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Sample records for basin northern chile

  1. Geomorphological characterization of endorheic basins in northern Chile

    Science.gov (United States)

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

    2011-12-01

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

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

    Science.gov (United States)

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

    2004-12-01

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

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

    OpenAIRE

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

    2009-01-01

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

  4. Deep seismic structure of the Atacama basin, northern Chile

    Science.gov (United States)

    Schurr, B.; Rietbrock, A.

    2004-06-01

    The Atacama basin is a prominent morphological anomaly in the Central Andean forearc. 3D seismic structure beneath the depression and its surroundings has been determined from local earthquake tomography. Depth maps of P-wave velocity and attenuation (1/Qp) through the lithosphere reveal a rheologically strong (high Qp and vp) lithospheric block beneath the basin, surrounded by weak regions (low Qp and vp) beneath Pre- and Western Cordilleras. The anomalous lithospheric structure appears to bar hot asthenospheric mantle from penetrating trenchward, and hence causes the volcanic front to be deflected by the Salar de Atacama basin. The cold block may also influence the thermal structure of the subducted slab causing reduced Benioff seismicity and less hydration of mantle rocks evident from reduced vp/vs ratios. Seismic data are hard to reconcile with extension and lithospheric thinning as a mechanism for subsidence of the basin. Instead, high strength of the Atacama lithospheric block may contribute to basin formation by focussing deformation and uplift along the block's weak edges.

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

    Science.gov (United States)

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

    2009-06-01

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

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

    Science.gov (United States)

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

    2007-02-01

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

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

    Science.gov (United States)

    Breitkreuz, Christoph

    1991-11-01

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

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

    Directory of Open Access Journals (Sweden)

    Nelson Muñoz

    2002-07-01

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

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

    Science.gov (United States)

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

    1990-01-01

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

  10. Isotope hydrology in northern Chile

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Nelson Muñoz; Reynaldo Charrier; Teresa Jordan

    2002-01-01

    ABSTRACT A reinterpretation of the structural style on the eastern Cordillera Domeyko and the adjacent Salar de Atacama Basin reveals the existence of west-dipping, high-angle, thrust-faults extending below the Cordillera Domeyko and Cordón de Lila, resulting from inversion of Cretaceous extensional faults, that transferred west-ward their displacement into the cover, generating fault-propagation and detachment folds. The most conspicuous of these structures is the Cordillera de la Sal. Contr...

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

    OpenAIRE

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

    2005-01-01

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

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

    Science.gov (United States)

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

    2005-04-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

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

    2013-01-01

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

  16. Geometry of the inverted Cretaceous Chañarcillo Basin based on 2-D gravity and field data. An approach to the structure of the western Central Andes of northern Chile

    Directory of Open Access Journals (Sweden)

    F. Martínez

    2015-08-01

    Full Text Available This paper discusses an integrated approach that provides new ideas about the structural geometry of the NNE-striking, Cretaceous Chañarcillo Basin located along the eastern Coastal Cordillera in the western Central Andes of northern Chile (27–28° S. The results obtained from the integration of two transverse (E–W gravity profiles with previous geological information, show that the architecture of this basin is defined by a large NNE–SSE-trending and east-vergent anticline ("Tierra Amarilla Anticlinorium", which is related to the positive reactivation of a former Cretaceous normal fault (Elisa de Bordos Master Fault. Moreover, intercalations of high and low gravity anomalies and steep gravity gradients reveal a set of buried, west-tilted half-grabens associated with a synthetic normal fault pattern. These results, together with the uplift and folding style of the Cretaceous syn-rift recognized within the basin, suggest that their complete structural geometry could be explained by an inverted fault system linked to the shortening of pre-existing Cretaceous normal fault systems. Ages of the synorogenic deposits exposed unconformably over the frontal limb of the Tierra Amarilla Anticlinorium confirm a Late Cretaceous age for the Andean deformation and tectonic inversion of the basin.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-06-01

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

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

    OpenAIRE

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

    2007-01-01

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

  19. Subduction zone guided waves in Northern Chile

    Science.gov (United States)

    Garth, Thomas; Rietbrock, Andreas

    2016-04-01

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

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

    OpenAIRE

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

    2011-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Geoffrey May

    2005-01-01

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

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

    OpenAIRE

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

    2004-01-01

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

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

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    Jorge E. Clavero R.

    2004-12-01

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

  4. Isotopic evolution of aqueous sulphate in northern Chile water

    International Nuclear Information System (INIS)

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

  5. Palaeoindian occupation of the Atacama Desert, northern Chile

    Science.gov (United States)

    Grosjean, Martin; Núñez, Lautaro; Cartajena, Isabel

    2005-10-01

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

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

    Directory of Open Access Journals (Sweden)

    J. A. Díaz-Ochoa

    2010-07-01

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

  7. Site testing for the VLT in Northern Chile

    Science.gov (United States)

    Woltjer, L.

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

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

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    Mónica E Barros

    2014-11-01

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

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

    Directory of Open Access Journals (Sweden)

    Héctor A. Vargas

    2011-12-01

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

  10. Chile.

    Science.gov (United States)

    1988-09-01

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

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

    Directory of Open Access Journals (Sweden)

    Adrian Hartley

    2001-07-01

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

  12. Apacheta, a new geothermal prospect in Northern Chile

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-05-24

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

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

    Science.gov (United States)

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

    1985-01-01

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

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

    Science.gov (United States)

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

    2010-05-01

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

  15. Megafans of the Northern Kalahari Basin

    Science.gov (United States)

    Wilkinson, M. J.; Miller, R. McG.; Eckardt, F.; Kreslavsky, M. A.

    2016-01-01

    We identify eleven megafans (partial cones of fluvial sediment, >80 km radius) in the northern Kalahari Basin, using several criteria based on VIS and IR remotely sensed data and SRTM-based surface morphology reconstructions. Two other features meet fewer criteria of the form which we class as possible megafans. The northern Kalahari megafans are located in a 1700 km arc around the southern and eastern flanks of the Angola's Bié Plateau, from northern Namibia through northwest Botswana to western Zambia. Three lie in the Owambo subbasin centered on the Etosha Pan, three in the relatively small Okavango rift depression, and five in the Upper Zambezi basin. The population includes the well-known Okavango megafan (150 km), Namibia's Cubango megafan, the largest megafan in the region (350 km long), and the largest nested group (the five major contiguous megafans on the west slopes of the upper Zambezi Valley). We use new, SRTM-based topographic roughness data to discriminate various depositional surfaces within the flat N. Kalahari landscapes. We introduce the concepts of divide megafans, derived megafans, and fan-margin rivers. Conclusions. (i) Eleven megafan cones total an area of 190,000 sq km. (ii) Different controls on megafan size operate in the three component basins: in the Okavango rift structural controls become the prime constraint on megafan length by controlling basin dimensions. Megafans in the other les constricted basins appear to conform to classic relationships fan area, slope, and feeder-basin area. (iii) Active fans occupy the Okavango rift depression with one in the Owambo basin. The rest of the population are relict but recently active fans (surfaces are relict with respect to activity by the feeder river). (iv) Avulsive behavior of the formative river-axiomatic for the evolution of megafans-has resulted in repeated rearrangements of regional drainage, with likely effects in the study area well back into the Neogene. Divide megafans comprise the

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

    OpenAIRE

    Tom Eulenfeld [Richter; Günter Asch; Rainer Kind

    2011-01-01

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

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

    Science.gov (United States)

    Araya, Juan Francisco

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Science.gov (United States)

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

    2013-12-01

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

  20. Large slope instabilities in Northern Chile and Southern Peru

    Science.gov (United States)

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

    2014-05-01

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

  1. Assessing groundwater recharge in an Andean closed basin using isotopic characterization and a rainfall-runoff model: Salar del Huasco basin, Chile

    Science.gov (United States)

    Uribe, Javier; Muñoz, José F.; Gironás, Jorge; Oyarzún, Ricardo; Aguirre, Evelyn; Aravena, Ramón

    2015-11-01

    Closed basins are catchments whose drainage networks converge to lakes, salt flats or alluvial plains. Salt flats in the closed basins in arid northern Chile are extremely important ecological niches. The Salar del Huasco, one of these salt flats located in the high plateau (Altiplano), is a Ramsar site located in a national park and is composed of a wetland ecosystem rich in biodiversity. The proper management of the groundwater, which is essential for the wetland function, requires accurate estimates of recharge in the Salar del Huasco basin. This study quantifies the spatio-temporal distribution of the recharge, through combined use of isotopic characterization of the different components of the water cycle and a rainfall-runoff model. The use of both methodologies aids the understanding of hydrological behavior of the basin and enabled estimation of a long-term average recharge of 22 mm/yr (i.e., 15 % of the annual rainfall). Recharge has a high spatial variability, controlled by the geological and hydrometeorological characteristics of the basin, and a high interannual variability, with values ranging from 18 to 26 mm/yr. The isotopic approach allowed not only the definition of the conceptual model used in the hydrological model, but also eliminated the possibility of a hydrogeological connection between the aquifer of the Salar del Huasco basin and the aquifer that feeds the springs of the nearby town of Pica. This potential connection has been an issue of great interest to agriculture and tourism activities in the region.

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

    OpenAIRE

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

    2013-01-01

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

  3. Integrated Water Resource Management and Energy Requirements for Water Supply in the Copiapó River Basin, Chile

    Directory of Open Access Journals (Sweden)

    Francisco Suárez

    2014-08-01

    Full Text Available Population and industry growth in dry climates are fully tied to significant increase in water and energy demands. Because water affects many economic, social and environmental aspects, an interdisciplinary approach is needed to solve current and future water scarcity problems, and to minimize energy requirements in water production. Such a task requires integrated water modeling tools able to couple surface water and groundwater, which allow for managing complex basins where multiple stakeholders and water users face an intense competition for limited freshwater resources. This work develops an integrated water resource management model to investigate the water-energy nexus in reducing water stress in the Copiapó River basin, an arid, highly vulnerable basin in northern Chile. The model was utilized to characterize groundwater and surface water resources, and water demand and uses. Different management scenarios were evaluated to estimate future resource availability, and compared in terms of energy requirements and costs for desalinating seawater to eliminate the corresponding water deficit. Results show a basin facing a very complex future unless measures are adopted. When a 30% uniform reduction of water consumption is achieved, 70 GWh over the next 30 years are required to provide the energy needed to increase the available water through seawater desalination. In arid basins, this energy could be supplied by solar energy, thus addressing water shortage problems through integrated water resource management combined with new technologies of water production driven by renewable energy sources.

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

    Science.gov (United States)

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

    2016-05-01

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

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

    Directory of Open Access Journals (Sweden)

    Alvial I.E.

    2013-02-01

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

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

    Science.gov (United States)

    Díaz, Daniel; Brasse, Heinrich; Ticona, Faustino

    2012-03-01

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

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

    OpenAIRE

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

    2012-01-01

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

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

    OpenAIRE

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

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Juan Francisco Araya

    2015-03-01

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

  10. Uranium deposits: northern Denver Julesburg basin, Colorado

    International Nuclear Information System (INIS)

    The Fox Hills Sandstone and the Laramie Formation (Upper Cretaceous) are the host rocks for uranium deposits in Weld County, northern Denver Julesburg basin, Colorado. The uranium deposits discovered in the Grover and Sand Creek areas occur in well-defined north--south trending channel sandstones of the Laramie Formation whereas the sandstone channel in the upper part of the Fox Hills Sandstone trends east--west. Mineralization was localized where the lithology was favorable for uranium accumulation. Exploration was guided by log interpretation methods similar to those proposed by Bruce Rubin for the Powder River basin, Wyoming, because alteration could not be readily identified in drilling samples. The uranium host rocks consist of medium- to fine-grained carbonaceous, feldspathic fluvial channel sandstones. The uranium deposits consist of simple to stacked roll fronts. Reserve estimates for the deposits are: (1) Grover 1,007,000 lbs with an average grade of 0.14 percent eU3O8,2) Sand Creek 154,000 lbs with an average grade of 0.08 percent eU3O8, and 3) The Pawnee deposit 1,060,000 lbs with an average grade of 0.07 percent eU3O8. The configuration of the geochemical cells in the Grover and Sand Creek sandstones indicate that uraniferous fluids moved northward whereas in the Pawnee sandstone of the Fox Hills uraniferous fluids moved southward. Precipitation of uranium in the frontal zone probably was caused by downdip migration of oxygcnated groundwater high in uranium content moving through a favorable highly carbonaceous and pyritic host sandstone

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

    OpenAIRE

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

    2006-01-01

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

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

    OpenAIRE

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

    2011-01-01

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

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

    OpenAIRE

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

    2009-01-01

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

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

    Science.gov (United States)

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

    2013-04-01

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

  15. Chile.

    Science.gov (United States)

    1992-05-01

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

  16. Spatial and temporal constraints on regional-scale groundwater flow in the Pampa del Tamarugal Basin, Atacama Desert, Chile

    Science.gov (United States)

    Jayne, Richard S.; Pollyea, Ryan M.; Dodd, Justin P.; Olson, Elizabeth J.; Swanson, Susan K.

    2016-08-01

    Aquifers within the Pampa del Tamarugal Basin (Atacama Desert, northern Chile) are the sole source of water for the coastal city of Iquique and the economically important mining industry. Despite this, the regional groundwater system remains poorly understood. Although it is widely accepted that aquifer recharge originates as precipitation in the Altiplano and Andean Cordillera to the east, there remains debate on whether recharge is driven primarily by near-surface groundwater flow in response to periodic flood events or by basal groundwater flux through deep-seated basin fractures. In addressing this debate, the present study quantifies spatial and temporal variability in regional-scale groundwater flow paths at 20.5°S latitude by combining a two-dimensional model of groundwater and heat flow with field observations and δ18O isotope values in surface water and groundwater. Results suggest that both previously proposed aquifer recharge mechanisms are likely influencing aquifers within the Pampa del Tamarugal Basin; however, each mechanism is operating on different spatial and temporal scales. Storm-driven flood events in the Altiplano readily transmit groundwater to the eastern Pampa del Tamarugal Basin through near-surface groundwater flow on short time scales, e.g., 100-101 years, but these effects are likely isolated to aquifers in the eastern third of the basin. In addition, this study illustrates a physical mechanism for groundwater originating in the eastern highlands to recharge aquifers and salars in the western Pampa del Tamarugal Basin over timescales of 104-105 years.

  17. Evaluation of the hydrogeological interconnection between the Salar de Maricunga and the Piedra Pomez basins, Atacama Region, Chile; An isotope and geochemical approach

    International Nuclear Information System (INIS)

    Groundwater is the main water source for the mining industry in the Altiplano of northern Chile. Groundwater also plays a significant role as a water source for lagoons, wetlands and salares, which are important ecosystems for animal life and vegetation communities that exist in this arid region. The rational use and protection of the groundwater resource requires a good understanding of the aquifer systems. One of the key components in the assessment of water resources in Northern Chile, is the hydrogeological interconnection between basins. During the last three years, as part of a major hydrogeological project, Sernageomin has been working in the Altiplano of the Atacama region (Iriarte et al., 1998; Iriarte, 1999; Venegas et al., 2000; Santibanez, in prep.). This study included the evaluation of the geometry and groundwater potential of the aquifers and the chemical characterization of the surface and groundwater. Part of this study has focused on the Salar de Maricunga and the Campo de Piedra Pomez basins, due to an increasing demand for groundwater resources in this area by the mining industry. This paper discusses the use of isotope and geochemical tools that were used to evaluate the hydrogeological interconnection between the Salar de Maricunga and the Piedra Pomez basins. The geological and hydrogeological framework of this work is discussed in detail by Iriarte (1999) (au)

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

    Directory of Open Access Journals (Sweden)

    Monia Procesi

    2014-08-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

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

    2004-04-01

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

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

    OpenAIRE

    Juan Francisco Araya; Ricardo Catalán

    2014-01-01

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

  2. Chile.

    Science.gov (United States)

    1986-04-01

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

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

    OpenAIRE

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

    1998-01-01

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

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

    Science.gov (United States)

    Collado, Gonzalo A

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Héctor A. Vargas

    2014-03-01

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

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

    OpenAIRE

    2014-01-01

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

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

    Science.gov (United States)

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

    2011-12-01

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

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

    Science.gov (United States)

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

    2001-12-01

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

  10. Ecological aspects of nematode parasites of introduced salmonids from Valdivia river basin, Chile

    Directory of Open Access Journals (Sweden)

    Patricio Torres

    1991-03-01

    Full Text Available Between 1986 and 1987 fishes distributed among the following species introduced in Chile, and from different sectors of the Valdivia river basin (39º30' - 40º00', 73º30' - 71º45'W, were examined: 348 Salmo trutta, 242 Salmo gairdneri, 24 Cyprinus carpio and 52 Gambusia affinis holbrooki. The presence of Camallanus corderoi and Contracaecum sp. in S. gairdneri and of C. corderoi in S. trutta is recorded in Chile for the first time. Cyprinus carpio and G. a. holbrooki did not present infections by nematodes. The prevalence and mean intensity of the infections by nematodes presented significant differences among some sectors of the Valdivia river basin. In general, the prevalence and intensity of the infections by C. corderoi were greater than those by Contracaecum sp. The infections in S. gairdneri were higher than in S. trutta. The sex of the hosts had no influence on the prevalence and intensity of the infections by both nematodes. The length of the hosts did have an influence, except in the case of the infections by Contracaecum sp. in S, gairdneri. The infrapopulations of both nematode species showed over dispersion in most cases. The diet of the examined salmonids suggests that they would become infected principally throught the consuption of autochthonous fishes.

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

    Directory of Open Access Journals (Sweden)

    Héctor A. Vargas

    2011-06-01

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

  12. Climate change adaptation in a highly urbanized snowmelt dominated basin in Central Chile

    Science.gov (United States)

    Vicuna, S.; Bustos, E.; Merino, P.; Henriquez Dole, L. E.; Jansen, S.; Gil, M.; Ocampo, A.; Poblete, D.; Tosoni, D.; Meza, F. J.; Donoso, G.; Melo, O.

    2015-12-01

    The Maipo river basin holds 40% of Chile's total population and produces almost half of the country's Gross Domestic Product. The basin is located in the semiarid and snowmelt dominated central region of the country and, aside from the typical pressures of growth in developing country basins, the Maipo river basin faces climate change impacts associated with a reduction in total runoff and changes in its seasonality. Surface water is the main water source for human settlements, natural ecosystems, and economic activities including agriculture, mining and hydropower production. In 2012 a research project, called MAPA (Maipo Plan de Adaptacion), began with the objective of articulating a climate variability and climate change adaptation plan for the Maipo river basin. The project engaged at the beginning a group of relevant water and land use stakeholders which allowed for a good representation of critical aspects of an adaptation plan such as the definition of objectives and performance indicators, future land use scenarios, modeling of the different components of the system and design of adaptation strategies. The presentation will highlight the main results of the research project with a special focus on the upper catchments of the basin. These results include the assessment of impacts associated with future climate and land use scenarios on key components of the hydrologic cycle including snowmelt and glacier contribution to runoff and subsequent impacts on water availability for the operation of hydropower facilities, satisfaction of instream (recreation and aquatic ecosystem) uses and provision of water for the city of Santiago (7 million people) and to irrigate more than 100,000 hectares of high value crops. The integrative approach followed in this project including different perspectives on the use of water in the basin provides a good opportunity to test the varying degree of impacts that could be associated with a given future scenario and also understand

  13. Persistent toxic substances in soils and waters along an altitudinal gradient in the Laja River Basin, Central Southern Chile.

    Science.gov (United States)

    Barra, Ricardo; Popp, Peter; Quiroz, Roberto; Bauer, Coretta; Cid, Hernan; von Tümpling, Wolf

    2005-02-01

    In this study the levels and distribution of some persistent toxic substances (PTS) were investigated in soils, superficial water, and snow along an altitudinal gradient in the Laja River Basin (South Central Chile). The principal objective was to establish the basin's contamination status. The working hypothesis was that PTS levels and distribution in the basin are dependent on the degree of anthropogenic intervention. Fifteen PAHs, seven PCBs congeners, and three organochlorine pesticides were studied in superficial soil and water samples obtained along the altitudinal gradient and from a coastal reference station (Lleu-Lleu River). Soil samples were extracted using accelerated solvent extraction with acetone/cyclohexane (1:1) for PAHs and organochlorine compounds. Contaminants were extracted from water and snow samples by liquid-liquid extraction (LLE). PAH and organochlorine compound quantification was carried out by HPLC with fluorescence detection and GC-MS, respectively. PCBs in soils presented four different profiles in the altitudinal gradient, mainly determined by their chlorination degree; these profiles were not observed for the chlorinated pesticides. In general, the detected levels for the analyzed compounds were low for soils when compared with soil data from other remote areas of the world. Higher summation operator PAHs levels in soils were found in the station located at 227 masl (4243 ng g-1 TOC), in a forestry area and near a timber industry, where detected levels were up to eight times higher than the other sampling sites. In general, PAH levels and distribution seems to be dependent on local conditions. No pesticides were detected in surface waters. However, congeners of PCBs were detected in almost all sampling stations with the highest levels being found in Laja Lake waters, where 1.1 ng/l were observed. This concentration is two times higher than values reported for polluted lakes in the Northern Hemisphere. The presence of organochlorine

  14. Northern Rivers Basins human health monitoring program : report

    Energy Technology Data Exchange (ETDEWEB)

    Gabos, S. [Alberta Health, Edmonton, AB (Canada). Health Surveillance

    1999-04-01

    The Northern River Basins Human Health Monitoring Program was established in 1994 to investigate the possible relationships between various environmental risk factors and the health of northern residents in the province. This report presents the initial analysis of the health program and examines the differences in health outcomes across the province and compares the Northern Rivers Basin Study (NRBS) area with the other areas of the province. A series of maps and graphs showed the prevalence of certain diseases and disorders within the Peace and Athabasca river basins. The focus of the report was on reproductive health, congenital anomalies, respiratory ailments, circulatory diseases, gastrointestinal disorders, endocrine and metabolic disorders, and neurocognitive disorders. The study showed that compared to other areas of the province, the NRBS area had higher incidences of endometriosis, selected congenital anomalies, bronchitis, pneumonia, peptic ulcers and epilepsy. There were three potential exposure pathways to environmental contaminants. These were through ingestion of water or food, inhalation of air and through dermal exposure. refs., tabs., figs.

  15. 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.

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Felipe Méndez-Abarca

    2012-06-01

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

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

    OpenAIRE

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

    2016-01-01

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

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

    OpenAIRE

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

    2008-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-11-15

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

  2. The tomato borer, Tuta absoluta, invading the Mediterranean Basin, originates from a single introduction from Central Chile.

    Science.gov (United States)

    Guillemaud, Thomas; Blin, Aurélie; Le Goff, Isabelle; Desneux, Nicolas; Reyes, Maritza; Tabone, Elisabeth; Tsagkarakou, Anastasia; Niño, Laura; Lombaert, Eric

    2015-01-01

    The Lepidopteran pest of tomato, Tuta absoluta, is native to South America and is invasive in the Mediterranean basin. The species' routes of invasion were investigated. The genetic variability of samples collected in South America, Europe, Africa and Middle East was analyzed using microsatellite markers to infer precisely the source of the invasive populations and to test the hypothesis of a single versus multiple introductions into the old world continents. This analysis provides strong evidence that the origin of the invading populations was unique and was close to or in Chile, and probably in Central Chile near the town of Talca in the district of Maule. PMID:25667134

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

    Science.gov (United States)

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

    2007-10-01

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

  4. Helminth parasites of freshwater fishes, Nazas River basin, northern Mexico

    Directory of Open Access Journals (Sweden)

    León, G. Pérez-Ponce

    2010-01-01

    Full Text Available This paper represents the first study of the helminth parasites of freshwater fishes from the Nazas River basinin northern Mexico. Between July 2005 and December 2008, 906 individual fish were collected and examined for helminthparasites in 23 localities along the river basin. Twenty-three species of fish were examined as a part of this inventory work.In total, 41 helminth species were identified: 19 monogeneans, 10 digeneans, seven cestodes, one acanthocephalan, andfour nematodes. The biogeographical implications of our findings are briefly discussed.

  5. Plantation Forestry and Peak Flow Responses in Experimental Catchments and Large River Basins in Chile

    Science.gov (United States)

    Iroume, A.; Huber, A.

    2007-05-01

    Land use changes are inextricably linked to water resources and the consequences of such changes are a problem faced by water managers and governments across the world. This particular study considers the impact of changes in plantation forest cover on the hydrological response, with a specific focus on the issue of peak flow conditions and variation. The research still in progress is focused in small catchments and large river basins of Chile. The analysis of the data and the preparation of this document were carried out within the framework of the INCO- CT2004-510739 EPIC FORCE Project. EPIC FORCE aims to improve the integrated management of forest and water resources at the river basin scale through the development of policies based on sound science, focusing on extreme rainfall/snowmelt events. The focus areas are four Latin American countries (Costa Rica, Ecuador, Chile and Argentina.), which represent a range of humid forest and rainfall/snowmelt regimes with major flood and erosion problems and which suffer from a lack of integrated water and forest policies. Much of the controversy surrounding changes in peak flows following forest treatment arises from uncertainty over the response from different sizes of storms; whilst most studies agree that mean peak flow generally increases (even for only a short period) in the post harvesting period, there have been a number of different conclusions regarding influence of forest cover on peak flows from small storms compared with the flows from large events. In Chile, this research is been carried out in experimental catchments (less than 1 km2) and in large river basins (greater than 94 and up to 1,545 km2). Results from La Reina (34.4 ha), where peak flows from the pre-harvesting period (years 1997 to 1999, plantation of Pinus radiata established in 1977 covering the 79.5% of the area) were compared with those from the post- harvesting period (plantation clearcut between end of 1999 and first months of 2000 and

  6. An Early Cretaceous volcanic arc/marginal basin transition zone, Peninsula hardy, southernmost Chile

    Science.gov (United States)

    Miller, Christopher A.; Barton, Michael; Hanson, Richard E.; Fleming, Thomas H.

    1994-10-01

    The Hardy Formation represents a latest Jurassic-Early Cretaceous volcanic arc that was located along the Pacific margin of southern South America. It was separated from the continent by a marginal basin floored by portions of an ophiolite sequence (the Rocas Verdes ophiolites). The transition between the arc and marginal basin occurs on Peninsula Hardy, southernmost Chile, where there is a lateral facies transition from arc deposits of the Hardy Formation into proximal marginal basin fill of the Yahgan Formation. Interfingering of arc and marginal basin sequences demonstrates that subduction-related arc magmatism was concurrent with marginal basin formation. The lateral facies transition is reflected in the geochemistry of volcanic rocks from the Hardy and Yahgan formations. Basalts, andesites and dacites of the arc sequence follow a calc-alkaline differentiation trend whereas basalts from the marginal basin follow a tholeiitic differentiation trend. Estimates of temperature and oxygen fugacity for crystallization of the arc andesites are similar to values reported for other calc-alkaline andesites. It is suggested that water activity influenced the early or late crystallization of Ti-magnetite and this controlled the style of differentiation of the magmas erupted on Peninsula Hardy. Magmas with high water contents evolved along the calc-alkaline differentiation trend whereas those with low water contents evolved along the tholeiitic differentiation trend. Some rhyolites are differentiated from the calc-alkaline andesites and dacites, but most appear to be the products of crustal anatexis on the basis of trace-element evidence. The arc basalts and some marginal basin basalts show relative enrichment in LILE, relative depletion in HFSE, and enrichment in LREE. Other marginal basin basalts are LREE depleted and show small relative depletions in HFSE. Basalts with both calc-alkaline and tholeiitic affinities can also be recognized in the Rocas Verdes ophiolites

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

    Science.gov (United States)

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

    2010-12-01

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

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

    Science.gov (United States)

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

    2005-10-01

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

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

    Science.gov (United States)

    Oliveira, R E; Neves, W A

    2015-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Sheila Dorsey Vinton

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

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

    Science.gov (United States)

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

    2016-07-01

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

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

    Science.gov (United States)

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

    2014-12-01

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

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

    Science.gov (United States)

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

    2009-01-01

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

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

    Science.gov (United States)

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

    2007-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Juan Francisco Araya

    2014-04-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

  17. Three-dimensional seismo-tectonics in the Po Valley basin, Northern Italy

    NARCIS (Netherlands)

    Turrini, Claudio; Angeloni, Pamela; Lacombe, Olivier; Ponton, Maurizio; Roure, François

    2015-01-01

    The Po Valley (Northern Italy) is a composite foreland-foredeep basin caught in between the Southern Alps and Northern Apennine mountain belts. By integrating the 3D structural model of the region with the public earthquake dataset, the seismo-tectonics of the basin is shown at different scales of o

  18. The characteristics of ginger-like rock and its geological significance in Northern Zhungeer basin

    International Nuclear Information System (INIS)

    The author studies the characteristics of ginger-like stratum and its genesis in northern Zhungeer basin. There are many ginger-like strata of Tertiary-Quaternary exist in northern Zhungeer basin. It shows a good prospect for the formation of Tertiary sandstone type Uranium deposit which can be leached in-situ

  19. 800,000-Year Record of Plate Boundary Earthquakes in the Atacama Desert, Northern Chile

    Science.gov (United States)

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

    2010-12-01

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

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

    Science.gov (United States)

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

    2012-12-01

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

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

    Science.gov (United States)

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

    2005-08-01

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

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

    Science.gov (United States)

    Breitkreuz, Christoph; Van Schmus, W. R.

    1996-11-01

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

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

    Science.gov (United States)

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

    2014-12-01

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

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

    Science.gov (United States)

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

    2012-04-01

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

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

    Science.gov (United States)

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

    2011-02-01

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

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Directory of Open Access Journals (Sweden)

    CECILIA DEMERGASSO

    2003-09-01

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

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

    Directory of Open Access Journals (Sweden)

    Héctor A. Vargas

    2011-06-01

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

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

    OpenAIRE

    Pablo M Rojas

    2014-01-01

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

  10. 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 ...

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

    Directory of Open Access Journals (Sweden)

    González Christian R

    2000-01-01

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

  12. Regional Fluid Flow and Basin Modeling in Northern Alaska

    Science.gov (United States)

    Kelley, Karen D., (Edited By)

    2007-01-01

    INTRODUCTION The foothills of the Brooks Range contain an enormous accumulation of zinc (Zn) in the form of zinc sulfide and barium (Ba) in the form of barite in Carboniferous shale, chert, and mudstone. Most of the resources and reserves of Zn occur in the Red Dog deposit and others in the Red Dog district; these resources and reserves surpass those of most deposits worldwide in terms of size and grade. In addition to zinc and lead sulfides (which contain silver, Ag) and barite, correlative strata host phosphate deposits. Furthermore, prolific hydrocarbon source rocks of Carboniferous and Triassic to Early Jurassic age generated considerable amounts of petroleum that may have contributed to the world-class petroleum resources of the North Slope. Deposits of Zn-Pb-Ag or barite as large as those in the Brooks Range are very rare on a global basis and, accordingly, multiple coincident favorable factors must be invoked to explain their origins. To improve our understanding of these factors and to contribute to more effective assessments of resources in sedimentary basins of northern Alaska and throughout the world, the Mineral Resources Program and the Energy Resources Program of the U.S. Geological Survey (USGS) initiated a project that was aimed at understanding the petroleum maturation and mineralization history of parts of the Brooks Range that were previously poorly characterized. The project, titled ?Regional Fluid Flow and Basin Modeling in Northern Alaska,? was undertaken in collaboration with industry, academia, and other government agencies. This Circular contains papers that describe the results of the recently completed project. The studies that are highlighted in these papers have led to a better understanding of the following: *The complex sedimentary facies relationships and depositional settings and the geochemistry of the sedimentary rocks that host the deposits (sections 2 and 3). *The factors responsible for formation of the barite and zinc deposits

  13. Tectonic evolution of Tethyan tectonic field, formation of Northern Margin basin and explorative perspective of natural gas in Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Analyzing the characteristics of the Tethyan tectonic field, the authors think that the Tethyan tectonic field underwent three evolutional stages: closing of Paleo-Tethys and rifting of Neo-Tethys from early Permian to late Triassic, subduction of Neo-Tethys and collision between the Indian plate and the Eurasia plate from Jurassic to early of low Tertiary, and collision between the Arab plate and the Eurasia plate and the A-type subduction of Indian plate from late of low Tertiary to the present. Combining the evolution of the Tethyan orogenic belt with the characteristics of the Northern Margin basin, it is suggested that the sedimentary and tectonic characteristics and types of the Northern Mar-gin basin are controlled by the formation and evolution of the Tethyan orogenic belt and the ingression of Tethys. The evolution of Northern Margin basin can be divided into three development stages: back-arc foreland basin from late Permian to Triassic, the back-arc fault subsidence and depression from Jurassic to the early of low Tertiary, and the reactive foreland basin from the late of low Tertiary to the present. The Northern Margin basin in the Tethyan tectonic field is an important region for natural gas accumulation, and the Tarim Basin is a part of this region.

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

    OpenAIRE

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

    2006-01-01

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

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

    Science.gov (United States)

    Armijo, Rolando; Thiele, Ricardo

    1990-04-01

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

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

    Science.gov (United States)

    Araya, Juan Francisco; Valdés, Ángel

    2016-01-01

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

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

    Science.gov (United States)

    Valdés, Ángel

    2016-01-01

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

  18. Linking basin evolution to plate tectonic processes in (northern) Africa

    OpenAIRE

    Gravråk, Mariann

    2011-01-01

    Several sedimentary basins in Africa are classified as intracratonic basins, but no conclusive formation mechanism has been identified for these basin types. Tectonic subsidence curves may help in unraveling formation mechanisms or identify tectonic forcing for these basins. This thesis presents and analyses basin subsidence curves for basins in the interior of Africa and near its passive margins. A backstripping program has been written to solve the backstripping equations needed to make the...

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

    Directory of Open Access Journals (Sweden)

    Miguel Avendaño

    2011-07-01

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

  20. Digital assessment of northern and central Appalachian basin coals

    Energy Technology Data Exchange (ETDEWEB)

    Ruppert, L.F.; Tewalt, S.J.; Braff, L.J.; Wallack, R.N. [US Geological Survey National Center, Reston, VA (US)

    1999-10-01

    The US Geological Survey (USGS) is currently conducting a coal resource assessment of the coalbeds and zones that are projected to provide the bulk of the nation's resources for the next few decades. The Pittsburgh and Upper Freeport coals are the first two beds in the northern and central Appalachian basin region to undergo fully digital coal assessments. The bed-specific assessments are being carried out in partnership with the state geologic surveys of West Virginia, Ohio, Pennsylvania and Maryland. Comprehensive stratigraphic and geochemical data-bases have been developed for both of the beds. The extent of the bed with mined areas, structure contour, isopach, and overburden thickness maps for the Pittsburgh coal bed have been realised as USGS open-file reports. The articles includes several detailed maps showing the export of the Pittsburgh coalbed, ash yield, sulphur contents and calorific value of the coal by county, structure contours, overburden thickness and isopac lines. 10 figs., 2 tabs.

  1. An integrated framework to assess adaptation options to climate change impacts in an irrigated basin in Central North Chile

    Science.gov (United States)

    Vicuna, S.; Melo, O.; Meza, F. J.; Alvarez, P.; Maureira, F.; Sanchez, A.; Tapia, A.; Cortes, M.; Dale, L. L.

    2013-12-01

    Future climate conditions could potentially affect water supply and demand on water basins throughout the world but especially on snowmelt-driven agriculture oriented basins that can be found throughout central Chile. Increasing temperature and reducing precipitation will affect both the magnitude and timing of water supply this part of the world. Different adaptation strategies could be implemented to reduce the impacts of such scenarios. Some could be incorporated as planned policies decided at the basin or Water Use Organization levels. Examples include changing large scale irrigation infrastructure (reservoirs and main channels) either physically or its operation. Complementing these strategies it is reasonable to think that at a disaggregated level, farmers would also react (adapt) to these new conditions using a mix of options to either modify their patterns of consumption (irrigation efficiency, crop mix, crop area reduction), increase their ability to access new sources of water (groundwater, water markets) or finally compensate their expected losses (insurance). We present a modeling framework developed to represent these issues using as a case study the Limarí basin located in Central Chile. This basin is a renowned example of how the development of reservoirs and irrigation infrastructure can reduce climate vulnerabilities allowing the economic development of a basin. Farmers in this basin tackle climate variability by adopting different strategies that depend first on the reservoir water volume allocation rule, on the type and size of investment they have at their farms and finally their potential access to water markets and other water supplies options. The framework developed can be used to study these strategies under current and future climate scenarios. The cornerstone of the framework is an hydrology and water resources model developed on the WEAP platform. This model is able to reproduce the large scale hydrologic features of the basin such as

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

    NARCIS (Netherlands)

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

    2011-01-01

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

  3. 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

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

    Science.gov (United States)

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

    2008-05-01

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

  5. Fluid flow in the northern Broad Fourteens Basin during Late Cretaceous inversion

    NARCIS (Netherlands)

    Oude Essink, Gualbert

    2003-01-01

    A basin-scale hydrogeological study of the inverted northern Broad Fourteens Basin, Netherlands offshore, has resulted in a reconstruction of geological evolution, an estimate of Late Cretaceous topography and model scenarios of syn-inversion meteoric water infiltration. This study was performed in

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

    Science.gov (United States)

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

    2015-04-01

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

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

    Science.gov (United States)

    Kampf, Stephanie K.; Tyler, Scott W.

    2006-02-01

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

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

    Science.gov (United States)

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

    2005-08-01

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

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

    Directory of Open Access Journals (Sweden)

    NANCY ORELLANA-HALKYER

    2010-12-01

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

  10. Deep crustal structure of the Adare and Northern Basins, Ross Sea, Antarctica, from sonobuoy data

    Science.gov (United States)

    Selvans, M. M.; Stock, J. M.; Clayton, R. W.; Cande, S.; Granot, R.

    2014-11-01

    Extension associated with ultraslow seafloor spreading within the Adare Basin, in oceanic crust just north of the continental shelf in the Ross Sea, Antarctica, extended south into the Northern Basin. Magnetic and gravity anomaly data suggest continuity of crustal structure across the continental shelf break that separates the Adare and Northern Basins. We use sonobuoy refraction data and multi-channel seismic (MCS) reflection data collected during research cruise NBP0701, including 71 new sonobuoy records, to provide constraints on crustal structure in the Adare and Northern Basins. Adjacent 1D sonobuoy profiles along several MCS lines reveal deep crustal structure in the vicinity of the continental shelf break, and agree with additional sonobuoy data that document fast crustal velocities (6000-8000 m/s) at shallow depths (1-6 km below sea level) from the Adare Basin to the continental shelf, a structure consistent with that of other ultraslow-spread crust. Our determination of crustal structure in the Northern Basin only extends through sedimentary rock to the basement rock, and so cannot help to distinguish between different hypotheses for formation of the basin.

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

    Science.gov (United States)

    Souvignet, M.; Heinrich, J.

    2010-03-01

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

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

    Science.gov (United States)

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

    2010-12-01

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

  13. Paleogene palaeogeography and basin evolution of the Western Carpathians, Northern Pannonian domain and adjoining areas

    Science.gov (United States)

    Kováč, Michal; Plašienka, Dušan; Soták, Ján; Vojtko, Rastislav; Oszczypko, Nestor; Less, György; Ćosović, Vlasta; Fügenschuh, Bernhard; Králiková, Silvia

    2016-05-01

    The data about the Paleogene basin evolution, palaeogeography, and geodynamics of the Western Carpathian and Northern Pannonian domains are summarized, re-evaluated, supplemented, and newly interpreted. The presented concept is illustrated by a series of palinspastic and palaeotopographic maps. The Paleogene development of external Carpathian zones reflects gradual subduction of several oceanic realms (Vahic, Iňačovce-Kričevo, Szolnok, Magura, and Silesian-Krosno) and growth of the orogenic accretionary wedge (Pieniny Klippen Belt, Iňačovce-Kričevo Unit, Szolnok Belt, and Outer Carpathian Flysch Belt). Evolution of the Central Western Carpathians is characterized by the Paleocene-Early Eocene opening of several wedge-top basins at the accretionary wedge tip, controlled by changing compressional, strike-slip, and extensional tectonic regimes. During the Lutetian, the diverging translations of the northward moving Eastern Alpine and north-east to eastward shifted Western Carpathian segment generated crustal stretching at the Alpine-Carpathian junction with foundation of relatively deep basins. These basins enabled a marine connection between the Magura oceanic realm and the Northern Pannonian domain, and later also with the Dinaridic foredeep. Afterwards, the Late Eocene compression brought about uplift and exhumation of the basement complexes at the Alpine-Carpathian junction. Simultaneously, the eastern margin of the stretched Central Western Carpathians underwent disintegration, followed by opening of a fore-arc basin - the Central Carpathian Paleogene Basin. In the Northern Hungarian Paleogene retro-arc basin, turbidites covered a carbonate platform in the same time. During the Early Oligocene, the rock uplift of the Alpine-Carpathian junction area continued and the Mesozoic sequences of the Danube Basin basement were removed, along with a large part of the Eocene Hungarian Paleogene Basin fill, while the retro-arc basin depocentres migrated toward the east

  14. Meso-Cenozoic basin evolution in northern Korean Peninsula

    Institute of Scientific and Technical Information of China (English)

    PAK Hyon Uk; LYANG To Jun; LIU Yongjiang; HYON Yun Su; KIM Gyong Chol

    2009-01-01

    In the Korean Peninsula the Meso-Cenozoic basins were mainly formed due to fault block and block movement. The Mesozoic fracture structures correspond basically to modern large rivers in direction. Such faults were usually developed to rift and formed lake-type tectonic basin, such as the Amrokgang-, Taedonggang-, Ryesonggang-, Hochongang-, Jangphari-, Susongchon-, Pujon-, and Nampho basins. The Mesozoic strata are considered to be divided into the Lower Jurassic Taedong System, Upper Jurassic Jasong System, Upper Jurassic- -early Lower Cretaceous Taebo System, and the Upper Cretaceous- -Paleocene (Chonjaebong, Hongwon, Jaedok Series). The Cenozoic block movement succeeded the Mesozoic fault block movement. The Kilju-Myongchon Graben and Tumangang Basin, etc, are the basins related to the fault zones developed from the Oligocene to Miocene. In addition, the Tertiary basins were formed in many areas in the Miocene (e.g. Sinhung, Oro, Hamhung, Yonghung, Anbyon, Cholwon, etc). The Cenozoic sedimentation occurred mainly from the late Oligocene to Miocene. The Kilju-Myongchon Graben was the fore deep connected to the sea and the basins inclined in the Chugaryong Fault Zone are intramountain basins. Therefore, coal-bearing beds and clastic rocks in the intramountain basins and rare marine strata and terrigenous clastic rocks are main sedimentary sequences in the Cenozoic.

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

    OpenAIRE

    Paola Bolados García; Guillaume Boccara

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Paola Bolados García

    2015-06-01

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    HECTOR A VARGAS

    2004-06-01

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

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

    Science.gov (United States)

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

    2014-06-01

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

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

    Science.gov (United States)

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

    2014-02-01

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

  1. Evidence of a giant helmeted frog (Australobatrachia, Calyptocephalellidae) from Eocene levels of the Magallanes Basin, southernmost Chile

    Science.gov (United States)

    Otero, Rodrigo A.; Jimenez-Huidobro, Paulina; Soto-Acuña, Sergio; Yury-Yáñez, Roberto E.

    2014-11-01

    The fossil record of frogs from South America has improved dramatically in recent years. Here we describe a distal fragment of a large-sized humerus recovered from the middle-to-upper Eocene of southernmost Chile. The large distally located ventral condyle, and the presence of two epicondyles (radial and ulnar) confirm its identity as an anuran humerus. Comparisons with humeri from extant and fossil South American neobatrachians suggest a phylogentic affinity to calyptocephalellids (Australobatrachia). If correct, the new fossil represents the first occurrence of this family in high latitudes of South America and the first amphibian recovered from the Magallanes (=Austral) Basin. The humerus also represents evidence for one of the largest frogs known to date from anywhere in the world. Such exceptional body size may reflect an unusually hot and damp palaeoenvironment.

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

    OpenAIRE

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

    2012-01-01

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

  3. Analysis of the dynamic of underground water in Agua Verde, Quebrada de Taltal, region of Antofagasta, Chile

    International Nuclear Information System (INIS)

    The extreme aridity and geological situation in northern. Chile requires an exhaustive investigation on water resources for supporting rational usage. The Direccion General de Aguas and Comision Chilena de Energia Nuclear have performed studies in arid zones in northern Chile using isotopic and hydrochemical tools. In Quebrada de Taltal's basin, located in one of the must arid arid zones of Chile (Segunda Region de Antofagasta), was studies groundwater dynamics and recharge process from a geochemical approach in terms of water quality, temperature and isotopic composition (2H, 18O, 3H, 14C). The recharge generated above 3000 m a.s.t has a slow dynamics and involve little flow (author)

  4. Multiple Refuge Bat Inventory: Great Basin & Great Northern LCC

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This was a cooperative project between the Upper Columbia Basin Network (UCBN) of the National Park Service I&M Program, USFWS Region 1 I&M Program (R1...

