cause of measles and how it can be prevented and managed. Conclusion This measles outbreak occurred in an area with low immunization coverage. Achieving 95% measles immunization coverage and strengthening routine immunization strategies to address high-risk populations are recommended. Also, we recommend health education campaigns to include components that address misconceptions about measles. PMID:27766180

  18. Investigation of a measles outbreak in Cordillera, northern Philippines, 2013

    Directory of Open Access Journals (Sweden)

    Paola Katrina Ching

    2016-07-01

    Full Text Available Introduction: Measles is a highly infectious viral illness that remains one of the leading causes of death among children worldwide. In the Philippines, decreasing routine vaccination coverage from 2007 to 2011 led to local measles outbreaks. A team investigated a measles outbreak reported in Cordillera of the Philippines in May 2013. Methods: Measles case data with symptom onset from 2 February to 27 May 2013 were obtained from official sources and verified on site. Data included age, sex, residential address, signs and symptoms and vaccination status. Active case-findings were also conducted for contacts of these cases. The living environments of the cases were investigated. A survey was conducted with the cases and caregivers to understand their knowledge and attitudes about measles. Results: There were 50 measles cases identified with an age range from six months to 32 years (median: 16 years. Thirty-two were male (64%. Twenty (40% were hospitalized with one death. Thirty-two (64% cases were laboratory confirmed, and 36 (72% received a single dose of measles vaccine. Overcrowded living environments were observed among many cases. The majority of respondents (46/48, 96% knew about measles, but there were misconceptions about the cause of measles and how it can be prevented and managed. Conclusion: This measles outbreak occurred in an area with low immunization coverage. Achieving 95% measles immunization coverage and strengthening routine immunization strategies to address high-risk populations are recommended. Also, we recommend health education campaigns to include components that address misconceptions about measles.

  19. Dynamic Paleogeography of the Jurassic Andean Basin: pattern of regression and general considerations on main features

    Directory of Open Access Journals (Sweden)

    J-C. Vicente

    2006-09-01

    Full Text Available Following examination of the evolution of the Jurassic Andean retroarc basin at a global scale for the Central Andes, this paper analyses the pattern of the regressive process, and discusses some general features concerning Andean Jurassic Paleogeography. The early Upper Jurassic regression obeys to an exactly reverse pattern as the one evidenced for the Lower Jurassic transgressive process. Sectors with late transgressions become those with early regressions while those with early transgressions show later regressions. This fact may indicate that the Norte Chico Isthmus (29°S to 30°30'S was a precociously emerged zone from the Bajocian. This carries again a split up between the Tarapacá and Aconcagua-Neuquén basins until their complete drying up in the Late Oxfordian following their restricted circulation. This evaporitic late stage presents great analogy with the Mediterranean «Messinian crisis» and gives evidence of a general tectonic and magmatic control on the straits. The local transgressions observed on the cratonic margin of the central part of these shrinking basins were due to shifting of water masses resulting from the regressive process on the northern and southern margins. Comparison between the main stages of transgression and regression allows some quantification concerning velocities of displacement of coastlines, specifically lengthwise. The permanence of paleogeographic and structural features over the time argues for an indisputable tectonic heritage. In the dynamic framework of this typical barred retroarc basin where arc magmatic activity has contributed considerably to variation on sediment supply and changing bathymetry of the seaways connecting with the Pacific Ocean, evidence for an assumed global eustatic cycle remains questionable or very subordinated.

  20. Foreland sedimentary record of Andean mountain building during advancing and retreating subduction

    Science.gov (United States)

    Horton, Brian K.

    2016-04-01

    As in many ocean-continent (Andean-type) convergent margins, the South American foreland has long-lived (>50-100 Myr) sedimentary records spanning not only protracted crustal shortening, but also periods of neutral to extensional stress conditions. A regional synthesis of Andean basin histories is complemented by new results from the Mesozoic Neuquén basin system and succeeding Cenozoic foreland system of west-central Argentina (34-36°S) showing (1) a Late Cretaceous shift from backarc extension to retroarc contraction and (2) an anomalous mid-Cenozoic (~40-20 Ma) phase of sustained nondeposition. New detrital zircon U-Pb geochronological results from Jurassic through Neogene clastic deposits constrain exhumation of the evolving Andean magmatic arc, retroarc thrust belt, foreland basement uplifts, and distal eastern craton. Abrupt changes in sediment provenance and distal-to-proximal depositional conditions can be reconciled with a complex Mesozoic-Cenozoic history of extension, post-extensional thermal subsidence, punctuated tectonic inversion involving thick- and thin-skinned shortening, alternating phases of erosion and rapid accumulation, and overlapping igneous activity. U-Pb age distributions define the depositional ages of several Cenozoic stratigraphic units and reveal a major late middle Eocene-earliest Miocene (~40-20 Ma) hiatus in the Malargüe foreland basin. This boundary marks an abrupt shift in depositional conditions and sediment sources, from Paleocene-middle Eocene distal fluviolacustrine deposition of sediments from far western volcanic sources (Andean magmatic arc) and subordinate eastern cratonic basement (Permian-Triassic Choiyoi igneous complex) to Miocene-Quaternary proximal fluvial and alluvial-fan deposition of sediments recycled from emerging western sources (Malargüe fold-thrust belt) of Mesozoic basin fill originally derived from basement and magmatic arc sources. Neogene eastward advance of the fold-thrust belt involved thick

  1. Cenozoic crustal shortening and thickening contributions to Andean orogenesis: Preliminary results from structural mapping in the southern Peruvian Andes

    Science.gov (United States)

    Perez, N.; Horton, B. K.

    2012-12-01

    Estimates of Cenozoic crustal shortening and thickening from the southern Peruvian Andes are necessary to address ongoing debates regarding growth of the Andes and Altiplano plateau. However, limited regional studies in southern Peru prevent accurate assessments of the structural contributions to high topography. This study provides new structural mapping along a >200 km transect spanning the northernmost Altiplano to Subandes at 13-15.5°S and fills the gap between existing central Peruvian and northern Bolivian studies. New stratigraphic data, fault relationships and fold orientations are used to create an updated geologic map and provide insights into the style, timing and magnitude of crustal deformation. Preliminary cross sections accompanying these map transects illustrate deformation style and provide first-order estimates of shortening. Further cross section analyses will be balanced and provide estimates of total crustal shortening and associated thickening in southern Peru. The study transect is subdivided into belts according to the age of exposed rocks and style of deformation. From west to east these belts include: Cretaceous strata dominated by tight folds, closely spaced faults and multiple detachments; Permo-Triassic strata dominated by thicker thrust sheets and fault-fold orientations departing from typical Andean trends; and Paleozoic rocks characterized by thick thrust sheets and deformation focused near major faults. The Cretaceous belt is composed of marine limestones and upward coarsening, siltstone to coarse sandstone progradational sequences. Disharmonic and detachment folds in the Cretaceous section demonstrate the importance of interbedded gypsum and mudstone layers. Fault relationships suggest local shortening during the Early Cretaceous. The Permo-Triassic belt is composed of thick Permian carbonates (Copacabana Formation) and interbedded sandstones, conglomerates and volcanics of the Mitu Formation. This study defines the orientation of

  2. mtDNA and Y-chromosome diversity in Aymaras and Quechuas from Bolivia: different stories and special genetic traits of the Andean Altiplano populations.

    Science.gov (United States)

    Gayà-Vidal, Magdalena; Moral, Pedro; Saenz-Ruales, Nancy; Gerbault, Pascale; Tonasso, Laure; Villena, Mercedes; Vasquez, René; Bravi, Claudio M; Dugoujon, Jean-Michel

    2011-06-01

    Two Bolivian samples belonging to the two main Andean linguistic groups (Aymaras and Quechuas) were studied for mtDNA and Y-chromosome uniparental markers to evaluate sex-specific differences and give new insights into the demographic processes of the Andean region. mtDNA-coding polymorphisms, HVI-HVII control regions, 17 Y-STRs, and three SNPs were typed in two well-defined populations with adequate size samples. The two Bolivian samples showed more genetic differences for the mtDNA than for the Y-chromosome. For the mtDNA, 81% of Aymaras and 61% of Quechuas presented haplogroup B2. Native American Y-chromosomes were found in 97% of Aymaras (89% hg Q1a3a and 11% hg Q1a3*) and 78% of Quechuas (100% hg Q1a3a). Our data revealed high diversity values in the two populations, in agreement with other Andean studies. The comparisons with the available literature for both sets of markers indicated that the central Andean area is relatively homogeneous. For mtDNA, the Aymaras seemed to have been more isolated throughout time, maintaining their genetic characteristics, while the Quechuas have been more permeable to the incorporation of female foreigners and Peruvian influences. On the other hand, male mobility would have been widespread across the Andean region according to the homogeneity found in the area. Particular genetic characteristics presented by both samples support a past common origin of the Altiplano populations in the ancient Aymara territory, with independent, although related histories, with Peruvian (Quechuas) populations.

  3. Geology and micromammals of the Serra-1 site (Tabernas Basin, Betic Cordillera

    Directory of Open Access Journals (Sweden)

    Ruiz Bustos, A.

    1993-12-01

    Full Text Available A chronology is given for the alluvial fan deposits in the Tabernas Basin (Internal Zone, Betic Cordillera. Palaeontological and sedimentological data are used to establish a palaeoclimatic model for the Quaternary in southeastern Spain.La Cuenca de Tabernas está situada en la zona interna de la Cordillera Bética, se da una cronología para los depósitos formados por abanicos aluviales y se plantea a través de datos paleontológicos y sedimentológicos un modelo paleochmátlco para el Cuaternano en el sureste de España.

  4. Nautiloideos del Triásico Medio en la Cordillera Ibérica y en la parte oriental de las Cordilleras Béticas

    OpenAIRE

    Goy Goy, A.; Martínez, G.

    1996-01-01

    [ES] En el presente trabajo se dan a conocer las sucesiones de los nautiloideos obtenidos en cada una de las cuencas estudiadas, así como sus implicaciones biocronoestratigráficas. En la parte oriental de las Cordilleras Béticas existe el siguiente registro de nautiloideos: — Grypoceras cf? privatum (MOJSISOVICS). Parte inferior del Muschelkalk en Quipar (Murcia). — Germanonautilus bidorsatus (SCHLOTI-{EIM); Mojsvaroceras cf? kummeli PARNES; fudonautifus cf? awadi KUMM...

  5. Climate Change Forces New Ecological States in Tropical Andean Lakes

    OpenAIRE

    Michelutti, Neal; Wolfe, Alexander P.; Cooke, Colin A.; Hobbs, William O.; Vuille, Mathias; John P. Smol

    2015-01-01

    Air temperatures in the tropical Andes have risen at an accelerated rate relative to the global average over recent decades. However, the effects of climate change on Andean lakes, which are vital to sustaining regional biodiversity and serve as an important water resource to local populations, remain largely unknown. Here, we show that recent climate changes have forced alpine lakes of the equatorial Andes towards new ecological and physical states, in close synchrony to the rapid shrinkage ...

  6. Climate change and tropical Andean glaciers : past, present and future

    OpenAIRE

    Vuille, M.; Francou, Bernard; Wagnon, Patrick; I. Juen; G. Kaser; Mark, B G; Bradley, R.S.

    2008-01-01

    Observations on glacier extent from Ecuador, Peru and Bolivia give a detailed and unequivocal account of rapid shrinkage of tropical Andean glaciers since the Little Ice Age (LIA). This retreat however, was not continuous but interrupted by several periods of stagnant or even advancing glaciers, most recently around the end of the 20th century. New data from mass balance networks established on over a dozen glaciers allows comparison of the glacier behavior in the inner and outer tropics. It ...

  7. Andean grasslands are as productive as tropical cloud forests

    OpenAIRE

    Oliveras Menor, I.; Girardin, C; Doughty, C. E.; Cahuana, N.; Arenas, C. E.; Oliver, V.; Huaraca Huasco, W.; Malhi, Y.

    2014-01-01

    We aim to assess net primary productivity (NPP) and carbon cycling in Andean tropical alpine grasslands (puna) and compare it with NPP of tropical montane cloud forests. We ask the following questions: (1) how do NPP and soil respiration of grasslands vary over the seasonal cycle? (2) how do burning and grazing affect puna productivity? (3) if the montane forest expands into the puna, what will be the resulting change in productivity? The study sites are located at the South-eastern Peruvian ...

  8. Genetic diversity and germplasm conservation of three minor Andean tuber crop species

    Directory of Open Access Journals (Sweden)

    Malice M.

    2009-01-01

    Full Text Available In traditional Andean agrosystems, three minor tuber crop species are of regional or local importance: oca (Oxalis tuberosa Molina, ulluco (Ullucus tuberosus Caldas and mashua (Tropaeolum tuberosum Ruiz and Pav.. Genetic diversity within these species is very large and could result from the high ecological and cultural variability that characterizes the Andean area. Nowadays, many anthropic or ecological factors cause the loss of diversity and contribute to genetic erosion. The development of conservation strategies for genetic resources of Andean tubers, in situ as well as ex situ, includes a better knowledge of diversity in addition to the study of Andean farming strategies linked to this genetic diversity.

  9. State dilemmas in applying the Previous Consultation Law in the Andean Region

    Directory of Open Access Journals (Sweden)

    Rafael Barrio de Mendoza

    2013-12-01

    Full Text Available The Peruvian government enacted a new law granting consultation rights to indigenous peoples as a mechanism to enhance social inclusion in the country. The law generated debates about the criteria to identify indigenous population in the Andean region. Why does this law have problems granting consultation rights to Andean people? This paper aims to answer the question by reviewing historically the different Andean identities and analyzing the current international debate on indigenity. Our main argument is that the government intrying to apply the law is structuring a restrictive model that is hardlyable to grasp the complexity and dynamism of Andean identities.

  10. Evaporite deposits of Bogota area, Cordillera Oriental, Colombia

    Science.gov (United States)

    McLaughlin, Donald H.

    1972-01-01

    Four evaporite-bearing stratigraphic zones are known in Cretaceous strata of the Cordillera Oriental of Colombia north and east of Bogota. The easternmost and oldest zone is probably of Berriasian to Valanginian age. The next oldest is probably late Barremian to early Aptian in age. The third appears to be Aptian. The westernmost and best known sequence in the Sabana de Bogota is Turonian to early Coniacian in age. This youngest sequence contains the thickest salt deposits known in Colombia and is probably the most widespread geographically. Most of the rock salt exposed in the three accessible mines (at Zipaquira, Nemocon, and Upin) has a characteristic lamination of alternating slightly argillaceous and highly argillaceous salt layers of varied but moderate thickness. Black, calcareous claystone, commonly very pyritic, is interbedded conformably with the laminated salt in many places throughout the deposits. Fragments of black claystone derived from the thinner interbeds are ubiquitous in all deposits, both as concordant breccia zones and as isolated clasts. Anhydrite is scarce at Zipaquira and apparently even rarer at Nemocon and Upin. Gypsum is produced at three small deposits in the oldest evaporite zone where it probably was concentrated by leaching of salt initially associated with it. The two intervening evaporite zones are not exposed, but their existence and distribution are indicated by brine springs and locally by "rute," a distinctive black, calcareous mud formed by the leaching of salt beds. Fossils show that the youngest salt-claystone zone, in the Sabana de Bogota, is contemporary with associated hematitic sandstone and siltstone, and with carbonaceous and locally coaly claystone. Although evidence is poor, this same facies relation probably exists within the other three evaporite zones. All salt deposits in this study probably are associated with anticlines, a relation best exemplified by the deposits on the Sabana de Bogota. Within these

  11. The role of changing geodynamics in the progressive contamination of Late Cretaceous to Late Miocene arc magmas in the southern Central Andes

    Science.gov (United States)

    Jones, Rosemary E.; Kirstein, Linda A.; Kasemann, Simone A.; Litvak, Vanesa D.; Poma, Stella; Alonso, Ricardo N.; Hinton, Richard

    2016-10-01

    The tectonic and geodynamic setting of the southern Central Andean convergent margin changed significantly between the Late Cretaceous and the Late Miocene, influencing magmatic activity and its geochemical composition. Here we investigate how these changes, which include changing slab-dip angle and convergence angles and rates, have influenced the contamination of the arc magmas with crustal material. Whole rock geochemical data for a suite of Late Cretaceous to Late Miocene arc rocks from the Pampean flat-slab segment (29-31 °S) of the southern Central Andes is presented alongside petrographic observations and high resolution age dating. In-situ U-Pb dating of magmatic zircon, combined with Ar-Ar dating of plagioclase, has led to an improved regional stratigraphy and provides an accurate temporal constraint for the geochemical data. A generally higher content of incompatible trace elements (e.g. Nb/Zr ratios from 0.019 to 0.083 and Nb/Yb from 1.5 to 16.4) is observed between the Late Cretaceous (~ 72 Ma), when the southern Central Andean margin is suggested to have been in extension, and the Miocene when the thickness of the continental crust increased and the angle of the subducting Nazca plate shallowed. Trace and rare earth element compositions obtained for the Late Cretaceous to Late Eocene arc magmatic rocks from the Principal Cordillera of Chile, combined with a lack of zircon inheritance, suggest limited assimilation of the overlying continental crust by arc magmas derived from the mantle wedge. A general increase in incompatible, fluid-mobile/immobile (e.g., Ba/Nb) and fluid-immobile/immobile (e.g., Nb/Zr) trace element ratios is attributed to the influence of the subducting slab on the melt source region and/or the influx of asthenospheric mantle. The Late Oligocene (~ 26 Ma) to Early Miocene (~ 17 Ma), and Late Miocene (~ 6 Ma) arc magmatic rocks present in the Frontal Cordillera show evidence for the bulk assimilation of the Permian-Triassic (P

  12. Elevation-dependent changes in n-alkane δD and soil GDGTs across the South Central Andes

    Science.gov (United States)

    Nieto-Moreno, Vanesa; Rohrmann, Alexander; van der Meer, Marcel T. J.; Sinninghe Damsté, Jaap S.; Sachse, Dirk; Tofelde, Stefanie; Niedermeyer, Eva M.; Strecker, Manfred R.; Mulch, Andreas

    2016-11-01

    Surface uplift of large plateaus may significantly influence regional climate and more specifically precipitation patterns and temperature, sometimes complicating paleoaltimetry interpretations. Thus, understanding the topographic evolution of tectonically active mountain belts benefits from continued development of reliable proxies to reduce uncertainties in paleoaltimetry reconstructions. Lipid biomarker-based proxies provide a novel approach to stable isotope paleoaltimetry and complement authigenic or pedogenic mineral proxy materials, in particular outside semi-arid climate zones where soil carbonates are not abundant but (soil) organic matter has a high preservation potential. Here we present δD values of soil-derived n-alkanes and mean annual air temperature (MAT) estimates based on branched glycerol dialkyl glycerol tetraether (brGDGT) distributions to assess their potential for paleoelevation reconstructions in the southern central Andes. We analyzed soil samples across two environmental and hydrological gradients that include a hillslope (26-28°S) and a valley (22-24°S) transect on the windward flanks of Central Andean Eastern Cordillera in NW Argentina. Our results show that present-day n-alkane δD values and brGDGT-based MAT estimates are both linearly related with elevation and in good agreement with present-day climate conditions. Soil n-alkanes show a δD lapse rate (Δ (δD)) of - 1.64 ‰ / 100 m (R2 = 0.91, p < 0.01) at the hillslope transect, within the range of δD lapse rates from precipitation and surface waters in other tropical regions in the Andes like the Eastern Cordillera in Colombia and Bolivia and the Equatorial and Peruvian Andes. BrGDGT-derived soil temperatures are similar to monitored winter temperatures in the region and show a lapse rate of ΔT = - 0.51 °C / 100 m (R2 = 0.91, p < 0.01), comparable with lapse rates from in situ soil temperature measurements, satellite-derived land-surface temperatures at this transect, and

  13. Erosion of particulate organic material from an Andean river and its delivery to the Amazon Basin

    Science.gov (United States)

    Clark, Kathryn; Hilton, Robert; West, A. Joshua; Robles Caceres, Arturo; Grocke, Darren; Marthews, Toby; Asner, Greg; New, Mark; Mahli, Yadvinder

    2016-04-01

    Organic carbon and nutrients discharged by mountainous rivers can play an important role in biogeochemical cycles from regional to global scales. The eastern Andes host productive forests on steep, rapidly eroding slopes, a combination that is primed to deliver sediment, carbon and nutrients to the lowland Amazon River. We quantify clastic sediment and particulate organic carbon (POC) discharge for the Kosñipata River, Peru, an Andean tributary of the Madre de Dios River, using suspended sediment samples and discharge measurements over one year at two gauging stations. Calculations of sediment yield on the basis of this data suggest that the Madre de Dios basin may have erosion rates ˜10 times greater than the Amazon Basin average. The total POC yield over the sampling period was up to five times higher than the yield in the lowland Amazon Basin, with most POC (70-80%) exported between December and March in the wet season. We use radiocarbon, stable C isotopes and C/N ratios to distinguish between the erosion and discharge of POC from sedimentary rocks (petrogenic POC) and POC eroded from the modern terrestrial biosphere, from vegetation and soil (biospheric POC). We find that biospheric POC discharge was significantly enhanced during flood events, over that of clastic sediment and petrogenic POC. The ultimate fate of the eroded POC may play a central role in the net carbon budget of Andean forest. In these forests, net productivity minus heterotrophic respiration is close to zero at the scale of forest plots, and the erosion of biospheric POC by this Andean river is sufficiently rapid that its fate downstream (sedimentary burial/preservation versus oxidation/degradation) may determine whether the mountain forest is a carbon sink or source to the atmosphere. In addition, the measured discharge of petrogenic POC suggests that fluxes from the Andes may be considerably higher than measured downstream in the Madeira River. If this petrogenic POC is oxidised rather

  14. Integración regional andina en salud Health in Andean regional integration

    Directory of Open Access Journals (Sweden)

    Carlos A. Agudelo

    2007-01-01

    Full Text Available A pesar su historia compartida, los países de la Región Andina presentan una diversidad social y política que genera realidades sanitarias heterogéneas y procesos de integración complejos. Se han dado por décadas procesos generales, como la Asociación Latinoamericana de Libre Comercio y la Asociación Latinoamericana de Integración, o de alcance regional como la Comunidad Andina de Naciones, la Comunidad del Caribe y el Mercado Común Centroamericano. En el campo específico de la salud se cuenta con un instrumento en la Región Andina, el Convenio Hipólito Unánue, creado en 1971. Estos procesos de integración se han concentrado en los aspectos económicos, con base en acuerdos de preferencias arancelarias, los cuales han generado, en el largo plazo, un intercambio comercial apreciable. En el campo de la salud se ha avanzado menos, en términos de procesos que ponen en común experiencias nacionales, conocimientos y capacidades. El análisis de las experiencias de integración en salud muestra que esta depende de las fortalezas de cada país y, en gran parte, de los procesos políticos nacionales.Despite their shared history, the Andean countries are socially and politically diverse, with heterogeneous health realities and complex integration processes. General developments such as the Latin American Free Trade Association and Latin American Integration Association have existed for decades, along with others of a regional scope, like the Andean Community of Nations, Caribbean Community, and Central American Common Market. The health field has a specific instrument in the Andean Region called the Hipólito Unánue Agreement, created in 1971. Integration processes have concentrated on economic aspects, based on preferential customs agreements that have led to an important long-term increase in trade. Less progress has been made in the field of health in terms of sharing national experiences, knowledge, and capabilities. Analysis of

  15. The time-space distribution of Eocene to Miocene magmatism in the central Peruvian polymetallic province and its metallogenetic implications

    Science.gov (United States)

    Bissig, Thomas; Ullrich, Thomas D.; Tosdal, Richard M.; Friedman, Richard; Ebert, Shane

    2008-07-01

    Eocene to late Miocene magmatism in the central Peruvian high-plain (approx. between Cerro de Pasco and Huancayo; Lats. ˜10.2-12°S) and east of the Cordillera Occidental is represented by scattered shallow-level intrusions as well as subaerial domes and volcanic deposits. These igneous rocks are calc-alkalic and range from basalt to rhyolite in composition, and many of them are spatially, temporally and, by inference, genetically associated with varied styles of major polymetallic mineralization. Forty-four new 40Ar- 39Ar and three U/Pb zircon dates are presented, many for previously undated intrusions. Our new time constraints together with data from the literature now cover most of the Cenozoic igneous rocks of this Andean segment and provide foundation for geodynamic and metallogenetic research. The oldest Cenozoic bodies are of Eocene age and include dacitic domes to the west of Cerro de Pasco with ages ranging from 38.5 to 33.5 Ma. South of the Domo de Yauli structural dome, Eocene igneous rocks occur some 15 km east of the Cordillera Occidental and include a 39.34 ± 0.28 Ma granodioritic intrusion and a 40.14 ± 0.61 Ma rhyolite sill, whereas several diorite stocks were emplaced between 36 and 33 Ma. Eocene mineralization is restricted to the Quicay high-sulfidation epithermal deposit some 10 km to the west of Cerro de Pasco. Igneous activity in the earliest Oligocene was concentrated up to 70 km east of the Cordillera Occidental and is represented by a number of granodioritic intrusions in the Milpo-Atacocha area. Relatively voluminous early Oligocene dacitic to andesitic volcanism gave rise to the Astabamba Formation to the southeast of Domo de Yauli. Some stocks at Milpo and Atacocha generated important Zn-Pb (-Ag) skarn mineralization. After about 29.3 Ma, magmatism ceased throughout the study region. Late Oligocene igneous activity was restricted to andesitic and dacitic volcanic deposits and intrusions around Uchucchacua (approx. 25 Ma) and felsic

  16. Palynology of cushion bogs of the Cordillera Pelada, Province of Valdivia, Chile

    Science.gov (United States)

    Heusser, Calvin J.

    1982-01-01

    Fossil pollen identified in the earliest sediments of three cushion bogs in the Cordillera Pelada (40°10'S, 73°30'W) dated 10,425 14C yr B.P. includes the subantarctic species Dacrydium fonckii, Tetroncium magellanicum, Astelia pumila, Gaimardia australis, Donatia fascicularis, and Drosera uniflora. All grow today in the Cordillera Pelada and range poleward to the southernmost Province of Magallanes; one species, Drapetes muscosa, included with the pollen of these plants in the earliest record, is no longer a constituent of the flora but is limited only to subantarctic Chile. Available evidence indicates that plants survived the last glaciation north of the glacial border with the course of postglacial migration southward following the wastage of the glacier complex. Holocene climatic and vegetational changes in the Cordillera Pelada are interpreted in the context of regional reconstructions which show maximum warmth about 9000 yr ago with a pronounced dry period lasting from 9000 to 6500 yr B.P. Maximum precipitation was later reached around 4000 yr ago but has decreased overall since then. The regional decline of the endemic gymnosperm Fitzroya cupressoides, which today is extensively destroyed in the Cordillera Pelada, follows this decrease in precipitation. These climatic data suggest a net south ward shift in the zone of westerly winds that bring rainfall to the region over the past 4000 yr.

  17. GPS velocities and the construction of the Eastern Cordillera of the Colombian Andes

    Science.gov (United States)

    Mora-Páez, Héctor; Mencin, David J.; Molnar, Peter; Diederix, Hans; Cardona-Piedrahita, Leonardo; Peláez-Gaviria, Juan-Ramón; Corchuelo-Cuervo, Yuli

    2016-08-01

    GPS velocities across the northeast trending Eastern Cordillera of Colombia show oblique convergence at 8.8 ± 1.7 mm/yr, consisting of 8.0 ± 1.7 mm/yr of right-lateral strike-slip shear along the mountain range and 3.7 ± 0.3 mm/yr of northwest southeast shortening. Faster convergence occurs only at the northeast end of the Cordillera, where its eastern edge trends northwest and the highest mountains lie. The strike-slip shear corroborates geologic work suggesting such movement southwest and northeast of the range. Given the ~200 km width of the Eastern Cordillera, the ~100-150 km of crustal shortening inferred from balanced cross sections and implied by recent estimates of crustal thickness would require ~25-40 Myr of shortening at ~4 mm/yr. The present-day GPS measurements, therefore, are inconsistent with the inference, based on paleobotanical observations that the entire Eastern Cordillera rose 1500-2500 m since 3-6 Ma and called for a different interpretation of those data.

  18. Uptake of Hg2+ by picocyanobacteria in natural water from four Andean lakes

    Directory of Open Access Journals (Sweden)

    Diéguez M.C.

    2014-07-01

    Full Text Available In lake food webs, planktonic bacteria and algae represent the greatest bioconcentration step for Hg2+ and monomethyl-Hg (MeHg. As they are the most abundant organisms in planktonic trophic webs and also the main food resource for herbivorous plankton, they can mobilize large amounts of Hg to higher trophic levels. In Andean Patagonian lakes (Argentina, dissolved organic matter (DOM concentration and character, coupled with photo-reactions, play a central role in the complexation of Hg2+ in the water column and can even regulate the uptake of Hg2+ by planktonic algae. In this investigation we evaluated the DOM character of natural waters (NW from four Andean lakes and studied its influence on the uptake of 197Hg2+ in a strain of the picocyanobacteria Synechococcus by using Hg2+ labeled with 197Hg2+. The uptake of radiolabeled Hg2+ by Synechococcus showed different magnitude in NW of lakes Moreno, El Trébol, Morenito and Escondido. Increasing lake DOM concentration reduced the bioavailability of Hg2+ as indicated by the lower uptakes rates found in NW with higher complexity and concentration of the DOM pool. Uptakes of Hg2+ by this picocyanobacteria contrasted among NW from pelagic (surface and bottom and littoral compartments of Lake Escondido which suggest that the entry of this metal may be highly variable even in the same environment. The study of the uptake of radiolabeled Hg2+ in a set of dilutions of NW from Lake Escondido demonstrated that the bioavailability of Hg2+ decrease with increasing DOM concentration.

  19. Can cosmic ray exposure dating reveal the normal faulting activity of the Cordillera Blanca Fault, Peru? ¿Dataciones por exposición de rayos cósmicos revelan fallamiento activo normal en la falla de la Cordillera Blanca, Perú?

    Directory of Open Access Journals (Sweden)

    L.L. Siame

    2006-12-01

    Full Text Available The build-up of in situ-produced cosmogenic 10Be within bedrock scarps and escarpments associated to the Cordillera Blanca Normal Fault, Peru, was measured to evaluate, through Cosmic Ray Exposure dating, its normal faulting activity. The highest mountain peaks in Peru belong to the 210 km-long, NW- striking, Cordillera Blanca. Along its western border, the Cordillera Blanca Normal Fault is responsible for a vertical relief over 4.4 km, whose prominent 2 km high escarpment is characterized by ~1 km-high triangular facets corresponding to vertical displacements cumulated during the last 1-2 million years. At a more detailed scale, this fault system exhibits continuous geomorphic evidence of repeated displacements, underlined by 2 to 70 m-high scarps, corresponding to vertical displacements cumulated since Late Pleistocene and Holocene periods. Although microseismicity occurs along the Cordillera Blanca Normal Fault, no major historical or instrumental earthquake has been recorded since the beginning of the Spanish settlement in the 16th century. To evaluate the vertical slip rate along the major 90 km-long central segment of the Cordillera Blanca Normal Fault, the Quaternary fault escarpment (i.e., triangular facet, as well as the bedrock fault scarp, have been sampled for 10Be Cosmic Ray Exposure dating. Even if the uppermost part of the triangular facets have been resurfaced by the Last Glacial Maximum glaciers, our results allow to estimate a vertical slip-rate of 3±1 mm/yr, and suggest at least 2 seismic events during the last 3000 years.La acumulación in situ de 10Be cosmogénico en las rocas intrusivas de las escarpas de la falla normal de la Cordillera Blanca del Perú han sido medidas para evaluar, su actividad de fallamiento normal., con edades de exposición a los rayos cósmicos. Los más altos picos en el Perú conforman la Cordillera Blanca que se extiende con una longitud de 210 km según una orientación NO. A lo largo de su l

  20. Tomographic images of subducted oceans matched to the accretionary records of orogens - Case study of North America and relevance to Central Asia

    Science.gov (United States)

    Sigloch, Karin; Mihalynuk, Mitchell G.; Hosseini, Kasra

    2016-04-01

    Accretionary orogens are the surface record of subduction on the 100-million-year timescale; they aggregate buoyant crustal welts that resisted subduction. The other record of subduction is found in the deep subsurface: oceanic lithosphere preserved in the mantle that records ocean basin closure between successive generations of arcs. Seismic tomography maps out these crumpled paleo-oceans down to the core-mantle boundary, where slab accumulates. One such accumulation of enormous scale is under Eastern Asia, recording the assembly of the Central Asian Orogenic Belt (CAOB). Deep CAOB slab has hardly been explored because tomographic image resolution in the lowermost mantle is limited, but this is rapidly improving. We present new images of the CAOB slabs from our P-wave tomography that includes core-diffracted waves as a technical novelty. The previous slab blur sharpens into the type of elongated geometries expected to trace paleo-trench lines. Since the North American Cordillera is younger than the CAOB (mostly 10,000 km long. North America converged on the two microcontinents by westward subduction of two intervening basins (which we name Mezcalera and Angayucham oceans), culminating in diachronous suturing between ~150 Ma and ~50 Ma. Hence geophysical subsurface evidence negates the widely accepted "Andean-style" model of Farallon-beneath-continent subduction since at least 180 Ma, and supports a Jura-Cretaceous paleogeography closer to today's Southwestern Pacific, or to the Paleozoic CAOB. Though advocated since the 1970's by a minority of geologists, this scenario had not gained wide acceptance due to a record obscured by overprinting, margin-parallel translation, and oroclinal bending. The new subsurface evidence provides specific indications where to seek the decisive Mezcalera-Angayucham suture. The suture is evident in a trail of collapsed Jura-Cretaceous basin relics that run the length of the Cordillera. Reference: Sigloch, K., & Mihalynuk, M. G. (2013

  1. 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...

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

    Science.gov (United States)

    Arriagada, C. A.

    2013-05-01

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

  3. 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

    wavelet analysis, we found an important 8-10 day cycle related to but lagging convective surges in the Amazon basin and enhanced upper-level cyclonic flow around the Bolivian High. The majority of the organized convection in the region tended to be weak (< 5 mm/hr rain rates) and shallow (< 12 km). The timing of response (i.e., formation and distribution of organized convection) due to changes in moisture transport around the Bolivian High was similar in the wetter eastern and drier western cordilleras of the Central Andes. The response to upper level moisture transport was modulated by local soil moisture and elevation slope and aspect, with higher elevation, eastern facing peaks having a stronger response than western-facing and lower elevation areas. Streamflow data support the hypothesis that the majority of the light rainfall infiltrates the shallow sub-surface, rather than contributing to surface channel runoff, helping to sustain the high altitude peatlands in the Andean valleys.

  4. Helium isotope characteristics of Andean geothermal fluids and lavas

    Science.gov (United States)

    Hilton, D. R.; Hammerschmidt, K.; Teufel, S.; Friedrichsen, H.

    1993-12-01

    The first comprehensive helium isotope survey of the Andes is reported here. We have sampled geothermal fluids and phyric lava flows from the Southern (svz) and Central (cvz) Volcanic Zones, the volcanically active Puna region and the Precordillera, Salta Basin, Longitudinal Valley and the aseismic region between the two volcanic zones. Although the active areas are characterized by significant differences in crustal age and thickness, the svz, cvz and Puna are characterized by a wide and overlapping range in He-3/He-4 ratios (for fluids and phenocrysts) from predominantly radiogenic values to close to the Mid-Ocean Ridge Basalt (MORB) ratio. The measured ranges in He-3/He-4 ratios (R) (reported normalised to the air He-3/He-4 -- R(sub A)) are: svz (0.18 less than R/R(sub A) less than 6.9); cvz (0.82 less than R/R(sub A) less than 6.0); and Puna (1.8 less than R/R(sub A) less than 5.4). Modification of magmatic He-3/He-4 ratios by water/rock interactions (fluids) or post-eruptive grow-in of radiogenic He-4 or preferential diffusive loss of He-3 (phenocrysts) is considered unlikely; this means that the wide range reflects the helium isotope characteristics of magma bodies in the Andean crust. The mechanism controlling the He-3/He-4 ratios appears to be a mixing between mantle (MORB-like) helium and a radiogenic helium component derived from radioactive decay within the magma (magma aging) and/or interaction with He-4-rich country rock: a process expected to be influenced by pre-eruptive degassing of the mantle component. Assimilation of lower crust is also capable of modifying He-3/He-4 ratios, albeit to a much lesser extent. However, it is possible that the highest measured values in each zone were established by the addition of lower crustal radiogenic helium to MORB helium. In this case, the higher 'base level' ratios of the svz would reflect the younger crustal structure of this region. In contrast to helium, there is no overlap in the Sr or Pb isotope

  5. 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

  6. Cenozoic back-arc magmatism of the southern extra-Andean Patagonia (44° 30' - 52° S: A review of geochemical data and geodynamic interpretations Magmatismo de retroarco cenozoico de la Patagonia extra-andina austral (44° 30' - 52° S: Una revisión de los datos geoquímicos e interpretaciones geodinámicas

    Directory of Open Access Journals (Sweden)

    M. D'Orazio

    2004-12-01

    Full Text Available Huge amounts of basaltic s.l. lavas were persistently erupted along the eastern side of the Andean Cordillera, throughout Cenozoic time, forming extensive plateaus, hundreds of monogenetic scoria cones and other volcanic structures in a continental back-arc setting. The igneous products exposed in the southern sector of the extra-Andean Patagonia (44° 30' - 52° S are dominantly mafic with minor slightly evolved compositions and rare highly differentiated products. The many published chemical analyses of these rocks, indicate that the mafic lavas range from strongly silica - undersaturated basanites to oversaturated basaltic andesites, and that most of the lavas have a typical within-plate geochemical signature. However, a number of lavas, generally erupted in the western-central sectors of Patagonia, are characterized by different distributions of the incompatible elements with high LILE/HFSE and LREE/HFSE ratios. The REE distribution modelling suggests a low degree of melting of a deep (> 70 km garnet-bearing source for the alkaline magmas, and a higher degree of melting of the same source, or an even higher degree of melting of an enriched source, for the subalkaline magmas. The available Sr-Nd-Pb isotope compositions clearly attest to a major geographic variation: the southernmost lavas have lower 87Sr/86Sr and higher 143Nd/144Nd and 206Pb/204Pb ratios with respect to those erupted to the north. On the whole, the Sr-Nd-Pb isotope compositions of the southern Patagonia lavas fall within the typical range of within-plate continental magmas; in addition the Pb isotope ratios fall in the range of the Southern Hemisphere Dupal Pb isotope anomaly. The geochemical variations of the southern Patagonia lavas are discussed in terms of different geochemical components: depleted and enriched sub-slab asthenosphere, enriched continental lithospheric mantle, continental crust and subducted materials. The geodynamic significance is interpreted with in the

  7. NEW GEOLOGICAL AND GEOPHYSICAL CONTRIBUTIONS IN THE SECTION IBAGUÉ – ARMENIA, CENTRAL CORDILLERA - COLOMBIA

    Directory of Open Access Journals (Sweden)

    Vargas Carlos A.

    2005-08-01

    Full Text Available Ha sido interpretada la sección geológica entre las ciudades de Ibagué y Armenia basada en observaciones geofísicas y estructurales en busca de establecer el estilo estructural dominante y la configuración del basamento en profundidad. Inicialmente se realizaron mediciones gravimétricas y magnetométricas levantadas cada 500 m entre estas ciudades, las cuales permitieron soportar el desarrollo del experimento sísmico "Armenia-Quake". El alcance del experimento sísmico permitió detectar reflectores hasta aproximadamente 17 km de profundidad en un área de influencia de aproximadamente 25 km. La interpretación integral de la información geológica y geofísica permite concluir que el Complejo Cajamarca define una estructura sinclinal amplia cerca al Municipio de Cajamarca. Partiendo de dicha información se pudo reconocer la presencia de un basamento compuesto por cuñas de rocas basálticas y sedimentarias asociadas a las formaciones Quebradagrande y Arquía. Igualmente se reconoce la existencia de una gran flexión de la paleo-placa oceánica relacionada a la formación Barroso, la cual se encuentra limitada al occidente por la falla Cauca-Almaguer. La estructura en flexión y la evolución compresiva del estado de esfuerzos en esta región de América del Sur podrían ser las responsables del depósito y posterior plegamiento de la formación Cinta de Piedra que constituye en gran medida la Serranía de Santa Bárbara.

  8. [Biomass recovery through secondary succession in the Cordillera Central de los Andes, Colombia].

    Science.gov (United States)

    del Valle, Jorge Ignacio; Restrepo, Héctor Iván; Londoño, Mónica María

    2011-09-01

    Estimations on biomass recovery rates by secondary tropical forests are needed to understand the complex tropical succession, and their importance on CO2 capture, to offset the warming of the planet. We conducted the study in the Porce River Canyon between 550 and 1 700m.a.s.l. covering tropical and premontane moist belts. We established 33 temporary plots of 50m x 20m in secondary forests, including fallows to succesional forests, and ranging between 3 and 36 years old; we measured the diameter at breast height (D) of all woody plants with D > or = 5cm. In each one of these plots we established five 10m x 10m subplots, in which we measured the diameter betweem 1cm woody plants. We estimated the biomass of pastures by harvesting 54 plots of 2m x 2m, and of shrubs in the fallows by harvesting the biomass in 18 plots of 5m x 2m. We modeled Bav (above ground live biomass of woody plants) and Brg (coarse root biomass) as a function of succesional age (t) with the growth model of von Bertalanffy, using 247t/ha and 66t/ha as asymptote, respectively. Besides, we modeled the ratios brg/bav = f(D) and Brg/Bav = f(t). The model estimated that 87 years are required to recover the existing Bav of primary forests through secondary succession, and 217 years for the Brg of the primary forest. The maximum instantaneous growth rate of the Bav was 6.95 t/ha/yr at age 10. The maximum average growth rate of the Bav was 6.26 t/ha/yr at age 17. The weighted average of the absolute growth rate of the Bav reached 4.57t/ha/yr and the relative growth rate 10% annually. The ratio brg/bav decreases with increasing D. The ratio Brg/Bav initially increases very rapidly until age 5 (25%), then decreases to reach 25 years (18%) and increases afterwards until the ratio reaches the asymptote (26.7%). PMID:22017137

  9. Regional Analysis of the Hazard Level of Glacial Lakes in the Cordillera Blanca, Peru

    Science.gov (United States)

    Chisolm, Rachel E.; Jhon Sanchez Leon, Walter; McKinney, Daene C.; Cochachin Rapre, Alejo

    2016-04-01

    The Cordillera Blanca mountain range is the highest in Peru and contains many of the world's tropical glaciers. This region is severely impacted by climate change causing accelerated glacier retreat. Secondary impacts of climate change on glacier retreat include stress on water resources and the risk of glacial lake outburst floods (GLOFs) from the many lakes that are forming and growing at the base of glaciers. A number of GLOFs originating from lakes in the Cordillera Blanca have occurred over the last century, several of which have had catastrophic impacts on cities and communities downstream. Glaciologists and engineers in Peru have been studying the lakes of the Cordillera Blanca for many years and have identified several lakes that are considered dangerous. However, a systematic analysis of all the lakes in the Cordillera Blanca has never before been attempted. Some methodologies for this type of systematic analysis have been proposed (eg. Emmer and Vilimek 2014; Wang, et al. 2011), but as yet they have only been applied to a few select lakes in the Cordillera Blanca. This study uses remotely sensed data to study all of the lakes of the Glacial Lake Inventory published by the Glaciology and Water Resources Unit of Peru's National Water Authority (UGRH 2011). The objective of this study is to assign a level of potential hazard to each glacial lake in the Cordillera Blanca and to ascertain if any of the lakes beyond those that have already been studied might pose a danger to nearby populations. A number of parameters of analysis, both quantitative and qualitative, have been selected to assess the hazard level of each glacial lake in the Cordillera Blanca using digital elevation models, satellite imagery, and glacier outlines. These parameters are then combined to come up with a preliminary assessment of the hazard level of each lake; the equation weighting each parameter draws on previously published methodologies but is tailored to the regional characteristics

  10. Pharmaceutical policy of the Andean sub-region.

    Science.gov (United States)

    1993-01-01

    Senior policy makers and health officials from the Andean countries--Bolivia, Colombia, Ecuador, Peru, and Venezuela--have developed a common pharmaceutical policy. The government's role is to assure availability and equal access to effective, quality, and affordable drugs and to safeguard their proper use. The government cannot delegate this role. The availability and accessibility of drugs gauge quality of health services and are social indicators of justice and equity. The public sector must use drugs from the essential drug list. These drugs are also valuable for the private sector. Drugs must not be treated like other merchandise, because the drug market is susceptible to misuse since the consumer cannot select the drug. Commercial advertising strongly influences prescribing of drugs and their use. The 2 major policy points are that promotion of essential drugs is the best approach from a health viewpoint and promotion of generic drug use is the best commercial alternative. The policy calls for the individual countries to pass a comprehensive drug law that reflects commitment to equity and appropriate use and incorporates standardization mechanisms. Criteria for selecting which drugs are allowed on the market include safety, proven efficacy, risk/benefit ratio, and treating the most common health problems at the lowest possible price. The Andean group is working towards harmonization of national essential drugs lists. To assure quality, health authorities must develop the capacity to enforce regulations when situations arise that threaten individual and community health. Supply, marketing, and logistics activities need to be improved and coordinated between the commercial and public sectors. Drug prices are being distanced from administrative control mechanisms and are going to be determined by a dynamic and well-supplied market. Drug information centers and prescription training are needed to achieve rational use of drugs. A joint pharmaceutical market for

  11. Integration, migration and sustainable development in the Andean group of nations.

    Science.gov (United States)

    Leon, R; Kratochwil, H

    1993-04-01

    This paper, which was presented at the 1993 meeting of the International Organization for Migration, summarizes past and recent progress in Andean integration and migration arrangements. Changes in the strategy of the Andean group of nations (GAN) have occurred in the adjustment to prevailing conditions at the subregional and international level. GAN includes Bolivia, Colombia, Ecuador, Peru, and Venezuela. The Andean Pact originated with the signing of the Cartegena Agreement in 1969. Members approved the Andean Strategic Design in 1989, which loosened up trade integration and the movement of capital, services, and persons across shared borders. The Strategic Design also addressed issues resulting from economic and social integration. A statement of migratory patterns among GAN, Andean integration during 1969-89, and the goals and operation of the Andean Strategic Design and integration are discussed in some detail. The Galapagos Declaration and the La Paz Statement of 1990 are also described. The present situation with Andean integration is based on the following meetings of Andean nations: the First Meeting of Migration Officials of the Andean Group of Nations in March 1991, the Second Meeting of Migration Officials in September 1991, and bilateral agreements between Andean nations. Seven basic conclusions are drawn: 1) the strategy is an institutional, deliberate, programmed process; 2) integration within GAN is the culmination of a joint, coordinated directive of achievement of sustainable development in the subregion which aims to reduce the economic gaps between the North and the South, to lessen the impact of protected markets of the North and their migration barriers, and to improve the possibility of development of technologically sophisticated human capital; 3) subregional policies are more sensitive to short-term change in domestic politics; 4) integration and migration can be sustained better with deliberate planning; 5) implementation is dependent on

  12. Sedimentary cyclicity in early Pleistocene, evaporitic, playa-lake lacustrine deposits in the Guadix-Baza basin (Betic Cordillera, Spain)

    International Nuclear Information System (INIS)

    The Guadix-Baza basin (Betic Cordillera, southern Spain) contains in its eastern sector an early Pleistocene (Gelasian and lowermost Calabrian) sedimentary unit that was deposited in a shallow lacustrine environment. Given that the chronological limits of this unit lie between 2.5 and 1.6 Ma BP, the thickness of its preserved sediments (400 m) and high sedimentation rate (44.4 cm/ka) are remarkable. Numerous sedimentary cycles marked by an alternation of marls and sands are commonly found in the marginal sectors and marls and gypsum in the central sector, which would owe their origins to permanent flooding and evaporation/ re-flooding phases due to global climatic changes. Spectral analyses carried out using Fourier transform have revealed the existence of temporary frequencies associated with sedimentary cycles of between 0.2 and 5.2 ka. The origin of these cycles may be associated with variations in solar radiation and oscillations in the Moons orbital position, which would induce global climatic changes resulting in the rise and fall of the water table of the lake. Autocorrelation analyses conducted separately on the marly and evaporitic levels support this conclusion, as they indicate the existence of significant direct correlations between about 4 to 12 sedimentary cycles, which would correspond to repetitions of the stratigraphic series over a time span of 1.3 to 4 ka. (Author)

  13. SENP1, but not fetal hemoglobin, differentiates Andean highlanders with chronic mountain sickness from healthy individuals among Andean highlanders.