  5. Petroleum potential of the northern Sinu-San Jacinto Basin, Colombia: an integrated petroleum system and basin modeling approach

    Energy Technology Data Exchange (ETDEWEB)

    Nino, Christian H.; Goncalves, Felix T.T.; Bedregal, Ricardo P. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Lab. de Modelagem de Bacias (LAB2M); Azevedo, Debora A. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica; Landau, Luis [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Lab. de Metodos Computacionais em Engenharia (LAMCE)

    2004-07-01

    The northern Sinu-San Jacinto basin, located in the northwestern corner of South America (Colombia), belongs to the accretionary prism that resulted from the collision and subduction of the Caribbean plate under the South America plate. Despite all the previous exploratory efforts, solely a few small sub-commercial oil and gas accumulation have been found up to now. The geological and geochemical information acquired by different companies during the lasts decades was integrated with new geochemical analysis and basin modeling to characterize the petroleum systems, to reconstruct the hydrocarbon charge history in the study area and to better assess the exploratory risk. (author)

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

    OpenAIRE

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

    2012-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Héctor A. Vargas

    2009-06-01

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

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

    Science.gov (United States)

    Sanhueza, Pedro

    2015-08-01

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

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

    Science.gov (United States)

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

    2009-12-01

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

  10. Shear-wave velocity model of the basin of Santiago de Chile derived from ambient noise measurements for the determination of seismic site conditions and amplification

    Science.gov (United States)

    Pilz, M.; Parolai, S.; Picozzi, M.; Wang, R.; Leyton, F.; Campos, J. A.; Zschau, J.

    2009-12-01

    Generally, the most intense shaking during an earthquake occurs near the rupture fault and decreases with distance away from the fault. However, in a single earthquake the shaking at one site can easily be several times stronger than at another site, even when their distance from the rupture fault is the same. Such site effects are mainly caused by the softness of the soil near the surface and by the thickness of the sediments above hard rock. Seismic site characterization therefore requires usually substantial investment both in time and money for geophysical data acquisition. On the other hand, the necessity of estimating seismic risk for large urban areas like Santiago de Chile wants for at least a first order classification of soil and building vulnerability and therefore needs the definition of proxies. Recently, Wald and Allen (2007) suggested that the slope of topography might serve as a suitable parameter for the estimation of site effects irrespective of the spatial resolution used. Measurements of seismic noise at 146 sites have been carried out in the northern part of Santiago de Chile to determine the fundamental resonance frequency of the sites. The spatial variation in the thickness of the sedimentary cover, known from previous gravimetric investigations, varies significantly over short scale and is roughly retrieved from the peak in the horizontal-to-vertical (H/V) ratios of ambient noise. We inverted the H/V spectra individually for receiving local S-wave velocity profiles. For the inversion procedure, we also used additional geological and geophysical information. The resulting 3D model was derived for a 26 km X 12 km area by interpolation between the single S-wave velocity profiles with a kriging technique and shows good agreement with the few existing velocity profiles but also allows to image the entire area as well as deeper parts of the basin in more detail. Significant variations in the S-wave velocity-depth gradient are found. The wealth of

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

    Directory of Open Access Journals (Sweden)

    J. A. Díaz-Ochoa

    2011-01-01

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

  12. Low palaeoelevation of the northern Lhasa terrane during late Eocene: Fossil foraminifera and stable isotope evidence from the Gerze Basin

    OpenAIRE

    Yi Wei; Kexin Zhang; Garzione, Carmala N.; Yadong Xu; Bowen Song; Junliang Ji

    2016-01-01

    The Lhasa terrane is a key region for understanding the paleoelevation of the southern Tibetan Plateau after India-Asia collision. The Gerze Basin, located in the northern part of the Lhasa terrane, is a shortening-related basin. We discovered Lagena laevis (Bandy) fossils in upper Eocene strata of the Gerze Basin. This type of foraminifera is associated with lagoon and estuarine environments, indicating that the northern part of the Lhasa terrane was near sea level during the late Eocene. We...

  13. Discussion on the characteristics of Meso-Cenozoic U-productive basins in northern China and their prospecting direction

    International Nuclear Information System (INIS)

    Based on the study of sedimentary evolution characteristics of main sedimentary basins and combined with characteristics of known uranium-productive basins in northern China, and the analysis on airborne geophysical survey data, the principles for selecting prospecting and target area have been set up. And the prospecting direction for uranium in Meso-Cenozoic basins of northern China has been proposed through a preliminary analysis. (authors)

  14. Potential Inundation Hazards in the Taipei Basin Induced by Reactivation of the Shanchiao Fault in Northern Taiwan

    OpenAIRE

    Jihn-Sung Lai; Chun-Ying Chiu; Hsiang-Kuan Chang; Jyr-Ching Hu; and Yih-Chi Tan

    2010-01-01

    The Shanchiao fault, located to the west of the Taipei Basin in northern Taiwan, is a highly active normal fault that has a left-slip component and fault length of over 40 km. We suggest that the Shanchiao fault still has the ability to induce coseismic subsidence in the Taipei Basin under present extensional regime of northern Taiwan. In order to characterize the coseismic ground deformation and assess the potential inundation hazards in Taipei Basin, we estimate surface displacements using ...

  15. The U.S. Geological Survey`s National Coal Resource Assessment: The Northern and Central Appalachian Basin

    Energy Technology Data Exchange (ETDEWEB)

    Ruppert, L.; Bragg, L.; Tewalt, S. [Geological Survey, Reston, VA (United States)

    1996-09-01

    The US Geological Survey (USGS) Energy Resource Surveys Program is currently conducting a five-year National Coal Resource Assessment project. Primary focus is on the quality and quantity of top-producing coal beds and coal zones in five of the nine major coal producing regions in the US. These regions include the (1) Northern and Central Appalachian Basin, (2) Gulf Coastal Plain, (3) Illinois Basin, (4) Colorado Plateau, and (5) Powder River Basin and Northern Great Plains.

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

    Science.gov (United States)

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

    2012-05-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2003-08-01

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

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

    Science.gov (United States)

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

    2012-06-01

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

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

    Science.gov (United States)

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

    2015-11-01

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

  1. Use of environmental isotopes to evaluate natural and antropic sources of groundwater in an area with multiple land uses, Santiago Norte Basin, Chile

    International Nuclear Information System (INIS)

    One of the key aspects, that has significant implications in groundwater resources management in urban areas, is the identification of the potential multiple sources of aquifer recharge. This paper will discuss data from an ongoing project aiming to develop a management strategy for groundwater development in the northern part of the Santiago Basin, Chile. The study area is densely populated with multiples land practices including urban (60%), agriculture and recreational (30%), and industrial (10%) uses. The aquifers are composed of sedimentary granular units related, genetically, to the evolution of the alluvial fan of Mapocho River. Unconfined aquifers are developed in the proximal alluvial fan facies, while confined and semi-confined aquifers are associated to distal alluvial fan deposits. Naturally these aquifers must be recharged by infiltration from small local watershed associated to basement outcrops and, in a more regional scale, from lateral recharge of upgradient aquifers, recharged in the upper part of the Mapocho River watershed. Potential antropic sources of recharge could be associated, with leakage from the old water supply network and sewage system in the urban area, and/or irrigation channels that exist within and in the margin of the basin. All these water networks are principally supplied with water from the Maipo River, located to the south of the study basin. An extensive hydrogeological and geochemical study is being carried out in the study area to evaluate the groundwater flow system and the different sources of aquifer recharge. The evaluation of water sources is primarily being carried out using oxygen-18, deuterium and tritium. Sulfate-34 and oxygen-18 in sulfate are also being used to evaluate sources of groundwater sulfate, that could also provide additional information about water sources. The results of more than 100 groundwater samples and more than 20 surface water samples are summarized on Figure 1b. The broad range of isotope

  2. Tectonoestratigraphic and Thermal Models of the Tiburon and Wagner Basins, northern Gulf of California Rift System

    Science.gov (United States)

    Contreras, J.; Ramirez Zerpa, N. A.; Negrete-Aranda, R.

    2014-12-01

    The northern Gulf of California Rift System consist sofa series faults that accommodate both normal and strike-slip motion. The faults formed a series of half-greens filled with more than 7 km of siliciclastic suc­cessions. Here, we present tectonostratigraphic and heat flow models for the Tiburón basin, in the southern part of the system, and the Wag­ner basin in the north. The models are constrained by two-dimensional seis­mic lines and by two deep boreholes drilled by PEMEX­-PEP. Analysis of the seismic lines and models' results show that: (i) subsidence of the basins is controlled by high-angle normal faults and by flow of the lower crust, (ii) basins share a common history, and (iii) there are significant differences in the way brittle strain was partitioned in the basins, a feature frequently observed in rift basins. On one hand, the bounding faults of the Tiburón basin have a nested geometry and became active following a west-to-east sequence of activation. The Tiburon half-graben was formed by two pulses of fault activity. One took place during the protogulf extensional phase in the Miocene and the other during the opening of Gulf of California in the Pleistocene. On the other hand, the Wagner basin is the result of two fault generations. During the late-to middle Miocene, the west-dipping Cerro Prieto and San Felipe faults formed a domino array. Then, during the Pleistocene the Consag and Wagner faults dissected the hanging-wall of the Cerro Prieto fault forming the modern Wagner basin. Thermal modeling of the deep borehole temperatures suggests that the heat flow in these basins in the order of 110 mW/m2 which is in agreement with superficial heat flow measurements in the northern Gulf of California Rift System.

  3. Adaptation tot changing water resources in the Ganges basin, northern India

    NARCIS (Netherlands)

    Moors, E.J.; Groot, A.M.E.; Biemans, H.; Terwisscha van Scheltinga, C.T.H.M.; Siderius, C.; Stoffel, M.

    2011-01-01

    An ensemble of regional climate model (RCM) runs from the EU HighNoon project are used to project future air temperatures and precipitation on a 25 km grid for the Ganges basin in northern India, with a view to assessing impact of climate change on water resources and determining what multi-sector a

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

    Science.gov (United States)

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

    2010-05-01

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

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

    Science.gov (United States)

    Cortés; Miranda; Rosenmann; Rau

    2000-12-01

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

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

    Science.gov (United States)

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

    2016-06-01

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

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

    Science.gov (United States)

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

    2010-05-01

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

  8. The mechanics of continental extension in Qiongdongnan Basin, northern South China Sea

    Science.gov (United States)

    Zhao, Zhongxian; Sun, Zhen; Wang, Zhenfeng; Sun, Zhipeng

    2015-09-01

    Located in the intersection of NE-trended rifted margin of South China Sea (SCS) and NW-oriented Ailao Shan-Red River Shear Zone (RRSZ), Qiongdongnan Basin shows significant differences in geological features from west to east, indicating different mechanics of continental extension. Based on the dense and updated multichannel seismic profiles, we disclose the characteristics of the remnant crystalline crust. Besides, we analyze the basin structures, calculate the stretching factors of upper and whole crust, and compute the syn-rift and post-rift unloaded tectonic subsidence along three selected transects in the west, middle and east of Qiongdongnan Basin. The crust thickness is 22 km on the northern and southern parts of Qiongdongnan Basin and thins gradually towards the central depression with two extremely thinned domains (factors of crust are 1.5-2 on both sides and increase remarkably towards the central depression (β > 2) with two extremely stretched domains (β > 9), of which one is in Ledong Sag in the west and another is in Baodao and Changchang Sags in the east. However, the mechanics of continental extension vary significantly from west to east. The simple shear dominates in the west, the pure shear dominates in the east, and it is intermediate between the two end members of simple shear and pure shear in the middle of Qiongdongnan Basin. The simple shear in the west of Qiongdongnan Basin is probably controlled by the left-lateral movement of RRSZ. The pure shear in the east is probably related to the Cenozoic rifting along the northern continental margin of SCS. The transitional zone in the middle of Qiongdongnan Basin is possibly the combined results of the left-lateral movement of RRSZ and the Cenozoic rifting along the northern continental margin of SCS.

  9. A decision support tool for basin irrigation in northern Nigeria

    Directory of Open Access Journals (Sweden)

    Olumuyiwa S. Asaolu

    2009-07-01

    Full Text Available Inadequate rainfall, water resources scarcity and attendant food security-related problems have made irrigation technology a necessity. This work presents the development of a decision support system for solving surface irrigation design problems in northern Nigeria. The arid northern states affected by desert encroachment constitute a good candidate and their climatological data was obtained from the Nigerian Metrological Agency. The interactive system was defined in terms of inputs and outputs. The inputs were properties of soil, surface irrigation method and climate. The outputs were mainly the quantity of water application, scheduling pattern, possible design configuration, advance time, cut-off time, application rate, and water use efficiency. The FAO Penman-Monteith equation was used to estimate evapotranspiration values of major crops grown in Nigeria. Mathematical models outlined by Walker and Skogerboe were adapted, and heuristics applied in determining the best configuration that achieves optimum water application efficiency. We encoded the knowledge base using Matlab® software. The application was successfully used for the modification of a farm irrigation scheme in Kaduna state. This indicates that the adoption of new technologies for irrigation design issues could enhance agricultural productivity in northern Nigeria.

  10. Infrastructure development and agricultural exposure to climate variability and change: lessons from the Limarí basin in Central Chile

    Science.gov (United States)

    Vicuna, S.; Alvarez, P.; Melo, O.; Dale, L. L.; Meza, F. J.

    2012-12-01

    The Limarí basin, located in Central Chile, is a world famous example of how the development of reservoirs and irrigation infrastructure can reduce climate vulnerabilities allowing the economic development of a basin. Before the infrastructure was developed low value crops such as cereals dominated land use acreage. Today high value crops such as vineyards, orchards and vegetables account for almost 50% of total land and cereals have almost disappear. Key to this evolution have been the reduction in water supply variability, access to international markets, increased irrigation efficiency, and the existence of water markets and other flexible and strong institutions that have helped moving the water from low to high value uses. These factors are related to each other sharing infrastructure development as a common root. The system of reservoirs in the Limarí basin was designed and has been operated since its construction with the premise that droughts in this basin do not last longer than 4 years. Until recently that had been the case and farmers have been able to withstand the impacts of droughts. When faced with water supply reductions farmers would select from a set of options to accommodate their needs including: water market participation, groundwater extraction and crop irrigation and crop acreage decisions. The use of these options has even allowed increasing total irrigated land mostly through the expansion of permanent water demand crops. In the past 9 years however, the basin has experienced a longer than usual drought, interrupting the reservoir refilling cycle that characterized climate variability in the region. This situation has led to dramatically low reservoir levels and continuous reductions in water supply. In addition, due to the already high levels of irrigation efficiency and large amount of acreage devoted to permanent water demand crops, the effectiveness of the portfolio of options available to farmers to accommodate to these stressing

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

    Science.gov (United States)

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

    2014-12-01

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2003-12-01

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

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

    Science.gov (United States)

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

    2007-01-01

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

  15. Evidence for bloc rotation tectonics in the seismic Cheliff basin (northern Algeria) from paleomagnetic investigations

    Science.gov (United States)

    El-M. Derder, Mohamed; Henry, Bernard; Amenna, Mohamed; Bayou, Boualem; Maouche, Said; Besse, Jean; Ayache, Mohamed; Abtout, Abdeslam

    2010-05-01

    The seismic activity in the Western Mediterranean area is mainly concentrated in northern Africa, particularly in northern Algeria, as it was shown by the 21 May 2003 Boumerdes and the 10 October 1980 El Asnam earthquakes (of moment magnitudes Mw =6.9, and Ms= 7.3 respectively), which were among the strongest recent ones recorded in the western Mediterranean area. This seismicity is due to the convergence between Africa and Eurasia plates since at least the Oligocene. This convergence involves a transpression tectonic with N-S to NNW-SSE direction of shortening, which is expressed by active deformations along the boundary of these two plates. In Algeria, the seismicity is focused in a coastal zone (the Tell Atlas) in the northern part of the country. Active structures define there NE-SW trending folds and NE-SW sinistral transpressive faults, which affect the intermountain and coastal basins of Neogene to Quaternary age (e.g. " Cheliff "basin, " Mitidja "basin). These reverse faults are coupled with NW-SE to E-W trending strike-slip deep faults. The active deformation in northern Algeria could thus be explained by a kinematic model of bloc rotation: the transpression tectonics with NNW-SSE direction of convergence defines NE-SW oriented blocs, which have been possibly subjected to clockwise rotation. The aim of this study is to look for such blocks rotation in the "Cheliff" basin (northern Algeria), by using the paleomagnetic tool. A paleomagnetic study has been thus conducted on the midlle Miocene, Tortonian, Messinian and Pliocene sedimentary rocks cropping out on the eastern part of this basin. The study is still in progress, but despite the very weak intensity of the Natural Remanent Magnetization (NRM) measured on the samples, and the frequently observed magnetization instability during the thermal demagnetization, the preliminary results show that clockwise rotations have affected different sites of the studied area. The magnitude of these rotations varies

  16. Science-society collaboration for robust adaptation planning in water management - The Maipo River Basin in Chile

    Science.gov (United States)

    Ocampo Melgar, Anahí; Vicuña, Sebastián; Gironás, Jorge

    2015-04-01

    The Metropolitan Region (M.R.) in Chile is populated by over 6 million people and supplied by the Maipo River and its large number of irrigation channels. Potential environmental alterations caused by global change will extremely affect managers and users of water resources in this semi-arid basin. These hydro-climatological impacts combined with demographic and economic changes will be particularly complex in the city of Santiago, due to the diverse, counterpoised and equally important existing activities and demands. These challenges and complexities request the implementation of flexible plans and actions to adapt policies, institutions, infrastructure and behaviors to a new future with climate change. Due to the inherent uncertainties in the future, a recent research project entitled MAPA (Maipo Adaptation Plan for its initials in Spanish) has formed a collaborative science-society platform to generate insights into the vulnerabilities, challenges and possible mitigation measures that would be necessary to deal with the potential changes in the M.R. This large stakeholder platform conformed by around 30 public, private and civil society organizations, both at the local and regional level and guided by a Robust Decision Making Framework (RDMF) has identified vulnerabilities, future scenarios, performance indicators and mitigation measures for the Maipo River basin. The RDMF used in this project is the XLRM framework (Lempert et al. 2006) that incorporates policy levers (L), exogenous uncertainties (X), measures of performance standards (M) and relationships (R) in an interlinked process. Both stakeholders' expertise and computational capabilities have been used to create hydrological models for the urban, rural and highland sectors supported also by the Water Evaluation and Planning system software (WEAP). The identification of uncertainties and land use transition trends was used to develop future development scenarios to explore possible water management

  17. Structure and seismic stratigraphy of deep Tertiary basins in the northern Aegean Sea

    Science.gov (United States)

    Beniest, Anouk; Brun, Jean-Pierre; Smit, Jeroen; Deschamps, Rémy; Hamon, Youri; Crombez, Vincent; Gorini, Christian

    2015-04-01

    Whereas active basin formation in the Aegean Sea is illustrated by seafloor bathymetry, the sedimentary and tectonic history of Tertiary basins is poorly known as existing offshore industrial seismic and well-log data are not easily accessible. We studied the evolution of the northern Aegean Sea with a focus on the North Aegean Trough and the Northern Skyros Basin, which are amongst the deepest basins of the northern Aegean domain. Structural and seismic stratigraphic interpretation of a 2D seismic dataset retrieved in the 1970's is combined with the well-investigated records of the onshore deep basins of northern Greece and Western Turkey. A general seismic signature chart was established using onshore basin stratigraphy and poorly-constrained well data. The studied domain shows two sharp unconformities that correspond to the Eocene-Oligocene transition and the Miocene-Pliocene shift, respectively. These transitions were then used as pillars for a more detailed structural and seismic stratigraphic interpretation. A NW-SE trending seismic line that cross-cuts the southern part of the NE-SW-trending North Aegean Through displays the main features that are observed in the area: 1) an overall basin geometry that is rather symmetrical; 2) pre-Pliocene units affected by steep normal faults; 3) a rather constant thickness of Oligocene sediments that define a depocenter with an apparent NW-SE orientation; 4) an ablation of Miocene sediments by erosion, likely related to the Messinian Salinity Crises (MSC); (5) thick deltaic/turbiditic deposits in the NE-SW oriented central through of Neogene age; 6) trans-tensional growth patterns in Pliocene and Quaternary sediments that combine NE-SW steeply dipping fault zones, more likely corresponding to strike-slip corridors, and E-W-trending normal faults. The evidence listed above suggest that, in the northern Aegean Sea, (1) extension started at the latest during the Late Eocene/Early Oligocene (data quality does not allow for a

  18. Estimating flows in ungauged river basins in northern Mozambique

    Science.gov (United States)

    Minihane, M.

    2011-12-01

    In many regions across the globe, there are limited streamflow observations and therefore limited knowledge of availability of surface water resources. In many cases, these rivers lie in countries that would benefit from economic development and improved access to water and sanitation services, both of which are linked to water resources. Additional information about streamflow in these watersheds is critical to water resources planning and economic development strategies. In southeastern Africa, the remote Rovuma River lies on the border between Mozambique and Tanzania. There are limited historic measurements in the main tributary and no recent observations. Improved knowledge of the water resource availability and inter-annual variability of the Rovuma River will enhance transboundary river basin management discussions for this river basin. While major rivers farther south in the country are more closely monitored, those in the north have gauging stations with only scattered observations and have not been active since the early 1980's. Reliable estimates of historic conditions are fundamental to water resources planning. This work aims to provide estimates in these rivers and to quantify uncertainty and bounds on those estimates. A combination of methods is used to estimate historic flows: simple index gauge methods such as the drainage area ratio method and mean flow ratio method, a statistical regression method, a combination of an index gauge method and global gridded runoff data, and a hydrological model. These results are compared to in-situ streamflow estimates based on stage measurements and rating curves for the basins and time frames for which data is available. The evaluation of the methods is based on an efficiency ratio, bias, and representation of seasonality and inter-annual variability. Use of gridded global datasets, either with the mean flow ratio method or a hydrological model, appears to provide improved estimates over use of local observations

  19. Hydrogeochemical exploration for uranium within the Athabasca Basin, northern Saskatchewan

    International Nuclear Information System (INIS)

    As part of exploration programs for unconformity-related uranium deposits, the chemistry of deep ground waters has been studied from throughout the Athabasca Basin. Samples have been collected from routine, small-diameter, exploration diamond drillholes, and considerable emphasis has been placed on ensuring that they represent true ground waters. The authors have measured both major and minor constituents, including various uranium daughter products. Ground-water samples collected from the vicinity of uranium mineralization have consistently high levels of uranium, radium, radon and helium. Although they have not been able to establish the maximum extent of the hydrogeochemical anomalies in this environment, they have detected anomalies at distances of up to tens of meters from known mineralization. (orig.)

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Science.gov (United States)

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

    2006-10-01

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

  2. Sustainable Transformations of Water Supply Regimes. The Cuvelai-Etosha Basin in Central Northern Namibia.

    OpenAIRE

    Zimmermann, Martin

    2013-01-01

    In this thesis, an interdisciplinary modelling approach for water resources management and its application is presented that is able to deal with socio-technical systems that are characterised by a multiplicity of variables, interdependencies, and actors. The case study area is the Cuvelai-Etosha Basin, which is located in central northern Namibia. Approximately 850,000 people or 40 % of the Namibian population live in this area, which comprises only about 14 % of the country’s area. The regi...

  3. Competition, Cooperation, and the Emergence of Regional Centers in the Northern Lake Titicaca Basin, Peru

    OpenAIRE

    Levine, Abigail Ruth

    2012-01-01

    Regional centers with dense populations developed in the Titicaca Basin during the late Middle (ca. 1300-500 BC) and early Upper Formative (ca. 500 BC- AD 400) Periods. These aggregated settlements have long been considered the hallmark of intermediate societies. This dissertation focuses on the transition from small village societies to ones with pronounced social, political, and economic hierarchies. In the northern Titicaca region, only two sites--Taraco and Pukara--became powerful cent...

  4. Analysis on Structural Control of Coal Distribution in the Northern Qaidam Basin, NW China

    Institute of Scientific and Technical Information of China (English)

    LIU Tianji; WANG Tong; ZHAN Wenfeng

    2008-01-01

    The distribution of the Jurassic coal measures in the northern Qaidam Basin is obviously controlled by the regional structures. Based on the existing data of coalfield exploration and combined with the analysis of coalfield basement structures, features of the main faults, and the distribution of coal measures, this paper brings forward a scheme of coalfield tectonic divisional units and the definition of the coal-controlling structural styles in the northern Qaidam Basin. The structure control of the distribution of coal measures is further discussed. Several stages of regional tectonic activities since the Indosinian has led to the distribution of coal measures into the characteristics of zonation from the north to south and block from east to west. The results indicate that the structural deformations are the most intense in the front of the three uplifted belts, which are characterized by the combination of thrusts. The coal measures are uplifted to the shallow formations, and are easy to be exploited, but the scale of mines is small because of serious damages by the coal distribution. On the contrary, the stress and strain are weak in the three depressions, with the coal-controlling structural styles being mainly the thrust-fold and thrust-monocline combinations. The distribution of coals in the depressions is relatively stable. The shallower part of the depression will become the key areas for exploration and development of coal resources in the northern Qaidam Basin.

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

    OpenAIRE

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

    2003-01-01

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

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

    OpenAIRE

    Miguel Avendaño; Marcela Cantillánez

    2011-01-01

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

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

    OpenAIRE

    Gabriela Böhm; Eleuterio Yáñez; Fernando Espíndola

    2005-01-01

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

  8. Epidemiología de la difilobotriasis en la cuenca del río Valdivia, Chile Epidemiologia de difílobotriase na bacia do rio Valdivia, Chile Epidemiology of diphyllobothriasis in the Valdivia River basin, Chile

    Directory of Open Access Journals (Sweden)

    Patricio Torres

    1989-02-01

    por Diphyllobothrium latum nas áreas afetadas foi produzida pela ingestão de peixes defumados ou cozidos insuficientemente. A pesquisa realizada em l .450 peixes pertencentes a 4 espécies introduzidas e 11 autóctones capturadas na bacia do rio Valdivia mostrou a existência de plerocercoides de Diphyllobothrium latum e/ou D. dendriticum nas espécies introduzidas Salmo gairdneri e S. trutta além de outras autoctones. A prevalência ou intensidade média das infecções nos peixes bem como o grau de agregação das subpopulações variaram nos diferentes locais estudados. Na bacia do río Valdivia, alguns peixes atuaram como hospedeiros intermediários e outros como paratênicos das espécies de Diphyllobothrium encontradas. Como medidas de controle nos pontos de difilobotriase nas áreas estudadas sugere-se a melhoria das condições de saneamento básico, educação sanitária e tratamento das pessoas infectadas.In the Valdivia (Chile river basin 1,295 inhabitants of 6 riverside districts were examined between March and October 1987 and showed a 1.2% of prevalence by Diphyllobothrium in the districts of Riñihue and Las Huellas. Prevalence of 5.3% and 9.8% respectively were registered in dogs of the districts of Riñihue and Malihue. No cat or pig infection was observed in the different districts. The parasites recovered after the treatment were identified as Diphyllobothrium latum. Human infection by D. latum in the districts affected results from the consumption of smoked or insufficiently cooked fish. The investigation of 1,450 fish (4 exotic species and 11 autochthonous ones, caught in the Valdivia river basin in 1986 and 1987, showed the existence of plerocercoids of D. latum and/or Diphyllobothrium dendriticum in Salmo gairdneri and Salmo trutta among exotic fish and in some autochthonous species. Prevalence and mean intensity in the infection of fish as well as the degree of aggregation in the infrapopulations varied in the different districts. Some

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

    Science.gov (United States)

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

    2016-04-01

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

  10. Tectonic control on the Late Quaternary hydrography of the Upper Tiber Basin (Northern Apennines, Italy)

    Science.gov (United States)

    Benvenuti, Marco; Bonini, Marco; Moroni, Adriana

    2016-09-01

    We examine the intramontane Upper Tiber Basin in the Northern Apennines (central Italy), where sub-orthogonal fault systems forced river deviation and the abandonment of alluvial fans since the late Middle Pleistocene. Archaeological material, spanning the Middle Palaeolithic-Iron Age, was collected mostly from the surface of the Late Quaternary alluvial landforms and related deposits (MUP and HOL units). This information contributed to the partial dating of seven major stages of drainage development. Normal faults parallel and transverse to the basin trend were active at different times and conditioned the valley pattern of the Middle (MUP1-2)-Late (MUP3) Pleistocene Tiber, Singerna, Sovara and Tignana rivers, which still flow today into the basin. The MUP1 and the MUP3 fans were beheaded by the displacement of their feeder valleys along the basin-transverse Carmine and Montedoglio faults. In some cases, the former feeder rivers underwent stream piracy but their courses mostly deviated in response of the topographic gradient created by faulting, as well as through the incision of new valleys that exploited the lithological contrast along the fault lines. The MUP3 Tignana fan was abandoned mostly due to the activity of the basin-parallel, dip-slip Sansepolcro fault. Subsidence driven by the basin-parallel Anghiari and Sansepolcro fault systems also provided the accommodation space for the MUP3 and HOl1-2 Afra fans between Late Pleistocene and early-mid Holocene. This study exemplifies the interplay between longitudinal and transverse fault systems, and the Late Quaternary hydrographic evolution of an extensional basin settled in the axial zone of an active fold-and-thrust belt. Although the faulting has interacted with the forcing exerted by the Late Quaternary climate fluctuations on the basin drainage systems, the tectonic rates are sufficiently high to represent the prime controller on base-level change and drainage routing patterns.

  11. Reactive Transport of Nitrate in Northern California Groundwater basins: An Integrated Characterization and Modeling Approach

    Science.gov (United States)

    Esser, B. K.; Moran, J. E.; Hudson, G. B.; Carle, S. F.; McNab, W.; Tompson, A. F.; Moore, K.; Beller, H.; Kane, S.; Eaton, G.

    2003-12-01

    More than 1/3 of active public drinking water supply wells in California produce water with nitrate-N levels indicative of anthropogenic inputs (> 4 mg/L). Understanding how the distribution of nitrate in California groundwater basins will evolve is vital to water supply and infrastructure planning. To address this need, we are studying the basin-scale reactive transport of nitrate in the Livermore and Llagas basins of Northern California. Both basins have increasingly urban populations heavily reliant on groundwater. A distinct nitrate "plume" exists in the Livermore Basin (Alameda County) whereas pervasive nitrate contamination exists in shallow groundwaters of the Llagas Basin (Santa Clara County). The sources and timing of nitrate contamination in these basins are not definitively known; septic systems, irrigated agriculture and livestock operations exist or have existed in both areas. The role of denitrification in controlling nitrate distribution is also unknown; dissolved oxygen levels are sufficiently low in portions of each basin as to indicate the potential for denitrification. We have collected water from 60 wells, and are determining both groundwater age (by the 3H/3He method) and the extent of denitrification (by the excess N2 method). Excess nitrogen is being determined by both membrane-inlet and noble gas mass spectrometry, using Ar and Ne content to account for atmospheric N2. We are also analyzing for stable istotopes of nitrate and water, nitrate co-contaminants, and general water quality parameters. Preliminary analysis of archival water district data from both basins suggests positive correlations of nitrate with Ca+2, Mg+2 and bicarbonate and negative correlation with pH. In the Llagas Basin, a negative correlation also exists between nitrate and temperature. Flow path-oriented reactive transport modeling is being explored as a tool to aid in the identification of both the sources of nitrate and evidence for denitrification in both basins

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

    Science.gov (United States)

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

    2012-05-01

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

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

    Directory of Open Access Journals (Sweden)

    FRANCISCO ROTHHAMMER

    2002-03-01

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

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

    Science.gov (United States)

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

    2011-12-01

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

  15. Tectonic Subsidence Analysis of the Pearl River Mouth Basin, Northern South China Sea

    Science.gov (United States)

    Tang, X.; Huang, S. S. X. E. C.; Zhuang, W.; LIU, Z.; Duan, W.; Hu, S.

    2015-12-01

    The Pearl River Mouth Basin (PRMB hereafter) in the northern margin of the South China Sea has attracted great attention not only because of its special tectonic location but also for its abundant hydrocarbon resources. Tectonic evolution controls the petroleum geological condition of hydrocarbon-bearing basins. Efforts have been made to understand the tectonic evolution of this basin. However, many issues about the tectonic features and the evolution process of this basin, such as the age of the breakup unconformities and the anomalously accelerated subsidence during the post-rifting stage, remain controversial. Here we employ tectonic subsidence analysis of sedimentary basins, a technique of removing isostatic loading and compaction effects by back-stripping, to investigate the tectonic controls on the basin formation of the PRMB. We performed the analysis on 4 drill wells and 43 synthetic wells constructed based on recently acquired seismic profiles. The result shows that tectonic subsidence in the eastern sags of the PRMB began to decrease at ~30Ma while in the western sags the onset was ~23.8Ma. This suggests that the break-up time i.e. the end of rifting in the PRMB is earlier in the eastern sags than in the western sags. Abnormally accelerated tectonic subsidence occurred between 17.5-16.4Ma during the post-rifting stage, at an average subsidence rate as high as 301.9m/Ma. This phenomenon discriminates the PRMB from the category of classical Atlantic passive continental marginal basins, of which the tectonic subsidence during the post-rifting stage decays exponentially. The main objective of this paper is to provide insights into the geological and geodynamic evolution of the PRMB. The result bears significance to hydrocarbon exploration in this region.

  16. Miocene woods from the Qaidam Basin on northern Qinghai-Tibet Plateau with implications for paleoenvironmental change

    Science.gov (United States)

    Cheng, Ye-Ming; Yang, Xiao-Nan

    2016-02-01

    The Qaidam Basin with the most complete Cenozoic sedimentary preservation in northern Qinghai-Tibet Plateau is a key area for studying uplift and environmental change of the plateau. Three types of woods, Ulmus (Ulmaceae), Leguminosae (?) (angiosperm) and Cupressaceae (gymnosperm) were recognized from the large-scale preservation of fossil woods in late Miocene Shang Youshashan Formation in northern Qaidam Basin on the Qinghai-Tibet Plateau. Both investigations of their Nearest Living Relatives (NLRs) and previous grassland mammal evidences suggest that there have been temperate deciduous broad-leaved forest and needle-leaved forest with grass in northern Qaidam Basin during the late Miocene in contrast to the desert vegetation found there nowadays. The presence of the ancient forest steppe further implies that the southern part of the plateau used to be adequately low, so that the Indian and East Asian monsoons could approach the northern area and to accommodate the vegetation in late Miocene.

  17. Hydrogeochemistry of high-fluoride groundwater at Yuncheng Basin, northern China

    International Nuclear Information System (INIS)

    Hydrogeochemical and environmental isotope methods were integrated to delineate the spatial distribution and enrichment of fluoride in groundwater at Yuncheng Basin in northern China. One hundred groundwater samples and 10 Quaternary sediment samples were collected from the Basin. Over 69% of the shallow groundwater (with a F− concentration of up to 14.1 mg/L), 44% of groundwater samples from the intermediate and 31% from the deep aquifers had F− concentrations above the WHO provisional drinking water guideline of 1.5 mg/L. Groundwater with high F− concentrations displayed a distinctive major ion chemistry: Na-rich and Ca-poor with a high pH value and high HCO3− content. Hydrochemical diagrams and profiles and hydrogen and oxygen isotope compositions indicate that variations in the major ion chemistry and pH are controlled by mineral dissolution, cation exchange and evaporation in the aquifer systems, which are important for F− mobilization as well. Leakage of shallow groundwater and/or evaporite (gypsum and mirabilite) dissolution may be the major sources for F− in groundwater of the intermediate and deep aquifers. - Highlights: • High-F− groundwater widely occurs in Yuncheng Basin of northern China. • High-F− groundwater is Na and HCO3-rich and Ca-poor, with high pH. • Major hydrogeochemical processes are mineral dissolution, ion exchange and evaporation. • Shallow groundwater leakage/evaporite dissolution may cause F enrichment in lower aquifers

  18. Prospect analysis for sandstone-type uranium mineralization in the northern margin of Qaidam basin

    International Nuclear Information System (INIS)

    Affected by the regional geological structural evolution, a set of sedimentary structure, i.e. the construction of coal-bearing classic rocks which is in favor of the sandstone-type uranium mineralization has deposited in the northern margin of Qaidam Basin since Meso-Cenozoic. A NWW thrust nappe tectonic belt, i.e. the ancient tectonic belt which is the basis for the development of ancient interlayer oxidation zone formed by the tectonic reverse in late Jurassic and Cretaceous. The Mid and late Jurassic layer was buried by the weak extension in Paleogene and the depression in early Neogene. The extrusion reversal from late Neogene to Quaternary made the basin into the development era of the modern interlayer oxidation zone. It can be concluded that the layer of the northern margin of Qaidam Basin has the premise for the formation of sandstone-type uranium ore. Based on the analysis of the characteristics of the thrust belt, the structure of the purpose layer, the sand body, the hydrogeology, the interlayer oxidation zone and uranium mineralization, the results indicated that the ancient interlayer oxidation zone is the prospecting type of sandstone-type uranium ore. Beidatan and the east of Yuqia are the favorable prospective area of sandstone-type uranium mineralization. (authors)

  19. Characteristics and genesis of clay minerals in the northern margin of the Qaidam Basin

    Institute of Scientific and Technical Information of China (English)

    Wang Linlin; Jiang Bo; Peng Dehua; Yin Chengming; Zeng Chunlin

    2011-01-01

    In order to develop appropriate reservoir protection measures in the northern margin of the Qaidam Basin and improve its oil and gas recovery efficiency, characteristics of clay minerals from eleven clay rock samples from the northern margin of the Qaidam Basin were investigated using X-ray diffraction analysis, the Scanning Electron Microscope (SEM) and energy spectrum analysis. Clay mineral composition and distribution characteristics of the main hydrocarbon reservoirs, I.e., from the Jurassic and Paleogene-Neogene, were explored. We analyzed the main factors which affected these attributes. The results show that the major clay minerals in the northern margin are chlorite, kaolinite, illite, smectite and illite/smectite inter-stratified minerals, Illite is the most widely spread clay mineral in this area.Chlorite is mainly found in the entire Neogene and in shallow horizons of the Paleogene. Smectite is enriched in the shallow Paleogene-Neogene. There are large amounts of kaolinite and illite/smectite inter-stratified minerals in the Jurassic. The major factors affecting the different development of clay minerals in the region are properties of parent rocks, paleoclimate and paleowater media conditions,diagenesis transformation, tectonic and terrain conditions.

  20. Evidence for a broadly distributed Samoan-plume signature in the northern Lau and North Fiji Basins

    Science.gov (United States)

    Price, Allison A.; Jackson, Matthew G.; Blichert-Toft, Janne; Hall, Paul S.; Sinton, John M.; Kurz, Mark D.; Blusztajn, Jerzy

    2014-04-01

    enrichment of lavas in the northern Lau Basin may reflect the influx of Samoan-plume mantle into the region. We report major and trace element abundances and He-Sr-Nd-Hf-Pb-isotopic measurements for 23 submarine volcanic glasses covering 10 locations in the northern Lau and North Fiji Basins, and for three samples from Wallis Island, which lies between Samoa and the Lau Basin. These data extend the western limit of geochemical observations in the Basins and improve the resolution of North-South variations in isotopic ratios. The Samoan hot spot track runs along the length of the northern trace of the Lau and North Fiji Basins. We find evidence for a Samoan-plume component in lavas as far West as South Pandora Ridge (SPR), North Fiji Basin. Isotopic signatures in SPR samples are similar to those found in Samoan Upolu shield lavas, but show a slight shift toward MORB-like compositions. We explain the origin of the enriched signatures by a model in which Samoan-plume material and ambient depleted mantle undergo decompression melting during upwelling after transiting from beneath the thick Pacific lithosphere to beneath the thin lithosphere in the northern Lau and North Fiji Basins. Other lavas found in the region with highly depleted isotopic signatures may represent isolated pockets of depleted mantle in the basins that evaded this enrichment process. We further find that mixing between the two components in our model, a variably degassed high-3He/4He Samoan component and depleted MORB, can explain the diversity among geochemical data from the northern Lau Basin.

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

    Science.gov (United States)

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

    2014-12-01

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

  2. Structural style and Basin Formation in Deep-water Area of Northern South China Sea

    Science.gov (United States)

    di, Z.; Zhen, S.; Xiong, P.; Min, C. C.

    2007-12-01

    In the deep-water area of northern South China Sea (SCS) developed a series of sedimentary basins. Active exploration for deep-water hydrocarbon has begun in these areas since this century. The well LW3-1-1 at water depth of 1480m in the BaiYun Sag (BYS) of the Pearl River Mouth Basin in 2006 discovered 56m layer of pure gas, demonstrated the good hydrocarbon potential of the area. Wide-angle seismic profiling has verified the transitional type of crust in the slope areas. The Moho surface shoals step-by-step from 30-29km under the shelf, ~15 km under the slope, and ~12km under the abyssal plain. Moho also rises beneath depocenters, mirroring the shape of sedimentary basement. The crustal thickness at the center of the BYS is Pacific Ocean towards the East Eurasian margin. The stress field in the East Eurasian margin changed abruptly in Late Cretaceous. Rifting started in the entire margin and eventually led to the opening of the SCS in late Early Oligocene. Large sedimentary basins developed in the margins of the SCS. Paleogene lacustrine sediments contain hydrocarbon sources, while traps are mostly found in Neogene marine strata. The structure of the northern SCS shows clear W-E variation, divided into NE-, NEE-, and NE-trending segments by two major NW-SE transfer faults. The Southern Depression of the Qiongdongnan Basin to the west is characterized by NE-trending half grabens. The BYS at the central segment is characterized by NEE-trending composite grabens and down warps with relatively small offset of boundary faults. To the east the Chaoshan Depression is composed of Mesozoic strata under very thin (deep-water basins is different from that of shallow-water basins. A study is ongoing to explore the basin formation mechanism, taking into account of the factors of abnormal lithosphere rheology, active mantle underplating and magmatic heating, lower crust flow, as well as the superposition of later extensional events. The study is supported by NSFC grants

  3. Federally owned coal and Federal lands in the northern and central Appalachian Basin coal regions

    Energy Technology Data Exchange (ETDEWEB)

    Susan J. Tewalt

    2002-02-01

    The US Geological Survey (USGS) assessed five coals beds or coal zones in the northern and central Appalachian Basin coal regions for the National Coal Resource Assessment: the Pittsburgh coal bed, the Upper Freeport coal bed, the Fire Clay coal zone, the Pond Creek coal zone, and the Pocahontas No. 3 coal bed. The assessment produced stratigraphic and geochemical databases and digital coal maps, or models, which characterized the coal beds and coal zones. Using the assessment models, the USGS estimated original and remaining (unmined) resources for these coal beds or zones. The Appalachian Basin assessment was conducted in collaboration with the State geological surveys of West Virginia, Pennsylvania, Ohio, Maryland, Kentucky, and Virginia. 3 refs., 7 figs.

  4. Coal resources of selected coal beds and zones in the northern and central Appalachian Basin

    Energy Technology Data Exchange (ETDEWEB)

    Leslie Ruppert; Susan Tewalt; Linda Bragg

    2002-02-01

    The U.S. Geological Survey (USGS) is completing a National Coal Resource Assessment of five coal-producing regions of the United States, including the Appalachian Basin. The USGS, in cooperation with the State geological surveys of Kentucky, Maryland, Ohio, Pennsylvania, Virginia, and West Virginia, has completed a digital coal resource assessment of five of the top-producing coal beds and coal zones in the northern and central Appalachian Basin coal regions -- the Pittsburgh coal bed, the Upper Freeport coal bed, the Fire Clay and Pond Creek coal zones, and the Pocahontas No. 3 coal bed. Of the 93 billion short tons of original coal in these units, about 66 billion short tons remain. 2 refs., 5 figs., 2 tabs.

  5. Visan miospore biostratigraphy and correlation of the Poti Formation (Parnaba Basin, northern Brazil).

    Science.gov (United States)

    Melo; Loboziak

    2000-10-01

    The Poti Formation, which consists mainly of sandstones with minor proportions of carbonaceous shales and other siliciclastic lithologies, represents all the Viséan strata thus far recorded in the Parnaíba Basin, northern Brazil.Well-preserved miospores featuring species with both Southern Euramerican and Gondwanan affinities have been recovered from this formation in four well sections. The most characteristic species are listed in this paper, and brief systematic descriptions are presented for the most significant species, along with comments on their biostratigraphy. A new generic combination is proposed: Cordylosporites magnidictyus (Playford and Helby) Loboziak and Melo comb. nov. Comparisons with miospores illustrated from the Grand Erg Occidental, Algerian Sahara, are tentatively proposed.In terms of the Western European Carboniferous palynozonation, miospore assemblages from the Poti Formation are assignable to the Perotrilites tessellatus-Schulzospora campyloptera (TC)-Raistrickia nigra-Triquitrites marginatus (NM) zonal range. This corresponds to the upper part of the Holkerian and the whole Asbian, which are British regional stages for the lower to middle parts of the upper Viséan. The Viséan age formerly attributed to biostratigraphic interval XII of Petrobras' regional palynostratigraphic scheme is therefore confirmed. As already noted in our recent investigations of the Faro Formation in the Amazon Basin and equivalent strata of the Solimões Basin, latest Tournaisian and early to middle Viséan sections are either absent or barren of characteristic miospores in the Parnaíba Basin as well. PMID:11042330

  6. Latest Miocene to Quaternary deformation in the southern Chaiwopu Basin, northern Chinese Tian Shan foreland

    Science.gov (United States)

    Lu, Honghua; Wang, Zhen; Zhang, Tianqi; Zhao, Junxiang; Zheng, Xiangmin; Li, Youli

    2015-12-01

    Basinward propagation of fold and thrust belts is a crucial geological process accommodating Cenozoic crustal shortening within the India-Eurasia collision zone. Anticlinal growth strata in the southern Chaiwopu Basin (a piggyback basin) of the northern Chinese Tian Shan foreland record basinward encroachment of the Tian Shan along the Junggar Frontal Thrust Fault. A new magnetostratigraphic section constrains the onset of syntectonic growth strata at circa 6.4 Ma and suggests synchronous basinward thrusting and propagation of the Tian Shan. The intense alluviation in the southern Chaiwopu Basin ceased at circa 0.55 Ma due to significant anticlinal growth and its resultant river incision. More recent anticlinal growth and deformation during the late Quaternary are revealed by folded river terraces developing across the anticline. The terrace height profile indicates that terrace T1H has been vertically offset about 0.6 m by thrust faulting since its formation at about 7 Ka. The stratigraphic and geomorphic data presented in this work are helpful to understand the initiation of thrust-related folding, as well as aggradation and subsequent incision, in foreland basins of the Tian Shan in relation to the India-Asia collision.

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

    Science.gov (United States)

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

    2015-04-01

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

  8. Geophysical observations on northern part of Georges Bank and adjacent basins of Gulf of Maine

    Science.gov (United States)

    Oldale, R.N.; Hathaway, J.C.; Dillon, William P.; Hendricks, J.D.; Robb, James M.

    1974-01-01

    Continuous-seismic-reflection and magnetic-intensity profiles provide data for inferences about the geology of the northern part of Georges Bank and the basins of the Gulf of Maine adjacent to the bank. Basement is inferred to be mostly sedimentary and volcanic rocks of Paleozoic age that were metamorphosed and intruded locally by felsic and mafic plutons near the end of the Paleozoic Era. During Late Triassic time, large fault basins formed within the Gulf of Maine and probably beneath Georges Bank. The fault basins and a possible major northeast-trending fault zone beneath the northern part of the bank probably formed as a result of the opening Atlantic during the Mesozoic. Nonmarine sediments, associated with mafic flows and intrusive rocks, were deposited in the fault basins as they formed. The upper surface of the Triassic and pre-Triassic rocks that comprise basement is an unconformity that makes up much of the bottom of the Gulf of Maine. Depth to the basement surface beneath the gulf differ greatly because of fluvial erosion in Tertiary time and glacial erosion in Pleistocene time. Beneath the northern part of Georges Bank the basement surface is smoother and slopes southward. Prominent valleys, cut before Late Cretaceous time, are present beneath this part of the bank. Cretaceous, Tertiary, and possibly Jurassic times were characterized by episodes of coastal-plain deposition and fluvial erosion. During this time a very thick wedge of sediment, mostly of Jurassic(?) and Cretaceous ages, was deposited on the shelf. Major periods of erosion took place at the close of the Cretaceous and during the Pliocene. Fluvial erosion during the Pliocene removed much of the coastal-plain sedimentary wedge and formed the Gulf of Maine. Pleistocene glaciers eroded all but a few remnants of the coastal-plain sediments within the gulf and deposited a thick section of drift against the north slope of Georges Bank and a thin veneer of outwash on the bank. Marine sediments were

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

    Science.gov (United States)

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

    2010-12-01

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

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

    International Nuclear Information System (INIS)

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

  11. Recognition of relict Mesozoic Dongsha Basin in the northern margin, South China Sea and its implication

    Science.gov (United States)

    Yan, Pin; Wang, Yanlin

    2015-04-01

    The Pearl River Mouth Basin (PRMB) is dominated by NE-trending rift architecture produced mainly during Cenozoic Era. It comprises a series of grabens built up with thick Paleogene and thick Neogene sediments, up to 12000 m, and dividing basement highs composing Yanshanian granitic rocks. Though previously considered as one constituent part of PRMB in the southeast, Dongsha Basin displays major differences in sedimentary architecture and tectonic framework. Firstly, Dongsha Basin is characterized by a prominent angular unconformity, interpreted as a spectacular planation or rough erosion surface which separates the sediment column into two distinct parts. It is interpreted with accumulating seismic and drill data that the underlying strata comprise Early Cretaceous terrestrial, Jurassic marine and possibly Triassic sedimentary rocks totaling to 4~9 km thick, whereas the overlying strata are very thin (usually 0.5~1 km in whole) composing mainly Neogene sediments. The major sedimentary hiatus between them corresponds to the Late Cretaceous to mid-Miocene Epoch, well during the rifting to spreading process when the PRMB developed. Secondly, unlike the PRMB, the Dongsha Basin has suffered considerably less extension except its boundary areas, and actually remained as a relatively stable block though Cenozoic Era. Moreover, there are a few compressive open fold structures within the buried Mesozoic strata over the central Dongsha Basin. These folds trend in NNE and are characterized mostly by few minor growing upthrust faults with offsets in the order of few tens to hundreds meter. The upthrust faults dipped mostly southeastward against the northwestward subduction of paleo-Pacific plate as postulated in other previous study. The blind folds featured more like back-thrust growth tectonics, formed a broad NNE-SSW trending belt, obviously oblique to the trend of northern margin of the South China Sea and the PRMB as well. In a few recent models, the most prominent

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

    Directory of Open Access Journals (Sweden)

    DAVID VELIZ

    2000-12-01

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

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

    Directory of Open Access Journals (Sweden)

    César A. Méndez

    2009-12-01

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

  14. Extraordinarily thick-boned fish linked to the aridification of the Qaidam Basin (northern Tibetan Plateau).

    Science.gov (United States)

    Chang, Meemann; Wang, Xiaoming; Liu, Huanzhang; Miao, Desui; Zhao, Quanhong; Wu, Guoxuan; Liu, Juan; Li, Qiang; Sun, Zhencheng; Wang, Ning

    2008-09-01

    Scattered with numerous salt lakes and approximately 2,700-3,200 m above sea level, the giant Qaidam inland basin on the northern Tibetan Plateau has experienced continuing aridification since the beginning of the Late Cenozoic as a result of the India-Asia plate collision and associated uplift of the Tibetan Plateau. Previous evidence of aridification comes mainly from evaporite deposits and salinity-tolerant invertebrate fossils. Vertebrate fossils were rare until recent discoveries of abundant fish. Here, we report an unusual cyprinid fish, Hsianwenia wui, gen. et sp. nov., from Pliocene lake deposits of the Qaidam Basin, characterized by an extraordinarily thick skeleton that occupied almost the entire body. Such enormous skeletal thickening, apparently leaving little room for muscles, is unknown among extant fish. However, an almost identical condition occurs in the much smaller cyprinodontid Aphanius crassicaudus (Cyprinodonyiformes), collected from evaporites exposed along the northern margins of the Mediterranean Sea during the Messinian desiccation period. H. wui and A. crassicaudus both occur in similar deposits rich in carbonates (CaCO(3)) and sulfates (CaSO(4)), indicating that both were adapted to the extreme conditions resulting from the aridification in the two areas. The overall skeletal thickening was most likely formed through deposition of the oversaturated calcium and was apparently a normal feature of the biology and growth of these fish. PMID:18757732

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

    Directory of Open Access Journals (Sweden)

    Héctor A. Vargas

    2015-06-01

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

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

    Science.gov (United States)

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

    2008-03-01

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

  17. Hydrogeochemistry of high-fluoride groundwater at Yuncheng Basin, northern China

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chengcheng [State Key Laboratory of Biogeology and Environmental Geology and School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Gao, Xubo, E-mail: xubo.gao.cug@gmail.com [State Key Laboratory of Biogeology and Environmental Geology and School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); University of Texas at Austin, Austin, TX, 78705 (United States); Wang, Yanxin, E-mail: yx.wang@cug.edu.cn [State Key Laboratory of Biogeology and Environmental Geology and School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China)

    2015-03-01

    Hydrogeochemical and environmental isotope methods were integrated to delineate the spatial distribution and enrichment of fluoride in groundwater at Yuncheng Basin in northern China. One hundred groundwater samples and 10 Quaternary sediment samples were collected from the Basin. Over 69% of the shallow groundwater (with a F{sup −} concentration of up to 14.1 mg/L), 44% of groundwater samples from the intermediate and 31% from the deep aquifers had F{sup −} concentrations above the WHO provisional drinking water guideline of 1.5 mg/L. Groundwater with high F{sup −} concentrations displayed a distinctive major ion chemistry: Na-rich and Ca-poor with a high pH value and high HCO{sub 3}{sup −} content. Hydrochemical diagrams and profiles and hydrogen and oxygen isotope compositions indicate that variations in the major ion chemistry and pH are controlled by mineral dissolution, cation exchange and evaporation in the aquifer systems, which are important for F{sup −} mobilization as well. Leakage of shallow groundwater and/or evaporite (gypsum and mirabilite) dissolution may be the major sources for F{sup −} in groundwater of the intermediate and deep aquifers. - Highlights: • High-F{sup −} groundwater widely occurs in Yuncheng Basin of northern China. • High-F{sup −} groundwater is Na and HCO{sub 3}-rich and Ca-poor, with high pH. • Major hydrogeochemical processes are mineral dissolution, ion exchange and evaporation. • Shallow groundwater leakage/evaporite dissolution may cause F enrichment in lower aquifers.

  18. Towards large scale modelling of wetland water dynamics in northern basins.

    Science.gov (United States)

    Pedinotti, V.; Sapriza, G.; Stone, L.; Davison, B.; Pietroniro, A.; Quinton, W. L.; Spence, C.; Wheater, H. S.

    2015-12-01

    Understanding the hydrological behaviour of low topography, wetland-dominated sub-arctic areas is one major issue needed for the improvement of large scale hydrological models. These wet organic soils cover a large extent of Northern America and have a considerable impact on the rainfall-runoff response of a catchment. Moreover their strong interactions with the lower atmosphere and the carbon cycle make of these areas a noteworthy component of the regional climate system. In the framework of the Changing Cold Regions Network (CCRN), this study aims at providing a model for wetland water dynamics that can be used for large scale applications in cold regions. The modelling system has two main components : a) the simulation of surface runoff using the Modélisation Environmentale Communautaire - Surface and Hydrology (MESH) land surface model driven with several gridded atmospheric datasets and b) the routing of surface runoff using the WATROUTE channel scheme. As a preliminary study, we focus on two small representative study basins in Northern Canada : Scotty Creek in the lower Liard River valley of the Northwest Territories and Baker Creek, located a few kilometers north of Yellowknife. Both areas present characteristic landscapes dominated by a series of peat plateaus, channel fens, small lakes and bogs. Moreover, they constitute important fieldwork sites with detailed data to support our modelling study. The challenge of our new wetland model is to represent the hydrological functioning of the various landscape units encountered in those watersheds and their interactions using simple numerical formulations that can be later extended to larger basins such as the Mackenzie river basin. Using observed datasets, the performance of the model to simulate the temporal evolution of hydrological variables such as the water table depth, frost table depth and discharge is assessed.

  19. Ellipticity of Rayleigh waves in basin and hard-rock sites in Northern Italy

    Science.gov (United States)

    Berbellini, Andrea; Morelli, Andrea; Ferreira, Ana M. G.

    2016-07-01

    We measure ellipticity of teleseismic Rayleigh waves at 95 seismic stations in Northern Italy, for wave period between 10 and 110 s, using an automatic technique and a large volume of high-quality seismic recordings from over 500 global earthquakes that occurred in 2008-2014. Northern Italy includes a wide range of crustal structures, from the wide and deep Po Plain sedimentary basin to outcropping sedimentary and crystalline rocks in the Northern Apennines and Alps. It thus provides an excellent case for studying the influence of shallow earth structure on polarization of surface waves. The ellipticity measurements show excellent spatial correlation with geological features in the region, such as high ellipticity associated with regions of low seismic velocity in the Po Plain and low ellipticity values in faster, hard rock regions in the Alps and Apennine mountains. Moreover, the observed ellipticity values also relate to the thickness of the basement, as highlighted by observed differences beneath the Alps and the Apennines. Comparison between observations and predicted ellipticity from a reference crustal model of the region show substantial fit, particularly for T ˜ 38 s data. Discrepancy for shorter wave period suggests that slight modifications of the model are needed, and that the ellipticity measurements could help to better constrain the shallow crustal structure of the region. Predictions for the Po Plain are larger than the observations by a factor of four or more and transition from retrograde to prograde Rayleigh wave motion at the surface for periods of T ˜ 10-13 s is predicted for seismic stations in the plain. Analysis of corresponding real data indicates a possible detection of teleseismic prograde particle motion, but the weak teleseismic earthquake signals are mixed with ambient noise signals at the predicted, short, transition periods. Detection of the period of polarity inversion from the joint analysis of earthquake and ambient noise

  20. Ellipticity of Rayleigh waves in basin and hard-rock sites in Northern Italy

    Science.gov (United States)

    Berbellini, Andrea; Morelli, Andrea; Ferreira, Ana M. G.

    2016-04-01

    We measure ellipticity of teleseismic Rayleigh waves at 95 seismic stations in Northern Italy, for wave period between 10 s and 110 s, using an automatic technique and a large volume of high-quality seismic recordings from over 500 global earthquakes that occurred in 2008-2014. Northern Italy includes a wide range of crustal structures, from the wide and deep Po Plain sedimentary basin to outcropping sedimentary and cristalline rocks in the Northern Apennines and Alps. It thus provides an excellent case for studying the influence of shallow earth structure on polarisation of surface waves. The ellipticity measurements show excellent spatial correlation with geological features in the region, such as high ellipticity associated with regions of low seismic velocity in the Po Plain and low ellipticity values in faster, hard rock regions in the Alps and Apennine mountains. Moreover, the observed ellipticity values also relate to the thickness of the basement, as highlighted by observed differences beneath the Alps and the Apennines. Comparison between observations and predicted ellipticity from a reference crustal model of the region show substantial fit, particularly for T ˜ 38 s data. Discrepancy for shorter wave period suggests that slight modifications of the model are needed, and that the ellipticity measurements could help to better constrain the shallow crustal structure of the region. Predictions for the Po Plain are larger than the observations by a factor of four or more and transition from retrograde to prograde Rayleigh wave motion at the surface for periods of T ˜ 10-13 s is predicted for seismic stations in the Plain. Analysis of corresponding real data indicates a possible detection of teleseismic prograde particle motion, but the weak teleseismic earthquake signals are mixed with ambient noise signals at the predicted, short, transition periods. Detection of the period of polarity inversion from the joint analysis of earthquake and ambient noise

  1. The Millstone Grit Group (Pennsylvanian) of the Northumberland-Solway Basin and Alston Block of northern England

    OpenAIRE

    Waters, C.N; Millward, D.; C. W. Thomas

    2014-01-01

    In the Northumberland–Solway Basin and Alston Block of northern England, some aspects of the stratigraphical and sedimentological relationships between the Millstone Grit Group, the Stainmore Formation (Namurian part of the Yoredale Group) and the Westphalian Pennine Coal Measures Group are uncertain. Also, confusion has resulted from discontinuation of Millstone Grit as a formal lithostratigraphical term north of the Stainmore Basin. This paper presents the evidence for, and describes the na...

  2. A long lacustrine record from the Piànico-Sèllere Basin (Middle-Late Pleistocene, Northern Italy)

    OpenAIRE

    A. Moscariello; Ravazzi, C.; Achim Brauer; C. Mangili; Chiesa, S.; Rossi, S.; J.-L. de Beaulieu; M. Reille

    2000-01-01

    The stratigraphical succession of the Piànico-Sèllere Basin (Northern Italy) represents an exceptionally well preserved sedimentary assemblage which formed in a closed lake basin during the Middle–Upper Pleistocene. These deposits are grouped into the hereby proposed "Piànico Formation". This includes four lacustrine, fine-grained, laminated lithostratigraphical units containing a 10.5 m thick interval of well preserved varved carbonates. The lacustrine units are coeval, and laterally heterop...

  3. Helium Isotope Variations in the Northern Lau and North Fiji Basins

    Science.gov (United States)

    Lupton, J. E.; Arculus, R. J.; Jenner, F. E.; Evans, L.; Greene, R.

    2012-12-01

    Recent measurements of submarine basalts from the Northern Lau Basin exhibit a fascinating pattern in the helium isotopes. In particular, basalts along the NW Lau Spreading Center and the Rochambeau Rifts (NWLSC-RR) all have elevated 3He/4He ratios ranging from 11 to 28 Ra, much higher than the MORB-like values of 7 - 9 Ra that might be expected for a typical back-arc spreading center (Lupton et al, GRL 2009) (R = 3He/4He and Ra = Rair = 1.39E-6). This has been interpreted as indicating the presence of a mantle plume component, possibly from the Samoan hotspot, which has somehow intruded into the northern Lau Basin. Furthermore, neon isotopes analyzed in this same suite of basalts exhibit enrichments in 21Ne/22Ne and 20Ne/22Ne distinct from MORB neon and similar to neon isotopes measured in Samoan lavas (Lupton et al., GRL, 2012), further evidence for intrusion of a Samoan plume component. Surprisingly, this hotspot component is only evident along the NWLSC-RR, while samples from seafloor basalts and submarine hydrothermal fluids in the NE Lau Basin have MORB-like values or lower, varying from 6.5 to 8.5 Ra. However, very few samples have been collected to the west of the NWLSC-RR, and the question thus remains as to the origin and extent of this 3He-rich component in the northern Lau Basin. Recently, expedition SS2012 of the R/V Southern Surveyor collected submarine rock samples from the volcanic zones in the northwestern Lau Basin and North Fiji Basin. These samples have 3He/4He ratios ranging from 9.0 up to 14.6 Ra, above the range for normal MORBs. Of particular interest is the zone immediately to the west of the Rochambeau Rifts. Samples from the SE Futuna Volcanic Zone and from the Futuna Spreading Center have 3He/4He varying from 9.2 to 10.6 Ra. Farther west, samples from the West Cikobia Volcanic Zone due north of the Fiji Islands have helium with 9.3 up to 12.2 Ra. Still farther west in the Fiji Basin at 17S, 174E, samples dredged from the NE Fiji Triple

  4. Water masses of the northern part of the Iceland Basin in the late Pleistocene

    Science.gov (United States)

    Lukashina, N. P.

    2013-02-01

    A core of bottom sediments AMK-4438 with a length of 320 cm was taken in the North-Eastern part of the Iceland Basin from the depth of 2240 m. The continuous sampling (every 2 cm) made it possible to study the core using the principle of high-resolving paleoceanology. For the stratigraphic partition of the core, we applied the paleotemperature analysis by planktonic foraminifera and carbonate analysis; the distribution of the iceberg rafted debris (IRD) was studied. As a result, nine isotopic stages were distinguished. The change in the complexes of benthic foraminifera indicates that the present-day deepwater circulation in the North-Eastern part of the Iceland Basin had no analogs in earlier glacial periods, including the MIS 5 age. During almost 300 ka, there were relatively warm, rich in nutrients, and poor in oxygen water masses. The formation of the modern Northern-Eastern deep water in the Iceland Basin began in the Bolling-Allerod 14 ka B.P.

  5. Formation Laws of Inorganic Gas Pools in the Northern Jiangsu Basin

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the Northern Jiangsu basin there are high pure CO2 gas pools, low condensed oil-containing CO2 gas pools, high condensed oil-containing CO2 gas pools and He-containing natural gas pools, with the d 13Cco2 (PDB) values ranging from - 2.87to - 6.50 3He/4He 3.71×10- 6 to 6.42×10- 6, R/Ra 2.64 to 4.5, 40Ar/36Ar 705 to 734, belonging to typical mantle source inorganic gas pools which are related to young magmatic activity. The gas layers occur in two major reservoir-caprock systems, the terrestrial Meso-Cenozoic clastic rock system and the marine Meso-Palaeozoic carbonate rock-clastic rock system. Controlled by the difference in the scale of traps in the two reservoir-caprock systems, large and medium-scale inorganic gas pools are formed in the marine Meso-Palaeozoic Group and only small ones are formed in the terrestrial Meso-Cenozoic strata. Inorganic gas pools in this basin are distributed along the two deep lithospheric faults on the west and south boundaries of the basin. Gas pools are developed at the intersected part of the ENE-trending faults that control the half graben and the E-W tenso-shear faults, mainly distributed near the Es1, Ny1 and Ny2-Q basalt eruption centres.

  6. An isotope hydrochemical approach to understand fluoride release into groundwaters of the Datong Basin, Northern China.

    Science.gov (United States)

    Su, Chunli; Wang, Yanxin; Xie, Xianjun; Zhu, Yapeng

    2015-04-01

    The hydrogeochemical and isotopic investigations of high fluoride (up to 8.26 mg L(-1)) groundwater in the Datong Basin, Northern China were carried out in order to evaluate the geochemical controls on fluoride enrichment. The groundwater fluoride concentration tends to increase along with the regional groundwater flow path away from the basin margins, towards the central parts of the basin. Groundwater with high F concentrations has a distinctive major ion chemistry, being generally HCO3(-)-rich, Na-rich, Ca-poor, and having weak alkaline pH values (7.2 to 8.2) and Na-HCO3 waters. These data indicate that variations in the groundwater major ion chemistry and possibly pH, which are controlled by water-rock interaction processes in the aquifer, are important in mobilizing F. Positive correlations between fluoride with lithogenic sodium (LNa) and HCO3(-) in groundwater show that the high fluoride content and alkaline sodic characteristics of groundwater result from dissolution of fluorine-bearing minerals. The occurrence and behavior of fluorine in groundwater are mainly controlled by fluorite precipitation as a function of Ca(2+) concentration. A positive correlation between fluoride and δ(18)O, low F(-)/Cl(-) ratios, and the low tritium level in the fluoride-rich groundwater indicate the effects of long-term water-rock interactions and intensive evapotranspiration. PMID:25743227

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

    Science.gov (United States)

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

    2014-12-01

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

  8. Adaptation to changing water resources in the Ganges basin, northern India

    International Nuclear Information System (INIS)

    An ensemble of regional climate model (RCM) runs from the EU HighNoon project are used to project future air temperatures and precipitation on a 25 km grid for the Ganges basin in northern India, with a view to assessing impact of climate change on water resources and determining what multi-sector adaptation measures and policies might be adopted at different spatial scales. The RCM results suggest an increase in mean annual temperature, averaged over the Ganges basin, in the range 1-4 oC over the period from 2000 to 2050, using the SRES A1B forcing scenario. Projections of precipitation indicate that natural variability dominates the climate change signal and there is considerable uncertainty concerning change in regional annual mean precipitation by 2050. The RCMs do suggest an increase in annual mean precipitation in this region to 2050, but lack significant trend. Glaciers in headwater tributary basins of the Ganges appear to be continuing to decline but it is not clear whether meltwater runoff continues to increase. The predicted changes in precipitation and temperature will probably not lead to significant increase in water availability to 2050, but the timing of runoff from snowmelt will likely occur earlier in spring and summer. Water availability is subject to decadal variability, with much uncertainty in the contribution from climate change. Although global social-economic scenarios show trends to urbanization, locally these trends are less evident and in some districts rural population is increasing. Falling groundwater levels in the Ganges plain may prevent expansion of irrigated areas for food supply. Changes in socio-economic development in combination with projected changes in timing of runoff outside the monsoon period will make difficult choices for water managers. Because of the uncertainty in future water availability trends, decreasing vulnerability by augmenting resilience is the preferred way to adapt to climate change. Adaptive policies are

  9. Early life history of the northern pikeminnow in the lower Columbia River basin

    Science.gov (United States)

    Gadomski, D.M.; Barfoot, C.A.; Bayer, J.M.; Poe, T.P.

    2001-01-01

    The northern pikeminnow Ptychocheilus oregonensis is a large, native cyprinid in the Columbia River basin that has persisted in spite of substantial habitat alterations. During the months of June to September 1993-1996, we investigated the temporal and spatial patterns of northern pikeminnow spawning, along with describing larval drift and characterizing larval and early juvenile rearing habitats in the lower Columbia River (the John Day and Dalles reservoirs and the free-flowing section downstream of Bonneville Dam) as well as in the lower sections of two major tributaries (the John Day and Deschutes rivers). The density of newly emerged drifting larvae was higher in dam tailraces (a mean of 7.7 larvae/100 m3 in surface tows) than in the lower reservoirs (0.3 larvae/100 m3), indicating that tailraces were areas of more intense spawning. Density was particularly high in the Bonneville Dam tailrace (15.1 larvae/100 m3), perhaps because adult northern pikeminnow are abundant below Bonneville Dam and this is the first tailrace and suitable main-stem spawning habitat encountered during upriver spawning migrations. Spawning also occurred in both of the tributaries sampled but not in a backwater. Spawning in the Columbia River primarily took place during the month of June in 1993 and 1994, when the water temperature rose from 14??C to 18??C, but occurred about 2 weeks later in 1995 and 1996, possibly because of cooler June water temperature (14-15??C) in these years. The period of drift was brief (about 1-3 d), with larvae recruiting to shallow, low-velocity shorelines of main-channel and backwater areas to rear. Larvae reared in greatest densities at sites with fine sediment or sand substrates and moderate- to high-density vegetation (a mean density of 92.1 larvae/10 m3). The success of northern pikeminnow in the Columbia River basin may be partly attributable to their ability to locate adequate spawning and rearing conditions in a variety of main-stem and tributary

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

    Directory of Open Access Journals (Sweden)

    Reynaldo Charrier

    2009-10-01

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

  11. PLIOCENE ALLUVIAL TO MARINE DEPOSITS OF THE VAL D’ORCIA BASIN (NORTHERN APENNINES, ITALY): SEQUENCE STRATIGRAPHY AND BASIN ANALYSIS

    OpenAIRE

    MASSIMILIANO GHINASSI

    2007-01-01

    Since the Middle-Late Miocene, the Apennine chain was characterised by the development of several basins. These basins have been alternatively explained as extensional post-orogenic basins or syn-orogenic compressional basins. In this framework, the Pliocene depositional history of the Val d'Orcia Basin (Southern Tuscany) is described, based on a sequence stratigraphic approach. Three depositional sequences (Vd3a-c) have been recognized. The Vd3a sequence records marine ingression and subsequ...

  12. Polyphase tectonic subsidence evolution of the Vienna Basin inferred from quantitative subsidence analysis of the northern and central parts

    Science.gov (United States)

    Lee, Eun Young; Wagreich, Michael

    2016-04-01

    The Vienna Basin is a tectonically complex Neogene basin situated at the Alpine-Carpathian transition. This study analyzes a detailed quantification of subsidence in the northern and central parts of the Vienna Basin to understand its tectonic subsidence evolution. About 200 wells were used to arrange stratigraphic setting, and wells reaching the pre-Neogene basement were analyzed for subsidence. To enhance the understanding of the regional subsidences, the wells were sorted into ten groups based on their position on major fault blocks. In the Early Miocene, subsidence was slow and along E-W to NE-SW trending axis, indicating the development of thrust-controlled piggyback basins. During the late Early Miocene data show abruptly increasing subsidence, making the initiation of the Vienna pull-apart basin system. From the Middle Miocene, the tectonic subsidence curves show regionally different patterns. The tectonic subsidence during the Middle Miocene varies laterally across the Vienna Basin, and the differential subsidence can be related to the changing tensional regime of weakening transtension and strengthening extension toward the late Middle Miocene. From the late Middle Miocene to the Late Miocene, the tectonic subsidence occurred dominantly along the regional active faults, and corresponds to the axis of E-W trending extension of the western parts of the Pannonian Basin system. In the Quaternary the Vienna Basin has been reactivated, and resulted in subsidence along the NE-SW trending Vienna Basin transfer fault system.

  13. The jurassic events in the Greater Caucasus basin (Northern Neotethys and the Neuquén basin (West Gondwana: a comparison

    Directory of Open Access Journals (Sweden)

    Dmitry A. Ruban

    2008-12-01

    Full Text Available Quite a few common tectonic, palaeoenvironmental, and palaeobiological events have been recognized in the Jurassic evolution of the Greater Caucasus basin (Northern Neotethys and the Neuquén basin (West Gondwana. Both basins were originated by the same planetary-scale tectonic force, i.e., by the activity of the Intrapangaean Shear Zone stretching eastwards along the Eurasian margin as the Northern Tethyan Shear Zone. An oxygen depletion occurred in both studied regions in the Toarcian as a result of global anoxia, which provoked a mass extinction. In both basins, the Callovian was a time for the carbonate platform growth, although in the Greater Caucasus, a carbonate platform appeared only in the Late Callovian. A salinity crisis occurred in the Greater Caucasus during the Kimmeridgian-Tithonian, whereas the same took place twice in the Neuquén basin - in the Middle Callovian and in the late Oxfordian-Kimmeridgian. These events were related to the global epoch of evaporite deposition. Some important differences between the considered basins are also documented. Palaeontological data from the Neuquén basin suggest against the mass extinction at the Jurassic-Cretaceous transition. In contrast, data from the Greater Caucasus basin permit to recognize this global event, although its regional peak occurred in the Berriasian. The Jurassic transgressions and regressions in the Greater Caucasus and western Argentina differed, facts that may be explained by the differences in the regional geodynamics. The only common pattern was a stepwise transgression during the Sinemurian-Pliensbachian.

  14. A Very Large Population of Likely Buried Impact Basins in the Northern Lowlands of Mars Revealed by MOLA Data

    Science.gov (United States)

    Frey, H. V.; Shockey, K. M.; Frey, E. L.; Roark, J. H.; Sakimoto, S. E. H.

    2001-01-01

    High resolution Mars Orbiter Laser Altimeter (MOLA) data have revealed a large number of subdued quasi-circular depressions (QCDs) >50 km diameter in the northern lowlands of Mars which are generally not visible in Viking imagery and which may be buried ancient impact basins. Additional information is contained in the original extended abstract.

  15. Facies-controlled volcanic reservoirs of northern Songliao Basin, NE China

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Volcanic rocks of the late Mesozoic are very important reservoirs for the commercial natural gases including hydrocarbon, carbon dioxide and rare gases in the northern Songliao Basin. The reservoir volcanic rocks include rhyolite,andesite, trachyte, basalt and tuff. Facies of the volcanic rocks can be classified into 5 categories and 15 special types.Porosity and permeability of the volcanic reservoirs are facies-controlled. Commercial reservoirs were commonly found among the following volcanic subfacies: volcanic neck (Ⅰ1), underground-explosive breccia (Ⅰ3), pyroclastic-bearing lava flow (Ⅱ3), upper effusive (Ⅲ3) and inner extrusive ones (Ⅳ1). The best volcanic reservoirs are generally evolved in the interbedded explosive and effusive volcanics. Rhyolites show in general better reservoir features than other types of rocks do.

  16. Hydrogeochemistry of high-fluoride groundwater at Yuncheng Basin, northern China.

    Science.gov (United States)

    Li, Chengcheng; Gao, Xubo; Wang, Yanxin

    2015-03-01

    Hydrogeochemical and environmental isotope methods were integrated to delineate the spatial distribution and enrichment of fluoride in groundwater at Yuncheng Basin in northern China. One hundred groundwater samples and 10 Quaternary sediment samples were collected from the Basin. Over 69% of the shallow groundwater (with a F(-) concentration of up to 14.1mg/L), 44% of groundwater samples from the intermediate and 31% from the deep aquifers had F(-) concentrations above the WHO provisional drinking water guideline of 1.5mg/L. Groundwater with high F(-) concentrations displayed a distinctive major ion chemistry: Na-rich and Ca-poor with a high pH value and high HCO3(-) content. Hydrochemical diagrams and profiles and hydrogen and oxygen isotope compositions indicate that variations in the major ion chemistry and pH are controlled by mineral dissolution, cation exchange and evaporation in the aquifer systems, which are important for F(-) mobilization as well. Leakage of shallow groundwater and/or evaporite (gypsum and mirabilite) dissolution may be the major sources for F(-) in groundwater of the intermediate and deep aquifers. PMID:25478652

  17. Arsenic release by indigenous bacteria Bacillus cereus from aquifer sediments at Datong Basin, northern China

    Science.gov (United States)

    Xie, Zuoming; Wang, Yanxin; Duan, Mengyu; Xie, Xianjun; Su, Chunli

    2011-03-01

    Endemic arsenic poisoning due to long-term drinking of high arsenic groundwater has been reported in Datong Basin, northern China. To investigate the effects of microbial activities on arsenic mobilization in contaminated aquifers, Bacillus cereus ( B. cereus) isolated from high arsenic aquifer sediments of the basin was used in our microcosm experiments. The arsenic concentration in the treatment with both bacteria and sodium citrate or glucose had a rapid increase in the first 18 d, and then, it declined. Supplemented with bacteria only, the concentration could increase on the second day. By contrast, the arsenic concentration in the treatment supplemented with sodium citrate or glucose was kept very low. These results indicate that bacterial activities promoted the release of arsenic in the sediments. Bacterial activities also influenced other geochemical parameters of the aqueous phase, such as pH, Eh, and the concentrations of dissolved Fe, Mn, and Al that are important controls on arsenic release. The removal of Fe, Mn, and Al from sediment samples was observed with the presence of B. cereus. The effects of microbial activities on Fe, Mn, and Al release were nearly the same as those on As mobilization. The pH values of the treatments inoculated with bacteria were lower than those without bacteria, still at alkaline levels. With the decrease of Eh values in treatments inoculated with bacteria, the microcosms became more reducing and are thus favorable for arsenic release.

  18. Using Diverse Data Types to Calibrate a Watershed Model of the Trout Lake Basin, Northern Wisconsin

    Science.gov (United States)

    Hunt, R. J.; Feinstein, D. T.; Pint, C. D.; Anderson, M. P.

    2004-12-01

    As part of the USGS Water, Energy, and Biogeochemical Budgets project and NSF Long-Term Ecological Research work, a parameter estimation code was used to calibrate a deterministic groundwater flow model of the Trout Lake Basin in northern Wisconsin. Observations included traditional calibration targets (head, lake stage, and baseflow observations) as well as unconventional targets such as groundwater flows to and from lakes, depth of a lake plume, and time of travel. The unconventional data types were important for parameter estimation convergence and allowed the development of a more parameterized model. Independent estimates of groundwater inflow to lakes were most important for constraining lakebed leakance, and the depth of the lake plume was important for determining hydraulic conductivity and conceptual aquifer layering. The most important target, however, was a conventional regional baseflow target that was important for correctly distributing flow between sub-basins and the regional system. The use of parameter estimation: 1) facilitated the calibration process by providing a quantitative assessment of the model's ability to match disparate observed data types; and 2) provided a best fit for the particular model conceptualization. The model calibration required the use of a "universal" parameter estimation code in order to include all types of observations in the objective function. The methods described here help address issues of watershed complexity and non-uniqueness common to deterministic watershed models.

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

    Directory of Open Access Journals (Sweden)

    KAREN FLORES

    2009-03-01

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

  20. Land cover changes associated with recent energy development in the Williston Basin; Northern Great Plains, USA.

    Science.gov (United States)

    Preston, Todd M; Kim, Kevin

    2016-10-01

    The Williston Basin in the Northern Great Plains has experienced rapid energy development since 2000. To evaluate the land cover changes resulting from recent (2000-2015) development, the area and previous land cover of all well pads (pads) constructed during this time were determined, the amount of disturbed and reclaimed land adjacent to pads was estimated, land cover changes were analyzed over time for three different well types, and the effects from future development were predicted. The previous land cover of the 12,990ha converted to pads was predominately agricultural (49.5%) or prairie (47.4%) with lesser amounts of developed (2.3%), aquatic (0.5%), and forest (0.4%). Additionally, 12,121ha has likely been disturbed and reclaimed. The area required per gas well remained constant through time while the land required per oil well increased initially and then decreased as development first shifted from conventional to unconventional drilling and then to multi-bore pads. For non-oil-and-gas wells (i.e. stratigraphic test wells, water wells, and injection wells), the area per well increased through time likely due to increased produced water disposal requirements. Future land cover change is expected to be 2.7 times greater than recent development with much of the development occurring in five counties in the core Bakken development area. Direct land cover change and disturbance from recent and expected development are predicted to affect 0.4% of the landscape across the basin; however, in the core Bakken development area, 2.3% of the landscape will be affected including 2.1% of the remaining grassland. Although future development will result in significant land cover change, evolving industry practices and proactive siting decisions, such as development along energy corridors and placing pads in areas previously altered by human activity, have the potential to reduce the ecological effects of future energy development in the Williston Basin. PMID:27318516

  1. Source identification of fine-grained suspended sediment in the Kharaa River basin, northern Mongolia

    International Nuclear Information System (INIS)

    Fine sediment inputs into river systems can be a major source of nutrients and heavy metals and have a strong impact on water quality and ecosystem functions of rivers and lakes, including those in semiarid regions. However, little is known to date about the spatial distribution of sediment sources in most large scale river basins in Central Asia. Accordingly, a sediment source fingerprinting technique was used to assess the spatial sources of fine-grained (< 10 μm) sediment in the 15 000 km2 Kharaa River basin in northern Mongolia. Variation in geochemical composition (e.g. in Ti, Sn, Mo, Mn, As, Sr, B, U, Ca and Sb) was used for sediment source discrimination with geochemical composite fingerprints based on Genetic Algorithm (GA)-driven Discriminant Function Analysis, the Kruskal–Wallis H-test and Principal Component Analysis. All composite fingerprints yielded a satisfactory GOF (> 0.97) and were subsequently used for numerical mass balance modelling with uncertainty analysis. The contributions of the individual sub-catchment spatial sediment sources varied from 6.4% (the headwater sub-catchment of Sugnugur Gol) to 36.2% (the Kharaa II sub-catchment in the middle reaches of the study basin), generally showing higher contributions from the sub-catchments in the middle, rather than the upstream, portions of the study area. The importance of river bank erosion is shown to increase from upstream to midstream tributaries. The source tracing procedure provides results in reasonable accordance with previous findings in the study region and demonstrates the applicability and associated uncertainties of the approach for fine-grained sediment source investigation in large scale semi-arid catchments. - Highlights: • Applied statistical approach for selecting composite fingerprints in Mongolia. • Geochemical fingerprinting for the definition of source areas in semiarid catchment. • Test of applicability of sediment sourcing in large scale semi-arid catchments.

  2. Source identification of fine-grained suspended sediment in the Kharaa River basin, northern Mongolia

    Energy Technology Data Exchange (ETDEWEB)

    Theuring, Philipp [Department of Aquatic Ecosystem Analysis and Management — ASAM, Helmholtz Centre for Environmental Research — UFZ, Brückstrasse 3a, D-39114 Magdeburg (Germany); Collins, Adrian L. [Sustainable Soils and Grassland Systems Department, Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB (United Kingdom); Rode, Michael [Department of Aquatic Ecosystem Analysis and Management — ASAM, Helmholtz Centre for Environmental Research — UFZ, Brückstrasse 3a, D-39114 Magdeburg (Germany)

    2015-09-01

    Fine sediment inputs into river systems can be a major source of nutrients and heavy metals and have a strong impact on water quality and ecosystem functions of rivers and lakes, including those in semiarid regions. However, little is known to date about the spatial distribution of sediment sources in most large scale river basins in Central Asia. Accordingly, a sediment source fingerprinting technique was used to assess the spatial sources of fine-grained (< 10 μm) sediment in the 15 000 km{sup 2} Kharaa River basin in northern Mongolia. Variation in geochemical composition (e.g. in Ti, Sn, Mo, Mn, As, Sr, B, U, Ca and Sb) was used for sediment source discrimination with geochemical composite fingerprints based on Genetic Algorithm (GA)-driven Discriminant Function Analysis, the Kruskal–Wallis H-test and Principal Component Analysis. All composite fingerprints yielded a satisfactory GOF (> 0.97) and were subsequently used for numerical mass balance modelling with uncertainty analysis. The contributions of the individual sub-catchment spatial sediment sources varied from 6.4% (the headwater sub-catchment of Sugnugur Gol) to 36.2% (the Kharaa II sub-catchment in the middle reaches of the study basin), generally showing higher contributions from the sub-catchments in the middle, rather than the upstream, portions of the study area. The importance of river bank erosion is shown to increase from upstream to midstream tributaries. The source tracing procedure provides results in reasonable accordance with previous findings in the study region and demonstrates the applicability and associated uncertainties of the approach for fine-grained sediment source investigation in large scale semi-arid catchments. - Highlights: • Applied statistical approach for selecting composite fingerprints in Mongolia. • Geochemical fingerprinting for the definition of source areas in semiarid catchment. • Test of applicability of sediment sourcing in large scale semi-arid catchments

  3. Crustal structure beneath the Northern Transantarctic Mountains and Wilkes Subglacial Basin: Implications for tectonic origins

    Science.gov (United States)

    Hansen, Samantha E.; Kenyon, Lindsey M.; Graw, Jordan H.; Park, Yongcheol; Nyblade, Andrew A.

    2016-02-01

    The Transantarctic Mountains (TAMs) are the largest noncollisional mountain range on Earth. Their origin, as well as the origin of the Wilkes Subglacial Basin (WSB) along the inland side of the TAMs, has been widely debated, and a key constraint to distinguish between competing models is the underlying crustal structure. Previous investigations have examined this structure but have primarily focused on a small region of the central TAMs near Ross Island, providing little along-strike constraint. In this study, we use data from the new Transantarctic Mountains Northern Network and from five stations operated by the Korea Polar Research Institute to investigate the crustal structure beneath a previously unexplored portion of the TAMs. Using S wave receiver functions and Rayleigh wave phase velocities, crustal thickness and average crustal shear velocity (V>¯s) are resolved within ±4 km and ±0.1 km/s, respectively. The crust thickens from ~20 km near the Ross Sea coast to ~46 km beneath the northern TAMs, which is somewhat thicker than that imaged in previous studies beneath the central TAMs. The crust thins to ~41 km beneath the WSB. V>¯s ranges from ~3.1-3.9 km/s, with slower velocities near the coast. Our findings are consistent with a flexural origin for the TAMs and WSB, where these features result from broad flexure of the East Antarctic lithosphere and uplift along its western edge due to thermal conduction from hotter mantle beneath West Antarctica. Locally, thicker crust may explain the ~1 km of additional topography in the northern TAMs compared to the central TAMs.

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

    Science.gov (United States)

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

    1989-01-01

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

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

    Science.gov (United States)

    Salinas, Carla; Mendieta, Jon

    2014-05-01

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

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

    OpenAIRE

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

    2006-01-01

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

  7. Hydrothermal recrystallization of the Lower Ordovician dolomite and its significance to reservoir in northern Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Discovered in S15 and some other wells, the Lower Ordovician in the northern Tarim Basin consists mainly of brown gray-dark gray very fine-fine crystalline dolomite, with a minor portion of locally light gray-white medium-coarse crystalline dolomite. Silicification can be observed in the medium-coarse dolomite, and some euhedral drusy quartz can also be found in pores and fractures of the dolomite. The homogenization temperature of the fluid inclusions in the medium-coarse dolomite is between 110 and 200°C with maximum between 140 and 190°C, and the salinity is between 10.7 and 18.5 wt.% NaCl Eq. The homogenization temperature and salinity of the fluid inclusions in the medium-coarse dolomite are similar to those in the drusy quartz. Compared with the very fine-fine dolomite, the medium-coarse phase contains relatively high Fe and Mn. The average concentration of FeO and MnO in the medium-coarse dolomite is 1.917% and 0.323%, respectively. The medium-coarse dolomite has a remarkable negative Eu anomaly, consistent with the REE pattern of the intermediate-felsic igneous rocks in the Tarim Basin. The oxygen isotopic composition of the medium-coarse dolomite is relatively lighter than that of the very fine-fine dolomite. The δ18OPDB values of the medium-coarse dolomite are between -10.35‰ and -7.31‰. The δ18OSMOW values of the fluid associated with the medium-coarse dolomite can be calculated according to homogenization temperature and oxygen isotope fractionation factor between dolomite and fluid, and the calculated values are between +4‰ and +10‰, consistent with those of the hydrothermal fluid. The medium-coarse dolomite has relatively high 87Sr/86Sr ratios as well, indi- cating an origin associated with intermediate-felsic igneous rock. The homogenization temperature, element composition, REE pattern, oxygen and strontium isotopes demonstrate that the medium-coarse dolomite is the result of recrystallization of very fine-fine dolomite under

  8. Low palaeoelevation of the northern Lhasa terrane during late Eocene: Fossil foraminifera and stable isotope evidence from the Gerze Basin

    Science.gov (United States)

    Wei, Yi; Zhang, Kexin; Garzione, Carmala N.; Xu, Yadong; Song, Bowen; Ji, Junliang

    2016-01-01

    The Lhasa terrane is a key region for understanding the paleoelevation of the southern Tibetan Plateau after India-Asia collision. The Gerze Basin, located in the northern part of the Lhasa terrane, is a shortening-related basin. We discovered Lagena laevis (Bandy) fossils in upper Eocene strata of the Gerze Basin. This type of foraminifera is associated with lagoon and estuarine environments, indicating that the northern part of the Lhasa terrane was near sea level during the late Eocene. We speculate that these foraminifera were transported inland by storm surges to low elevation freshwater lakes during times of marine transgressions. This inference is consistent with the relatively positive δ18O values in carbonate from the same deposits that indicate low palaeoelevations close to sea level. Considering the palaeoelevation results from the nearby Oligocene basins at a similar latitude and the volcanic history of the Lhasa terrane, we infer that large-magnitude surface uplift of the northern Lhasa terrane occurred between late Eocene and late Oligocene time. PMID:27272610

  9. Radionuclide levels in fish from Lake Athabasca February 1993. Northern River Basins Study project report no.26

    International Nuclear Information System (INIS)

    The Northern River Basins Study was initiated through the 'Canada-Alberta-Northwest Territories Agreement Respecting the Peace-Athabasca-Slave River Basin Study, Phase II - Technical Studies' which was signed September 27, 1991. The purpose of the study is to understand and characterize the cumulative effects of development on the water and aquatic environment of the Study Area by coordinating with existing programs and undertaking appropriate new technical studies. This publication reports the method and findings of particular work conducted as part of the Northern River Basins Study. As such, the work was governed by a specific terms of reference and is expected to contribute information about the Study Area within the context of the overall study as described by the Study Final Report. This report has been reviewed by the Study Science Advisory Committee in regards to scientific content and has been approved by the Study Board of Directors for public release. It is explicit in the objectives of the Study to report the results of technical work regularly to the public. This objective is served by distributing project reports to an extensive network of libraries, agencies, organizations and interested individuals and by granting universal permission to reproduce the material. This report contains referenced data obtained from external to the Northern River Basins Study. Individuals interested in using external data must obtain permission to do so from the donor agency. (author). 47 refs., 9 tabs., 2 figs

  10. Seismic sequence and depositional evolution of slope basins in mid-northern margin of the South China Sea

    Institute of Scientific and Technical Information of China (English)

    LI Mingbi; JIN Xianglong; LI Jiabiao; DING Weiwei; FANG Yinxia; LIU Jianhua; TANG Yong

    2011-01-01

    As one of the biggest marginal seas in the western Pacific margin,the South China Sea (SCS) experienced continental riffing and seafloor spreading during the Cenozoic.The northern continental margin of the SCS is classified as a passive continental margin.However,its depositional and structural evolution remains controversial,especially in the deep slope area.The lack of data hindered the correlation between continental shelf and oceanic basin,and prevented the establishment of sequence stratigraphic frame of the whole margin.The slope basins in the mid-northern margin of SCS developed in the Cenozoic;the sediments and basin infill recorded the geological history of the continental margin and the SCS spreading.Using multi-channel seismic dataset acquired in three survey cruises during 1987 to 2004,combined with the data of ODP Leg 184 core and industrial wells,we carried out the sequence stratigraphic division and correlation of the Cenozoic in the middle-northern margin of SCS with seismic profiles and sedimentary facies.We interpreted the seismic reflection properties including continuity,amplitude,frequency,reflection terminals,and 15 sequence boundaries of the Cenozoic in the study area,and correlated the well data in geological age.The depositional environment changed from river and lake,shallow bay to open-deep sea,in correspondence to tectonic events of syn-rifting,early drifting,and late drifting stages of basin evolution.