    Science.gov (United States)

    Hsieh, Matthew M; Callacondo, David; Rojas-Camayo, Jose; Quesada-Olarte, Jose; Wang, Xunde; Uchida, Naoya; Maric, Irina; Remaley, Alan T; Leon-Velarde, Fabiola; Villafuerte, Francisco C; Tisdale, John F

    2016-06-01

    Chronic mountain sickness (CMS) results from chronic hypoxia. It is unclear why certain highlanders develop CMS. We hypothesized that modest increases in fetal hemoglobin (HbF) are associated with lower CMS severity. In this cross-sectional study, we found that HbF levels were normal (median = 0.4%) in all 153 adult Andean natives in Cerro de Pasco, Peru. Compared with healthy adults, the borderline elevated hemoglobin group frequently had symptoms (headaches, tinnitus, cyanosis, dilatation of veins) of CMS. Although the mean hemoglobin level differed between the healthy (17.1 g/dL) and CMS (22.3 g/dL) groups, mean plasma erythropoietin (EPO) levels were similar (healthy, 17.7 mIU/mL; CMS, 12.02 mIU/mL). Sanger sequencing determined that single-nucleotide polymorphisms in endothelial PAS domain 1 (EPAS1) and egl nine homolog 1 (EGLN1), associated with lower hemoglobin in Tibetans, were not identified in Andeans. Sanger sequencing of sentrin-specific protease 1 (SENP1) and acidic nuclear phosphoprotein 32 family, member D (ANP32D), in healthy and CMS individuals revealed that non-G/G genotypes were associated with higher CMS scores. No JAK2 V617F mutation was detected in CMS individuals. Thus, HbF and other classic erythropoietic parameters did not differ between healthy and CMS individuals. However, the non-G/G genotypes of SENP1 appeared to differentiate individuals with CMS from healthy Andean highlanders.

  14. A Comparative Analysis of Seismological and Gravimetric Crustal Thicknesses below the Andean Region with Flat Subduction of the Nazca Plate

    Directory of Open Access Journals (Sweden)

    Mario E. Gimenez

    2009-01-01

    Full Text Available A gravimetric study was carried out in a region of the Central Andean Range between 28∘ and 32∘ south latitudes and from 72∘ and 66∘ west longitudes. The seismological and gravimetrical Moho models were compared in a sector which coincides with the seismological stations of the CHARGE project. The comparison reveals discrepancies between the gravity Moho depths and those obtained from seismological investigations (CHARGE project, the latter giving deeper values than those resulting from the gravimetric inversion. These discrepancies are attenuated when the positive gravimetric effect of the Nazca plate is considered. Nonetheless, a small residuum of about 5 km remains beneath the Cuyania terrane region, to the east of the main Andean chain. This residuum could be gravimetrically justified if the existence of a high density or eclogitized portion of the lower crust is considered. This result differed from the interpretations from Project “CHARGE” which revealed that the entire inferior crust extending from the Precordillera to the occidental “Sierras Pampeanas” could be “eclogitized”. In this same sector, we calculated the effective elastic thickness (Te of the crust. These results indicated an anomalous value of Te = 30 km below the Cuyania terrane. This is further conclusive evidence of the fact that the Cuyania terrane is allochthonous, for which also geological evidences exist.

  15. Andesita Cerro Bola: Nueva unidad vinculada al magmatismo mioceno de la Cordillera de Olivares, San Juan, Argentina (30°35´S; 69°30´O Cerro Bola Andesite: New unit linked to the Miocene magmatism of the Olivares Cordillera, San Juan (30°35' S ; 68°30' W

    Directory of Open Access Journals (Sweden)

    A.F. Wetten

    2005-03-01

    Full Text Available El área de estudio se halla en la zona de Tocota, inmediatamente al este de la Cordillera de Olivares, en el borde oriental de la Cordillera Frontal, provincia de San Juan. En ella se encuentran unidades ígneas y sedimentarias del ciclo gondwánico, las que fueron intruidas y cubiertas en relación discordante por cuerpos subvolcánicos y volcánicos asignados anteriormente al ciclo ándico en sentido amplio, los cuales constituyen el principal objeto del presente estudio. Estos cuerpos han sido mapeados a fin de poder caracterizarlos adecuadamente, en el contexto estratigráfico de la región. Los afloramientos de interés han sido reconocidos en el cerro Bola y alrededores, donde se observan distribuidos irregularmente, cubriendo un área superior a 5 km². Las rocas, de coloración gris clara y composición andesítica - fenoandesítica, presentan estructuras de domo y colada. Estos afloramientos serían correlacionables con la unidad volcánica Pircas (Mioceno, la que aflora al oeste, y conformarían un evento magmático posterior al de pórfidos de diferente composición situados tanto en el arroyo Chita como en el cerro Divisadero. La extensión del área involucrada, la uniformidad litológica, el bajo grado de alteración y una edad radimétrica obtenida por el método K/Ar, fueron considerados para proponer a estas volcanitas como una unidad litoestratigráfica de edad miocena superior, con la denominación de Andesita Cerro Bola.The study area is located in the region of Tocota Creek, close to the Cordillera Olivares, eastern border of the Frontal Range, San Juan province. In this place, igneous and sedimentary units belonging to the Gondwanic cycle, were recognized. These units were intruded and unconformably covered by subvolcanic and volcanic bodies, which were commonly referred to the Tertiary or Andean cycle. The study of these bodies is the main proposal of this work. These bodies had been mapped in order to characterize them

  16. Resolving the tectonic transition between ancestral North America and the northern Cordillera

    Science.gov (United States)

    Schaeffer, A. J.; Audet, P.; Lebedev, S.

    2015-12-01

    The northern Cordillera, situated in the Canadian northwest, is one of the most actively deforming regions in Canada and host to the highest earthquake activity in the country. Furthermore, it presents a largely contiguous snapshot through almost 4 Gyr of Earth's history across a zone Mackenzie Mountains Experiment, new studies will leverage these datasets enabling more detailed imaging of the structure and seismicity across the region. Here we present a new high-resolution, vertically polarized shear speed and azimuthal model of northwestern Canada and Alaska, constrained by vertical component seismogram fits computed using the Automated Multimode Inversion of Surface, S, and multiple-S waveforms. With this new model, we aim to address key questions relating to the dynamics of the northern Cordillera, including how far west the craton edge extends at depth, in addition to the crustal thickness, velocity structure, and pattern of crustal fabrics around major faults throughout the region.

  17. Identificación, caracterización y dinámica de las geoformas glaciales y periglaciales en la Cordillera de los Andes a través de sensores remotos

    OpenAIRE

    Falaschi, Daniel

    2015-01-01

    El presente trabajo de Tesis Doctoral tuvo el objetivo de estudiar los glaciares y glaciares de escombros en tres regiones montañosas a lo largo de la Cordillera de los Andes Argentina: Monte San Lorenzo (Provincia de Santa Cruz), Volcán Domuyo (Provincia de Neuquén), y Nevados de Cachi (Provincia de Salta). Cada uno de estos sitios presenta características climáticas propias, representativas de tres porciones particulares de los Andes: Andes Patagónicos Meridionales, Andes Centrales Meridion...

  18. Climate change forces new ecological states in tropical Andean lakes.

    Directory of Open Access Journals (Sweden)

    Neal Michelutti

    Full Text Available Air temperatures in the tropical Andes have risen at an accelerated rate relative to the global average over recent decades. However, the effects of climate change on Andean lakes, which are vital to sustaining regional biodiversity and serve as an important water resource to local populations, remain largely unknown. Here, we show that recent climate changes have forced alpine lakes of the equatorial Andes towards new ecological and physical states, in close synchrony to the rapid shrinkage of glaciers regionally. Using dated sediment cores from three lakes in the southern Sierra of Ecuador, we record abrupt increases in the planktonic thalassiosiroid diatom Discostella stelligera from trace abundances to dominance within the phytoplankton. This unprecedented shift occurs against the backdrop of rising temperatures, changing atmospheric pressure fields, and declining wind speeds. Ecological restructuring in these lakes is linked to warming and/or enhanced water column stratification. In contrast to seasonally ice-covered Arctic and temperate alpine counterparts, aquatic production has not increased universally with warming, and has even declined in some lakes, possibly because enhanced thermal stability impedes the re-circulation of hypolimnetic nutrients to surface waters. Our results demonstrate that these lakes have already passed important ecological thresholds, with potentially far-reaching consequences for Andean water resources.

  19. Andean microrefugia: testing the Holocene to predict the Anthropocene.

    Science.gov (United States)

    Valencia, Bryan G; Matthews-Bird, Frazer; Urrego, Dunia H; Williams, Joseph J; Gosling, William D; Bush, Mark

    2016-10-01

    Microrefugia are important for supporting populations during periods of unfavourable climate change and in facilitating rapid migration as conditions ameliorate. With ongoing anthropogenic climate change, microrefugia could have an important conservation value; however, a simple tool has not been developed and tested to predict which settings are microrefugial. We provide a tool based on terrain ruggedness modelling of individual catchments to predict Andean microrefugia. We tested the predictions using nine Holocene Polylepis pollen records. We used the mid-Holocene dry event, a period of peak aridity for the last 100 000 yr, as an analogue climate scenario for the near future. The results suggest that sites with high terrain rugosity have the greatest chance of sustaining mesic conditions under drier-than-modern climates. Fire is a feature of all catchments; however, an increase in fire is only recorded in settings with low rugosity. Owing to rising temperatures and greater precipitation variability, Andean ecosystems are threatened by increasing moisture stress. Our results suggest that high terrain rugosity helps to create more resilient catchments by trapping moisture through orographic rainfall and providing firebreaks that shelter forest from fire. On this basis, conservation policy should target protection and management of catchments with high terrain rugosity. PMID:27374975

  20. Andean rural children's views of the environment: A qualitative study

    Science.gov (United States)

    Maurial, Mahia

    Andean rural children's drawings and narratives about their crops and the immediate biological environment are rich tools to understand local views of the environment. Children's drawings and narratives were collected and linked to interviews as well as participant observation gathered from parents, leaders and teachers. The research sites are the community of Willca and the school of Mayu. Fieldwork was completed in 1998. In the conceptual framework I distinguish between two dissimilar knowledges, school knowledge and local knowledge. These knowledges produce two dissimilar views of the environment. I further analyze relationships of knowledge and power and argue that school knowledge overpowers local knowledge. Concomitantly, I studied set of ideas associated with two knowledges aforementioned: superacion (surpass) and regeneration (Apffel-Marglin 1995). Although these ideas coexist in peoples' minds they are not linked or effectively connected. In order to link local knowledge and school knowledge together, I propose the integration of environmental studies and art education to enhance a local sense of place (Blandy et. al 1993) in Andean and other schools. This will contribute to grassroots educational policy.

  1. Lichenometry in the Cordillera Blanca, Peru : "Little Ice Age" moraine chronology

    OpenAIRE

    O. Solomina; Jomelli, Vincent; Kaser, G.; Ames, A; Berger, B; Pouyaud, Bernard (dir.)

    2007-01-01

    This paper is a comparison and compilation of lichenometric and geomorphic studies performed by two independent teams in the Cordillera Blanca, Peru, in 1996 and 2002 on 66 "Little Ice Age" moraines of 14 glaciers. Using eleven new control points, we recalibrated the initial rapid growth phase of the previously established Rhizocarpon subgenus Rhizocarpon growth curve. This curve was then used to estimate the age of "Little Ice Age" moraines. The time of deposition of the most prominent and n...

  2. Reducing risks from hazardous glacier lakes in the Cordillera Blanca (Peru): Six decades of experience and perspectives for the future

    Science.gov (United States)

    Portocarrero, Cesar; Cochachin, Alejo; Frey, Holger; González, Cesar; Haeberli, Wilfried; Huggel, Christian

    2016-04-01

    Outbursts from glacier lakes at various spatial and temporal scales have had marked geomorphological effects in many mountain ranges. In many glacierized Andean mountain regions substrates of human settlements made out of flood and debris-flow deposits are testimonies of such events. Examples in the Cordillera Blanca, Peru, are the towns of Caraz, Carhuaz or parts of Huaraz. Continued glacier shrinking since the end of the Little Ice Age caused the formation or enlargement of numerous lakes. The outburst of Laguna Palcacocha, destroying the centre of Huaraz and causing more than 1800 losses of life in December 1941, marked the beginning of systematic risk reduction work in Peru. Corresponding efforts included glacier and lake inventories, hazard assessments, definition of high-risk situations, and completion of engineering work for lake-level lowering in more than 30 cases. The latter comprises outlet reinforcements on morainic dams as well as artificial tunnels in bedrock thresholds. This work has been remarkably efficient as documented in the latest case of the Laguna Huallcacocha (Carhuaz-Ancash), where the earlier made installations withstood the erosive power of an impact wave from an ice avalanche in 2015. In the case of the Laguna 513, the impact wave and far-reaching flood caused by a rock/ice avalanche from Nevado Hualcán in April 2010 showed that the risk had been essentially reduced by the preventive lake-level lowering in the early 1990s but not to zero. Risk assessments, planning, construction and non-structural risk reduction efforts continue. Work is in progress to increase the safety of Laguna Palcacocha where extensive assessments and model calculations had been carried out. Risks related to rock/ice avalanches into lakes from steep icy slopes and related to de-buttressing processes as well as long-term permafrost degradation increases. Based on morphological indications and numerical modelling (GlabTop) an inventory of possible future lakes

  3. Extreme high prevalence of a defective mannose-binding lectin (MBL2 genotype in native South American West Andean populations.

    Directory of Open Access Journals (Sweden)

    José Raul Sandoval

    Full Text Available Mannose-binding lectin (MBL is one of the five recognition molecules in the lectin complement pathway. Common variant alleles in the promoter and structural regions of the human MBL gene (MBL2 influence the stability and serum concentration of the protein. Epidemiological studies have shown that MBL2 variant alleles are associated with susceptibility to and the course of different types of infectious and inflammatory conditions. However, it has been suggested that these alleles are maintained in different populations due to selected advantages for carriers. We investigated the MBL2 allelic variation in indigenous individuals from 12 different West Central South America localities spanning from the desert coast, high altitude Andean plates and the Amazon tropical forest within the territories of Peru (n = 249 (Departments of Loreto, Ucayali, Lambayeque, Junin, Ayacucho, Huancayo and Puno, and Ecuador (n = 182 (Region of Esmeraldas and Santo Domingo de los Colorados. The distribution of MBL2 genotypes among the populations showed that the defective variant LYPB haplotype was very common. It showed the highest frequencies in Puno (Taquile (0.80, Amantani (0.80 and Anapia (0.58 islander communities of the Lake Titicaca, but lower frequencies of 0.22 in Junin (Central Andean highland and Ucayali (Central Amazonian forest, as well as 0.27 and 0.24 in the Congoma and Cayapa/Chachis populations in the Amazonian forest in Ecuador were also observed. Our results suggest that the high prevalence of the MBL2 LYPB variant causing low levels of functional MBL in serum may mainly reflect a random distribution due to a population bottleneck in the founder populations.

  4. Giant evaporite belts of the Neogene central Andes

    Science.gov (United States)

    Alonso, Ricardo N.; Jordan, Teresa E.; Tabbutt, Kenneth T.; Vandervoort, Dirk S.

    1991-04-01

    Large volumes of continental evaporites accumulated within the central Andes during Neogene uplift of the Altiplano-Puna plateau and development of the Andean volcanic arc. Halite and gypsum are dominant minerals, along with local and economically important borates. Playa conditions have existed since ca. 15 Ma; halite and borate deposition has occurred for the past 7 to 8 m.y. Evaporites formed in salar environments (e.g., playa lakes) and are characterized by complex mineral assemblages, occurrence, zonation, and geochemistry. Evaporite deposition was controlled by volcanism, geothermal activity, closed drainage, and climate. These Andean deposits, and their controls, differ from evaporites in other continental and marine environments.

  5. Large-scale patterns of turnover and Basal area change in Andean forests.

    Directory of Open Access Journals (Sweden)

    Selene Báez

    Full Text Available General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century.

  6. Revisiting the Andean butterfly Eryphanis zolvizora group (Lepidoptera, Nymphalidae: one or several species?

    Directory of Open Access Journals (Sweden)

    Patrick Blandin

    2014-01-01

    Full Text Available Eryphanis zolvizora (Hewitson, 1877 is a rare Andean endemic butterfly, described from Bolivia, which has been historically classified either as a unique species, or as part of a group of three allopatric species from Bolivia, Ecuador and Colombia. In this paper, the group is revised using more than 200 specimens housed in 34 European, and North and South American public and private collections. For the first time, the presence of the group in Western Ecuador and Venezuela is confirmed, and important data on Peruvian populations are provided. In some populations, individual variations of genitalia are observed. Nevertheless, male genitalia allow the distinction of four geographical groups. Considering also habitus characters, eight taxa are distinguished and considered to be subspecies, of which five are new: Eryphanis zolvizora inca ssp. nov., Eryphanis zolvizora chachapoya ssp. nov., Eryphanis zolvizora casagrande ssp. nov.., Eryphanis zolvizora reyi ssp. nov., and Eryphanis zolvizora isabelae ssp. nov.  In the present state of knowledge, these taxa are allopatric, except for a possible geographic overlap in central Peru, where data are insufficient to prove sympatry. The “several subspecies vs. several species” dilemma is discussed, considering its impact for conservation action and policies.

  7. Effects of the hydrological cycle on the phycoperiphyton assemblage in an Andean foothill stream in Colombia

    Directory of Open Access Journals (Sweden)

    María I. Ríos-Pulgarín

    2016-03-01

    Full Text Available The Guarinó River is a torrential system that is located in the foothills of the Colombian central Andean mountains that naturally experiences severe hydrological disturbances, which were higher during the Niño-Niña/Southern Oscillation (ENSO between 2007 and 2010. The seasonal and interannual variabilities in the taxonomic composition, richness and density of phycoperiphyton assemblages (ecological descriptors from the Guarinó River were examined in relation to the physical and chemical environmental changes associated with the hydrological cycle between 2007 and 2010. The values of the ecological descriptors and environmental variables were analysed via ANOVA, ANCOVA and Canonical Discriminant Analysis to establish temporal patterns and relationships between the variables. Eighty-seven taxa belonging to Cyanobacteria, Chlorophyta, Charophyta, Ochrophyta, Cryptophyta, Euglenozoa and Dinophyta were identified. Flow, water temperature and dissolved oxygen corresponded with the hydroclimatic variation and allowed for the differentiation of the El Niño and La Niña periods. Phycoperiphyton density differences matched the environmental variation pattern with a significant annual increase in the number of individuals during El Niño, whereas annual differences related to richness were not evident. The replacement of genera according to their drag or desiccation tolerance and the persistence of genera tolerant to high hydrological disturbances, such as Fragilaria, Nitzschia, Gomphonema, Navicula and especially Lyngbya, was observed.

  8. Large-Scale Patterns of Turnover and Basal Area Change in Andean Forests

    Science.gov (United States)

    Blundo, Cecilia; Aguilar, Manuel; Aguirre, Nikolay; Aquirre, Zhofre; Álvarez, Esteban; Cuesta, Francisco; Farfán-Ríos, William; García-Cabrera, Karina; Grau, Ricardo; Linares-Palomino, Reynaldo; Malizia, Lucio R.; Cruz, Omar Melo; Osinaga, Oriana; Reynel, Carlos; Silman, Miles R.

    2015-01-01

    General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment) and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century. PMID:25973977

  9. An Outbreak of Bartonella bacilliformis in an Endemic Andean Community

    Science.gov (United States)

    Sanchez Clemente, Nuria; Ugarte-Gil, Cesar; Solorzano, Nelson; Maguiña, Ciro; Moore, David

    2016-01-01

    Background Bartonellosis affects small Andean communities in Peru, Colombia and Ecuador. Research in this area has been limited. Methods Retrospective review of 191 cases of bartonellosis managed in Caraz District Hospital, Peru, during the last outbreak (2003). Results The majority of cases (65%) were 14 years old and younger. There was a peak in acute cases after the rainy season; chronic cases presented more constantly throughout the year. The sensitivity of blood smear against blood culture in acute disease was 25%. The most commonly used treatment for chronic disease was rifampicin; chloramphenicol was used to treat most acute cases. Complications arose in 6.8% and there were no deaths. Conclusions Diagnostic and treatment algorithms for acute and chronic bartonellosis have been developed without a strong evidence base. Preparation of ready-to-go operational research protocols for future outbreaks would strengthen the evidence base for diagnostic and treatment strategies and enhance opportunities for control. PMID:26991495

  10. Spatial random downscaling of rainfall signals in Andean heterogeneous terrain

    Science.gov (United States)

    Posadas, A.; Duffaut Espinosa, L. A.; Yarlequé, C.; Carbajal, M.; Heidinger, H.; Carvalho, L.; Jones, C.; Quiroz, R.

    2015-07-01

    Remotely sensed data are often used as proxies for indirect precipitation measures over data-scarce and complex-terrain areas such as the Peruvian Andes. Although this information might be appropriate for some research requirements, the extent at which local sites could be related to such information is very limited because of the resolution of the available satellite data. Downscaling techniques are used to bridge the gap between what climate modelers (global and regional) are able to provide and what decision-makers require (local). Precipitation downscaling improves the poor local representation of satellite data and helps end-users acquire more accurate estimates of water availability. Thus, a multifractal downscaling technique complemented by a heterogeneity filter was applied to TRMM (Tropical Rainfall Measuring Mission) 3B42 gridded data (spatial resolution ~ 28 km) from the Peruvian Andean high plateau or Altiplano to generate downscaled rainfall fields that are relevant at an agricultural scale (spatial resolution ~ 1 km).

  11. A new Andean species of Philodryas (Dipsadidae, Xenodontinae) from Ecuador.

    Science.gov (United States)

    Zaher, Hussam; Arredondo, Juan C; Valencia, Jorge H; Arbeláez, Ernesto; Rodrigues, Miguel T; Altamirano-Benavides, Marco

    2014-01-01

    We describe a new species of Philodryas from the highlands of southern Ecuador. The new species is distinguished from all known species of Philodryas by a unique combination of coloration, scalation, and hemipenial characters. The new species resembles Philodryas simonsii in color pattern. However, they differ notoriously by their hemipenial morphology. The three other trans-Andean members of the genus (Philodryas simonsii, Philodryas chamissonis, and Philodryas tachymenoides), along with the new species, compose a probably monophyletic group that may be characterized by the presence of ungrooved postdiastemal teeth in the maxilla. Unlike most species of the genus Philodryas, the new species shows a restricted distribution, being apparently endemic to a small region of high-altitude (3150-4450m) grasslands in the southern Andes of Ecuador. PMID:24872238

  12. Climatic and lacustrine morphometric controls of diatom paleoproductivity in a tropical Andean lake

    Science.gov (United States)

    Bao, R.; Hernández, A.; Sáez, A.; Giralt, S.; Prego, R.; Pueyo, J. J.; Moreno, A.; Valero-Garcés, B. L.

    2015-12-01

    The coupling of lake dynamics with catchment biogeochemistry is considered the key element controlling primary production in mountain lakes at time scales of a few decades to millennia, yet little is known on the impacts of the morphometry of lakes throughout their ontogeny. As Lake Chungará (Central Andean Altiplano, northern Chile) experienced long-term lake-level fluctuations that strongly modified its area:volume ratio, it is an ideal system for exploring the relative roles that long-term climatic shifts and lake morphometry play on biosiliceous lacustrine productivity. In this paper, we review previous data on the percent contents of total organic carbon, total inorganic carbon, total nitrogen, total biogenic silica, isotopic composition of organic matter, carbonates, and diatom frustules, as well as data on the abundance of the chlorophycean Botryococcus braunii in this lake for the period 12,400-1300 cal yr BP. We also include new data on organic carbon and biogenic silica mass accumulation rates and the diatom assemblage composition of an offshore core dated using 14C and U/Th. Biosiliceous productivity in Lake Chungará was influenced by shifts in allochthonous nutrient inputs related to variability in precipitation. Humid phases dated at approx. 12,400 to 10,000 and 9600 to 7400 cal yr BP coincide with periods of elevated productivity, whereas decreases in productivity were recorded during arid phases dated at approx. 10,000 to 9600 and 7400 to 3550 cal yr BP (Andean mid-Holocene Aridity Period). However, morphometry-related in-lake controls led to a lack of a linear response of productivity to precipitation variability. During the late Glacial to early Holocene, lowstands facilitated complete water column mixing, prompting episodic massive blooms of a large centric diatom, Cyclostephanos cf. andinus. Thus, moderate productivity could be maintained, regardless of aridity, by this phenomenon of morphometric eutrophy during the early history of the lake

  13. Genetic diversity of Phytophthora infestans in the Northern Andean region

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    Grünwald Niklaus J

    2011-02-01

    Full Text Available Abstract Background Phytophthora infestans (Mont. de Bary, the causal agent of potato late blight, is responsible for tremendous crop losses worldwide. Countries in the northern part of the Andes dedicate a large proportion of the highlands to the production of potato, and more recently, solanaceous fruits such as cape gooseberry (Physalis peruviana and tree tomato (Solanum betaceum, all of which are hosts of this oomycete. In the Andean region, P. infestans populations have been well characterized in Ecuador and Peru, but are poorly understood in Colombia and Venezuela. To understand the P. infestans population structure in the Northern part of the Andes, four nuclear regions (ITS, Ras, β-tubulin and Avr3a and one mitochondrial (Cox1 region were analyzed in isolates of P. infestans sampled from different hosts in Colombia and Venezuela. Results Low genetic diversity was found within this sample of P. infestans isolates from crops within several regions of Colombia and Venezuela, revealing the presence of clonal populations of the pathogen in this region. We detected low frequency heterozygotes, and their distribution patterns might be a consequence of a high migration rate among populations with poor effective gene flow. Consistent genetic differentiation exists among isolates from different regions. Conclusions The results here suggest that in the Northern Andean region P. infestans is a clonal population with some within-clone variation. P. infestans populations in Venezuela reflect historic isolation that is being reinforced by a recent self-sufficiency of potato seeds. In summary, the P. infestans population is mainly shaped by migration and probably by the appearance of variants of key effectors such as Avr3a.

  14. Farmers' participation and breeding for durable disease resistance in the Andean region

    NARCIS (Netherlands)

    Danial, D.L.; Parlevliet, J.E.; Almekinders, C.J.M.; Thiele, G.

    2007-01-01

    In the Andean region, the Preduza project and its partners combined breeding for durable disease resistance using locally adapted cultivars and farmer participatory methods. The approach taken resembles participatory variety selection (PVS). Farmers participated in the selection of advanced material

  15. Watershed-based natural research management: Lessons from projects in the Andean region

    OpenAIRE

    Sowell, A.R.

    2009-01-01

    This Undergraduate Honors Thesis focuses on how different factors affect the success of a watershed management project and lessons learned from projects in the Andean Region. LTRA-3 (Watershed-based NRM for Small-scale Agriculture)

  16. Genetic diversity and germplasm conservation of three minor Andean tuber crop species

    OpenAIRE

    Malice M.; Baudoin JP.

    2009-01-01

    In traditional Andean agrosystems, three minor tuber crop species are of regional or local importance: oca (Oxalis tuberosa Molina), ulluco (Ullucus tuberosus Caldas) and mashua (Tropaeolum tuberosum Ruiz and Pav.). Genetic diversity within these species is very large and could result from the high ecological and cultural variability that characterizes the Andean area. Nowadays, many anthropic or ecological factors cause the loss of diversity and contribute to genetic erosion. The development...

  17. A tectonically controlled basin-fill within the Valle del Cauca, West-Central Colombia

    Energy Technology Data Exchange (ETDEWEB)

    Rine, J.M.; Keith, J.F. Jr.; Alfonso, C.A.; Ballesteros, I.; Laverde, F.; Sacks, P.E.; Secor, D.T. Jr. (Univ. of South Carolina, Columbia (United States)); Perez, V.E.; Bernal, I.; Cordoba, F.; Numpaque, L.E. (Ecopetrol, Bogota (Colombia))

    1993-02-01

    Tertiary strata of the Valle del Cauca reflect a forearc/foreland basin tectonic history spanning a period from pre-uplift of the Cordillera Central to initiation of uplift of the Cordillera Occidental. Stratigraphy of the Valle del Cauca begins with Jurassic-Cretaceous rocks of exotic and/or volcanic provenance and of oceanic origin. Unconformably overlying these are Eocene to Oligocene basal quartz-rich sandstones, shallow marine algal limestones, and fine-grained fluvial/deltaic mudstones and sandstones with coalbeds. These Eocene to Oligocene deposits represent a period of low tectonic activity. During late Oligocene to early Miocene, increased tectonic activity produced conglomeratic sediments which were transported from east to west, apparently derived from uplift of the Cordillera Central, and deposited within a fluvial to deltaic setting. East-west shortening of the Valle del Cauca basin folded the Eocene to early Miocene units, and additional uplift of the Cordillera Central during the later Miocene resulted in syn-tectonic deposition of alluvial fans. After additional fold and thrust deformation of the total Eocene-Miocene basin-fill, tectonic activity abated and Pliocene-Quaternary alluvial and lacustrine strata were deposited. Within the framework of this depositional and tectonic history of the Valle del Cauca, hydrocarbon exploration strategies can be formulated and evaluated.

  18. Los deslizamientos de la cordillera neuquina al sur delos 38° S: suinducción

    OpenAIRE

    Emilio F González Díaz; Andrés Folguera

    2009-01-01

    Las conclusiones sobre losdeslizamientos individualizados en la cordillera neuquina (36°-38°S), (suinducción sísmica; rechazo de la consideración de sus depósitos como till),indujo a proyectar su estudio al sur de los 38°S. Se distinguieron inéditaszonas de deslizamientos, cuya promoción y contexto sismotectónico difieren delos reconocidos entre los 36°-38°S. Su estudio regional, que abarcó trescomarcas (Aluminé, Chapelco y Arroyo Limay Chico), comprobó el predominio delas corrientes de tierr...

  19. Dynamic paleogeography of the Jurassic Andean Basin: pattern of transgression and localisation of main straits through the magmatic arc

    Directory of Open Access Journals (Sweden)

    J-C. Vicente

    2005-03-01

    Full Text Available The paleogeographic evolution of the Jurassic Andean retroarc basin is examined at a global scale for the Central Andes. In this paper, it is called for the striking continuity and lasting of the active volcanic arc. Both direct and indirect sedimentologic evidences allow to locate the western border (insular of the basin and opposite it with the eastern border (cratonic. Emphasis is placed on the volcaniclastic deposits and synsedimentary structures associated with this insular border. It is concluded that the arc magmatic activity has contributed considerably in sediment supply to the basin. Extent and continuity of the arc implies to locate the straits connecting with the Paleopacific. Systematic check of the time of transgressions coupled with sequential facies analysis provides a dynamic outlook of the transgressive process. Sectors with early transgression allow to distinguish two main gulfs of passage through the arc from which waters have progressed lengthwise at the same time northward and southward in a narrow retroarc furrow : the first at latitude of Taltal (25°S, the second at latitude of Curepto (35°S. Both initiated in the upper Triassic and extended during the Hettangian. The evolution as separate basins (Tarapacá and Aconcagua-Neuquén ended by fusion in middle Pliensbachian giving rise to a continuous elongated basin from Chubut to northern Peru. The remarkable continuity and narrowness of the Andean Basin leaves no doubt about its tectonic control. This stems to its geotectonic setting as a typical retroarc basin adjacent to a very active magmatic arc and explains the extreme mobility of its insular margin characterized by a huge volcanoclastic apron with associated debris flows and turbidites.

  20. Hydrodynamic Modeling of Flash Floods in an Andean Stream: Challenges for Assessing Flood Hazards in Mountain Rivers

    Science.gov (United States)

    Contreras, M. T.; Escauriaza, C. R.

    2015-12-01

    Rain-induced flash floods are common events in regions close to the southern Andes, in north and central Chile. Rapid urban development combined to the changing climate and ENSO effects have resulted in an alarming proximity of flood-prone streams to densely populated areas in the Andean foothills, increasing the risk for cities and infrastructure. Simulations of rapid floods in these complex watersheds are particularly challenging, especially if there is insufficient geomorphological and hydrometeorological data. In the Quebrada de Ramón, an Andean stream that passes through a highly populated area in the east part of Santiago, Chile, previous events have demonstrated that sediment concentration, flow resistance, and the characteristic temporal and spatial scales of the hydrograph, are important variables to predict the arrival time of the peak discharge, flow velocities and the extension of inundated areas. The objective of this investigation is to improve our understanding of the dynamics of flash floods in the Quebrada de Ramón, quantifying the effects of these factors on the flood propagation. We implement a two-dimensional model based on the shallow water equations (Guerra et al. 2014) modified to account for hyperconcentrated flows over natural topography. We evaluate events of specific return periods and sediment concentrations, using different methodologies to quantify the flow resistance in the channel and floodplains. Through this work we provide a framework for future studies aimed at improving hazard assessment, urban planning, and early warning systems in urban areas near mountain streams with limited data, and affected by rapid flood events. Work supported by Fondecyt grant 1130940 and CONICYT/FONDAP grant 15110017.

  1. Subduction system and flat slab beneath the Eastern Cordillera of Colombia

    Science.gov (United States)

    Chiarabba, Claudio; De Gori, Pasquale; Faccenna, Claudio; Speranza, Fabio; Seccia, Danilo; Dionicio, Viviana; Prieto, Germán. A.

    2016-01-01

    Seismicity at the northern terminus of the Nazca subduction is diffused over a wide area containing the puzzling seismic feature known as the Bucaramanga nest. We relocate about 5000 earthquakes recorded by the Colombian national seismic network and produce the first 3-D velocity model of the area to define the geometry of the lithosphere subducting below the Colombian Andes. We found lateral velocity heterogeneities and an abrupt offset of the Wadati-Benioff zone at 5°N indicating that the Nazca plate is segmented by an E-W slab tear, that separates a steeper Nazca segment to the south from a flat subduction to the north. The flat Nazca slab extends eastward for about 400 km, before dip increases to ˜50° beneath the Eastern Cordillera, where it yields the Bucaramanga nest. We explain this puzzling locus of intermediate-depth seismicity located beneath the Eastern Cordillera of Colombia as due to a massive dehydration and eclogitization of a thickened oceanic crust. We relate the flat subducting geometry to the entrance at the trench at ca. 10 Ma of a thick - buoyant oceanic crust, likely a volcanic ridge, producing a high coupling with the overriding plate. Sub-horizontal plate subduction is consistent with the abrupt disappearance of volcanism in the Andes of South America at latitudes > 5°N.

  2. Isotopic evolution of the idaho batholith and Challis intrusive province, Northern US Cordillera

    Science.gov (United States)

    Gaschnig, R.M.; Vervoort, J.D.; Lewis, R.S.; Tikoff, B.

    2011-01-01

    The Idaho batholith and spatially overlapping Challis intrusive province in the North American Cordillera have a history of magmatism spanning some 55 Myr. New isotopic data from the ???98 Ma to 54 Ma Idaho batholith and ???51 Ma to 43 Ma Challis intrusions, coupled with recent geochronological work, provide insights into the evolution of magmatism in the Idaho segment of the Cordillera. Nd and Hf isotopes show clear shifts towards more evolved compositions through the batholith's history and Pb isotopes define distinct fields correlative with the different age and compositionally defined suites of the batholith, whereas the Sr isotopic compositions of the various suites largely overlap. The subsequent Challis magmatism shows the full range of isotopic compositions seen in the batholith. These data suggest that the early suites of metaluminous magmatism (98-87 Ma) represent crust-mantle hybrids. Subsequent voluminous Atlanta peraluminous suite magmatism (83-67 Ma) results primarily from melting of different crustal components. This can be attributed to crustal thickening, resulting from either subduction processes or an outboard terrane collision. A later, smaller crustal melting episode, in the northern Idaho batholith, resulted in the Bitterroot peraluminous suite (66-54 Ma) and tapped different crustal sources. Subsequent Challis magmatism was derived from both crust and mantle sources and corresponds to extensional collapse of the over-thickened crust. ?? The Author 2011. Published by Oxford University Press. All rights reserved.

  3. Storage of carbon in natural grasses high andean

    Directory of Open Access Journals (Sweden)

    Raúl Marino Yaranga Cano

    2013-12-01

    Full Text Available The aim of the study was to determine the capacity of storage of carbon in species of grasses natural of high andean, between January of 2012 and March of 2013. They were defined two sampling areas in the districts of Huasicancha and Chicche of the county of Huancayo, Junín. The first of the areas was located in the place Pumahuasi (18L 466456E 8628580N and the second in Vista Alegre (18L 464886E 8642964N, between 3 845 and 3 870 meters of altitude. 10 plants per species were collected at random, between April and May, considering the moment of maximum growth of the plants. The samples were washed and dried off to the atmosphere during 15 days, being completed the drying in a stove to 60 °C, during 48 hours. The determination of the percentage of dry matter of the samples was carried out by the difference between the initial and final weights. While that the determination of the percentage of carbon was carried out through the method of Walkley-Black. The results of the correlation of weight between air biomass and biomass radicular were highly significant r = 0.9856 ** and b = 3.4507. The percentage of the weight of the root regarding that of the air biomass oscillated between 27.93% and 30.20%, respectively. The content of carbon expressed as percentage varied according to the part of the plant and the origin place.

  4. The epidemiology and control of leishmaniasis in Andean countries

    Directory of Open Access Journals (Sweden)

    Davies Clive Richard

    2000-01-01

    Full Text Available This paper reviews the current knowledge of leishmaniasis epidemiology in Venezuela, Colombia, Ecuador, Peru, and Bolivia. In all 5 countries leishmaniasis is endemic in both the Andean highlands and the Amazon basin. The sandfly vectors belong to subgenera Helcocyrtomyia, Nyssomiya, Lutzomyia, and Psychodopygus, and the Verrucarum group. Most human infections are caused by Leishmania in the Viannia subgenus. Human Leishmania infections cause cutaneous lesions, with a minority of L. (Viannia infections leading to mucocutaneous leishmaniasis. Visceral leishmaniasis and diffuse cutaneous leishmaniasis are both rare. In each country a significant proportion of Leishmania transmission is in or around houses, often close to coffee or cacao plantations. Reservoir hosts for domestic transmission cycles are uncertain. The paper first addresses the burden of disease caused by leishmaniasis, focusing on both incidence rates and on the variability in symptoms. Such information should provide a rational basis for prioritizing control resources, and for selecting therapy regimes. Secondly, we describe the variation in transmission ecology, outlining those variables which might affect the prevention strategies. Finally, we look at the current control strategies and review the recent studies on control.

  5. The epidemiology and control of leishmaniasis in Andean countries

    Directory of Open Access Journals (Sweden)

    Clive Richard Davies

    2000-12-01

    Full Text Available This paper reviews the current knowledge of leishmaniasis epidemiology in Venezuela, Colombia, Ecuador, Peru, and Bolivia. In all 5 countries leishmaniasis is endemic in both the Andean highlands and the Amazon basin. The sandfly vectors belong to subgenera Helcocyrtomyia, Nyssomiya, Lutzomyia, and Psychodopygus, and the Verrucarum group. Most human infections are caused by Leishmania in the Viannia subgenus. Human Leishmania infections cause cutaneous lesions, with a minority of L. (Viannia infections leading to mucocutaneous leishmaniasis. Visceral leishmaniasis and diffuse cutaneous leishmaniasis are both rare. In each country a significant proportion of Leishmania transmission is in or around houses, often close to coffee or cacao plantations. Reservoir hosts for domestic transmission cycles are uncertain. The paper first addresses the burden of disease caused by leishmaniasis, focusing on both incidence rates and on the variability in symptoms. Such information should provide a rational basis for prioritizing control resources, and for selecting therapy regimes. Secondly, we describe the variation in transmission ecology, outlining those variables which might affect the prevention strategies. Finally, we look at the current control strategies and review the recent studies on control.

  6. Mechanisms of O2 transport in Andean dogs.

    Science.gov (United States)

    Banchero, N; Cruz, J; Bustinza, J

    1975-04-01

    Using previously inserted catheters, 11 dogs native to high altitude (7.5-23 kg bwt) were studied standing and unsedated in Cerro de Pasco, Peru at 4350 meters. Hemoglobin (Hb), hematocrit (Hct), O2 and CO2 contents, PO2, PCO2 and pH were measured in simultaneously obtained arterial and mixed venous blood samples. Blood pressures were measured in the pulmonary artery and the left ventricle and cardiac output (Q) was determined by dye dilution. Moderately higher values for Hb and Hct were found in these dogs. Hb-O2 affinity was no different than that found in sea level dogs: the P50 in the Andean dogs was 31.6 mm Hg at 38 degrees C and pH of 7.4. Because of the low barometric pressure at 4350 m (458 mmHg) the partial pressures of oxygen in inspired and in alveolar air were lower than at sea level: 84.3 and 56.4 mm Hg, respectively. PAO2 and PVO2, were 55.5 and 32.9 mm Hg while the SAO2 and SVO2 were 79.5 and 50.7%, respectively. Marked hyperventilation was observed (PACO2, 25.6 mm Hg) however, pH was normal. Cardiac output was normal (average 162 plus or minus 39 ml/min/kg). Moderate pulmonary arterial hypertension was observed in the presence of normal left ventricular end diastolic pressure suggesting increased pulmonary vascular resistance.

  7. Cerebral vasoreactivity in Andeans and headache at sea level.

    Science.gov (United States)

    Appenzeller, O; Passino, C; Roach, R; Gamboa, J; Gamboa, A; Bernardi, L; Bonfichi, M; Malcovati, L

    2004-04-15

    Headache is common in Cerro de Pasco (CP), Peru (altitude 4338 m) and was present in all patients with chronic mountain sickness (CMS) in CP reported here. Forty-seven percent of inhabitants report headache. Twenty-four percent of men have migraine with aura, with an average of 65 attacks a year. We assessed vasoreactivity of the cerebral vessels to CO2 by rebreathing and to NO by the administration of isosorbite dinitrate (IDN), a nitric oxide (NO) donor, using transcranial Doppler ultrasound in the middle cerebral artery (MCA) in natives of CP, some of whom suffered from CMS. We repeated the measurements in Lima (altitude 150 m) in the same subjects within 24 h of arrival. Vasodilatation in the middle cerebral artery supply territory in response to CO2 and NO, both physiologic vasodilators, is defective in Andean natives at altitude and in the same subjects at sea level. Incapacitating migraine can occur with impaired cerebral vasoreactivity to physiologic vasodilators. We propose that susceptibility to migraine might depend in part on gene expression with consequent alterations of endothelial function.

  8. Stable isotope evidence for multiple pulses of rapid surface uplift in the Central Andes, Bolivia

    OpenAIRE

    Leier, Andrew; McQuarrie, Nadine; Garzione, Carmala; Eiler, John

    2013-01-01

    Paleoelevation histories from mountain belts like the Central Andes of Bolivia provide important constraints on the timing and geodynamic mechanisms associated with surface uplift. We present new oxygen and carbon isotope data (δ^(18)O, δ^(13)C, and Δ_(47)) from Oligocene–Miocene strata exposed in the Eastern Cordillera of the Bolivian Central Andes in order to reconstruct both the deformation and paleoelevation history of the region prior to late Miocene time. Paleosol carbonate in strata >2...

  9. Regeneración Natural del Roble Negro (Colombobalanus excelsa, Fagaceae en Dos Poblaciones de la Cordillera Oriental de los Andes, Colombia Natural Regeneration of Black Oak (Colombobalanus excelsa, Fagaceae in Two Populations from the Cordillera Oriental of the Colombian Andes

    Directory of Open Access Journals (Sweden)

    César Augusto Parra Aldana

    2011-12-01

    Full Text Available Colombobalanus excelsa es una especie endémica de la zona andina de Colombia, con cuatro poblaciones aisladas que forman rodales homogéneos denominados robledales negros. Se encuentra en categoría vulnerable de amenaza, debido principalmente a la conversión del bosque para usos agropecuarios; observaciones en campo indican que la regeneración natural bajo su propia cobertura es escasa. Se propone responder las siguientes preguntas: 1. ¿La estructura del bosque evidencia deficiencias en la regeneración natural de dos poblaciones de roble negro localizadas en la cordillera oriental de los Andes? 2. ¿El reclutamiento de fhmoreno@unal.edu.co está limitado por la disponibilidad y viabilidad de las semillas en las dos poblaciones estudiadas? Con este objetivo se establecieron 16 transectos permanentes de 0,1 ha para evaluar la estructura de adultos (DAP>10 cm y de la regeneración natural. Durante un año se realizó monitoreo sobre las épocas de fructificación, lluvia de semillas, germinación y banco de semillas. Los resultados muestran un suministro extremadamente bajo de renuevos y propágulos de roble negro, lo cual potencialmente puede poner en riesgo la persistencia de estos bosques. Esta situación obedece a diversos factores involucrados en el proceso de regeneración: desde baja producción de semillas de los árboles adultos, altos niveles de depredación pre-dispersión, alta proporción de semillas vacías, baja viabilidad de las semillas sanas, hasta alta mortalidad de las semillas sanas y viables que llegan al suelo. Si bien todos estos factores actúan en cascada, el último de ellos es quizás el que ejerce un efecto más dramático en el bajo éxito reproductivo de esta especie.Colombobalanus excelsa is an endemic species of the Andean region of Colombia, with four isolated populations, forming pure stands called black oak forests. It has been classified in the threat category ''Vulnerable'', mainly due to conversion of

  10. Evolución de las cuencas sinorogénicas de la Cordillera Principal entre 35°- 36° S, Malargüe Evolution of the foreland basins in the Cordillera Principal, at 35º - 36º S. Malargüe

    Directory of Open Access Journals (Sweden)

    J. Silvestro

    2005-12-01

    Full Text Available La faja plegada y corrida de Malargüe se encuentra localizada en el extremo sur de la Cordillera Principal a los 35°-36° S. Los estratos de crecimiento preservados en cuencas sintectónicas registraron la cinemática de plegamiento de la faja plegada durante el Cenozoico. La cuenca Pinchera-Ventana, ubicada en el sector oeste del área, está rellena por dos secuencias volcaniclásticas cubiertas por basaltos. En el sector occidental de esta cuenca, las secuencias se adelgazan hacia los anticlinales de La Valenciana y Torrecillas en el oeste y hacia los retrocorrimientos de La Brea en el este, desarrollando discordancias progresivas observadas en el campo. En el sector oriental de la cuenca, el arreglo de facies, la composición de los clastos y la presencia de discordancias sugieren una proveniencia desde el anticlinal Bardas Blancas en el oeste. Dataciones radimétricas de los niveles andesíticos basales (15,1 Ma y de los basaltos al techo (6,7 Ma limitan la edad de esta cuenca al Mioceno medio y superior. La cuenca Malargüe desarrollada en el sector oriental del área de estudio, está rellena por dos secuencias sintectónicas volcaniclásticas, cubiertas por una secuencia postectónica. El análisis sísmico de las secuencias de crecimiento muestra un arreglo divergente relacionado al levantamiento del anticlinal Malargüe en el oeste de la cuenca y un triángulo de crecimiento hacia el este relacionado al levantamiento del anticlinal Chacay. La datación de niveles andesíticos basales en 5,04 Ma y la secuencia postectónica al tope, limitan la edad de la cuenca entre el Mioceno superior y Cuaternario. Estas observaciones indican que los depocentros sedimentarios migraron hacia el antepaís conjuntamente con el avance de la faja plegada en igual sentido.The Andean fold-and-thrust belt of Malargüe is located in the foothills of Cordillera Principal at 35º-36º S. The geometry and age of the growth strata preserved in syntectonic

  11. Strong lateral strength contrasts in the mantle lithosphere of continents: A case study from the hot SW Canadian Cordillera

    NARCIS (Netherlands)

    Hardebol, N.J.; Beekman, F.; Cloetingh, S.A.P.L.

    2013-01-01

    This study aims at quantifying the 3-D variability in lithosphere strength of the south-eastern Canadian Cordillera and adjacent craton to the east. Strength is calculated in a forward manner, starting from rheological laws of brittle and ductile deformation. The work flow calculates a temperature m

  12. Polychlorinated dibenzo-p-dioxin and dibenzofuran in urban air of an Andean city.

    Science.gov (United States)

    Aristizábal, B H; Gonzalez, C M; Morales, L; Abalos, M; Abad, E

    2011-09-01

    Particle-bound polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in ambient air were monitored together with particulate matter less than 10 μm (PM(10)) at three sampling sites of the Andean city of Manizales, Colombia; during September 2009 and July 2010. PCDD/Fs ambient air emissions ranged from 1 fg WHO-TEQ m(-3) to 52 fg WHO-TEQ m(-3) in particulate fraction. The PM(10) concentrations ranged from 23 μg m(-3) to 54 μg m(-3). Concentrations of PM(10) and PCDD/Fs in ambient air observed for Manizales - a medium sized city with a population of 380,000 - were comparable to concentrations in larger cities. The highest concentrations of PCDD/Fs and PM(10) found in this study were determined at the central zone of the city, characterized by public transportation density, where diesel as principal fuel is used. In addition, hypothetical gas fractions of PCDD/Fs were calculated from theoretical K(p) data. Congener profiles of PCDD/Fs exhibited ratios associated with different combustion sources at the different sampling locations, ranging from steel recycling to gasoline and diesel engines. Taking into account particle and gas hypothetical fraction of PCDD/Fs, Manizales exhibited values of PCDD/Fs equivalent to rural and urban-industrial sites in the southeast and center of the city respectively. Poor correlation of PCDDs with PM(10) (r=-0.55 and r=0.52) suggests ambient air PCDDs were derived from various combustion sources. Stronger correlation was observed of PCDFs with PM(10). Poor correlation between precipitation and reduced PM(10) concentration in ambient air (r=-0.45) suggested low PM(10) removal by rainfall.

  13. Brain blood flow in Andean and Himalayan high-altitude populations: evidence of different traits for the same environmental constraint

    NARCIS (Netherlands)

    G.F.A. Jansen; B. Basnyat

    2011-01-01

    Humans have populated the Tibetan plateau much longer than the Andean Altiplano. It is thought that the difference in length of occupation of these altitudes has led to different responses to the stress of hypoxia. As such, Andean populations have higher hematocrit levels than Himalayans. In contras

  14. Ultraviolet-B-driven pigmentation and genetic diversity of benthic macroinvertebrates from high-altitude Andean streams

    NARCIS (Netherlands)

    R.A. Loayza Muro; J.K. Marticorena-Ruíz; E.J. Palomino; C Merrit; J.A.J. Breeuwer; P. Kuperus; M.H.S. Kraak; W. Admiraal

    2013-01-01

    Photoprotective pigments in benthic macroinvertebrates may reduce the damage caused by the blistering UV-B radiation in Andean high-altitude streams above 3500 m. The aim of this study was therefore to determine whether melanisation in macroinvertebrates inhabiting high-altitude Andean streams is an

  15. Transference of some microsatellite molecular markers from Fabaceae family to Andean Lupin (Lupinus mutabilis Sweet

    Directory of Open Access Journals (Sweden)

    Michelle C. Chirinos-Arias

    2015-03-01

    Full Text Available In order to analyze transferibility of 15 microsatellite primers from Fabaceae family to Lupinus mutabilis Sweet "andean lupine" chosen to present transferability between species and genera, by its high rate of polymorphic content (PIC and high degree of observed and expected heterozygosity. DNA was extracted of 300 andean lupines plants, PCR conditions were standardized by gradients of master mix components. Primers for screening were run on 3% agarose gel with some samples. Finally population was amplified and run on 6% polyacrylamide gel for its highest resolution. Only 6.67% of primers were amplified, but they were monomorphic, so they cannot be used for molecular characterization. We proposed eight microsatellite primers for andean lupin wich should be probed in laboratory conditions.

  16. Lichenometric Dating of Little Ice Age Moraines in the Cordillera Vilcabamba, Southern Peruvian Andes

    Science.gov (United States)

    Taggart, J. R.; Licciardi, J. M.

    2008-12-01

    Lateral and end moraines deposited by two valley glaciers were mapped on the south side of Nevado Tucarhuay (5910 m asl) and on the east side of Nevado Salcantay (6271 m asl) in the Cordillera Vilcabamba in the southern Peruvian Andes (~13°S latitude). The geomorphic expression of outer and inner moraine sequences in these two drainages mimics that of a previously studied pair of moraines in the upper Rio Blanco valley on the south side of Nevado Salcantay. Cosmogenic 10Be surface exposure dating has yielded ages of 9.0 ± 0.3 ka and 195 ± 24 years, respectively, for these outer and inner Rio Blanco moraines. In all three valleys, prominent outer moraines occur ~3-5 km from headwalls and inner moraine ridges are found ~2.5-3 km from headwalls. Recessional moraines found exclusively on the east side of Salcantay indicate multiple early- to late-Holocene glacier pauses, rather than continuous retreat, prior to the latest Holocene glacier readvance. Diameters of the lichen Rhizocarpon subgenus Rhizocarpon were measured on moraine boulders from the inner moraines in all three valleys. Lichen diameters on the two undated inner moraines are consistent with diameters on the inner 10Be-dated Rio Blanco moraine, which signifies similar lichenometric ages and supports synchronous glacier culminations in all three drainages during the Little Ice Age. The new lichen measurements and age estimates provide a critical link between previous lichen studies in the Cordillera Blanca to the north and in the Cordillera Real to the south, thereby increasing spatial coverage of terrestrial paleoclimate information. Moreover, the extensive lichen measurements gathered on the inner 10Be-dated Rio Blanco moraine define a new control point for the Rhizocarpon subgenus Rhizocarpon growth curve in the tropical Peruvian- Bolivian Andes, which will increase the accuracy of lichenometric age estimates in this region. 10Be exposure dating of the inner moraines in adjacent valleys is underway

  17. Diverging Responses of Tropical Andean Biomes under Future Climate Conditions

    Science.gov (United States)

    Tovar, Carolina; Arnillas, Carlos Alberto; Cuesta, Francisco; Buytaert, Wouter

    2013-01-01

    Observations and projections for mountain regions show a strong tendency towards upslope displacement of their biomes under future climate conditions. Because of their climatic and topographic heterogeneity, a more complex response is expected for biodiversity hotspots such as tropical mountain regions. This study analyzes potential changes in the distribution of biomes in the Tropical Andes and identifies target areas for conservation. Biome distribution models were developed using logistic regressions. These models were then coupled to an ensemble of 8 global climate models to project future distribution of the Andean biomes and their uncertainties. We analysed projected changes in extent and elevational range and identified regions most prone to change. Our results show a heterogeneous response to climate change. Although the wetter biomes exhibit an upslope displacement of both the upper and the lower boundaries as expected, most dry biomes tend to show downslope expansion. Despite important losses being projected for several biomes, projections suggest that between 74.8% and 83.1% of the current total Tropical Andes will remain stable, depending on the emission scenario and time horizon. Between 3.3% and 7.6% of the study area is projected to change, mostly towards an increase in vertical structure. For the remaining area (13.1%–17.4%), there is no agreement between model projections. These results challenge the common believe that climate change will lead to an upslope displacement of biome boundaries in mountain regions. Instead, our models project diverging responses, including downslope expansion and large areas projected to remain stable. Lastly, a significant part of the area expected to change is already affected by land use changes, which has important implications for management. This, and the inclusion of a comprehensive uncertainty analysis, will help to inform conservation strategies in the Tropical Andes, and to guide similar assessments for

  18. [Structural recovering in Andean successional forests from Porce (Antioquia, Colombia)].

    Science.gov (United States)

    Yepes, Adriana P; del Valle, Jorge I; Jaramillo, Sandra L; Orrego, Sergio A

    2010-03-01

    Places subjected to natural or human disturbance can recover forest through an ecological process called secondary succession. Tropical succession is affected by factors such as disturbances, distance from original forest, surface configuration and local climate. These factors determine the composition of species and the time trend of the succession itself. We studied succession in soils used for cattle ranching over various decades in the Porce Region of Colombia (Andean Colombian forests). A set of twenty five permanent plots was measured, including nine plots (20 x 50 m) in primary forests and sixteen (20 x 25 m) in secondary forests. All trees with diameter > or =1.0 cm were measured. We analyzed stem density, basal area, above-ground biomass and species richness, in a successional process of ca. 43 years, and in primary forests. The secondary forests' age was estimated in previous studies, using radiocarbon dating, aerial photographs and a high-resolution satellite image analysis (7 to >43 years). In total, 1,143 and 1,766 stems were measured in primary and secondary forests, respectively. Basal area (5.7 to 85.4 m2 ha(-1)), above-ground biomass (19.1 to 1,011.5 t ha(-1)) and species richness (4 to 69) directly increased with site age, while steam density decreased (3,180 to 590). Diametric distributions were "J-inverted" for primary forests and even-aged size-class structures for secondary forests. Three species of palms were abundant and exclusive in old secondary forests and primary forests: Oenocarpus mapora, Euterpe precatoria and Oenocarpus bataua. These palms happened in cohorts after forest disturbances. Secondary forest structure was 40% in more than 43 years of forest succession and indicate that many factors are interacting and affecting the forests succession in the area (e.g. agriculture, cattle ranching, mining, etc.). PMID:20411733

  19. Diverging responses of tropical Andean biomes under future climate conditions.

    Science.gov (United States)

    Tovar, Carolina; Arnillas, Carlos Alberto; Cuesta, Francisco; Buytaert, Wouter

    2013-01-01

    Observations and projections for mountain regions show a strong tendency towards upslope displacement of their biomes under future climate conditions. Because of their climatic and topographic heterogeneity, a more complex response is expected for biodiversity hotspots such as tropical mountain regions. This study analyzes potential changes in the distribution of biomes in the Tropical Andes and identifies target areas for conservation. Biome distribution models were developed using logistic regressions. These models were then coupled to an ensemble of 8 global climate models to project future distribution of the Andean biomes and their uncertainties. We analysed projected changes in extent and elevational range and identified regions most prone to change. Our results show a heterogeneous response to climate change. Although the wetter biomes exhibit an upslope displacement of both the upper and the lower boundaries as expected, most dry biomes tend to show downslope expansion. Despite important losses being projected for several biomes, projections suggest that between 74.8% and 83.1% of the current total Tropical Andes will remain stable, depending on the emission scenario and time horizon. Between 3.3% and 7.6% of the study area is projected to change, mostly towards an increase in vertical structure. For the remaining area (13.1%-17.4%), there is no agreement between model projections. These results challenge the common believe that climate change will lead to an upslope displacement of biome boundaries in mountain regions. Instead, our models project diverging responses, including downslope expansion and large areas projected to remain stable. Lastly, a significant part of the area expected to change is already affected by land use changes, which has important implications for management. This, and the inclusion of a comprehensive uncertainty analysis, will help to inform conservation strategies in the Tropical Andes, and to guide similar assessments for other

  20. Edge Influence on Diversity of Orchids in Andean Cloud Forests

    Directory of Open Access Journals (Sweden)

    Edicson Parra Sánchez

    2016-03-01

    Full Text Available Cloud forests harbor high levels of orchid diversity. However, due to the high fragmentation of these forests in the Andes, combined with the pressure for new agricultural land, orchid diversity is highly threatened. Despite this worrying scenario, few studies have assessed the effects of habitat loss specifically on orchid assemblages in the Andes. The aim of this study was to analyze the edge effect on orchids in cloud forest fragments of varying size. We measured forest structure, neighboring land cover and edge effect on orchid abundance, species richness and beta-diversity, by sampling assemblages along edge-to-interior transects in six different sized Andean (southwest Colombia forest remnants. We recorded 11,127 stem-individuals of orchids in 141 species. Within the forest, edges sustained equal or more species than interior plots. Our results revealed neither patch metrics nor forest structure showed any significant association to orchid diversity at any scale. Nonetheless, from our observations in composition, the type of neighboring cover, particularly pastures, negatively influences interior species (richness and composition in larger reserves. This might be due to the fact that some species found in interior plots tend to be confined, with sporadic appearances in regeneration forest and are very scarce or absent in pastures. Species richness differed significantly between matrix types. Our results suggest that (1 orchid diversity shows spatial variability in response to disturbances, but the response is independent from forest structure, patch size and patch geometry; (2 orchid communities are negatively affected by covers, and this pattern is reflected in reduced richness and high species turnover; (3 orchid richness edge effect across a pasture-interior gradient. Two forest management implications can be discerned from our results: (1 management strategies aiming to reduce edge effects may focus on improvement regeneration

  1. Andean grasslands are as productive as tropical cloud forests

    Science.gov (United States)

    Oliveras, I.; Girardin, C.; Doughty, C. E.; Cahuana, N.; Arenas, C. E.; Oliver, V.; Huaraca Huasco, W.; Malhi, Y.

    2014-11-01

    We aim to assess net primary productivity (NPP) and carbon cycling in Andean tropical alpine grasslands (puna) and compare it with NPP of tropical montane cloud forests. We ask the following questions: (1) how do NPP and soil respiration of grasslands vary over the seasonal cycle? (2) how do burning and grazing affect puna productivity? (3) if the montane forest expands into the puna, what will be the resulting change in productivity? The study sites are located at the South-eastern Peruvian Andes; one grassland site and the forest sites are in Wayqecha biological station, and another grassland site in Manu National Park. At each grassland site, we selected a burnt and an unburnt area, installed unfenced and fenced transects in each area, and monitored above-ground productivity (NPPAG), below-ground productivity (NPPBG) and soil respiration (Rs) for 2 yr. In the forest, we monitored NPPAG, NPPBG and Rs for 2-4 yr. Grassland NPP varied between 4.6 ± 0.25 (disturbed areas) to 15.3 ± 0.9 Mg C ha-1 yr-1 (undisturbed areas) and cloud forest NPP was between 7.05 ± 0.39 and 8.0 ± 0.47 Mg C ha-1 yr-1, while soil carbon stocks were in the range of 126 ± 22 to 285 ± 31 Mg C ha-1. There were no significant differences on NPP between the puna and forest sites. The most undisturbed site had significantly higher NPP than other grassland sites, but no differences were found when relating grazing and fire at other sites. There were lower residence times of above-ground biomass compared to below-ground biomass. There was a strong seasonal signal on grassland NPPAG and NPPBG, with a shift on allocation at the beginning of the austral summer. High elevation tropical grasslands can be as productive as adjacent cloud forests, but have very different carbon cycling and retention properties than cloud forests.

  2. Influence of cranial deformation on facial morphology among prehistoric South Central Andean populations.

    Science.gov (United States)

    Rhode, Matthew P; Arriaza, Bernardo T

    2006-08-01

    Calculating biodistances among South American populations using cranial measurements is often hindered, as many available skeletal collections exhibit deformation. Acknowledging vault modifications, researchers have sought measurements in other regions which are unaffected by deformation. In the 1970s, a set of 10 "relatively" unaffected facial measurements was identified in Argentinean crania that later became the basis of numerous South American biodistance studies. These measurements include: minimum frontal breadth, bizygomatic breadth, orbit height, orbit breadth, palate breath, palate length, upper facial height, basion-prosthion length, nasal height, and nasal breadth. Palate length was excluded from the present analysis due to considerable measurement error. The suitability of these measurements in populations other than Argentineans has not been rigorously tested. Using a sample of 350 prehistoric crania from the Museo Arqueológico San Miguel de Azapa (MASMA, Arica, Chile), this project tested the hypothesis that these measurements are unaffected by either annular or tabular deformation. Results obtained from MANOVA analysis indicate this hypothesis cannot be fully supported. Among males, only 3 of the 9 measurements are unaffected by either form of deformation (palate breadth, basion-prosthion length, and nasal breadth), while analysis of females indicates that 4 of the 9 measurements remain unaltered (minimum frontal breadth, orbit breadth, basion-prosthion length, and nasal breadth). Additionally, analogous to the vault, facial measurements display patterns consistent with the deformation applied. Two implications can be drawn from this research: 1) previous studies using these measurements must be interpreted cautiously, and 2) researchers using these measurements must explicitly test their suitability in each population.

  3. Remains of early Ordovician mantle-derived magmatism in the Santander Massif (Colombian Eastern Cordillera)

    Science.gov (United States)

    Mantilla Figueroa, Luis C.; Bissig, Thomas; Cottle, John M.; Hart, Craig J. R.

    2012-10-01

    An Early Ordovician magmatic event has been documented in the Santander Massif (north-Eastern Cordillera, Colombia). Three U/Pb laser ablation ages of 477 ± 2 Ma (Arenig), were obtained from metamorphosed and foliated calc-alkaline diorites. The 176Hf/177Hf values in zircons from these meta-diorites, yielded epsilon Hf values (ɛHft) > 0 (Mean = 2 ± 1, at 477 Ma). These data allow interpretation of the origin of these zircons from a radiogenic initial Hf isotope source, which is characteristic of the Earth's mantle. This, together with the fact that the rocks have been affected subsequently by tectonometamorphic processes, suggests that the early Ordovician diorites have been emplaced in a supra-subduction tectonic setting, related to onset of the Iapetus Ocean closure.

  4. Precambrian crust beneath the Mesozoic northern Canadian Cordillera discovered by Lithoprobe seismic reflection profiling

    Science.gov (United States)

    Cook, Frederick A.; Clowes, Ronald M.; Snyder, David B.; van der Velden, Arie J.; Hall, Kevin W.; Erdmer, Philippe; Evenchick, Carol A.

    2004-04-01

    The Cordillera in northern Canada is underlain by westward tapering layers that can be followed from outcrops of Proterozoic strata in the Foreland belt to the lowermost crust of the orogenic interior, a distance of as much as 500 km across strike. They are interpreted as stratified Proterozoic rocks, including ˜1.8-0.7 Ga supracrustal rocks and their basement. The layering was discovered on two new deep seismic reflection profiles in the Yukon (Line 3; ˜650 km) and northern British Columbia (Line 2; ˜1245 km in two segments) that were acquired as part of the Lithoprobe Slave-Northern Cordillera Lithospheric Evolution (SNORCLE) transect. In the Mackenzie Mountains of the eastern Yukon, the layering in Line 3 is visible between 5.0 and 12.0 s (˜15 to 36 km depth). It is followed southwestward for nearly 650 km (˜500 km across strike) and thins to less than 1.0 s (˜3.0-3.5 km thickness) near the Moho at the Yukon-Alaska international boundary. In the northern Rocky Mountains of British Columbia, the upper part of the layering on Line 2 correlates with outcrops of Proterozoic (1.76-1.0 Ga) strata in the Muskwa anticlinorium. At this location, the layering is at least 15 km thick and is followed westward then southward into the middle and lower crust for ˜700 km (˜300 km across strike). It disappears as a thin taper at the base of the crust ˜150 km east of the coast of the Alaskan panhandle. The only significant disruption in the layering occurs at the Tintina fault zone, a late to postorogenic strike-slip fault with up to 800 km of displacement, which appears as a vertical zone of little reflectivity that disrupts the continuity of the deep layering on both profiles (˜300 km apart). The base of the layered reflection zone coincides with the Moho, which exhibits variable character and undulates in a series of broad arches with widths of ˜150 km. In general, the mantle appears to have few reflections. However, at the southwest end of Line 3 near the Alaska

  5. Holocene Paleoglacier History of Glaciar Dalla Vedova, Cordillera DARWIN, Tierra del Fuego, Chile

    Science.gov (United States)

    Reynhout, S.

    2015-12-01

    Southernmost South America is unique in its position immediately north of the present-day Antarctic Convergence, making it ideally suited for the evaluation of Antarctic influences on terrestrial paleoclimate. Here we present a glacial geomorphic interpretation of the paleoglacial history of Glaciar Dalla Vedova in Bahía Blanca, Cordillera Darwin, Chile (53°S). This interpretation is further constrained by radiocarbon dating, cosmogenic dating, dendrochronology, and historical photogrammetry. Preliminary field work suggests that Holocene glacier fluctuations have been constrained to within 3 km of the present glacier boundary, punctuated by rapid recent glacier retreat over the past century. By comparing the observed chronology with the record contained further north in Patagonia, we will evaluate possible mechanisms of regional climate variability over the Holocene across southernmost South America.

  6. Timing and Style of Deformation in the Floresta Massif, Axial Eastern Cordillera, Colombia

    Science.gov (United States)

    Saylor, J.; Stockli, D. F.; Mora, A.

    2009-12-01

    The Floresta Massif is one of the largest exposures of Paleozoic and Pre-Cambrian rocks in the Eastern Cordillera. Estimates for the age of onset of shortening-related deformation in the Eastern Cordillera range from late Cretaceous to late Miocene (e.g., Hoorn et al., 1995; Bayona et al., 2008; Parra et al., 2009). The massif is typically interpreted as being exhumed along a high-angle reverse fault (the Soapaga fault) that reactivated Mesozoic extensional structures (e.g., Kammer and Sanchez, 2006). We examined these dual linked issued with new zircon U/Th-He (ZHe) data, new geological mapping and previously published apatite fission track (AFT) data from the Floresta Massif and the associated footwall strata. Previously, an overturned Paleozoic - Cretaceous sequence was mapped emplaced on Tertiary strata along the Soapaga fault. However, new geologic mapping identifies two previously unrecognized thrusts which place, from west to east, Paleozoic strata on Jurassic strata (Fault 3), Jurassic strata on Cretaceous strata (Fault 2) and Cretaceous strata on Tertiary strata (along the previously identified Fault 1). These results are confirmed by AFT and ZHe data. ZHe ages show no resetting in the Tertiary footwall strata, but show partial resetting in the Cretaceous strata and full resetting in the Jurassic and Paleozoic strata. Similarly, AFT data show older ages in the Cretaceous strata than in the Jurassic or Paleozoic strata. Fully reset ZHe ages from Jurassic strata show that exhumation of the Floresta Massif was ongoing by at least the early Oligocene (~ 30 Ma). However, this deformation post-dates an older episode of deformation associated with partially reset ZHe ages in the Cretaceous strata. Based on a decrease in lag time in detrital ZHe data, we infer that the earlier episode of deformation occurred in the mid - late Eocene (45 - 35 Ma).

  7. Ethno-botanical survey of edible wild fruits in Benguet, Cordillera administrative region, the Philippines

    Institute of Scientific and Technical Information of China (English)

    Racquel Tan Chua-Barcelo

    2014-01-01

    Objective: To conduct a survey on the common name/s, traditional uses and cultural importance of the edible wild fruits in different municipalities of Benguet, Cordillera administrative region. Methods: Interviews using questionnaires with barangay leaders and indigenous people were conducted with 176 key informants from June 2011 to July 2013. Results: A total of 36 fruit species were found in different municipalities of Benguet. These fruit species belong to 27 genera and 20 families. Among the 13 municipalities of Benguet, Kibungan has the highest number of species. There are many uses of wild fruits which ranged from food (snack/dessert/table food), forage (especially for birds, monkeys and wild animals such as cloud rat and grass eaters), offertory, processed/preserved (as jam, jellies, candies, juice and wine), condiment or ingredient (for cooking), source of dye or ink, decoration (to garnish food) and as medicine to common ailments or health problems. Based on the inventory and calculated cultural importance index, Garcinia binucao (balokok) belonging to Clusiaceae is the most abundant fruit, hence it is the commonly used fruit for various purposes such as food, forage, processing/preservation and condiment/ingredient; Vaccinium myrtoides (ayusip) for offerings and as source of dye/ink; Saurauia elegans (uyok) for decoration, and, Antidesma bunius (bugnay) for medicine. Conclusions: Benguet province in the Cordillera region provides a diversity of edible wild fruits. The data gathered from the study signifies that collection, processing and utilization of edible wild fruits are still part of the daily activities of the people in Benguet.

  8. Graptolitos ordovícicos en el Sur de la Cordillera frontal de Mendoza

    Directory of Open Access Journals (Sweden)

    Hugo Tickyj

    2009-04-01

    Full Text Available En el flanco sudoriental de la Cordillera Frontal mendocina aflora un conjunto plegado de metasedimentitas conocido como Formación Las Lagunitas, cuyos afloramientos se extienden entre los ríos Diamante por el sur y Tunuyán por el norte, alcanzando un ancho máximo de 15 km a la latitud del volcán Maipo. El perfil estudiado en el arroyo Cortaderas (34º23'S está compuesto por una secuencia silicoclástica marina integrada por tres conjuntos litológicos, que de este a oeste son: a areniscas gruesas a medias, bien seleccionadas, y areniscas conglomerádicas, b vaques de grano grueso a fino y c areniscas finas a medias, con intercalaciones de pelitas negras laminadas. En la última unidad fueron colectados graptolitos en regular estado de preservación. Su estudio sistemático permitió definir una asociación correspondiente a la Biozona de Climacograptus bicornis, por lo que la Formación Las Lagunitas es asignada al Ordovícico Superior (Sandbiano o Caradociano. La completa extensión cronoestratigráfica de la Formación Las Lagunitas no ha sido establecida, debido a que en el perfil estudiado no es clara la relación entre la unidad portadora de graptolitos y el resto de la secuencia. Este registro de graptolitos en el sur de la Cordillera Frontal mendocina constituye un aspecto novedoso para el análisis del Ordovícico, con implicancias en el contexto de la evolución tectónica de las cuencas sedimentarias ordovícicas del oeste argentino.

  9. Crustal structure of the western transect of the Rif Cordillera from broadband magnetotelluric data

    International Nuclear Information System (INIS)

    Complete text of publication follows. Within the frame of the Topo-Iberia project, the magnetotelluric method has been applied for first time in the western transect of the Rif Cordillera to delineate the electrical crustal structure. Data acquisition has been done in 18 MT measurement sites, with ADU-07 Metronix equipment, including vertical magnetic records. Frequencies range from 4Hz to 32 kHz and acquisition time on each site was from two to three days. The profile extends approximately 110 km in NE-SW trend orthogonal to the main regional geological structures, crossing from the Alboran Sea coast through the major alpine units of the western Rif Cordillera up to the foreland Gharb basin. We have performed a dimensionality analysis using the Wal's and the Bahr's methods, both based on the rotational invariants. The data obtained show variable dimensionalities ranging from 1D to 3D. Predominant strikes suggest NW-SE orientations. Therefore several 2D models have processed using Winglink software with different rotations. The model with N145 deg E rotation shows a good correlation between the resistive structures and the surface geology, as well as their continuity in depth. The Internal Zones corresponds generally to resistive rocks (metamorphic rocks) including a significant conductive body that probably corresponds to the nearby outcropping Beni Boussera peridotites. The External Zones and the foreland basin are characterized by shallow heterogeneous conductive structures. In depth, the most relevant feature corresponds to a large resistive body located below the frontal part of the Rif. The presence of exotic gneiss blocks in the front of the External Zones suggests that this large deep body may correspond to a gneissic or granitic basement surrounded by metapelitic rocks. The deep structure of this transect contributes to highlight the recent evolution and development of the southern part of the Gibraltar Arch in the frame of the Eurasian-African convergent

  10. Assessment of satellite rainfall products over the Andean plateau

    Science.gov (United States)

    Satgé, Frédéric; Bonnet, Marie-Paule; Gosset, Marielle; Molina, Jorge; Hernan Yuque Lima, Wilson; Pillco Zolá, Ramiro; Timouk, Franck; Garnier, Jérémie

    2016-01-01

    Nine satellite rainfall estimations (SREs) were evaluated for the first time over the South American Andean plateau watershed by comparison with rain gauge data acquired between 2005 and 2007. The comparisons were carried out at the annual, monthly and daily time steps. All SREs reproduce the salient pattern of the annual rain field, with a marked north-south gradient and a lighter east-west gradient. However, the intensity of the gradient differs among SREs: it is well marked in the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis 3B42 (TMPA-3B42), Precipitation Estimation from remotely Sensed Information using Artificial Neural Networks (PERSIANN) and Global Satellite Mapping of Precipitation (GSMaP) products, and it is smoothed out in the Climate prediction center MORPHing (CMORPH) products. Another interesting difference among products is the contrast in rainfall amounts between the water surfaces (Lake Titicaca) and the surrounding land. Some products (TMPA-3B42, PERSIANN and GSMaP) show a contradictory rainfall deficit over Lake Titicaca, which may be due to the emissivity contrast between the lake and the surrounding lands and warm rain cloud processes. An analysis differentiating coastal Lake Titicaca from inland pixels confirmed this trend. The raw or Real Time (RT) products have strong biases over the study region. These biases are strongly positive for PERSIANN (above 90%), moderately positive for TMPA-3B42 (28%), strongly negative for CMORPH (- 42%) and moderately negative for GSMaP (- 18%). The biases are associated with a deformation of the rain rate frequency distribution: GSMaP underestimates the proportion of rainfall events for all rain rates; CMORPH overestimates the proportion of rain rates below 2 mm day- 1; and the other products tend to overestimate the proportion of moderate to high rain rates. These biases are greatly reduced by the gauge adjustment in the TMPA-3B42, PERSIANN and CMORPH products, whereas a

  11. Genetic admixture and lineage separation in a southern Andean plant

    Science.gov (United States)

    Morello, Santiago; Sede, Silvana M.

    2016-01-01

    Mountain uplifts have generated new ecologic opportunities for plants, and triggered evolutionary processes, favouring an increase on the speciation rate in all continents. Moreover, mountain ranges may act as corridors or barriers for plant lineages and populations. In South America a high rate of diversification has been linked to Andean orogeny during Pliocene/Miocene. More recently, Pleistocene glacial cycles have also shaped species distribution and demography. The endemic genus Escallonia is known to have diversified in the Andes. Species with similar morphology obscure species delimitation and plants with intermediate characters occur naturally. The aim of this study is to characterize genetic variation and structure of two widespread species of Escallonia: E. alpina and E. rubra. We analyzed the genetic variation of populations of the entire distribution range of the species and we also included those with intermediate morphological characters; a total of 94 accessions from 14 populations were used for the Amplified Fragment Length Polymorphism (AFLP) analysis. Plastid DNA sequences (trnS-trnG, 3′trnV-ndhC intergenic spacers and the ndhF gene) from sixteen accessions of Escallonia species were used to construct a Statistical Parsimony network. Additionally, we performed a geometric morphometrics analysis on 88 leaves from 35 individuals of the two E. alpina varieties to further study their differences. Wright’s Fst and analysis of molecular variance tests performed on AFLP data showed a significant level of genetic structure at the species and population levels. Intermediate morphology populations showed a mixed genetic contribution from E. alpina var. alpina and E. rubra both in the Principal Coordinates Analysis (PCoA) and STRUCTURE. On the other hand, E. rubra and the two varieties of E. alpina are well differentiated and assigned to different genetic clusters. Moreover, the Statistical Parsimony network showed a high degree of divergence between the

  12. Characterization of Two Microbial Isolates from Andean Lakes in Bolivia

    Science.gov (United States)

    Demergasso, C.; Blamey, J.; Escudero, L.; Chong, G.; Casamayor, E. O.; Cabrol, N. A.; Grin, E. A.; Hock, A.; Kiss, A.; Borics, G.

    2004-01-01

    We are currently investigating the biological population present in the highest and least explored perennial lakes on earth in the Bolivian and Chilean Andes, including several volcanic crater lakes of more than 6000 m elevation, in combination of microbiological and molecular biological methods. Our samples were collected in saline lakes of the Laguna Blanca Laguna Verde area in the Bolivian Altiplano and in the Licancabur volcano crater (27 deg. 47 min S/67 deg. 47 min. W) in the ongoing project studying high altitude lakes. The main goal of the project is to look for analogies with Martian paleolakes. These Bolivian lakes can be described as Andean lakes following the classification of Chong. We have attempted to isolate pure cultures and phylogenetically characterize prokaryotes that grew under laboratory conditions. Sediment samples taken from the Licancabur crater lake (LC), Laguna Verde (LV), and Laguna Blanca (LB) were analyzed and cultured using enriched liquid media under both aerobic and anaerobic conditions. All cultures were incubated at room temperature (15 to 20 C) and under light exposure. For the reported isolates, 36 hours incubation were necessary for reaching optimal optical densities to consider them viable cultures. Ten serial dilutions starting from 1% inoculum were required to obtain a suitable enriched cell culture to transfer into solid media. Cultures on solid medium were necessary to verify the formation of colonies in order to isolate pure cultures. Different solid media were prepared using several combinations of both trace minerals and carbohydrates sources in order to fit their nutrient requirements. The microorganisms formed individual colonies on solid media enriched with tryptone, yeast extract and sodium chloride. Cells morphology was studied by optical and electronic microscopy. Rodshape morphologies were observed in most cases. Total bacterial genomic DNA was isolated from 50 ml late-exponential phase culture by using the CTAB

  13. Andean grasslands are as productive as tropical cloud forests

    International Nuclear Information System (INIS)

    We aim to assess net primary productivity (NPP) and carbon cycling in Andean tropical alpine grasslands (puna) and compare it with NPP of tropical montane cloud forests. We ask the following questions: (1) how do NPP and soil respiration of grasslands vary over the seasonal cycle? (2) how do burning and grazing affect puna productivity? (3) if the montane forest expands into the puna, what will be the resulting change in productivity? The study sites are located at the South-eastern Peruvian Andes; one grassland site and the forest sites are in Wayqecha biological station, and another grassland site in Manu National Park. At each grassland site, we selected a burnt and an unburnt area, installed unfenced and fenced transects in each area, and monitored above-ground productivity (NPPAG), below-ground productivity (NPPBG) and soil respiration (Rs) for 2 yr. In the forest, we monitored NPPAG, NPPBG and Rs for 2–4 yr. Grassland NPP varied between 4.6 ± 0.25 (disturbed areas) to 15.3 ± 0.9 Mg C ha−1 yr−1 (undisturbed areas) and cloud forest NPP was between 7.05 ± 0.39 and 8.0 ± 0.47 Mg C ha−1 yr−1, while soil carbon stocks were in the range of 126 ± 22 to 285 ± 31 Mg C ha−1. There were no significant differences on NPP between the puna and forest sites. The most undisturbed site had significantly higher NPP than other grassland sites, but no differences were found when relating grazing and fire at other sites. There were lower residence times of above-ground biomass compared to below-ground biomass. There was a strong seasonal signal on grassland NPPAG and NPPBG, with a shift on allocation at the beginning of the austral summer. High elevation tropical grasslands can be as productive as adjacent cloud forests, but have very different carbon cycling and retention properties than cloud forests. (paper)

  14. Forests of the tropical eastern Andean flank during the middle Pleistocene

    NARCIS (Netherlands)

    M.L. Cárdenas; W.D. Gosling; R.T. Pennington; I. Poole; S.C. Sherlock; P. Mothes

    2014-01-01

    Inter-bedded volcanic and organic sediments from Erazo (Ecuador) indicate the presence of four different forest assemblages on the eastern Andean flank during the middle Pleistocene. Radiometric dates (40Ar-39Ar) obtained from the volcanic ash indicate that deposition occurred between 620,000 and 19

  15. The electronic procurement in the framework of the Andean Community. State of the art

    Directory of Open Access Journals (Sweden)

    William David Hernández Martínez

    2010-12-01

    Full Text Available The article is structured as a brief survey of the academic and policy approach on the unification or harmonization of regulations about electronic commerce, specifically relating the electronic contracts, in Latin America, with special emphasis on the Andean Community of Nations as a proposed work on the development of modern trends of international trade law.

  16. A novel cold active esterase derived from Colombian high Andean forest soil metagenome

    NARCIS (Netherlands)

    Jiménez, Diego Javier; Montaña, José Salvador; Alvarez, Diana; Baena, Sandra

    2012-01-01

    In order to search new lipolytic enzymes and conduct bioprospecting of microbial communities from high Andean forest soil, a metagenomic library of approximately 20,000 clones was constructed in Escherichia coli using plasmid p-Bluescript II SK+. The library covered 80 Mb of the metagenomic DNA main

  17. Taxonomic and functional assignment of cloned sequences from high Andean forest soil metagenome

    NARCIS (Netherlands)

    Montaña, José Salvador; Jiménez Avella, Diego; Angel, Tatiana; Hernández, Mónica; Baena, Sandra

    2012-01-01

    Total metagenomic DNA was isolated from high Andean forest soil and subjected to taxonomical and functional composition analyses by means of clone library generation and sequencing. The obtained yield of 1.7 μg of DNA/g of soil was used to construct a metagenomic library of approximately 20,000 clon

  18. Marcos Zapata's "Last Supper": a feast of European religion and Andean culture.

    Science.gov (United States)

    Zendt, Christina

    2010-01-01

    In Marcos Zapata's 1753 painting of the Last Supper in Cuzco, Peru, Christian symbolism is filtered through Andean cultural tradition. Zapata was a late member of the Cuzco School of Painting, a group comprised of few European immigrants and handfuls of mestizo and Indian artists. The painters in Cuzco learned mostly from prints of European paintings, and their style tends to blend local culture into the traditional painting of their conquistadors. Imagery was the most successful tool used by the Spaniards in their quest to Christianize the Andean population. By teaching locals to paint Christian subjects, they were able to infuse Christianity into Andean traditions. Zapata's rendering of the Last Supper utilizes this cultural blending while staying true to the Christian symbolism within the subject. Instead of the traditional lamb, Zapata's Last Supper features a platter of cuy, or guinea pig, an Andean delicacy stocked with protein as well as cultural significance. Cuy was traditionally a sacrificial animal at Inca agricultural festivals and in this way it offers poignant parallel to the lamb, as a traditional Christian sacrificial animal. PMID:21568039

  19. Persistence of chironomids in metal polluted Andean high altitude streams: does melanin play a role?

    NARCIS (Netherlands)

    R.A. Loayza Muro; J.K. Marticorena-Ruíz; E.J. Palomino; C. Merritt; M.L. de Baat; M. van Gemert; R.A. Verweij; M.H.S. Kraak; W. Admiraal

    2013-01-01

    In high altitude Andean streams an intense solar radiation and coinciding metal pollution allow the persistence of only a few specialized taxa, including chironomids. The aim of the present study was therefore to determine the mechanisms underlying the persistence of chironomids under these multiple

  20. The Rise and Fall of Andean Empires: El Nino History Lessons.

    Science.gov (United States)

    Wright, Kenneth R.

    2000-01-01

    Provides information on El Nino and the methods for investigating ancient climate record. Traces the rise and fall of the Andean empires focusing on the climatic forces that each empire (Tiwanaku, Wari, Moche, and Inca) endured. States that modern societies should learn from the experiences of these ancient civilizations. (CMK)

  1. The abiotic and biotic drivers of rapid diversification in Andean bellflowers (Campanulaceae).

    Science.gov (United States)

    Lagomarsino, Laura P; Condamine, Fabien L; Antonelli, Alexandre; Mulch, Andreas; Davis, Charles C

    2016-06-01

    The tropical Andes of South America, the world's richest biodiversity hotspot, are home to many rapid radiations. While geological, climatic, and ecological processes collectively explain such radiations, their relative contributions are seldom examined within a single clade. We explore the contribution of these factors by applying a series of diversification models that incorporate mountain building, climate change, and trait evolution to the first dated phylogeny of Andean bellflowers (Campanulaceae: Lobelioideae). Our framework is novel for its direct incorporation of geological data on Andean uplift into a macroevolutionary model. We show that speciation and extinction are differentially influenced by abiotic factors: speciation rates rose concurrently with Andean elevation, while extinction rates decreased during global cooling. Pollination syndrome and fruit type, both biotic traits known to facilitate mutualisms, played an additional role in driving diversification. These abiotic and biotic factors resulted in one of the fastest radiations reported to date: the centropogonids, whose 550 species arose in the last 5 million yr. Our study represents a significant advance in our understanding of plant evolution in Andean cloud forests. It further highlights the power of combining phylogenetic and Earth science models to explore the interplay of geology, climate, and ecology in generating the world's biodiversity. PMID:26990796

  2. Formal Law and Local Water Control in the Andean Region: A Fiercely Contested Field

    NARCIS (Netherlands)

    Vos, de H.; Boelens, R.A.; Bustamente, R.R.