  11. Low palaeoelevation of the northern Lhasa terrane during late Eocene: Fossil foraminifera and stable isotope evidence from the Gerze Basin

    Science.gov (United States)

    Wei, Yi; Zhang, Kexin; Garzione, Carmala N.; Xu, Yadong; Song, Bowen; Ji, Junliang

    2016-06-01

    The Lhasa terrane is a key region for understanding the paleoelevation of the southern Tibetan Plateau after India-Asia collision. The Gerze Basin, located in the northern part of the Lhasa terrane, is a shortening-related basin. We discovered Lagena laevis (Bandy) fossils in upper Eocene strata of the Gerze Basin. This type of foraminifera is associated with lagoon and estuarine environments, indicating that the northern part of the Lhasa terrane was near sea level during the late Eocene. We speculate that these foraminifera were transported inland by storm surges to low elevation freshwater lakes during times of marine transgressions. This inference is consistent with the relatively positive δ18O values in carbonate from the same deposits that indicate low palaeoelevations close to sea level. Considering the palaeoelevation results from the nearby Oligocene basins at a similar latitude and the volcanic history of the Lhasa terrane, we infer that large-magnitude surface uplift of the northern Lhasa terrane occurred between late Eocene and late Oligocene time.

  12. 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.

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

    Directory of Open Access Journals (Sweden)

    Alejandro Abarca

    2012-09-01

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

  14. New seismo-stratigraphic data of the Volturno Basin (northern Campania, Tyrrhenian margin, southern Italy: implications for tectono-stratigraphy of the Campania and Latium sedimentary basins

    Directory of Open Access Journals (Sweden)

    Ennio Marsella

    2011-07-01

    Full Text Available A geological section of the Volturno Basin (northern Campania, continental margin, Italy has been constructed based on new multi-channel seismic data, to show the stratigraphic relationships between the filling in the Quaternary basin and the Meso-Cenozoic acoustic basement. The new seismic sections presented here outline the underlying structures of the basin and their relationships to the filling in the Quaternary basin. Deep exploration wells in Campania and Latium on the Tyrrhenian margin have gathered litho-stratigraphic and commercial multi-channel seismic data that can be used for better integration of the geological data for the area under study. The trending of the seismic units is controlled by the Massico Structural High, which forms the boundary of the Volturno Basin towards the north-west. This produces a geometry that is characteristic of a fan complex, with NE-SW trending. This qualitative calibration of the seismic sequences that fill the sedimentary basin was carried out through the litho-stratigraphic data of the «Castelvolturno 2» well, which highlights the pyroclastic layers and conglomeratic strata of the lagoon and delta environments as they evolve upwards towards marine sediments. Seismo-stratigraphic analysis shows the complex depositional geometries of the filling in the Volturno Basin, which overlie the Meso-Cenozoic carbonatic basement and the related flysch deposits. Coupled with regional geological evidence, the data interpretation here suggests that the Volturno Basin represents a half-graben structure that is characterized by down-thrown blocks along normal faults.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-08-15

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

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

    Science.gov (United States)

    Krewcun, Lucie G.

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

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

    Science.gov (United States)

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

    2016-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-31

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

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

    Science.gov (United States)

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

    2015-08-01

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

  20. ITCZ-monsoonal association during the last glacial (Cariaco Basin, Northern Arabian Sea)

    Science.gov (United States)

    Deplazes, G.; Haug, G. H.; Lueckge, A.

    2010-12-01

    The anoxic Cariaco Basin on the northern shelf of Venezuela preserves detailed records of past tropical climate variability. The sediment formation in this basin is controlled by the migration of the Atlantic Intertropical Convergence Zone (ITCZ) and the corresponding rain belt and trade winds. In the oxygen minimum zone off Pakistan in the northeastern Arabian Sea sediment archives of low-latitude monsoonal climate are preserved. In this study sediments from the two settings that cover the last 80,- to 110,000 years were analysed. Sediment color analysis resulted in reflectance records with a down to annual resolution. An age model was set up by correlation of these records to the δ18O record of Greenland ice (NGRIP). The major element chemistry of the sediments was analysed with X-ray fluorescence scanning. The new high resolution proxy records indicate an unbroken association between warm climate conditions over Greenland, a northerly position of the Atlantic Intertropical Convergence Zone, and a strong Indian summer monsoon since the last glacial. The tight coupling is explained by a dominant role of the North Atlantic that is communicated largely through the atmosphere. New insights of dynamical mechanisms arise from comparison of individual Dansgaard-Oeschger events. The tropical records and the Greenland δ18O record show both an abrupt change at the beginning of an interstadial. The δ18O of Greenland ice peaks early in the interstadials and then decreases more or less constantly toward stadial values. However, the tropical records have a tendency to maintain dark interstadial color on a similar level over several centuries. The following centennial-scale lightening toward the next stadial appears to be delayed compared to the δ18O ice record. This “resistance” of the tropics to the interstadial-stadial transitions suggests a threshold response of the tropics to North Atlantic cooling.

  1. Development of Overpressure in the Tertiary Damintun Depression, Liaohe Basin, Northern China

    Institute of Scientific and Technical Information of China (English)

    YE Jiaren; HAO Fang; CHEN Jianyu

    2003-01-01

    The Damintun depression is one of the four depressions in the Liaohe basin in northern China, and is a rift basin developed in the Paleogene. This paper discusses in detail the characteristics of pressure and fluid potential of the Damintun depression based on a synthesis of the data from boreholes, well tests and seismic surveys. Data from sonic logs, well tests and seismic velocity measurements are used to study the pressure characteristics of the areas. From the sonic log data, shales can be characterized as normally pressured, slightly overpressured or highly overpressured; from the well test data, the pressure-depth gradient in oil-producing intervals implies hydrostatic pressure in general. Most seismic profiles in the Damintun depression are of sufficiently high quality for seismic velocities to be measured. The fluid pressures, excess pressures and pressure coefficients in 47 representative seismic profiles are predicted using formula calculation methods, and further transformed to fluid potentials. The resultant pressure profiles show normal pressure, moderate overpressure and intense overpressure increasing with depth. The pressure evolution can be divided into three stages as initial generation, partial dissipation and re-accumulation. Fluid potential is the principal factor controlling hydrocarbon migration in a reservoir. Its distribution varies with depth; above the T4 interface a gravity-flow dominates, whereas beneath it a compaction flow dominates. The development of overpressure in the Damintun depression has a crucial influence on the distribution of fluid potentials, which agrees with that of overpressure in general. The results of the fluid potential analysis indicate that the areas of Dongshenpu-Xinglongpu and the southwestern part of the depression are most favorable for hydrocarbon migration and accumulation.

  2. Blastocistosis y otras infecciones por protozoos intetinales en comunidades humanas ribereñas de la cuenca del rio Valdivia, Chile Blastocystosis and other intestinal protozoan infections in human riverside communities from - Valdivia River Basin, Chile

    Directory of Open Access Journals (Sweden)

    Patricio Torres

    1992-12-01

    Full Text Available Entre marzo y octubre de 1987 se examinaron muestras coprológicas de 970 personas (20, 9% de la población pertenecientes a 209 grupos familiares de las comunidades ribereñas de la cuenca del rio Valdivia, Chile; con el propósito de determinar las prevalencias de infección por Blastocystis hominis y otros protozoos intestinales para establecer relaciones con la edad y sexo de los hospedadores, saneamiento ambiental y porcentaje de individuos infectados por grupo familiar. Un 72, 5% de las personas presentó una o más especies de protozoos intestinales. La mayor prevalencia se registró para B. hominis (61, 8%, que se incrementó con la edad del hospedador al igual que en las infecciones por Endolimax nana y Entamoeba coli. No se demostró asociación entre el sexo del hospedador y la prevalencia de infección por B. hominis y otras especies de protozoos. La prevalencia de B. hominis fue mayor en individuos que habitaban viviendas cuya disposition de excrementos era no sanitaria. Más del 60% de los integrantes de los grupos familiares presentaron infección por B. hominis en el 53, 1% de las familias encuestadas en contraposición al 2,4%-21,8% observado en infecciones por otros protozoos. El examen de 45 muestras de excrementos de cerdos, reveló infección por Blastocystis en el 22,2% de estos animales.Between March and October 1987, the prevalence of infection by Blastocystis hominis and other intestinal protozoan, their relationship with the age and sex of the hosts, and the percentage of in fected persons in family groups were determined in riverside communities of Valdivia River Basin, Chile. One or more intestinal protozoan species were determined in 72.5% of the examined persons. The prevalence was greater for B. hominis (61.8%. The prevalences of B. hominis, Endolimax nana and Entamoeba coli were greater in relation to the age of the host. The sex of the host and prevalence of infections by B. hominis and other species of

  3. Effects of precipitation and potential evaporation on actual evapotranspiration over the Laohahe basin, northern China

    Science.gov (United States)

    Liu, Y.; Ren, L.; Yang, X.; Ma, M.; Yuan, F.; Jiang, S.

    2015-06-01

    Problems associated with water scarcity are facing new challenges under the climate change. As one of main consumptions in water cycle on the Earth, evapotranspiration plays a crucial role in regional water budget. In this paper, we employ two methods, i.e. hydrological sensitivity analysis and hydrological model simulation, to investigate the effect of climate variability and climatic change on actual evapotranspiration (Ea) within the Laohahe basin during 1964-2009. Calibrations of the two methods are firstly conducted during the baseline period (1964-1979), then with the two benchmarked models, simulations in climatic change duration (1980-2009) are further conducted and quantitative assessments on climatic change-induced variation of Ea are analysed accordingly. The results show that affected by combined impacts of decreased precipitation and potential evapotranspiration, variation of annual Ea in most sub-catchments suffer a downward trend during 1980-2009, with a higher descending rate in northern catchments. At decadal scale, Ea shows significant oscillation in accordance with precipitation patterns. Northern catchments generally suffer more decadal Ea changes than southern catchments, implying the impact of climatic change on decadal Ea is more intense in semi-arid areas than that in semi-humid regions. For whole changed durations, a general 0-20 mm reduction of Ea is found in most parts of studied region. For this water-limited region, Ea shows higher sensitivity to precipitation than to potential evaporation, which confirms the significant role of precipitation in controlling Ea patterns, whereas the impact of potential evapotranspiration variation would be negligible.

  4. High resolution sequence stratigraphic analysis of the Late Miocene Abu Madi Formation, Northern Nile Delta Basin

    Science.gov (United States)

    Sarhan, Mohammad Abdelfattah

    2015-12-01

    Abu Madi Formation represents the Upper Miocene Messinian age in the Nile Delta basin. It consists mainly of sandstones and shale intercalations and because of its richness in hydrocarbon, it has been subdivided by the petroleum companies into Level-I, Level-II and Level-III, respectively according to the increase in the sandstone to the shale ratio. The Miocene cycle in the northern subsurface section of the Nile Delta encompasses three main formations namely from the base; Sidi Salim formation, Qawasim Formation and Abu Madi Formation at the top. The high resolution sequence stratigraphic analysis, using gamma ray responses, has been done for the Late Miocene formation in the northern part of the Nile delta subsurface section. For this purpose, the gamma-ray logs of ten deep wells, arranged in four cross-sections trending in almost north-south direction throughout the northern region of the Nile Delta, were analyzed. The analysis has revealed that the interpreted 4th order depositional cycles within Abu Madi Formation display great variations in both number and gamma ray responses in each investigated well, and cannot be traced laterally, even in the nearest well. These variations in the interpreted 4th order depositional sequences could be attributed to the presence of normal faults buried in the inter-area laying between the investigated wells. This finding matches with the conclusion of that Abu Madi Formation represents a part of the Upper Miocene Nile Delta syn-rift megasequence, developed during the Upper Miocene rift phase of the Red Sea - Gulf of Suez province in Egypt. Accordingly, in the sequence stratigraphic approach, the depositional history of Abu Madi Formation was strongly overprinted by the tectonic controls rather than the relative sea-level changes which are assumed to be of a secondary influence. Regarding the hydrocarbon aspects of the Abu Madi Formation, the present work recommends to direct the drilling efforts into the stratigraphic traps

  5. Closed basin brine evolution and the influence of Ca-Cl inflow waters : Death Valley and Bristol Dry Lake California, Qaidam Basin, China, and Salar de Atacama, Chile

    OpenAIRE

    Lowenstein, T. K.; Risacher, François

    2009-01-01

    Diagenetic-hydrothermal brines, here called "hydrothermal Ca-Cl brines," have compositions that reflect interactions between groundwaters and rocks or sediments at elevated temperatures. Hydrothermal Ca-Cl brines reach the surface by convection-driven or topographically driven circulation, and discharge as springs or seeps along fault zones to become important inflow waters in many tectonically active closed basins. Case studies from (1) Qaidam Basin, China, (2) Death Valley, California, (3) ...

  6. Peat accumulation in drained thermokarst lake basins in continuous, ice-rich permafrost, northern Seward Peninsula, Alaska

    Science.gov (United States)

    Jones, Miriam C.; Grosse, Guido; Jones, Benjamin M.; Anthony, Katey Walter

    2012-01-01

    Thermokarst lakes and peat-accumulating drained lake basins cover a substantial portion of Arctic lowland landscapes, yet the role of thermokarst lake drainage and ensuing peat formation in landscape-scale carbon (C) budgets remains understudied. Here we use measurements of terrestrial peat thickness, bulk density, organic matter content, and basal radiocarbon age from permafrost cores, soil pits, and exposures in vegetated, drained lake basins to characterize regional lake drainage chronology, C accumulation rates, and the role of thermokarst-lake cycling in carbon dynamics throughout the Holocene on the northern Seward Peninsula, Alaska. Most detectable lake drainage events occurred within the last 4,000 years with the highest drainage frequency during the medieval climate anomaly. Peat accumulation rates were highest in young (50–500 years) drained lake basins (35.2 g C m−2 yr−1) and decreased exponentially with time since drainage to 9 g C m−2 yr−1 in the oldest basins. Spatial analyses of terrestrial peat depth, basal peat radiocarbon ages, basin geomorphology, and satellite-derived land surface properties (Normalized Difference Vegetation Index (NDVI); Minimum Noise Fraction (MNF)) from Landsat satellite data revealed significant relationships between peat thickness and mean basin NDVI or MNF. By upscaling observed relationships, we infer that drained thermokarst lake basins, covering 391 km2 (76%) of the 515 km2 study region, store 6.4–6.6 Tg organic C in drained lake basin terrestrial peat. Peat accumulation in drained lake basins likely serves to offset greenhouse gas release from thermokarst-impacted landscapes and should be incorporated in landscape-scale C budgets.

  7. Determination of faults parameters controlling the Petroleum Systems Elements in the northern North Sea by using 3D basin Modelling

    OpenAIRE

    Andriamihaja, Spariharijaona

    2011-01-01

    3D basin modelling of the northern North Sea region covering 4886km2 is performed in order to understand the petroleum system elements within the area. The approach used to obtain the most likely model is to analyze and determine quantitatively the faults properties controlling the hydrocarbons accumulations in the Gullfaks, Visund, Kvitebjørn, and Huldra fields. This approach is made by varying the faults properties defined by shale gauge ratio until the reserves in place in the four fields ...

  8. Growth Normal Faulting at the Western Edge of the Metropolitan Taipei Basin since the Last Glacial Maximum, Northern Taiwan

    OpenAIRE

    Chih-Tung Chen; Jian-Cheng Lee; Yu-Chang Chan; and Chia-Yu Lu

    2010-01-01

    Growth strata analysis is an useful tool in understanding kinematics and the evolution of active faults as well as the close relationship between sedimentation and tectonics. Here we present the Shanchiao Fault as a case study which is an active normal fault responsible for the formation of the 700-m-thick late Quaternary deposits in Taipei Basin at the northern tip of the Taiwan mountain belt. We compiled a sedimentary record, particularly the depositional facies and their dated ages, at thr...

  9. Analysis of geological characteristics of uranium mineralization of Na Linggou in Husiliang located in the northern of Ordos basin

    International Nuclear Information System (INIS)

    In this paper, rock facies, the development of interlayer oxidation zone and the control factors and characteristics of uranium mineralization in northern Ordos basin in terms of beam areas call Adams Ridge sulcus satisfied lots Zhiluo uranium mineralization characteristics do lower concluded that the location uranium mineralization controlled by the interlayer oxidation zone of uranium deposits located in the developed parts of the faults. (author)

  10. Trace fossils associated to the end-Messinian unconformity in the northern border of the Bajo Segura Basin (SE Spain)

    OpenAIRE

    Caracuel, Jesús Esteban; Corbí, Hugo; Estévez, Antonio; Giannetti, Alice; Monaco, Paolo; Pina, José Antonio; Soria, Jesús M.; Tent Manclús, José Enrique; Yébenes, Alfonso

    2009-01-01

    A detailed analysis of the Upper Messinian-Lower Pliocene at the northern border of the Bajo Segura Basin (BSB) has been carried out. Trace fossils of firm- and rockground were collected, aiding in the recognition of three ichnofacies: Glossifungites (types A and B), Entobia and Gnathichnus. The ichnological data provide evidence that the Pliocene flooding of the BSB, after the Messinian Salinity Crisis, was developed in two pulses. In the first one, the ingression penetrated only along the p...

  11. PLIOCENE ALLUVIAL TO MARINE DEPOSITS OF THE VAL D’ORCIA BASIN (NORTHERN APENNINES, ITALY: SEQUENCE STRATIGRAPHY AND BASIN ANALYSIS

    Directory of Open Access Journals (Sweden)

    MASSIMILIANO GHINASSI

    2007-11-01

    Full Text Available Since the Middle-Late Miocene, the Apennine chain was characterised by the development of several basins. These basins have been alternatively explained as extensional post-orogenic basins or syn-orogenic compressional basins. In this framework, the Pliocene depositional history of the Val d'Orcia Basin (Southern Tuscany is described, based on a sequence stratigraphic approach. Three depositional sequences (Vd3a-c have been recognized. The Vd3a sequence records marine ingression and subsequent relative sea-level highstand in a narrow W-E trending depression. Subsequent relative sea-level fluctuations led to a progressive basin widening and deposition of Vd3b and Vd3c sequences. Basin scale sedimentation was mainly controlled by relative sea-level changes, although accumulation of bioclastic deposits of the Vd3c sequence could have been influenced by climatic factors. Based on its wide bowl-shaped geometry, the Pliocene Val d'Orcia Basin has been interpreted as an inherited depression. This depression is thought to be originated by erosion at the Late Miocene-Early Pliocene transition. 

  12. Calculated Porosity of Volcanic Reservoir in Wangjiatun of the Northern Songliao Basin, NE China

    Institute of Scientific and Technical Information of China (English)

    Xuanlong Shan; Chuanbiao Wa; Rihui Cheng; Wanzhu Liu

    2003-01-01

    In Wangjiatun area of the Northern Songliao Basin, reservoir space can be divided into three types: primary pore, secondary pore and fissure according to their origins,which can be subdivided into eight subtypes: macro-vesicule,shrank primary vesicule, alteration pore, groundmass corrosive pore, normal structural crack, corrosive structural crack,filled structural crack and groundmass shrank crack according to texture and origin of the pore space. It has characteristic of double pore medium. Volcanic porosities of small diameter samples (with diameter of ca. 2.5 cm) and large diameter samples (with diameter of ca. 21.5 cm) were tested in accordance with the characteristic of volcanic reservoir space. Volcanic porosities for small diameter samples correspond with matrix porosities and those of large diameter samples correspond with total porosities including matrix and fractured porosities. Models of the calculated porosity by acoustic wave or density of volcanic reservoir are established in view of those measured data. Comparison of calculated and measuredporosities shows that precision of calculated porosities is lower for rhyolite and tuffites, and higher for basaltand andesite.Relative errors of calculated porosities by model of large diameter samples are lower than those of small diameter samples, i. e. precision of the former is higher than that of the later.

  13. Cross-fault pressure depletion, Zechstein carbonate reservoir, Weser-Ems area, Northern German Gas Basin

    Energy Technology Data Exchange (ETDEWEB)

    Corona, F.V.; Brauckmann, F.; Beckmann, H.; Gobi, A.; Grassmann, S.; Neble, J.; Roettgen, K. [ExxonMobil Production Deutschland GmbH (EMPG), Hannover (Germany)

    2013-08-01

    A cross-fault pressure depletion study in Upper Permian Zechstein Ca2 carbonate reservoir was undertaken in the Weser-Ems area of the Northern German Gas Basin. The primary objectives are to develop a practical workflow to define cross-fault pressures scenarios for Zechstein Ca2 reservoir drillwells, to determine the key factors of cross-fault pressure behavior in this platform carbonate reservoir, and to translate the observed cross-fault pressure depletion to fault transmissibility for reservoir simulation models. Analysis of Zechstein Ca2 cross-fault pressures indicates that most Zechstein-cutting faults appear to act as fluid-flow baffles with some local occurrences of fault seal. Moreover, there appears to be distinct cross-fault baffling or pressure depletion trends that may be related to the extent of the separating fault or fault system, degree of reservoir flow-path tortuosity, and quality of reservoir juxtaposition. Based on the above observations, a three-part workflow was developed consisting of (1) careful interpretation and mapping of faults and fault networks, (2) analysis of reservoir juxtaposition and reservoir juxtaposition quality, and (3) application of the observed cross-fault pressure depletion trends. This approach is field-analog based, is practical, and is being used currently to provide reliable and supportable pressure prediction scenarios for subsequent Zechstein fault-bounded drill-well opportunities.

  14. Biostratigraphy, sedimentology and paleoenvironments of the northern Danube Basin: Ratkovce 1 well case study

    Directory of Open Access Journals (Sweden)

    Rybár Samuel

    2015-02-01

    Full Text Available The Ratkovce 1 well, drilled in the Blatné depocenter of the northern Danube Basin penetrated the Miocene sedimentary record with a total thickness of 2000 m. Biostratigraphically, the NN4, NN5 and NN6 Zones of calcareous nannoplankton were documented; CPN7 and CPN8 foraminifer Zones (N9, 10, 11 of the global foraminiferal zonation; and MMi4a; MMi5 and MMi6 of the Mediterranean foraminiferal zonation were recognized. Sedimentology was based on description of well core material, and together with SP and RT logs, used to characterize paleoenvironmental conditions of the deposition. Five sedimentary facies were reconstructed: (1 fan-delta to onshore environment which developed during the Lower Badenian; (2 followed by the Lower Badenian proximal slope gravity currents sediments; (3 distal slope turbidites were deposited in the Lower and Upper Badenian; (4 at the very end of the Upper Badenian and during the Sarmatian a coastal plain of normal marine to brackish environment developed; (5 sedimentation finished with the Pannonian-Pliocene shallow lacustrine to alluvial plain deposits. The provenance analysis records that the sediment of the well-cores was derived from crystalline basement granitoides and gneisses and from the Permian to Lower Cretaceous sedimentary cover and nappe units of the Western Carpathians and the Eastern Alps. Moreover, the Lower Badenian volcanism was an important source of sediments in the lower part of the sequence.

  15. Strategic groundwater resources in the Tagliamento River basin (northern Italy): hydrogeological investigation integrated with geophysical exploration

    Science.gov (United States)

    Rapti-Caputo, Dimitra; Bratus, Antonio; Santarato, Giovanni

    2009-09-01

    The western sector of the Tagliamento River basin (Friuli Venezia-Giulia Region; northern Italy) is characterized by important water resources, both superficial and underground. In particular, in the Quaternary deposits of the plain, up to a depth of 500 m, six artesian aquifer systems exist. A large amount of lithological, geomorphological, and hydrogeological data is presented, allowing for definition of (a) the principal aquifer system of the area to a depth of about 500 m; (b) geometrical characteristics of the aquifers (thickness, lateral extension, etc); (c) the hydraulic parameters (hydraulic conductivity, transmissivity); (d) chemico-physical characteristics of the water; and (e) vulnerability to pollution of the aquifer systems. In a test area, where many boreholes were drilled for fresh water supply, the conceptual hydrogeological model was integrated by a detailed and repeated three-dimensional (3D) resistivity survey using combined electrical resistivity tomography (ERT) and time-domain electromagnetic (TDEM) soundings. ERT investigation was mainly used to get detailed information about geometry and porosity of the overburden and to calibrate the shallowest TDEM information.

  16. Digital resource modeling of the northern and central Appalachian Basin coal regions: Top producing coals

    Energy Technology Data Exchange (ETDEWEB)

    Ruppert, L.; Tewalt, S.; Bragg, L.; Wallack, R.; Jenkins, J.; Tully, J. [Geological Survey, Reston, VA (United States)

    1998-12-31

    The US Geological Survey is currently conducting a coal resource assessment of the coal beds and zones that are expected to provide the bulk of the Nation`s coal resources for the next few decades. In partnership with the state geologic surveys of Kentucky, Tennessee, West Virginia, Virginia, Pennsylvania, Ohio, and Maryland, six coal beds will be digitally assessed in the northern and central Appalachian Basin coal region. In ascending stratigraphic order, the beds which range from the Lower Pennsylvanian Pocahontas Formation to the Upper Pennsylvanian Monongahela Group are the Pocahontas No. 3, Pond Creek, Fire Clay, Lower Kittanning, Upper Freeport, and Pittsburgh coals. Comprehensive stratigraphic and geochemical databases have been developed for the coal beds. Maps that show the extent and mined areas of the beds, structure contour, isopach, and overburden thickness have been compiled for the Pittsburgh coal bed and are in preparation for the other coal beds. The resource model for the Pittsburgh coal bed indicates that of the original 33.6 billion short tons (30.5 billion tonnes) of Pittsburgh coal, approximately 15.9 billion short tons (14.4 billion tonnes) remain. The remaining coal is, however, higher in ash and sulfur, and generally thinner and under thicker overburden cover.

  17. New palynological data from Karoo sediments, Mana Pools basin, northern Zimbabwe

    Science.gov (United States)

    d'Engelbronner, E. R.

    1996-07-01

    The palynological associations of 16 Karoo samples, collected in the Mana Pools basin, Northern Zimbabwe, were studied, and four zonal assemblages can be recognized. Assemblage I (Kondo Pools Formation) is dominated by monosaccate pollen grains and diverse alete bisaccate pollen grains occur frequently. Important but rare marker genera include Limitisporites, Vittatina and Weylandites. These indicate a middle to late Early Permian age (e.g. Late Sakmarian to Early Artinskian). The palynological assemblage, derived from the Massive Sandstone Member, Angwa Sandstone Formation, is characterized by a small number of smooth and apiculate spores, but is lacking any age significant marker taxa. Assemblages II and III, both from the Alternations Member (Angwa Sandstone Formation), and Assemblage IV (Pebbly Arkose Formation) are dominated by alete bisaccate and multitaeniate pollen grains. The rare occurrence of Vittatina, Weylandites lucifer and Guttulapollenites hannonicus indicates a Late Permian to Early Triassic age for Assemblage II. Based on sedimentological data and literature, a preliminary age of Early Triassic (Induan) can be given. A range from latest Fassanian (Ladinian) to Lacian (Norian) for Assemblage III is indicated by the occurrence of Asseretospora gyrata, Cadargasporites senectus, Eucommiidites, Infernopollenites, Minutosaccus crenulatus, Retisulcites perforatus and Samaropollenites speciosus. Small amounts of Asseretospora gyrata, Cadargasporites senectus, Cycadopites, Microcachryidites and Minutosaccus crenulatus indicate a slightly larger age range for Assemblage IV (e.g. Carnien to Rhaetian).

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Oscar Zúñiga

    2011-11-01

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

  20. Geology and coal-bed methane resources of the northern San Juan Basin, Colorado and New Mexico

    International Nuclear Information System (INIS)

    This guidebook is the first of its kind: A focused look at coal-bed methane in a large Rocky Mountain Laramide basin. The papers in this volume cover every aspect of coal-bed methane in the San Juan Basin, including: The geology, environments of deposition, and geometry of the coal beds that contain the resource; the origin and migration history of the gas; basin-wide resource estimates; the engineering aspects of getting the gas out of the ground; the marketing and economics of producing coal-bed methane in the San Juan Basin; the legal ownership of the gas; state regulations governing well spacing and field rules; disposal of produced water; and land and mineral ownership patterns in the northern part of the basin. Also included are detailed papers on all of the major coal-bed methane fields in the basin, and in a paper on the history of Fruitland gas production, a discussion of most of the not-so-major fields. A small section of the book deals with geophysical methods, as yet still experimental, for surface detection of underground hydrocarbon resources. Individual papers have been processed separately for inclusion on the data base

  1. Precipitation thresholds for triggering floods in Corgo hydrographic basin (Northern Portugal)

    Science.gov (United States)

    Santos, Monica; Fragoso, Marcelo

    2016-04-01

    The precipitation is a major cause of natural hazards and is therefore related to the flood events (Borga et al., 2011; Gaál et al., 2014; Wilhelmi & Morss, 2013). The severity of a precipitation event and their potential damage is dependent on the total amount of rain but also on the intensity and duration event (Gaál et al., 2014). In this work, it was established thresholds based on critical combinations: amount / duration of flood events with daily rainfall data for Corgo hydrographic basin, in northern Portugal. In Corgo basin are recorded 31 floods events between 1865 and 2011 (Santos et al., 2015; Zêzere et al., 2014). We determined the minimum, maximum and pre-warning thresholds that define the boundaries so that an event may occur. Additionally, we applied these thresholds to different flood events occurred in the past in the study basin. The results show that the ratio between the flood events and precipitation events that occur above the minimum threshold has relatively low probability of a flood happen. These results may be related to the reduced number of floods events (only those that caused damage reported by the media and produced some type of damage). The maximum threshold is not useful for floods forecasting, since the majority of true positives are below this limit. The retrospective analysis of the thresholds defined suggests that the minimum and pre warning thresholds are well adjusted. The application of rainfall thresholds contribute to minimize possible situations of pre-crisis or immediate crisis, reducing the consequences and the resources involved in emergency response of flood events. References Borga, M., Anagnostou, E. N., Blöschl, G., & Creutin, J. D. (2011). Flash flood forecasting, warning and risk management: the HYDRATE project. Environmental Science & Policy, 14(7), 834-844. doi: 10.1016/j.envsci.2011.05.017 Gaál, L., Molnar, P., & Szolgay, J. (2014). Selection of intense rainfall events based on intensity thresholds and

  2. The Post-Permian evolution of the Northern Part of the North German Basin

    Science.gov (United States)

    Hansen, M. B.; Huebscher, C.; Lykke-Andersen, H.; Gajewski, D.; Dehghani, A.; Reicherter, K.

    2004-12-01

    In the frame of the Priority Program 1135 of the German Research Foundation (DFG) "Dynamics of sedimentary systems under varying stress conditions by example of the Central European Basin System", the scientific goal of the NeoBaltic project is to describe the post-Permian to recent geological evolution of the entire western Baltic Sea region, with a special emphasis on neotectonic activity and it relation to salt dynamics. The western Baltic Sea comprises the northern part of the North German Basin (NGB), a part of the Central European Basin System (CEBS), and the transitional zone between the NGB and the Baltic Shield. In order to investigate these scientific goals the Universities of Aarhus (Denmark) and Hamburg (Germany) has since 1998 completed seven marine campaigns in the western Baltic Sea, collecting 2D high resolution seismic (HRS), gravity and magnetic data in the entire region during different projects. Since 2003 all these data has been available for the NeoBaltic project. All together the data pool have more than 7000 km HRS, 5000 km gravity and 4000 km magnetic data. Until now the project work has been focused on the completion of the data processing and the digital interpretation of important Mesozoic and Cenozoic markers on the seismic sections from the Bays of Kiel and Mecklenburg. Furthermore, several maps have been completed from the potential field data (gravity and magnetic). As a result of the digital interpretation of the HRS data, the overall geological evolution of the northern part of the NGB can be subdivided into four distinct periods. During the Triassic and the Early Jurassic, E-W extension and the deposition of clastic sediments initiated the movement of the underlying Zechstein evaporites. This is seen by the presence of several salt pillows in the region. The deposition ceased during the Middle Jurassic, when the entire area was uplifted, due to the Mid North Sea Doming. The uplift resulted in a pronounced erosion of Upper Triassic

  3. Hydrochemical and isotopic patterns in a calc-alkaline Cu- and Au-rich arid Andean basin: The Elqui River watershed, North Central Chile

    International Nuclear Information System (INIS)

    Highlights: ► Major ions are provided by rock weathering and NaCl recycling. ► Aridity and cal-alkaline lithology effects abate acid drainage. ► Factors affecting hydrochemistry in mineral rich zone are addressed. ► Stable isotopes confirm the meteoric origin of groundwaters. ► High sulfate contents are explained by widespread sulfide minerals. - Abstract: The geochemistry of surface water and groundwater from the Elqui River basin, North-Central Chile, was studied in spring 2007 and fall 2008 to obtain a general understanding of the factors and mechanisms controlling the water chemistry of steep rivers located in mineral-rich, arid to semi arid zones. Besides its uniform intermediate igneous lithology, this basin is known for acid drainage and high As contents in the El Indio Au–Cu–As district, in its Andean head. Abundant tailings deposits are present in the middle part of the basin, where agricultural activities are important. According to the results, the chemical and isotopic composition of the Elqui basin surface water and groundwater is related to uniform calc-alkaline lithology and the major polluting system of the chemically reactive, but closed El Indio mining district. The resulting compositional imprints in surface and ground-water are, (a) high SO4 levels, reaching about 1000 mg/L in the Toro River water, directly draining the mining area; (b) a major depletion of Fe and pollutant metals in surface water after the confluence of the Toro and La Laguna rivers; (c) similar chemical composition of surface and ground-waters that differ in H and O isotopic composition, reflecting the effect of differential evaporation processes downstream of the Puclaro dam; and (d) seasonal variations of Fe, Mn, Cu and Zn in surface water. In contrast, the groundwater chemistry exhibits moderate seasonal changes, mainly in HCO3- content. In spite of the acid drainage pollution, water quality is adequate for human consumption and irrigation. This is a

  4. Uplifted ophiolitic rocks on Isla Gordon, southernmost Chile: implications for the closure history of the Rocas Verdes marginal basin and the tectonic evolution of the Beagle Channel region

    Science.gov (United States)

    Cunningham, W. D.

    1994-04-01

    A succession of mafic rocks that includes gabbro, sheeted dikes and deformed pillow basalts has been mapped in detail on Isla Gordon, southernmost Chile and is identified as an upper ophiolitic complex representing the uplifted floor of the Late Jurassic-Early Cretaceous Rocas Verdes marginal basin. The complex was uplifted, deformed, and regionally metamorphosed prior to the intrusion of an undeformed 90 Ma granodiorite that cuts the complex. The complex appears para-autochthonous, is gently tilted to the northeast and is internally sheared by near-vertical foliation zones. No evidence for obduction was observed although the base of the complex is not exposed. The ophiolitic rocks have been regionally metamorphosed to mid-upper greenschist levels. Isla Gordon is bounded by the northwest and southwest arms of the Beagle Channel, two important structural boundaries in the southernmost Andes that are interpreted to have accommodated north-side-up and left-lateral displacements. Directly north of Isla Gordon is the Cordillera Darwin metamorphic complex that exposes the highest grade metamorphic rocks in the Andes south of Peru. On the north coast of Isla Gordon a volcaniclastic turbidite sequence that is interpreted to have been deposited above the mafic floor is metamorphosed to lower greenschist levels in strong metamorphic contrast to amphibolite-grade othogneisses exposed in Cordillera Darwin only 2 km away across the northwest arm of the Beagle Channel. The profound metamorphic break across the northwest arm of the Beagle Channel and the regional northeast tilt of the ophiolitic complex are consistent with the previously proposed hypothesis that Isla Gordon represents the upper plate to an extensional fault that accommodated tectonic unroofing of Cordillera Darwin. However, limited structural evidence for extension was identified in this study to support the model and further work is needed to determine the relative importance of contractional, extensional and

  5. 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

  6. The architecture of an incipient oceanic basin: a tentative reconstruction of the Jurassic Liguria-Piemonte basin along the Northern Apennines-Alpine Corsica transect

    Science.gov (United States)

    Marroni, Michele; Pandolfi, Luca

    2007-11-01

    In this paper, a scenario for the early evolution of the Jurassic oceanic Liguria-Piemonte basin is sketched. For this purpose, four selected examples of ophiolite sequences from the Northern Apennines and Corsica are described and analyzed. In the External Ligurian units (Northern Apennines), the ocean-continent transition of the Adria plate was characterized by a basement made up of subcontinental mantle and lower continental crust, covered by extensional allochthons of upper crust. Both, the basement rocks and the extensional allochthons are cut by basaltic dikes and covered by basalts and pelagic deposits. The conjugate ocean-continent transition of the Corsica margin, represented by the Balagne nappe (Corsica), was composed of mantle peridotites and gabbros covered by basaltic flows and minor breccias, that in addition include continent-derived clasts. By contrast, the innermost (i.e., closest to the ocean) preserved area observed in the Internal Ligurian (Northern Apennines) and Inzecca (Corsica) units consists of former morphological highs of mantle peridotites and gabbros, bordered by small basins where the basement is covered by a volcano-sedimentary complex, characterized by ophiolitic breccias and cherts interlayered with basaltic flows. The overall picture resulting from our reconstructions suggests an asymmetric architecture for the Liguria-Piemonte basin with a central area bounded by two different transition zones toward the continental margins. This architecture can be interpreted as the result of a rifting process whose development includes a final stage characterized by passive, asymmetric extension of the lithosphere along an east-dipping detachment fault system.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-02-01

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

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

    Science.gov (United States)

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

    2011-01-01

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

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

    Science.gov (United States)

    Ewiak, Oktawian; Victor, Pia; Oncken, Onno

    2015-02-01

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

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

    Science.gov (United States)

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

    2001-02-01

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

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

    Science.gov (United States)

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

    2015-03-01

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

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

    Science.gov (United States)

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

    2015-08-01

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

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

    Directory of Open Access Journals (Sweden)

    Anghel Brito

    2014-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Felipe Méndez-Abarca

    2012-06-01

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

  15. Palaeoclimatic oscillations in the Pliensbachian (Early Jurassic) of the Asturian Basin (Northern Spain)

    Science.gov (United States)

    Gómez, Juan J.; Comas-Rengifo, María J.; Goy, Antonio

    2016-05-01

    One of the main controversial themes in palaeoclimatology involves elucidating whether climate during the Jurassic was warmer than the present day and if it was the same over Pangaea, with no major latitudinal gradients. There has been an abundance of evidence of oscillations in seawater temperature throughout the Jurassic. The Pliensbachian (Early Jurassic) constitutes a distinctive time interval for which several seawater temperature oscillations, including an exceptional cooling event, have been documented. To constrain the timing and magnitude of these climate changes, the Rodiles section of the Asturian Basin (Northern Spain), a well exposed succession of the uppermost Sinemurian, Pliensbachian and Lower Toarcian deposits, has been studied. A total of 562 beds were measured and sampled for ammonites, for biochronostratigraphical purposes, and for belemnites, to determine the palaeoclimatic evolution through stable isotope studies. Comparison of the recorded latest Sinemurian, Pliensbachian and Early Toarcian changes in seawater palaeotemperature with other European sections allows characterization of several climatic changes that are likely of a global extent. A warming interval partly coinciding with a δ13Cbel negative excursion was recorded at the Late Sinemurian. After a "normal" temperature interval, with temperatures close to average values of the Late Sinemurian-Early Toarcian period, a new warming interval containing a short-lived positive δ13Cbel peak, developed during the Early-Late Pliensbachian transition. The Late Pliensbachian represents an outstanding cooling interval containing a δ13Cbel positive excursion interrupted by a small negative δ13Cbel peak. Finally, the Early Toarcian represented an exceptional warming period, which has been pointed out as being responsible for the prominent Early Toarcian mass extinction.

  16. Long-term geochemical connections between the Samoan hotspot and the northern Lau and North Fiji Basins

    Science.gov (United States)

    Price, A. A.; Jackson, M. G.; Blichert-Toft, J.; Hall, P. S.; Sinton, J. M.; Kurz, M. D.; Blusztajn, J.

    2013-12-01

    The Lau and North Fiji Basins provide a unique environment for the study of upper mantle flow around a subducting slab due to the juxtaposition of the Tonga Trench and the Samoan hotspot (Hart et al., 2004). Both geochemical and geophysical data suggest that material from the Samoan hotspot is leaking southward into the adjacent Lau Basin, but the direction and rate of mantle flow are difficult to constrain.Spatial variations in the isotope geochemistry of igneous rocks from the Lau Basin can provide a useful window on flow in the upper mantle. For example, some lavas from the Samoan hotspot exhibit high 3He/4He, and the observation of elevated 3He/4He at Rochambeau Bank in the nearby northern Lau Basin has been interpreted as the result of a 'finger-like' intrusion of Samoan-plume mantle into the region. However, high 3He/4He is rare even in Samoan lavas, so other geochemical signatures including radiogenic 87Sr/86Sr and Pb-isotopic compositions unique to the Samoan hotspot are useful for characterizing the spatial distribution of the Samoan component within the northern Lau and North Fiji Basins. We present analyses of a combination of geochemical tracers (He-Hf-Nd-Sr-Pb isotopes, major, and trace elements) measured on glasses from the northern Lau Basin and the North Fiji Basin. The samples have 3He/4He ratios that vary between 6 and 10.5 times atmospheric. The samples also show arange in isotopic values from extremely depleted (87Sr/86Sr=0.702892, 143Nd/144Nd=0.513218 and 176Hf/177Hf=0.283510 on a ridge 100km North of Fiji) to moderately enriched (87Sr/86Sr=0.703598, 143Nd/144Nd=0.512884 and 176Hf/177Hf=0.283082 in lavas fromPandora Ridge). Notably, moderately enriched isotopic compositions in Pandora Ridge lavas plot near Samoa's Upolu Island in isotope space, but are slightly shifted isotopically towards a depleted MORB mantle component. The new data suggestthat the western extent of the Samoan plume's influence in the region extends into both the

  17. The tomato borer, Tuta absoluta, invading the Mediterranean Basin, originates from a single introduction from Central Chile

    OpenAIRE

    Thomas Guillemaud; Aurélie Blin; Isabelle Le Goff; Nicolas Desneux; Maritza Reyes; Elisabeth Tabone; Anastasia Tsagkarakou; Laura Niño; Eric Lombaert

    2015-01-01

    The Lepidopteran pest of tomato, Tuta absoluta, is native to South America and is invasive in the Mediterranean basin. The species' routes of invasion were investigated. The genetic variability of samples collected in South America, Europe, Africa and Middle East was analyzed using microsatellite markers to infer precisely the source of the invasive populations and to test the hypothesis of a single versus multiple introductions into the old world continents. This analysis provides strong evi...