    2006-01-01

    Water access and control rights of peasant and indigenous communities in Andean countries are threatened. Vertical state law and intervention practices, as well as new privatization policies generally ignore, discriminate or undermine local normative frameworks. Recognition of diverse local rights a

  3. Institutional reform in the Andean irrigation sector: enabling policies for strengthening local rights and water management

    NARCIS (Netherlands)

    Cremers, L.; Ooijevaar, M.; Boelens, R.A.

    2005-01-01

    For centuries, local and indigenous water rights and rules in the Andean region have been largely neglected and discriminated against. The process of undermining local communities' water access and control rights continues up to today and not only is it headed by powerful local, national and interna

  4. The abiotic and biotic drivers of rapid diversification in Andean bellflowers (Campanulaceae).

    Science.gov (United States)

    Lagomarsino, Laura P; Condamine, Fabien L; Antonelli, Alexandre; Mulch, Andreas; Davis, Charles C

    2016-06-01

    The tropical Andes of South America, the world's richest biodiversity hotspot, are home to many rapid radiations. While geological, climatic, and ecological processes collectively explain such radiations, their relative contributions are seldom examined within a single clade. We explore the contribution of these factors by applying a series of diversification models that incorporate mountain building, climate change, and trait evolution to the first dated phylogeny of Andean bellflowers (Campanulaceae: Lobelioideae). Our framework is novel for its direct incorporation of geological data on Andean uplift into a macroevolutionary model. We show that speciation and extinction are differentially influenced by abiotic factors: speciation rates rose concurrently with Andean elevation, while extinction rates decreased during global cooling. Pollination syndrome and fruit type, both biotic traits known to facilitate mutualisms, played an additional role in driving diversification. These abiotic and biotic factors resulted in one of the fastest radiations reported to date: the centropogonids, whose 550 species arose in the last 5 million yr. Our study represents a significant advance in our understanding of plant evolution in Andean cloud forests. It further highlights the power of combining phylogenetic and Earth science models to explore the interplay of geology, climate, and ecology in generating the world's biodiversity.

  5. The electronic procurement in the framework of the Andean Community. State of the art

    OpenAIRE

    William David Hernández Martínez

    2010-01-01

    The article is structured as a brief survey of the academic and policy approach on the unification or harmonization of regulations about electronic commerce, specifically relating the electronic contracts, in Latin America, with special emphasis on the Andean Community of Nations as a proposed work on the development of modern trends of international trade law.

  6. Successional position of dry Andean dwarf forest species as a basis for restoration trials

    NARCIS (Netherlands)

    Groenendijk, J.P.; Duivenvoorden, J.F.; Cleef, A.M.; Rietman, N.

    2005-01-01

    The successional affinity of nine woody species was inferred from the structure, diversity and disturbance history of the vegetation where these occurred. This was done in order to obtain a basis for a restoration experiment, currently in execution, in the dry Andean dwarf forest zone on the edge of

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

    Directory of Open Access Journals (Sweden)

    MADELEINE LAMBOROT

    2001-03-01

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

  8. A new Andean lizard of the genus Potamites (Sauria, Gymnophthalmidae) from Manu National Park, southeastern Peru.

    Science.gov (United States)

    Chávez, Germán; Catenazzi, Alessandro

    2014-01-01

    We describe a new lizard of the genus Potamites from elevations of 1000-2100 m in the montane forests of the Cordillera de Paucartambo and the upper Kosñipata valley, Region of Cusco, Peru. The new species differs from other species of Potamites by having scattered keeled scales on dorsum, an undivided frontonasal and absence of femoral pores in females. PMID:24871404

  9. Crustal-thickness variations in the central Andes

    Science.gov (United States)

    Beck, Susan L.; Zandt, George; Myers, Stephen C.; Wallace, Terry C.; Silver, Paul G.; Drake, Lawrence

    1996-05-01

    We estimated the crustal thickness along an east-west transect across the Andes at lat 20°S and along a north-south transect along the eastern edge of the Altiplano from data recorded on two arrays of portable broadband seismic stations (BANJO and SEDA). Waveforms of deep regional events in the downgoing Nazca slab and teleseismic earthquakes were processed to isolate the P-to-S converted phases from the Moho in order to compute the crustal thickness. We found crustal-thickness variations of nearly 40 km across the Andes. Maximum crustal thicknesses of 70 74 km under the Western Cordillera and the Eastern Cordillera thin to 32 38 km 200 km east of the Andes in the Chaco Plain. The central Altiplano at 20°S has crustal thicknesses of 60 to 65 km. The crust also appears to thicken from north (16°S, 55 60 km) to south (20°S, 70 74 km) along the Eastern Cordillera. The Subandean zone crust has intermediate thicknesses of 43 to 47 km. Crustal-thickness predictions for the Andes based on Airy-type isostatic behavior show remarkable overall correlation with observed crustal thickness in the regions of high elevation. In contrast, at the boundary between the Eastern Cordillera and the Subandean zone and in the Chaco Plain, the crust is thinner than predicted, suggesting that the crust in these regions is supported in part by the flexural rigidity of a strong lithosphere. With additional constraints, we conclude that the observation of Airy-type isostasy is consistent with thickening associated with compressional shortening of a weak lithosphere squeezed between the stronger lithosphere of the subducting Nazca plate and the cratonic lithosphere of the Brazilian craton.

  10. Shifts in leaf litter breakdown along a forest-pasture-urban gradient in Andean streams.

    Science.gov (United States)

    Iñiguez-Armijos, Carlos; Rausche, Sirkka; Cueva, Augusta; Sánchez-Rodríguez, Aminael; Espinosa, Carlos; Breuer, Lutz

    2016-07-01

    Tropical montane ecosystems of the Andes are critically threatened by a rapid land-use change which can potentially affect stream variables, aquatic communities, and ecosystem processes such as leaf litter breakdown. However, these effects have not been sufficiently investigated in the Andean region and at high altitude locations in general. Here, we studied the influence of land use (forest-pasture-urban) on stream physico-chemical variables (e.g., water temperature, nutrient concentration, and pH), aquatic communities (macroinvertebrates and aquatic fungi) and leaf litter breakdown rates in Andean streams (southern Ecuador), and how variation in those stream physico-chemical variables affect macroinvertebrates and fungi related to leaf litter breakdown. We found that pH, water temperature, and nutrient concentration increased along the land-use gradient. Macroinvertebrate communities were significantly different between land uses. Shredder richness and abundance were lower in pasture than forest sites and totally absent in urban sites, and fungal richness and biomass were higher in forest sites than in pasture and urban sites. Leaf litter breakdown rates became slower as riparian land use changed from natural to anthropogenically disturbed conditions and were largely determined by pH, water temperature, phosphate concentration, fungal activity, and single species of leaf-shredding invertebrates. Our findings provide evidence that leaf litter breakdown in Andean streams is sensitive to riparian land-use change, with urban streams being the most affected. In addition, this study highlights the role of fungal biomass and shredder species (Phylloicus; Trichoptera and Anchytarsus; Coleoptera) on leaf litter breakdown in Andean streams and the contribution of aquatic fungi in supporting this ecosystem process when shredders are absent or present low abundance in streams affected by urbanization. Finally, we summarize important implications in terms of managing of

  11. Adaptation and mal-adaptation to ambient hypoxia; Andean, Ethiopian and Himalayan patterns.

    Directory of Open Access Journals (Sweden)

    Guoqiang Xing

    Full Text Available The study of the biology of evolution has been confined to laboratories and model organisms. However, controlled laboratory conditions are unlikely to model variations in environments that influence selection in wild populations. Thus, the study of "fitness" for survival and the genetics that influence this are best carried out in the field and in matching environments. Therefore, we studied highland populations in their native environments, to learn how they cope with ambient hypoxia. The Andeans, African highlanders and Himalayans have adapted differently to their hostile environment. Chronic mountain sickness (CMS, a loss of adaptation to altitude, is common in the Andes, occasionally found in the Himalayas; and absent from the East African altitude plateau. We compared molecular signatures (distinct patterns of gene expression of hypoxia-related genes, in white blood cells (WBC from Andeans with (n = 10, without CMS (n = 10 and sea-level controls from Lima (n = 20 with those obtained from CMS (n = 8 and controls (n = 5 Ladakhi subjects from the Tibetan altitude plateau. We further analyzed the expression of a subset of these genes in Ethiopian highlanders (n = 8. In all subjects, we performed the studies at their native altitude and after they were rendered normoxic. We identified a gene that predicted CMS in Andeans and Himalayans (PDP2. After achieving normoxia, WBC gene expression still distinguished Andean and Himalayan CMS subjects. Remarkably, analysis of the small subset of genes (n = 8 studied in all 3 highland populations showed normoxia induced gene expression changes in Andeans, but not in Ethiopians nor Himalayan controls. This is consistent with physiologic studies in which Ethiopians and Himalayans show a lack of responsiveness to hypoxia of the cerebral circulation and of the hypoxic ventilatory drive, and with the absence of CMS on the East African altitude plateau.

  12. Identifying signatures of natural selection in Tibetan and Andean populations using dense genome scan data.

    Directory of Open Access Journals (Sweden)

    Abigail Bigham

    2010-09-01

    Full Text Available High-altitude hypoxia (reduced inspired oxygen tension due to decreased barometric pressure exerts severe physiological stress on the human body. Two high-altitude regions where humans have lived for millennia are the Andean Altiplano and the Tibetan Plateau. Populations living in these regions exhibit unique circulatory, respiratory, and hematological adaptations to life at high altitude. Although these responses have been well characterized physiologically, their underlying genetic basis remains unknown. We performed a genome scan to identify genes showing evidence of adaptation to hypoxia. We looked across each chromosome to identify genomic regions with previously unknown function with respect to altitude phenotypes. In addition, groups of genes functioning in oxygen metabolism and sensing were examined to test the hypothesis that particular pathways have been involved in genetic adaptation to altitude. Applying four population genetic statistics commonly used for detecting signatures of natural selection, we identified selection-nominated candidate genes and gene regions in these two populations (Andeans and Tibetans separately. The Tibetan and Andean patterns of genetic adaptation are largely distinct from one another, with both populations showing evidence of positive natural selection in different genes or gene regions. Interestingly, one gene previously known to be important in cellular oxygen sensing, EGLN1 (also known as PHD2, shows evidence of positive selection in both Tibetans and Andeans. However, the pattern of variation for this gene differs between the two populations. Our results indicate that several key HIF-regulatory and targeted genes are responsible for adaptation to high altitude in Andeans and Tibetans, and several different chromosomal regions are implicated in the putative response to selection. These data suggest a genetic role in high-altitude adaption and provide a basis for future genotype/phenotype association

  13. Andean Condor (Vultur gryphus) in Ecuador: Geographic Distribution, Population Size and Extinction Risk.

    Science.gov (United States)

    Naveda-Rodríguez, Adrián; Vargas, Félix Hernán; Kohn, Sebastián; Zapata-Ríos, Galo

    2016-01-01

    The Andean Condor (Vultur gryphus) in Ecuador is classified as Critically Endangered. Before 2015, standardized and systematic estimates of geographic distribution, population size and structure were not available for this species, hampering the assessment of its current status and hindering the design and implementation of effective conservation actions. In this study, we performed the first quantitative assessment of geographic distribution, population size and population viability of Andean Condor in Ecuador. We used a methodological approach that included an ecological niche model to study geographic distribution, a simultaneous survey of 70 roosting sites to estimate population size and a population viability analysis (PVA) for the next 100 years. Geographic distribution in the form of extent of occurrence was 49 725 km2. During a two-day census, 93 Andean Condors were recorded and a population of 94 to 102 individuals was estimated. In this population, adult-to-immature ratio was 1:0.5. In the modeled PVA scenarios, the probability of extinction, mean time to extinction and minimum population size varied from zero to 100%, 63 years and 193 individuals, respectively. Habitat loss is the greatest threat to the conservation of Andean Condor populations in Ecuador. Population size reduction in scenarios that included habitat loss began within the first 15 years of this threat. Population reinforcement had no effects on the recovery of Andean Condor populations given the current status of the species in Ecuador. The population size estimate presented in this study is the lower than those reported previously in other countries where the species occur. The inferences derived from the population viability analysis have implications for Condor management in Ecuador. This study highlights the need to redirect efforts from captive breeding and population reinforcement to habitat conservation.

  14. Andean Condor (Vultur gryphus) in Ecuador: Geographic Distribution, Population Size and Extinction Risk.

    Science.gov (United States)

    Naveda-Rodríguez, Adrián; Vargas, Félix Hernán; Kohn, Sebastián; Zapata-Ríos, Galo

    2016-01-01

    The Andean Condor (Vultur gryphus) in Ecuador is classified as Critically Endangered. Before 2015, standardized and systematic estimates of geographic distribution, population size and structure were not available for this species, hampering the assessment of its current status and hindering the design and implementation of effective conservation actions. In this study, we performed the first quantitative assessment of geographic distribution, population size and population viability of Andean Condor in Ecuador. We used a methodological approach that included an ecological niche model to study geographic distribution, a simultaneous survey of 70 roosting sites to estimate population size and a population viability analysis (PVA) for the next 100 years. Geographic distribution in the form of extent of occurrence was 49 725 km2. During a two-day census, 93 Andean Condors were recorded and a population of 94 to 102 individuals was estimated. In this population, adult-to-immature ratio was 1:0.5. In the modeled PVA scenarios, the probability of extinction, mean time to extinction and minimum population size varied from zero to 100%, 63 years and 193 individuals, respectively. Habitat loss is the greatest threat to the conservation of Andean Condor populations in Ecuador. Population size reduction in scenarios that included habitat loss began within the first 15 years of this threat. Population reinforcement had no effects on the recovery of Andean Condor populations given the current status of the species in Ecuador. The population size estimate presented in this study is the lower than those reported previously in other countries where the species occur. The inferences derived from the population viability analysis have implications for Condor management in Ecuador. This study highlights the need to redirect efforts from captive breeding and population reinforcement to habitat conservation. PMID:26986004

  15. Shifts in leaf litter breakdown along a forest-pasture-urban gradient in Andean streams.

    Science.gov (United States)

    Iñiguez-Armijos, Carlos; Rausche, Sirkka; Cueva, Augusta; Sánchez-Rodríguez, Aminael; Espinosa, Carlos; Breuer, Lutz

    2016-07-01

    Tropical montane ecosystems of the Andes are critically threatened by a rapid land-use change which can potentially affect stream variables, aquatic communities, and ecosystem processes such as leaf litter breakdown. However, these effects have not been sufficiently investigated in the Andean region and at high altitude locations in general. Here, we studied the influence of land use (forest-pasture-urban) on stream physico-chemical variables (e.g., water temperature, nutrient concentration, and pH), aquatic communities (macroinvertebrates and aquatic fungi) and leaf litter breakdown rates in Andean streams (southern Ecuador), and how variation in those stream physico-chemical variables affect macroinvertebrates and fungi related to leaf litter breakdown. We found that pH, water temperature, and nutrient concentration increased along the land-use gradient. Macroinvertebrate communities were significantly different between land uses. Shredder richness and abundance were lower in pasture than forest sites and totally absent in urban sites, and fungal richness and biomass were higher in forest sites than in pasture and urban sites. Leaf litter breakdown rates became slower as riparian land use changed from natural to anthropogenically disturbed conditions and were largely determined by pH, water temperature, phosphate concentration, fungal activity, and single species of leaf-shredding invertebrates. Our findings provide evidence that leaf litter breakdown in Andean streams is sensitive to riparian land-use change, with urban streams being the most affected. In addition, this study highlights the role of fungal biomass and shredder species (Phylloicus; Trichoptera and Anchytarsus; Coleoptera) on leaf litter breakdown in Andean streams and the contribution of aquatic fungi in supporting this ecosystem process when shredders are absent or present low abundance in streams affected by urbanization. Finally, we summarize important implications in terms of managing of

  16. Chronic hypoxia in Andeans; are there lessons for neurology at sea level?

    Science.gov (United States)

    Appenzeller, Otto; Minko, Tamara; Qualls, Clifford; Pozharov, Vitaly; Gamboa, Jorge; Gamboa, Alfredo; Pakunlu, Rafica I

    2006-08-15

    Hypoxia is implicated in aging and neurodegenerative diseases. We posited that changes in gene expression induced by ambient hypoxia at altitude may be neuroprotective to natives of these regions. We studied 30 men. Twenty natives of Cerro de Pasco (CP), altitude 4,338 m were examined in CP; then transported within 6 h to Lima (150 m-sea level) and examined 1 h after arrival. They were assessed by a Chronic Mountain Sickness-score (CMS-sc) in CP, 10 were normal Andeans and 10 had chronic mountain sickness (CMS), a sudden inexplicable loss of adaptation to their native environment. RNA was extracted from venous blood white cells. The Andeans were compared to 10 normal US men living at 1500 m using RT-PCR. We focused on the cyto-neuro-protective genes, Ataxia telangiectasia mutated (ATM), heme-oxygenase-1 (HMOX 1), heat shock protein-70 (HSP-70), heat shock protein-90 (HSP-90), and the neuroprotective enzyme, nicotinamide mononucleotide adenylyl transferase 1 (Nnmat 1). CMS patients had significantly higher levels of gene expression (HMOX-1, HSP-70, ATM) than Andean controls in CP. HSP-90 and Nmnat 1, however, were higher in Andean controls in all locations. Significant reductions of all gene products, within an hour of arriving in normoxia in Lima, were found. In Andean controls, the gene products in Lima fell to levels approaching US controls. Correlation and regression methods showed men with high expression of all gene products had an average CMS-sc=19.8; those with low expression a normal score (9.4, P=0.02). ATM expression was related to age (P<0.001). The natural experiment that unfolds in the mountainous regions of the world provides opportunities to study neuroprotection in intact humans.

  17. Andean Condor (Vultur gryphus in Ecuador: Geographic Distribution, Population Size and Extinction Risk.

    Directory of Open Access Journals (Sweden)

    Adrián Naveda-Rodríguez

    Full Text Available The Andean Condor (Vultur gryphus in Ecuador is classified as Critically Endangered. Before 2015, standardized and systematic estimates of geographic distribution, population size and structure were not available for this species, hampering the assessment of its current status and hindering the design and implementation of effective conservation actions. In this study, we performed the first quantitative assessment of geographic distribution, population size and population viability of Andean Condor in Ecuador. We used a methodological approach that included an ecological niche model to study geographic distribution, a simultaneous survey of 70 roosting sites to estimate population size and a population viability analysis (PVA for the next 100 years. Geographic distribution in the form of extent of occurrence was 49 725 km2. During a two-day census, 93 Andean Condors were recorded and a population of 94 to 102 individuals was estimated. In this population, adult-to-immature ratio was 1:0.5. In the modeled PVA scenarios, the probability of extinction, mean time to extinction and minimum population size varied from zero to 100%, 63 years and 193 individuals, respectively. Habitat loss is the greatest threat to the conservation of Andean Condor populations in Ecuador. Population size reduction in scenarios that included habitat loss began within the first 15 years of this threat. Population reinforcement had no effects on the recovery of Andean Condor populations given the current status of the species in Ecuador. The population size estimate presented in this study is the lower than those reported previously in other countries where the species occur. The inferences derived from the population viability analysis have implications for Condor management in Ecuador. This study highlights the need to redirect efforts from captive breeding and population reinforcement to habitat conservation.

  18. Reconciling Local and Global Agendas in Sustainable Development: Participatory Research with Indigenous Andean Communities

    Institute of Scientific and Technical Information of China (English)

    Robert E. Rhoades; Virginia Nazarea

    2006-01-01

    This paper discusses participatory research in the Andes and presents a case study in Cotacachi, Ecuador, where sustainability scientists and indigenous people seek common ground in their respective but drastically different research and social agendas. Participatory research based on Andean experiences pre-dated and inspired much of the later international movement in agriculture, health, and conservation. Andean communities have a long history in demanding that outsiders address the needs of the community as a condition for carrying out scientific or applied activities. What an Andean community, however, sees as relevant may or may not practiced throughout much of the world. In fact,overzealous participatory researchers are just as bothersome as their predecessors bearing long questionnaires. More important to Andean people is an equitable relationship with researchers and developers in which exchanges of value are made. A research is drawn. In the case of the SANREM project in Cotacachi, Ecuador, scientists carried out enriching research activities of interest to local people as a way to generate social capital for conducting basic research which does not have an obvious, immediate local benefit. The requested research did not have a conventional participatory methodology but provided valuable products (educational opportunity,germplasm, community visualization tools, and information) to the indigenous community in exchange for time and resources to conduct research on more basic natural resource questions. We argue that in the Andean context the key to reconciling the needs of scientists and of local needs is seeking new forms of equitable collaboration which reach beyond the present and now somewhat tired discourse of ‘participation'.

  19. Andean Condor (Vultur gryphus) in Ecuador: Geographic Distribution, Population Size and Extinction Risk

    Science.gov (United States)

    Naveda-Rodríguez, Adrián; Vargas, Félix Hernán; Kohn, Sebastián; Zapata-Ríos, Galo

    2016-01-01

    The Andean Condor (Vultur gryphus) in Ecuador is classified as Critically Endangered. Before 2015, standardized and systematic estimates of geographic distribution, population size and structure were not available for this species, hampering the assessment of its current status and hindering the design and implementation of effective conservation actions. In this study, we performed the first quantitative assessment of geographic distribution, population size and population viability of Andean Condor in Ecuador. We used a methodological approach that included an ecological niche model to study geographic distribution, a simultaneous survey of 70 roosting sites to estimate population size and a population viability analysis (PVA) for the next 100 years. Geographic distribution in the form of extent of occurrence was 49 725 km2. During a two-day census, 93 Andean Condors were recorded and a population of 94 to 102 individuals was estimated. In this population, adult-to-immature ratio was 1:0.5. In the modeled PVA scenarios, the probability of extinction, mean time to extinction and minimum population size varied from zero to 100%, 63 years and 193 individuals, respectively. Habitat loss is the greatest threat to the conservation of Andean Condor populations in Ecuador. Population size reduction in scenarios that included habitat loss began within the first 15 years of this threat. Population reinforcement had no effects on the recovery of Andean Condor populations given the current status of the species in Ecuador. The population size estimate presented in this study is the lower than those reported previously in other countries where the species occur. The inferences derived from the population viability analysis have implications for Condor management in Ecuador. This study highlights the need to redirect efforts from captive breeding and population reinforcement to habitat conservation. PMID:26986004

  20. Four New Species of Nepenthes L. (Nepenthaceae from the Central Mountains of Mindanao, Philippines

    Directory of Open Access Journals (Sweden)

    Thomas Gronemeyer

    2014-06-01

    Full Text Available Together with the islands of Sumatra (Indonesia and Borneo (Indonesia, Malaysia, the Philippines are the main center of diversity for carnivorous pitcher plants of the genus, Nepenthes L. Nepenthes are the largest of all carnivorous plants, and the species with the biggest pitchers are capable of trapping and digesting small amphibians and even mammals. The central cordillera of Mindanao Island in the south of the Philippines is mostly covered with old, primary forest and is the largest remaining cohesive, untouched area of wilderness in the Philippines. In a recent field exploration of two areas of the central cordillera, namely Mount Sumagaya and a section of the Pantaron range, four new taxa of Nepenthes were discovered. These four remarkable new species, N. pantaronensis, N. cornuta, N. talaandig and N. amabilis, are described, illustrated and assessed.

  1. Four New Species of Nepenthes L. (Nepenthaceae) from the Central Mountains of Mindanao, Philippines.

    Science.gov (United States)

    Gronemeyer, Thomas; Coritico, Fulgent; Wistuba, Andreas; Marwinski, David; Gieray, Tobias; Micheler, Marius; Mey, François Sockhom; Amoroso, Victor

    2014-01-01

    Together with the islands of Sumatra (Indonesia) and Borneo (Indonesia, Malaysia), the Philippines are the main center of diversity for carnivorous pitcher plants of the genus, Nepenthes L. Nepenthes are the largest of all carnivorous plants, and the species with the biggest pitchers are capable of trapping and digesting small amphibians and even mammals. The central cordillera of Mindanao Island in the south of the Philippines is mostly covered with old, primary forest and is the largest remaining cohesive, untouched area of wilderness in the Philippines. In a recent field exploration of two areas of the central cordillera, namely Mount Sumagaya and a section of the Pantaron range, four new taxa of Nepenthes were discovered. These four remarkable new species, N. pantaronensis, N. cornuta, N. talaandig and N. amabilis, are described, illustrated and assessed. PMID:27135505

  2. Relating geodynamic setting to periods of crustal growth and reworking as illustrated by the Phanerozoic granitoids of the Eastern Cordillera of South Peru

    Science.gov (United States)

    Reitsma, M.; Schaltegger, U.; Spikings, R.; Ulianov, A.; Gerdes, A.; Chiaradia, M.

    2012-04-01

    The granitoids that form the backbone of the Eastern Cordillera of Peru between 12 and 14°S, are the ideal material for a case study to relate geodynamic setting to crustal growth over the period of a Wilson cycle. Extension related plutons were emplaced in the back-arc region of the Western Gondwana margin during the Ordovician, Permo-Carboniferous, Triassic and Early Jurassic. With the onset of the Andean cycle in the Middle Jurassic the South American margin was under compression, the plutonic record of this period is in the study area restricted to the Eocene and Miocene. The Ordovician to Triassic back-arc related plutons share many geochemical characteristics that point to dominant crustal reworking as the main process during their formation. These are 1) their mainly felsic and peraluminous nature; 2) the similarity of whole rock REE and trace element compositions compared to those of average continental crust; 3) the presence of negative Nb-Ta anomalies only in the more evolved samples which indicates that these excursions have been obtained by crustal melting rather than from a slab fluid and 4) the presence of significant amounts of xenocrystic cores in zircon. According to the literature the last major episode of juvenile crust formation was during the Grenvillian age Sunsas event (1.2 - 0.9 Ga) related to the collision of Laurentia and south-western Amazonia during the assembly of Rodinia. Hf-isotopes on zircons from the Ordovician, Permo-Carboniferous and Triassic plutons confirm their origin as mainly crustal melts generated by reworking of Sunsas-age crust. Under these geodynamic conditions it is mainly the crust that melts due to an elevated geothermal gradient as the result of crustal thinning. However, data from Jurassic nepheline bearing syenite and Eocene hornblende diorite and monzonite have epsilon Hfi values well above those of Sunsas crust, indicating an important mantle component in the melts. The Jurassic geodynamic setting is interpreted

  3. An Andean tectonic cycle:From crustal thickening to extension in a thin crust (34º-37ºSL)

    Institute of Scientific and Technical Information of China (English)

    Victor A. Ramos; Vanesa D. Litvak; Andrés Folguera; Mauro Spagnuolo

    2014-01-01

    Several orogenic cycles of mountain building and subsequent collapse associated with periods of shal-lowing and steepening of subduction zones have been recognized in recent years in the Andes. Most of them are characterized by widespread crustal delamination expressed by large calderas and rhyolitic flare-up produced by the injection of hot asthenosphere in the subduction wedge. These processes are related to the increase of the subduction angle during trench roll-back. The Payenia paleoflat-slab, in the southern Central Andes of Argentina and Chile (34º~37º S) recorded a complete cycle from crustal thickening and mountain uplift to extensional collapse and normal faulting, which are related to changes in the subduction geometry. The early stages are associated with magmatic expansion and migration, subsequent deformation and broken foreland. New ages and geochemical data show the middle to late Miocene expansion and migration of arc volcanism towards the foreland region was associated with important deformation in the Andean foothills. However, the main difference of this orogenic cycle with the previously described cycles is that the steepening of the oceanic subducted slab is linked to basaltic flooding of large areas in the retroarc under an extensional setting. Crustal delamination is concentrated only in a narrow central belt along the cordilleran axis. The striking differences between the two types of cycles are interpreted to be related to the crustal thickness when steepening the subducting slab. The crustal thickness of the Altiplano is over 60e80 km, whereas Payenia is less than 42 km in the axial part, and near 30 km in the retroarc foothills. The final extensional regime associated with the slab steepening favors the basaltic flooding of more than 8400 km3 in an area larger than 40,000 km2, through 800 central vents and large fissures. These characteristics are unique in the entire present-day Andes.

  4. CO2-rich thermomineral groundwater in the Betic Cordilleras, southeastern Spain: Genesis and tectonic implications

    Science.gov (United States)

    Cerón, J. C.; Martín-Vallejo, M.; García-Rossell, L.

    The CO2-rich thermal groundwater in the Betic Cordilleras in Spain has been studied with regard to the geological and hydrogeological setting, physical and chemical characteristics, and 13C-isotope content. The study area is about 60km northeast of Almería city, in southeastern Spain. The thermomineral waters are plentiful and are related to regional geothermal anomalies. Temperatures of 20 -41°C, high bicarbonate concentrations (183-1824mg/L), and high amounts of PCO2 (Resumen Las aguas termales con elevados contenidos en CO2 de las Cordilleras Béticas han sido estudiadas en relación con los aspectos geológicos e hidrogeológicos, sus características físicas y químicas, y sus contenidos en 13C. El área de estudio se encuentra aproximadamente a 60km al noreste de la ciudad de Almería, en el sureste de España. Las aguas termominerales son numerosas y están relacionadas con anomalías geotermales regionales. El agua subterránea tiene una temperatura comprendida entre 20-41°C, alta concentración de bicarbonatos (entre 183-1824mg/L) y elevada PCO2 (<1.1bares). Las variaciones espaciales de CO2 están relacionadas con la proximidad de los sistemas de fallas de Carboneras, Palomares y Guadalentín, y puede ser la manifestación en superficie de una zona de adelgazamiento cortical. Los datos de δ13C indican un posible aporte de origen profundo de CO2, posiblemente del manto y/o de las rocas carbonatadas presentes en el sustrato metamórfico. Las elevadas concentraciones de CO2 en el agua subterránea origina problemas en los sondeos y en el uso del agua. El carácter hidrotermal de este área estaría relacionado con su actividad neotectónica.

  5. Downscaling reanalysis data to high-resolution variables above a glacier surface (Cordillera Blanca, Peru)

    Science.gov (United States)

    Hofer, Marlis; Mölg, Thomas; Marzeion, Ben; Kaser, Georg

    2010-05-01

    Recently initiated observation networks in the Cordillera Blanca provide temporally high-resolution, yet short-term atmospheric data. The aim of this study is to extend the existing time series into the past. We present an empirical-statistical downscaling (ESD) model that links 6-hourly NCEP/NCAR reanalysis data to the local target variables, measured at the tropical glacier Artesonraju (Northern Cordillera Blanca). The approach is particular in the context of ESD for two reasons. First, the observational time series for model calibration are short (only about two years). Second, unlike most ESD studies in climate research, we focus on variables at a high temporal resolution (i.e., six-hourly values). Our target variables are two important drivers in the surface energy balance of tropical glaciers; air temperature and specific humidity. The selection of predictor fields from the reanalysis data is based on regression analyses and climatologic considerations. The ESD modelling procedure includes combined empirical orthogonal function and multiple regression analyses. Principal component screening is based on cross-validation using the Akaike Information Criterion as model selection criterion. Double cross-validation is applied for model evaluation. Potential autocorrelation in the time series is considered by defining the block length in the resampling procedure. Apart from the selection of predictor fields, the modelling procedure is automated and does not include subjective choices. We assess the ESD model sensitivity to the predictor choice by using both single- and mixed-field predictors of the variables air temperature (1000 hPa), specific humidity (1000 hPa), and zonal wind speed (500 hPa). The chosen downscaling domain ranges from 80 to 50 degrees west and from 0 to 20 degrees south. Statistical transfer functions are derived individually for different months and times of day (month/hour-models). The forecast skill of the month/hour-models largely depends on

  6. Past peak water in Peru's Cordillera Blanca: diagnosing the demise of glacier influence on stream discharge

    Science.gov (United States)

    Baraer, M.; Mark, B. G.; McKenzie, J. M.

    2011-12-01

    In conditions of continuous retreat, glaciers generate a temporary increase in stream runoff as they lose mass. Yet as the extant glacier volume diminishes, the annual runoff reaches a peak and is followed by a persistent decrease. In the present study we explore historical and modern discharge measurements measured between 1952 and 2010 at nine stations across the upper Rio Santa watershed, the basin that drains most of the western Cordillera Blanca, Peru, and situate the regional stream hydrology within this glacier influence change sequence. The relation between glacial retreat and stream discharge is investigated by the use of a simple water balance model that simulates glacier retreat influence on the annual and dry-season discharge, as well as on the annual discharge variability, permitting distinction between four phases of glacier retreat hydrological impact. The link between the modeled synthetic time series and the Cordillera Blanca discharge records is assessed using polynomial regressions and the Mann-Kendall non-parametric statistical test on daily discharge series for three hydrograph parameters: the yearly average, the dry season discharge and the variability coefficient. The glacial retreat for the same period is estimated using existing historical data of glacial coverage from an analysis of composite ASTER imagery that shows accelerating glacier recession in the upper Rio Santa watershed, with the overall glacierized area decreasing annually by 0.81 % between 1990 and 2009. The results provide statistically significant evidence that seven of the nine discharge time series have crossed a critical transition, and now exhibit a decreasing trend related to glacier retreat. La Balsa station measures discharge from the entire upper Rio Santa before entering a major hydro-electrical power plant, and it is undergoing a decline in dry season flow that probably began during the 1970s. Our results predict that if the glaciers completely melt, stream

  7. The Genetic History of Peruvian Quechua-Lamistas and Chankas: Uniparental DNA Patterns among Autochthonous Amazonian and Andean Populations.

    Science.gov (United States)

    Sandoval, José R; Lacerda, Daniela R; Acosta, Oscar; Jota, Marilza S; Robles-Ruiz, Paulo; Salazar-Granara, Alberto; Vieira, Pedro Paulo R; Paz-Y-Miño, César; Fujita, Ricardo; Santos, Fabricio R

    2016-03-01

    This study focuses on the genetic history of the Quechua-Lamistas, inhabitants of the Lamas Province in the San Martin Department, Peru, who speak their own distinct variety of the Quechua family of languages. It has been suggested that different pre-Columbian ethnic groups from the Peruvian Amazonia, like the Motilones or "shaven heads", assimilated the Quechua language and then formed the current native population of Lamas. However, many Quechua-Lamistas claim to be direct descendants of the Chankas, a famous pre-Columbian indigenous group that escaped from Inca rule in the Andes. To investigate the Quechua-Lamistas and Chankas' ancestries, we compared uniparental genetic profiles (17 STRs of Q-M3 Y-chromosome and mtDNA complete control region haplotypes) among autochthonous Amazonian and Andean populations from Peru, Bolivia and Ecuador. The phylogeographic and population genetic analyses indicate a fairly heterogeneous ancestry for the Quechua-Lamistas, while they are closely related to their neighbours who speak Amazonian languages, presenting no direct relationships with populations from the region where the ancient Chankas lived. On the other hand, the genetic profiles of self-identified Chanka descendants living in Andahuaylas (located in the Apurimac Department, Peru, in the Central Andes) were closely related to those living in Huancavelica and the assumed Chanka Confederation area before the Inca expansion. PMID:26879156

  8. Four New Species of Nepenthes L. (Nepenthaceae) from the Central Mountains of Mindanao, Philippines

    OpenAIRE

    Thomas Gronemeyer; Fulgent Coritico; Andreas Wistuba; David Marwinski; Tobias Gieray; Marius Micheler; François Sockhom Mey; Victor Amoroso

    2014-01-01

    Together with the islands of Sumatra (Indonesia) and Borneo (Indonesia, Malaysia), the Philippines are the main center of diversity for carnivorous pitcher plants of the genus, Nepenthes L. Nepenthes are the largest of all carnivorous plants, and the species with the biggest pitchers are capable of trapping and digesting small amphibians and even mammals. The central cordillera of Mindanao Island in the south of the Philippines is mostly covered with old, primary forest and is the largest rem...

  9. Estructura y riqueza de plantas arborescentes en Un Bosque de Niebla de la Cordillera Central (Tolima, Colombia

    Directory of Open Access Journals (Sweden)

    Campo Kurmen Juan Manuel

    2006-06-01

    Full Text Available Se presenta el estudio de la estructura, la riqueza y la composición florística del componente arborescente de un
    bosque entresacado, en la vereda Dantas, municipio de Ibagué, Tolima, Colombia, con base en el mues-treo de
    los individuos con DAP 2,5 cm en 0,1 ha. El bosque se caracteriza por la escasez de lianas y de hemiepífitas,
    ausencia de familias típicas de bosques de niebla colombianos entre los 2.000 y 2.500 msnm (Araceae, Ericaceae,
    Myrtaceae, Meliaceae y Aquifoliaceae y por un incremento en la riqueza de familias como Sabiaceae y Euphorbiaceae.
    Comparado con otros bosques de niebla de los Andes colombianos y del neotrópico, éste presenta una de las
    más bajas densidades de tallos (237 individuos con DAP ³ 2,5 cm por 0,1 ha y una proporción de árboles grandes
    muy alta (39,7% individuos con DAP 10 cm por 0,1 ha. Aparentemente, los efectos de la extracción selectiva
    de maderas sobre la riqueza, la estructura y la composición, son la disminución de la densidad y la riqueza de lianas, mayor riqueza de Sabiaceae y Euphorbiaceae y mayor densidad de especies secundarias como Hedyosmum goudotianum Slms-Laubach var. goudatianum, Miconia resima Naud. y Palicourea calophlebia Standl.

  10. 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...

  11. Integrative taxonomy and conservation status of amphibians in western Panama with an emphasis on the highlands of the Cordillera Central

    OpenAIRE

    Hertz, Andreas

    2015-01-01

    Amphibien bevölkern die Erde seit über 300 Millionen Jahren und sind heute, mit über 7000 bekannten Arten und vielen weiteren die noch zu entdecken sind, eine der artenreichsten Wirbeltierklassen der Welt. Wie verschiedene Studien herausgefunden haben ist etwa ein Drittel der bekannten Amphibienarten unmittelbar vom Aussterben bedroht, was sie zur meist bedrohten Wirbeltierklasse macht. Panama hat im Verhältnis zu seiner relativ kleinen Landesfläche eine der artenreichsten Amphibienfaunen wel...

  12. Regional Trade Agreements: Effects of the Andean and Mercosur Packs on the Venezuelan Soybean Trade and U.S. Exports

    OpenAIRE

    Reeder, John; Torene, Jillian A.; Jabara, Cathy L.; Babula, Ronald A.

    2005-01-01

    Since the mid-1990s, the two regional trade agreements in South America, the southern Mercosur Pact (among Brazil, Argentina, Paraguay and Uruguay), and the northern Andean Pact (among Venezuela, Colombia, Ecuador, Bolivia, and Peru) noticeably affected certain trade patterns between the two pacts' members and with the United States for various reasons discussed herein. The effect of trade diversion owing to the Andean Pact with its common external tariff and price band system against non-And...

  13. Sedimentary cyclicity in early Pleistocene, evaporitic, playa-lake lacustrine deposits in the Guadix-Baza basin (Betic Cordillera, Spain); Ciclicidad sedimentaria en depositos lacustres evaporiticos tipo playa-lake del Pleistoceno inferior en la cuenca de Guadix-Baza (Cordillera Betica, Espana)

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Aguilar, J. M.; Guera-Menchan, A.; Serrano, F.; Palmqvist, P.

    2013-06-01

    The Guadix-Baza basin (Betic Cordillera, southern Spain) contains in its eastern sector an early Pleistocene (Gelasian and lowermost Calabrian) sedimentary unit that was deposited in a shallow lacustrine environment. Given that the chronological limits of this unit lie between 2.5 and 1.6 Ma BP, the thickness of its preserved sediments (400 m) and high sedimentation rate (44.4 cm/ka) are remarkable. Numerous sedimentary cycles marked by an alternation of marls and sands are commonly found in the marginal sectors and marls and gypsum in the central sector, which would owe their origins to permanent flooding and evaporation/ re-flooding phases due to global climatic changes. Spectral analyses carried out using Fourier transform have revealed the existence of temporary frequencies associated with sedimentary cycles of between 0.2 and 5.2 ka. The origin of these cycles may be associated with variations in solar radiation and oscillations in the Moons orbital position, which would induce global climatic changes resulting in the rise and fall of the water table of the lake. Autocorrelation analyses conducted separately on the marly and evaporitic levels support this conclusion, as they indicate the existence of significant direct correlations between about 4 to 12 sedimentary cycles, which would correspond to repetitions of the stratigraphic series over a time span of 1.3 to 4 ka. (Author)

  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. Potentially synbiotic product based on Andean blackberry (Rubus glaucus by applying vacuum impregnation

    Directory of Open Access Journals (Sweden)

    Rodríguez-Barona, Sneyder

    2012-12-01

    Full Text Available The aim of this study was to develop a product potentially symbiotic by applying vacuum impregnating over Andean blackberry slices immersed in three solutions: a solution of fructooligosaccharides (FOS, natural blackberry juice, and a mixture of fruit juice and solution of FOS, inoculated with Lactobacillus casei ATCC 393 with 109 UCF/mL. The blackberry slices impregnated with the mixture of fruit juice and FOS, and with just the FOS solution, they were found to contain 108 UCF/g and over 0.0022 g of FOS per 100g of impregnated sample after being stored for 72 hours under refrigeration conditions. The results indicate that the presence of FOS in the impregnation solution increases the viability of the microorganisms and it can be concluded that it is feasible to obtain a potentially symbiotic food from Andean blackberry by means of the impregnation of its porous matrix with beneficial microorganisms and prebiotic substances.

  16. Diversity and ecological ranges of plant species from dry inter-Andean valleys

    DEFF Research Database (Denmark)

    Quintana, Catalina

    of Ecuadorian dry inter-Andean valleys vegetation, including information related to the physical settings as well as to the vegetation and flora of the valleys. 2) This chapter unveils the influence of disturbance, water availability and low temperature in shaping species composition and occurrence. We found...... found on steep slopes and in ravines. These areas of original dry valley vegetation preserve many wild relatives of cultivated plants on the one hand and old lineages of other wild plant groups. Dry inter-Andean valleys (DIAVs) in Ecuador therefore makeup a biodiversity hot spot for both plants...... contribute to biodiversity conservation. The studies presented here demonstrates the importance of these valleys and also shows that they can be used for testing hypothesis related to species distribution, migration and conservation. If DIAVs biodiversity is preserved the maintenance of ecosystem services...

  17. Projected distribution shifts and protected area coverage of range-restricted Andean birds under climate change

    OpenAIRE

    Verónica del Rosario Avalos; Jaime Hernández

    2015-01-01

    In this study we projected the effect of anthropogenic climate change in endemic and restricted-range Andean bird species that spread out from the center of Bolivia to southeastern Peru. We also analyzed the representation of these species in protected areas. The ensemble forecasts from niche-based models indicated that 91–100% of species may reduce their range size under full and no dispersal scenarios, including five species that are currently threatened. The large range reduction (average ...

  18. Three-dimensional density model of the Nazca plate and the Andean continental margin

    Science.gov (United States)

    Tassara, AndréS.; GöTze, Hans-Jürgen; Schmidt, Sabine; Hackney, Ron

    2006-09-01

    We forward modeled the Bouguer anomaly in a region encompassing the Pacific Ocean (85°W) and the Andean margin (60°W) between northern Peru (5°S) and Patagonia (45°S). The three-dimensional density model that reproduces the gravity field is a continental-scale representation of density structure to 410 km depth that characterizes the mantle and crust of the oceanic Nazca plate, subducted slab and continental margin with a minimum number of bodies. We predefined the density of each body after studying the dependency of density on composition of crustal and mantle materials and pressure-temperature conditions appropriate for the Andean setting. A database of independent geophysical information constrains the geometry of the top of the subducted slab, locally the Moho of the oceanic and continental crusts and, indirectly, the lithosphere-asthenosphere boundary underneath the continental plate. Other boundaries, notably the intracrustal density discontinuity separating upper from lower crust below the continent, were not constrained and their geometry is the result of fitting the observed and calculated Bouguer anomaly during forward modeling. This contribution presents the model to the Andean geoscientific community and contains some tools, like a sensitivity analysis, that helps potential users of the model to interpret its results. We describe and discuss some of these results in order to illustrate the application of the model to the study of a wide range of phenomena (e.g., modification of oceanic plate structure by hot spots, shape of the subducted slab, thermal structure of the continental lithosphere, compensation mechanism and formation of orogenic relieve, causes of Andean segmentation).

  19. Large Differences in Bacterial Community Composition among Three Nearby Extreme Waterbodies of the High Andean Plateau.

    Science.gov (United States)

    Aguilar, Pablo; Acosta, Eduardo; Dorador, Cristina; Sommaruga, Ruben

    2016-01-01

    The high Andean plateau or Altiplano contains different waterbodies that are subjected to extreme fluctuations in abiotic conditions on a daily and an annual scale. The bacterial diversity and community composition of those shallow waterbodies is largely unexplored, particularly, of the ponds embedded within the peatland landscape (i.e., Bofedales). Here we compare the small-scale spatial variability (Altiplano peatland ponds represent a hitherto unknown source of microbial diversity.

  20. Developing tools to evaluate the environmental status of Andean basins with mining activities

    OpenAIRE

    Yacoub López, Cristina

    2013-01-01

    The water quality status of an Andean river basin was characterised and the pressures from anthropogenic activities were evaluated to enhance the available knowledge of the environment within an ecosystem in Peru. This investigation was conducted to assess the environmental status of the basin as a first step to introducing river management plans and specific water quality programmes. A continuous simulation model and an environmental monitoring program were developed, taking into account the...

  1. Explaining Andean Potato Weevils in Relation to Local and Landscape Features: A Facilitated Ecoinformatics Approach

    OpenAIRE

    Parsa, Soroush; Ccanto, Raúl; Olivera, Edgar; Scurrah, María; Alcázar, Jesús; Rosenheim, Jay A.

    2012-01-01

    Background Pest impact on an agricultural field is jointly influenced by local and landscape features. Rarely, however, are these features studied together. The present study applies a “facilitated ecoinformatics” approach to jointly screen many local and landscape features of suspected importance to Andean potato weevils (Premnotrypes spp.), the most serious pests of potatoes in the high Andes. Methodology/Principal Findings We generated a comprehensive list of predictors of weevil damage, i...

  2. Child Malnutrition, Social Development and Health Services in the Andean Region

    OpenAIRE

    LARREA CARLOS; MONTALVO PEDRO; RICAURTE ANA

    2005-01-01

    This study analyzes social, ethnic and regional determinants of child malnutrition, as well as the effects of access to health services in the Andean Region, through a comparison between Ecuador, Peru and Bolivia. These three countries share a profile with high stunting prevalence and strong socio-economic, regional and ethnic disparities. The analysis is conducted using DHS (Peru 1992, 1996 and 2000, Bolivia 1997) and LSMS (Ecuador 1998) surveys and it focuses on an international comparative...

  3. THE ROLE OF COLLECTIVE IDENTITY AND REGIONAL INSTITUTIONS IN THE ANDEAN COMMUNITY

    OpenAIRE

    Prieto Corredor, German Camilo

    2013-01-01

    This thesis analyses the terms in which collective identity and regional institutions can explain state action towards the unfolding of regionalism in the Andean Community (AC). This analysis develops a constructivist approach that assesses constitutive and casual effects of ideas in order to provide explanations. For the assessment and distinction of these effects, the thesis proposes an interpretive method that consists of focusing on transitive verbs and metaphors denoting causation that s...

  4. The Corregidores of the Colca Valley, Peru: Imperial Administration in an Andean Region

    OpenAIRE

    Cook, Noble David

    2003-01-01

    The corregidor de los indios was introduced into the Viceroyalty of Peru by Governor García de Castro in 1565. The institution was designed to limit the power of the encomendero elite and to improve administration and justice in the Andean countryside. Here we examine the impact of the reforms at the local level, the corregimiento of Los Collaguas in the Colca Valley, located between Cuzco and Arequipa. Althought the Crown was largely successful in weakening the encomienda, possibility of gra...

  5. Transplanting the European Court of Justice: The Experience of the Andean Tribunal of Justice

    OpenAIRE

    Osvaldo Saldías; Laurence R. Helfer; Alter, Karen J.

    2011-01-01

    Although there is an extensive literature on domestic legal transplants, far less is known about the transplantation of supranational judicial bodies. The Andean Tribunal of Justice (ATJ) is one of eleven copies of the European Court of Justice (ECJ), and the third most active international court. This article considers the origins and evolution of the ATJ as a transplanted judicial institution. It first reviews the literatures on legal transplants, neofunctionalist theory, and the spread of ...

  6. Proliferation of Hydroelectric Dams in the Andean Amazon and Implications for Andes-Amazon Connectivity

    Science.gov (United States)

    Finer, Matt; Jenkins, Clinton N.

    2012-01-01

    Due to rising energy demands and abundant untapped potential, hydropower projects are rapidly increasing in the Neotropics. This is especially true in the wet and rugged Andean Amazon, where regional governments are prioritizing new hydroelectric dams as the centerpiece of long-term energy plans. However, the current planning for hydropower lacks adequate regional and basin-scale assessment of potential ecological impacts. This lack of strategic planning is particularly problematic given the intimate link between the Andes and Amazonian flood plain, together one of the most species rich zones on Earth. We examined the potential ecological impacts, in terms of river connectivity and forest loss, of the planned proliferation of hydroelectric dams across all Andean tributaries of the Amazon River. Considering data on the full portfolios of existing and planned dams, along with data on roads and transmission line systems, we developed a new conceptual framework to estimate the relative impacts of all planned dams. There are plans for 151 new dams greater than 2 MW over the next 20 years, more than a 300% increase. These dams would include five of the six major Andean tributaries of the Amazon. Our ecological impact analysis classified 47% of the potential new dams as high impact and just 19% as low impact. Sixty percent of the dams would cause the first major break in connectivity between protected Andean headwaters and the lowland Amazon. More than 80% would drive deforestation due to new roads, transmission lines, or inundation. We conclude with a discussion of three major policy implications of these findings. 1) There is a critical need for further strategic regional and basin scale evaluation of dams. 2) There is an urgent need for a strategic plan to maintain Andes-Amazon connectivity. 3) Reconsideration of hydropower as a low-impact energy source in the Neotropics. PMID:22529979

  7. Proliferation of hydroelectric dams in the Andean Amazon and implications for Andes-Amazon connectivity.

    Directory of Open Access Journals (Sweden)

    Matt Finer

    Full Text Available Due to rising energy demands and abundant untapped potential, hydropower projects are rapidly increasing in the Neotropics. This is especially true in the wet and rugged Andean Amazon, where regional governments are prioritizing new hydroelectric dams as the centerpiece of long-term energy plans. However, the current planning for hydropower lacks adequate regional and basin-scale assessment of potential ecological impacts. This lack of strategic planning is particularly problematic given the intimate link between the Andes and Amazonian flood plain, together one of the most species rich zones on Earth. We examined the potential ecological impacts, in terms of river connectivity and forest loss, of the planned proliferation of hydroelectric dams across all Andean tributaries of the Amazon River. Considering data on the full portfolios of existing and planned dams, along with data on roads and transmission line systems, we developed a new conceptual framework to estimate the relative impacts of all planned dams. There are plans for 151 new dams greater than 2 MW over the next 20 years, more than a 300% increase. These dams would include five of the six major Andean tributaries of the Amazon. Our ecological impact analysis classified 47% of the potential new dams as high impact and just 19% as low impact. Sixty percent of the dams would cause the first major break in connectivity between protected Andean headwaters and the lowland Amazon. More than 80% would drive deforestation due to new roads, transmission lines, or inundation. We conclude with a discussion of three major policy implications of these findings. 1 There is a critical need for further strategic regional and basin scale evaluation of dams. 2 There is an urgent need for a strategic plan to maintain Andes-Amazon connectivity. 3 Reconsideration of hydropower as a low-impact energy source in the Neotropics.

  8. Coca: The History and Medical Significance of an Ancient Andean Tradition

    Directory of Open Access Journals (Sweden)

    Amy Sue Biondich

    2016-01-01

    Full Text Available Coca leaf products are an integral part of the lives of the Andean peoples from both a cultural and traditional medicine perspective. Coca is also the whole plant from which cocaine is derived. Coca products are thought to be a panacea for health troubles in regions of South America. This review will examine the toxicology of whole coca and will also look at medicinal applications of this plant, past, present, and future.

  9. Trench-parallel flow and seismic anisotropy in the Mariana and Andean subduction systems.

    Science.gov (United States)

    Kneller, Erik A; van Keken, Peter E

    2007-12-20

    Shear-wave splitting measurements above the mantle wedge of the Mariana and southern Andean subduction zones show trench-parallel seismically fast directions close to the trench and abrupt rotations to trench-perpendicular anisotropy in the back arc. These patterns of seismic anisotropy may be caused by three-dimensional flow associated with along-strike variations in slab geometry. The Mariana and Andean subduction systems are associated with the largest along-strike variations of slab geometry observed on Earth and are ideal for testing the link between slab geometry and solid-state creep processes in the mantle. Here we show, with fully three-dimensional non-newtonian subduction zone models, that the strong curvature of the Mariana slab and the transition to shallow slab dip in the Southern Andes give rise to strong trench-parallel stretching in the warm-arc and warm-back-arc mantle and to abrupt rotations in stretching directions that are accompanied by strong trench-parallel stretching. These models show that the patterns of shear-wave splitting observed in the Mariana and southern Andean systems may be caused by significant three-dimensional flow induced by along-strike variations in slab geometry. PMID:18097407

  10. Transplanting the European Court of Justice: The Experience of the Andean Tribunal of Justice

    Directory of Open Access Journals (Sweden)

    Osvaldo Saldías

    2011-05-01

    Full Text Available Although there is an extensive literature on domestic legal transplants, far less is known about the transplantation of supranational judicial bodies. The Andean Tribunal of Justice (ATJ is one of eleven copies of the European Court of Justice (ECJ, and the third most active international court. This article considers the origins and evolution of the ATJ as a transplanted judicial institution. It first reviews the literatures on legal transplants, neofunctionalist theory, and the spread of European ideas and institutions, explaining how the intersection of these literatures informs the study of supranational judicial transplants. The article next explains why the Andean Pact's member states decided to add a court to their regional integration initiative, why they adapted the European Community model, and how the ECJ's existence has shaped the evolution of Andean legal doctrine and the political space within which the ATJ operates. We conclude by analyzing how the ATJ's experience informs the challenges of supranational transplants and theories of supranational legal integration more generally. DOWNLOAD THIS PAPER FROM SSRN: http://ssrn.com/abstract=1948405

  11. A regional perspective on the diversity and conservation of tropical Andean fishes.

    Science.gov (United States)

    Anderson, Elizabeth P; Maldonado-Ocampo, Javier A

    2011-02-01

    The tropical Andes harbor an extraordinarily varied concentration of species in a landscape under increasing pressure from human activities. Conservation of the region's native plants and animals has received considerable international attention, but the focus has been on terrestrial biota. The conservation of freshwater fauna, particularly the conservation of fishes, has not been emphasized. Tropical Andean fishes are among the most understudied vertebrates in the world. We estimate that between 400 and 600 fish species inhabit the diverse aquatic environments in the region. Nearly 40% of these species are endemic. Tropical Andean fishes are vulnerable to ongoing environmental changes related to deforestation, water withdrawals, water pollution, species introductions, and hydropower development. Additionally, their distributions and population dynamics may be affected by hydrologic alterations and warmer water temperatures associated with projected climate change. Presently, at least three species are considered extinct, some populations are endangered, and some species are likely to decline or disappear. The long-term persistence of tropical Andean fishes will depend on greater consideration of freshwater systems in regional conservation initiatives.

  12. Clasificación de yeso mediante imágenes ASTER en la Cordillera Principal Mendocina Gypsum classification based on ASTER images in the Principal Cordillera of Mendoza

    OpenAIRE

    José F Mescua

    2010-01-01

    Se presenta una metodología para obtener el mapa de distribución de yeso con imágenes satelitales ASTER. Se utilizaron imágenes con nivel de procesamiento ASTERL3A correspondientes a dos áreas de la Cordillera Principal mendocina. La estratigrafía de las áreas de estudio se encuentra compuesta por una espesa sucesión sedimentaria mesozoica, volcanitas cenozoicas y depósitos cuaternarios. Dentro de los depósitos mesozoicos se encuentra la Formación Auquilco, integrada por yeso y anhidrita. El ...

  13. Dinámica e implicancia del aluvión de la laguna 513, Cordillera Blanca, Ancash, Perú Dinamics and implications of the laguna 513 Aluvion, Cordillera Blanca, Ancash Perú

    Directory of Open Access Journals (Sweden)

    Patricio Valderrama

    2012-09-01

    Full Text Available La Cordillera Blanca, al norte de Perú, es la zona con más actividad geodinámica externa en Perú. En ella ocurrieron grandes flujos de detritos de origen glaciar, varios de ellos fueron grandes desastres y cobraron miles de vidas. El 11 de abril del 2010, la laguna 513, ubicada en el centro de la Cordillera Blanca, sufrió un desembalse parcial por la caída de un gran bloque de hielo y rocas del nevado Hualcán (5500 m.s.n.m.. Este evento pese a ser de dimensiones considerables, no generó grandes pérdidas ni afectó alguna ciudad importante. Mediante simulaciones numéricas de flujo se estudió su dinámica, se determinó sus volúmenes y su turbulencia así como también explicamos e papel de la morfología de la zona en la desaceleración del flujo, su encausamiento en un valle fluvial y su posterior comportamiento como crecida de río. Las simulaciones realizadas mediante FLO2D se validan mediante comparaciones con imágenes de satélite post evento y datos de campo.The Cordillera Blanca in northern Peru is the most external geodynamics active areas in Perú. There have been occurred the biggest glacier source debris flow in the Peruvian history, most of them became on major disasters and claimed thousands of lives. On April 11th, 2010, the Laguna 513, located in the center of the Cordillera Blanca, suffered a partial GLOF due a massive rock and ice fall from Nevado Hualcán (5500 masl. This event, despite being of considerable size, did not generate large losses or affect any major city. Using numerical simulations we study the dynamics of the consequent GLOF and debris flow. We determined the volume and turbulence as well as also explained the role of the geomorphology of the area in the flow deceleration process and the river flood subsequent behavior. The FLO 2D simulations are validated with post event satellite image and field data.

  14. Temperaturas de formación en cataclasitas triásicas de la Cordillera Domeyko, Antofagasta, Chile Temperatures of formation in Triassic cataclasites of Cordillera Domeyko, Antofagasta, Chile

    OpenAIRE

    Hans Niemeyer; Héctor Berríos; María Dolores Ruiz Cruz

    2004-01-01

    Las cataclasitas, aquí estudiadas, representan antiguas zonas de falla exhumadas que afectan a macizos de rocas paleozoicas de la Cordillera Domeyko, conformando franjas largas, angostas y anastomosadas de orientación noroeste. Tanto las relaciones de contacto como dataciones radiométricas K-Ar (roca total), indican que la cataclasis se produjo durante el Triásico. Ésta se atribuye a una tectónica de 'rifts' intracontinentales ocurrida durante esa época en el borde suroccidental de Gondwana. ...

  15. Slope deformations in high-mountain regions as observed by InSAR: Examples from the Cordillera Blanca, Peru

    Science.gov (United States)

    Frey, Holger; Strozzi, Tazio; Caduff, Rafael; Huggel, Christian; Klimeš, Jan; Vilímek, Vít; Wiesmann, Andreas; Kääb, Andreas; Cochachin, Alejo; Plummer, Stephen

    2016-04-01

    Steep topography, the world's highest concentration of tropical glaciers, numerous glacial lakes and strong seismic activity combined with a densely populated valley bottom in the Rio Santa basin characterize the Cordillera Blanca in Peru. Besides glacier-related processes, a variety of landslide types and processes is present outside the glaciated areas, favoured by the steep terrain, geological conditions, sparse vegetation, intense precipitation, and strong seismicity. This combination of high hazard potentials and vulnerabilities results in a long list of natural disasters. Information on surface displacements is very valuable for early detection of emerging hazard potentials and their assessment. Interferometric processing of SAR data (InSAR) provides the possibility to remotely detect different types of surface displacement processes, also in remote locations where no other monitoring data are available. This contribution, developed under the ESA-funded S:GLA:MO project (sglamo.gamma-rs.ch), shows the potential of InSAR products for hazard assessments and glaciological investigations in high-mountain regions. We present a selection of different surface displacements as observed in the Cordillera Blanca based on InSAR data: a landslide zone near the Rampac Grande village, where in 2009 a landslide caused casualties and property loss; a landslide at the entry of the Santa Cruz Valley, northern Cordillera Blanca, where the displacement history could be reconstructed over five years; surface displacements at the interior moraine slopes surrounding Laguna Palcacocha, a major glacier lake above the city of Huaraz, which are compared to and complemented by geophysical investigations in the field; surface displacements at the moraine damming Laguna Safuna Alta, a glacier lake in the northern part of the Cordillera Blanca; glacier velocities across the entire Cordillera Blanca, revealing ice flow velocities of more than 200 m yr-1 at certain locations at the end of

  16. Structure of Sierra Blanca (Alpujarride Complex, west of the Betic Cordillera

    Directory of Open Access Journals (Sweden)

    Andreo, B.

    1995-04-01

    Full Text Available Sierra Blanca, situated in the SW of Málaga, forms part of the Blanca unit, belonging to the Alpujarride Complex of the Betic Cordillera. Its lithologic sequences are made up of a group of migmatites, gneisses and schists and an upper formation of marbles (white dolomitic and the bottom and blue calcareous towards the top, linked with a transitional contact. The structure of Sierra Blanca is comprised of folds, generally isoclinal, with reversed limbs and with important tectonic transpositions, the direction of which is approximately E-W in the eastern area and N-S and E-W in the West. In both areas the folds present opposing vergences, consistently towards the interior of the sierra. The origin of these structures is explained with a model of westerly movements of the Blanca unit, in relation to the Los Reales unit, with the formation of frontal and lateral folds. In its advancement, the western part of Sierra Blanca underwent an important anti-clockwise rotation responsible for the co-existence of folds in N-S and E-W directions. These structures occurred under ductile conditions, owing to the presence of important overthrusting peridotitic masses of the Los Reales unit. This model of westerly displacement is inserted in the process undergone by the Betic-Rif Internal Zones (with Blanca and Los Reales units included which occurred at the end of the Oligocene-Early Miocene when the Gibraltar arch began to be formed.Sierra Blanca, situada al SW de Málaga, forma parte de la unidad de Blanca que pertenece al complejo Alpujárride de la Cordillera Bética. Su secuencia litológica está compuesta por un conjunto inferior de migmatitas, gneises y esquistos, y por una formación superior de mármoles, blancos dolomíticos en la base y mármoles calizos azules hacia la parte superior, entre los que existe un tránsito gradual. La estructura de Sierra Blanca está formada por pliegues, generalmente isoclinales, con flancos invertidos que muestran

  17. Los deslizamientos de la cordillera neuquina al sur delos 38° S: suinducción

    Directory of Open Access Journals (Sweden)

    Emilio F. González Díaz

    2009-06-01

    Full Text Available Las conclusiones sobre losdeslizamientos individualizados en la cordillera neuquina (36°-38°S, (suinducción sísmica; rechazo de la consideración de sus depósitos como till,indujo a proyectar su estudio al sur de los 38°S. Se distinguieron inéditaszonas de deslizamientos, cuya promoción y contexto sismotectónico difieren delos reconocidos entre los 36°-38°S. Su estudio regional, que abarcó trescomarcas (Aluminé, Chapelco y Arroyo Limay Chico, comprobó el predominio delas corrientes de tierra sobre los deslizamientos rotacionales, siendo laexcepción tipológica la avalancha de rocas de Chapelco, definida por sumagnitud y morfología. Se interpretó una íntima relación entre sus ocurrenciasy la presencia del Miembro Arroyo Limay Chico (Formación Caleufu. Su litología(con matriz de arcillas expansivas, su particular comportamientofísico-mecánico ante su saturación por precipitaciones y su disposiciónsubyacente a planicies estructurales lávicas o conglomerádicas, determinaron sucarácter de factor intrínseco condicionante. El inductor de las prehistóricascorrientes de tierra (y aun de las actuales, ha sido las precipitacionesintensas. La infiltración de sus aguas redujo la cohesión y fricción de losmateriales, incrementó la presión del agua de los poros y la hidrostáticanormal a las pendientes, haciéndolas proclives a su desestabilización. Losdeslizamientos rotacionales son genéticamente relacionados con el socavamientobasal en los valles por erosión lateral fluvial y adicionalmente con lasprecipitaciones. En ambos casos influyeron la orientación de las pendientes(>insolación, el debilitamiento de abruptas laderas (artesas por esfuerzoshorizontales (lateral release y la pérdida postglaciaria del soporte oapoyo (debutressing que brindaban las lenguas glaciarias. Eldesprendimiento de la avalancha de rocas del Chapelco, ha sido relacionado conintensas precipitaciones o prolongados períodos lluviosos. Se

  18. Documenting and describing the redox evolution of the Neoproterozoic ocean: lessons from the Canadian Cordillera (Invited)

    Science.gov (United States)

    Johnston, D. T.; Poulton, S. W.; Langmuir, C. H.; MacDonald, F. A.; Chen, Z.; Knoll, A.

    2009-12-01

    The geological record of the Neoproterozoic preserves evidence for large-scale perturbations in Earth’s climate and changes in tectonic configuration. During the terminal Proterozoic, and within the context of these changes, Earth’s fluid envelope achieved a level of oxygenation that allowed for the evolution and subsequent radiation of complex multi-cellular life. As such, better constraining the geochemical evolution of the oceans and atmosphere throughout the entire Neoproterozoic will allow for a more mechanistic understanding of the links between changing environmental chemistry and biological innovation. Further, it will provide information on the relative timing of these changes and, where robust dates are available, estimates on the absolute rates of change (both chemical and biological). To this end, our ongoing work has focused on constructing high stratigraphic resolution geochemical records through mixed lithological packages of sedimentary rocks from eastern Alaska and the Canadian Cordillera. Here, we present detailed chemostratigraphic reconstructions of redox sensitive proxies, including Fe-speciation and trace element budgets, that provide an integrated window into Neoproterozoic marine oxidant budgets. These oxidant budgets then allow for the modeling of the relative influence of different aerobic and anaerobic microbial processes on the overall carbon cycle. Taken together, it is this cascade of microbial processes that drives remineralization reactions, the sum of which serves to counter-act organic carbon export, which is ultimately responsible for the buildup of O2. This simple framework serves as the foundation for our interpretation of Neoproterozoic biogeochemistry and informs our view of late Precambrian marine ecosystems. This approach can be further applied to more specific, and perhaps even more anomalous intervals of Neoproterozoic Earth history, including the Cryogenian Bitter Springs event and the Ediacaran Shuram anomaly; both

  19. Recent evolution and mass balance of Cordón Martial glaciers, Cordillera Fueguina Oriental

    Science.gov (United States)

    Strelin, Jorge; Iturraspe, Rodolfo

    2007-10-01

    Past and present glacier changes have been studied at Cordón Martial, Cordillera Fueguina Oriental, Tierra del Fuego, providing novel data for the Holocene deglaciation history of southern South America and extrapolating as well its future behavior based on predicted climatic changes. Regional geomorphologic and stratigraphic correlations indicate that the last glacier advance deposited the ice-proximal ("internal") moraines of Cordón Martial, around 330 14C yr BP, during the Late Little Ice Age (LLIA). Since then glaciers have receded slowly, until 60 years ago, when major glacier retreat started. There is a good correspondence for the past 100 years between the surface area variation of four small cirque glaciers at Cordón Martial and the annual temperature and precipitation data of Ushuaia. Between 1984 and 1998, Martial Este Glacier lost 0.64 ± 0.02 × 10 6 m 3 of ice mass (0.59 ± 0.02 × 10 6 m 3 w.e.), corresponding to an average ice thinning of 7.0 ± 0.2 m (6.4 ± 0.2 m w.e), according to repeated topographic mapping. More detailed climatic data have been obtained since 1998 at the Martial Este Glacier, including air temperature, humidity and solar radiation. These records, together with the monthly mass balance measured since March 2000, document the annual response of the Martial Este Glacier to the climate variation. Mass balances during hydrological years were positive in 2000, negative in 2001 and near equilibrium in 2002. Finally, using these data and the regional temperature trend projections, modeled for different future scenarios by the Atmosphere-Ocean Model (GISS-NASA/GSFC), potential climatic-change effects on this mountain glacier were extrapolated. The analysis shows that only the Martial Este Glacier may survive this century.

  20. Infrared Imaging and Modeling of Proglacial Stream Temperature in the Cordillera Blanca, Peru

    Science.gov (United States)

    Baker, E. A.; Lautz, L.; McKenzie, J. M.; Aubry-Wake, C.; Somers, L. D.; Wigmore, O.; Glose, A.; Glas, R. L.; Mark, B. G.

    2015-12-01

    In the tropical Andes, glacial meltwater is an important water resource for downstream communities, especially during the dry season. Due to climate change, glacial retreat is accelerating and straining already limited water resources in the region. It is hypothesized that groundwater storage and discharge will play a critical role in sustaining future river flows. To improve our understanding of the hydrologic fluxes in proglacial valleys of the tropical Andes, we monitored a ~1.2 km reach of the Quilcayhuanca River, in the Cordillera Blanca, Peru, using a high resolution infrared (IR) camera and in-stream temperature sensors. We positioned the IR camera on the southern valley wall, 96 m above the valley floor, and collected >700 IR images at 10 minute intervals over 5 days. We deployed 40 temperature sensors along the stream at ~25 m intervals and 10 sensors at additional control points throughout the surrounding valley, recording temperature at 10 minute intervals. Groundwater temperature was recorded in 6 wells in the study area. The reach had diurnal temperature fluctuations from ~4 to 13°C, but did not exhibit large longitudinal temperature differences. Stream temperature profiles within the water column show stream water is well mixed, improving the ability of the IR camera to accurately observe the stream temperature at this research site. Temperature sensors in 4 reach tributaries recorded warmer temperatures than the main channel. The daily temperatures of one tributary fluctuated within the range of the groundwater temperature (~9 to 11°C), while another tributary exhibited a range of ~18°C. A weather station in the study area recorded climate data (air temperature, humidity, wind speed, solar radiation) at 10 minute intervals. We used this field data as input for a spatial and temporal energy balance model of the reach. Our model demonstrates the utility of IR imagery to monitor stream temperatures and improves our understanding of energy fluxes in

  1. Ensayo de zonación sismotectónica en la Cordillera Ibérica. Depresión del Ebro y borde sur Pirenáico

    Directory of Open Access Journals (Sweden)

    Simon, J. L.

    1987-12-01

    Full Text Available Spatial relations between recent (Pliocene and Quaternary structures and seismic activity in the Iberian Chain, Ebro Basin and Outer Pyrenean Sierras are analysed. Starting from these relations, a seismotectonic zonation defining four main regions (Eastern Iberian Chain, Middle Iberian Chain, Outer Pyrenean Sierras-Carneros-Demanda Massif and Central sector of the Ebro Basin is stablished. Several zones and subzones with homogeneous characteristics from the seismotectonic point of view are differenciated within each of these four main regions. This zonation is the basis of an attempt to calculate seismic risk with a deterministic criterion.Se analizan las relaciones espaciales entre estructuras recientes (pliocenas y cuaternarias y actividad sísmica en el área de la Cordillera Ibérica, Depresión del Ebro y Sierras Exteriores Pirenaicas. A partir de ellas se realiza una zonación sismotectónica, definiendo cuatro regiones principales (Ibérica Oriental, Ibérica central, Sierras Exteriores-Macizo de Cameros-Demanda y sector central de la Depresión del Ebro y, en cada una de ellas, diferentes zonas y subzonas con características homogéneas desde el punto de vista sismotectónico. Esta zonación constituye la base de un ensayo de cálculo de riesgo sísmico con criterio determinista.

  2. Constraining Subsurface Structure and Composition Using Seismic Refraction Surveys of Proglacial Valleys in the Cordillera Blanca, Peru

    Science.gov (United States)

    Glas, R. L.; Lautz, L.; McKenzie, J. M.; Mark, B. G.; Baker, E. A.; Aubry-Wake, C.; Somers, L. D.; Wigmore, O.

    2015-12-01

    As tropical glaciers rapidly recede in response to climate change, the storage and discharge of groundwater will play an increasing role in regulating river baseflow, particularly during the dry season, when stream flow is currently sustained predominantly by glacial melt. Little is understood regarding the hydrogeologic processes controlling base flow characteristics of low-gradient proglacial valleys of the Cordillera Blanca in Northwestern Peru, which has the world's highest density of tropical glaciers. To better understand the processes of groundwater storage and discharge in proglacial meadows, we completed seismic refraction surveys in three representative valleys of the Cordillera Blanca range: the Quilcayhuanca, Yanamarey, and Pachacoto valleys. The locations of survey transects were chosen based on locations of previous sediment core sampling, GPR lines, and quantification of groundwater-surface water interaction derived from dye and temperature tracing experiments. The seismic surveys consisted of 48 vertical component geophones with 2.5 m spacing. Across the three representative valleys a total of 15 surveys were conducted, covering a distance of 1800 m in cross, down, and oblique-valley directions. Preliminary interpretation of the seismic refraction data indicates a maximum imaging depth of 16 m below land surface, and a transition from glacio-lacustrine sediments to buried saturated talus at a depth of 6 m in the Quilcayhuanca valley. The organic-rich glacio-lacustrine sediments in the Yanamarey valley have seismic velocities ranging from 300 to 800 m/s and are >16 m in thickness at mid- valley. Weathered metasedimentary bedrock in the Pachacoto valley was imaged at ~5 m below the valley surface, exhibiting a p-wave velocity of 3400 m/s. The knowledge of hydrogeologic structure derived from seismic refraction surveys will provide crucial boundary conditions for future groundwater models of the valleys of the Cordillera Blanca.

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

    Science.gov (United States)

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

    2016-01-01

    Seasonal snow cover is the primary water source for human use and ecosystems along the extratropical Andes Cordillera. Despite its importance, relatively little research has been devoted to understanding the properties, distribution and variability of this natural resource. This research provides high-resolution (500 m), daily distributed estimates of end-of-winter and spring snow water equivalent over a 152 000 km2 domain that includes the mountainous reaches of central Chile and Argentina. Remotely sensed fractional snow-covered area and other relevant forcings are combined with extrapolated data from meteorological stations and a simplified physically based energy balance model in order to obtain melt-season melt fluxes that are then aggregated to estimate the end-of-winter (or peak) snow water equivalent (SWE). Peak SWE estimates show an overall coefficient of determination R2 of 0.68 and RMSE of 274 mm compared to observations at 12 automatic snow water equivalent sensors distributed across the model domain, with R2 values between 0.32 and 0.88. Regional estimates of peak SWE accumulation show differential patterns strongly modulated by elevation, latitude and position relative to the continental divide. The spatial distribution of peak SWE shows that the 4000-5000 m a.s.l. elevation band is significant for snow accumulation, despite having a smaller surface area than the 3000-4000 m a.s.l. band. On average, maximum snow accumulation is observed in early September in the western Andes, and in early October on the eastern side of the continental divide. The results presented here have the potential of informing applications such as seasonal forecast model assessment and improvement, regional climate model validation, as well as evaluation of observational networks and water resource infrastructure development.

  4. The behavioral ecology and breeding biology of the andean sparrow, zonotrichia capensis

    OpenAIRE

    Miller, Alden H.; Miller, Virginia D.

    2012-01-01

    La ecología de comportamiento y la biología de la reproducción de los Gorriones Andinos "copetones" (Zonotrichia capensis) fueron estudiadas a lo largo de un año en una población ubicada a 2.000 metros de altura en la Cordillera Occidental de Colombia. Se capturaron cerca de 170 individuos, y para hacer posible su identificación en el campo se marcaron convenientemente. En varias ocasiones se Iogró la recaptura de muchos de éstos con el objeto de estudiar los cambios de plumaje y ciclos repro...

  5. 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.

  6. Variabilidad espacial de los atributos de la capa arable de un inceptisol del piedemonte de la cordillera oriental (casanare, colombia)

    OpenAIRE

    Peña, Ricardo; Rubiano, Yolanda; Peña, Andrés; Chaves, Bernardo

    2009-01-01

    El objetivo de este trabajo fue estudiar la variabilidad espacial de los atributos del suelo, enfocado a optimizar futuros muestreos en suelos similares. El estudio se realizó en una superficie de 58 ha, ubicada en Tauramena, departamento de Casanare, Orinoquia colombiana. El suelo del estudio corresponde a un Oxic Dystrudept de textura franco arenosa a franco arcillosa, localizado sobre un abanico de terraza del piedemonte de la cordillera Oriental. A través del análisis del semivariograma y...

  7. Clasificación de yeso mediante imágenes ASTER en la Cordillera Principal Mendocina

    OpenAIRE

    José F Mescua

    2010-01-01

    Se presenta una metodología para obtener el mapa de distribución de yeso con imágenes satelitales ASTER. Se utilizaron imágenes con nivel de procesamiento ASTERL3A correspondientes a dos áreas de la Cordillera Principal mendocina. La estratigrafía de las áreas de estudio se encuentra compuesta por una espesa sucesión sedimentaria mesozoica, volcanitas cenozoicas y depósitos cuaternarios. Dentro de los depósitos mesozoicos se encuentra la Formación Auquilco, integrada por yeso y anhidrita. El ...

  8. An enigmatic frog of the genus Atelopus (Family Bufonidae) from Parque Nacional Chirripó, Cordillera de Talamanca, Costa Rica.

    Science.gov (United States)

    Savage, Jay M; Bolaños, Federico

    2009-01-01

    A distinctive new species of Atelopus is described from Parque Nacional Chirrip6 Grande, Cordillera de Talamanca (3,400-3,500 m). It closely resembles populations of the Atelopus ignescens complex from the Andes of northern Ecuador and southern Colombia. It differs most significantly from these frogs in the pattern of spiculae and coni development on the throat, chest, hands and feet. The Costa Rican species appears to be an outlier of the complex inexplicably separated geographically from its nearest allies by an over land distance of about 1,600 km. PMID:19637715

  9. Pertinent spatio-temporal scale of observation to understand sediment yield control factors in the Andean Region: the case of the Santa River (Peru)

    Science.gov (United States)

    Morera, S. B.; Condom, T.; Vauchel, P.; Guyot, J.-L.; Galvez, C.; Crave, A.

    2013-01-01

    Hydro-sedimentology development is a great challenge in Peru due to limited data as well as sparse and confidential information. Consequently, little is known at present about the relationship between the El Niño Southern Oscillation (ENSO), precipitation, runoff, land use and the sediment transport dynamics. The aim of this paper is to bridge this gap in order to quantify and understand the signal of magnitude and frequency of the sediment fluxes from the central western Andes; also, to identify the main erosion control factor and its relevance. The Tablachaca River (3132 km2) and the Santa River (6815 km2), two mountainous Andean catchments that are geographically close to each other, both showed similar statistical daily rainfall and discharge variability but high contrast in sediment yield (SY). In order to investigate which factors are of importance, the continuous water discharge and hourly suspended sediment concentrations (SSC) of the Santa River were studied. Firstly, the specific sediment yield (SSY) at the continental Andes range scale for the Pacific side is one of the highest amounts (2204 t km2 yr-1). Secondly, no relationship between the water discharge (Q) and El Niño/La Niñ a events is found over a 54 yr time period. However, the Santa Basin is highly sensitive during mega Niños (1982-1983 and 1997-1998). Lastly, dispersed micro-mining and mining activity in specific lithologies are identified as the major factors that control the high SSY. These remarks make the Peruvian coast key areas for future research on Andean sediment rates.

  10. The Bolivian Source Rocks. Sub Andean Zone. Madre de Dios. Chaco Les roches mères de Bolivie. Subandin. Madre de Dios. Chaco

    Directory of Open Access Journals (Sweden)

    Diaz Martinez E.

    2006-11-01

    Full Text Available A complete study of source-rock geochemical data has been carried out for the Bolivian foothills and foreland (Sub Andean Zone, Chaco and Madre de Dios in order to quantify the petroleum potential of the area. Overall available data have been compiled in a database, and a synthesis of the results is presented here. Besides the classical mid-Devonian source rocks (Tequeje Fm in the north, Limoncito Fm in the center and Los Monos Fm in the south, others may be just as important : theTomachi Fm (late Devonian in the north of the country and the Copacabana Fm. (late Carboniferous-early Permian in the northern Sub Andean Zone. Both present an excellent potential with S2 up to 40 mg HC/g and average values larger than 10 mg HC/g on few hundred meters. The latest Cretaceous (Flora Fm in the northern Sub Andean Zone also presents locally a high potential but has almost no influence, its thickness being quite reduced. Almost all the source rocks matured during the Neogene due to the subsidence in the Andean foreland and, locally, in the piggyback basins, and are thus involved in the current petroleum system. Silurian and Lower Paleozoic units also contain thick shale beds, but these source rocks were mature before the Jurassic in most of the country, except in the Chaco, the Boomerang and the central Sub Andean Zone, where the Silurian is not nowadays overmature and may play an important role. The different zones are compared based on their Source Potential Index (SPI which indicates that the richest areas are the northern Sub Andean Zone and the Madre de Dios basin with SPI greater than 10 t/m². Since these two areas remain almost unexplored and, at least for the northern Sub Andean zone, present very large structures, these results allow to be optimistic about the possibilities for future exploration. Une base de données géochimiques a été mise en place entre 1994 et 1995 à YPFB (Yacimientos Petrolíferos Fiscales Bolivianos afin de regrouper les

  11. Landscape evolution within a retreating volcanic arc, Costa Rica, Central America

    Science.gov (United States)

    Marshall, Jeffrey S.; Idleman, Bruce D.; Gardner, Thomas W.; Fisher, Donald M.

    2003-05-01

    Subduction of hotspot-thickened seafloor profoundly affects convergent margin tectonics, strongly affecting upper plate structure, volcanism, and landscape evolution. In southern Central America, low-angle subduction of the Cocos Ridge and seamount domain largely controls landscape evolution in the volcanic arc. Field mapping, stratigraphic correlation, and 40Ar/39Ar geochronology for late Cenozoic volcanic rocks of central Costa Rica provide new insights into the geomorphic response of volcanic arc landscapes to changes in subduction parameters (slab thickness, roughness, dip). Late Neogene volcanism was focused primarily along the now-extinct Cordillera de Aguacate. Quaternary migration of the magmatic front shifted volcanism northeastward to the Caribbean slope, creating a new topographic divide and forming the Valle Central basin. Stream capture across the paleo Aguacate divide led to drainage reversal toward the Pacific slope and deep incision of reorganized fluvial networks. Pleistocene caldera activity generated silicic ash flows that buried the Valle Central and descended the Tárcoles gorge to the Orotina debris fan at the coast. Growth of the modern Cordillera Central accentuated relief along the new divide, establishing the Valle Central as a Pacific slope drainage basin. Arc migration, relocation of the Pacific-Caribbean drainage divide, and formation of the Valle Central basin resulted from slab shallowing as irregular, hotspot-thickened crust entered the subduction zone. The geomorphic evolution of volcanic arc landscapes is thus highly sensitive to changes in subducting plate character.

  12. The great Atacama flood of 2001 and its implications for Andean hydrology

    Science.gov (United States)

    Houston, John

    2006-02-01

    In February 2001, widespread flooding occurred throughout the Atacama Desert of northern Chile and southern Peru. It was particularly severe in the Río Loa basin, where roads and bridges were disrupted and the town of Calama inundated. The instantaneous peak flow in the Río Salado, a tributary of the Río Loa, reached 310 m3 s-1, an order of magnitude higher than any previously recorded event. The flood is estimated to have a return period of 100-200 years and is shown to have been caused by intense, long-duration rainfall in the western Cordillera associated with La Niña. The surface water response is typical of arid areas and highly dependent on antecedent conditions, but is quite different in perennial and ephemeral catchments. Ephemeral flood flows suffer high transmission losses, recharging phreatic aquifers. Perennial rivers have lower runoff coefficients, but baseflow levels remained high after the event for several months due to bank storage rebound and interflow. Extremely high energies of 3000 W m-2 were generated by the floods in the Cordillera, becoming less in the Precordillera and downstream. Erosion and sediment transport were consequently highest in the upper and middle reaches of the rivers, with mixed erosion-deposition in the lowest reach. The new insights gained from the interpretation and quantification of this event have important implications for palaeoenvironmental analysis, hazard management, water resource evaluation and the palaeohydrological evolution of the Andes.

  13. Recent trends in annual snowline variations in the northern wet outer tropics: case studies from southern Cordillera Blanca, Peru

    Science.gov (United States)

    Veettil, Bijeesh Kozhikkodan; Wang, Shanshan; Bremer, Ulisses Franz; de Souza, Sergio Florêncio; Simões, Jefferson Cardia

    2016-03-01

    This paper describes the changes in the annual maximum snowlines of a selected set of mountain glaciers at the southern end of the Cordillera Blanca between 1984 and 2015 using satellite images. Furthermore, we analysed the existing glacier records in the Cordillera Blanca since the last glacial maximum to understand the evolution of glaciers in this region over a few centuries. There was a rise in the snowline altitude of glaciers in this region since the late 1990s with a few small glacier advances. Historical to the present El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) records were also analysed to understand whether there was a teleconnection between the glacier fluctuations in the region and the phase changes of ENSO and PDO. We also assessed the variations in three important climatic parameters that influence the glacier retreat—temperature, precipitation, and relative humidity—over a few decades. We calculated the anomalies as well as the seasonal changes in these variables since the mid-twentieth century. There was an increase in temperature during this period, and the decrease in precipitation was not so prominent compared with the temperature rise. There was an exceptionally higher increase in relative humidity since the early 2000s, which is relatively higher than that expected due to the observed rate of warming, and this increase in humidity is believed to be the reason behind the unprecedented rise in the snowline altitudes since the beginning of the twenty-first century.

  14. Tectonic and unroofing history of Neogene Manantiales foreland basin deposits, Cordillera Frontal (32°30'S), San Juan Province, Argentina

    Science.gov (United States)

    Pérez, Daniel J.

    2001-12-01

    The Miocene Manantiales foreland basin is located in Cordillera Frontal of San Juan, between 32°30' and 33°S. The unroofing study of the synorogenic Miocene deposits provides information about the structural evolution of Cordón de La Ramada fold-and-thrust belt. These Tertiary deposits are represented by the Chinches Formation and comprise seven members (Tc0-Tc6). They are the result of the uplift of Mesozoic sequences that crop out in La Ramada fold-and-thrust belt of the Cordillera Principal. Quaternary deposits unconformably overlying the Chinches Formation are composed of granitic and rhyolitic blocks, and represent the final uplift of the Cordón del Espinacito and a series of out-of-sequence thrusts. The unroofing studies also provide sufficient information to establish the out-of-sequence timing of the deformation at this latitude. Initial deposition of the Tertiary deposits can be dated at about 20 Ma, or early Miocene. Andesitic lavas dated in 9.2±0.3, 10.7±0.7, and 12.7±0.7 Ma unconformably overlie the structure of La Ramada fold-and-thrust belt. These facts constrain the uplift of the High Andes between 20 and 10 Ma at this latitude. The unconformity between Tertiary and Quaternary deposits suggests final uplift during Pliocene-Pleistocene times.

  15. Simultaneous batholith emplacement, terrane/continent collision, and oroclinal bending in the Blue Mountains Province, North American Cordillera

    Science.gov (United States)

    Žák, Jiří; Verner, Kryštof; Tomek, Filip; Holub, František V.; Johnson, Kenneth; Schwartz, Joshua J.

    2015-06-01

    The North American Cordillera is a classic example of accretionary orogen, consisting of multiple oceanic terranes attached to the western margin of Laurentia during the Mesozoic times. Although the Cordillera is linear for most parts, terrane boundaries are at a high angle to the overall structural grain in several segments of the orogen, which has been a matter of longstanding controversy as to how and when these orogenic curvatures formed. This paper discusses mechanisms, kinematics, and timing of initiation of one of these major curvatures, the Blue Mountains Province in northeastern Oregon. Here magmatic fabric patterns and anisotropy of magnetic susceptibility in the Wallowa batholith record three phases of progressive deformation of the host Wallowa terrane during Early Cretaceous. First is terrane-oblique ~NE-SW shortening, interpreted as recording attachment of the amalgamated oceanic and fringing terranes to the continental margin during dextral convergence at ~140 Ma. Deformation subsequently switched to pure shear-dominated ~NNE-SSW shortening associated with crustal thickening, caused by continued impingement of the amalgamated Blue Mountains superterrane into a presumed westward concave reentrant in the continental margin at ~135-128 Ma. Upon impingement (at ~126 Ma), the northern portion of the superterrane became "locked," leading to reorientation of the principal shortening direction to ~NNW-SSE while its still deformable southern portion rotated clockwise about a vertical axis. We thus propose oblique bending as the main mechanism of the orocline formation whereby horizontal compressive forces resulting from plate convergence acted at an angle to the terrane boundaries.

  16. Coupling data from U-series and 10Be CRN to evaluate soil steady-state in the Betic Cordillera

    Science.gov (United States)

    Schoonejans, Jerome; Vanacker, Veerle; Opfergelt, Sophie; Granet, Mathieu; Chabaux, François

    2015-04-01

    The regolith mantel is produced by weathering of bedrock through physical and biochemical processes. At the same time, the upper part of the regolith is eroded by gravity mass movements, water and wind erosion. Feedback's between production and erosion of soil material are important for soil development, and are essential to reach long-term steady-state in soil chemical and physical properties. Nowadays, long-term denudation rates of regolith can be quantified by using in-situ cosmogenic nuclides (CRN). If the soil thickness remains constant over sufficiently long time, soil production rates can be determined. However, the a priori assumption of long-term steady-state can be questionable in highly dynamic environments. In this study, we present analytical data from two independent isotopic techniques, in-situ cosmogenic nuclides and Uranium series disequilibrium. The disequilibrium of Uranium isotopes (238U, 234U, 230Th, 226Ra) is an alternative method that allows assessing soil formation rates through isotopic analysis of weathering products. Nine soil profiles were sampled in three different mountain ranges of the Betic Cordillera (SE Spain): Sierra Estancias, Filabres, Cabrera. All soils overly fractured mica schist and are very thin (analytical techniques is useful to further unravel the mechanisms of chemical and physical weathering in such dynamic environments. Bellin, N., Vanacker, V., and Kubik, P. W., 2014, Denudation rates and tectonic geomorphology of the Spanish Betic Cordillera: Earth and Planetary Science Letters, v. 390, p. 19-30.