  18. Integrated Water Resource Management and Energy Requirements for Water Supply in the Copiapó River Basin, Chile

    OpenAIRE

    Francisco Suárez; Muñoz, José F.; Bonifacio Fernández; Jean-Marc Dorsaz; Christian K. Hunter; Christos A. Karavitis; Jorge Gironás

    2014-01-01

    Population and industry growth in dry climates are fully tied to significant increase in water and energy demands. Because water affects many economic, social and environmental aspects, an interdisciplinary approach is needed to solve current and future water scarcity problems, and to minimize energy requirements in water production. Such a task requires integrated water modeling tools able to couple surface water and groundwater, which allow for managing complex basins where multiple stakeho...

  19. Interaction of water components in the semi-arid Huasco and Limarí river basins, North Central Chile

    OpenAIRE

    Strauch, G; R. Oyarzún; F. Reinstorf; J. Oyarzún; M. Schirmer; K. Knöller

    2009-01-01

    For sustainable water resource management in semi-arid regions, sound information is required about interactions between the different components of the water system: rain/snow precipitation, surface/subsurface run-off, groundwater recharge. Exemplarily, the Huasco and Limarí river basins as water stressed river catchments have been studied by isotope and hydrochemical methods for (i) the origin of water, (ii) water quality, (iii) relations of surface and groundwater.

    App...

  20. Cretaceous to Paleogene geology of the Salar de Atacama basin, northern Chile : a reappraisal of the Purilactis Group stratigraphy

    OpenAIRE

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

    1999-01-01

    De nouvelles données stratigraphiques, géochronologiques, structurales et paléomagnétiques acquises lors de l'étude de la bordure orientale de la Cordillère de Domeyko à la latitude du Salar d'Atacma nous permettent de préciser la stratigraphie du Groupe Purilactis. Celui-ci comprend une succession de 7 séquences sédimentaires et volcaniques. L'observation de la polarité normale dans les unités inférieures du Groupe Purilactis suggère un âge crétacé moyen pour ces unités. Les noveaux âges rad...

  1. A review of tectonics and sedimentation in a forearc setting: Hellenic Thrace Basin, North Aegean Sea and Northern Greece

    Science.gov (United States)

    Maravelis, A. G.; Boutelier, D.; Catuneanu, O.; Seymour, K. St.; Zelilidis, A.

    2016-04-01

    Exposure of the forearc region of the North Aegean Sea, Greece, offers insight into evolving convergent margins. The sedimentary fill of the Thrace Basin during the Late Eocene to Oligocene time provides a record of subduction-driven processes, such as growth of magmatic arcs and construction of accretionary complexes. This large sediment repository received sediment from two sources. The southern (outboard) basin margin reflects the active influence of the exhumed accretionary prism (e.g. Pindic Cordillera or Biga peninsula), while the northern (inboard) margin records the effect of the magmatic arc in the Rhodope region. The forearc basin sedimentary fills shoal upward into shallow-marine strata but are dominated mainly by deep-marine facies. The depositional trend and stacking pattern are dominated by progradational patterns. This trend, which is observed in both basin margins, is related to tectonic deformation rather than sea-level fluctuations. Additional evidence for this tectonic uplift comes from the backstripping analysis. The accretionary complex provided material into the forearc basin. This material was transported northeast and formed a sand-rich turbidity system that evolved upslope into shallow-marine deposits. Stratigraphic data indicate that this turbidity system exhibits a successive landward (inboard) migration of the depocenter. Provenance data utilizing sandstone petrography, conglomerate clast composition, and bulk-rock geochemistry suggest that this system reflects an increased influx of mafic material into the basin. Volcanic arc-derived material was transported south and east and accumulated in deep-marine settings. Both stratigraphic and provenance data indicate a seaward (outboard) migration of the basin depocenter and a significant increase in felsic detritus into the forearc.

  2. Stress state variations among the clay and limestone formations of the molasse basin of Northern Switzerland

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Full text of publication follows: The design of geological repositories for radioactive waste responds to the requirements of technical feasibility and long-term safety in the context of a specific geological setting. An important aspect of the geological setting is the primary stress field. To a large extent the stress state controls repository induced effects such as the excavation damage zone and the associated potential changes in the waste isolation properties of the host rock. Therefore the measurement of the stress state receives some attention where the site selection for geological repositories focuses onto relatively weak host rocks such as clay-stones and marly shales that tend to develop a significant excavation damage zone. Measurements of the minimum stress magnitudes in a recently drilled geothermal well in the Molasse Basin of northern Switzerland have yielded a stress profile reaching from 592 m to 1455 m depth. It straddles several rock units and includes the top of the crystalline basement. The sedimentary sequence consists of Marine limestones, shales and marls unconformably covered by Tertiary rocks of the Molasse. In other parts of the basin the evaporitic rocks of the Triassic Muschelkalk formation at the base of the sedimentary layer served as a regional detachment and enabled thin skinned thrusting and the formation of the Jura Fold and Thrust Belt in the Late Miocene. The stress measurements have been performed in the open hole by Mini-frac tests. The method uses a double packer system to isolate a one meter long interval of the borehole that is then pressurized at high injection rates up to the breakdown of the formation. Repeated pressurization of the interval allows to determine the stress that acts on the newly created fracture. The total injected volume during such a test is in the range of a few litres and the size of the fracture that extends from the borehole normal to the minimum

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

    Science.gov (United States)

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

    2016-01-01

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

  4. Thermal-rheological structure of lithosphere beneath the northern flank of Tarim Basin, western China:Implications for geodynamics

    Institute of Scientific and Technical Information of China (English)

    LIU; Shaowen; WANG; Liangshu; LI; Cheng; LI; Hua; HAN; Yong

    2004-01-01

    Based on the data of geo-temperature and thermophysical parameters of rocks in the Kuqa Depression and the Tabei Uplift, northern flank of the Tarim Basin, in terms of the analytical solution of 1-D heat transfer equation, the thermal structure of the lithosphere under this region is determined. Our results show that the average surface heat flow of the northern flank of the Tarim Basin is 45 mW/m2, and the mantle heat flow is between 20 and 23 mW/m2; the temperature at crust-mantle boundary (Moho) ranges from 514℃ to 603℃ and the thermal lithosphere where the heat conduction dominates is 138-182 km thick. Furthermore, in combination with the P wave velocity structure resulting from the deep seismic sounding profile across this region and rheological modeling, we have studied the local composition of the lithosphere and its rheological profile, as well as the strength distribution. We find that the rheological stratification of the lithosphere in this region is apparent. The lowermost of the lower crust is ductile; however,the uppermost of the mantle and the upper and middle parts of the crust are both brittle layers,which is typically the so-called sandwich-like structure. Lithospheric strength is also characterized by the lateral variation, and the uplift region is stronger than the depression region. The lithospheric strength of the northem flank of the Tarim Basin decreases gradually from south to north; the Kuqa Depression has the lowest strength and the south of the Tabei Uplift is strongest.The total lithospheric strength of this region is 4.77× 1012-5.03 × 1013 N/m under extension, and 6.5 × 1012-9.4× 1013 N/m under compression. The lithospheric brittle-ductile transition depth is between 20 km and 33 km. In conclusion, the lithosphere of the northern flank of the Tarim Basin is relatively cold with higher strength, so it behaves rigidly and deforms as a whole, which is also supported by the seismic activity in this region. This rigidity of the

  5. Cadenas operativas en la manufactura de arte rupestre: un estudio de caso en El Mauro, valle cordillerano del Norte Semiárido de Chile Rock Art Chaînes Opératoires: A Case Study From El Mauro, A Mountainous Valley In Semiarid Northern Chile

    Directory of Open Access Journals (Sweden)

    César A. Méndez Melgar

    2008-12-01

    Full Text Available Los contextos de producción son temas marginales en las discusiones relativas al arte rupestre. Independiente de los factores que hayan producido este sesgo en la comprensión del tema, se plantea que un examen a los procesos de manufactura es central para dar cuenta cabal del fenómeno rupestre. Se sugiere que el acto mismo de elaborar motivos es un acto comunicativo, tan cargado de contenidos sociales como podría pensarse que es la imagen misma, la cual ha recibido mayor atención en los estudios especializados. Se presenta un trabajo que expone una serie de procedimientos metodológicos destinados a entender la manufactura de petroglifos a través de sus instrumentos de trabajo y sus contextos de hallazgo. El área seleccionada fue El Mauro, valle cordillerano del Norte Semiárido, en donde se observa una profusión de estas manifestaciones para fechas del Holoceno tardío. Se discute una estrategia metodológica implementada a la luz de la noción que todo acto tecnológico es un acto social, se definen los instrumentos usados y se exponen una visión sintética del proceso a modo de una cadena operativa.Rock art production is a marginal issue in specialized discussions. Independently of the reasons for this bias in the current understanding of the subject, it is argued that an examination of production processes is crucial in order to fully account for the phenomenon. It is suggested that the elaboration of motifs is itself a communicative act, as loaded with social content as the images themselves, which have received more attention in specialized studies. This paper proposes a series of methodological procedures aimed at understanding rock art production through its production tools and recovery contexts. The study area comprises El Mauro mountain basin in semiarid northern Chile, where there is a high density of these manifestations from the late Holocene. A methodological strategy is discussed in light of the idea that every

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

    Directory of Open Access Journals (Sweden)

    Gerhard Wörner

    2000-12-01

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

  7. FACIES ANALYSIS, STRATIGRAPHY AND PALAEONTOLOGY (MOLLUSCS AND VERTEBRATES IN THE UPPER PLIOCENE SANDY FLOOD-BASIN DEPOSITS OF THE UPPER VALDARNO BASIN (NORTHERN APENNINES

    Directory of Open Access Journals (Sweden)

    MASSIMILIANO GHINASSI

    2005-11-01

    Full Text Available The Upper Valdarno Basin, one of the most investigated Neogene–Quaternary basins of the Northern Apennines, developed during three main phases, as testified by the occurrence of three unconformity-bounded stratigraphic units (UBSUs in the basin infill. Despite numerous studies having been carried out, biochronological, paleoecological and stratigraphical issues in the lower portion of the Montevarchi Synthem (second phase have yet to be understood. Sandy deposits (Montecarlo Sand and Silt Unit, stratigraphically located in this portion of the Montevarchi Synthem, are the focus of this multidisciplinary study. These deposits conformably overlie sandy fluvio-eolian sediments and are, in turn, capped by fluvio-palustrine deposits through a progressive unconformity. Facies analysis suggest a sandy flood-basin environment for these deposits, characterised by variations in water discharge and flood event energy. Mollusc and fish remains, pointing to quiet or slow-moving shallow waters, have been affected by transport processes before final burial in overbank areas. Fish remains of the primary marine family Mugilids highlight a connection between the basin and the sea that was previously only supposed. Small mammal remains, referred to the rodent Mimomys polonicus, are coherent with a water-rich environment. Cyclic variations in shell content and sedimentological characteristics testify to the occurrence of short-term climatic oscillations during this warming phase. This study fits with paleomagnetic and radiometric datings and mammal biochronology, in indicating that the Montecarlo Sand and Silt Unit belongs to a time interval preceding the Reunion paleomagnetic event. The depositional evolution of the Montecarlo Unit was driven by climatic change from arid to humid conditions, related to a global increase in temperature that occurred between 2.4 and 2.2 Ma.

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

    OpenAIRE

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

    2007-01-01

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

  9. Interaction of water components in the semi-arid Huasco and Limarí river basins, North Central Chile

    Directory of Open Access Journals (Sweden)

    G. Strauch

    2009-10-01

    Full Text Available For sustainable water resource management in semi-arid regions, sound information is required about interactions between the different components of the water system: rain/snow precipitation, surface/subsurface run-off, groundwater recharge. Exemplarily, the Huasco and Limarí river basins as water stressed river catchments have been studied by isotope and hydrochemical methods for (i the origin of water, (ii water quality, (iii relations of surface and groundwater.

    Applying the complex multi-isotopic and hydrochemical methodology to the water components of the Huasco and Limarí basins, a differentiation of water components concerning subsurface flow and river water along the catchment area and by anthropogenic impacts are detected. Sulphate and nitrate concentrations indicate remarkable input from mining and agricultural activities along the river catchment.

    The 2H-18O relations of river water and groundwater of both catchments point to the behaviour of river waters originated in an arid to semi-arid environment.

    Consequently, the groundwater from several production wells in the lower parts of the catchments is related to the rivers where the wells located, however, it can be distinguished from the river water. Using the hydrological water balance and the isotope mixing model, the interaction between surface and subsurface flows and river flow is estimated.

  10. Cheatgrass percent cover change: Comparing recent estimates to climate change − Driven predictions in the Northern Great Basin

    Science.gov (United States)

    Boyte, Stephen P.; Wylie, Bruce K.; Major, Donald J.

    2016-01-01

    Cheatgrass (Bromus tectorum L.) is a highly invasive species in the Northern Great Basin that helps decrease fire return intervals. Fire fragments the shrub steppe and reduces its capacity to provide forage for livestock and wildlife and habitat critical to sagebrush obligates. Of particular interest is the greater sage grouse (Centrocercus urophasianus), an obligate whose populations have declined so severely due, in part, to increases in cheatgrass and fires that it was considered for inclusion as an endangered species. Remote sensing technologies and satellite archives help scientists monitor terrestrial vegetation globally, including cheatgrass in the Northern Great Basin. Along with geospatial analysis and advanced spatial modeling, these data and technologies can identify areas susceptible to increased cheatgrass cover and compare these with greater sage grouse priority areas for conservation (PAC). Future climate models forecast a warmer and wetter climate for the Northern Great Basin, which likely will force changing cheatgrass dynamics. Therefore, we examine potential climate-caused changes to cheatgrass. Our results indicate that future cheatgrass percent cover will remain stable over more than 80% of the study area when compared with recent estimates, and higher overall cheatgrass cover will occur with slightly more spatial variability. The land area projected to increase or decrease in cheatgrass cover equals 18% and 1%, respectively, making an increase in fire disturbances in greater sage grouse habitat likely. Relative susceptibility measures, created by integrating cheatgrass percent cover and temporal standard deviation datasets, show that potential increases in future cheatgrass cover match future projections. This discovery indicates that some greater sage grouse PACs for conservation could be at heightened risk of fire disturbance. Multiple factors will affect future cheatgrass cover including changes in precipitation timing and totals and

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

    Science.gov (United States)

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

    2012-04-01

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

  12. Past, present and future formation of groundwater resources in northern part of Baltic Artesian Basin

    Science.gov (United States)

    Marandi, A.; Vallner, L.; Vaikmae, R.; Raidla, V.

    2012-04-01

    Cambrian-Vendian Aquifer System (CVAS) is the deepest confined aquifer system used for water consumption in northern part of Baltic Artesian Basin (BAB). A regional groundwater flow and transport model (Visual Modflow) was used to investigate the paleohydrogeological scientific and contemporary management problems of CVAS. The model covers the territory of Estonia and its close surrounding, all together 88,000 km2 and includes all main aquifers and aquitards from ground surface to as low as the impermeable part of the crystalline basement. Three-dimensional distribution of groundwater heads, flow directions, velocities, and rates as well as transport and budget characteristics were simulated by the model. Water composition was changed significantly during the last glaciations.Strongly depleted O and H stable isotope composition, absence of 3H and low radiocarbon concentration are the main indicators of glacial origin of groundwater in the Cambrian-Vendian aquifer in northern Estonia. The noble gas analyses allowed concluding, that palaeorecharge took place at temperatures around the freezing point. While in North Estonia, most of water was changed by glacial melt water, high salinity water is till preserved in Southern part of Estonia.First results of modeling suggest that during the intrusion period lasting 7.3-9.3 ka the front of glacial thaw water movement had southeast direction and reachedto 180-220 kmfrom CVAS outcrop in Baltic Sea. Confining layer of CVAS is cut through by deep buried valleys in several places in North Estonia making possible for modern precipitation to infiltrate into aquifer system in present day. In case of natural conditions, the water pressure of CVAS is few meters above sea level and most of valleys act as discharge areas for aquifers system. Two regional depression ones have formed in North Estonia as a result of groundwater use from CVAS. Water consumption changes the natural groundwater gradient, flow direction and thereforerecharge

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

    Science.gov (United States)

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

    2015-12-01

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

  14. Review of the Upper Jurassic-Lower Cretaceous stratigraphy in Western Cameros basin, Northern Spain

    DEFF Research Database (Denmark)

    Vidal, Maria del Pilar Clemente

    2010-01-01

    The Upper Jurassic-Lower Cretaceous stratigraphy of the Cameros basin has been reviewed. In Western Cameros the stratigraphic sections are condensed but they have a parallel development with the basin depocentre and the same groups have been identified. The Tera Group consists of two formations...

  15. Structure of the Wagner Basin in the Northern Gulf of California From Interpretation of Seismic Reflexion Data

    Science.gov (United States)

    Gonzalez, M.; Aguilar, C.; Martin, A.

    2007-05-01

    The northern Gulf of California straddles the transition in the style of deformation along the Pacific-North America plate boundary, from distributed deformation in the Upper Delfin and Wagner basins to localized dextral shear along the Cerro Prieto transform fault. Processing and interpretation of industry seismic data adquired by Petroleos Mexicanos (PEMEX) allow us to map the main fault structures and depocenters in the Wagner basin and to unravel the way strain is transferred northward into the Cerro Prieto fault system. Seismic data records from 0.5 to 5 TWTT. Data stacking and time-migration were performed using semblance coefficient method. Subsidence in the Wagner basin is controlled by two large N-S trending sub-parallel faults that intersect the NNW-trending Cerro Prieto transform fault. The Wagner fault bounds the eastern margin of the basin for more than 75 km. This fault dips ~50° to the west (up to 2 seconds) with distinctive reflectors displaced more than 1 km across the fault zone. The strata define a fanning pattern towards the Wagner fault. Northward the Wagner fault intersects the Cerro Prieto fault at 130° on map view and one depocenter of the Wagner basin bends to the NW adjacent to the Cerro Prieto fault zone. The eastern boundary of the modern depocenter is the Consag fault, which extends over 100 km in a N-S direction with an average dip of ~50° (up to 2s) to the east. The northern segment of the Consag fault bends 25° and intersects the Cerro Prieto fault zone at an angle of 110° on map view. The acoustic basement was not imaged in the northwest, but the stratigraphic succession increases its thickness towards the depocenter of the Wagner basin. Another important structure is El Chinero fault, which runs parallel to the Consag fault along 60 km and possibly intersects the Cerro Prieto fault to the north beneath the delta of the Colorado River. El Chinero fault dips at low-angle (~30°) to the east and has a vertical offset of about 0

  16. Evolution of the Neogene Andean foreland basins of the Southern Pampas and Northern Patagonia (34°-41°S), Argentina

    Science.gov (United States)

    Folguera, Alicia; Zárate, Marcelo; Tedesco, Ana; Dávila, Federico; Ramos, Victor A.

    2015-12-01

    The Pampas plain (30°-41°S) has historically been considered as a sector that evolved independently from the adjacent Andean ranges. Nevertheless, the study of the Pampas showed that it is reasonable to expect an important influence from the Andes into the extraandean area. The Pampas plain can be divided into two sectors: the northern portion, adjacent to the Pampean Ranges, has been studied by Davila (2005, 2007, 2010). The southern sector (34°-41°S) is the objective of the present work. The study of this area allowed to characterize two separate foreland basins: the Southern Pampa basin and the Northern Patagonian basin. The infill is composed of Late Miocene and Pliocene units, interpreted as distal synorogenic sequences associated with the late Cenozoic Andean uplift at this latitudinal range. These foreland basins have been defined based on facies changes, distinct depositional styles, along with the analysis of sedimentary and isopach maps. The basins geometries are proposed following De Celles and Gilles (1996) taking into account the infill geometry, distribution and grain size. In both cases, these depocenters are located remarkably far away from the Andean tectonics loads. Therefore they cannot be explained with short-wave subsidence patterns. Elastic models explain the tectonic subsidence in the proximal depocenters but fail to replicate the complete distal basins. These characteristics show that dynamic subsidence is controlling the subsidence in the Southern Pampas and Northern Patagonian basins.

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

    Directory of Open Access Journals (Sweden)

    R. Torres

    2010-03-01

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

  18. Hydrological application of the INCA model with varying spatial resolution and nitrogen dynamics in a northern river basin

    Directory of Open Access Journals (Sweden)

    K. Rankinen

    2002-01-01

    Full Text Available As a first step in applying the Integrated Nitrogen model for CAtchments (INCA to the Simojoki river basin (3160 km2, this paper focuses on calibration of the hydrological part of the model and nitrogen (N dynamics in the river during the 1980s and 1990s. The model application utilised the GIS land-use and forest classification of Finland together with a recent forest inventory based on remote sensing. In the INCA model, the Hydrologically Effective Rainfall (HER is used to drive the water flow and N fluxes through the catchment system. HER was derived from the Watershed Simulation and Forecast System (WSFS. The basic component of the WSFS is a conceptual hydrological model which simulates runoff using precipitation, potential evapotranspiration and temperature data as inputs. Spatially uniform, lumped input data were calculated for the whole river basin and spatially semi-distributed input data were calculated for each of the nine sub-basins. When comparing discharges simulated by the INCA model with observed values, a better fit was obtained with the semi-distributed data than with the spatially uniform data (R2 0.78 v. 0.70 at Hosionkoski and 0.88 v. 0.78 at the river outlet. The timing of flow peaks was simulated rather well with both approaches, although the semi-distributed input data gave a more realistic simulation of low flow periods and the magnitude of spring flow peaks. The river basin has a relatively closed N cycle with low input and output fluxes of inorganic N. During 1982-2000, the average total N flux to the sea was 715 tonnes yr–1, of which 6% was NH4-N, 14% NO3-N, and 80% organic N. Annual variation in river flow and the concentrations of major N fractions in river water, and factors affecting this variation are discussed. Keywords: northern river basin, nitrogen, forest management, hydrology, dynamic modelling, semi-distributed modelling

  19. Paleoenvironmental and source rock assessment of black shales of Pennsylvanian Age, Powder River and northern Denver basins

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, J.L.; King, J.D.; Lubeck, C.M.; Leventhal, J.S.; Daws, T.A.

    1988-07-01

    Thin Middle Pennsylvanian (Desmoinesian) organic-rich black shales (cumulative thickness < 50 ft) underlie much of the northern Denver basin and southeastern Powder River basin. In the Powder River basin, these shales are part of the middle member of the Minnelusa Formation. During Desmoinesian time, the present area of the southeastern Powder River basin and Nebraska was a shallow, at times highly saline, restricted sea. In contrast, in the present area of northeastern Colorado, black shales were deposited in a marine environment with normal salinity that was probably continuous with the Mid-Continent Pennsylvanian sea. Assessment of the paleoenvironment has been carried out using organic geochemical parameters. Shales deposited in the restricted basin setting contain abundant porphyrins (25,000-30,000 ppm relative to total extractable organic matter) and significant quantities of aryl isoprenoids. The aryl isoprenoid compounds (1) are evidence for the presence of the sulfur bacteria families Chlorobiaceae and possibly Chromatiaceae and (2) indicate that euxinic conditions existed in the water column. High ratios of sulfur to carbon in the shales support this interpretation. In contrast, extracts from black shale in the normal sea to the south contain lower porphyrin concentrations (generally less than 1000 ppm) and aryl isoprenoids are minor constituents or are absent. Sulfur/carbon ratios in these latter shales are similar to those observed for normal marine shales (that is, not euxinic conditions). Other paleoenvironmental indicators (sterane composition, alkane distribution) are consistent with these observations. Bulk organic matter in the black shales from both environments is type II and has good source potential for generation of liquid hydrocarbons during catagenesis. Pyrolysis yields of 50 kg/MT (50,000 ppm) are common, and in some shales, yield is 100 kg/MT (100,000 ppm).

  20. Gas hydrate formation and accumulation potential in the Qiangtang Basin, northern Tibet, China

    International Nuclear Information System (INIS)

    Highlights: • Qiangtang Basin is the biggest residual petroleum-bearing basin in Tibet Plateau. • The Late Triassic Tumen Gela Formation is the most important gas source rock. • Seventy-one potential anticline structural traps have been found. • A favorable geothermal condition for gas hydrate formation. • A large number of mud volcanoes were discovered in the basin. - Abstract: The Qiangtang Basin is the biggest residual petroleum-bearing basin in the Qinghai–Tibet Plateau, and is also an area of continuous permafrost in southwest China with strong similarities to other known gas-hydrate-bearing regions. Permafrost thickness is typically 60–180 m; average surface temperature ranges from −0.2 to −4.0 °C, and the geothermal gradient is about 2.64 °C/100 m. In the basin, the Late Triassic Tumen Gela Formation is the most important gas source rock for gas, and there are 34.3 × 108 t of gas resources in the Tumen Gela Formation hydrocarbon system. Seventy-one potential anticline structural traps have been found nowadays covering an area of more than 30 km2 for each individual one, five of them are connected with the gas source by faults. Recently, a large number of mud volcanoes were discovered in the central Qiangtang Basin, which could be indicative of the formation of potential gas hydrate. The North Qiangtang depression should be delineated as the main targets for the purpose of gas hydrate exploration

  1. Subaqueous landslides at the distal basin of Lago Nahuel Huapi (Argentina): Towards a tsunami hazard evaluation in Northern Patagonian lakes

    Science.gov (United States)

    Beigt, Débora; Villarosa, Gustavo; Gómez, Eduardo A.; Manzoni, Carolina

    2016-09-01

    The May 22nd, 1960 Valdivia earthquake, Chile (Mw 9.5) triggered a series of subaqueous mass-wasting processes (debris flows and slides) in Lago Nahuel Huapi (Argentina), generating a tsunami-like wave that hit the coasts of San Carlos de Bariloche. Aiming to provide a first preliminary insight into tsunami hazards for the lakeshore communities, in this paper we identify and characterize the subaqueous landslides at the populated distal basin of the lake. Swath bathymetric and seismic profiling surveys were carried out and high-resolution digital elevation models were derived from these data to perform a landslide inventory map. A series of morphometrical parameters (including the landslide area, the volume of displaced materials and the run-out distance, among others) were estimated upon selected events. The results indicated that landslide activity at the distal basin of Lago Nahuel Huapi has been concentrated in the vicinity of Bariloche (massive landslide triggered by the 1960 earthquake) and within steep delta fronts where the slope failures typically initiate at shallow waters (9-11 m depth). The sliding mass frequently travels basinward along a great distance (≥ 1000 m). At the delta fronts, the volume of material removed by landslides can reach ~ 40 × 104 m3, leaving scar areas of up to 13 m thick. The periodic occurrence of rotational-translational mass movements initiating at the upper edge of the delta fronts, with vertical displacements of the mobilized materials reaching ~ 200 m, probably represents a potential tsunami hazard for the nearby populated coasts.

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

    Science.gov (United States)

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

    2016-04-01

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

  3. Seismo-stratigraphic evolution of the northern Austral Basin and its possible relation to the Andean tectonics, onshore Argentina.

    Science.gov (United States)

    Sachse, Victoria; Anka, Zahie; Pagan, Facundo; Kohler, Guillermina; Cagnolatti, Marcelo; di Primio, Rolando; Rodriguez, Jorge

    2013-04-01

    The Austral Basin is situated in a formerly and recently high active tectonic zone in southern Argentina. The opening of the South Atlantic to the east, the opening of the Drake Passage in the south, and the subduction related to the rise of the Andes to the west, had major influence on the study area. To identify the impact of the tectonic events on basin geometry, sediment thickness and depocenter migration through time, 2D seismic interpretation was performed for an area of approx. 180.000 km² covering the onshore northern Austral Basin. A total of 10 seismic horizons were mapped and tied to the stratigraphy from well reports, representing 9 syn- and post- rift sequences. The main units are: Basement (U1), Jurassic Tobifera Formation (U2), Early Cretaceous (U3), Late Cretaceous (U4), sub-unit Campanian (U4A), Paleocene (U5), Eocene (U6), Oligocene (U7), Miocene (U8), and Plio-Pleistocene (U9). Main tectonic events are identified representing the break-up phase forming graben systems and the evolution from the ancient backarc Rocas Verdes Basin to the foreland Austral Basin. Inversion and changes in the tectonic regime are concomitant with onlapping and thinning of the base of the Upper Cretaceous to Campanian sediments, while the Top of the Upper Cretaceous represents a Maastrichtian unconformity. Units depth maps show a triangular geometry since the Jurassic, tracing the north-eastern basement high and deepening to the south. Since the Campanian the former geometry of basin fill changed and deepening to the south stopped. Beginning of the foreland phase is assigned to this time as well as changes in the stress regime. Paleogene times are marked by a relatively high sedimentation rate coupled with enduring thermal subsidence, on-going rise of the Andes and changes in the convergence rates of the Nazca relative to the South American plate. Onset of sediment supply from the Andes (Incaic phase) resulted in enhanced sedimentation rates during the Paleocene

  4. Raft tectonics in northern Campos Basin; Tectonica de jangada (raft tectonics) na area norte da Bacia de Campos

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Marilia R. de [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacases, RJ (Brazil)]|[PETROBRAS, Macae, RJ (Brazil). Unidade de Negocio da Bacia de Campos; Fugita, Adhemar M. [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Programa de Recursos Humanos da ANP

    2004-07-01

    In the northern area of Campos Basin salt gliding/spreading processes promoted the break-up and transport of Cretaceous and Tertiary rocks overlying the evaporites. This process is known as raft tectonics, and it represents the most extreme form of thin-skinned extension above the salt decollement surface. Three distinct geotectonic domains were recognized that formed in response to the raft tectonics. The first one, confined to the shallower shelf portion of the basin, is characterized by minor extension (pre-raft domain), probably because of small salt thickness and low gradient. In the second domain (or disorganized rafts domain), located in distal platformal and slope areas, seismic sections show the occurrence of blocks or rafts with angular shapes, sometimes imbricated and frequently discontinuous. In the third domain, or domain of organized rafts, located in bacinal region, seismic sections show a more continuous raft pattern, often folded because of salt compression in the distal portions of the basin. The main purposes of this work is to characterize these three tectonic domains distinguished by raft tectonics, as well as their importance in hydrocarbon accumulations in calcarenites. (author)

  5. Geologic implications of large-scale trends in well-log response, northern Green River Basin, Wyoming

    International Nuclear Information System (INIS)

    Well-log response in lower Tertiary and Upper Cretaceous rocks in the northern Green River basin, Wyoming, is examined. Digitally recorded well-log data for selected wells located throughout the basin were processed by computer and displayed as highly compressed depth-scale plots for examining large-scale geologic trends. Stratigraphic units, formed under similar depositional conditions, are distinguishable by differing patterns on these plots. In particular, a strong lithologic contrast between Tertiary and underlying Upper Cretaceous non-marine clastic rocks is revealed and correlated through the study area. Laboratory analysis combined with gamma-ray spectrometry log data show that potassium feldspars in the arkosic Tertiary sandstones cause the contrast. The nature and extent of overpressuring has been examined. Data shift on shale conductivity and shale acoustic transit-time plots, previously ascribed to changes in pore pressure, correspond to stratigraphic changes and not necessarily with changes in pore pressure as indicated by drilling-mud weights. Gulf Coast well-log techniques for detecting overpressuring are unreliable and ineffectual in this basin, which has experienced significantly different geologic depositional and tectonic conditions

  6. The linkage between longitudinal sediment routing systems and basin types in the northern South China Sea in perspective of source-to-sink

    Science.gov (United States)

    Su, Ming; Hsiung, Kan-Hsi; Zhang, Cuimei; Xie, Xinong; Yu, Ho-Shing; Wang, Zhenfeng

    2015-11-01

    Using bathymetric and seismic data, this study describes the morpho-sedimentary features in Qiongdongnan basin and southwest Taiwan collision basin, northern South China Sea and reveals the linkages between sediment routing system and basin types. The modern Central Canyon in the Qiongdongnan basin is located along the rift margin, and subparallel to the shelf-break southeast of Hainan Island. The modern Central Canyon develops along the basin axis (i.e., Xisha Trough) and longitudinally transports sediments eastward which are mainly supplied by northern continental slope. The Penghu Canyon in the southwest Taiwan collision basin is located along the collision boundary parallel to the strike of the adjacent uplifted Taiwan orogen. The Penghu Canyon develops along the tilting basin axis transporting sediments longitudinally southward to the deep-sea basin and Manila Trench. The Penghu Canyon is supplied with sediments from both flank Kaoping and South China Sea slopes where tributary canyons and channels transport sediments down-slope and feed the axial canyon. The certain basin types may be occupied by particular styles of sediment routing system. By comparing the morpho-sedimentary features and basin characteristics associated with the modern Central Canyon to that of the Valencia Channel in NW Mediterranean Sea, the longitudinal sediment routing system in rift basin type can be determined. In contrast, the longitudinal sediment routing systems in collision setting can be represented by the comparable examples of Penghu Canyon in southwest Taiwan collision basin and Markham Canyon in western Solomon Sea. The rift type sediment routing system is characterized by an axial canyon with a single sediment supply from land drainage margin. In contrast, sediment routing system in collision type basins consists of an axial canyon and dual sediment supplies from flank adjacent slopes. The axial canyons in collision basins are more active than that of the rift basin due to

  7. Neotectonic aspects of the northern margin of the Adana–Cilicia submarine basin, NE Mediterranean

    Indian Academy of Sciences (India)

    E Ozel; A Ulug; B Pekcetinoz

    2007-04-01

    The sedimentary basins that dominate the north-eastern Mediterranean (Adana–Cilicia basins in the west and Iskenderun basin in the east) are located on the flanks of a partly submerged positive structure (a part of the Africa–Eurasia convergence zone) along which strike-slip faults are evident. This study summarizes the findings of two seismic surveys carried out in the Alanya– Mersin offshore region. Some 850 km of geophysical survey lines were compiled on these cruises. Based on the results determined from these surveys, the north and central part of Adana–Cilicia basin can be subdivided into eastern, central and western structural sub-basins separated by the Ecemiş fault complex in the east and the Anamur–Kormakiti structural high in the west at the same time. Results of this study also indicate that Ecemiş and Anamur–Kormakiti faults are active. Late Miocene regional compression was responsible for the compartmentation of this complex into the present arrangement and has initiated the rotational regime which has governed subsequent tectonic developments, notably the extensional behaviour of the NE–SW trending Ecemiş and Anamur–Kormakiti faults and the transpressive behaviour of the NNE–SSW trending border fault complex.

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

    OpenAIRE

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

    2003-01-01

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

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

    OpenAIRE

    Marianela Medina; Hugo Arancibia

    2002-01-01

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

  10. Paleogeographic significance of Upper Triassic basinal succession of the Tamar Valley, northern Julian Alps (Slovenia

    Directory of Open Access Journals (Sweden)

    Gale Luka

    2015-08-01

    Full Text Available The Julian Alps (western Slovenia structurally belong to the eastern Southern Alps. The Upper Triassic succession mostly consists of shallow water platform carbonates of the Dolomia Principale-Dachstein Limestone system and a deep water succession of the Slovenian Basin outcropping in the southern foothills of the Julian Alps. In addition to the Slovenian Basin, a few other intraplatform basins were present, but they remain poorly researched and virtually ignored in the existing paleogeographic reconstructions of the eastern Southern Alps. Herein, we describe a deepening-upward succession from the Tamar Valley (north-western Slovenia, belonging to the Upper Triassic Tarvisio Basin. The lower, Julian-Tuvalian part of the section comprises peritidal to shallow subtidal carbonates (Conzen Dolomite and Portella Dolomite, and an intermediate carbonate-siliciclastic unit, reflecting increased terrigenous input and storm-influenced deposition (Julian-lowermost Tuvalian shallow-water marlstone and marly limestone of the Tor Formation. Above the drowning unconformity at the top of the Portella Dolomite, Tuvalian well-bedded dolomite with claystone intercalations follows (Carnitza Formation. The latter gradually passes into the uppermost Tuvalian–lowermost Rhaetian bedded dolomite with chert and slump breccias, deposited on a slope and/or at the toe-of-slope (Bača Dolomite. Finally, basinal thin-bedded bituminous limestone and marlstone of Rhaetian age follow (Frauenkogel Formation. The upper part of the Frauenkogel Formation contains meter-scale platform-derived limestone blocks, which are signs of platform progradation. The Tarvisio Basin may have extended as far as the present Santo Stefano di Cadore area, representing a notable paleogeographic unit at the western Neotethys margin.

  11. Hydrochemistry (major and trace elements of Lake Malawi (Nyasa, Tanzanian Northern Basin: local versus global considerations

    Directory of Open Access Journals (Sweden)

    P. Branchu

    2010-07-01

    Full Text Available This paper presents the first inventory of dissolved minor and trace element (F, Al, Fe, Mn, Ba, Cd, Cr, Cu, Pb, Mo, Bi, Sr, Zn concentrations in Lake Malawi, the second largest African lake. Sampling was carried out during 1993 dry season in the northern part of the lake. Trace metal concentrations were measured, together with Ca, Mg, Na, K, Cl, SO4, Alkalinity and Si, along three profiles in the lake northern extremity, in five tributaries and two on-land hydrothermal springs. Water profiles show similar elemental distributions and concentrations that are influenced by lake physical-chemical stratification. Stratification, assessed using temperature, conductivity, Si and Mn profiles, is characterised by two boundaries: the thermocline (70–90 m and the oxicline (150–190 m. Elemental water concentrations are discussed using simple covariance analyse. Epilimnetic concentrations and distribution are also influenced by atmospheric deposition and river diving. Comparison of dissolved concentrations for potentially polluting elements with World Health Organisation Guidelines and those reported for other East African lakes shows that this reservoir is uncontaminated despite an increasing human stress. Major element behaviour is assessed through a 3 boxes model. In this model Cl and K are conservative elements whereas Si is removed from the solution by diatom productivity and sedimentation. Ca, Na, Mg and alkalinity show low reactivity. Evaporation is one of the controlling factors of lake element concentration that superimposes on the watershed control. Hydrothermal activity, not evidenced in the lake, controls the chemistry of one of the main northern tributary. Chemical comparison between Northern rivers and other tributaries characterises the geographical and geological specificity of studied northern watershed. Moreover the lake annual chemical budget shows that northern watershed generates the main elemental input to the lake

  12. National Account Energy Alliance Final Report for the Basin Electric Project at Northern Border Pipeline Company's Compressor Station #7, North Dakota

    Energy Technology Data Exchange (ETDEWEB)

    Sweetzer, Richard [Exergy Partners Corp.; Leslie, Neil [Gas Technology Institute

    2008-02-01

    A field research test and verification project was conducted at the recovered energy generation plant at Northern Border Pipeline Company Compressor Station #7 (CS#7) near St. Anthony. Recovered energy generation plant equipment was supplied and installed by ORMAT Technologies, Inc. Basin Electric is purchasing the electricity under a purchase power agreement with an ORMAT subsidiary, which owns and operates the plant.

  13. The northern and central Appalachian basin coal region -- The Upper Freeport and Pond Creek coal bed assessments

    Energy Technology Data Exchange (ETDEWEB)

    Ruppert, L.; Tewalt, S.; Bragg, L.; Wallack, R.; Freeman, P.; Tully, J.

    1999-07-01

    The Upper Freeport and Pond Creek coal beds are two of six coal beds being assessed by the US Geological Survey (USGS) in the northern and central Appalachian basin coal region. The coal resource assessments were designed to provide up-to-date, concise data on the location, quantity, and quality of US coals for Federal agencies, the public, industry and academia. Assessment products are fully digital and include original and remaining resource estimates; maps depicting areal extent, mined areas, geologic structure contour, isopach, overburden thickness, ash yield, sulfur content, calorific value, and selected trace-element contents; and public domain geochemical and stratigraphic databases. The assessment methodology and a few results are presented.

  14. Existing concepts of the formation of the Northern Czech lignite basin

    Energy Technology Data Exchange (ETDEWEB)

    Nurnik, S.

    1982-01-01

    In the Myocene period, the area of sediment accumulation occupied three times more area than the region of the basin's denudation. The Krushnyye Mountains and Czech Midland did not yet exist as orographic units. These morphostructures arose in the Pleistocene epoch. Both morphostructures are currently considered to be an integral part of the large fold.

  15. Late Quaternary faulting on the Manas and Hutubi reverse faults in the northern foreland basin of Tian Shan, China

    Science.gov (United States)

    Gong, Zhijun; Li, Sheng-Hua; Li, Bo

    2015-08-01

    The Tian Shan Range lies in the actively deforming part of the India-Asia collision zone. In the northern foreland basin of Tian Shan, the strata were intensively deformed by Cenozoic folding and faulting. Slip rate studies along these faults are important for understanding the dynamics of crustal deformation and evaluating the seismic hazards in the region. Two reverse faults (the Manas and Hutubi faults) in the northern foreland basin were investigated. Due to past faulting events along these faults, the terrace treads along the Manas River were ruptured, forming fault scarps several meters in height. Loess deposits were trapped and preserved at the surface ruptures along these scarps. The thickness of the trapped loess is dependent on the size of the ruptures. The minimum and maximum ages of these scarps are constrained by dating the loess preserved at the surface ruptures and the terrace treads, respectively, using the quartz optically stimulated luminescence (OSL) dating technique. Our dating results suggest that the loess trapped at the ruptures was deposited from the early to mid-Holocene at the Hutubi Fault, and from the mid- to late-Holocene at the Manas Fault. The vertical displacements of the faults were evaluated by measuring the topographic profiles across the investigated fault scarps using the differential global position system (DGPS). Our results suggest that, during the late Quaternary in the studied region, the vertical slip rates of the Manas Fault were between ˜ 0.74 mm /yr and ˜ 1.6 mm /yr, while the Hutubi Fault had a much lower vertical slip rate between ˜ 0.34 mm /yr and ˜ 0.40 mm /yr. The tectonic implications of our results are discussed.

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

    Directory of Open Access Journals (Sweden)

    JOSÉ M. GUERRA-GARCÍA

    2001-12-01

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

  17. What drives basin scale spatial variability of snowpack properties in northern Colorado?

    Science.gov (United States)

    Sexstone, G. A.; Fassnacht, S. R.

    2014-03-01

    This study uses a combination of field measurements and Natural Resource Conservation Service (NRCS) operational snow data to understand the drivers of snow density and snow water equivalent (SWE) variability at the basin scale (100s to 1000s km2). Historic snow course snowpack density observations were analyzed within a multiple linear regression snow density model to estimate SWE directly from snow depth measurements. Snow surveys were completed on or about 1 April 2011 and 2012 and combined with NRCS operational measurements to investigate the spatial variability of SWE near peak snow accumulation. Bivariate relations and multiple linear regression models were developed to understand the relation of snow density and SWE with terrain variables (derived using a geographic information system (GIS)). Snow density variability was best explained by day of year, snow depth, UTM Easting, and elevation. Calculation of SWE directly from snow depth measurement using the snow density model has strong statistical performance, and model validation suggests the model is transferable to independent data within the bounds of the original data set. This pathway of estimating SWE directly from snow depth measurement is useful when evaluating snowpack properties at the basin scale, where many time-consuming measurements of SWE are often not feasible. A comparison with a previously developed snow density model shows that calibrating a snow density model to a specific basin can provide improvement of SWE estimation at this scale, and should be considered for future basin scale analyses. During both water year (WY) 2011 and 2012, elevation and location (UTM Easting and/or UTM Northing) were the most important SWE model variables, suggesting that orographic precipitation and storm track patterns are likely driving basin scale SWE variability. Terrain curvature was also shown to be an important variable, but to a lesser extent at the scale of interest.

  18. Characteristics of high arsenic groundwater in Hetao Basin, Inner Mongolia, northern China

    Institute of Scientific and Technical Information of China (English)

    YangChun Zhu; XueYong Zhao; Min Chen; YongQing Luo; Xin Zhou

    2015-01-01

    It is well known that the Hetao Basin is one of the most seriously arsenic-affected groundwater areas in China. In order to understand the characteristics of high arsenic (As) groundwater in the Basin, a brief overview of arsenic in groundwater follows. High arsenic in the Basin commonly occurs in shallow groundwater and the total arsenic concentrations range from 0.58 to 572 µg/L (average 99.73 µg/L), exceeding the maximum mandated value of 10 µg/L for drinking water in China;As(Ш) is the predominant species. The regional distribution pattern of arsenic in the groundwater increases from south/southeast to north/northwest. Hangjinhouqi and Wuyuan counties are considered as the most seriously affected areas, with high incidences of endemic arsenicosic diseases in the Hetao Basin. High groundwater arsenic correlates with the increase of well depth. Previous studies proposed that groundwater arsenic in the Basin is mainly originated from desorption of some natural solid materials in the sediments, under reducing condition. Generally, reducing condition is believed to be the primary factor for arsenic releasing from the sediment to groundwater in the region. Under inorganic or bacterial processes, Fe2O3 changes to FeS and arsenic adsorbed to Fe(OH)3 dissolves into groundwater, and As(V) is re-duced to As(Ш). Besides, reducing environments, groundwater hydraulic gradients, organic matter, pH, evapotranspiration, and soil texture are presumed to be the predominant factors that control arsenic mobilization.

  19. Relación de aguas superficiales y subterráneas en el área del lago Chungará y lagunas de Cotacotani, norte de Chile: un estudio isotópico Relation of surface and underground waters in Chungará and Cotacotani lake districts, northern Chile: an isotopic study

    Directory of Open Access Journals (Sweden)

    Christian Herrera

    2006-07-01

    Full Text Available El lago Chungará y las lagunas de Cotacotani corresponden a cuerpos de aguas superficiales localizados al noroeste de la Cuenca del Lauca, en el Altiplano del norte de Chile. Todas las aguas superficiales y subterráneas tienen una salinidad baja a moderada con conductividades eléctricas variables entre 48,7 y 3090 μS/cm. Los lagos están conectados a acuíferos situados en los flancos de los edificios volcánicos próximos, así como en los depósitos de brechas de avalancha del volcán Parinacota. Las composiciones isotópicas de δ18O y δD y su relación con las concentraciones de cloruro de las aguas del lago Chungará, lagunas de Cotacotani, manantiales afluentes y del río Chungará, demuestran que: a. las aguas del lago Chungará presentan una composición química e isotópica homogénea tanto en la horizontal como en la vertical, lo que indica una buena mezcla de las aguas en el lago; b. una parte importante de la recarga hídrica que alimenta las lagunas de Cotacotani procede de aguas del lago Chungará, canalizada a través de un flujo lateral subterráneo y c. el agua subterránea que da origen a los manantiales de la zona tiene su recarga principal en las precipitaciones que se registran durante los meses de primavera-verano (octubre-marzo. Los altos contenidos de tritio (³H medidos en las aguas de los manantiales del sector indican que existe una recarga actual (durante los últimos decenios al sistema acuífero. La aplicación de modelos de parámetro agregado para la interpretación del tiempo de residencia del agua en el acuífero indica que el modelo de flujo de pistón es el que mejor se ajusta a las características isotópicas de estas aguas subterráneasLake Chungará and Cotacotani lake districts are surface water bodies located to the northwest of Lauca Basin in the northern Chilean Altiplano. Surface and underground waters show low to moderate saline content and an electrical conductivity in the range of 48.7 to

  20. Unroofing around Qaidam Basin of northern Tibet at 30 Ma:constraints from 40Ar/39Ar and FT thermochronology on granitoids

    Institute of Scientific and Technical Information of China (English)

    王非; 罗清华; 李齐; 万京林; 郑德文; 王二七

    2002-01-01

    An 40Ar/39Ar and fission track thermochronological study has been carried out on three suites of granitoids collected along the northern and southern edges of the Qaidam Basin to better constrain the mechanisms accommodating the India-Asia collision around the Qaidam Basin (northern Tibet), in order to understand the evolution of the entire deformation area. Mica and K-feldspar have been analyzed and the cooling histories of the latter have been modeled. The cooling histories based upon K-feldspar modeling and fission track ages show that samples simultaneously recorded an important cooling event (7.5-10.7℃/Ma) around 30 Ma, which is thought to reflect an increase of denudation rate related to the tectonic activity in this area associated with uplift suggesting significant crustal thickening starting around 30 Ma in this area. The estimated sedimentation rate in the Qaidam Basin, the propagation rate along the Altyn Tagh fault and field observations support this deduction.

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

    Directory of Open Access Journals (Sweden)

    Cristian Bulboa

    2006-05-01

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

  2. The importance of diverse data types to calibrate a watershed model of the Trout Lake Basin, Northern Wisconsin, USA

    Science.gov (United States)

    Hunt, Randall J.; Feinstein, Daniel T.; Pint, Christine D.; Anderson, Mary P.

    2006-04-01

    As part of the USGS Water, Energy, and Biogeochemical Budgets project and the NSF Long-Term Ecological Research work, a parameter estimation code was used to calibrate a deterministic groundwater flow model of the Trout Lake Basin in northern Wisconsin. Observations included traditional calibration targets (head, lake stage, and baseflow observations) as well as unconventional targets such as groundwater flows to and from lakes, depth of a lake water plume, and time of travel. The unconventional data types were important for parameter estimation convergence and allowed the development of a more detailed parameterization capable of resolving model objectives with well-constrained parameter values. Independent estimates of groundwater inflow to lakes were most important for constraining lakebed leakance and the depth of the lake water plume was important for determining hydraulic conductivity and conceptual aquifer layering. The most important target overall, however, was a conventional regional baseflow target that led to correct distribution of flow between sub-basins and the regional system during model calibration. The use of an automated parameter estimation code: (1) facilitated the calibration process by providing a quantitative assessment of the model's ability to match disparate observed data types; and (2) allowed assessment of the influence of observed targets on the calibration process. The model calibration required the use of a 'universal' parameter estimation code in order to include all types of observations in the objective function. The methods described in this paper help address issues of watershed complexity and non-uniqueness common to deterministic watershed models.

  3. Seismic imaging and analysis of source and migration within an integrated hydrocarbon system study: Northern Gulf of Mexico Basin

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Oliver P.; Hood, Kenneth C.; Harrison, Stanley C. [Exxon Exploration Co., Houston, TX (United States); Wenger, Lloyd M. [Exxon Production Research Co., Houston, TX (United States)

    1995-12-31

    The sources for hydrocarbons in young Tertiary reservoirs of the offshore Gulf of Mexico have been enigmatic in the past due to the lack of source rock penetration in offshore drilling. Exxon formed a multidisciplinary team to address source, maturation, and migration in the northern Gulf of Mexico. The study was initiated in a pilot area east of the Mississippi River Delta where the complete hydrocarbon system can be seismically imaged, then expanded to the west across much of the shelf and slope. Hydrocarbons from seeps and reservoirs were geochemically characterized across the entire northern Gulf of Mexico Basin, and direct oil to source rock correlations were made both offshore (in pilot area) and onshore. Modern 2-D and 3-D seismic was used to develop a geologic framework and to map potential offshore source intervals. The major sources identified offshore are centered on the Eocene, Turonian, Tithonian, and Oxfordian, and correspond to second-order sequence stratigraphic transgressions. (author). 1 fig., 1 tab

  4. Deformación frágil de los depósitos neógenos de la cuenca de Navidad (Cordillera de la Costa, 34°S, Chile central Brittle deformation of the Neogene deposits of the Navidad Basin (Coastal Cordillera, 34°S, central Chile

    Directory of Open Access Journals (Sweden)

    Alain Lavenu

    2005-07-01

    Full Text Available En la cuenca neógena de Navidad, situada en la Cordillera de la Costa de Chile central (~34°S, se identificaron una serie de deformaciones frágiles que fueron generadas durante el Mioceno Tardío y el Plioceno. A partir del análisis numérico de planos de microfallas y sus estrías, se determinaron las direcciones principales de los esfuerzos producidos por diversos eventos tectónicos extensionales y compresivos. Los resultados obtenidos en la cuenca de Navidad permiten concluir que durante el Mioceno Tardío-Plioceno Temprano se produjo una extensión con dirección desconocida. Posteriormente, una deformación extensional, de dirección aproximada este-oeste, afecta a esta zona durante todo el Plioceno. Durante esta época se produce un corto pulso tectónico compresivo de dirección este oeste. A pesar de este evento compresivo la cuenca marina de Navidad se desarrolló esencialmente en un ambiente tectónico extensional durante todo el NeógenoIn the Neogene Navidad Basin, located in the Coastal Range of central Chile (34°S, a series of brittle deformations generated during the Late Miocene and Pliocene, were observed. Based on the numerical analysis of microfault planes and their slickensides, the main stress directions, caused by various extensional and compressive tectonic events, were determined. Results obtained in the Navidad Basin indicate that an extension of unknown direction occurred during the Late Miocene-Early Pliocene. Thereafter, extensional deformation orientated approximately east-west, affected this zone during the whole of the Pliocene. During this epoch a short east-west compressive pulse occurred. In spite of this compressive event, the marine Navidad Basin developed essentially in an extensional tectonic regime during the entire Neogene

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Directory of Open Access Journals (Sweden)

    MARÍA TERESA ALBERDI

    2007-06-01

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

  8. CLIMATE CHANGE IN NORTHERN AFRICA: TOWARDS A RETURN OF RAINFALL ON THE SOUTHERN MEDITERRANEAN BASIN

    OpenAIRE

    NOUACEUR ZEINEDDINE; Laignel, B.; TURKI IMEN; JEMAI HIBA

    2014-01-01

    To determine to what extent climate change affects the rainfall recorded on the southern Mediterranean basin, a trend analysis is proposed. This study is based on the chronological graphic method of processing information (MGCTI) of type "Matrice Bertin". Results show an extreme variability of the precipitations and a severe drought, especially for Morocco, observed since 1970s. Finally, a gradual return to humid conditions is observed from the beginning of the 2000s in Algeria and Tunisia an...

  9. Effects of precipitation and potential evaporation on actual evapotranspiration over the Laohahe basin, northern China

    OpenAIRE

    Y. LIU; L Ren; X. Yang; M. Ma; Yuan, F.; Jiang, S.

    2015-01-01

    Problems associated with water scarcity are facing new challenges under the climate change. As one of main consumptions in water cycle on the Earth, evapotranspiration plays a crucial role in regional water budget. In this paper, we employ two methods, i.e. hydrological sensitivity analysis and hydrological model simulation, to investigate the effect of climate variability and climatic change on actual evapotranspiration (Ea) within the Laohahe basin during 1964–2009. Calibr...

  10. Chronostatigraphic basin framework for Palaeoproterozoic rocks (1730-1575 Ma) in northern Australia and implications of base-metal mineralisation

    International Nuclear Information System (INIS)

    The new chronostratigraphic subdivision for Palaeoproterozoic rocks of northern Australia provides an improved framework for future resource exploration. The nine supersequence boundaries identified in the ca 1730-1575Ma Calvert and Isa Superbasins enable the timing of major tectonic events and their stratigraphic response to be better understood. Third- and 4th-order sequence boundaries facilitate the determination of stratigraphic architecture, ultimately providing the necessary information for constraining the flow of fluids in these basins. SHRIMP zircon ages are essential for determining the magnitude of depositional hiatuses at supersequence and some sequence boundaries, and together with palaeomagnetic data provide independent age constraints for the sequence interpretations. Pb/Pb model ages for the world class Broken Hill, Mt Isa, McArthur River and Century Zn Pb Ag deposits coincide with tectonic events recorded at the Gun, Loretta, River Supersequence boundaries and the superbasin boundary formed during closure of the Isa Superbasin during D2 at Mt Isa. The coincidence of a Pb/Pb model age for Broken Hill with an apparent polar wander path inflection at the Gun Supersequence boundary indicates that the regional chronostratigraphic basin framework developed for northern Australia is applicable to rocks of similar age elsewhere in Australia. Furthermore, if the ultimate cause of these inflections is interplate stress, the basin framework should be globally applicable. Hand-held spectrometers provide an efficient and cost-effective method for collecting gamma-ray data from outcrops. The resulting gamma-ray curves permit more accurate correlation with subsurface stratigraphies and together with facies information facilitate the identification of stratigraphic sequences and their bounding stratal surfaces, the essential building blocks of regional chronostratigraphic correlations. Contrary to general belief most of the sections measured in this study preserve

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

    Directory of Open Access Journals (Sweden)

    Renato Molina

    2012-09-01

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

  12. CLIMATE CHANGE IN NORTHERN AFRICA: TOWARDS A RETURN OF RAINFALL ON THE SOUTHERN MEDITERRANEAN BASIN

    Directory of Open Access Journals (Sweden)

    NOUACEUR ZEINEDDINE

    2014-03-01

    Full Text Available To determine to what extent climate change affects the rainfall recorded on the southern Mediterranean basin, a trend analysis is proposed. This study is based on the chronological graphic method of processing information (MGCTI of type "Matrice Bertin". Results show an extreme variability of the precipitations and a severe drought, especially for Morocco, observed since 1970s. Finally, a gradual return to humid conditions is observed from the beginning of the 2000s in Algeria and Tunisia and since 2008 in Morocco. This new trend is also confirmed by recent results provided by agricultural data of 2011/2012 and 2012/2013.

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

    Directory of Open Access Journals (Sweden)

    Fernando Riveros B.

    2003-04-01

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

  14. Hydrogeochemistry of high iodine groundwater: a case study at the Datong Basin, northern China.

    Science.gov (United States)

    Li, Junxia; Wang, Yanxin; Xie, Xianjun; Zhang, Liping; Guo, Wei

    2013-04-01

    High iodine concentrations in groundwater have seldom been reported and there have been few systematic studies on high iodine groundwater worldwide. To better understand the sources and processes responsible for iodine enrichment in the groundwater of the Datong Basin, the hydrochemical characteristics of groundwater and geochemical features of aquifer sediments were studied. High iodine groundwater mainly occurs in the center of the Datong Basin with iodine concentrations ranging between 3.31 and 1890 μg L(-1). Most samples with iodine concentrations higher than 500 μg L(-1) are from wells with depths between 75 and 120 m. High pH and a reducing environment are favorable for iodine enrichment in the groundwater, with iodide as the dominant species that accounts for 63.2-99.3% of the total iodine. Sediment samples from a borehole specifically drilled for this study contain 0.18-1.46 mg kg(-1) iodine that is moderately correlated with total organic carbon (TOC). The results of sequential extraction experiments show that iodine is mostly bound to iron oxyhydroxides and organic matter in the sediments. The mobilization processes of iodine are proposed to include reductive dissolution of iron oxyhydroxides and transformations among iodide, iodate and organic iodine driven by microbial activities under alkaline and reducing conditions. PMID:23478640

  15. Snow cover dynamics and hydrological regime of the Hunza River basin, Karakoram Range, Northern Pakistan

    Directory of Open Access Journals (Sweden)

    A. A. Tahir

    2011-07-01

    Full Text Available A major proportion of flow in the Indus River is contributed by its snow- and glacier-fed river catchments situated in the Himalaya, Karakoram and Hindukush ranges. It is therefore essential to understand the cryosphere dynamics in this area for water resource management. The MODIS MOD10A2 remote-sensing database of snow cover products from March 2000 to December 2009 was selected to analyse the snow cover changes in the Hunza River basin (the snow- and glacier-fed sub-catchment of the Indus River. A database of daily flows for the Hunza River at Dainyor Bridge over a period of 40 yr and climate data (precipitation and temperature for 10 yr from three meteorological stations within the catchment was made available to investigate the hydrological regime in the area. Analysis of remotely sensed cryosphere (snow and ice cover data during the last decade (2000–2009 suggest a rather slight expansion of cryosphere in the area in contrast to most of the regions in the world where glaciers are melting rapidly. This increase in snow cover may be the result of an increase in winter precipitation caused by westerly circulation. The impact of global warming is not effective because a large part of the basin area lies under high altitudes where the temperature remains negative throughout most of the year.

  16. INNOVATIVE METHODOLOGY FOR DETECTION OF FRACTURE-CONTROLLED SWEET SPOTS IN THE NORTHERN APPALACHIAN BASIN

    Energy Technology Data Exchange (ETDEWEB)

    Robert Jacobi; John Fountain

    2001-02-28

    In the structure task, we completed a N-S transect east of Seneca Lake that indicated a N-striking fault near the southeastern shore of Seneca Lake, and also indicated NE and ENE-trending FIDs and faults north of Valois. The orientation and existence of the NE-striking FIDs and faults are thought to be controlled by basement faults, rather than thrust ramps above the Salina salt controlled only by a far-field Alleghanian stress field. Structure contour maps based on well log analyses have been constructed but not interpreted. Soil gas data displayed a number of ethane-charged soil gas ''spikes'' on a N-S transect from Ovid south to near Valois. The soil gas team found a larger number of spikes in the northern half of the survey, suggesting more open fractures (and faults) in the northern half of the survey. Seismic data has been purchased and reprocessed. Several grabens observed in the Trenton reflector are consistent with surface structure, soil gas, and aeromagnetic anomalies. The aeromagnetic survey is completed and the data is processed. Prominent magnetic anomalies suggest that faults in the Precambrian basement are located beneath regions where grabens in the Trenton are located.

  17. Tectonics and paleogeography of the Marajó Basin, northern Brazil

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    JOÃO B. S. COSTA

    2002-09-01

    Full Text Available The Marajó Basin area presents geologic and geomorphologic features chiefly due to the Mesozoic extension and post-Miocene neotectonics. The extension event with an Early and a Late Cretaceous phases originated four sub-basins that constitutes the Marajó Basin, with a thick continental clastic sequence showing marine influence. NW and NNW normal faults and NE and ENE strike-slip faults controlled the basin geometry. The extension, related to the Equatorial Atlantic opening, propagated into the continent along crustal weakness zones of the Precambrian Tumucumaque, Amapá and Araguaia orogenic belts. The neotectonic event is a strike-slip regime which developed transtensional basins filled in by Upper Tertiary shallow marine (Pirabas Formation and transitional sequences (Barreiras Group, followed by Quaternary fluvial deposits and transitional sequences derived from the Amazon and Tocantins rivers and the Marajoara estuary. The current landscape has a typical estuarine morphology. The coast morphology presents sea-cliffs on transitional Upper Tertiary sequences, while inwards dominate hills sustained by Mid-Pleistocene lateritic crust, with a flat erosive surface at 70 m. In the eastern Marajó Island several generations of paleochannels associated with fluvial-estuarine sequences are recognized, while a fluvial-marine plain is widespread on its western side.A área da Bacia do Marajó apresenta feições geológicas e geomorfológicas devidas principamente à distensão Mesozóica e à neotectônica pós-miocênica. O evento de distensão, com fases do Cretáceo Inferior e Superior, originou quatro sub-bacias que contituem a Bacia do Marajó, com uma espessa seqüência clástica continental mostrando influência marinha. Falhas normais NW e NNW e direcionais NE e ENE controlaram a geometria da bacia. A distensão, relacionada com a abertura do Atlântico Equatorial, propagou-se continente adentro ao longo de zonas de fraqueza crustal dos

  18. Spatio-temporal snow cover change and hydrological characteristics of the Astore, Gilgit and Hunza river basins (western Himalayas, Hindukush and Karakoram region) - Northern Pakistan

    Science.gov (United States)

    Tahir, Adnan Ahmad; Chevallier, Pierre; Arnaud, Yves; Lane, Stuart; Terzago, Silvia; Adamowski, Jan Franklin

    2015-04-01

    A large proportion of Pakistan's irrigation water supply is drawn from the Upper Indus River Basin (UIB) situated in the Himalaya-Karakoram-Hindukush (HKH) ranges. More than half of the annual flow in the UIB is contributed by five of its high-altitude snow and glacier-fed sub-basins including the Astore (Western Himalaya - southern part of the UIB), Gilgit (Hindukush - western part of the UIB) and Hunza (Central Karakoram - northern part of the UIB) River basins. Studying the snow cover, its spatio-temporal evolution and the hydrological response of these sub-basins is important so as to better manage water resources. This study compares data from the Astore, Gilgit and Hunza River basins (mean catchment elevation, 4100, 4250 and 4650 m ASL, respectively), obtained using MODIS satellite snow cover images. The hydrological regime of these sub-catchments was analyzed using hydrological and climate data available at different altitudes from the basin areas. The results suggest that the UIB is a region undergoing a stable or slightly increasing trend of snow cover in the southern (Western Himalayas), western (Hindukush) and northern (Central Karakoram) parts. Discharge from the UIB is a combination of snow and glacier melt with rainfall-runoff in the southern part, but snow and glacier melt is dominant in the northern and western parts of the catchment. Despite similar snow cover trends (stable or slightly increasing), different river flow trends (increasing in Astore and Gilgit, decreasing in Hunza) suggest that a sub-catchment level study of the UIB is needed to understand thoroughly its hydrological behavior for better flood forecasting and water resources management and to quantify how the system is being forced by changing climate.

  19. Sedimentological and geochronological evidences of anthropogenic impacts on river basins in the Northern Latium coastal area (Italy)

    Science.gov (United States)

    Piazzolla, Daniele; Paladini de Mendoza, Francesco; Scanu, Sergio; Marcelli, Marco

    2015-04-01

    In this work we aimed to compare sedimentological and geochronological data from three sediment core samples (MIG50, MRT50, and GRT50) taken in the Northern Latium (Italy) coastal area, at -50 m depth, to data regarding rainfall, river flows and the land use in the three most important hydrographic basins (Mignone, Marta and Fiora) and in the coastal area. Different trends of sediment mass accumulation rate (MAR) are detected in the three cores: a strongly increasing trend was identified in MIG50 and MRT50 cores while GRT50 doesn't show significant variation. Data from the sedimentological analysis of GRT50 core identify a progressive decrease in the sandy component, which declined from about 30% to the current level of 7% over the last 36 years, while MRT50 and MIG50 cores (mainly composed by pelitic fraction > 95%) showed slight variations of textural ratio between silt and clay. According to the general decrease of pluviometric trend observed in Italy, related to teleconnection pattern tendency (NAO), the statistical analysis of rain identified significative decrease only in the Fiora river basin, whereas in the other two locations the decrease was not as significant. Regarding the Fiora river flow, a significative decreasing trend of average flow is detected, while the flood regime remained unaffected over the past 30 years. The analysis of the land use shows that the human activities are increased of 6-10% over the available time steps (1990 - 2006) in Fiora and Mignone river basins, while the Marta river basin has a strong human impact since 1990 highligting more than 80% of artificial soil covering. The largest variation is observed on the Fiora basin (10%) where the antrhopic activities have expanded to an area of about 85 Km2. Moreover, in the last ten years a large beach nourishment in 2004 (570000 m3) and dredging activities in the early second half of 2000s (1000000 m3 moved) were performed in Marina di Tarquinia beach and in front of the Torrevaldaliga

  20. Two new species of Pseudancistrus (Siluriformes, Loricariidae from the Amazon basin, northern Brazil

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    Gabriel da Costa e Silva

    2015-02-01

    Full Text Available Two new species of Pseudancistrus, a genus diagnosed by non-evertible cheek plates and hypertrophied odontodes along the snout margin, are described from two drainages of the Brazilian Shield: P. kayabi from the rio Teles Pires (rio Tapajós basin and P. asurini from the rio Xingu. The new species are distinguished from congeners (P. barbatus, P. corantijniensis, P. depressus, P. nigrescens, P. reus, and P. zawadzkii by the coloration pattern. Pseudancistrus kayabi has dark bars on the dorsal and caudal fins which are similar to that of P. reus from the Caroní River, Venezuela. Pseudancistrus asurini is unique among Pseudancistrus in having whitish tips of the dorsal and caudal fins in juveniles to medium-sized adults.

  1. Shelf-edge sedimentary systems off Rio de Janeiro State, northern Santos basin-Brazil

    Science.gov (United States)

    Maia, R. M. C.; Dos Reis, A. T.; Gorini, C.; Silva, C. G.; Rabineau, M.; Granjeon, D.

    2012-04-01

    elements provide a hint at a prevailing subsidence regime and effective sediment supply into the basin that clearly contrast with the conveyed idea of a sediment-starved and tectonic stable shelf. They naturally raise questions about the nature and origin of sediment supply, since no significant point siliciclastic fluvial source flows directly into the shelf. Stemming from that, we are forced to speculate about: (A) the role of neotectonic movements involving the Serra do Mar coastal mountain ranges to potentially source clastic influx into the basin during the Quaternary, or about the real importance of secondary drainage basins debouching today; and (B) the mechanical nature of a supposed subsidence during the Pliocene and the Quaternary time span (overloading ? sediment compaction ? thermal cooling ?). The interpretation of industrial seismic lines can provide the answers of many of these questions. The next step of this work is to make a stratigraphy model of the sedimentary systems of Santos basin to understand how the ancient creation of accommodation space can influence the recent sedimentary architecture and how is the change in sedimentary influx and the sedimentary records of different orders of cyclicity.

  2. Organic geochemical characterisation of shallow marine Cretaceous formations from Yola Sub-basin, Northern Benue Trough, NE Nigeria

    Science.gov (United States)

    Sarki Yandoka, Babangida M.; Abdullah, Wan Hasiah; Abubakar, M. B.; Hakimi, Mohammed Hail; Jauro, Aliyu; Adegoke, Adebanji Kayode

    2016-05-01

    The shallow marine shales of the Cretaceous formations namely Yolde, Dukul, Jessu, Sekuliye and Numanha ranging in age from Cenomanian to Coniacian within the Yola Sub-basin in the Northern Benue Trough, northeastern Nigeria were analysed to provide an overview on their hydrocarbon generation potential. This study is based on pyrolysis analysis, total organic carbon content (TOC), extractable organic matter (EOM), biomarker distributions and measured vitrinite reflectance. The present-day TOC contents range between 0.24 and 0.71 wt. % and Hydrogen Index (HI) values between 8.7 and 113 mg HC/g TOC with Type III/IV kerogens. Based on the present-day kerogen typing, the shale sediments are expected to generate mainly gas. Biomarker compositions indicates deposition in a marine environment under suboxic conditions with prevalent contribution of aquatic organic matter and a significant amount of terrigenous organic matter input. Organic matter that is dominated by marine components contains kerogens of Type II and Type II-III. This study shows that the organic matter has been affected by volcanic intrusion and consequently, have reached post-mature stage of oil generation. These higher thermal maturities levels are consistent with the vitrinite reflectance ranging from 0.85 to 2.35 Ro % and high Tmax (440-508 °C) values as supported by biomarker maturity ratios. Based on this study, a high prospect for major gas and minor oil generation potential is anticipated from the shallow marine Cretaceous formations from Yola Sub-basin.

  3. Late Pleistocene shortening rate on the northern margin of the Yanqi Basin, southeastern Tian Shan, NW China

    Science.gov (United States)

    Huang, Wei-liang; Yang, Xiao-ping; Li, An; Pierce, Ian K. D.; Thompson, Jessica A.; Angster, Stephen J.; Zhang, Ling

    2015-11-01

    How strain is distributed and partitioned on individual faults and folds on the margins of intermontane basins remains poorly understood. The Haermodun (Ha) anticline, located along the northern margin of the intermontane Yanqi Basin on the southeastern flank of the Tian Shan, preserves flights of passively deformed alluvial terraces. These terraces cross the active anticline and can be used to constrain local crustal shortening and uplift rates. Geologic and geomorphic mapping, in conjunction with high-resolution dGPS topographic surveys, reveal that the terrace surfaces are perpendicular to the fold's strike, and display increased rotation with age, implying that the anticline has grown by progressive limb rotation. Combined with the open sinusoidal curve model and excess area method, we calculated uplift and shortening values for each terrace since abandonment. Using the published exposure ages of each terrace, we found the vertical uplift rate gradually decreased from ∼0.43 to ∼0.11 mm/a, whereas the shortening rate remained constant at ∼0.3 mm/a since the anticline began to grow. A fresh fault scarp, 0.4 ± 0.1 m high, is visible along the southern portion of the Ha anticline, and is interpreted to be the most recent evidence of seismic activity. Using an estimated rupture area and the length of the fresh offset created by this earthquake, we estimate that the main thrust underlying the Ha anticline has generated moderate (M < 7) earthquakes in the past. The shortening rates of the Ha anticline from geomorphology agree with current GPS measurements cover-over the fold, and highlight the importance of determining slip rates for individual faults in order to resolve patterns of strain distribution across intermontane belts.

  4. Occurrence, behavior and distribution of high levels of uranium in shallow groundwater at Datong basin, northern China

    International Nuclear Information System (INIS)

    Geochemical investigations of uranium (U) occurrence in the environments were conducted at Datong basin of northern China. The results suggest that U contents were generally 22+) species is dominant and strongly adsorbed onto iron (hydro)xides, while it would be preferentially complexed with carbonate in the alkaline groundwater, forming highly soluble uranyl-carbonate complexes at Datong. Under reducing conditions, uranous (U(IV)) species is ready to precipitate or bind to organic matter, therefore having a low mobility. At the study area, high U groundwater (> 30 μg/L) occurs at the alluvial plains due to intermediate redox and enhanced alkaline conditions. The abnormally high levels of U in groundwater (> 100 μg/L) are locally found at the west alluvial plains. By contrast, U co-precipitation with secondary carbonate minerals like Ca2UO2(CO3)3 in the dominant Ca–Mg–Na–HCO3 type groundwater may prevail at the east alluvial plains. Besides, bedrocks such as Carboniferous and Permian sedimentary rocks, especially the coal-bearing strata which have higher U contents at the west mountain areas may also account for the abnormally high levels of U in groundwater. - Highlights: • High U groundwater occurs at the alluvial plains of Datong basin. • Redox state, complexation and adsorption are responsible for U enrichment. • Carboniferous and Permian sedimentary rocks have higher U contents at Datong. • Uranyl is preferentially complexed with carbonate in groundwater. • U in the aquifer sediments may be primarily associated with carnotite

  5. ATTENUATION OF SEISMIC WAVES IN THE LITHOSPHERE OF THE NORTHERN PART OF THE BASIN AND RANGE PROVINCE

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    А. А. Dobrynina

    2015-09-01

    Full Text Available This paper presents results of the study of attenuation of seismic waves in the lithosphere and upper mantle of the northern part of the Basin and Range Province (BRP (Fig. 1. In this study, the coda-wave method [Aki, Chouet, 1975] is applied to process data collected in the seismic experiment conducted in 1988–1989, PASSCAL Basin and Range Passive Seismic Experiment [Owens, Randall, 1989], including records of 66 earthquakes and explosions (Mb=1.1–5.0 which occurred in BRP (Fig. 2.The effective seismic quality factor by the coda is calculated using the single-backscattering model [Aki, Chouet, 1975]. The QC values are calculated for 18 values of the lapse time window W from 10 to 95 sec with the step of 5 sec at six (6 central frequencies (0.3, 0.75, 1.5, 3.0, 6.0, and 12.0 Hz. In total, 7776 individual measurements of QC were done. It is observed that the quality factor QC is strongly dependent on the frequency and the lapse time window W: QC increases from 12±6 to 359±17 for the central frequencies of 0.3 and 12.0 Hz when the lapse time window is W=10 sec and from 87±6 to 1177±87 for the same frequencies when W=95 sec (Fig. 6. On the basis of the QС values obtained for all the lapse time windows W empirical relationships of quality factors and frequencies are calculated according to [Mitchell, 1981], and values of quality factor Q0 at reference frequency f0 (f0=1 Hz and frequency parameter n (which is close to 1 and varies depending on the heterogeneity of the medium [Aki, 1981] are obtained. In this study, Q0 varies from 60±8 to 222±17, the frequency parameter ranges from 0.57±0.04 to 0.84±0.05, and the attenuation coefficient δ varies from 0.015 to 0.004 km–1, depending on W (Fig. 8; similar values of attenuation parameters are typical of regions with high tectonic activity [Mak et al., 2004].In the single-backscattering model, the dependence of the attenuation parameters from the lapse time window can be explained in terms

  6. Seismic reflection-based evidence of a transfer zone between the Wagner and Consag basins: implications for defining the structural geometry of the northern Gulf of California

    Science.gov (United States)

    González-Escobar, Mario; Suárez-Vidal, Francisco; Hernández-Pérez, José Antonio; Martín-Barajas, Arturo

    2010-12-01

    This study examines the structural characteristics of the northern Gulf of California by processing and interpreting ca. 415 km of two-dimensional multi-channel seismic reflection lines (data property of Petróleos Mexicanos PEMEX) collected in the vicinity of the border between the Wagner and Consag basins. The two basins appear to be a link between the Delfín Superior Basin to the south, and the Cerro Prieto Basin to the north in the Mexicali-Imperial Valley along the Pacific-North America plate boundary. The seismic data are consistent with existing knowledge of four main structures (master faults) in the region, i.e., the Percebo, Santa María, Consag Sur, and Wagner Sur faults. The Wagner and Consag basins are delimited to the east by the Wagner Sur Fault, and to the west by the Consag Sur Fault. The Percebo Fault borders the western margin of the modern Wagner Basin depocenter, and is oriented N10°W, dipping (on average) ˜40° to the northeast. The trace of the Santa María Fault located in the Wagner Basin strikes N19°W, dipping ˜40° to the west. The Consag Sur Fault is oriented N14°W, and dips ˜42° to the east over a distance of 21 km. To the east of the study area, the Wagner Sur Fault almost parallels the Consag Sur Fault over a distance of ˜86 km, and is oriented N10°W with an average dip of 59° to the east. Moreover, the data provide new evidence that the Wagner Fault is discontinuous between the two basins, and that its structure is more complex than previously reported. A structural high separates the northern Consag Basin from the southern Wagner Basin, comprising several secondary faults oriented NE oblique to the main faults of N-S direction. These could represent a zone of accommodation, or transfer zone, where extension could be transferred from the Wagner to the Consag Basin, or vice versa. This area shows no acoustic basement and/or intrusive body, which is consistent with existing gravimetric and magnetic data for the region.

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

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    Walter Sielfeld K

    1995-01-01

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

  8. Did Oligocene crustal thickening precede basin development in northern Thailand? A geochronological reassessment of Doi Inthanon and Doi Suthep

    Science.gov (United States)

    Gardiner, Nicholas J.; Roberts, Nick M. W.; Morley, Christopher K.; Searle, Michael P.; Whitehouse, Martin J.

    2016-01-01

    The Doi Inthanon and Doi Suthep metamorphic core complexes in northern Thailand are comprised of amphibolite-grade migmatitic gneisses mantled by lower-grade mylonites and metasedimentary sequences, thought to represent Cordilleran-style core complexes exhumed through the mobilization of a low-angle detachment fault. Previous studies have interpreted two metamorphic events (Late Triassic and Late Cretaceous), followed by ductile extension between the late Eocene and late Oligocene, a model which infers movement on the detachment at ca. 40 Ma, and which culminates in a rapid unroofing of the complexes in the early Miocene. The Chiang Mai Basin, the largest such Cenozoic Basin in the region, lies immediately to the east. Its development is related to the extension observed at Doi Inthanon and Doi Suthep, however it is not definitively dated, and models for its development have difficulty reconciling Miocene cooling ages with Eocene detachment movement. Here we present new in-situ LA-ICP-MS and SIMS U-Pb age data of zircon and monazite grains from gneiss and leucogranite samples taken from Doi Inthanon and Doi Suthep. Our new zircon data exhibit an older age range of 221-210 Ma, with younger ages of ca. 72 Ma, and 32-26 Ma. Our monazite data imply an older age cluster at 83-67 Ma, and a younger age cluster of 34-24 Ma. While our data support the view of Indosinian basement being reworked in the Cretaceous, they also indicate a late Eocene-Oligocene tectonothermal event, resulting in prograde metamorphism and anatexis. We suggest that this later event is related to localized transpressional thickening associated with sinistral movement on the Mae Ping Fault, coupled with thickening at the restraining bend of the Mae Yuan Fault to the immediate west of Doi Inthanon. Further, this upper Oligocene age limit from our zircon and monazite data would imply a younger Miocene constraint on movement of the detachment, which, when combined with the previously recorded Miocene

  9. Benthic macro red alga:A new possible bio-precursor of Jurassic mudstone source rocks in the northern Qaidam Basin,northwestern China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Whether benthic macroalga can be an important type of bio-precursor of source rocks is a contentious issue in source-rock studies,and has not been well understood.This paper represents a case study of Jurassic mudstone source rocks from the northern Qaidam Basin,northwestern China,in which the benthic macro red algae were recognized for the first time based on combined organic petrological and biomarker works.We found not only cystocarps in the algae,representative of rhodophyta,but also diahopanes,which are diagnostic biomarkers of such algae.Thus,as many reservoired oils in the northern Qaidam Basin contain abundant diahopanes,it may indicate that the red algae have contributed to hydrocarbon accumulation.This was confirmed by integrated geological and geochemical analyses.Hence,this study provides new evidence for macroalga-generated hydrocarbons.

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

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    Francisco Tapia C

    2009-09-01

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

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

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    MADELEINE LAMBOROT

    2001-03-01

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

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

    Directory of Open Access Journals (Sweden)

    Marianela Medina

    2007-05-01

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

  13. Growth of the Zagros Fold-Thrust Belt and Foreland Basin, Northern Iraq, Kurdistan

    Science.gov (United States)

    Koshnaw, Renas; Horton, Brian; Stockli, Daniel; Barber, Douglas; Ghalib, Hafidh; Dara, Rebwar

    2016-04-01

    The Zagros orogenic belt in the Middle Eastern segment of the Alpine-Himalayan system is among the youngest seismically active continental collision zones on Earth. However, due to diachronous and incremental collision, the precise ages and kinematics of shortening and deposition remain poorly understood. The Kurdistan region of the Zagros fold-thrust belt and foreland basin contains well-preserved Neogene wedge-top and foredeep deposits that include clastic nonmarine fill of the Upper Fars, Lower Bakhtiari, and Upper Bakhtiari Formations. These deposits record significant information about orogenic growth, fold-thrust dynamics, and advance of the deformation front. Thermochronologic and geochronologic data from thrust sheets and stratigraphic archives combined with local earthquake data provide a unique opportunity to address the linkages between surface and subsurface geologic relationships. This research seeks to constrain the timing and geometry of exhumation and deformation by addressing two key questions: (1) Did the northwestern Zagros fold-thrust belt evolve from initial thin-skinned shortening to later thick-skinned deformation or vice-versa? (2) Did the fold-thrust belt advance steadily under critical/supercritical wedge conditions involving in-sequence thrusting or propagate intermittently under subcritical conditions with out-of-sequence deformation? From north to south, apatite (U-Th)/He ages from the Main Zagros Thrust, the Mountain Front Flexure (MFF), and additional frontal thrusts suggest rapid exhumation by ~10 Ma, ~5 Ma, and ~8 Ma respectively. Field observations and seismic sections indicate progressive tilting and development of growth strata within the Lower Bakhtiari Formation adjacent to the frontal thrusts and within the Upper Bakhtiari Formation near the MFF. In the Kurdistan region of Iraq, a regional balanced cross section constrained by new thermochronometric results, proprietary seismic reflection profiles, and earthquake hypocenters

  14. Quantification of effects of climate variations and human activities on runoff by a monthly water balance model: A case study of the Chaobai River basin in northern China

    OpenAIRE

    Wang, G; Xia, J.; J. Che

    2009-01-01

    The Chaobai River basin in northern China consists of two major tributaries, the Chao River and Bai River. Monthly observations of precipitation, streamfiow, and panevaporation data are available for 35 years (1961-1966 and 1973-2001). Using the annual time series of the observed streamfiow, one break point at 1979 is detected and is adopted to divide the data set into two study periods, the "before" and "after" periods marking the onset of significant anthropogenic alteration of the flow (re...

  15. Middle to late Cenozoic basin evolution in the western Alborz Mountains: Implications for the onset of collisional deformation in northern Iran

    OpenAIRE

    Guest, Bernard; Horton, Brian K.; Axen, Gary J.; Hassanzadeh, Jamshid; MCINTOSH, William C.

    2007-01-01

    Oligocene-Miocene strata preserved in synclinal outcrop belts of the western Alborz Mountains record the onset of Arabia-Eurasia collision-related deformation in northern Iran. Two stratigraphic intervals, informally named the Gand Ab and Narijan units, represent a former basin system that existed in the Alborz. The Gand Ab unit is composed of marine lagoonal mudstones, fluvial and alluvial-fan clastic rocks, fossiliferous Rupelian to Burdigalian marine carbonates, and basalt flows yielding ^...

  16. An investigation of the genus Mesacanthus (Chordata: Acanthodii) from the Orcadian Basin and Midland Valley areas of Northern and Central Scotland using traditional morphometrics

    OpenAIRE

    Baron, Matthew G.

    2015-01-01

    Mesacanthus is a common and speciose genus of acanthodian fish from Lower Old Red Sandstone and Middle Old Red Sandstone assemblages (representing the Lower Devonian and Middle Devonian respectively) and is well represented in many palaeoichthyology collections in the UK. Based upon descriptions given during the 19th century, specimens of the genus Mesacanthus from the Orcadian Basin and Midland Valley areas of Northern and Central Scotland have historically been referred to a number of diffe...

  17. Hydrogeochemistry of co-occurring geogenic arsenic, fluoride and iodine in groundwater at Datong Basin, northern China.

    Science.gov (United States)

    Pi, Kunfu; Wang, Yanxin; Xie, Xianjun; Su, Chunli; Ma, Teng; Li, Junxia; Liu, Yaqing

    2015-12-30

    Abnormal levels of co-occurring arsenic (As), fluorine (F) and iodine (I) in groundwater at Datong Basin, northern China are geochemically unique. Hydrochemical, (18)O and (2)H characteristics of groundwater were analyzed to elucidate their mobilization processes. Aqueous As, F and I ranged from 5.6 to 2680 μg/L, 0.40 to 3.32 mg/L and 10.1 to 186 μg/L, respectively. High As, F and I groundwater was characterized by moderately alkaline, high HCO3(-), Fe(II), HS(-) and DOC concentrations with H3AsO3, F(-) and I(-) as the dominant species. The plots of δ(18)O values and Cl/Br ratios versus Cl(-) concentration demonstrate build-up of more oxidizing conditions and precipitation of carbonate minerals induced by vertical recharge and intensive evaporation facilitate As retention to Fe (hydr) oxides, but enhance F and I mobilization from host minerals. Under reducing conditions, As and I can be simultaneously released via reductive dissolution of Fe (hydr) oxides and reduction of As(V) and I(V) while F migration may be retarded due to effects of dissolution-precipitation equilibria between carbonate minerals and fluorite. With the prevalence of sulfate-reducing condition and lowering of HCO3(-) concentration, As and I may be sequestered by Fe(II) sulfides and F is retained to fluorite and on clay mineral surfaces. PMID:26282220

  18. Simulation experiment on hydrocarbon generating potential of various source rocks on the northern margin of the Qaidam Basin, Qinghai, China

    Institute of Scientific and Technical Information of China (English)

    LI Xin; WANG Dongliang; LIU Baoquan; REN Chunling; GUO Jianying; SU Xuefeng; WANG Jian

    2008-01-01

    The northern margin of the Qaidam Basin is one of the main oil-gas exploration areas in western China, where source rocks are composed mostly of Middle and Lower Jurassic dark mud shale, carbargillite and coal. A large number of subsurface and outcrop samples differing in lithology with different types of organic matter were selected for resource evaluation, research and calculation. And among them, 13 samples were used for simulation experiment on hydrocarbon generating potential of various source rocks. At first, two kinds of heating modes were compared through simulation experiment, including single temperature-step heating and continual heating. Perhaps, the process of hydrocarbon generation and expulsion occurred naturally between a close system and an open system. In addition, the first heating mode was convenient, and all its reaction products were involved in the whole thermal evolution, and the final simulation experimental results were basically in consistency with the natural evolution trend. Therefore, the first heating mode was adopted and the hydrocarbon yield of every sample was worked out. According to the type and lithology of organic matter and the hydrocarbon yield of samples for simulation experiment, hydrocarbon generation and expulsion mode with three kinds of lithology and five types of source rock has been established to provide the basis for hydrocarbon generation evaluation, research and resource calculation.

  19. Quantification and multivariate analysis of water erosion in the Mediterranean region. A case study of the Isser basin. northern Algeria

    Science.gov (United States)

    Zeggane, Houari; Boutoutaou, Djamel

    2016-07-01

    In the Mediterranean region, the specifisity of erosion stems from a particularly contrasted climate, drought, and from summer and autumn severe thunderstorms. The process of erosion generates substantial loss of soil and affects any kind of crop. The adopted approach aims to establish regression models in order to highlight the relationship between solid and liquid flows at four measurement stations in the Isser catchement area, northern Ageria. The Power Model seems to explain this relationship. The quantification and temporal analysis of solid matter transport showed that the rates of erosion are high along the study area. The annual mean solid matter transport for the whole basin is about 2 200 t/km2.year, of which the main part is recorded in autumn during peak flows. The different factors involved in the process of water erosion are determined in advance in order to establish a model between the predictand variable, which is the specific erosion, and other predictors. Besides, a functional relationship has been highlighted between water erosion and the mean slope, the drainage density and the lithology index.

  20. Seismicity in the Raton Basin of Southern Colorado and Northern New Mexico, USA, as Recorded by a Local Array

    Science.gov (United States)

    Macartney, H.

    2013-12-01

    Microseismic events (Basin of southern Colorado and northern New Mexico, USA, over a period of 18 months following the occurrence of a 5.3 magnitude event near Trinidad CO in August, 2011. Micro-seismicity was observed in the region, concentrated in six clusters at depths of 6-12 km below the surface, deep in the basement, and 4-10 km below zones used for fluid disposal from an overlying coalbed methane natural gas field. Clusters are separated from disposal zones by large aseismic intervals. The clusters are mixed in character; both planar and elongate amorphous swarms, some continually active and some as short-lived bursts, with larger initial events tending to occur deeper and smaller after-shocks propagating upward and away from the nucleating events. Magnitudes range between 0 and 3, with the vast majority being less than 1.5M. Most of the clusters have no disposal wells above and no seismic activity was correlated with changes in fluid disposal. No seismicity was detected from hydraulic fracturing operations.