  17. Constraints on the origin and evolution of magmas in the Payún Matrú Volcanic Field, Quaternary Andean Back-arc of Western Argentina

    NARCIS (Netherlands)

    Hernando, I.R.; Aragón, E.; Frei, R.; González, P.D.; Spakman, W.

    2014-01-01

    The Payún Matrú Volcanic Field (Pleistocene–Holocene) is located in the Andean back-arc of the Southern Volcanic Zone, western Argentina, and is contemporaneous with the Andean volcanic arc at the same latitude. It includes two polygenetic, mostly trachytic volcanoes: Payún Matrú (with a summit cald

  18. Transverse Zones in the Eastern Cordillera (Colombia): An example in the Zipaquira Anticline

    Science.gov (United States)

    Garcia Delgado, H. S.; Jimenez, G.

    2014-12-01

    model for the Eastern Cordillera. Our goal is related the ZA and the transverse zones using Anisotropy of Magnetic Susceptibility (AMS) and paleomagnetism to unraveal the kinematic evolution of the anticline and the temporal relationship between the transverse zones and the ZA.

  19. ZONIFICACIÓN AGROECOLÓGICA DE LA CORDILLERA DE GUANIGUANICO

    Directory of Open Access Journals (Sweden)

    F. Soto

    2007-01-01

    Full Text Available El desarrollo de un país necesita de una planificación de la actividad agrícola, que si se quiere que sea económicamente rentable, debe ceñirse a la realidad ecológica de las áreas de producción. En este sentido, la zonificación agroecológica es una de las principales herramientas para disminuir los riesgos a los que está sometida la agricultura. Teniendo en cuenta estos elementos, se procedió a realizar la zonificación agroecológica de la cordillera de Guaniguanico. Se tuvo información de ocho estaciones meteorológicas y 62 pluviómetros de la red del Instituto Nacional de Recursos Hidráulicos, con lo cual se llevó a cabo la zonificación climática; se estudiaron 371 000 ha, en las que se obtuvo información de más de 500 perfiles con planillas completas, lo que permitió caracterizar los suelos desde los puntos de vista físico, químico y mineralógico. Se utilizaron diferentes Sistemas de Información Geográfica (SIG, para establecer las relaciones entre los distintos parámetros estudiados y llegar a la zonificación agroecológica. A partir del análisis de la información sobre el comportamiento de los cultivos, se establecieron las bases para la zonificación, tomándose como elementos fundamentales del clima la temperatura y la lluvia; ambos se combinaron y se definieron los potenciales de rendimiento para cada condición. El otro elemento discriminante fue el suelo; en primer lugar, se tuvieron en cuenta los tipos de suelo y su aptitud para el cultivo y posteriormente se consideró la profundidad efectiva.

  20. Timing and paleoclimatic significance of Holocene glacier fluctuations in the Cordillera Vilcabamba of southern Peru

    Science.gov (United States)

    Licciardi, J. M.; Taggart, J. R.; Schaefer, J. M.; Lund, D. C.

    2009-12-01

    Past fluctuations in climatically sensitive tropical glaciers provide important insight into regional paleoclimatic trends and forcings, but well-dated chronologies are scarce, particularly during the Holocene. We have established precise cosmogenic 10Be surface exposure ages of moraine sequences in the Cordillera Vilcabamba (13°20’S latitude), located in the outer tropics of southern Peru. Results indicate the dominance of two major glacial culminations and associated climatic shifts in the Vilcabamba, including an early Holocene glacial interval and a somewhat less extensive glaciation late in the ‘Little Ice Age’ (LIA) period. Lichenometric measurements on the youngest moraines support the 10Be ages, but uncertainties in the lichen ages arise from the lack of a local lichen growth curve. The Peruvian glacier chronologies differ from a recently-developed New Zealand record but are broadly correlative with well-dated glacial records in Europe, suggesting climate linkages between the tropics and the North Atlantic region. For the latest Holocene, our leading hypothesis is that climate forcings involving southward migration of the Atlantic Intertropical Convergence Zone can explain concurrent glaciations in tropical South America and northern high latitudes, but the influence of other climate drivers such as the El Niño/Southern Oscillation may have also played a role. Estimated differences between equilibrium-line altitudes (ELAs) on modern glaciers and those inferred for expanded latest Holocene glaciers reveal an ELA rise of 165-200 m since the LIA, suggesting that temperatures 1.1-1.3°C cooler than present could have sustained glaciers at their LIA maximum positions if temperature was the only control, and thus providing an upper bound on temperature depression during the LIA. However, further work is required to constrain the likely role of precipitation changes. These new Peruvian glacier chronologies and ELA reconstructions complement ice core and

  1. Deforestation and benthic indicators: how much vegetation cover is needed to sustain healthy Andean streams?

    Science.gov (United States)

    Iñiguez-Armijos, Carlos; Leiva, Adrián; Frede, Hans-Georg; Hampel, Henrietta; Breuer, Lutz

    2014-01-01

    Deforestation in the tropical Andes is affecting ecological conditions of streams, and determination of how much forest should be retained is a pressing task for conservation, restoration and management strategies. We calculated and analyzed eight benthic metrics (structural, compositional and water quality indices) and a physical-chemical composite index with gradients of vegetation cover to assess the effects of deforestation on macroinvertebrate communities and water quality of 23 streams in southern Ecuadorian Andes. Using a geographical information system (GIS), we quantified vegetation cover at three spatial scales: the entire catchment, the riparian buffer of 30 m width extending the entire stream length, and the local scale defined for a stream reach of 100 m in length and similar buffer width. Macroinvertebrate and water quality metrics had the strongest relationships with vegetation cover at catchment and riparian scales, while vegetation cover did not show any association with the macroinvertebrate metrics at local scale. At catchment scale, the water quality metrics indicate that ecological condition of Andean streams is good when vegetation cover is over 70%. Further, macroinvertebrate community assemblages were more diverse and related in catchments largely covered by native vegetation (>70%). Our results suggest that retaining an important quantity of native vegetation cover within the catchments and a linkage between headwater and riparian forests help to maintain and improve stream biodiversity and water quality in Andean streams affected by deforestation. This research proposes that a strong regulation focused to the management of riparian buffers can be successful when decision making is addressed to conservation/restoration of Andean catchments.

  2. The Patagonian Orocline: New paleomagnetic data from the Andean magmatic arc in Tierra del Fuego, Chile

    Science.gov (United States)

    Cunningham, W. Dickson; Klepeis, Keith A.; Gose, Wulf A.; Dalziel, Ian W. D.

    1991-09-01

    The Hardy Formation is a 1300-m-thick succession of Upper Jurassic-Lower Cretaceous volcaniclastic sedimentary rocks interbedded with lava flows on Hoste Island at the southernmost tip of South America (55.5°S, 291.8°E). The strata are gently folded and metamorphosed to the prehnite-pumpellyite grade. A well-defined characteristic direction of magnetization, carried by magnetite, was readily identified in 95 samples from seven sites. At a given site, the directions group slightly better without structural correction. However, the means of the seven sites cluster better without tilt correction at the 99% significance level, implying that the magnetization postdates the folding event. It is most likely that the magnetization was acquired during the mid- to Late Cretaceous Andean orogeny that involved the folding and emplacement of the Patagonian Batholith. The fact that all samples are normally magnetized supports this age assignment. The pole position of 42.9°N, 156.6°E, α95=3.3° implies that the sampling area has rotated counterclockwise relative to cratonic South America by 90.1±11.9° with no significant flattening of inclination (F=1.9 ± 3.7°). Geologic considerations indicate that the rotation involved the entire Andean magmatic arc in Tierra Del Fuego. The results support interpretation of the Hardy Formation as part of the Andean magmatic arc deposited on the Pacific side of the Late Jurassic-Early Cretaceous Rocas Verdes marginal basin. Oroclinal bending of the arc in southernmost South America accompanied inversion of the marginal basin and the development of a Late Cretaceous-Cenozoic left-lateral transform system (South America-Antarctica) that later developed into the North Scotia Ridge.

  3. Identifying positive selection candidate loci for high-altitude adaptation in Andean populations

    Directory of Open Access Journals (Sweden)

    Bigham Abigail W

    2009-12-01

    Full Text Available Abstract High-altitude environments (>2,500 m provide scientists with a natural laboratory to study the physiological and genetic effects of low ambient oxygen tension on human populations. One approach to understanding how life at high altitude has affected human metabolism is to survey genome-wide datasets for signatures of natural selection. In this work, we report on a study to identify selection-nominated candidate genes involved in adaptation to hypoxia in one highland group, Andeans from the South American Altiplano. We analysed dense microarray genotype data using four test statistics that detect departures from neutrality. Using a candidate gene, single nucleotide polymorphism-based approach, we identified genes exhibiting preliminary evidence of recent genetic adaptation in this population. These included genes that are part of the hypoxia-inducible transcription factor (HIF pathway, a biochemical pathway involved in oxygen homeostasis, as well as three other genomic regions previously not known to be associated with high-altitude phenotypes. In addition to identifying selection-nominated candidate genes, we also tested whether the HIF pathway shows evidence of natural selection. Our results indicate that the genes of this biochemical pathway as a group show no evidence of having evolved in response to hypoxia in Andeans. Results from particular HIF-targeted genes, however, suggest that genes in this pathway could play a role in Andean adaptation to high altitude, even if the pathway as a whole does not show higher relative rates of evolution. These data suggest a genetic role in high-altitude adaptation and provide a basis for genotype/phenotype association studies that are necessary to confirm the role of putative natural selection candidate genes and gene regions in adaptation to altitude.

  4. Analysis of the drought resilience of Andosols on southern Ecuadorian Andean páramos

    Directory of Open Access Journals (Sweden)

    V. Iñiguez

    2015-11-01

    Full Text Available The neotropical Andean grasslands above 3500 m a.s.l. known as "páramo" offer remarkable ecological services for the Andean region. Most important is the water supply – of excellent quality – to many cities and villages established in the lowlands of the inter-Andean valleys and to the coast. However, the páramo ecosystem is under constant and increased threat by human activities and climate change. In this paper we study the resilience of its soils for drought periods during the period 2007–2013. In addition, field measurements and hydrological conceptual modelling at the catchment-scale are comparing two contrasting catchments in the southern Ecuadorian Andes. Both were intensively monitored during two and a half years (2010–2012 in order to analyse the temporal variability of the soil moisture storage. A typical catchment on the páramo at 3500 m a.s.l. was compared to a lower grassland one at 2600 m a.s.l. The main aim was to estimate the resilience capacity of the soils during a drought period and the recovery during a subsequent wet period. Local soil water content measurements in the top soil (first 30 cm through TDR were used as a proxy for the catchment's average soil moisture storage. The local measurements were compared to the average soil water storage as estimated by the probabilistic soil moisture (PDM model. This conceptual hydrological model with 5 parameters was calibrated and validated for both catchments. The study reveals the extraordinary resilience capacity of this type of shallow organic soils during the droughts in 2009 and 2010. During these droughts, the soil water content dropped from a normal value of about 0.80 to ~ 0.60 cm3 cm−3, while the recovery time was only two to three months.

  5. Deforestation and benthic indicators: how much vegetation cover is needed to sustain healthy Andean streams?

    Directory of Open Access Journals (Sweden)

    Carlos Iñiguez-Armijos

    Full Text Available Deforestation in the tropical Andes is affecting ecological conditions of streams, and determination of how much forest should be retained is a pressing task for conservation, restoration and management strategies. We calculated and analyzed eight benthic metrics (structural, compositional and water quality indices and a physical-chemical composite index with gradients of vegetation cover to assess the effects of deforestation on macroinvertebrate communities and water quality of 23 streams in southern Ecuadorian Andes. Using a geographical information system (GIS, we quantified vegetation cover at three spatial scales: the entire catchment, the riparian buffer of 30 m width extending the entire stream length, and the local scale defined for a stream reach of 100 m in length and similar buffer width. Macroinvertebrate and water quality metrics had the strongest relationships with vegetation cover at catchment and riparian scales, while vegetation cover did not show any association with the macroinvertebrate metrics at local scale. At catchment scale, the water quality metrics indicate that ecological condition of Andean streams is good when vegetation cover is over 70%. Further, macroinvertebrate community assemblages were more diverse and related in catchments largely covered by native vegetation (>70%. Our results suggest that retaining an important quantity of native vegetation cover within the catchments and a linkage between headwater and riparian forests help to maintain and improve stream biodiversity and water quality in Andean streams affected by deforestation. This research proposes that a strong regulation focused to the management of riparian buffers can be successful when decision making is addressed to conservation/restoration of Andean catchments.

  6. Pollen-based 17-kyr forest dynamics and climate change from the Western Cordillera of Colombia: no-analogue associations and temporarely lost biomes

    NARCIS (Netherlands)

    C.A. Velásquez-R.; H. Hooghiemstra

    2013-01-01

    A 17 kyr long pollen record from the unexplored Western Cordillera of Colombia (Páramo de Frontino; 3460 m elevation) shows vegetation change and inferred climate dynamics at ~ 125 yr resolution. The cold and wet Lateglacial showed well-defined stadials and interstadials. At the transition to the Ho

  7. U-Pb geochronology of modern river sands from the flat-slab segment of the southern central Andes, Argentina, 29-31°S: Implications for Neogene foreland and hinterland basin evolution

    Science.gov (United States)

    Capaldi, T.; Horton, B. K.; McKenzie, R.; Stockli, D. F.

    2015-12-01

    This study investigates how Andean river sediments in the flat-slab segment of western Argentina record active mixing of lithologically and geochemically distinct source regions comprising the Principal Cordillera, Frontal Cordillera, Precordillera fold-thrust belt, Sierras Pampeanas basement uplifts, and recycled Neogene basin fill. Detrital zircon U-Pb geochronological results for modern river sands discriminate variations from hinterland source regions, through river tributaries and main trunks of the Bermejo, Jachal, San Juan, and Mendoza rivers, and their respective fluvial megafans within the active foreland basin. Proportions of proximal zircon populations in the hinterland trunk rivers (with extensive Permian-Triassic and Cenozoic igneous exposures) diminish downstream with progressive contributions from the frontal Precordillera fold-thrust belt (dominantly Paleozoic sedimentary rocks) and Pampean basement uplifts. However, this systematic downstream dilution is perturbed in several catchments by significant recycling of older foreland basin fill. The degree of recycling depends on the position and extent of Oligocene-Pliocene exposures within the catchments. To discern the effects of the variable detrital zircon sources, multiple statistical methods are utilized. Quantitative comparisons suggest that variations in detrital zircon age distributions among the modern sands, and with older foreland basin fill and exposed bedrock, are dependent on spatial and temporal variations in exhumation and drainage network evolution within their respective Andean catchments. The present surface area of competing source regions and the configuration of hinterland tributary rivers largely dictate the degree of downstream dilution and/or recycling. This study provides a modern analogue and baseline for reconstructing Neogene shifts in foreland basin provenance, depositional systems, and drainage configurations during a critical transition to flat-slab subduction.

  8. [Decriminalizing traditional Andean medicine: an interview with Walter Álvarez Quispe].

    Science.gov (United States)

    Quispe, Walter Álvarez; Loza, Carmen Beatriz

    2014-01-01

    Walter Álvarez Quispe, a Kallawaya healer and biomedical practitioner specializing in general surgery and gynecology, presents the struggle of traditional and alternative healers to get their Andean medical systems depenalized between 1960 and 1990. Bolivia was the first country in Latin America and the Caribbean to decriminalize traditional medicine before the proposals of the International Conference on Primary Health Care (Alma-Ata, 1978). The data provided by the interviewee show that the successes achieved, mainly by the Kallawayas, stem from their own independent initiative. These victories are not the result of official policies of interculturality in healthcare, although the successes achieved tend to be ascribed to them.

  9. The electronic contract formation in the framework of the Andean Community

    Directory of Open Access Journals (Sweden)

    William David Hernández

    2012-12-01

    Full Text Available The influence of the Information and Communication Technology (ICT in all the aspects of the society is an unquestionable fact that implies, for the Law, the inescapable responsibility of fostering the fulfillment of the declarations or objectives of the Society of Information. Today´s world, framed in a process of globalization and regional integration, heads to the normative harmonization. In line with the above, the present document studies the elements supporting the normative unification concerning the formation of the contract by electronic means in the Andean Community.

  10. Vascular Endothelial Growth Factor-A Is Associated with Chronic Mountain Sickness in the Andean Population

    OpenAIRE

    Espinoza, Jose R.; Alvarez, Giancarlo; León-Velarde, Fabiola; Ju Preciado, Hugo F.; Macarlupu, Jose-Luis; Rivera-Ch, Maria; Rodriguez, Jorge; Favier, Judith; Gimenez-Roqueplo, Anne-Paule; Richalet, Jean-Paul

    2014-01-01

    Espinoza, Jose R., Giancarlo Alvarez, Fabiola León-Velarde, Hugo F. Ju Preciado, Jose-Luis Macarlupu, Maria Rivera-Ch, Jorge Rodriguez, Judith Favier, Anne-Paule Gimenez-Roqueplo, and Jean-Paul Richalet. Vascular endothelial growth factor-A is associated with chronic mountain sickness in Andean population. High Alt Med Biol. 15:146–154, 2014.—A study of chronic mountain sickness (CMS) with a candidate gene—vascular endothelial growth factor A (VEGFA)—was carried out in a Peruvian population l...

  11. Physics in the Andean Countries: A Perspective from Condensed Matter, Novel Materials and Nanotechnology

    Science.gov (United States)

    Prieto, P.

    2009-05-01

    We will discuss the current state of R&D in the fields of condensed matter, novel materials, and nanotechnology in the Andean nations. We will initially consider Latin America and the Caribbean (LAC) to then visualize individual developments, as well as those for the region as a whole in these fields of knowledge in each of the nations constituting the Andean Region (Bolivia, Ecuador, Chile, Venezuela, Peru, and Colombia). Based on Science & Technology watch exercises in the countries involved, along with the Iberian American and Inter-American Science & Technology Network of Indicators (Red de indicadores de Ciencia y Tecnolog'ia (RICYT) iberoamericana e interamericana)1, we will reveal statistical data that will shed light on the development in the fields mentioned. As will be noted, total R&D investment in Latin American and Caribbean countries remained constant since 1997. In spite of having reached a general increase in publications without international collaboration in LAC nations, the countries with greatest research productivity in Latin America (Argentina, Mexico, Brazil, and Chile) have strengthened their international collaboration with the United States, France, Germany, and Italy through close links associated with the formation processes of their researchers. Academic and research integration is evaluated through joint authorship of scientific articles, evidencing close collaboration in fields of research. This principle has been used in the creation of cooperation networks among participating nations. As far as networks of research on condensed matter, novel materials, and nanotechnology, the Andean nations have not consolidated a regional network allowing permanent and effective cooperation in research and technological development; as would be expected, given their idiomatic and cultural similarities, their historical background, and geographical proximity, which have been integrating factors in other research areas or socio-economic aspects. This

  12. [Decriminalizing traditional Andean medicine: an interview with Walter Álvarez Quispe].

    Science.gov (United States)

    Quispe, Walter Álvarez; Loza, Carmen Beatriz

    2014-01-01

    Walter Álvarez Quispe, a Kallawaya healer and biomedical practitioner specializing in general surgery and gynecology, presents the struggle of traditional and alternative healers to get their Andean medical systems depenalized between 1960 and 1990. Bolivia was the first country in Latin America and the Caribbean to decriminalize traditional medicine before the proposals of the International Conference on Primary Health Care (Alma-Ata, 1978). The data provided by the interviewee show that the successes achieved, mainly by the Kallawayas, stem from their own independent initiative. These victories are not the result of official policies of interculturality in healthcare, although the successes achieved tend to be ascribed to them. PMID:25606737

  13. El clima de la vertiente del Pacífico de los Andes Centrales y sus implicaciones geomorfológicas El clima de la vertiente del Pacífico de los Andes Centrales y sus implicaciones geomorfológicas

    Directory of Open Access Journals (Sweden)

    Jose Úbeda Palenque

    2008-12-01

    Full Text Available Climate studies are of main importance to explain the external geodynamics of the Pacific Basin of the Central Andes between 15°S and 19°S. This is because the processes by which the relief modeling or morphogenesis develop are controlled by pluviometric variables and phyto stabilization. Moreover, the internal geodynamic of the region is related to the climatic conditions that determine the amounts of sediments aported to the Ocean basin (Kulm et al. 1977, affecting the erosion rate by subduction in the plane of contact between the tectonic plates and the composition of the magazas formed below the Andean erogene.In this paper we analyze the climatic effects in the external geodynamics, within a theoric framework that considers a morphoclimatic system as a set formed by the morphogenetic agents and processes that work the relief modeling in a territory, in function of its bioclimatic characteristics; and a morphoclimatic dominion is the spatial environment where a specific morphoclimatic system develops.First, we present the clima of the Central Andes, the factors that control its mean configuration and its main characteristics with diagrams made from the pluviometric data collected in a series of stations regularly distributed in the region. Second, we differentiate two climatic dominions, one in the Altiplano, related to Amazonia precipitations and the other at the Pacific side, associated to the anticyclonic permanency in the western cordillera. Third, we propose a subdivision of the western façade of the cordillera in altitudinal intervals or bioclimatics sections using bioindicators such as the vegetation absence or presence with altitudinal change. Fourth, we give a new division in altitudinal intervals or morphoclimatic zones, using the existence of some geoindicators, such as the endemic geomorphic units of each morphoclimatic zone.El estudio del clima es imprescindible para explicar la geodinámica externa en la vertiente del Pac

  14. Glacier Changes in the Cordillera Blanca, Peru, Derived From SPOT5 Imagery, GIS and Field- Based Measurements

    Science.gov (United States)

    Racoviteanu, A.; Arnaud, Y.; Williams, M. W.; Singh Khalsa, S.

    2007-12-01

    There is urgency in deriving an extensive dataset for deriving glacier changes within the Cordillera Blanca, Peru, in a cost-effective and timely manner. Rapid glacial retreat during the last decades in this area poses a threat for water resources, hydroelectric power and local traditions. While there is some information on decadal changes in glacier extents, there still remains a paucity of mass balance measurements and glacier parameters such as hypsometry, size distribution and termini elevations. Here we investigate decadal changes in glacier parameters for Cordillera Blanca of Peru using data from Système Probatoire d'Observation de la Terre (SPOT) sensor, an old glacier inventory from 1970 aerial photography, field-based mass balance measurements and meteorological observations. Here we focus on: constructing a geospatial glacier inventory from 2003 SPOT scenes; mass balance estimations using remote sensing and field data; frequency distribution of glacier area; changes in termini elevations; hypsometry changes over time; glacier topography (slope, aspect, length/width ratio); AAR vs. mass balance for Artesonraju and Yanamarey benchmark glaciers; precipitation and temperature trends in the region. Over the last 25 years, mean temperatures increases of 0.09 deg.C/yr were greater at lower elevation than the 0.01 deg.C/yr at higher elevations, with little change in precipitation. Comparison of the new SPOT-based glacier inventory with the 1970 inventory shows that glaciers in Cordillera Blanca retreated at a rate of 0.6% per year over the last three decades, with no significant differences in the rate of area loss between E and W side. At lower elevations there is an upward shift of glacier termini along with a decrease in glacier area. Small glaciers are losing more area than large glaciers. Based on the relationship between specific mass balance (bn) and accumulation area ratio (AAR) for the two benchmark glaciers, we predicted a steady-state equilibrium line

  15. Tectonic and lithological controls on denudation rates in the central Bolivian Andes

    Science.gov (United States)

    Kober, F.; Zeilinger, G.; Hippe, K.; Marc, O.; Lendzioch, T.; Grischott, R.; Christl, M.; Kubik, P. W.; Zola, R.

    2015-08-01

    The topographic signature of a mountain belt depends on the interplay of tectonic, climatic and erosional processes, whose relative importance changes over times, while quantifying these processes and their rates at specific times remains a challenge. The eastern Andes of central Bolivia offer a natural laboratory in which such interplay has been debated. Here, we investigate the Rio Grande catchment which crosses orthogonally the eastern Andes orogen from the Eastern Cordillera into the Subandean Zone, exhibiting a catchment relief of up to 5000 m. Despite an enhanced tectonic activity in the Subandes, local relief, mean and modal slopes and channel steepness indices are largely similar compared to the Eastern Cordillera and the intervening Interandean Zone. Nevertheless, a dataset of 57 new cosmogenic 10Be and 26Al catchment wide denudation rates from the Rio Grande catchment reveals up to one order of magnitude higher denudation rates in the Subandean Zone (mean 0.8 mm/yr) compared to the upstream physiographic regions. We infer that tectonic activity in the thrusting dominated Subandean belt causes higher denudation rates based on cumulative rock uplift investigations and due to the absence of a pronounced climate gradient. Furthermore, the lower rock strength of the Subandean sedimentary units correlates with mean slopes similar to the ones of the Eastern Cordillera and Interandean Zone, highlighting the fact, that lithology and rock strength can control high denudation rates at low slopes. Low denudation rates measured at the outlet of the Rio Grande catchment (Abapo) are interpreted to be a result of a biased cosmogenic nuclide mixing that is dominated by headwater signals from the Eastern Cordillera and the Interandean zone and limited catchment sediment connectivity in the lower river reaches. Therefore, comparisons of short- (i.e., sediment yield) and millennial denudation rates require caution when postulating tectonic and/or climatic forcing without

  16. Fossil pollen records indicate that Patagonian desertification was not solely a consequence of Andean uplift

    Science.gov (United States)

    Palazzesi, L.; Barreda, V. D.; Cuitiño, J. I.; Guler, M. V.; Tellería, M. C.; Ventura Santos, R.

    2014-03-01

    The Patagonian steppe—a massive rain-shadow on the lee side of the southern Andes—is assumed to have evolved ~15-12 Myr as a consequence of the southern Andean uplift. However, fossil evidence supporting this assumption is limited. Here we quantitatively estimate climatic conditions and plant richness for the interval ~10-6 Myr based on the study and bioclimatic analysis of terrestrially derived spore-pollen assemblages preserved in well-constrained Patagonian marine deposits. Our analyses indicate a mesothermal climate, with mean temperatures of the coldest quarter between 11.4 °C and 16.9 °C (presently ~3.5 °C) and annual precipitation rarely below 661 mm (presently ~200 mm). Rarefied richness reveals a significantly more diverse flora during the late Miocene than today at the same latitude but comparable with that approximately 2,000 km further northeast at mid-latitudes on the Brazilian coast. We infer that the Patagonian desertification was not solely a consequence of the Andean uplift as previously insinuated.

  17. Immunological properties of Andean starch films are independent of their nanometric roughness and stiffness.

    Science.gov (United States)

    Torres, F G; Troncoso, O P; Gamucci, O; Corvaglia, S; Brunetti, V; Bardi, G

    2015-04-01

    Starch is a natural material extracted from roots, seeds, stems and tubers of different plants. It can be processed as a thermoplastic to produce a variety promising products for biomedical applications, including foams, sheets and films. In the present work, we investigated the immunological properties of microfilms prepared with starches extracted from six different types of Andean potatoes and their relationship with the different film-surface features. We confirmed the biocompatibility of all the films using THP-1 human monocytes, noticing only slight decrease in cell viability in two of the tested starches. We also analyzed pro-inflammatory cytokine release and immune cell surface receptor modulation on THP-1 plated onto the films. Our data show differences in the immunological profile of the same cells cultured onto the different starch films. Furthermore, we examined whether the dissimilar stiffness or the nanometric roughness of the films might influence the immune stimulation of the THP-1 monocytes. Our results demonstrate no correlation between cultured THP-1 immune activation and surface film characteristics. We conclude that different Andean native potato starch films have specific ability to interact with cell membranes of immune cells, conceivably due to the different spatial localization of amylose and amylopectin in the diverse starches.

  18. Projected distribution shifts and protected area coverage of range-restricted Andean birds under climate change

    Directory of Open Access Journals (Sweden)

    Verónica del Rosario Avalos

    2015-07-01

    Full Text Available In this study we projected the effect of anthropogenic climate change in endemic and restricted-range Andean bird species that spread out from the center of Bolivia to southeastern Peru. We also analyzed the representation of these species in protected areas. The ensemble forecasts from niche-based models indicated that 91–100% of species may reduce their range size under full and no dispersal scenarios, including five species that are currently threatened. The large range reduction (average 63% suggests these mountain species may be threatened by climate change. The strong effects due to range species losses are predicted in the humid mountain forests of Bolivia. The representation of bird species also decreased in protected areas. Partial gap species (94–86% are expected to increase over the present (62%. This suggests climate change and other non-climate stressors should be incorporated in conservations plans for the long-term persistence of these species. This study anticipates the magnitude of shifts in the distribution of endemic birds, and represents in the study area the first exploration of the representation of range-restricted Andean birds in protected areas under climate change.

  19. Composition and diversity of High Andean in the Fauna Production Reserve Chimborazo, Ecuador

    Directory of Open Access Journals (Sweden)

    Jorge Caranqui

    2016-03-01

    Full Text Available The present study inquire the floristic diversity of 9 sampling in four plots of 1 m² of high andean in several locations in the “Reserva de Producción de Fauna Chimborazo”. For the development of this study, we used an adaptation of the method of plots “Gloria”. With coverage (% in each of the plots, Further the diversity indices and similarity with respective analysis were obtained. The data obtained reflect a diversity that can range from medium to low, believe that this is due to anthropogenic activities that have taken place in these ecosistems. With the presence mostly Calamagrostis intermedia, it could establish that the type of vegetation is herbaceous in high andean is higher percentage; is the species that is almost always present in most types of vegetation of the RPF Chimborazo and high dominance that influences the results of low floristic diversity indices was found in the analysis. As a result the most abundant family Asteraceae is well Poaceae.

  20. Direct and indirect effects of glaciers on aquatic biodiversity in high Andean peatlands

    DEFF Research Database (Denmark)

    Quenta, Estefania; Molina-Rodriguez, Jorge; Gonzales, Karina;

    2016-01-01

    The rapid melting of glacier cover is one of the most obvious impacts of climate change on alpine ecosystems and biodiversity. Our understanding of the impact of a decrease in glacier runoff on aquatic biodiversity is currently based on the 'glacier-heterogeneity-diversity' paradigm, according to...... which there is high α-diversity at intermediate levels of glacial influence due to the high degree of environmental heterogeneity caused by glacier water. This α-diversity pattern generates high levels of between-site aquatic community variation (high β diversity) and increases regional diversity (γ......-elevation peatlands (>4500 m above sea level). We sampled 200 pools from 20 peatlands along a glacier gradient in the Cordillera Real of Bolivia. We performed structural equation modeling (SEM) to analyze the potential mechanisms underlying the observed diversity patterns. Intermediate levels of glacial influence (15...

  1. Continental underthrusting and obduction during the Cretaceous closure of the Rocas Verdes rift basin, Cordillera Darwin, Patagonian Andes

    Science.gov (United States)

    Klepeis, Keith; Betka, Paul; Clarke, Geoffrey; Fanning, Mark; Hervé, Francisco; Rojas, Lisandro; Mpodozis, Constantino; Thomson, Stuart

    2010-06-01

    The Patagonian Andes record a period of Cretaceous-Neogene orogenesis that began with the compressional inversion of a Late Jurassic rift called the Rocas Verdes basin. Detrital zircon ages from sediment that filled the southern part of the basin provide a maximum depositional age of ˜148 Ma, suggesting that the basin opened approximately simultaneously along its length during the Late Jurassic. Structural data and U-Pb isotopic ages on zircon from granite plutons near the Beagle Channel (55°S) show that basin inversion involved two stages of shortening separated by tens of millions of years. An initial stage created a small (˜60 km wide) thrust wedge that placed the basaltic floor of the Rocas Verdes basin on top of adjacent continental crust prior to ˜86 Ma. Structures and metamorphic mineral assemblages preserved in an exhumed middle to lower crustal shear zone in Cordillera Darwin suggest that this obduction was accompanied by south directed subduction of the basaltic crust and underthrusting of continental crust to depths of ˜35 km beneath a coeval volcanic arc. A subsequent stage of out-of-sequence thrusting, culminating in the Paleogene, shortened basement and Upper Jurassic igneous rock in the internal part of the belt by at least ˜50 km, forming a bivergent thrust wedge. This latter period coincided with the exhumation of rocks in Cordillera Darwin and expansion of the fold-thrust belt into the Magallanes foreland basin. This orogen provides an important example of how orogenesis initiated and led to continental underthrusting and obduction of basaltic crust during closure of a quasi-oceanic rift basin.

  2. Recalibration of the yellow Rhizocarpon growth curve in the Cordillera Blanca (Peru) and implications for LIA chronology

    Science.gov (United States)

    Jomelli, V.; Grancher, D.; Brunstein, D.; Solomina, O.

    2008-01-01

    A new lichen dating method and new moraine observations enabled us to improve the chronology of glacier advances in the Cordillera Blanca (Peru) during the Little Ice Age (LIA). Our results reveal that an early LIA glacial advance occurred around AD 1330 ± 29. However, a second major glacial advance at the beginning of the 17th century overlapped the earlier stage for most glaciers. Hence, this second glacial stage, dated from AD 1630 ± 27, is considered as the LIA maximum glacial advance in the Cordillera Blanca. During the 17th-18th centuries, at least three glacial advances were recorded synchronously for the different glaciers (AD 1670 ± 24, 1730 ± 21, and 1760 ± 19). The moraines corresponding to the two first stages are close to the one in 1630 suggesting a slow recession of about 18% in the total length of the glacier. From the LIA maximum extent to the beginning of the 20th century, the 24 glaciers have retreated a distance of about 1000 m, corresponding to a reduction of 30% in their length. This rate is comparable to that observed during the 20th century. Estimates of palaeo-Equilibrium Line Altitudes show an increase in altitude of about 100 m from the LIA maximum glacial extension at the beginning of the 17th century to the beginning of the 20th century. Because long time series are not available for precipitation and temperature, this glacial retreat is difficult to explain by past climate changes. However, there is a fair correspondence between changes in glacier length and the δ18O recorded in the Quelccaya ice core at a century timescale. Our current knowledge of tropical glaciers and isotope variations leads us to suggest that this common tropical signal reflects a change from a wet LIA to the drier conditions of today. Finally, a remarkable synchronicity is observed with glacial variations in Bolivia, suggesting a common regional climatic pattern during the LIA.

  3. Coarse Grain Progradation in a Foreland basin: Application of Detrital Zircon Double Dating to Cenozoic Stratigraphy, Eastern Cordillera, Colombia.

    Science.gov (United States)

    Odoh, S.; Saylor, J. E.; Higuera-Diaz, C.; Lapen, T. J.; Copeland, P.

    2015-12-01

    Progradation of coarse clastic material into distal foreland basins has been attributed to both 1) enhanced sediment production during rapid tectonic exhumation and 2) sediment reworking during tectonic quiescence. The Floresta and Medina basins in the Eastern Cordillera record deposition of alternating coarse- and fine-grained clastic strata in medial and distal (respectively) Cenozoic foreland basins. The Medina Basin records the continued eastward progradation of the deformation front in the Neogene. We use detrital zircon U-Pb (ZPb) and (U-Th)/He (ZHe) analyses from the Paleogene Floresta Basin and the entire Cenozoic Medina Basin record to evaluate the effects of episodic thrust-belt exhumation and wide-spread deposition of coarse-grained sediments in the adjacent foreland basin. Both ZPb and ZHe systems are applied to individual grains (double dating) to constrain source area and up-section variations in exhumation rates. Changes in exhumation rate or introduction of new sediment sources are recorded as changes in lag time (ZHe age - depositional age). Analysis of 6 samples from the Floresta Basin shows a decrease in lag time during deposition of the coarse-grained middle Eocene Picacho Formation and upper Paleocene Socha Sandstone suggesting that Paleogene deposition of coarse-grained intervals in this medial location corresponds to an increase in exhumation rate. However, initial results from the Medina basin are less clear as there is evidence for Paleocene volcanic input but no clear evidence for thrust-belt related sediment until the Oligocene-early Miocene. We interpret the evidence for different sediment sources for Eocene strata in the axial Eastern Cordillera (Floresta) versus the Eastern foothills (Medina) as indicative of separation of these two regions by an emergent forebulge. Exhumation rate and granularity appear to be inversely correlated in post-Oligocene strata, though confirmation of initial interpretations awaits larger samples sizes

  4. Faults delineation and stress orientations from the microseismicity analysis of the Servita Fault System, Colombian Eastern Cordillera

    Science.gov (United States)

    Pedraza García, P.; Dimate, C.

    2014-12-01

    The Servita Fault System (SFS) is located in the eastern foothills of the Colombian Andes Eastern Cordillera. This region is a structurally complex area with high seismogenic potential. The refined analysis of the microseismicity registered by a portable seismic network allows to delineate the main active faults and to estimate the direction of the regional tectonic stress. We analyzed a high quality microearthquake data-set consisting of 890 events occurred during 2011-2012 with a local magnitude range between 0.1 and 3.2 and depths up to 40km. The refined locations of the events show a general SW-NE trend that follows the trace of the SFS. Selected focal mechanisms show predominantly right-lateral strike slip motion. Results show that seismicity to the northern sector of the SFS is distributed in two groups, one on the axial zone of the cordillera and the other on the eastern flank. Most of the microearthquakes are concentrated in the rupture zone of Quetame earthquake (2008, Mw=5.9). Alignment of hypocenters along the eastern flank and some focal mechanisms suggest a fault plane dipping to the west, which is interpreted as the Servita Fault plane. Southwards of the Rio Negro, seismicity decreases and loses continuity. This feature coincides with the trace of the WSW-ENE Rio Blanco Fault which possibly segments the Servita Fault. Southwards, seismicity is spread over a wider area and exhibits deeper hypocenters compared to the northern sector. Hypocenter distribution and focal mechanisms in this sector suggest two planes dipping to the west which we interpret as segments of the Algeciras Fault and another plane (northwards) steeply dipping to the southeast interpreted as the fault plane of the Altamira Fault.

  5. The volcanism of the western part of the Los Frailes Meseta (Bolivia): a representative example of the Andean volcanism since the Upper Oligocene; Le volcanisme de la bordure occidentale de la Meseta de Los Frailes (Bolivie): un jalon representatif du volcanisme andin depuis l`Oligocene superieur

    Energy Technology Data Exchange (ETDEWEB)

    Leroy, L. [Nancy-1 Univ., 54 (France); Jimenez, N.

    1996-12-31

    The Los Frailes Meseta (Bolivia) is one of the large tertiary ignimbritic fields of the inner volcanic arc from Central Andes (Central Volcanic Zone. CVZ), in contact zone between the Altiplano to the west and the Eastern Cordillera to the east. Field observations and mineralogical and geochemical studies (major and trace elements) lead to distinguish two types of volcanism in the western border to the Meseta. During the Middle Miocene and Pliocene, the volcanic activity can be subdivided into three pyroclastic emission cycles, the Larco, Coroma and Pliocene ignimbrites, the first two being separated by the Quechua 2 orogeny. All these ignimbrites are very similar and correspond to peraluminous rhyolites to rhyodacites. In the studies area, the Coroma cycle is the only one where an ignimbrite-less evolved resurgent dome association can be observed. Beside these ignimbrites, isolated small lava flows and domes overlay and/or intrude all the other formations. They are meta-aluminous lavas with a shoshonitic affinity. A quaternary age can be attributed to his second volcanism. These two volcanic types are well-known in the CVZ and are related to the different deformation stages, either compressional or extensional, which occur alternately in the Cordillera since 26 Ma. (authors). 61 refs., 12 figs., 3 tabs.

  6. Landscape genetics, historical isolation and cross-Andean gene flow in the wax palm, Ceroxylon echinulatum (Arecaceae)

    DEFF Research Database (Denmark)

    Trénel, P.; Hansen, Michael Møller; Nordmand, S.;

    2008-01-01

    and landscape genetics of the Andean wax palm Ceroxylon echinulatum (Arecaceae) that occurs in two narrow bands of montane forests on each side of the Andes in Ecuador and northeastern Peru. First, we tested the hypothesis of C. echinulatum being a geographic cline species crossing the Andes in the Amotape...

  7. Phenolic compound contents and antioxidant activity in plants with nutritional and/or medicinal properties form the Peruvian Andean region

    NARCIS (Netherlands)

    Chirinos, R.; Pedreschi Plasencia, R.P.; Rogez, H.

    2013-01-01

    Total phenolic compounds (TPC) and antioxidant activities using different assays (DPPH, ABTS and ORAC) in fruits, grains, leaves, seeds, roots and tubers from 27 different Peruvian Andean plants used in folk medicine or/and as food by the native population were evaluated in order to use these as nat

  8. Contextual Analysis of the Decision To Adopt a Regional Satellite System: The Case of the Andean CONDOR.

    Science.gov (United States)

    Ferreira, Leonardo; Mody, Bella

    Acknowledging the importance of communications in economic development, this paper discusses the rationale behind the decision of the Andean Pact nations of Bolivia, Colombia, Ecuador, Peru, and Venezuela to develop a regional satellite communication system to be known as CONDOR. The application of contextual theorizing to the decision-making…

  9. Tectonic and paleoenvironmental evolution of Mesozoic sedimentary basins along the Andean foothills of Argentina (32°-54°S)

    Science.gov (United States)

    Franzese, Juan; Spalletti, Luis; Pérez, Irene Gómez; Macdonald, David

    2003-05-01

    Chronoenvironmental and tectonic charts are presented for Mesozoic basins located along the Andean foothills of the South American plate. On the basis of the main tectonic events, pre-Andean basins, break-up-related basins, extensional back-arc basins, and Andean foreland basins are recognized. The pre-Andean basins were formed by continental extension and strike-slip movement before the development of the Mesozoic-Cenozoic Andean magmatic arc. Upper Permian to Middle Triassic extension along Palaeozoic terrane sutures resulted in rifting, bimodal magmatism (Choiyoi group), and continental deposition (Cuyo basin). From the Late Triassic to the Early Jurassic, continental extension related to the collapse of the Gondwana orogen initiated a series of long, narrow half-grabens that filled with continental volcaniclastic deposits. These depocenters were later integrated into the Neuquén basin. Coeval development of the shallow marine Pampa de Agnia basin (42-44°S) is related to short-lived extension, probably driven by dextral displacement along major strike-slip faults (e.g. the Gastre fault system). Widespread extension related to the Gondwana breakup (180-165 Ma) and the opening of the Weddell Sea reached the western margin of the South American plate. As a result, wide areas of Patagonia were affected by intraplate volcanism (Chon Aike province), and early rifting occurred in the Magallanes basin. The Andean magmatic arc was almost fully developed by Late Jurassic times. A transgressive stage with starvation and anoxia characterized the Neuquén basin. In western Patagonia, back-arc and intra-arc extension produced the opening of several grabens associated with explosive volcanism and lava flows (e.g. Rı´o Mayo, El Quemado). To the south, a deep marginal basin floored by oceanic crust (Rocas Verdes) developed along the back-arc axis. In mid-to late Cretaceous times, Andean compressional tectonics related to South Atlantic spreading caused the inversion of

  10. Nazca-South America interactions and the late Eocene-late Oligocene flat-slab episode in the central Andes

    Science.gov (United States)

    O'Driscoll, Leland J.; Richards, Mark A.; Humphreys, Eugene D.

    2012-04-01

    The most prominent features of the Andean range are the Altiplano and Puna plateaus, which were constructed by crustal shortening and uplift over the past ˜45 Myr. The early construction of these plateaus may have controlled subsequent growth of the orogen. Proposed models have suggested that an abrupt acceleration in relative motion between the Nazca plate and the South American plate at ˜30 Ma may have led to compression of the continent. However, the major plate motion change occurred at 25-23 Ma, and paleomagnetic rotations and crustal shortening of the Andean forearc require that the Arica Bend formed prior to about 25 Ma. Inferred history of flat-slab subduction along the Altiplano section of the Andean margin and the structure of the adjacent South American cratonic shield combine to suggest an alternate scenario, based partly upon geodynamic models of oceanic-continental plate interactions in subduction zones. We propose that central Andean tectonism may have been controlled by two distinct regimes of subduction: (1) oblique subduction along the central Andean margin during the late Eocene and Oligocene accompanied by downdip alignment with the center of the Amazonian Shield (flat-slab activity in this phase of orogenesis may have been caused by a combination of cratonic root enhanced tectonics and oceanic plateau subduction) and (2) an abrupt transition to trench-normal subduction after ˜25 Ma toward the more distal São Francisco Craton was accompanied by a return to normal angle subduction. Similar interactions are hypothesized to have occurred during the Laramide Orogeny in western North America.

  11. Paleomagnetism and magnetic fabric of the Eastern Cordillera of Colombia: Evidence for oblique convergence and non-rotational reactivation of a Mesozoic intra-continental rift

    Science.gov (United States)

    Jiménez Díaz, G.; Speranza, F.; Faccenna, C.; Bayona, G.; Mora, A.