  1. Stable isotope record of Eemian seasonal temperature from MIS 5e tufa stromatolite; Somme Basin, Northern France

    Directory of Open Access Journals (Sweden)

    J. Dabkowski

    2013-03-01

    Full Text Available In many modern to sub-fossil deposits tufa formations, very well crystallised deposits called stromatolites are preserved. These are often strongly laminated deposits, the laminae linked to seasonal climatic and environmental variations. Where found in fossil tufas such deposits have huge potential as high resolution archives of Pleistocene climate. One of the first investigations of this type has been performed on a 2.5 cm-radius stromatolite from the Eemian sequence of Caours (Somme Basin, Northern France, where precise observations in thin section have been combined with intra-lamina δ18O and δ13C analyses. Independent interpretations of petrographical and geochemical data are strongly coherent and demonstrate a clear seasonal signal. Moreover, as δ18O is temperature dependent, we have quantified likely maximum water temperature variations between summer and winter at Caours. A small mismatch between the δ18O derived temperature values and the typical modern range is observed, which may reflect a real difference between modern and Eemian temperature seasonality. This study supports previous investigations performed on a laminated tufa from central Greece and clearly confirms the potential of tufa stromatolites as records of seasonal climatic information and for the quantification of riverine water temperature variations.

  2. Thick-skinned Contractional Salt Structures in the Kuqa Depression, the Northern Tarim Basin: Constraints from Physical Experiments

    Institute of Scientific and Technical Information of China (English)

    YU Yixin; TANG Liangjie; YANG Wenjing; JIN Wenzheng; PENG Gengxin; LEI Ganglin

    2008-01-01

    Thick-skinned contractional salt structures are widely developed in the western Kuqa depression, northern Tarim basin. To understand the mechanisms that govern the development of these structures, physical experiments are conducted and the results show that they are largely governed by the activities of basement faults and the forming of paleo-uplifts and basement slopes. The model materials in this study are dry sand, vaseline and plasticene (or hard foam), simulating the suprasalt, salt, and subsalt layers respectively. The experiments show that, due to the activities of basement faults and the forming of the paleo-uplifts, salt bodies usually accumulate and thicken significantly on the middle top of the paleo-uplifts which are constrained by the pre-exiting boundary faults. The development of large-scale thrust faults and salt nappes is favored by the basement slops with larger dips. The experiments also conclude that differential structural deformation could occur between the subsalt and suprasalt layers because of the presence of salt layers. Their geometries and the locations of structural highs are different, despite of the great similarities in the uplifted areas. The pierced salt diapir is not observed in the experiments, which indicates that the contractional shortening does not effectively accelerate the development of the salt diapir.

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

    Directory of Open Access Journals (Sweden)

    JOSE MIGUEL FARIÑA

    2000-03-01

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

  4. Structural framework and its evolution in Chasang area of Qiangtang Basin in northern Tibetan

    Institute of Scientific and Technical Information of China (English)

    刘池洋; 杨兴科; 任战利; 赖绍聪; 陈刚; 赵红格; 魏永佩; 郑孟林; 王成善

    2001-01-01

    Through comprehensive research on the various geophysical and geological data acquired recently, we consider that the Chasang area in the western uplift of Qiangtang is a huge south-dipping block which is overlapped by several east-west trending blocks rather than a simple and palaeo-doming existing for a long time. The structural and geophysical features of the area, which only alone limited between Shuanghu and Rongma districts, are of no regional significance. Their development is closely related with the approximately south-north trending transform faults developed during the Mesozoic era on the east and west sides of the area and their later continuous movement. The compressing, overlapping and uplifting of the Chasang area began at the stage of reversing of the Qiangtang Basin during the Lower Cretaceous, which is in direct relation with Bangonghu-Dingqing limited ocean’s closure and the convergence of the neighboring blocks. The compression and overlapping of the area have further developed and re

  5. 26Al/10Be burial dating of Xujiayao-Houjiayao site in Nihewan Basin, northern China.

    Directory of Open Access Journals (Sweden)

    Hua Tu

    Full Text Available The Xujiayao-Houjiayao site in Nihewan Basin is among the most important Paleolithic sites in China for having provided a rich collection of hominin and mammalian fossils and lithic artifacts. Based on biostratigraphical correlation and exploratory results from a variety of dating methods, the site has been widely accepted as early Upper Pleistocene in time. However, more recent paleomagnetic analyses assigned a much older age of ∼500 ka (thousand years. This paper reports the application of 26Al/10Be burial dating as an independent check. Two quartz samples from a lower cultural horizon give a weighted mean age of 0.24 ± 0.05 Ma (million years, 1σ. The site is thus younger than 340 ka at 95% confidence, which is at variance with the previous paleomagnetic results. On the other hand, our result suggests an age of older than 140 ka for the site's lower cultural deposits, which is consistent with recent post-infrared infrared stimulated luminescence (pIR-IRSL dating at 160-220 ka.

  6. Late Quaternary evolution of the Rotoaira Basin, northern Tongariro ring plain, New Zealand

    International Nuclear Information System (INIS)

    The last 100,000 yr record of volcaniclastic sedimentation in the Rotoaira Basin reflects the critical role played by tectonic and eruptive activity that led to: (1) the catastrophic emplacement of Te Whaiau Formation (60-55 ka); (2) major episodes of effusive activity (c. 30 ka and c. 15 ka); and (3) syn- and post-eruptive lahar aggradation on the shores of Lake Rotoaira. Stratigraphic unconformities, fluvial and aeolian reworking, and subsequent volcanogenic sedimentation indicate that climate change driven periods of erosion contributed significantly to the evolution of the landscape during the late Quaternary. Waters that accumulated in a newly expanded graben formed Lake Rotoaira. An attempt to core through the sediments on the lake's floor revealed a >6.5 m thick mantling of Taupo ignimbrite, restricting chronostratigraphic sampling to the last 1.85 ka. Lake Rotoaira pollen profiles record: (1) the destruction of the indigenous forest by the Taupo ignimbrite eruption; (2) the following period of vegetation recovery (c. 300 yr); and (3) periods of human occupation of the lakeshores (bracken spores and Pinus pollen) in the younger sediments. Coarse sand generated by the 1995-96 tephra-producing Ruapehu eruptions also contributed to the recent lake sedimentation. (author). 59 refs., 9 figs., 1 tab

  7. Mesozoic deformation in the Chaoshan Depression of the Pearl River Mouth Basin, northern South China Sea

    Science.gov (United States)

    Zhang, Jiangyang; Sun, Zhen; Zhang, Yunfan; Li, Fucheng

    2016-05-01

    Newly collected, high resolution multi-beam sonar data are combined with previous bathymetry data to produce an improved bathymetric map of Shatsky Rise oceanic plateau. Bathymetry data show that two massifs within Shatsky Rise are immense central volcanoes with gentle flank slopes declining from a central summit. Tamu Massif is a slightly elongated, dome-like volcanic edifice; Ori Massif is square shaped and smaller in area. Several down-to-basin normal faults are observed on the western flank of the massifs but they do not parallel the magnetic lineations, indicating that these faults are probably not related to spreading ridge faulting. Moreover, the faults are observed only on one side of the massifs, which is contrary to expectations from a mechanism of differential subsidence around the massif center. Multi-beam data show many small secondary cones with different shapes and sizes that are widely-distributed on Shatsky Rise massifs, which imply small late-stage magma sources scattered across the surface of the volcanoes in the form of lava flows or explosive volcanism. Erosional channels occur on the flanks of Shatsky Rise volcanoes due to mass wasting and display evidence of down-slope sediment movement. These channels are likely formed by sediments spalling off the edges of summit sediment cap.

  8. Genetic Relationship between Natural Gas Dispersal Zone and Uranium Accumulation in the Northern Ordos Basin, China

    Institute of Scientific and Technical Information of China (English)

    GAN Huajun; XIAO Xianming; LU Yongchao; JIN Yongbin; TIAN Hui; LIU Dehan

    2007-01-01

    The Ordos Basin is well-known for the coexistence of oil, natural gas, coal and uranium. However, there has been little research to discuss the genetic relationship between them. In this paper, a case study of the Zaohuohao area in Dongsheng, Inner Mongolia, China, is conducted to investigate the genetic relationship between the natural gas and the uranium accumulation. Fluid inclusion data from the uranium-bearing sandstone samples indicate that the fluid inclusions formed in a gas-water transition zone. Using the homogeneous temperatures of aqueous inclusions coeval with hydrocarbonbearing inclusions, combined with the buried history and paleo-temperature data, the gas-water transition zone reached the area at about 110 Ma. On the basis of this, the contents of Uranium (U)and Total Organic Carbon (TOC) of the samples were analyzed, and there was no obvious relation between them. With regard to the available data from both publications and this study, it is found that the U mineralization has a spatiotemporal accordance with the gas-water dispersal zone. Thus, it is believed that the natural gas in the gas-water zone is an effective reducer to the U-bearing ground water abundant in oxygen, which is the main factor to U accumulation. This result can be used as the reference to the U mines predicting and prospecting.

  9. Winter and spring mixing depths affect the trophic status and composition of phytoplankton in the northern meromictic basin of Lake Lugano

    Directory of Open Access Journals (Sweden)

    Marco SIMONA

    2003-08-01

    Full Text Available The trophic state of Lake Lugano is still too high to be acceptable, despite extensive recovery measures undertaken in recent decades which have resulted in a reduction of the external phosphorus load to the deepest of the lake's basins (northern basin; Zmax=286 m to fairly acceptable values. Since meromixis was established in the middle of last century, the deep hypolimnion of the northern basin (the layer between ca 100 m and the bottom has contained high quantities of nutrients (especially phosphorus which are a major potential source of internal load. When there are particularly strong winter mixing events, a portion of this phosphorus reserve is redistributed along the upper water column (0-100 m. The impact of meteo-climatic conditions on the plankton biocenosis were analysed using data collected in the northern basin (Gandria station during the three-year period 1998-2000. The phytoplankton composition, which is typical of eutrophicated waters, shows marked interannual variations, also depending on the degree of mixing of the waters at the start of the vegetative period. Though there is no steady pattern of typical dominant species / master species in the lake, there is a seasonal succession characterised by a marked development of diatoms in spring, and a predominance of chlorophyceans and cyanobacteria in summer and autumn. Under present conditions, the mechanisms of internal replenishment of nutrients towards the euphotic layer, due to the phenomena of late winter and spring mixing, constitute a significant source of nutrients for the spring and summer growth of phytoplankton. On the other hand, pronounced mixing phenomena, like those occurring in the two-year period 1999-2000, can reduce the hypolimnetic nutrient reserves and cause a decrease in the trophic potential of the basin, contrasting with an increase in algal biomass in the euphotic zone.

  10. Rayleigh-wave ellipticity and shallow structure in sedimentary basins: the Po Plain (northern Italy)

    Science.gov (United States)

    Berbellini, A.; Morelli, A.; Ferreira, A. M. G.

    2015-12-01

    The amplitude ratio between horizontal and vertical components of Rayleigh waves (also known as ellipticity) is in principle uniquely sensitive to local earth structure beneath each recording station. Rayleigh wave ellipticity is mostly influenced by the shallowest layers, so it can be effectively used to infer the structure of the uppermost crust, with particular relevance for sedimentary environments. We implement an automatic method to measure Rayleigh wave ellipticity, and extensively apply it to teleseismic records from the northern part of Italy, for a period range between 10s and 130s. As expected, no appreciable correlation with epicenter distance or azimuth can be seen, but rather a strong correlation with local structure: generally high horizontal to vertical amplitude ratios are seen in sedimentary settings, with respect to Alpine and Apenninic crystalline-rock terrains. We verify that shortest usable period may be limited by very low shear-wave velocity in shallow sediments, when the assumed retrograde elliptical particle motion polarisation for the fundamental mode breaks off. The highly non-linear sensitivity of frequency-dependent ellipticity curves can then be inverted using a direct search method to infer shear wave velocity profiles below stations. By comparing our results with local a priori geological information we show that robust information can indeed be retrieved.

  11. Preliminary Paleomagnetic Results From Tertiary Rocks of Sedimentary Basins in Northern Vietnam and Tectonic Implications

    Science.gov (United States)

    Zhao, X.; Liu, Z.; Le, K.; Zhao, Y.; Hoang, V.; Phan, D.

    2013-12-01

    The South China Sea (SCS) is a classical representative of western Pacific marginal seas and contains records of Cenozoic tectonic events of SE Asia. The SCS has been at the center stage of many first-order tectonic and paleoclimatic events since the Mesozoic. One clear way to evaluate the relationship between tectonic uplift and climate is to study the resulting changes in marginal sea strata. To this end, we will conduct an integrated paleomagnetic and stratigraphic investigation on Tertiary strata from Phu Tho and Yen Bai provinces, northern Vietnam to help understand the causal linkages among geological and tectonic events and their consequences related to the SCS evolution. We will collect paleomagnetic samples at sections where the most continuous, complete, and best preserved Eocene-Miocene successions. Standard paleomagnetic field tests, such as the fold, reversal, and conglomerate tests will be used to determine the relative age of the magnetization. In addition to detailed thermal and alternating field demagnetization and analysis, selected samples will also be subjected to several rock magnetic analyses to identify magnetic carriers in the rocks. In particular, the hysteresis parameters Jrs/Js and Hcr /Hc ratios will enable us to apply techniques for detecting low-temperature remagnetization of sedimentary rocks. Preliminary finding of this ongoing project will be presented.

  12. Understanding the Hydrogeology of Raya Valley Basin, Northern Ethopia Using Stablee Isotopes of Water

    International Nuclear Information System (INIS)

    The Raya valley is located in the northern part of Ethiopia. The study area is connected to the Ethiopian rift system and bounded by the Ethiopian plateau to the west and Cherecher Mountain to the east. The study area is characterized by its semiarid climate. In order to investigate isotopic characteristics of different water bodies and groundwater recharge, water samples were collected in the summer rainy season and analysed for stable isotopes of oxygen and hydrogen by a laser based liquid water isotope analyser. Most of the groundwater samples are plotted just below the LMWL, which indicates that the origin is meteoric water and affected by secondary evaporation. There are highly depleted water samples in the eastern side of the study area, which could be attributed to the existence of palaeowater. Groundwater is mainly recharged by rain water and intermittent rivers. Open water bodies (the lake Ashenge and Gerjale swamp area) show enrichment due to high rate of evaporation. Isotopically the flood water in the highland aarea is depleted as a result of high rate of rainfall, high humidity and low rate of evaporation. (author)

  13. Structural architecture and tectonic evolution of the Maghara inverted basin, Northern Sinai, Egypt

    Science.gov (United States)

    Moustafa, Adel R.

    2014-05-01

    Large NE-SW oriented asymmetric inversion anticlines bounded on their southeastern sides by reverse faults affect the exposed Mesozoic and Cenozoic sedimentary rocks of the Maghara area (northern Sinai). Seismic data indicate an earlier Jurassic rifting phase and surface structures indicate Late Cretaceous-Early Tertiary inversion phase. The geometry of the early extensional fault system clearly affected the sense of slip of the inverted faults and the geometry of the inversion anticlines. Rift-parallel fault segments were reactivated by reverse slip whereas rift-oblique fault segments were reactivated as oblique-slip faults or lateral/oblique ramps. New syn-inversion faults include two short conjugate strike-slip sets dissecting the forelimbs of inversion anticlines and the inverted faults as well as a set of transverse normal faults dissecting the backlimbs. Small anticline-syncline fold pairs ornamenting the steep flanks of the inversion anticlines are located at the transfer zones between en echelon segments of the inverted faults.

  14. Characterization of submarine canyon bathymetries in northern Ionian Sea, Italy, using sediment geochemical variation induced by transportation distance and basin depth

    Science.gov (United States)

    Francesco, Perri; Tohru, Ohta; Salvatore, Critelli

    2015-07-01

    Geochemical data of marine mud sediments collected from the Esaro, Neto and Corigliano canyons in the northern Ionian Sea (southern Italy) were investigated in order to characterize canyon bathymetry types. Mud sample compositions analyzed by the principal component analysis (PCA) provided useful information for the morphology of the depositional area of the northern Ionian Sea. The use of sediment geochemical data as well as transportation distance and depth as input variables for PCA enabled the extraction of following latent variables: basin depth (PC1), sedimentation rate (PC2) and transportation distance (PC3). Based on these results, we further developed geochemical indices that can estimate basin depth (F1), sedimentation rate (F2) and transportation distance (F3); these functions can be solely calculated from the elemental concentration data of the mud samples. Since these F1, F2 and F3 functions are mathematically independent variables, they facilitate more precise characterization of individual canyon types. That is, the Esaro Canyon is regarded as a sediment-starved deep canyon characterized by a single source area; the Neto Canyon can be seen as a deeply sloped submarine apron system and sediments are mainly supplied by the sediment gravity flows; the Corigliano Canyon is characterized by multiple sources and moderately sloped system, whose sediments disperse mainly by traction currents. These interpretations are concordant with the basin bathymetry of the studied area. Therefore, F1, F2 and F3 functions might be applicable to any oceanic basins.

  15. Assessment of River Habitat Quality in the Hai River Basin, Northern China

    Directory of Open Access Journals (Sweden)

    Yuekui Ding

    2015-09-01

    Full Text Available We applied a river habitat quality (RHQ assessment method to the Hai River Basin (HRB; an important economic centre in China; to obtain baseline information for water quality improvement; river rehabilitation; and watershed management. The results of the assessment showed that the river habitat in the HRB is seriously degraded. Specifically; 42.41% of the sites; accounting for a river length of 3.31 × 104 km; were designated poor and bad. Habitat in the plain areas is seriously deteriorated; and nearly 50% of the sites; accounting for a river length of 1.65 × 104 km; had either poor or bad habitats. River habitat degradation was attributable to the limited width of the riparian zone (≤5 m; lower coverage of riparian vegetation (≤40%; artificial land use patterns (public and industrial land; frequent occurrence of farming on the river banks and high volumes of solid waste (nearly 10 m3; single flow channels; and rare aquatic plants (≤1 category. At the regional scale; intensive artificial land use types caused by urbanization had a significant impact on the RHQ in the HRB. RHQ was significantly and negatively correlated with farmland (r = 1.000; p < 0.01 and urban land (r = 0.998; p < 0.05; and was significantly and positively correlated with grassland and woodland (r = 1.000; p < 0.01. Intensive artificial land use; created through urbanization processes; has led to a loss of the riparian zone and its native vegetation; and has disrupted the lateral connectivity of the rivers. The degradation of the already essentially black rivers is exacerbated by poor longitudinal connectivity (index of connectivity is 2.08–16.56; caused by reservoirs and sluices. For river habitat rehabilitation to be successful; land use patterns need to be changed and reservoirs and sluices will have to be regulated.

  16. Assessment of River Habitat Quality in the Hai River Basin, Northern China.

    Science.gov (United States)

    Ding, Yuekui; Shan, Baoqing; Zhao, Yu

    2015-09-01

    We applied a river habitat quality (RHQ) assessment method to the Hai River Basin (HRB); an important economic centre in China; to obtain baseline information for water quality improvement; river rehabilitation; and watershed management. The results of the assessment showed that the river habitat in the HRB is seriously degraded. Specifically; 42.41% of the sites; accounting for a river length of 3.31 × 10⁴ km; were designated poor and bad. Habitat in the plain areas is seriously deteriorated; and nearly 50% of the sites; accounting for a river length of 1.65 × 10⁴ km; had either poor or bad habitats. River habitat degradation was attributable to the limited width of the riparian zone (≤5 m); lower coverage of riparian vegetation (≤40%); artificial land use patterns (public and industrial land); frequent occurrence of farming on the river banks and high volumes of solid waste (nearly 10 m³); single flow channels; and rare aquatic plants (≤1 category). At the regional scale; intensive artificial land use types caused by urbanization had a significant impact on the RHQ in the HRB. RHQ was significantly and negatively correlated with farmland (r = 1.000; p urban land (r = 0.998; p urbanization processes; has led to a loss of the riparian zone and its native vegetation; and has disrupted the lateral connectivity of the rivers. The degradation of the already essentially black rivers is exacerbated by poor longitudinal connectivity (index of connectivity is 2.08-16.56); caused by reservoirs and sluices. For river habitat rehabilitation to be successful; land use patterns need to be changed and reservoirs and sluices will have to be regulated. PMID:26393628

  17. Subsurface structure and stratigraphy of the northwest end of the Turkana Basin, Northern Kenya Rift, as revealed by magnetotellurics and gravity joint inversion

    Science.gov (United States)

    Abdelfettah, Yassine; Tiercelin, Jean-Jacques; Tarits, Pascal; Hautot, Sophie; Maia, Marcia; Thuo, Peter

    2016-07-01

    In order to understand the subsurface stratigraphy and structure of the northwest end of the Turkana Basin, Northern Kenya Rift, we used 2-D joint inversion of magnetotelluric (MT) and gravity data acquired along 3 profiles perpendicular to the main Murua Rith-Lapur Rift Border Fault. The regional geology is characterized by a basement of Precambrian age overlain by a ≤500-m thick sandstone formation named the Lapur Sandstone of upper Cretaceous-lower Eocene in age, covered by thick rhyolitic and basaltic lavas of late Eocene-middle Miocene age, known as the "Turkana Volcanics". Final interpretation of the resistivity and density models, until 5 km depth, obtained by the joint inversion approach confirms the previous general knowledge about the half-graben geometry of the northern part of the Turkana Basin. The main Murua Rith-Lapur Rift Border Fault is well identified by both gravity and MT. At least, two other important secondary faults without surface expression are also identified. A new small half-graben basin, named the Kachoda Basin, parallel to the main Turkana Basin and filled by 1.5 km of sediments, has been also characterized. This study also highlights strong thickness variations of the three main geological units that could be expected in the subsurface of the Turkana Basin. For example, the sedimentary Nachukui and Kibish Formations reach up to >3 km in thickness at the eastern end of the north and central profiles. Lateral variations of the topography of the Precambrian basement are also evidenced. Conceptual geological models, which result from the combination of the obtained density and resistivity models as well as from geological and reflection seismic data, are proposed. In such an area of intensive and promising oil exploration, these models are essential in terms of identification of reservoirs, source rocks and trapping mechanisms.

  18. Aerosol chemistry above an extended Archipelago of the Eastern Mediterranean basin during strong northern winds

    Directory of Open Access Journals (Sweden)

    E. Athanasopoulou

    2015-03-01

    Full Text Available Detailed aerosol chemical predictions by a carefully designed model system (i.e. PMCAMx, WRF, GEOS-CHEM, along with airborne and ground-based observations, are presented and analyzed over a wide domain covering the Aegean Archipelago. The studied period is ten successive days during the summer of 2011, characterized by the most frequent prevailing wind conditions (Etesian regime. The submicron aerosol load in the lower troposphere above the Archipelago (< 2.2 km altitude is homogenously enriched in sulfate (average modeled and measured submicron sulfate of 5.5 and 5.8 μg m−3, respectively, followed by organics (2.3 and 4.4 μg m−3 and ammonium (1.5 and 1.7 μg m−3. Aerosol concentrations smoothly decline aloft, reaching lower values (< 1 μg m−3 above 4.2 km altitude. Model performance is found good (according the selected evaluation criteria for sulfate, ammonium, chloride, elemental carbon, organic carbon and total PM10 mass concentration, indicating a satisfactory representation of the aerosol chemistry and precursors. Higher model discrepancies are confined to the highest (e.g. peak sulfate values and lowest ends (e.g. nitrate of the airborne aerosol mass size distribution, as well as in airborne organic concentrations (model underestimation around 50%. The latter is most probably related to the intense fire activity upwind the Archipelago (i.e. Balkan area and Black Sea coastline, which is not represented in the current model application. Overall, the model system shows the best agreement with observations under strong northeastern winds over the Archipelago and up to 2.2 km altitude. The activation of the chemical ageing of biogenic particles is suggested to be used for the aerosol chemistry module, when treating organics in a sufficient nitrogen and sulfate-rich environment, such as that over the Aegean basin. More than 70% of the predicted aerosol mass over the Aegean Archipelago during a representative Etesian episode is

  19. RECONNAISSANCE ASSESSMENT OF CO2 SEQUESTRATION POTENTIAL IN THE TRIASSIC AGE RIFT BASIN TREND OF SOUTH CAROLINA, GEORGIA, AND NORTHERN FLORIDA

    Energy Technology Data Exchange (ETDEWEB)

    Blount, G.; Millings, M.

    2011-08-01

    A reconnaissance assessment of the carbon dioxide (CO{sub 2}) sequestration potential within the Triassic age rift trend sediments of South Carolina, Georgia and the northern Florida Rift trend was performed for the Office of Fossil Energy, National Energy Technology Laboratory (NETL). This rift trend also extends into eastern Alabama, and has been termed the South Georgia Rift by previous authors, but is termed the South Carolina, Georgia, northern Florida, and eastern Alabama Rift (SGFAR) trend in this report to better describe the extent of the trend. The objectives of the study were to: (1) integrate all pertinent geologic information (literature reviews, drilling logs, seismic data, etc.) to create an understanding of the structural aspects of the basin trend (basin trend location and configuration, and the thickness of the sedimentary rock fill), (2) estimate the rough CO{sub 2} storage capacity (using conservative inputs), and (3) assess the general viability of the basins as sites of large-scale CO{sub 2} sequestration (determine if additional studies are appropriate). The CO{sub 2} estimates for the trend include South Carolina, Georgia, and northern Florida only. The study determined that the basins within the SGFAR trend have sufficient sedimentary fill to have a large potential storage capacity for CO{sub 2}. The deeper basins appear to have sedimentary fill of over 15,000 feet. Much of this fill is likely to be alluvial and fluvial sedimentary rock with higher porosity and permeability. This report estimates an order of magnitude potential capacity of approximately 137 billion metric tons for supercritical CO{sub 2}. The pore space within the basins represent hundreds of years of potential storage for supercritical CO{sub 2} and CO{sub 2} stored in aqueous form. There are many sources of CO{sub 2} within the region that could use the trend for geologic storage. Thirty one coal fired power plants are located within 100 miles of the deepest portions of

  20. Structure and Stratigraphy of the Rift Basins in the Northern Gulf of California: Results from Analysis of Seismic Reflection and Borehole Data.

    Science.gov (United States)

    Martín, A.; González, M.; Helenes, J.; García, J.; Aragón, M.; Carreño, A.

    2008-12-01

    The northern Gulf of California contains two parallel, north-south trending rift basin systems separated by a basement-high. The interpretation of several exploration wells, and ~4500 km of seismic reflection data from PEMEX (Mexican national oil company) indicate that the tectonically active basins to the west (Wagner- Consag and Upper Delfin basins) may have initiated synchronously with the now abandoned Tiburón- Tepoca-Altar basins to the east in the Sonora margin. In both basin systems the lower sequence (A) is marine mudstone-siltstone, has parallel reflectors and a largely uniform thickness that reaches up to1.5 km, and gradually pinches out toward the lateral margins. This suggests that the unit was deposited prior to their segmentation by transtensional faulting. Marine microfossils from borehole samples from sequence A in the Tiburón and Consag basins indicates middle Miocene (>11.2 Ma) proto-Gulf conditions. Sequence B conformably overlies sequence A, and is characterized by up to 2 km growth strata with a fanning geometry that show a clear genetic relationship to the major transtensional faults that control the segmentation of the two basin systems. Sequence C in the Tiburón and Tepoca basins is comparatively thin (<800 m) and includes several unconformities, but is much less affected by faulting. In contrast, sequence C in the active Wagner, Consag and Upper Delfin basin is a much thicker (up to 2 km) growth sequence with abundant volcanic intrusions. Marked variations in sequence C in the different basin systems clearly demonstrate a major westward shift of deformation and subsidence at this time. The modern depocenter in Wagner-Consag basins is controlled by the Consag and Wagner faults, which trend parallel to the north ~20 km apart, and show opposite normal offset. These two faults merge at an oblique angle (70°-50°, respectively) into the Cerro Prieto transform fault to the north and likely accommodate an important amount of dextral shear. To

  1. The Jurassic-Cretaceous Boundary (Tithonian - Hauterivian) in the Andean Basin of Central Chile: Ammonites, Bio- and Sequence Stratigraphy and Palaeobiogeography

    OpenAIRE

    Salazar Soto, Christian Andrés

    2012-01-01

    Five sections of the Baños del Flaco and Lo Valdés formations in the High Andean Cordillera of Central Chile have been analyzed with regard to sediment, bio- and sequence stratigraphy, ammonite assemblages and palaeobiogeography, in order to reveal the age and depositional facies of the sediment sequence, and to evaluate the age and important bioevents across the Jurassic-Cretaceous boundary. The Baños del Flaco Formation was investigated at Rio Tinguiririca and in the Rio Maitenes valley,...

  2. Determining the source and genetic fingerprint of natural gases using noble gas geochemistry: a northern Appalachian Basin case study

    Science.gov (United States)

    Hunt, Andrew G.; Darrah, Thomas H.; Poreda, Robert J.

    2012-01-01

    Silurian and Devonian natural gas reservoirs present within New York state represent an example of unconventional gas accumulations within the northern Appalachian Basin. These unconventional energy resources, previously thought to be noneconomically viable, have come into play following advances in drilling (i.e., horizontal drilling) and extraction (i.e., hydraulic fracturing) capabilities. Therefore, efforts to understand these and other domestic and global natural gas reserves have recently increased. The suspicion of fugitive mass migration issues within current Appalachian production fields has catalyzed the need to develop a greater understanding of the genetic grouping (source) and migrational history of natural gases in this area. We introduce new noble gas data in the context of published hydrocarbon carbon (C1,C2+) (13C) data to explore the genesis of thermogenic gases in the Appalachian Basin. This study includes natural gases from two distinct genetic groups: group 1, Upper Devonian (Marcellus shale and Canadaway Group) gases generated in situ, characterized by early mature (13C[C1  C2][13C113C2]: –9), isotopically light methane, with low (4He) (average, 1  103 cc/cc) elevated 4He/40Ar and 21Ne/40Ar (where the asterisk denotes excess radiogenic or nucleogenic production beyond the atmospheric ratio), and a variable, atmospherically (air-saturated–water) derived noble gas component; and group 2, a migratory natural gas that emanated from Lower Ordovician source rocks (i.e., most likely, Middle Ordovician Trenton or Black River group) that is currently hosted primarily in Lower Silurian sands (i.e., Medina or Clinton group) characterized by isotopically heavy, mature methane (13C[C1 – C2] [13C113C2]: 3), with high (4He) (average, 1.85  103 cc/cc) 4He/40Ar and 21Ne/40Ar near crustal production levels and elevated crustal noble gas content (enriched 4He,21Ne, 40Ar). Because the release of each crustal noble gas (i.e., He, Ne, Ar

  3. Growth Normal Faulting at the Western Edge of the Metropolitan Taipei Basin since the Last Glacial Maximum, Northern Taiwan

    Directory of Open Access Journals (Sweden)

    Chih-Tung Chen

    2010-01-01

    Full Text Available Growth strata analysis is an useful tool in understanding kinematics and the evolution of active faults as well as the close relationship between sedimentation and tectonics. Here we present the Shanchiao Fault as a case study which is an active normal fault responsible for the formation of the 700-m-thick late Quaternary deposits in Taipei Basin at the northern tip of the Taiwan mountain belt. We compiled a sedimentary record, particularly the depositional facies and their dated ages, at three boreholes (SCF-1, SCF-2 and WK-1, from west to east along the Wuku Profile that traverses the Shanchiao Fault at its central segment. By incorporating the global sea level change curve, we find that thickness changes of sediments and changes of depositional environments in the Wuku area are in a good agreement with a rapid sea level rise since the Last Glacial Maximum (LGM of about 23 ka. Combining depositional facies changes and their ages with their thickness, we are able to introduce a simple back-stripping method to reconstruct the evolution of growing strata across the Shanchiao Fault since the LGM. We then estimate the vertical tectonic slip rate since 23 ka, which exhibits 2.2 mm yr-1 between SCF-2 and WK-1 and 1.1 mm yr-1 between SCF-1 and SCF-2. We also obtain the Holocene tectonic subsidence rate of 2.3 mm yr-1 at WK-1 and 0.9 mm yr-1 at SCF-2 since 8.4 ka. We thus conclude that the fault zone consists of a high-angle main fault to the east between SCF-2 and WK-1 and a western lower-angle branch fault between SCF-1 and SCF-2, resembling a tulip structure developed under sinistral transtensional tectonism. We find that a short period of 600-yr time span in 9 - 8.4 ka shows important tectonic subsidence of 7.4 and 3.3 m for the main and branch fault, respectively, consistent with possible earthquake events proposed by previous studies during that time. A correlation between geomorphology and subsurface geology in the Shanchiao Fault zone shows

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

    International Nuclear Information System (INIS)

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

  5. Extensional Basins in a Convergent Margin: Oligocene-Early Miocene Salar de Atacama and Calama basins, Central Andes

    Science.gov (United States)

    Jordan, T. E.; Mpodozis, C.; Blanco, N.; Pananont, P.; Dávila, F.

    2004-12-01

    The Salar de Atacama Basin (SdAB) is the largest and most persistent sedimentary basin of northern Chile, accumulating nonmarine sediment from Cretaceous to modern times. Its northwestern neighbor, the Calama, was a Cenozoic basin. Although SdAB was in the backarc zone early in the Andean orogeny, both are now forearc basins. Others demonstrated that the basins overlie anomalously cold, strong, and dense crust and lithosphere. We focus on an extensional Oligocene basin stage. Interpretation of the basin-controlling faults is based on seismic reflection studies supported by field relations. The SdAB is limited to the west by the NNE-trending, steeply east-dipping, Paciencia Fault (PF). The PF experienced 5-7 km of down-to-the-east offset during the Oligocene-early Miocene. Syntectonic strata, an arid succession of siliciclastics and evaporites, are asymmetric, with thicknesses of 5000 m and abundant halite adjacent to the PF, and of 1000 m with fine detrital clastic strata 25 km farther east. Relations in conglomeratic growth strata that overlap the PF also demonstrate normal displacement during sediment accumulation. Seismic data reveal that a buried normal fault with 1-1.5 km down-to-the-east displacement limits the western margin of the Oligocene-Miocene Calama siliciclastic basin fill. Regionally, Oligocene-early Miocene margin-parallel strike-slip deformation dominated northwest of the basins, contributing sinistral offset (West Fissure Fault) to the northern segment of the long-lived Domeyko Fault System. The new SdAB and Calama data reveal that a 20,000 km2 domain of extensional basins existed within the dominantly strike-slip region. Even if PF and the fault in the Calama Basin were transtensional, the proportion of extension to strike-slip displacement is much greater in these basins than elsewhere in northern Chile. Further study is required to understand what combination of factors caused this kinematic distinction as well as delayed the onset of CVZ

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

    Directory of Open Access Journals (Sweden)

    Javier González

    2007-07-01

    Full Text Available The Cordón de Lila is located immediately to the south of the Salar de Atacama, in northern Chile. The geology of the Cordón de Lila is characterized by extensive outcrops of Early Paleozoic volcanic and sedimentary rocks (Cordón de Lila Igneous and Sedimentary Complex; CISL that form the 'Arco magmático occidental' (AMO which is intruded by a multiple suite of Middle Ordovician to Lower Silurian granitoids. In this contribution we report the results of a sedimentological and paleontological study of a recently discovered 1,600 m thick marine Ordovician sedimentary sequence (Quebrada Grande Formation which unconformably overlies the CISL. The Quebrada Grande Formation comprises three mayor facies associations. In stratigrafic order, these facies associations are: matrix-supported conglomerates (1, interbedded sandstones and siltstones (2 and clast-supported conglomerates (3. Facies association (1 is interpreted as debris flow deposits accumulated in a proximal marine fan-delta setting while the overlying sandstones and siltstones facies (2 represent open-marine platform deposits. Clast-supported conglomerates (3 are the record of high-energy sedimentary episodes during which coarse sediments reached the distal part of the fan-delta. The detrital fraction of the Quebrada Grande Formation is derived from the erosion of the Cambrian?-Lower Ordovician? CISL volcanic arc, the plutonio roots of the arc and its continental basement. The age of this formation is well constrained by the occurrence of brachiopods (Paralenorthis sp., Monorthis transversa Benedetto, and Mollesella? sp. near the base and graptolites (Tetragraptus sp. and Cryptograptus? sp. towards the middle of the succession. Both brachiopods and graptolites indicate an Arenigian to early Llanvirnian (Darriwilian age. The brachiopod assemblage from Cordón de Lila displays affinities with the Famatina basin fauna of western Argentina. The absence of taxa in common between the AMO and

  7. Patrón de asentamiento durante el periodo Alfarero en la cuenca de Santiago, Chile Central: Una mirada a la escala local Settlement pattern during the early Ceramic period in the Santiago basin, Central Chile: A view at the local level

    Directory of Open Access Journals (Sweden)

    Luis Cornejo

    2012-11-01

    Full Text Available Se presentan y discuten la metodología y los resultados de prospecciones superficiales de alta intensidad realizadas en el extremo meridional de la cuenca de Santiago, poniendo énfasis en una escala de análisis hasta ahora no considerada en la arqueología de Chile Central, que es el estudio sistemático de la localidad. Los resultados muestran que el patrón de asentamiento denota una alta concentración de ocupaciones domésticas del periodo Alfarero temprano, continuadas más tardíamente pero con menor intensidad. Estas ocupaciones resultan estar vinculadas a la disponibilidad en esta localidad de recursos de aguas superficiales y reflejarían una forma de ocupar el espacio definida por unidades domésticas dispersas que en sus cercanías tendrían a otras unidades sociales no necesariamente vinculadas socialmente.This paper presents the methodology and results of intensive surface surveys carried out in the southern Santiago Basin, focused on the locality, a scale of analysis not previously undertaken in archeological studies of Central Chile. The settlement pattern point out to a high concentration of Early Ceramic Period domestic occupations, followed by less intense occupations during the Late Ceramic Period. These occupations were linked to the availability in this locality of surface water resources and reflect a way of occupying space defined by scattered domestic units , in whose vicinity were other domestic units, although not necessarily connected socially.

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

    Directory of Open Access Journals (Sweden)

    Oscar Pablo Diaz

    2015-05-01

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

  9. Identifying hydro-meteorological events from precipitation extremes indices and other sources over northern Namibia, Cuvelai Basin

    Directory of Open Access Journals (Sweden)

    Frans C. Persendt

    2015-02-01

    Full Text Available Worldwide, more than 40% of all natural hazards and about half of all deaths are the result of flood disasters. In northern Namibia flood disasters have increased dramatically over the past half-century, along with associated economic losses and fatalities. There is a growing concern to identify these extreme precipitation events that result in many hydro-meteorological disasters. This study presents an up to date and broad analysis of the trends of hydrometeorological events using extreme daily precipitation indices, daily precipitation data from the Grootfontein rainfall station (1917–present, regionally averaged climatologies from the gauged gridded Climate Research Unit (CRU product, archived disasters by global disaster databases, published disaster events in literature as well as events listed by Mendelsohn, Jarvis and Robertson (2013 for the data-sparse Cuvelai river basin (CRB. The listed events that have many missing data gaps were used to reference and validate results obtained from other sources in this study. A suite of ten climate change extreme precipitation indices derived from daily precipitation data (Grootfontein rainfall station, were calculated and analysed. The results in this study highlighted years that had major hydro-meteorological events during periods where no data are available. Furthermore, the results underlined decrease in both the annual precipitation as well as the annual total wet days of precipitation, whilst it found increases in the longest annual dry spell indicating more extreme dry seasons. These findings can help to improve flood risk management policies by providing timely information on historic hydro-meteorological hazard events that are essential for early warning and forecasting.

  10. Scenarios for shale gas development and their related land use impacts in the Baltic Basin, Northern Poland

    International Nuclear Information System (INIS)

    Scenarios for potential shale gas development were modelled for the Baltic Basin in Northern Poland for the period 2015–2030 using the land allocation model EUCS100. The main aims were to assess the associated land use requirements, conflicts with existing land use, and the influence of legislation on the environmental impact. The factors involved in estimating the suitability for placement of shale gas well pads were analysed, as well as the potential land and water requirements to define 2 technology-based scenarios, representing the highest and lowest potential environmental impact. 2 different legislative frameworks (current and restrictive) were also assessed, to give 4 combined scenarios altogether. Land consumption and allocation patterns of well pads varied substantially according to the modelled scenario. Potential landscape fragmentation and conflicts with other land users depended mainly on development rate, well pad density, existing land-use patterns, and geology. Highly complex landscapes presented numerous barriers to drilling activities, restricting the potential development patterns. The land used for shale gas development could represent a significant percentage of overall land take within the shale play. The adoption of appropriate legislation, especially the protection of natural areas and water resources, is therefore essential to minimise the related environmental impact. -- Highlights: •A range of scenarios for shale gas development in Poland were modelled. •The impact in terms of land take and competition for land was assessed. •Of land used for industrial purposes, 7–12% was attributed to shale gas extraction. •If unregulated, 24% of well pads were developed within protected areas. •The legislative framework can have a major influence on overall environmental impact

  11. Natural resources and their prospects in the closed basins of rift valley marginal grabens in northern Ethiopia

    Science.gov (United States)

    Meaza, Hailemariam; Frankl, Amaury; Poesen, Jean; Zenebe, Amanuel; Deckers, Jozef; Vaneetvelde, Veerle; Lanckriet, Sil; Nyssen, Jan

    2016-04-01

    With increasing population, producing more food and fibers has led to an expansion of the area under cultivation. For this, much attention is given to low-lying flat areas in search of suitable agricultural lands. The objectives of this paper are therefore: (1) to review the opportunities and challenges of natural resources in the marginal grabens for rural development; (2) to highlight the knowledge gaps and priorities in research and development in the marginal grabens, and (3) to supplement the literature review through repeat transect walks, focus group discussions and interviews across the western rift valley of northern Ethiopia. The paper shows that marginal grabens along the rift valleys are rich both in blue and green water resources due to their topographical and geological characteristics. Spate irrigation has been a growing water management practice to respond to soil moisture deficit. Besides, marginal grabens are fertile plains as a result of alluvial deposition that could be suitable for agricultural development. However, rainfall variability and groundwater withdrawal lead to graben basin closure and salinization. Notably, riverbed incisions and sediment deposition affects drainage systems and water supply in the marginal grabens. As a result, socioeconomic and natural capital of the marginal graben farmers are continuously threatened. Thus, the benefits of natural resources for rural development in the marginal grabens along the rift valley can be optimized if the current bottlenecks are converted into opportunities. A better understanding of the complex marginal graben system via a robust land evaluation framework will improve livelihoods of the communities that live in the (closed) marginal grabens. Keywords: population pressure, marginal grabens, endorheic lakes, salinization, Ethiopia

  12. Formation of hydrothermal deposits at Kings Triple Junction, northern Lau back-arc basin, SW Pacific: The geochemical perspectives

    Science.gov (United States)

    Paropkari, Anil L.; Ray, Durbar; Balaram, V.; Surya Prakash, L.; Mirza, Imran H.; Satyanarayana, M.; Gnaneshwar Rao, T.; Kaisary, Sujata

    2010-04-01

    An inactive hydrothermal field was discovered near Kings Triple Junction (KTJ) in northern Lau back-arc basin during 19th cruise of R/V Akademik Mstislav Keldysh in 1990. The field consisted of a large elongated basal platform 'the pedestal' with several 'small' chimneys on its periphery and one 'main mound' superposed over it. The surrounding region is carpeted with lava pillows having ferromanganese 'precipitate' as infillings. The adjoining second field consisted of small chimney like growths termed as 'Christmas Tree' Field. The basal pedestal, the peripheral chimneys and small 'Christmas Tree' like growths (samples collected by MIR submersibles), though parts of the same hydrothermal field, differ significantly in their mineralogy and elemental composition indicating different history of formation. The pedestal slab consisting of chalcopyrite and pyrite as major minerals and rich in Cu is likely to have formed at higher temperatures than sphalerite dominated peripheral chimney. Extremely low concentration of high field strength elements (e.g. Zr, Hf, Nb and Ta) and enrichment of light REE in these sulfides indicate prominent influence of aqueous arc-magma, rich in subduction components. The oxide growths in the 'Christmas Tree' Field have two distinct layers, Fe rich orange-red basal part which seems to have formed at very low temperature as precipitates from diffused hydrothermal flows from the seafloor whereas Mn rich black surface coating is formed from hydrothermal fluids emanated from the seafloor during another episode of hydrothermal activity. Perhaps this is for the first time such unique hydrothermal oxide growths are being reported in association with hydrothermal system. Here, we discuss the possible processes responsible for the formation of these different hydrothermal deposits based on their mineralogy and geochemistry.