    2012-12-01

    The Eastern Cordillera of Colombia (EC) is a double-verging mountain system inverting a Mesozoic rift, and bounded by major reverse faults that locally involve crystalline and metamorphic Precambrian-Lower Paleozoic basement rocks, as well as Upper Paleozoic-Cenozoic sedimentary and volcanic sequences. In map view the EC is a curved mountain belt with a regional structural strike that ranges from NNE in the southern part to NNW in the northern part. The origin of its curvature has not been studied or discussed so far. We report on an extensive paleomagnetic and anisotropy of magnetic susceptibility (AMS) investigation of the EC, in order to address to test its non-rotational vs. oroclinal nature. Fifty-eight sites were gathered from Cretaceous to Miocene marine and continental strata, both from the southern and northern parts of the EC; additionally, we examined the southern Maracaibo plate, at the junction between the Santander Massif and the Merida Andes of Colombia (Cucuta zone). Twenty-three sites reveal no rotation of the EC range with respect to stable South America. In contrast, a 35°±9° clockwise rotation is documented in four post-Miocene magnetically overprinted sites from the Cucuta zone. Magnetic lineations from AMS analysis do not trend parallel to the chain, but are oblique to the main strike of the orogenic belt. By also considering GPS evidence of a ~1 cm/yr ENE displacement of central-western Colombia accommodated by the EC, we suggest that the late Miocene-recent deformation occurred by a ENE oblique convergence reactivating a NNE rift zone. Our data show that the EC is a non-rotational chain, and that the locations of the Mesozoic rift and the mountain chain roughly correspond. One possible solution is that the oblique shortening is partitioned in pure dip-slip shear characterizing thick-skinned frontal thrust sheets (well-known along both chain fronts), and by range-parallel right-lateral strike-slip fault(s), which have not been identified

  12. Detrital zircon SHRIMP U-Pb age study of the Cordillera Darwin Metamorphic Complex of Tierra del Fuego : sedimentary sources and implications for the evolution of the Pacific margin of Gondwana

    OpenAIRE

    Herve, F.; Fanning, C.M.; Pankhurst, R.J.; Mpodozis, C.; Klepeis, K.; Calderon, M.; S. N. Thomson

    2010-01-01

    The Cordillera Darwin Metamorphic Complex in the southernmost Andes includes a basement of probable Palaeozoic age, a mid-Jurassic and younger volcano-sedimentary cover, and a suite of Jurassic granites, all of which were jointly metamorphosed during the Cretaceous. Detrital zircon ages presented here show that some of the amphibolite-facies metamorphic rocks previously mapped as basement have a Jurassic protolith. Overall the detrital zircon age patterns for samples of the Cordillera Darwin ...

  13. Fajas oblicuas de deformación neotectónica en Precordillera y Cordillera Frontal (31° 30´ - 33° 30´ LS: controles paleotectónicos

    Directory of Open Access Journals (Sweden)

    J.M. Cortés

    2006-12-01

    Full Text Available La Precordillera Sur y las Cerrilladas Pedemontanas de Mendoza, son dos unidades morfotectónicas principales en la vertiente oriental de los Andes centrales, a los 31º30' - 33º30' de latitud sur. Allí, dos cinturones de deformación transpresiva y orientación noroeste, denominados fajas Barreal-Las Peñas y Río Mendoza-Tupungato, se desarrollaron como consecuencia de la gradual somerización de la placa de Nazca en los últimos 20 Ma. Su orientación y compleja geometría estructural resulta de la interferencia de la deformación andina tardío-cenozoica con la estructura de orientación noroeste del rift triásico de la cuenca Cuyana y antiguas zonas de sutura colisional de edad paleozoica. Este trabajo demuestra que los rasgos paleotectónicos del substrato triásico-paleozoico de la Precordillera Sur y del margen oriental de la Cordillera Frontal controlan la configuración morfotectónica y la distribución y reactivación de gran parte de la estructura neotectónica del margen andino a estas latitudes.

  14. Constuccion social de comuninad y migración en Usibamba : un estudio sobre el impacto de los procesos de globalización en los Andes centrales del Perú

    NARCIS (Netherlands)

    Gilvonio Perez, J.M.

    2009-01-01

    The research for the thesis was conducted in the village of Usibamba, located in a high-Andean area called Alto Cunas east from the Mantaro Valley in the Peruvian Central Andes. Special attention was paid to the institutional context and the everyday life conditions in which the social construction

  15. Analysis of the drought recovery of Andosols on southern Ecuadorian Andean páramos

    Science.gov (United States)

    Iñiguez, Vicente; Morales, Oscar; Cisneros, Felipe; Bauwens, Willy; Wyseure, Guido

    2016-06-01

    The Neotropical Andean grasslands above 3500 m a.s.l., known as páramo, offer remarkable ecological services for the Andean region. The most important of these is the water supply of excellent quality to many cities and villages in the inter-Andean valleys and along the coast. The páramo ecosystem and especially its soils are under constant and increased threat by human activities and climate change. In this study, the recovery speed of the páramo soils after drought periods are analysed. The observation period includes the droughts of 2009, 2010, 2011, and 2012 together with intermediate wet periods. Two experimental catchments - one with and one without páramo - were investigated. The Probability Distributed Moisture (PDM) model was calibrated and validated in both catchments. Drought periods and its characteristics were identified and quantified by a threshold level approach and complemented by means of a drought propagation analysis. At the plot scale in the páramo region, the soil water content measured by time domain reflectometry (TDR) probes dropped from a normal value of about 0.84 to ˜ 0.60 cm3 cm-3, while the recovery time was 2-3 months. This did not occur at lower altitudes (Cumbe) where the soils are mineral. Although the soil moisture depletion observed in these soils was similar to that of the Andosols (27 %), decreasing from a normal value of about 0.54 to ˜ 0.39 cm3 cm-3, the recovery was much slower and took about 8 months for the drought in 2010. At the catchment scale, however, the soil water storage simulated by the PDM model and the drought analysis was not as pronounced. Soil moisture droughts occurred mainly in the dry season in both catchments. The deficit for all cases is small and progressively reduced during the wet season. Vegetation stress periods correspond mainly to the months of September, October and November, which coincides with the dry season. The maximum number of consecutive dry days were reached during the drought of

  16. Deformation, deposition, and surface uplift in the hinterland of the Central Andes, Bolivia

    Science.gov (United States)

    Leier, A.; McQuarrie, N.; Garzione, C. N.; Eiler, J. M.

    2011-12-01

    Paleoelevation histories from mountain belts like the Central Andes of Bolivia provide important constraints on the timing and geodynamic mechanisms associated with surface uplift. New stable isotope data from paleosol carbonate nodules in the Altiplano and Eastern Cordillera of the Central Andes of Bolivia indicate a previously undocumented episode of surface uplift occurred in the region between ca. 24 and 17 Ma. Oxygen isotope and clumped-isotope thermometry values from paleosol carbonate in strata >24 Ma suggest paleoelevations as low as sea-level. Paleosol carbonate in strata ca. 17 Ma have oxygen isotope and clumped-isotope thermometry values, which using modern lapse rates, indicate an increase in elevation of approximately 3 km. Relatively undeformed Oligocene and Miocene strata overlap faulted Paleozoic rocks of the Bolivian Eastern Cordillera, indicating deposition and surface uplift post-dated and was decoupled from upper crustal deformation. Together, geological data from the area record an initial period of deformation and exhumation, a subsequent period of sediment deposition and overlap, and then an episode of surface uplift that was not accompanied by upper crustal deformation. We propose accommodation for the Oligocene-Miocene strata was associated with mantle and lowermost crustal processes, and the subsequent increase in surface elevation was an isostatic response to removal of dense material through delamination or drip. Combined with existing data sets in the Central Andes, these new data suggest multiple, regionally-variable, and diachronous periods of surface uplift occurred within the Central Andes during the Cenozoic Era.

  17. Description of a New Species of the Andean Butterfly Genus Forsterinaria Gray (Lepidoptera: Nymphalidae) with Considerations on an Apparently New Structure in Male Genitalia.

    Science.gov (United States)

    Zubek, A; Pyrcz, T W; Boyer, P

    2014-02-01

    The butterfly genus Forsterinaria Gray is the only strictly montane representative of the diverse Neotropical subtribe Euptychiina (Nymphalidae, Satyrinae), with 24 described species. Recent research in some of the most isolated and highly diverse Andean regions, such as central Peru, show that its total species richness is still underestimated. An example is the new species described here, Forsterinaria emo n. sp., which is particularly interesting because of an unusual structure discovered in its male genitalia which consists of a bunch of bristle-like processes, composing a fringe-like formation on the dorsum of the tegumen. No similar, homologous structure was found in any congener, nor indeed, in any species of diurnal Lepidoptera. Scanning electron microscope studies revealed that the microstructure of the processes resembles a membrane lining the tegumen. Its function is unknown but two hypotheses are discussed based on a comparative study with other genital structures of butterflies. We argue that it may help stabilizing the partners in the process of mating or it may serve as a 'mating plug', preventing the female from multiple copulations.

  18. Pertinent spatio-temporal scale of observation to understand suspended sediment yield control factors in the Andean region: the case of the Santa River (Peru)

    Science.gov (United States)

    Morera, S. B.; Condom, T.; Vauchel, P.; Guyot, J.-L.; Galvez, C.; Crave, A.

    2013-11-01

    Hydro-sedimentology development is a great challenge in Peru due to limited data as well as sparse and confidential information. This study aimed to quantify and to understand the suspended sediment yield from the west-central Andes Mountains and to identify the main erosion-control factors and their relevance. The Tablachaca River (3132 km2) and the Santa River (6815 km2), located in two adjacent Andes catchments, showed similar statistical daily rainfall and discharge variability but large differences in specific suspended-sediment yield (SSY). In order to investigate the main erosion factors, daily water discharge and suspended sediment concentration (SSC) datasets of the Santa and Tablachaca rivers were analysed. Mining activity in specific lithologies was identified as the major factor that controls the high SSY of the Tablachaca (2204 t km2 yr-1), which is four times greater than the Santa's SSY. These results show that the analysis of control factors of regional SSY at the Andes scale should be done carefully. Indeed, spatial data at kilometric scale and also daily water discharge and SSC time series are needed to define the main erosion factors along the entire Andean range.

  19. Ailinella mirabilis gen. n., sp. n. (eucestoda: pseudophyllidea) from Galaxias maculatus (Pisces: Galaxiidae) in the Andean-Patagonian region of Argentina.

    Science.gov (United States)

    de Pertierra, Alicia A Gil; Semenas, Liliana G

    2006-12-01

    Ailinella gen. n. (Pseudophyllidea: Triaenophoridae) is proposed to accommodate Ailinella mirabilis sp. n. from Galaxias maculatus (Jenyns, 1842), a freshwater fish inhabiting the Andean lakes in Argentinean Patagonia. Ailinella belongs to the Triaenophoridae because it has a marginal genital pore, a follicular vitelline gland, and a ventral uterine pore. The new genus can be distinguished from other triaenophorids by the following combination of characters: a small body size, a low number of proglottides, which are longer than wide, a truncated pyramidal to globular scolex, a rectangular apical disc, presence of the neck, lack of internal longitudinal musculature separating the cortex from the medulla, testes distributed in one central field surrounding the ovary laterally and posteriorly, the vagina predominantly anterior to the cirrus sac, vitelline follicles circum-medullary, the genital pores post-equatorial, a saccate uterus, and operculate eggs. Blade-like spiniform microtriches were present on all tegument surfaces, and tumuli on all surfaces of the scolex and the anterior surface of the neck. Microtriches were characterized according to their size and density, and tumuli according to their size, inter-tumulus distance and density. Ailinella mirabilis is the first cestode described from G. maculatus and the second triaenophorid species recorded from a South American freshwater fish. PMID:17256203

  20. Mercury Contamination in an Indicator Fish Species from Andean Amazonian Rivers Affected by Petroleum Extraction.

    Science.gov (United States)

    Webb, Jena; Coomes, Oliver T; Mainville, Nicolas; Mergler, Donna

    2015-09-01

    Elevated mercury (Hg) concentrations in fish from Amazonia have been associated with gold-mining, hydroelectric dams and deforestation but few studies consider the role of petroleum extraction. Hg levels were determined in fish samples collected in three river basins in Ecuador and Peru with contrasting petroleum exploitation and land-use characteristics. The non-migratory, piscivorous species, Hoplias malabaricus, was used as a bioindicator. The rate of Hg increase with body weight for this species was significantly higher on the Corrientes River, near the site of a recent oil spill, than on the other two rivers. In the absence of substantial deforestation and other anthropogenic sources in the Corrientes River basin, this finding suggests that oil contamination in Andean Amazonia may have a significant impact on Hg levels in fish.

  1. History aspects and ecology of the biodiversity nor Andean and Amazonic

    International Nuclear Information System (INIS)

    The mega-biodiversity of the neotropics is type result of the geological and environmental history. A considerable biodiversity, higher than at present, existed in the Miocene in the low-elevation tropics. The progressive upheaval of the Andes created new life zones that were populated by adaptive evolution and immigration from the austral-Antarctic and laurasiatic-holartic regions. The cooling of the earth during the Neogene and the glacial- interglacial cycles of the quaternary, and the consonant changes of temperature and rainfall, in combination with the topography, had a profound effect on vegetation, flora and fauna, the distribution of species and endemism, both in the low tropical area and in the Andean zones. Presently there is a positive relation of species-density with temperature (altitude) and with rainfall, and partly with relative humidity

  2. Spatial modeling of cutaneous leishmaniasis in the Andean region of Colombia.

    Science.gov (United States)

    Pérez-Flórez, Mauricio; Ocampo, Clara Beatriz; Valderrama-Ardila, Carlos; Alexander, Neal

    2016-06-27

    The objective of this research was to identify environmental risk factors for cutaneous leishmaniasis (CL) in Colombia and map high-risk municipalities. The study area was the Colombian Andean region, comprising 715 rural and urban municipalities. We used 10 years of CL surveillance: 2000-2009. We used spatial-temporal analysis - conditional autoregressive Poisson random effects modelling - in a Bayesian framework to model the dependence of municipality-level incidence on land use, climate, elevation and population density. Bivariable spatial analysis identified rainforests, forests and secondary vegetation, temperature, and annual precipitation as positively associated with CL incidence. By contrast, livestock agroecosystems and temperature seasonality were negatively associated. Multivariable analysis identified land use - rainforests and agro-livestock - and climate - temperature, rainfall and temperature seasonality - as best predictors of CL. We conclude that climate and land use can be used to identify areas at high risk of CL and that this approach is potentially applicable elsewhere in Latin America. PMID:27355214

  3. Traditional use of the Andean flicker (Colaptes rupicola as a galactagogue in the Peruvian Andes

    Directory of Open Access Journals (Sweden)

    Froemming Steve

    2006-05-01

    Full Text Available Abstract This paper explores the use of the dried meat and feathers of the Andean Flicker (Colaptes rupicola to increase the milk supply of nursing women and domestic animals in the Andes. The treatment is of preColumbian origin, but continues to be used in some areas, including the village in the southern Peruvian highlands where I do ethnographic research. I explore the factors giving rise to and sustaining the practice, relate it to other galactagogues used in the Andes and to the use of birds in ethnomedical and ethnoveterinary treatments in general, and situate it within the general tendency in the Andes and elsewhere to replicate human relations in the treatment of valuable livestock. The bird's use as a galactagogue appears to be motivated by both metaphorical associations and its perceived efficacy, and conceptually blends human and animal healthcare domains.

  4. The Sabethines of Northern Andean Coffee-Growing Regions of Colombia.

    Science.gov (United States)

    Suaza-Vasco, Juan; López-Rubio, Andrés; Galeano, Juan; Uribe, Sandra; Vélez, Iván; Porter, Charles

    2015-06-01

    Sampling for sabethine mosquitoes occurred intermittently from September 2007 to April 2013 in 17 municipalities, located in 5 departments (divisions) in the northern Andean coffee-growing regions of Colombia. Of the 9 genera within the Sabethini tribe known to occur in the Neotropical region, 6 were encountered including 15 species: Jonhbelkinia ulopus, Limatus durhamii, Sabethes ignotus, Sa. luxodens, Sa. undosus, Shannoniana fluviatilis, Trichoprosopon compressum, Tr. digitatum, Tr. evansae, Tr. pallidiventer s.l., Tr. pallidiventer s.s., Wyeomyia arthrostigma, Wy. oblita, Wy. ulocoma, and Wy. undulata. The species Sa. luxodens and Wy. undulata constitute new records for Colombia. These records broaden the knowledge of this important group that includes some important species related to the arbovirus transmission. Records are from the northern Colombian Andes, a region noted for coffee cultivation and ecotourism. PMID:26181687

  5. An Environmental Watch System for the Andean countries: El Observatorio Andino

    CERN Document Server

    Muñoz, Ángel G; Velasquez, Ramon; Monterrey, Luis; Leon, Gloria; Ruiz, Franklyn; Recalde, Cristina; Cadena, Jaime; Mejia, Raul; Paredes, Marcos; Bazo, Juan; Reyes, Carmen; Carrasco, Gualberto; Castellon, Yaruska; Villarroel, Claudia; Quintana, Juan; Urdaneta, Avel

    2010-01-01

    An experimental Environmental Watch System, the so-called Observatorio Andino-OA (Observatorio Andino), has been implemented in Venezuela, Colombia, Ecuador, Peru, Bolivia, and Chile over the past two years. The OA is a collaborative and regional network that aims to monitor several environmental variables and develop accurate forecasts based on different scientific tools. Its overall goal is to improve risk assessments, set up Early Warning Systems, support decision-making processes, and provide easily- and intuitively-understandable spatial maps to end-users. The initiative works under the scientific and logistic coordination of the Centro de Modelado Cient\\'ifico (CMC) at Zulia University, Venezuela, and the Centro Internacional para la Investigaci\\'on del Fen\\'omeno 'El Ni\\~no' (CIIFEN), and is operated at a local level by the National Weather Services (NWSs) of the aforementioned six Andean nations. The OA provides several freely-available model outputs including meteorological and hydrological forecasts...

  6. Invertebrate metacommunity structure and dynamics in an andean glacial stream network facing climate change

    DEFF Research Database (Denmark)

    Cauvy-Fraunié, Sophie; Espinosa, Rodrigo; Andino, Patricio;

    2015-01-01

    theory as a conceptual framework to better understand how river network structure influences the spatial organization of aquatic communities in glacierized catchments. At 51 stream sites in an Andean glacierized catchment (Ecuador), we sampled benthic macroinvertebrates, measured physico......-chemical and food resource conditions, and calculated geographical, altitudinal and glaciality distances among all sites. Using partial redundancy analysis, we partitioned community variation to evaluate the relative strength of environmental conditions (e.g., glaciality, food resource) vs. spatial processes (e.......g., overland, watercourse, and downstream directional dispersal) in organizing the aquatic metacommunity. Results revealed that both environmental and spatial variables significantly explained community variation among sites. Among all environmental variables, the glacial influence component best explained...

  7. Temporal patterns of diversification in Andean Eois, a species-rich clade of moths (Lepidoptera, Geometridae).

    Science.gov (United States)

    Strutzenberger, P; Fiedler, K

    2011-04-01

    The timing of the origin of present day Neotropical animal diversity is still a matter of debate. For a long time, a preponderance of glacial (i.e. Pleistocene) radiations has been proposed. However, recent data from molecular clock studies indicate a preglacial origin for most of the examined taxa. We performed a fossil-calibrated molecular dating analysis of the genus Eois, which is a major component of one of the world's most diverse assemblages of herbivorous insects. We found that diversification of Eois took place in the Miocene following a pattern best explained by density-dependent diversification. A strong slowdown of diversification towards the present was detected. Diversification of Eois does overlap with increased Andean uplift and diversification of the most commonly used host plant genus Piper. These findings match the patterns found for the majority of Neotropical tetrapods and for three other unrelated, ecologically different lepidopteran genera.

  8. The CERESIS earthquake catalogue and database of the Andean Region: background, characteristics and examples of use

    Directory of Open Access Journals (Sweden)

    L. R. Valverde

    2004-06-01

    Full Text Available The history of earthquakes in South America starts with the coming of the Spanish and Portuguese «conquistadores» at the beginning of the 16th century. Their chronicles, and those of local historians, are the only source of earthquake information for the following 400 years. The creation of the Regional Centre for Seismology for South America (CERESIS was a major factor for homogenous regional progress, in that CERESIS promoted the implementation of the first unified earthquake catalogue and database for the whole Andean Region. This paper reviews basic information about the intensity database and the focal parameter catalogues proposed by CERESIS in 1985. Further macroseismic data available from the CERESIS database (earthquakes with I0 = 8 are used to obtain preliminary results for the earthquake source parameters of selected South American historical events. The case of the Great Earthquake of the Venezuelan Andes, 29 April 1894, is presented in some detail.

  9. Mercury Contamination in an Indicator Fish Species from Andean Amazonian Rivers Affected by Petroleum Extraction.

    Science.gov (United States)

    Webb, Jena; Coomes, Oliver T; Mainville, Nicolas; Mergler, Donna

    2015-09-01

    Elevated mercury (Hg) concentrations in fish from Amazonia have been associated with gold-mining, hydroelectric dams and deforestation but few studies consider the role of petroleum extraction. Hg levels were determined in fish samples collected in three river basins in Ecuador and Peru with contrasting petroleum exploitation and land-use characteristics. The non-migratory, piscivorous species, Hoplias malabaricus, was used as a bioindicator. The rate of Hg increase with body weight for this species was significantly higher on the Corrientes River, near the site of a recent oil spill, than on the other two rivers. In the absence of substantial deforestation and other anthropogenic sources in the Corrientes River basin, this finding suggests that oil contamination in Andean Amazonia may have a significant impact on Hg levels in fish. PMID:26205230

  10. Temporal patterns of diversification in Andean Eois, a species-rich clade of moths (Lepidoptera, Geometridae).

    Science.gov (United States)

    Strutzenberger, P; Fiedler, K

    2011-04-01

    The timing of the origin of present day Neotropical animal diversity is still a matter of debate. For a long time, a preponderance of glacial (i.e. Pleistocene) radiations has been proposed. However, recent data from molecular clock studies indicate a preglacial origin for most of the examined taxa. We performed a fossil-calibrated molecular dating analysis of the genus Eois, which is a major component of one of the world's most diverse assemblages of herbivorous insects. We found that diversification of Eois took place in the Miocene following a pattern best explained by density-dependent diversification. A strong slowdown of diversification towards the present was detected. Diversification of Eois does overlap with increased Andean uplift and diversification of the most commonly used host plant genus Piper. These findings match the patterns found for the majority of Neotropical tetrapods and for three other unrelated, ecologically different lepidopteran genera. PMID:21401769

  11. Feeding Ecology of Two Plecopterans in Low Order Andean-Patagonian Streams

    Science.gov (United States)

    Albariño, Ricardo J.; Díaz Villanueva, Verónica

    2006-05-01

    Feeding plasticity of the Andean plecopteran Klapopteryx kuscheli and Notoperla archiplatae larvae was assessed through a field experiment using enclosures. K. kuscheli has previously been described as a shredder and N. archiplatae as a scraper. Further information on gut contents from different populations supported those results. In the experiment, larvae of both species were exposed to contrasting food items: leaf litter and periphyton. Consumption, growth and the efficiency of food conversion were measured. K. kuscheli was able to feed on periphyton, though it did not grow. N. archiplatae failed to feed on leaf litter. While K. kuscheli might be considered a facultative shredder, N. archiplatae functions as a specialist scraper. The natural distribution and seasonal abundance in two small streams showed contrasting habitat use of both species. N. archiplatae inhabited high velocity runs and riffles underneath large substrates while K. kuscheli presented a higher habitat plasticity. Implications of those results for ecosystem function are discussed.

  12. Infection of Myxobolus galaxii (Myxozoa) in Galaxias maculatus (Osmeriformes: Galaxiidae) from northwestern Patagonian Andean lakes (Argentina).

    Science.gov (United States)

    Flores, Verónica; Viozzi, Gustavo

    2007-04-01

    The infection of Myxobolus galaxii Szidat, 1953, from the musculature and abdominal organs of northwestern Patagonian Galaxias maculatus is described. Plasmodia are histozoic and intercellular. Spores are pyriform in valvar view and biconvex in sutural view, with 4-9 edge notches in the sutural line, varying in shape within the same plasmodium. Myxobolus galaxii was detected in fish from 7 of 17 Andean Patagonian lakes, with prevalences ranging between 2 and 17%. A repeating pattern of summer increment in prevalence was observed, which could be explained by the ontogenetic migratory movements of the fish in Lake Gutiérrez. Also, accumulation of plasmodia through the life span of fish was detected. PMID:17539428

  13. Preliminary Depositional and Provenance Records of Mesozoic Basin Evolution and Cenozoic Shortening in the High Andes, La Ramada Fold-Thrust Belt, Southern-Central Andes (32-33°S)

    Science.gov (United States)

    Mackaman-Lofland, C.; Horton, B. K.; Fuentes, F.; Constenius, K. N.; McKenzie, R.; Alvarado, P. M.

    2015-12-01

    The Argentinian Andes define key examples of retroarc shortening and basin evolution above a zone of active subduction. The La Ramada fold-thrust belt (RFTB) in the High Andes provides insights into the relative influence and temporal records of diverse convergent margin processes (e.g. flat-slab subduction, convergent wedge dynamics, structural inversion). The RFTB contains Mesozoic extensional basin strata deformed by later Andean shortening. New detrital zircon U-Pb analyses of Mesozoic rift sediments reveal: (1) a dominant Permo-Triassic age signature (220-280 Ma) associated with proximal sources of effective basement (Choiyoi Group) during Triassic synrift deposition; (2) upsection younging of maximum depositional ages from Late Triassic through Early Cretaceous (230 to 100 Ma) with the increasing influence of western Andean arc sources; and (3) a significant Late Cretaceous influx of Paleozoic (~350-550 Ma) and Proterozoic (~650-1300 Ma) populations during the earliest shift from back-arc post-extensional subsidence to upper-plate shortening. The Cenozoic detrital record of the Manantiales foreland basin (between the Frontal Cordillera and Precordillera) records RFTB deformation prior to flat-slab subduction. A Permo-Triassic Choiyoi age signature dominates the Miocene succession, consistent with sources in the proximal Espinacito range. Subordinate Mesozoic (~80-250 Ma) to Proterozoic (~850-1800 Ma) U-Pb populations record exhumation of the Andean magmatic arc and recycling of different structural levels in the RFTB during thrusting/inversion of Mesozoic rift basin strata and subjacent Paleozoic units. Whereas maximum depositional ages of sampled Manantiales units cluster at 18-20 Ma, the Estancia Uspallata basin (~50 km to the south) shows consistent upsection younging of Cenozoic populations attributed to proximal volcanic centers. Ongoing work will apply low-temperature thermochronology to pinpoint basin accumulation histories and thrust timing.

  14. Current deformation of the Betic Cordillera from a new GPS observation of the southern sector of the IBERIA95 Zero-Order Geodetic Network

    Science.gov (United States)

    Gil, Antonio J.; Galindo, Jesús; Alfaro, Pedro; de Lacy, María. Clara; Jesús Borque, María.; Franco, Juan A. Armenteros (1), Oscar; Ruano, Patricia; García Tortosa, Francisco Juan; López Garrido, Angel Carlos; Pedrera, Antonio

    2010-05-01

    The Betic Cordillera, located at the convergent plate boundary between Africa and Eurasia, is subjected to an average NNW-SSE compression and an associated orthogonal extension. In order to quantify this deformation a GPS campaign in the Southern Sector of IBERIA95 Zero-Order Geodetic Network was done in December 2008. This network was observed in 1995 by the Spanish National Geographical Institute (IGNE) and the Portuguese Institute of Cartography and Cadastre (IPCC) for the establishment of a Three-dimensional Geodetic Network in Spain and Portugal. The comparison of results in 1995 and 2009 provides one of the first geodetic results of the short-term deformation in the Betic Cordillera.

  15. Phlebotomine sandflies (Diptera: Psychodidae in a sub-Andean forest from the Norte de Santander, Colombia

    Directory of Open Access Journals (Sweden)

    Richard Hoyos-López

    2016-01-01

    Full Text Available Background & objectives: The recognition of communities of arthropods with medical importance in natural systems constitutes an important step in the prediction of possible epidemic events and/or emergence of infectious diseases in the human population. This is due to anthropogenic impact in natural areas and landscape modification, which changes the dynamics of pathogenic agents, reservoirs, and vector insects. In this study, an inventory was compiled of species of the genus Lutzomyia present in sub-Andean forest from the confluence of the Pamplonita River basin. Methods: CDC-light and Shannon traps were used for collecting adult phlebotomine sandflies during the month of October 2013 in a sub-Andean forest from river basin Pamplonita. All specimens were identified using morphological keys. The epidemiological relevance of each species was reported using a literature review about natural infection or vector incrimination with Leishmania species or other pathogens microorganism. Results: A total of 2755 specimens belonging to eight species of the genus Lutzomyia were collected. Out of the eight species, seven belonged to the group verrucarum (Lutzomyia sp - townsendi series, L. ovallesi, L. spinicrassa, L. serrana, L. townsendi, L. nuneztovari and L. pia, while one belonged to the subgenus Helcocyrtomyia (L. hartmanni. A new registry of L. townsendi was observed for the Norte de Santander department. Interpretation & conclusion: The appreciable diversity of the verrucarum group observed in this area suggest further investigation on the biogeography and evolution of this group, and epidemiological risk for human populations around this area, as there are reports of Leishmania natural infection and favourable conditions for domestication of phlebotomines in rural towns.

  16. Genome-Wide Association Study of Anthracnose Resistance in Andean Beans (Phaseolus vulgaris.

    Directory of Open Access Journals (Sweden)

    Grady H Zuiderveen

    Full Text Available Anthracnose is a seed-borne disease of common bean (Phaseolus vulgaris L. caused by the fungus Colletotrichum lindemuthianum, and the pathogen is cosmopolitan in distribution. The objectives of this study were to identify new sources of anthracnose resistance in a diverse panel of 230 Andean beans comprised of multiple seed types and market classes from the Americas, Africa, and Europe, and explore the genetic basis of this resistance using genome-wide association mapping analysis (GWAS. Twenty-eight of the 230 lines tested were resistant to six out of the eight races screened, but only one cultivar Uyole98 was resistant to all eight races (7, 39, 55, 65, 73, 109, 2047, and 3481 included in the study. Outputs from the GWAS indicated major quantitative trait loci (QTL for resistance on chromosomes, Pv01, Pv02, and Pv04 and two minor QTL on Pv10 and Pv11. Candidate genes associated with the significant SNPs were detected on all five chromosomes. An independent QTL study was conducted to confirm the physical location of the Co-1 locus identified on Pv01 in an F4:6 recombinant inbred line (RIL population. Resistance was determined to be conditioned by the single dominant gene Co-1 that mapped between 50.16 and 50.30 Mb on Pv01, and an InDel marker (NDSU_IND_1_50.2219 tightly linked to the gene was developed. The information reported will provide breeders with new and diverse sources of resistance and genomic regions to target in the development of anthracnose resistance in Andean beans.

  17. Acceleration and novelty: community restoration speeds recovery and transforms species composition in Andean cloud forest.

    Science.gov (United States)

    Wilson, Sarah Jane; Rhemtulla, Jeanine M

    2016-01-01

    Community-based tropical forest restoration projects, often promoted as a win-win solution for local communities and the environment, have increased dramatically in number in the past decade. Many such projects are underway in Andean cloud forests, which, given their extremely high biodiversity and history of extensive clearing, are understudied. This study investigates the efficacy of community-based tree-planting projects to accelerate cloud forest recovery, as compared to unassisted natural regeneration. This study takes place in northwest Andean Ecuador, where the majority of the original, highly diverse cloud forests have been cleared, in five communities that initiated tree-planting projects to restore forests in 2003. In 2011, we identified tree species along transects in planted forests (n = 5), naturally regenerating forests (n = 5), and primary forests (n = 5). We also surveyed 120 households about their restoration methods, tree preferences, and forest uses. We found that tree diversity was higher in planted than in unplanted secondary forest, but both were less diverse than primary forests. Ordination analysis showed that all three forests had distinct species compositions, although planted forests shared more species with primary forests than did unplanted forests. Planted forests also contained more animal-dispersed species in both the planted canopy and in the unplanted, regenerating understory than unplanted forests, and contained the highest proportion of species with use value for local people. While restoring forest increased biodiversity and accelerated forest recovery, restored forests may also represent novel ecosystems that are distinct from the region's previous ecosystems and, given their usefulness to people, are likely to be more common in the future. PMID:27039520

  18. Hydrological connectivity of alluvial Andean valleys: a groundwater/surface-water interaction case study in Ecuador

    Science.gov (United States)

    Guzmán, Pablo; Anibas, Christian; Batelaan, Okke; Huysmans, Marijke; Wyseure, Guido

    2016-06-01

    The Andean region is characterized by important intramontane alluvial and glacial valleys; a typical example is the Tarqui alluvial plain, Ecuador. Such valley plains are densely populated and/or very attractive for urban and infrastructural development. Their aquifers offer opportunities for the required water resources. Groundwater/surface-water (GW-SW) interaction generally entails recharge to or discharge from the aquifer, dependent on the hydraulic connection between surface water and groundwater. Since GW-SW interaction in Andean catchments has hardly been addressed, the objectives of this study are to investigate GW-SW interaction in the Tarqui alluvial plain and to understand the role of the morphology of the alluvial valley in the hydrological response and in the hydrological connection between hillslopes and the aquifers in the valley floor. This study is based on extensive field measurements, groundwater-flow modelling and the application of temperature as a groundwater tracer. Results show that the morphological conditions of a valley influence GW-SW interaction. Gaining and losing river sections are observed in narrow and wide alluvial valley sections, respectively. Modelling shows a strong hydrological connectivity between the hillslopes and the alluvial valley; up to 92 % of recharge of the alluvial deposits originates from lateral flow from the hillslopes. The alluvial plain forms a buffer or transition zone for the river as it sustains a gradual flow from the hills to the river. Future land-use planning and development should include concepts discussed in this study, such as hydrological connectivity, in order to better evaluate impact assessments on water resources and aquatic ecosystems.

  19. Diversity patterns of selected Andean plant groups correspond to topography and habitat dynamics, not orogeny

    Directory of Open Access Journals (Sweden)

    Jens eMutke

    2014-10-01

    Full Text Available The tropical Andes are a hotspot of biodiversity, but detailed altitudinal and latitudinal distribution patterns of species are poorly understood. We compare the distribution and diversity patterns of four Andean plant groups on the basis of georeferenced specimen data: the genus Nasa (Loasaceae, the two South American sections of Ribes (sect. Parilla and sect. Andina, Grossulariaceae, and the American clade of Urtica (Urticaceae. In the tropical Andes, these often grow together, especially in (naturally or anthropogenically disturbed or secondary vegetation at middle to upper elevations. The climatic niches of the tropical groups studied here are relatively similar in temperature and temperature seasonality, but do differ in moisture seasonality. The Amotape-Huancabamba Zone (AHZ between 3–8° S shows a clear diversity peak of overall species richness as well as for narrowly endemic species across the groups studied. For Nasa, we also show a particular diversity of growth forms in the AHZ. This can be interpreted as proxy for a high diversity of ecological niches based on high spatial habitat heterogeneity in this zone. Latitudinal ranges are generally larger towards the margins of overall range of the group. Species number and number of endemic species of our taxa peak at elevations of 2,500–3,500 m in the tropical Andes. Altitudinal diversity patterns correspond well with the altitudinal distribution of slope inclination. We hypothesize that the likelihood and frequency of landslides at steeper slopes translates into temporal habitat heterogeneity. The frequency of landslides may be causally connected to diversification especially for the numerous early colonizing taxa, such as Urtica and annual species of Nasa. In contrast to earlier hypotheses, uplift history is not reflected in the pattern here retrieved, since the AHZ is the area of the most recent Andean uplift. Similarly, a barrier effect of the low-lying Huancabamba depression is

  20. Acceleration and novelty: community restoration speeds recovery and transforms species composition in Andean cloud forest.

    Science.gov (United States)

    Wilson, Sarah Jane; Rhemtulla, Jeanine M

    2016-01-01

    Community-based tropical forest restoration projects, often promoted as a win-win solution for local communities and the environment, have increased dramatically in number in the past decade. Many such projects are underway in Andean cloud forests, which, given their extremely high biodiversity and history of extensive clearing, are understudied. This study investigates the efficacy of community-based tree-planting projects to accelerate cloud forest recovery, as compared to unassisted natural regeneration. This study takes place in northwest Andean Ecuador, where the majority of the original, highly diverse cloud forests have been cleared, in five communities that initiated tree-planting projects to restore forests in 2003. In 2011, we identified tree species along transects in planted forests (n = 5), naturally regenerating forests (n = 5), and primary forests (n = 5). We also surveyed 120 households about their restoration methods, tree preferences, and forest uses. We found that tree diversity was higher in planted than in unplanted secondary forest, but both were less diverse than primary forests. Ordination analysis showed that all three forests had distinct species compositions, although planted forests shared more species with primary forests than did unplanted forests. Planted forests also contained more animal-dispersed species in both the planted canopy and in the unplanted, regenerating understory than unplanted forests, and contained the highest proportion of species with use value for local people. While restoring forest increased biodiversity and accelerated forest recovery, restored forests may also represent novel ecosystems that are distinct from the region's previous ecosystems and, given their usefulness to people, are likely to be more common in the future.

  1. Genome-Wide Association Study of Anthracnose Resistance in Andean Beans (Phaseolus vulgaris).

    Science.gov (United States)

    Zuiderveen, Grady H; Padder, Bilal A; Kamfwa, Kelvin; Song, Qijian; Kelly, James D

    2016-01-01

    Anthracnose is a seed-borne disease of common bean (Phaseolus vulgaris L.) caused by the fungus Colletotrichum lindemuthianum, and the pathogen is cosmopolitan in distribution. The objectives of this study were to identify new sources of anthracnose resistance in a diverse panel of 230 Andean beans comprised of multiple seed types and market classes from the Americas, Africa, and Europe, and explore the genetic basis of this resistance using genome-wide association mapping analysis (GWAS). Twenty-eight of the 230 lines tested were resistant to six out of the eight races screened, but only one cultivar Uyole98 was resistant to all eight races (7, 39, 55, 65, 73, 109, 2047, and 3481) included in the study. Outputs from the GWAS indicated major quantitative trait loci (QTL) for resistance on chromosomes, Pv01, Pv02, and Pv04 and two minor QTL on Pv10 and Pv11. Candidate genes associated with the significant SNPs were detected on all five chromosomes. An independent QTL study was conducted to confirm the physical location of the Co-1 locus identified on Pv01 in an F4:6 recombinant inbred line (RIL) population. Resistance was determined to be conditioned by the single dominant gene Co-1 that mapped between 50.16 and 50.30 Mb on Pv01, and an InDel marker (NDSU_IND_1_50.2219) tightly linked to the gene was developed. The information reported will provide breeders with new and diverse sources of resistance and genomic regions to target in the development of anthracnose resistance in Andean beans. PMID:27270627

  2. Flujos de detritos recientes en la cordillera frontal de Mendoza: Un ejemplo de riesgo natural en la ruta 7 Recent debris flows in the Frontal Cordillera of Mendoza: an example of natural risk on the Road 7

    Directory of Open Access Journals (Sweden)

    Emmanuel Wick

    2010-06-01

    Full Text Available Se expone un estudio sobre los flujos de detritos ocurridos en enero de 2005, en el km 1.118,5 de la ruta nacional 7 en la provincia de Mendoza. La zona se ubica en la Cordillera Frontal, próxima al límite con la Precordillera. Se realizó un mapa geomorfológico detallado, sobre la base de una imagen Quickbird del año 2006. Además, se hicieron cálculos de volúmenes, velocidades y caudales, con mediciones en el campo y con ayuda de un sistema de información geográfico (SIG. El estudio de la geomorfología permitió proponer tres escenarios para el caso de un nuevo evento, a partir de los cuáles se creó un mapa de susceptibilidad a los flujos de detritos para el tramo de ruta analizado. Finalmente, se proponen medidas de protección y de mitigación ante la posibilidad de recurrencia de estos eventos en el sector.In this paper is presented a study dealing with the debris flows that reached the national road 7 in January 2005, in the km 1,118.5, Mendoza province. The area is located in the Frontal Cordillera near the limit of the Precordillera. A detailed geomorphologic map has been realized for this study using a Quickbird satellite imagery of the year 2006. Various calculations of volumes, velocities and peak discharges have been performed with the field data and using a geographic information system (GIS. The geomorphologic survey has permitted to propose three propagation scenarios in case of a new event. These allowed creating a map of debris flows susceptibility for the stretch of the road that has been studied. Finally, it has been proposed protection and mitigation measures, based on the results of the study, to protect the road from a new event.

  3. La sección Messiniense - Plioceno de Crevillente (Cordillera Bética oriental): expresión de la crisis de salinidad del Mediterráneo

    OpenAIRE

    Soria, Jesús M.; Yébenes, Alfonso; Caracuel, Jesús Esteban

    2001-01-01

    A composite stratigraphic section in Crevillente (eastern Betic Cordillera) is studied. It represent a complete stratigraphical and paleontological record of the Messinian and Lower Pliocene. Two discontinuity surfaces related to the Mediterranean salinity crisis are analysed: a intra-messinian surface which coincides with a sea-level fall leading to the emergence of this area far from marine influences; and an uppermost Messinian unconformity, with strong erosionaI character, overlied by mar...

  4. The Messinian–early Pliocene stratigraphic record in the southern Bajo Segura Basin (Betic Cordillera, Spain): Implications for the Mediterranean salinity crisis

    OpenAIRE

    Soria, J. M.; Departamento Ciencias de la Tierra y del Medio Ambiente, Universidad de Alicante, Apdo. 99, San Vicente del Raspeig, 03080 Alicante; Caracuel, J. E.; Departamento de Ciencias de la Tierra y del Medio Ambiente, Universidad de Alicante, Apdo. Correos 99, 03080 Alicante, Spain; Corbí, H.; Departamento de Ciencias de la Tierra y del Medio Ambiente, Universidad de Alicante, Apdo. Correos 99, 03080 Alicante, Spain; Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Lancis, C.; Departamento de Ciencias de la Tierra y del Medio Ambiente, Universidad de Alicante, Apdo. Correos 99, 03080 Alicante, Spain; Tent-Manclús, J. E.; Departamento de Ciencias de la Tierra y del Medio Ambiente, Universidad de Alicante, Apdo. Correos 99, 03080 Alicante, Spain; Viseras, C.; Departamento de Estratigrafía y Paleontología, Universidad de Granada, Campus de Fuente Nueva s/n, 18071 Granada, Spain; Yébenes, A.; Departamento de Ciencias de la Tierra y del Medio Ambiente, Universidad de Alicante, Apto. 99, 03080 San Vicente del Raspeig, Alicante, Spain

    2008-01-01

    The analysis of the Messinian and Pliocene stratigraphy of the southern Bajo Segura Basin (Betic Cordillera, Spain) has revealed three highstand sedimentary phases (Messinian I, Messinian II, and Pliocene) bounded by two lowstand erosional surfaces (intra-Messinian and end-Messinian unconformities). The Messinian I highstand phase is characterized by the progradation of coastal and shallow marine sandstones (La Virgen Fm) over slope and pelagic-basin marls (Torremendo Fm). After this first ph...

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

    OpenAIRE

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

    2015-01-01

    Seasonal snow cover is the primary water resource precursor for human use and environmental sustain along the extratropical Andes Cordillera. Despite its importance, relatively little research has been devoted to understanding the properties, distribution and variability of this natural resource. This research provides high-resolution distributed estimates of end-of-winter and spring snow water equivalent over a 152 000 km2 domain that includes the mountainous reaches of ...

  6. Contribution of groundwater to the outflow from ungauged glacierized catchments : a multi-site study in the tropical Cordillera Blanca, Peru

    OpenAIRE

    M. Baraer; McKenzie, J.; B. G. Mark; Gordon, R.; Bury, J.; Condom, Thomas; J. Gomez; S. Knox; S. K. Fortner

    2015-01-01

    The rapid retreat of the glaciers of the Cordillera Blanca is having a noticeable impact on the downstream hydrology. Although groundwater is a critical hydrologic component that sustains stream flows during the dry season, its characteristics and its contribution to downstream hydrology remain poorly understood. In this study, we analyse the hydrochemical and isotopic properties of potential hydrologic sources mixing in surface streams to characterize the proglacial hydrology in four glacial...

  7. Monitoring adherence to the international code of conduct: highly hazardous pesticides in central Andean agriculture and farmers' rights to health.

    Science.gov (United States)

    Orozco, Fadya A; Cole, Donald C; Forbes, Greg; Kroschel, Jürgen; Wanigaratne, Susitha; Arica, Denis

    2009-01-01

    The WHO has advocated monitoring adherence to the Food and Agriculture Organization's Code of Conduct to reduce use of highly hazardous pesticides in lower and middle income countries. We re-framed Code articles in terms of farmers' rights and drew on survey data, farmer focus group results, and direct observations of agrochemical stores in Ecuador and Peru to construct indicators reflecting respect for such rights. Use of highly (Ia and Ib) and moderately (II) hazardous pesticides was common. Worse indicators were observed in places with lower education, greater poverty, and more use of indigenous languages. Limited government enforcement capacity, social irresponsibility of the pesticide industry, and lack of farmers' knowledge of the Code were all factors impeding respect for farmers' rights. Addressing the power imbalance among social actors requires informed farmer and farmworker participation in monitoring adherence and active involvement of non-governmental organizations and municipal governments. PMID:19650580

  8. Vivid valleys, pallid peaks? Hypsometric variations and rural–urban land change in the Central Peruvian Andes

    OpenAIRE

    Haller, Andreas

    2012-01-01

    What happens to the land cover within the hinterland's altitudinal belts while Central Andean cities are undergoing globalization and urban restructuring? What conclusions can be drawn about changes in human land use? By incorporating a regional altitudinal zonation model, direct field observations and GIS analyses of remotely sensed long term data, the present study examines these questions using the example of Huancayo Metropolitano – an emerging Peruvian mountain city of 420,000 inhabitant...

  9. La porosidad en las areniscas triásicas (Rama Aragonesa de la Cordillera Ibérica

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    Arribas, J.

    1984-12-01

    Full Text Available Triassic sandstone's porosity (Buntsandstein and Muschelkalk facies from the Aragonesa Branch of the Iberian Range are studied, firstly at the sediment primary porosity calculation and secondly the porosity-reducing processes are analyzed. Processes creating secondary sandstone porosity can be established (dissolution and fracturing by the textural and genetic caracterization of the sandstone's voids. The dissolution of potassium feldspar, carbonate cement and barite cement, is related with meteoric pore-water flow alloys to intramesozoic unconformities, Fracturing porosity is related to Iberian Range tertiary structuration. Finally, we concluded that the amount of the sandstone's secondary porosity depends mainly on the original composition of the sediments and also on the geochemical sedimentary environments that control the first diagenetic stages (eodiagenesis, This fact manifests itself in the amount and types of variating porosities along the stratigraphic section.

    Se estudia la porosidad en las areniscas triásicas (facies Buntsandstein y Muschelkalk de la Rama Aragonesa de la Cordillera Ibérica, partiendo del cálculo estimativo de la porosidad primaria del sedimento, para posteriormente analizar los distintos procesos diagenéticos que han intervenido en su destrucción (compactación mecánica, compactación química y cementación. La caracterización textural y genética de los poros en dichas areniscas permite establecer la existencia de procesos generadores de porosidad secundaria (disolución y fractura. La disolución del feldespato potásico, cemento carbonático y de baritina se relaciona con flujos de aguas meteóricas ligadas a discordancias intramesozoicas, mientras que la porosidad de fractura se asocia a la estructuración terciaria de la Cordillera Ibérica. Por ú1timo se concluye que la cantidad de porosidad secundaria en las areniscas estudiadas depende fundamentalmente de la composición original de los dep

  10. ARTE EN LA ZONA DE HISTÉRESIS: QUEBRADA. LAS CORDILLERAS EN ANDAS DE GUADALUPE SANTA CRUZ Art in the Zone of Hysteresis: Quebrada. Las cordilleras en andas, by Guadalupe Santa Cruz

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    Cecilia Ojeda

    2007-12-01

    Full Text Available Este libro de Guadalupe Santa Cruz plantea el problema del desmedrado estatus del arte en un horizonte cultural dominado por la industria del entretenimiento. De este reconocimiento y del diseño vanguardista del libro en sí -concebido como un puente entre el arte y la vida, o como un instrumento de conocimiento privilegiado de lo real- surge una tensión característica del arte contemporáneo. Dicha tensión ha sido definida como el punto de histéresis de la obra artística en la que ésta tiende a conservar una propiedad en ausencia del estímulo que la ha generado, tensión artística que se examina en este ensayo.Quebrada. Las cordilleras en andas examines the issue of the artwork’s diminished status within a landscape dominated by the entertainment industry. From this knowledge and the vanguard design of the book itself -as an instrument of the real-arises a tension that is characteristic of contemporary art. This tension has been compared to the point of hysteresis of an element, in which like a magnetic material it, the work of art, preserves one of its properties in the absence of its stimulus. This essay examines how this tension is produced in the work by Guadalupe Santa Cruz.

  11. Mantle to Surface Fluid Transfer Above a Flat Slab Subduction Zone: Isotopic Evidence from Hot Springs in the Cordillera Blanca, Peru

    Science.gov (United States)

    Newell, D. L.; Jessup, M. J.; Hilton, D. R.; Shaw, C. A.; Hughes, C. A.

    2015-12-01

    Thermal springs in the Cordillera Blanca, Peru, provide geochemical evidence for deeply circulated hydrothermal fluids that carry significant mantle-derived helium. The Cordillera Blanca is a ~200 km-long NNW-SSE trending mountain range in the Peruvian Andes located above an amagmatic flat-slab subduction segment. The west side of the range is bounded by the Cordillera Blanca detachment that preserves a progression of top to the west ductile shear to brittle normal faulting since ~5 Ma. We report aqueous and stable isotope geochemical results from fluid and gas samples collected in 2013 and 2015 from 13 hot springs emanating from the Cordillera Blanca detachment and associated hanging wall faults. Most springs are vigorously bubbling (degassing), and range in temperature, pH, and conductivity from 17-89 °C, 5.95-8.87, and 0.17-21.5 mS, respectively. The hottest springs issue directly from the northern segment of the detachment. Geochemically, springs are CO2-rich, alkaline-chloride to alkaline-carbonate waters, with elevated trace metal contents including Fe, Cu, As, Zn, Sb, and Tl. Notably, As contents are ≤11 ppm, indicating that thermal waters may be adversely impacting local water quality. Water δ18O and δD, trends in elemental chemistry, and cation geothermometry collectively demonstrate mixing of hot (200-260 °C) saline fluid with cold meteoric recharge along the fault. Helium isotope ratios (3He/4He) for dissolved gases in the hot springs range from 0.62 to 1.98 RC/RA, indicating the presence of ~25% mantle-derived helium, assuming mixing of an asthenospheric end-member with the crustal helium reservoir. CO2/3He and carbon stable isotope ratios indicate a carbon source derived from mixing of crustal sources with minor mantle carbon. Overall, the volatile signature overlaps with orogen-wide datasets where crustal overprinting has modified mantle contributions at active arc volcanoes. Given the long duration since active magmatism in the Cordillera

  12. Analysis of Genetic Variability among thirty accessions of Andean Lupin (Lupinus mutabilis Sweet using ISSR molecular markers

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    Michelle C. Chirinos-Arias

    2015-03-01

    Full Text Available In order to make the genetic variability analysis among thirty accessions of andean lupine (L. mutabilis Sweet belonging to Agrarian Innovation National Institute (INIA Seed Bank. DNA was extracted from 300 plants and we made bulks. We standardized amplification protocol of Inter Simple Sequence Repeat (ISSR primers, we chose the most polymorphic primers to run in acrylamide gel. We found 255 ISSR loci with 8 primers. It was found high genetic variability of the samples under study by ISSR markers. Also observed relatively high polymorphism for autogamous species such as andean lupine. Finally phenograms showed a relationship with the geographical location, possibly due to in situ gene flow due to the exchange or sale of seeds in markets near the collection area.

  13. Culturas indígenas de la región andina - Indian cultures of the Andean region

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    MOLNÁR, Gábor

    2014-09-01

    Full Text Available The A ndean region is an autonomous and well delimited geographical region of Latin America, but from a cultural geographical point of view it is not concerned as a completely homogeneous territory. The physical geography given by the chains of the Andean mountains was the common basis for several civilizations and cultures of different levels of development and different extensions in time and in space appeared there during thousands of years. Most of them – not without reference to the arrival of the Europeans – completely or partially disappeared. However some elements of their cultures are taking part of the actual mestic reality that is in continuous changing nowadays too. At the same time the natives living today in the Andean region, from the Guajira Peninsula to the Tierra del Fuego, belong to dozens of etnical groups and aproximately 10-15 million people among all Indians of Latin America live in this region.

  14. Preliminary checklist of the vascular flora of the Sub-Andean forest at Cuchilla El Fara (Santander-Colombia)

    International Nuclear Information System (INIS)

    A preliminary checklist of the vascular flora of the sub-Andean forest of the Cuchilla El Fara is present ed. El Fara is located at the Guantiva - La Rusia - Iguaque biological corridor, in the municipalities of Charala, Gambita, and Suaita (Santander-Colombia). Information on habit, local altitudinal range, and collection number is recorded for each species. A total of 409 species of vascular plants included in 226 genera, and 105 families were recorded. The families with the highest number of genera were Rubiaceae (18), Asteraceae (10), Melastomataceae (10), Orchidaceae (10), Euphorbiaceae (8), Arecaceae (7) and Fabaceae (7). At specific level, the best represented families were Rubiaceae (33), Melastomataceae (28), Lauraceae (21), Asteraceae (17), Araceae (17), Orchidaceae (17) and Gesneriaceae (15). The affinities of the flora with other Neotropical sub-Andean forests are discussed. Finally, species of all IUCN threat categories are highlighted so that the information presented here can make a contribution to restoration and conservation programs.

  15. Can Andean medicine coexist with biomedical healthcare? A comparison of two rural communities in Peru and Bolivia

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    Mathez-Stiefel Sarah-Lan

    2012-07-01

    Full Text Available Abstract Background It is commonly assumed that indigenous medical systems remain strong in developing countries because biomedicine is physically inaccessible or financially not affordable. This paper compares the health-seeking behavior of households from rural Andean communities at a Peruvian and a Bolivian study site. The main research question was whether the increased presence of biomedicine led to a displacement of Andean indigenous medical practices or to coexistence of the two healing traditions. Methodology Open-ended interviews and free listing exercises were conducted between June 2006 and December 2008 with 18 households at each study site. Qualitative identification of households’ therapeutic strategies and use of remedies was carried out by means of content analysis of interview transcriptions and inductive interference. Furthermore, a quantitative assessment of the incidence of culture-bound illnesses in local ethnobiological inventories was performed. Results Our findings indicate that the health-seeking behavior of the Andean households in this study is independent of the degree of availability of biomedical facilities in terms of quality of services provided, physical accessibility, and financial affordability, except for specific practices such as childbirth. Preference for natural remedies over pharmaceuticals coexists with biomedical healthcare that is both accessible and affordable. Furthermore, our results show that greater access to biomedicine does not lead to less prevalence of Andean indigenous medical knowledge, as represented by the levels of knowledge about culture-bound illnesses. Conclusions The take-home lesson for health policy-makers from this study is that the main obstacle to use of biomedicine in resource-poor rural areas might not be infrastructural or economic alone. Rather, it may lie in lack of sufficient recognition by biomedical practitioners of the value and importance of indigenous medical systems

  16. Crown Jewel of the Fleet: Design, Construction, and Use of the Seagoing Balsa of the Pre-Columbian Andean Coast

    OpenAIRE

    Emanuel, Jeffrey Paul

    2012-01-01

    The seaworthiness of the balsa sailing raft, and the seafaring aptitude of those who built and sailed it, has been the subject of critically biased, often conflicting accounts over the nearly five centuries since contact. This paper objectively marshals historical evidence to recover the preColumbian design and construction of this ‘Crown Jewel’ of the coastal Andean fleet. Sailing balsas were constructed of balsa tree (ochroma spp.) trunks lashed together with henequen, covered with one or m...

  17. Populations of Odontesthes (Teleostei: Atheriniformes) in the Andean region of Southern South America: body shape and hybrid individuals

    OpenAIRE

    Cecilia Conte-Grand; Julie Sommer; Guillermo Ortí; Víctor Cussac

    2015-01-01

    The original distribution area of the Patagonian 'pejerrey' Odontesthes hatcheri has been subjected to the introduction of a related species; the Bonaerensean 'pejerrey' Odontesthes bonariensis. This species currently coexists with O. hatcheri in lakes and reservoirs, and can interbreed and produce fertile hybrid offspring. The purposes of this study were; a) the extensive sampling of Patagonian and Andean-Cuyan populations of pejerrey, b) the species identification according to taxonomic key...

  18. Erratum - Assessing the effects of climate and volcanism on diatom and chironomid assemblages in an Andean lake near Quito, Ecuador

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    Neal Michelutti

    2016-02-01

    Full Text Available This corrects the article entitled “Assessing the effects of climate and volcanism on diatom and chironomid assemblages in an Andean lake near Quito, Ecuador” by the authors Neal Michelutti, Jillian L. Lemmen, Colin A. Cooke, William O. Hobbs, Alexander P. Wolfe, Joshua Kurek, John P. Smol, published with DOI 10.4081/jlimnol.2015.1323. The map in Fig. 1 was incorrectly labelled and the correct version of Fig. 1 is presented below.

  19. Variability in New Shortening Estimates from Southern Peru (12-14S); Implications for Mass Balance of the Andean Plateau.

    Science.gov (United States)

    Gotberg, N.; McQuarrie, N.

    2008-12-01

    One of the fundamental questions of interest with regards to the Andean Plateau is the mass balance of material needed to create and sustain a 3-4 km high plateau. Is crustal shortening sufficient to support an isostatically compensated crust of 60-70km? We present new estimates of shortening across the northern margin of the Andean Plateau. The cross section extent, from the eastern edge of the volcanic arc to foreland basin, is approximately one half of the physiographic width of the Andean Plateau in Peru. Cross sectional shortening estimates in southern Peru (12-14°S) provide a best estimate of 123 km or 40% shortening with an absolute minimum estimate of 86 km or 30% and absolute maximum estimate of 275 km or 60%. We determined the maximum and minimum shortening estimates using the cross sectional area and possible variations in assumptions made about the amount of erosion, detachment dip, involvement of basement thrusts and displacement along faults. The best estimate of shortening is well short of the required 240-300km of shortening needed in order to account for a 60-70km thick crust under the entire plateau. This suggests that for an isostatically equilibrated crust either 1) there is a significant amount of shortening (~150km) in the western half of the plateau which, is hidden by the volcanic arc or 2) crustal material is being added to the Peruvian section of the Andean Plateau either through lower crustal flow or a process of magmatic underplating followed by differentiation and delamination.

  20. A geomorphological approach to determining the Neogene to Recent tectonic deformation in the Coastal Cordillera of northern Chile (Atacama)

    Science.gov (United States)

    Riquelme, R.; Martinod, J.; Hérail, G.; Darrozes, J.; Charrier, R.

    2003-01-01

    The large (≈10000 km 2) and local-scale (Atacama Fault System (AFS) accommodated the relative uplift of the western side of the Chilean Coastal Cordillera of the Chañaral region (southern Atacama Desert). The mean regional altitude systematically decreases eastwards crossing the AFS, independent of the lithological characteristics of the substratum cut by this system of faults. Topographic analysis reveals a more incised landscape west of the AFS that, at the local scale, is reported by the distribution of the altitudes (hypsometric curves and integrals) of tributary basins and by the presence of terraces. In the Middle and Upper Miocene, a thick (>300 m) sedimentary succession was deposited east of the AFS. The succession fills previously deep paleovalleys. And it consists of gravel, so-called "Atacama Gravels", which passes laterally into fine-grained playa related deposits near the AFS. We interpret the deposition of this succession as a result of a blocking closure of the valley flowing from the Precordillera due to the activity on AFS. A pedimentation episode followed sediment deposition and is locally strongly re-incised by the main modern-day river valleys draining the Precordillera. Incision may result from either regional uplift of the forearc, and/or from more localized activity on the AFS. Furthermore, Recent (Quaternary?) tectonic activity on the AFS has been observed which is consistent with a localized relative uplift of the crustal block west of the AFS.

  1. On the lag time between internal strain and basement involved thrust induced exhumation: The case of the Colombian Eastern Cordillera

    Science.gov (United States)

    Mora, Andrès; Blanco, Vladimir; Naranjo, Julian; Sanchez, Nelson; Ketcham, Richard A.; Rubiano, Jorge; Stockli, Daniel F.; Quintero, Isaid; Nemčok, Michal; Horton, Brian K.; Davila, Hamblet

    2013-07-01

    Thrust sheets accumulate internal strain before they start moving along discrete fault planes. However, there are no previous studies evaluating the time difference between initiation of strain and fault displacement. In this paper we use observations from the Eastern Cordillera of Colombia to evaluate this interval. We utilize multiple thermochronometers and paleothermometers to refine the timing of deformation. Based on these new data we build time-temperature path estimates that together with geometric outcrop-based structural analysis and fluid inclusions allow us to assign relative timing to features associated with strain, such as cleavage, veins and certain types of fractures, and compare that with the timing of thrusting. We find that cleavage was only formed close to maximum paleotemperatures, almost coeval with the onset of thrust-induced denudation by the Late Oligocene. The corresponding structural level of fold-related veins suggest that they were formed later but still when the country rocks were at temperatures higher than 160 °C, mostly during the Early Miocene and still coexisted with the latest stages of cleavage formation. Our data show that the main period of strain hardening was short (probably a few million years) and occurred before first-order basement thrusting was dominant, but was associated with second-order folding.

  2. Snow water equivalent spatiotemporal variability estimation in the Andes Cordillera through distributed energy balance modeling and intensive-study catchments.

    Science.gov (United States)

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

    2015-12-01

    Seasonal snow cover is the primary water resource precursor for human use and environmental sustain along the extratropical Andes Cordillera. This research provides high-resolution distributed estimates of end-of-winter and spring snow water equivalent over a 152,000-km2 domain, based on remotely sensed snow cover and a simplified snowpack energy balance model. Important data for model validation was obtained through a sustained effort aimed at monitoring snow conditions throughout the domain from newly installed sensors and snow surveys. Peak SWE estimates show an overall coefficient of determination R2 of 0.61 compared to observations at 12 automatic snow water equivalent sensors distributed across the model domain between latitudes 30º S and 37º S, with R2 values between 0.32 and 0.88. Estimated patterns of snow accumulation reflect appropriately the dominant effect of elevation, and suggest that the current government operational snow observation network may be inadequate under future climate change scenarios. Several insights can be obtained by analyzing the shortcomings of the modeling results when compared with high-resolution time series of energy and mass balance, as well as with distributed SWE observations obtained at experimental catchments. The results presented here have the potential of informing applications such as seasonal forecast model assessment and improvement, regional climate model validation, as well as evaluation of observational networks and water resource infrastructure development.

  3. Flujos de detritos recientes en la cordillera frontal de Mendoza: Un ejemplo de riesgo natural en la ruta 7

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    Emmanuel Wick

    2010-06-01

    Full Text Available Se expone un estudio sobre los flujos de detritos ocurridos en enero de 2005, en el km 1.118,5 de la ruta nacional 7 en la provincia de Mendoza. La zona se ubica en la Cordillera Frontal, próxima al límite con la Precordillera. Se realizó un mapa geomorfológico detallado, sobre la base de una imagen Quickbird del año 2006. Además, se hicieron cálculos de volúmenes, velocidades y caudales, con mediciones en el campo y con ayuda de un sistema de información geográfico (SIG. El estudio de la geomorfología permitió proponer tres escenarios para el caso de un nuevo evento, a partir de los cuáles se creó un mapa de susceptibilidad a los flujos de detritos para el tramo de ruta analizado. Finalmente, se proponen medidas de protección y de mitigación ante la posibilidad de recurrencia de estos eventos en el sector.

  4. Space-time evolution of a growth fold (Betic Cordillera, Spain). Evidences from 3D geometrical modelling

    Science.gov (United States)

    Martin-Rojas, Ivan; Alfaro, Pedro; Estévez, Antonio

    2014-05-01

    We present a study that encompasses several software tools (iGIS©, ArcGIS©, Autocad©, etc.) and data (geological mapping, high resolution digital topographic data, high resolution aerial photographs, etc.) to create a detailed 3D geometric model of an active fault propagation growth fold. This 3D model clearly shows structural features of the analysed fold, as well as growth relationships and sedimentary patterns. The results obtained permit us to discuss the kinematics and structural evolution of the fold and the fault in time and space. The study fault propagation fold is the Crevillente syncline. This fold represents the northern limit of the Bajo Segura Basin, an intermontane basin in the Eastern Betic Cordillera (SE Spain) developed from upper Miocene on. 3D features of the Crevillente syncline, including growth pattern, indicate that limb rotation and, consequently, fault activity was higher during Messinian than during Tortonian; consequently, fault activity was also higher. From Pliocene on our data point that limb rotation and fault activity steadies or probably decreases. This in time evolution of the Crevillente syncline is not the same all along the structure; actually the 3D geometric model indicates that observed lateral heterogeneity is related to along strike variation of fault displacement.

  5. Plantas Fósiles del Grupo Choiyoi, Cordillera Frontal a la Latitud del río Mendoza

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    Magdalena Koukharsky

    2011-06-01

    Full Text Available En este trabajo se dan a conocer los primeros restos fósiles hallados en sedimentitas, cuyo componente clástico es de origen volcánico, intercaladas en la Formación Tambillos del Grupo Choiyoi, Cordillera Frontal de Mendoza. Los mismos consisten en abundantes improntas de Sphenophyta en estado de preservación regular a malo. En la zona estudiada, las rocas de la Formación Tambillos, que son dominantemente volcánicas ácidas y de edad pérmica temprana a media según correlaciones regionales, se depositaron sobre una discordancia erosiva labrada en lavas andesíticas intensamente propilitizadas que se atribuyen a la Formación Portezuelo del Cenizo. Los restos vegetales se encuentran a unos 23 metros de la base, contenidos en niveles de areniscas finas y pelitas depositadas en un ambiente fluvial (microdelta, en los bordes de un lago y fueron coetáneas con los primeros episodios de volcanismo riolítico en la región. Si bien la flora encontrada no permite definir la edad, las formas presentes son comunes en niveles del Carbonífero superior-Pérmico y Triásico de Argentina.

  6. Taxonomic review of the species of Helina R.-D. (Diptera: Muscidae) from Andean-Patagonian forests.

    Science.gov (United States)

    Patitucci, Luciano Damián; Mulieri, Pablo Ricardo; Mariluis, Juan Carlos

    2016-01-01

    Helina Robineau-Desvoidy, 1830 is the second genus of Muscidae in terms of richness. This genus includes several species collected at high altitudes and high latitudes, and is poorly studied in the Neotropical region. Only 12 species of Helina have been recorded in the southern limit of South America in the Andean-Patagonian forests. In the present work, we studied all the species known from the Andean-Patagonian forests, with the exception of H. viola Malloch, 1934, present three new species, H. araucana sp. nov., H. dorada sp. nov., and H. ouina sp. nov., and provide the first description of the females of H. australis Carvalho & Pont, 1993 and H. rufoapicata Malloch, 1934. We also propose four new synonymies: H. nigrimana basilaris (Carvalho & Pont, 1993) and H. nigrimana grisea (Malloch, 1934) as new junior synonyms of H. nigrimana (Macquart, 1851); and H. fulvocalyptrata Malloch, 1934 and H. simplex Malloch, 1934 as new junior synonyms of H. chilensis Malloch, 1934. Finally, we provide a generic diagnosis and a new key for the Helina species of the Andean-Patagonian forests, as well as notes on the biology and distribution maps of each specimen, and discuss a preliminary contruction of groups of species. PMID:27515658

  7. Multi-proxy reconstruction of the paleo-hydrological cycle during Andean Plateau uplift, NW-Argentina

    Science.gov (United States)

    Rohrmann, A.; Sachse, D.; Strecker, M. R.; Mulch, A.; Pingel, H.; Alonso, R. N.

    2014-12-01

    Controversies around the uplift history of the Central Andes may partly be due to the common use of single stable-isotope elevation proxies that are limited in recording the paleo-hydrological cycle during uplift. Our new, multi-proxy stable isotope data from 68 lipid biomarker n-alkanes, 62 soil carbonates (SC), and 15 volcanic glass shards (VG) from a well-dated section in the intermontane Angastaco Basin in the E Cordillera of NW Argentina (25°45 S, 66 W) provide insight into the paleo-hydrological cycle during uplift and outward growth of the adjacent Puna plateau's eastern margin. The samples cover a time interval from ~10 to 2 Ma with a resolution of ~ 0.2 Ma. C29 and C31 alkanes yield δD and δ13C values ranging from -95 to -160 ‰ (VSMOW) for δD and -23 to -36 ‰ (PDB) for δ13C. Measured SC range from 18 to 31 ‰ (VSMOW) for δ18O and -4 to -17 ‰ (PDB) for δ13C, whereas VG δD values range from -71 to -95 ‰ (VSMOW). In concert with published clumped-isotope temperature and VG data (Carrapa et al., 2014) our data indicate humid foreland conditions after 10 Ma that became drier at 6.5 Ma as a result of basin uplift and orographic barrier formation farther east. We constructed equidistant time series to calibrate and evaluate each proxy signal to determine which part of the hydrologic cycle is recorded and how each is influenced by regional surface uplift. The results show that water hydrating the VG reflects precipitation, whereas SC and n-alkanes record soil-water compositions. All three proxies show similar short-term trends in δD, δ18O and δ13C on timescales of ~1 Myr. For example, VG δD values show a gradual depletion during uplift from 6.5 to 4 Ma, whereas C29 and C31 δD values are D-enriched in response to basin aridification, which is in line with a change from C3 to C4 plants as recorded by δ13C C29 and C31. SC δ18O values show a buffered signal with a similar trend as δD of n-alkanes. As no modern C4 plants exist >2000 m (Cotton

  8. Modern and long-term evaporation of central Andes surface waters suggests paleo archives underestimate Neogene elevations

    Science.gov (United States)

    Fiorella, Richard P.; Poulsen, Christopher J.; Pillco Zolá, Ramiro S.; Jeffery, M. Louise; Ehlers, Todd A.

    2015-12-01

    Central Andean paleoelevations reconstructed from stable isotope and paleofloral data imply a large magnitude (>2 km) Miocene-to-modern surface uplift. However, the isotopic relationships between precipitation, surface waters, and soil waters upon which these reconstructions are based remain poorly constrained for both past, and in many cases, modern conditions. We quantify the relationships between central Andean precipitation and surface waters by measuring the isotopic composition of 249 stream water samples (δ18O and δD) collected between April 2009 and October 2012. The isotopic compositions of stream waters match precipitation along the eastern flank. In contrast, Altiplano surface waters possess a lower δD-δ18O slope (4.59 vs ∼8 for meteoric waters) not observed in precipitation, which signals heavy isotope evaporative enrichment in surface waters. Paleoclimate models indicate that highly evaporative conditions have persisted on the plateau throughout Andean uplift, and that conditions may have been more evaporative when the Andes were lower. Thus, more ancient proxy materials may have a greater evaporative bias than previously recognized and paleoelevation reconstructions from stable isotope based central Andean plateau proxy materials likely overstate Miocene-to-present surface uplift. We propose Altiplano paleoelevations of 1-2 km at 24.5 Ma, 1.5-2.9 km by 11.45 Ma, and modern elevations by ∼6 Ma based on the lightest isotopic compositions observed in Altiplano proxy materials, which are least likely to be influenced by evaporation. These constraints limit total late-Miocene-to-modern uplift to <2.2 km, are more consistent with crustal shortening records, and suggest that plateau uplift may have been more spatially uniform than suggested by previous interpretations of stable isotope proxies.

  9. Two new trans-Andean species of Imparfinis Eigenmann & Norris, 1900 (Siluriformes: Heptapteridae from Colombia

    Directory of Open Access Journals (Sweden)

    Armando Ortega-Lara

    2011-01-01

    Full Text Available Two new species of Imparfinis are described from the trans-Andean region of Colombia. Imparfinis timana is diagnosed by having longer anal fin base (12.4-15.5% in SL, in combination with long adipose fin (24.6-31.3% in SL, 5-6 gill rakers on the first ceratobranchial, 42-43 vertebrae and additional measurements. Imparfinis usmai is distinguished by the combination of first ray of dorsal fin longest, but not projected as a long filament, long adipose fin (21.1-27.0% in SL, maxillary barbel exceeding pelvic-fin base, 39-40 vertebrae, upper caudal-fin lobe pointed and longer than lower lobe, lower lobe rounded, 7-8 gill rakers on the first ceratobranchial, as well as additional measurements. Imparfinis timana is only known from río Guarapas, a small tributary of the upper course of the río Magdalena. Imparfinis usmai is broadly distributed in the upper basin of ríos Cauca and Magdalena, and in the lower Patía river basin. The restricted distribution of I. nemacheir to trans-Andean drainages (Atrato, Magdalena, and Lago de Maracaibo is also discussed.Duas novas espécies do gênero Imparfinis são descritas da região transandina da Colômbia. Imparfinis timana é diagnosticada por possuir as nadadeiras adiposa e anal compridas (24,6-31,3% e 12,4-15,5% no CP, respectivamente, 5-6 rastros branquiais no primeiro ceratobranquial, 42-43 vértebras, além de outros caracteres de morfometria. Imparfinis usmai é diferenciada pela combinação do primeiro raio da nadadeira dorsal longo, mas não projetado como um filamento comprido, nadadeira adiposa longa (21,1-27,0% na CP, barbilhões maxilares ultrapassando a base da nadadeira ventral, 39-40 vértebras, lóbulo superior da nadadeira caudal pontiagudo e mais longo que o lóbulo inferior, lóbulo inferior arredondado, 7-8 rastros branquiais no primeiro ceratobranquial e outros caracteres de morfometria. Imparfinis timana é conhecida somente para o rio Guarapas, pequeno tributário da bacia do alto

  10. Snowpack energy balance analysis using field measurements in an Andean watershed

    Science.gov (United States)

    Stehr, Alejandra

    2014-05-01

    Depending on the relative altitude and ambient temperature, Andean watersheds present important snow coverage during winter season. Snowpack stores significant amount of water which is released to surface runoff and groundwater when solar radiation increases, mainly during the spring and summer season, controlling the shape of the annual hydrograph and affecting the water balance at monthly and shorter scales. Field measurements of snow cover in those areas are difficult to perform due to adverse climatic and topographic conditions. Therefore, it is useful to support the hydrological characterization of watersheds located in the high mountains with models representing runoff from melting, for example, models based on the energy balance of the snowpack. The objective of this work is to characterize and quantify the energy flows that control the accumulation and melting of snow cover, using field measurements. The work was done on the upper Malleco watershed, which is located in the Andes Mountain Range (38°20' - 38°41' S and 71°13' - 71°35' W) and has an area of 27 km2, elevations vary between 900 to 1789 m a.m.s.l. For the calculation of the different the energy balance components, two weather stations were installed in the study area, which recorded data every 15 minutes. The variables measured were: global solar radiation, net radiation, shortwave and longwave radiation, air temperature, relative humidity, wind speed and direction, soil heat flux, precipitation and snow depth. Two analyzes were performed: 1) Energy Balance 2010. Two representative periods of accumulation (1st July to 31st July) and melting (10 September to 10 October) were selected in one of the stations. 2) Energy Balance 2011. Energy balance for a 15 days period of accumulation (July 19 to August 3, 2011) was with the aim of comparing both meteorological stations. In all cases hourly energy fluxes, snow water equivalent and daily snow depth were calculated. The latter was compared with the

  11. Clasificación de yeso mediante imágenes ASTER en la Cordillera Principal Mendocina Gypsum classification based on ASTER images in the Principal Cordillera of Mendoza

    Directory of Open Access Journals (Sweden)

    José F Mescua

    2010-06-01

    Full Text Available Se presenta una metodología para obtener el mapa de distribución de yeso con imágenes satelitales ASTER. Se utilizaron imágenes con nivel de procesamiento ASTERL3A correspondientes a dos áreas de la Cordillera Principal mendocina. La estratigrafía de las áreas de estudio se encuentra compuesta por una espesa sucesión sedimentaria mesozoica, volcanitas cenozoicas y depósitos cuaternarios. Dentro de los depósitos mesozoicos se encuentra la Formación Auquilco, integrada por yeso y anhidrita. El reconocimiento y distribución areal de esta unidad es el objetivo de este trabajo. Se aplicaron dos métodos de procesamiento a las imágenes. Por un lado se utilizó el índice de cuarzo (Qi, uno de los índices de determinación de minerales definidos para el subsistema TIR de ASTER. Este índice puede usarse también para reconocer sulfatos, y en particular yeso, ya que estos minerales proporcionan una respuesta muy baja en el Qi. El segundo método consistió en la aplicación combinada de los cocientes de bandas 4/5 y 7/5. Este método permite identificar al yeso por su elevada respuesta en el cociente 4/5 y baja respuesta en el cociente 7/5. A fin de simplificar la metodología, se generó un nuevo cociente a partir de los dos mencionados: (4/5/(7/5, de manera de destacar el yeso con alta respuesta. A partir del relevamiento de campo se observó que en ambos métodos los errores por exceso fueron más importantes que los errores por defecto, y que los píxeles determinados como yeso erróneamente por cada método son diferentes. Este hecho permite la aplicación de la técnica de "Decision Tree" del programa ENVI 4.2 con el objetivo de eliminar estos errores. En cada una de las imágenes se determinaron los valores de umbral para los píxeles reconocidos como yeso. Luego se generó un "árbol de decisiones" combinando los umbrales de cada imagen, seleccionando en una nueva clase los píxeles determinados como yeso por ambos métodos y

  12. Geographic determinants of gene flow in two sister species of tropical Andean frogs.

    Science.gov (United States)

    Guarnizo, Carlos E; Cannatella, David C

    2014-01-01

    Complex interactions between topographic heterogeneity, climatic and environmental gradients, and thermal niche conservatism are commonly assumed to indicate the degree of biotic diversification in montane regions. Our aim was to investigate factors that disrupt gene flow between populations and to determine if there is evidence of downslope asymmetric migration in highland frogs with wide elevational ranges and thermal niches. We determined the role of putative impediments to gene flow (as measured by least-cost path (LCP) distances, topographic complexity, and elevational range) in promoting genetic divergence between populations of 2 tropical Andean frog sister species (Dendropsophus luddeckei, N = 114; Dendropsophus labialis, N = 74) using causal modeling and multiple matrix regression. Although the effect of geographic features was species specific, elevational range and LCP distances had the strongest effect on gene flow, with mean effect sizes (Mantel r and regression coefficients β), between 5 and 10 times greater than topographic complexity. Even though causal modeling and multiple matrix regression produced congruent results, the latter provided more information on the contribution of each geographic variable. We found moderate support for downslope migration. We conclude that the climatic heterogeneity of the landscape, the elevational distance between populations, and the inability to colonize suboptimal habitats due to thermal niche conservatism influence the magnitude of gene flow. Asymmetric migration, however, seems to be influenced by life history traits. PMID:24336965

  13. Cliffs used as communal roosts by Andean condors protect the birds from weather and predators.

    Directory of Open Access Journals (Sweden)

    Sergio A Lambertucci

    Full Text Available The quality and availability of resources influence the geographical distribution of species. Social species need safe places to rest, meet, exchange information and obtain thermoregulatory benefits, but those places may also serve other important functions that have been overlooked in research. We use a large soaring bird that roosts communally in cliffs, the Andean condor (Vultur gryphus, as a model species to elucidate whether roost locations serve as a refuge from adverse weather conditions (climatic refuge hypothesis, CRH, and/or from predators or anthropogenic disturbances (threats refuge hypothesis, TRH. The CRH predicts that communal roosts will face in the opposite direction from where storms originate, and will be located in climatically stable, low precipitation areas. The TRH predicts that communal roosts will be large, poorly accessible cliffs, located far from human-made constructions. We surveyed cliffs used as communal roosts by condors in northwestern Patagonia, and compared them with alternative non-roosting cliffs to test these predictions at local and regional scales. We conclude that communal roosting places provide refuge against climate and disturbances such as, for instance, the threats of predators (including humans. Thus, it is not only the benefits gained from being aggregated per se, but the characteristics of the place selected for roosting that may both be essential for the survival of the species. This should be considered in management and conservation plans given the current scenario of global climate change and the increase in environmental disturbances.

  14. [Floristic composition and distribution of the Andean subtropical riparian forests of Lules River, Tucuman, Argentina].

    Science.gov (United States)

    Sirombra, Martín G; Mesa, Leticia M

    2010-03-01

    We studied the floristic composition and distribution of the riparian forest of two hydrographical systems in a subtropical Andean region. Using uni and multivariate techniques, we tested the hypotheses that a differentiable riparian forest exists, composed by native vegetation typical of the Yungas phytogeographical province, and that the distribution of vegetation varied significantly with geomorphologic characteristics. Parallel transects along the water courses were used to collect presence-absence data of vegetation in eleven sites. Detrended Correspondence Analysis defined a group of common riparian species for the studied area (Solanum riparium, Phenax laevigatus, Tipuana tipu, Cestrum parqui, Carica quercifolia, Acacia macracantha, Celtis iguanaea, Juglans australis, Pisoniella arborescens, Baccharis salicifolia, Cinnamomum porphyrium and Eugenia uniflora) and identified two reference sites. The distribution of the riparian vegetation varied significantly with the geomorphic characteristics along the studied sites. Riparian habitats were composed by native and exotic species. A distinct riparian flora, different in structure and function from adjacent terrestrial vegetation, could not be identified. Riparian species were similar to the adjacent terrestrial strata. These species would not be limited by the proximity to the river. Anthropogenic impacts were important factors regulating the introduction and increase of exotic vegetation. The lack of regulation of some activities in the zone could cause serious problems in the integrity of this ecosystem.

  15. Human impact on the hydrology of the Andean páramos

    Science.gov (United States)

    Buytaert, Wouter; Célleri, Rolando; De Bièvre, Bert; Cisneros, Felipe; Wyseure, Guido; Deckers, Jozef; Hofstede, Robert

    2006-11-01

    This paper analyses the problems involved in the conservation and management of the hydrological system of the South American páramo. The páramo consists of a collection of neotropical alpine grassland ecosystems covering the upper region of the northern Andes. They play a key role in the hydrology of the continent. Many of the largest tributaries of the Amazon basin have their headwaters in the páramo. It is also the major water source for the Andean highlands and a vast area of arid and semi-arid lowlands, where páramo water is used for domestic, agricultural and industrial consumption, and the generation of hydropower. Recently, the páramo is increasingly used for intensive cattle grazing, cultivation, and pine planting, among others. These activities, as well as global phenomena such as climate change, severely alter the hydrological regime. A review on the state of knowledge of its hydrology is given in a first part. In a second part, the impact of human activities and climate change on the hydrology of the páramo is discussed.

  16. Vicuña conservation and poverty alleviation? Andean communities and international fibre markets

    Directory of Open Access Journals (Sweden)

    Gabriela Lichtenstein

    2009-09-01

    Full Text Available Vicuna (Vicugna vicugna fiber is produced by extremely low-income communities that inhabit the harsh environment of the Andes in Argentina, Chile, Peru and Bolivia. At the other end of the social scale, affluent consumers are willing to pay high prices for vicuna-made accessories and clothes. Vicuna management projects follow the logic of community-based wildlife management. The rationale for seeking to conserve vicuñas through sustainable use is that commercial utilization of the fiber (obtained from live-shorn animals will generate sufficient economic benefits to outweigh the costs of conservation, and contribute to community development and poverty alleviation. However, although conservation efforts have been extremely successful with vicuñas having recovered from the brink of extinction, the socio-economic achievements have thus far proved modest. This paper explores multiple-objective projects that address vicuña conservation and poverty alleviation in Andean countries. In doing so it analyses the tensions that exist between these objectives, as well as the factors that limit a more equitable distribution of benefits among stakeholders. Examples are drawn from vicuna management under common-property in Peru and Bolivia, and vicuna captive management under private property in Argentina. These case studies enable us to illustrate the complex relationship between local communities and the global market, and the importance of community enterprises and supportive government policy in managing a common pool resource.

  17. Forged Under the Sun: Life and Art of Extremophiles from Andean Lakes.

    Science.gov (United States)

    Albarracín, Virginia Helena; Gärtner, Wolfgang; Farias, María Eugenia

    2016-01-01

    High-altitude Andean lakes (HAAL) are a treasure chest for microbiological research in South America. Their indigenous microbial communities are exposed to extremely high UV irradiation and to multiple chemical extremes (Arsenic, high salt content, alkalinity). Microbes are found both, free-living or associated into microbial mats with different degrees of mineralization and lithification, including unique modern stromatolites located at 3570 m above sea level. Characterization of these polyextremophilic microbes began only recently, employing morphological and phylogenetic methods as well as high-throughput sequencing and proteomics approach. Aside from providing a general overview on microbial communities, special attention is given to various survival strategies; HAAL's microbes present a complex system of shared genetic and physiological mechanisms (UV-resistome) based on UV photoreceptors and stress sensors with their corresponding response regulators, UV avoidance and protection strategies, damage tolerance and UV damage repair. Molecular information will be provided for what is, so far the most studied HAAL molecule, a CPD-Class I photolyase from Acinetobacter Ver3 (Laguna Verde, 4400 m). This work further proposes some strategies that make an appeal for the preservation of HAAL, a highly fragile environment that offers promising and ample research possibilities. PMID:26647770

  18. Hydrophilic antioxidants from Andean tomato landraces assessed by their bioactivities in vitro and in vivo.

    Science.gov (United States)

    Di Paola Naranjo, Romina D; Otaiza, Santiago; Saragusti, Alejandra C; Baroni, Veronica; Carranza, Andrea Del V; Peralta, Iris E; Valle, Estela M; Carrari, Fernando; Asis, Ramón

    2016-09-01

    Potential nutraceutical properties of hydrophilic antioxidants in fruits of tomato landraces collected in Andean valleys were characterised. Antioxidant metabolites were measured by HPLC-DAD-MS/MS in mature fruits and their biological activities were assessed by in vitro and in vivo methods. In vitro antioxidant capacities were established by TEAC and FRAP methods. For in vivo biological activities we used a procedure based on Caenorhabditis elegans subjected to thermal stress. In addition, Saccharomyces cerevisiae was also used as a rapid screening system to evaluate tomato antioxidant capacity. All tomato accessions displayed significant differences regarding metabolic composition, biological activity and antioxidant capacity. Metabolite composition was associated with geographical origin and fruit size. Antioxidant activities showed significant association with phenolic compounds, such as caffeoylquinic acids, ferulic acid-O-hexosides and rutin. Combination of in vitro and in vivo methods applied here allowed evaluation of the variability in nutraceutical properties of tomato landraces, which could be applied to other fruits or food products. PMID:27041310

  19. Gut Microbiome of an 11th Century A.D. Pre-Columbian Andean Mummy.

    Directory of Open Access Journals (Sweden)

    Tasha M Santiago-Rodriguez

    Full Text Available The process of natural mummification is a rare and unique process from which little is known about the resulting microbial community structure. In the present study, we characterized the microbiome of paleofeces, and ascending, transverse and descending colon of an 11th century A.D. pre-Columbian Andean mummy by 16S rRNA gene high-throughput sequencing and metagenomics. Firmicutes were the most abundant bacterial group, with Clostridium spp. comprising up to 96.2% of the mummified gut, while Turicibacter spp. represented 89.2% of the bacteria identified in the paleofeces. Microbiome profile of the paleofeces was unique when compared to previously characterized coprolites that did not undergo natural mummification. We identified DNA sequences homologous to Clostridium botulinum, Trypanosoma cruzi and human papillomaviruses (HPVs. Unexpectedly, putative antibiotic-resistance genes including beta-lactamases, penicillin-binding proteins, resistance to fosfomycin, chloramphenicol, aminoglycosides, macrolides, sulfa, quinolones, tetracycline and vancomycin, and multi-drug transporters, were also identified. The presence of putative antibiotic-resistance genes suggests that resistance may not necessarily be associated with a selective pressure of antibiotics or contact with European cultures. Identification of pathogens and antibiotic-resistance genes in ancient human specimens will aid in the understanding of the evolution of pathogens as a way to treat and prevent diseases caused by bacteria, microbial eukaryotes and viruses.

  20. Evaluation of metasomatic changes in an interlayered blueschist-greenschist sequence (Coastal Cordillera, Chile) by combining geochemical data with equilibrium assemblage diagrams

    Science.gov (United States)

    Halama, Ralf; Konrad-Schmolke, Matthias

    2014-05-01

    In the Coastal Cordillera of Central Chile, a spectacular sequence of interlayered blueschists and greenschists occurs in coastal outcrops near Pichilemu. Three explanations are generally proposed to interpret the interlayering of metamorphic rocks that represent distinct metamorphic facies: 1. Differences in the pressure-temperature (P-T) conditions of equilibration and late-stage tectonic juxtaposition, 2. Chemical differences between the layers inherited from the protolith, and 3. Differences in the degree of metasomatic overprint during metamorphism. Investigations of such interlayered sequences can shed light on the mobility of elements and fluid-rock interaction during metamorphism. To identify the processes responsible for interlayering, geochemical analyses were combined with petrologic investigations involving the calculation of isothermal and isobaric binary phase diagrams using the THERIAK-DOMINO [1] software. Major mineral phases in blueschist and greenschist layers are amphibole, white mica, chlorite, and albite with subordinate amounts of titanite, epidote, hematite and apatite. The mineralogy of blueschist and greenschist layers is similar, albeit the modal proportions differ, causing the distinct colouring. Peak P-T conditions of blueschists reach 370±20 °C at 10±1 kbar [2]. The layering on a cm-to-dm scale and the similar mineralogy suggest that both blueschist and greenschist layers experienced a similar P-T evolution. For adjacent blueschist-greenschist pairs, blueschists have consistently higher Si and Na contents, whereas greenschists are relatively enriched in Al, Mg and total Fe. However, the observed major element geochemical trends are inconsistent with magmatic differentiation. For several blueschist-greenschist pairs, ratios of incompatible trace elements, which are indicative of the protolith composition and considered as relatively immobile during low-T metamorphism (Th/Yb, Nb/Yb), are near identical. These features point to

  1. Direct and indirect effects of glaciers on aquatic biodiversity in high Andean peatlands.

    Science.gov (United States)

    Quenta, Estefania; Molina-Rodriguez, Jorge; Gonzales, Karina; Rebaudo, François; Casas, Jérôme; Jacobsen, Dean; Dangles, Olivier

    2016-09-01

    The rapid melting of glacier cover is one of the most obvious impacts of climate change on alpine ecosystems and biodiversity. Our understanding of the impact of a decrease in glacier runoff on aquatic biodiversity is currently based on the 'glacier-heterogeneity-diversity' paradigm, according to which there is high α-diversity at intermediate levels of glacial influence due to the high degree of environmental heterogeneity caused by glacier water. This α-diversity pattern ge