  13. Innovative Methodology for Detection of Fracture-Controlled Sweet Spots in the Northern Appalachian Basin

    Energy Technology Data Exchange (ETDEWEB)

    Robert Jacobi; John Fountain; Stuart Loewenstein; Edward DeRidder; Bruce Hart

    2007-03-31

    For two consecutive years, 2004 and 2005, the largest natural gas well (in terms of gas flow/day) drilled onshore USA targeted the Ordovician Trenton/Black River (T/BR) play in the Appalachian Basin of New York State (NYS). Yet, little data were available concerning the characteristics of the play, or how to recognize and track T/BR prospects across the region. Traditional exploration techniques for entry into a hot play were of limited use here, since existing deep well logs and public domain seismic were almost non-existent. To help mitigate this problem, this research project was conceived with two objectives: (1) to demonstrate that integrative traditional and innovative techniques could be used as a cost-effective reconnaissance exploration methodology in this, and other, areas where existing data in targeted fracture-play horizons are almost non-existent, and (2) determine critical characteristics of the T/BR fields. The research region between Seneca and Cayuga lakes (in the Finger Lakes of NYS) is on strike and east of the discovery fields, and the southern boundary of the field area is about 8 km north of more recently discovered T/BR fields. Phase I, completed in 2004, consisted of integrating detailed outcrop fracture analyses with detailed soil gas analyses, lineaments, stratigraphy, seismic reflection data, well log data, and aeromagnetics. In the Seneca Lake region, Landsat lineaments (EarthSat, 1997) were coincident with fracture intensification domains (FIDs) and minor faults observed in outcrop and inferred from stratigraphy. Soil gas anomalies corresponded to ENE-trending lineaments and FIDs. N- and ENE-trending lineaments were parallel to aeromagnetic anomalies, whereas E-trending lineaments crossed aeromagnetic trends. 2-D seismic reflection data confirmed that the E-trending lineaments and FIDs occur where shallow level Alleghanian salt-cored thrust-faulted anticlines occur. In contrast, the ENE-trending FIDs and lineaments occur where Iapetan

  14. Innovative Methodology for Detection of Fracture-Controlled Sweet Spots in the Northern Appalachian Basin

    Energy Technology Data Exchange (ETDEWEB)

    Robert Jacobi; John Fountain; Stuart Loewenstein; Edward DeRidder; Bruce Hart

    2007-03-31

    For two consecutive years, 2004 and 2005, the largest natural gas well (in terms of gas flow/day) drilled onshore USA targeted the Ordovician Trenton/Black River (T/BR) play in the Appalachian Basin of New York State (NYS). Yet, little data were available concerning the characteristics of the play, or how to recognize and track T/BR prospects across the region. Traditional exploration techniques for entry into a hot play were of limited use here, since existing deep well logs and public domain seismic were almost non-existent. To help mitigate this problem, this research project was conceived with two objectives: (1) to demonstrate that integrative traditional and innovative techniques could be used as a cost-effective reconnaissance exploration methodology in this, and other, areas where existing data in targeted fracture-play horizons are almost non-existent, and (2) determine critical characteristics of the T/BR fields. The research region between Seneca and Cayuga lakes (in the Finger Lakes of NYS) is on strike and east of the discovery fields, and the southern boundary of the field area is about 8 km north of more recently discovered T/BR fields. Phase I, completed in 2004, consisted of integrating detailed outcrop fracture analyses with detailed soil gas analyses, lineaments, stratigraphy, seismic reflection data, well log data, and aeromagnetics. In the Seneca Lake region, Landsat lineaments (EarthSat, 1997) were coincident with fracture intensification domains (FIDs) and minor faults observed in outcrop and inferred from stratigraphy. Soil gas anomalies corresponded to ENE-trending lineaments and FIDs. N- and ENE-trending lineaments were parallel to aeromagnetic anomalies, whereas E-trending lineaments crossed aeromagnetic trends. 2-D seismic reflection data confirmed that the E-trending lineaments and FIDs occur where shallow level Alleghanian salt-cored thrust-faulted anticlines occur. In contrast, the ENE-trending FIDs and lineaments occur where Iapetan

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

    Directory of Open Access Journals (Sweden)

    HÉCTOR HUGO VARELA

    2006-06-01

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

  16. Zircon Hf isotopic constraints on the mantle source of felsic magmatic rocks in the Phan Si Pan uplift and Tu Le basin, northern Vietnam

    Science.gov (United States)

    Usuki, T.; Lan, C.; Tran, T.; Pham, T.; Wang, K.

    2013-12-01

    Permian plume-related rocks, such as picrites, flood basalts and silicic volcanic rocks occur in northern Vietnam. This area was displaced 600 km southeastward along the Ailao Shan-Red River fault during mid-Tertiary in response to the India-Eurasia collision. The original location of the area was situated at the central Emeishan Large Igneous Province (ELIP) in SW China before Tertiary. The picrites and flood basalts in northern Vietnam have been investigated by many authors and are comparable with the ELIP. While, felsic magmatisms in northern Vietnam has been poorly studied. Zircon U-Pb age and Hf isotopic data are useful to compare the felsic magmatism in northern Vietnam with that in the ELIP, because the magmatisms of the ELIP had a characteristic time period (260-250 Ma) and the Hf isotopes show a remarkable mantle signature. Therefore, this study carried out in-situ U-Pb ages and Hf isotopic compositions for 300 zircon grains in eighteen granitoids and rhyolites in Phan Si Pan uplift and Tu Le basin in northern Vietnam. Zircons from the granitoids and rhyolites occasionally show development of {101} pyramid and {100} prism crystal facies, suggesting typical zircons crystallized from high temperature alkaline granite. 206Pb/238U ages of granitoid and rhyolite yield consistently in a narrow range of 260 to 250 Ma, which coincides with those from peralkaline to metaluminous granites in the ELIP. ɛHf(t) values of zircons in rhyolites and granites of this study dominate in the range of +5 to +10, which is consistent with those from the ELIP. U-Pb ages and Hf isotopic compositions of zircons indicate that felsic magmatic rocks in the Phan Si Pan uplift and Tu La basin have been derived from the same mantle source with the ELIP.

  17. Eocene to late Oligocene history of crustal shortening within the Hoh Xil Basin and implications for the uplift history of the northern Tibetan Plateau

    Science.gov (United States)

    Staisch, Lydia M.; Niemi, Nathan A.; Clark, Marin K.; Chang, Hong

    2016-04-01

    The timing and magnitude of deformation across the northern Tibetan Plateau are poorly constrained but feature prominently in geodynamic models of the plateau's evolution. The Fenghuoshan fold and thrust belt, located in the Hoh Xil Basin, provides a valuable record of the Cenozoic deformation history of the northern Tibetan Plateau. Here we integrate fault gouge geochronology, low-temperature thermochronology, geologic mapping, and a balanced cross section to resolve the deformation history of Hoh Xil Basin. Chronologic data suggest that deformation initiated in the mid-Eocene continued until at least 34 Ma and ceased by 27 Ma. The balanced cross section resolves 34 ± 12 km upper crustal shortening (24 ± 9%). We explore whether the observed Cenozoic shortening can account for the modern elevation and lithospheric thickness in the northern Tibetan Plateau. For a range of reasonable preshortening conditions, we conclude that the observed shortening alone cannot achieve modern crustal and mantle lithospheric thicknesses or modern elevation without either the removal of lithospheric mantle, the influx of lower crustal material, or some combination of these processes. Our results, along with previous studies, suggest that crustal shortening propagated into the northern Tibetan Plateau shortly after the onset of the Indo-Asian collision. The small magnitude of shortening and the late Oligocene cessation of deformation in the northern Tibetan Plateau raise questions of how and where the remaining Indo-Asian convergence was accommodated between Eocene to mid-Miocene time, prior to the approximately late Miocene establishment of the deformation patterns observed in the present day.

  18. Middle-Upper Ordovician (Darriwilian-Early Katian) Positive Carbon Isotope Excursions in the Northern Tarim Basin, Northwest China:Implications for Stratigraphic Correlation and Paleoclimate

    Institute of Scientific and Technical Information of China (English)

    Cunge Liu; Guorong Li; Dawei Wang; Yongli Liu; Mingxia Luo; Xiaoming Shao

    2016-01-01

    ABSTRACT:Three positive carbon isotope excursions are reported from Middle–Upper Ordovician in Tahe oil-gas field, northern Tarim Basin. Based on conodont biostratigraphy, the Middle Darriwilian Isotope Carbon Excursion (MDICE) and the Guttenberg Carbon Isotope Excursion (GICE) are identified from Darriwilian to Early Katian by the aid of whole-rock carbon isotope data from two well cores. Positive excursion within conodont Pygodus anserinus zone is developed in Early Sandbian, and the fluctuation range is no less than MDICE. Because the range of this excursion in the generalized global carbon isotope curve is short, previous studies paid little attention to it, and named Early Sandbian Isotope Carbon Excursion (ESICE) in this paper. Furthermore, these positive excursions are not directly related to sea level fluctuations and the MDICE and GICE identified in northern Tarim can be globally correlated to that in southern China, North America, South America, and Europe. The Saergan Fm. source rocks of Middle-Upper Ordovician in Kalpin Dawangou outcrop are in accord with the geologic time of MDICE and ESICE, and GICE have strong ties to the source rock of Lianglitag Fm. in basin. Abundant organic carbon burial is an important factor in genesis of positive isotope carbon excursions. Positive oxygen isotope excursion, conodont fauna turnover, decreased conodont total diversity, and the change of sedimentary facies indicated that dramatic changes of paleoceanographic environment of Early-Middle Ordovician in Tarim Basin started from the end of Darriwillian, and an obvious icehouse climate of Late Ordovician occurred in ESICE.

  19. Fission track analysis and evolution of mesozoic-paleozoic hydrocarbon resource-rocks headed in Northern Jiangsu-South Yellow sea basin

    International Nuclear Information System (INIS)

    Fission track data of different geologic epoches from Binhai salient, Yancheng sag, Haian sag, Baiju sag, Gaoyou sag, Hongze sag and Jinhu sag of northern Jiangsu basin and seismic data from Laoshan uplift in South Yellow Sea basin and evolution of Paleozoic hydrocarbon resource-rocks headed in the Northern Jiangsu-South Yellow Sea basin were studied. Results indicate that Binhai salient uplifted in 38-15 Ma, forming 'structure uplifting model', Paleozoic hydrocarbon resource-rocks have the appearance of 'different layers but identical mature, different layers but identical temperature' with Laoshan uplift. All sags have the characters of 'long time heating model', and sedimentations in Cenozoic were exploited by 2 km. Mesozoic-Paleozoic hydrocarbon resource- rocks of Laoshan uplift get ahead of 10 km. Structure evolution was compared with Binhai salient. According to the modeling results of secondary hydrocarbon generation, Mesozoic-Paleozoic hydrocarbon resource-rocks of Laoshan uplift have the good reservoir potentiality and probably become an important new window for sea oil and gas exploration. (authors)

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

    International Nuclear Information System (INIS)

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

  1. Adding the human dimension to drought: an example from Chile

    Science.gov (United States)

    Rangecroft, Sally; Van Loon, Anne; Maureira, Héctor; Rojas, Pablo; Alejandro Gutiérrez Valdés, Sergio; Verbist, Koen

    2016-04-01

    Drought and water scarcity are important hazards and can lead to severe socio-economic impacts in many regions of the world. Given the interlinked interactions and feedbacks of hydrological droughts and their impacts and management, we need tools to evaluate these complexities and effects on the availability of water resources. Here we use a real-world case study of the Huasco basin (Northern Chile) in which we quantify the influence of human activities on hydrological drought signals. In this arid region, Andean snowmelt provides water essential for users, with agriculture acting as the main water consumer (85% of total). An increasing water demand from different water sectors (agriculture, mining, and domestic water usage) has increased pressure on available water and its management. Consequently, the Santa Juana dam was built by 1995 to increase irrigation security for downstream users, and recent management and restrictions have been established with the objective to limit impacts of hydrological droughts across the basin. The feedbacks between water availability and water management are explored for this water stressed region in Chile. Hydro-meteorological (e.g. precipitation, temperature, streamflow, reservoir levels) variables have been analysed to assess trends and drought patterns. Data over the past three decades has indicated a decrease in surface water supply, with the basin entering a situation of water scarcity during the recent multiyear drought (2007 - to-date), partly caused by meteorological drought and partly by abstraction. During this period, water supply failed to meet the demands of water users, resulting in the implementation of water restrictions. As well as the necessary continuous hydro-meteorological data, here we used information on human water users and scenario modeling, allowing for the analysis and quantification of feedbacks. This work highlights the importance of local knowledge, especially in understanding water laws, rights

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

    DEFF Research Database (Denmark)

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

    2008-01-01

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

  3. A regional view of urban sedimentary basins in Northern California based on oil industry compressional-wave velocity and density logs

    Science.gov (United States)

    Brocher, T.M.

    2005-01-01

    Compressional-wave (sonic) and density logs from 119 oil test wells provide knowledge of the physical properties and impedance contrasts within urban sedimentary basins in northern California, which is needed to better understand basin amplification. These wire-line logs provide estimates of sonic velocities and densities for primarily Upper Cretaceous to Pliocene clastic rocks between 0.1 - and 5.6-km depth to an average depth of 1.8 km. Regional differences in the sonic velocities and densities in these basins largely 1reflect variations in the lithology, depth of burial, porosity, and grain size of the strata, but not necessarily formation age. For example, Miocene basin filling strata west of the Calaveras Fault exhibit higher sonic velocities and densities than older but finer-grained and/or higher-porosity rocks of the Upper Cretaceous Great Valley Sequence. As another example, hard Eocene sandstones west of the San Andreas Fault have much higher impedances than Eocene strata, mainly higher-porosity sandstones and shales, located to the east of this fault, and approach those expected for Franciscan Complex basement rocks. Basement penetrations define large impedence contrasts at the sediment/basement contact along the margins of several basins, where Quaternary, Pliocene, and even Miocene deposits directly overlie Franciscan or Salinian basement rocks at depths as much as 1.7 km. In contrast, in the deepest, geographic centers of the basins, such logs exhibit only a modest impedance contrast at the sediment/basement contact at depths exceeding 2 km. Prominent (up to 1 km/sec) and thick (up to several hundred meters) velocity and density reversals in the logs refute the common assumption that velocities and densities increase monotonically with depth.

  4. Geometry of the El Fresnal basin, northern Chihuahua, Mexico, as inferred from three-dimensional gravity modeling (parte A)

    OpenAIRE

    W. L. Bandy; J. Ortega Ramírez; J. M. Maillol; A. Valiente Banuet; Rodríguez, J. A.

    2002-01-01

    A multidisciplinary study of the El Fresnal basin, Chihuahua, Mexico is being conducted to investigate the relationships between the structure, vegetation and geomorphology and the Quaternary paleoenvironment. As part of this study, 221 new gravity measurements were collected within the basin and combined with 506 preexisting measurements from the surrounding area to determine the basin geometry and the depth of the sediment infill. A basement-depth model calculated from these data indicates ...

  5. Pockmark development in the Petrel Sub-basin, Timor Sea, Northern Australia: Seabed habitat mapping in support of CO2 storage assessments

    Science.gov (United States)

    Nicholas, W. A.; Nichol, S. L.; Howard, F. J. F.; Picard, K.; Dulfer, H.; Radke, L. C.; Carroll, A. G.; Tran, M.; Siwabessy, P. J. W.

    2014-07-01

    The extent to which fluids may leak from sedimentary basins to the seabed is a critical issue for assessing the potential of a basin for carbon capture and storage. The Petrel Sub-basin, located beneath central and eastern Joseph Bonaparte Gulf in tropical northern Australia, was identified as potentially suitable for the geological storage of CO2 because of its geological characteristics and proximity to offshore gas and petroleum resources. In May 2012, a multidisciplinary marine survey (SOL5463) was undertaken to collect data in two targeted areas of the Petrel Sub-basin to facilitate an assessment of its CO2 storage potential. This paper focuses on Area 1 of that survey, a 471 km2 area of sediment-starved shelf (water depths of 78 to 102 m), characterised by low-gradient plains, low-lying ridges, palaeo-channels and shallow pockmarks. Three pockmark types are recognised: small shallow unit pockmarks 10-20 m in diameter (generally mangrove deposits and shells to have begun after 15.5 cal ka BP when a rapid marine transgression of Bonaparte Shelf associated with meltwater pulse 1A drowned coastal mangrove environments. Pockmark development is likely an ongoing process driven by fluid seepage at the seabed, and sourced from CO2 produced in the shallow sub-surface (<2 m) sediment. No evidence for direct connection to deeper features was observed.

  6. Application of the authigenic 10Be/9Be dating method to Late Miocene-Pliocene sequences in the northern Danube Basin (Pannonian Basin System): Confirmation of heterochronous evolution of sedimentary environments

    Science.gov (United States)

    Šujan, Michal; Braucher, Régis; Kováč, Michal; Bourlès, Didier L.; Rybár, Samuel; Guillou, Valéry; Hudáčková, Natália

    2016-02-01

    Authigenic 10Be/9Be dating method was applied to lacustrine, deltaic and alluvial sequences of the northern Danube Basin (Pannonian Basin System), to bridge the insufficiency of geochronological data for the Late Miocene to Pliocene period. The measurements of 51 samples (both lacustrine and floodplain), ranging from 11.6 to 0.95 Ma are consistent with the existing magnetostratigraphic and biostratigraphic data standing mainly on the evolution degree of endemic mollusk fauna, mammals and dinocysts. This agreement confirms our assumption that the incoming beryllium fluxes remained constant over the studied time period and thus that the two initial 10Be/9Be ratios determined in actual Holocene/Late Pleistocene sediments (lacustrine and floodplain) are valid for these environments. The obtained ages indicate gradual progradation of the deltaic depositional systems across the Danube Basin with a clear time-transgressional character, replacing basin floor and shelfal environments. Deltaic sedimentation occurred firstly in the north at foothills of the Western Carpathians from 11.0 Ma, and changed to the alluvial environment after 10.5 Ma. At the same time (~ 10.5 Ma), the paleo-Danube deltaic system draining the Eastern Alps entered the study area from the Vienna Basin situated on the West. Later, the deltaic systems were merged in the central part of the basin and reached its southeastern margin at ~ 9.4 Ma. Regression of the Lake Pannon from the southernmost part of the study area is evidenced after 8.7 Ma. Alluvial deposition of meandering rivers lasting until 6.0-5.0 Ma followed and was interrupted by the early Pliocene basin inversion. Sedimentation of braided streams took place during the late Pliocene and Pleistocene, reflecting uplift of mountains surrounding the basin margins. This study documents the powerful potential of the authigenic 10Be/9Be dating method and its reliability in a basin with complicated tectonic and sedimentary history. It demonstrates that

  7. Miocene Bahean stratigraphy in the Longzhong Basin,northern central China and its implications in environmental change

    Institute of Scientific and Technical Information of China (English)

    LI; Jijun; ZHANG; Jun; SONG; Chunhui; ZHAO; Zhijun; ZHANG; Yong; WANG; Xiuxi; ZHANG; Jianming; CUI; Qiaoyu

    2006-01-01

    Fossil mammal-riched Neogene strata are widely distributed in the southeast corner of the huge Longzhong Basin at Tianshui,Gansu Province,northern central China.Hipparion weihoense,a typical member of late Middle Miocene Bahean stage,was recently excavated at Yaodian along a well-exposed outcrop.Owing to the importance of the Bahean stage in the mammalian evolution and its potential for environmental change,we suggested a name of Yaodian Formation for the stratigraphy,which is correlated to the Bahe Formation at Lantian,Shaanxi.High resolution paleomagnetic dating of the section shows that the Yaodian Formation covers the period between 11.67 Ma and 7.43 Ma,with the site bearing Hipparion weihoense being estimated at about 10.54-10.30 Ma,providing first magnetostratigraphic chronology for the Bahean Stage.The Yaodian Formation consists of fluvial channel deposits (11.67-10.40 Ma) at the bottom,floodplain deposits in the middle (10.40-9.23 Ma) and shallow lake sediments at the top (9.23-7.43 Ma).This upward fining sequence suggests that the relief in nearby mountain ranges such as West Qinling to the south and Huajia Ling to the north was greatly reduced after long-term denudation,fluvial transport capacity was low,and finally the drainage system was disintegrated,replaced with broad-shallow lakes in which only fine sediments like mud and marlite were deposited,indicating an old stage of development of a planation surface.A remarkable shift in ecology and climatic environment was found at 7.4-7.7 Ma when paleoclimate changed from early warm humid to late dry as indicated by sedimentary facies changed from early shallow lake sequence to late eolian red clays and a former coniferous-deciduous mixed forest was replaced by grassland,leading to great growth of Hipparion Fauna of Baodean stage in the region.Therefore,it is estimated that the present high relief of Qinling and drainage pattern did not come into being until Late Pliocene in response to intensive

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

    Science.gov (United States)

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

    2006-02-01

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

  9. Report on the Predation Index, Predator Control Fisheries, and Program Evaluation for the Columbia River Basin Experimental Northern Pikeminnow Management Program, 2008 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Porter, Russell [Pacific States Marine Fisheries Commission].

    2009-09-10

    This report presents results for year seventeen in the basin-wide Experimental Northern Pikeminnow Management Program to harvest northern pikeminnow1 (Ptychocheilus oregonensis) in the Columbia and Snake Rivers. This program was started in an effort to reduce predation by northern pikeminnow on juvenile salmonids during their emigration from natal streams to the ocean. Earlier work in the Columbia River Basin suggested predation by northern pikeminnow on juvenile salmonids might account for most of the 10-20% mortality juvenile salmonids experience in each of eight Columbia River and Snake River reservoirs. Modeling simulations based on work in John Day Reservoir from 1982 through 1988 indicated that, if predator-size northern pikeminnow were exploited at a 10-20% rate, the resulting restructuring of their population could reduce their predation on juvenile salmonids by 50%. To test this hypothesis, we implemented a sport-reward angling fishery and a commercial longline fishery in the John Day Pool in 1990. We also conducted an angling fishery in areas inaccessible to the public at four dams on the mainstem Columbia River and at Ice Harbor Dam on the Snake River. Based on the success of these limited efforts, we implemented three test fisheries on a system-wide scale in 1991 - a tribal longline fishery above Bonneville Dam, a sport-reward fishery, and a dam-angling fishery. Low catch of target fish and high cost of implementation resulted in discontinuation of the tribal longline fishery. However, the sport-reward and dam-angling fisheries were continued in 1992 and 1993. In 1992, we investigated the feasibility of implementing a commercial longline fishery in the Columbia River below Bonneville Dam and found that implementation of this fishery was also infeasible. Estimates of combined annual exploitation rates resulting from the sport-reward and dam-angling fisheries remained at the low end of our target range of 10-20%. This suggested the need for additional

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

    Directory of Open Access Journals (Sweden)

    ALVARO G SANHUEZA

    2008-12-01

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

  11. Molecular preservation in halite- and perchlorate-rich hypersaline subsurface deposits in the Salar Grande basin (Atacama Desert, Chile): Implications for the search for molecular biomarkers on Mars

    Science.gov (United States)

    FernáNdez-Remolar, D. C.; Chong-DíAz, G.; RuíZ-Bermejo, M.; Harir, M.; Schmitt-Kopplin, P.; Tziotis, D.; Gómez-OrtíZ, D.; GarcíA-Villadangos, M.; MartíN-Redondo, M. P.; Gómez, F.; RodríGuez-Manfredi, J. A.; Moreno-Paz, M.; de Diego-Castilla, G.; EcheverríA, A.; Urtuvia, V. N.; Blanco, Y.; Rivas, L.; Izawa, M. R. M.; Banerjee, N. R.; Demergasso, C.; Parro, V.

    2013-06-01

    Similarities between the Atacama Desert (Chile) and Mars include extreme aridity, highly oxidizing chemistry, and intense ultraviolet radiation that promoted the photochemical production of perchlorates and nitrates. Concentration of these ions under hyperarid conditions led to the formation of nitrate- and perchlorate-bearing deposits in ephemeral lakes, followed by later deposition of chlorides and sulfates. At some locations, such as the Salar Grande, hypersaline deposits have remained unaltered for millions of years. We conducted a drilling campaign in deposits of the Salar to characterize the preservation state of biological molecules. A 5 m deep discontinuous core was recovered and subjected to multitechnique analysis including the antibody microarray-based biosensor LDChip300 and the SOLID (Signs Of Life Detector) instrument, complemented by geophysical, mineralogical, geochemical, and molecular analysis. We identified two units based on the mineralogy: the upper one, from the surface to ~320 cm depth characterized by a predominance of halite and anhydrite, and the lower one, from 320 to 520 cm, with a drop in halite and anhydrite and an enrichment in nitrate and perchlorate. Organic compounds including biomolecules were detected in association with the different depositional and mineralogical units, demonstrating the high capacity for molecular preservation. Hypersaline environments preserve biomolecules over geologically significant timescales; therefore, salt-bearing materials should be high-priority targets for the search for evidence of life on Mars.

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

    Directory of Open Access Journals (Sweden)

    Jorge Rivera

    2005-05-01

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

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

    Science.gov (United States)

    Arriagada, César; Roperch, Pierrick; Mpodozis, Constantino

    2000-11-01

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

  14. The onset of flood basalt volcanism, Northern Paraná Basin, Brazil: A precise U-Pb baddeleyite/zircon age for a Chapecó-type dacite

    Science.gov (United States)

    Janasi, Valdecir de Assis; de Freitas, Vivian Azor; Heaman, Larry H.

    2011-02-01

    We report the first U-Pb baddeleyite/zircon date for a felsic volcanic rock from the Paraná Large Igneous Province in south Brazil. The new date of 134.3 ± 0.8 Ma for a hypocrystalline Chapecó-type dacite from Ourinhos (northern Paraná basin) is an important regional time marker for the onset of flood basalt volcanism in the northern and western portion of the province. The dated dacite was erupted onto basement rocks and is overlain by a high-Ti basalt sequence, interpreted to be correlative with Pitanga basalts elsewhere. This new U-Pb date for the Ourinhos dacite is consistent with the local stratigraphy being slightly older than the few reliable step-heating 40Ar/39Ar dates currently available for overlying high-Ti basalts (133.6-131.5 Ma). This indicates an ~ 3 Ma time span for the building of the voluminous high-Ti lava sequence of the Paraná basin. On the other hand, it overlaps the 40Ar/39Ar dates (134.8-134.1 Ma) available for the stratigraphically older low-Ti basalt (Gramado + Esmeralda types) and dacite-rhyolite (Palmas type) sequences from South Brazil, which is consistent with the short-lived character of this volcanism and its rapid succession by the high-Ti sequence.

  15. Occurrence of Highly Mature Organic Matter in Marine Black Shale Petroleum Source Rocks of Basal Cambrian from Northern Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)

    YU Bingsong (于炳松); Hailiang DONG; CHEN Jianqiang (陈建强); CHEN Xiaolin (陈晓林); LIANG Shiyou (梁世友)

    2004-01-01

    More and more evidence indicates that organic matter (OM) in immature organic-rich sediments and sedimentary rocks is chemically adsorbed onto the outer surfaces of minerals and into interlayer (inner) surfaces of smectitic clay minerals in the form of amorphous molecular-scale carbon. But there have been few reports about the occurrence of highly mature OM in marine black shales (petroleum source rocks). The occurrence of highly mature OM in the black shales of basal Cambrian from northern Tarim Basin is studied in this paper. Based on the comprehensive analyses of total organic carbon contents (TOC), maximum thermolysis temperatures (T max ) of OM, mineral surface areas (MSA), and scanning electronic microscopic (SEM) and transmission electronic microscopic (TEM) observations of the black shales, it is concluded that the highly mature OM in the marine black shales of the basal Cambrian from northern Tarim Basin occurs in particulates ranging in size from 1 to 5 μm in diameter. Through the contrast of the occurrence of the highly mature OM in the black shales with that of the immature ones in modern marine continental margin sediments, some scientific problems are proposed, which are worth to study further in detail.

  16. Study on the relationships between the structural evolution and sandstone-type uranium mineralization in mesozoic era and cenozoic era in the northern of Chaidam basin

    International Nuclear Information System (INIS)

    By detailed expounding the characteristics of the Mesozoic and Cenozoic structural evolution in northern of Chaidam basin, the author inquires into its relationships with the sandstone-type uranium mineralization, analyzes the prospect of forming uranium deposit, and thinks that the Mesozoic and Cenozoic strata are mainly controlled by the tectonic role of the later Yanshan movement and the later Cenozoic era. The north-west palaeo-structural slope belt is formed in the later Cretacous Epoch that is favorable for developing palaeo-interlayer oxidized zone. After the slightly extensional role of the oldest Tertiary and the early Plioeene, the middle and lower Jurassic were buried, and the block-imbricated slope belts are formed in the tectonic movement of the later Cenozoic, which are favorable for developing recent interlayer oxidized zone. According to drilling, it has the conditions for forming palaeo-recent interlayer oxidized zone sandstone-type uranium deposit at the northern of Chaidam basin. Finally, the author lays his finger on the prospecting of uranium. (authors)

  17. Chemical and isotopic tracers of the contribution of microbial gas in Devonian organic-rich shales and reservoir sandstones, northern Appalachian Basin

    International Nuclear Information System (INIS)

    In this study, the geochemistry and origin of natural gas and formation waters in Devonian age organic-rich shales and reservoir sandstones across the northern Appalachian Basin margin (western New York, eastern Ohio, northwestern Pennsylvania, and eastern Kentucky) were investigated. Additional samples were collected from Mississippian Berea Sandstone, Silurian Medina Sandstone and Ordovician Trenton/Black River Group oil and gas wells for comparison. Dissolved gases in shallow groundwaters in Devonian organic-rich shales along Lake Erie contain detectable CH4 (0.01-50.55 mol%) with low δ13C-CH4 values (-74.68 to -57.86 per mille) and no higher chain hydrocarbons, characteristics typical of microbial gas. Nevertheless, these groundwaters have only moderate alkalinity (1.14-8.72 meq/kg) and relatively low δ13C values of dissolved inorganic C (DIC) (-24.8 to -0.6 per mille), suggesting that microbial methanogenesis is limited. The majority of natural gases in Devonian organic-rich shales and sandstones at depth (>168 m) in the northern Appalachian Basin have a low CH4 to ethane and propane ratios (3-35 mol%; C1/C2 + C3) and high δ13C and δD values of CH4 (-53.35 to -40.24 per mille, and -315.0 to -174.6 per mille, respectively), which increase in depth, reservoir age and thermal maturity; the molecular and isotopic signature of these gases show that CH4 was generated via thermogenic processes. Despite this, the geochemistry of co-produced brines shows evidence for microbial activity. High δ13C values of DIC (>+10 per mille), slightly elevated alkalinity (up to 12.01 meq/kg) and low SO4 values (13C-DIC values (4 concentrations (up to 12.31 mmole/L) in many brine samples point to SO4 reduction, which likely limits microbial CH4 generation in the Appalachian Basin. Together the formation water and gas results suggest that the vast majority of CH4 in the Devonian organic-rich shales and sandstones across the northern Appalachian Basin margin is thermogenic in

  18. The Formation of a Retroarc Fold-Thrust Belt by the Closure and Inversion of a Back-Arc Basin; Patagonian-Fuegian Fold-Thrust Belt, Chile

    Science.gov (United States)

    Betka, P.; Klepeis, K. A.; Mosher, S.

    2012-12-01

    The Late Cretaceous closure and inversion of the Late Jurassic Rocas Verdes back-arc basin (RVB) defines the onset of the Andean orogeny and the development of the Patagonian retroarc fold-thrust belt (FTB) between 50°-54.5° S. Back-arc extension in the RVB led to the generation of new oceanic crust that was coeval with the deposition of syn-rift silicic volcanoclastic rocks on the continental margin. A > 500 m thick succession of mudstone and distal turbidite deposits accumulated in the RVB (post-rift). New maps and line-balanced cross-sections from three transects across the FTB show a transition through time from thin-to thick-skinned structural styles that is controlled by the inherited stratigraphic architecture and structure of the RVB. The closure of the RVB and development of the FTB occurred in two stages. During the initial stage, mafic schist, gabbro, basalt, and hemipelagic mudstone of the RVB floor were imbricated and thrust onto the continental margin resulting in the formation of the Magallanes foreland basin and underthrusting of the continental crust to depths of ~ 35 km. Displacement from the obduction of the RVB was transferred along two decollement levels into the FTB by ~85 Ma. Each decollement level formed at a rheological boundary within the syn- and post-rift stratigraphy. The lower decollement formed in quartz-chlorite schist (basement) > 1 km beneath the top-basement contact with relatively strong syn-rift volcanoclastic deposits. The lower decollement is defined by a ~1 km thick ductile shear zone. C-S fabrics, C-C' shear bands and prominent SW plunging quartz stretching lineations that occur within the shear zone indicate a top-NE transport direction. Isoclinal recumbent F2 folds and inclined tight F3 folds refold the S1/L1 surface. The decollement cuts up-section through the syn-rift volcanoclastic deposits to join a structurally higher decollement that formed within weak, post-rift mudstone and turbidite deposits on the continental

  19. The Pre-historical Eruption of Volcanoes Near a Capital-city: Inferred From Tephra Deposits in the Taipei Basin, northern Taiwan

    Science.gov (United States)

    Chen, C.; Lin, C.

    2006-12-01

    The volcanic pyroclastic flows, lahars and/or ashes derived from volcanic eruptions are a serious threat of human lives and regional economies, especially in the densely populated area. In case, more than two million populations in the capital-city Taipei, northern Taiwan just live in the vicinity of the Tatun Volcanic Group (TVG), how to make effective and reliable volcanic hazard mitigation is absolutely mandatory. Volcano is a pretty complex system. Hazard mitigation can be achieved only by applying numerous techniques. Understanding the recent eruptive history will be the most important information for prediction the future activity of eruption. After 1995, the Center Geological Survey of Ministry of Economic Affair handled to drill more than 20 wells in the Taipei basin to investigate the subsurface geology of basin. These continuous core samples offered the best materials to investigate if any volcanic ashes had deposited in the basin. The young juvenile volcanic ashes V pumice tuff were firstly identified in the two cores of the Kuantu well (KT- 1) and the Shihlin well (SL-1 in the late Pleistocene Sunshan formation. According to the radiocarbon (C-14) ages of core samples (Lin et al, 1998, Shieh, 2001), the time of this tephra deposit was extrapolated around 18.6 kyrs C-14 B.P.. Respecting, this tephra would like to be temperately named as the 18 kyrs Taipei Tuff (18 KTT). These air-fall ash deposits found in the core directly demonstrated that there had been re-active in the TVG in the recent time. More notable thing is that there are three historical records of submarine eruptions in northern offshore Taiwan, then, a program of the volcanic hazard reduction should be seriously considered around the capital city-Taipei.

  20. Large-scale thrusting along the northern margin of the Tibetan Plateau and the southwest Tarim basin: 230 km long active Hotian thrust sheet

    Science.gov (United States)

    Suppe, J.; Wang, X.; He, D.; Liang, H.

    2015-12-01

    We present the geometry, kinematics and mechanics of large-scale active thrusting in the western Kunlunshan and southwest Tarim basin, which accounts for ~130-165km total shortening of Tarim crust at the northern margin of Tibet. The great frontal structure is the ~230km long bedding-parallel Hotian thrust sheet, which is perhaps the longest active intact thrust sheet in the world, composed of flat-lying strata of the Tarim basin sliding northward on a regional gypsum detachment at the base of the Cenozoic sequence. The toe of the Hotian thrust ramps to the surface two thirds of the way across the Tarim basin, forming the Selibuya-Mazartag hills in the Taklamakan sand desert. At the southern edge of the Tarim basin in the Kunlunshan foothills, a set of high-amplitude anticlines are growing by complex break-forward ramping and wedging in the Hotian thrust sheet as it steps up to the Cenozoic gypsum detachment from a regional Cambrian evaporate detachment that extends under Tibet. More interior structures such as the Tiklik thrust bring older strata and Proterozoic basement to the surface, together with their Cenozoic Tarim cover in the Buya basin. The Cambrian detachment also extends northward under the Tarim basin with minor hanging-wall deformation that locally warps the overlying Hotian thrust sheet, producing a complete syntectonic record in seismically imaged growth strata of its northward motion over these warps. Seismic profiles in the southwest Tarim foothill belt also reveal widespread growth strata that record much of the structural history beginning in the early Pliocene Atushi Formation. Ages of seismic reflectors are calibrated to a surface magnetostratigraphic sequence (Zheng et al., 2000). The beginning of thrusting and folding in the southwest Tarim basin north of the Tiklik thrust is dated at 3.6Ma with shortening >25km and a progressive northward propagation toward the Selibuya-Mazartag hills. The overall shortening rate is ~10 mm/yr. The gypsum

  1. Actual Evapotranspiration in the Al-Khazir Gomal Basin (Northern Iraq Using the Surface Energy Balance Algorithm for Land (SEBAL and Water Balance

    Directory of Open Access Journals (Sweden)

    Hussein Jassas

    2015-04-01

    Full Text Available Increasing dependence on groundwater requires a detailed determination of the different outputs and inputs of a basin for better water management. Determination of spatial and temporal actual evapotranspiration (ETa, in this regard, is of vital importance as there is significant water loss from drainage basins. This research paper uses the Surface Energy Balance Algorithm for Land (SEBAL, as well as the water balance, to estimate the spatial and temporal ETa in the Al-Khazir Gomal Basin, Northern Iraq. To compensate for the shortage in rainfall, and to irrigate summer crops, farmers in this basin have been depending, to a large extent, on groundwater extracted from the underlying unconfined aquifer, which is considered the major source for both domestic and agricultural uses in this basin. Rainfed farming of wheat and barley is one of the most important activities in the basin in the winter season, while in the summer season, agricultural activity is limited to small rice fields and narrow strips of vegetable cultivation along the Al-Khazir River. The Landsat Thematic Mapper images (TM5 acquired on 21 November 2006, 9 March 2007, 5 May 2007, 21 July 2007, and 23 September 2007 were used, along with a digital elevation model (DEM and ground-based meteorological data, measured within the area of interest. Estimation of seasonal ETa from periods between satellite overpasses was computed using the evaporative fraction (Ʌ. The water balance approach was utilized, using meteorological data and river hydrograph analysis, to estimate the ETa as the only missing input in the predefined water balance equation. The results of the two applied methods were comparable. SEBAL results were compared with the land use land cover (LULC map. The river showed the highest ETa, as evaporation from the free-water surface. Rice fields, irrigated in the summer season, have a high ETa in the images, as these fields are immersed in water during June, July and August

  2. Advanced interpretation of land subsidence by validating multi-interferometric SAR data: the case study of the Anthemountas basin (Northern Greece

    Directory of Open Access Journals (Sweden)

    F. Raspini

    2013-10-01

    Full Text Available The potential of repeat-pass space borne SAR (Synthetic Aperture Radar interferometry has been exploited to investigate spatial patterns of land subsidence in the Anthemountas basin, in the northern part of Greece. The PSI (Persistent Scatterer Interferometry approach, based on the processing of long series of SAR acquisitions, has been applied to forty-two images acquired in 1995–2001 by ERS1/2 satellites. Interferometric results have been analysed at a basin scale as support for land motion mapping and at a local scale for the characterisation of ground motion events affecting the village of Perea in the Thermaikos municipality and the "Macedonia" international airport. PSI results revealed a moderate subsidence phenomenon along the wider coastal zone of Anthemountas basin corresponding to intense groundwater extraction. Highest values, exceeding −20 mm yr−1, were measured in the airport area where the thickest sequence of compressible Quaternary sediments occurs. Intense subsidence has been detected also in the Perea village (maximum deformation of −10 to −15 mm yr−1, where a series of fractures, causing damages to both buildings and infrastructure, occurred in 2005–2006.

  3. Geodetic vs. Geologic Measures of Fault Slip Rates in the Northern Walker Lane, Basin and Range Province, Western United States

    Science.gov (United States)

    Hammond, W. C.; Kreemer, C.; Blewitt, G.

    2008-05-01

    Quantifying faults slip rates and styles is an important objective in the study of crustal deformation. Fault slip rates are used to quantify seismic hazard associated with active faults, and are an important input into the U.S.G.S. seismic hazard maps. However, when multiple types of data (e.g. geologic, seismic and geodetic) are used to measure slip rates, results from the different techniques can be corroborative, complementary, or in direct conflict. Geologic methods provide some of the only constraints on slip rates of individual faults over hundreds to tens of thousands of years, time scales that are significant with respect to observed deformation patterns, and likely representative of modern hazard. On the other hand geodetic measurements provide strong constraints on the medium to long spatial wavelength (>50 km) budgets of deformation, and on geographic changes in deformation style, and have the potential to provide geographically complete measurements of surface deformation. However, geodetic measurements can be influenced by earthquake cycle effects, e.g. owing to interseismic fault locking and postseismic relaxation, which limit their ability to resolve individual slip rates, especially in complex systems with many closely spaced faults. The northern Walker Lane (NWL), in the western Basin and Range Province (BRP) of the United States, is an example of a complex system of dextral, normal and sinestral faults that work together to accommodate approximately 10 mm/yr of relative motion between the Sierra Nevada/Great Valley block and the central part of the BRP. To exploit the strengths of each dataset, we have built a detailed model of NWL crustal blocks and are using geodetic and geologic data to resolve patterns of crustal deformation. We use a block modeling technique that incorporates the strengths of both targeted geologic investigations of slip rates on individual faults and longer wavelength constraints offered by GPS geodesy. To constrain these

  4. Platform-induced clay-mineral fractionation along a northern Tethyan basin-platform transect: implications for the interpretation of Early Cretaceous climate change (Late Hauterivian-Early Aptian)

    OpenAIRE

    Godet, Alexis; Bodin, Stéphane; Adatte, Thierry; Föllmi, Karl B.

    2009-01-01

    High-resolution clay-mineral analyses were performed on upper Hauterivian to lower Aptian sediments along a platform-to-basin transect through the northern Tethyan margin from the Neuchâtel area (Switzerland), to the Vocontian Trough (France) in order to investigate links between climate change, carbonate platform evolution, and fractionation patterns in clay minerals during their transport. During the Hauterivian, the northern Tethyan carbonate platform developed in a heterozoan mode, and t...

  5. The stratigraphic record of the Messinian salinity crisis in the northern margin of the Bajo Segura Basin (SE Spain)

    OpenAIRE

    Soria Mingorance, Jesús Miguel; Caracuel Martín, Jesús Esteban; Yébenes Simón, Alfonso; Fernández Martínez, Juan (1945-); Viseras Alarcón, César

    2005-01-01

    The Bajo Segura Basin is a marginal basin of the Western Mediterranean located on the eastern end of the Betic Cordillera (southeastern Spain). Its Messinian and Pliocene stratigraphic record is divided into four allostratigraphic units, with bounding unconformities represented by erosional surfaces corresponding to palaeogeographic changes. The Messinian Unit I (MI) is composed of three depositional systems (fluvial, coastal lagoon, and shelf) which lateral facies changes, deposited...

  6. Development of an integrated water resources management plan for the Lake Manyara sub-basin, Northern Tanzania

    Science.gov (United States)

    Ngana, J. O.; Mwalyosi, R. B. B.; Madulu, N. F.; Yanda, P. Z.

    Water resources management in Lake Manyara sub-basin is an issue of very high significance as the sub-basin hosts a number of national and global assets of great socio-cultural, ecological and economic values. The sub-basin comprise of a Biosphere Reserve with boosting tourism from Lake Manyara National Park with a variety of wildlife population, large livestock population and highly fertile land for agricultural production. The prevailing system of uncoordinated water resources management in the sub-basin cannot sustain the ever increasing water needs of the various expanding sectors, therefore a strategy must be sought to integrate the various sectoral needs against the available water resources in order to attain both economic and ecological sustainability. Through participatory approach with the stakeholders, the study has established key issues, demonstrated considerable experience in water resources management in the sub-basin including existence of water boards, water committees in some districts as well as land resources management practices However, a number of constraints were noted which inhibit sustainable water resources management including ignorance of water policies, conflicting sectoral policies, lack of coordination between sectors, high in migration rates into the basin, heavy in migration of livestock, conflicts between sectors, poor land use resulting in soil erosion and sedimentation, lack of comprehensive data base on water resources and water needs for : domestic, tourism, livestock, irrigation, wild life and environmental flows. As a way forward it was recommended that a basin wide legally mandated body (involving all levels) be established to oversee water use in the sub-basin. Other strategies include capacity building of stakeholders on water natural resources management policies, water rights and enforcement of laws. This progress report paper highlights the wealth of knowledge that stakeholders possess on water resources management and

  7. Eocene to Miocene back-arc basin basalts and associated island arc tholeiites from northern Sulawesi (Indonesia): Implications for the geodynamic evolution of the Celebes basin

    International Nuclear Information System (INIS)

    Eocene BABB basalts intruded by tholeiitic and calk-alkalic island arc magmatic rocks are reported from the north arm of Sulawesi (Indonesia). Age and geochemical similarities between these basalts and those drilled in the Celebes Sea indicate this North Sulawesi volcanic arc was built on the same oceanic crust. The 25 deg late Neogene clockwise rotation of the north arm of Sulawesi following its collision with fragments of Australia (Sula, Buton) is not sufficient to explain the asymmetrical magnetic anomalies in the Celebes basin. The North Sulawesi island arc could be interpreted as having progressively retreated northward on its own Celebes sea back arc basin, during an episode of Palaeogene-early Neogene tectonic erosion along the trench. (authors)

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

    Directory of Open Access Journals (Sweden)

    SOLANGE J GONZÁLEZ

    2008-12-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

  10. Detection of detached forced-regressive nearshore wedges: a case study from the central-southern Siena Basin (Northern Apennines, Italy)

    Science.gov (United States)

    Martini, Ivan; Arragoni, Simone; Aldinucci, Mauro; Foresi, Luca Maria; Bambini, Anna Maria; Sandrelli, Fabio

    2013-07-01

    The detection of detached nearshore wedges formed in response to relative sea-level drops is considered one of the hottest topics in sequence stratigraphic analysis due to their importance as reservoir analogues. In fact, they usually constitute sandy and porous bodies generally encased in impermeable clay, thus presenting a good potential as traps for fluids. This paper focuses on the sequence stratigraphic analysis of the Pliocene deposits cropping out in the central-southern sector of the Siena Basin (Tuscany, Italy), a post-collisional basin of the Northern Apennines. The exposed sedimentary succession was investigated through a detailed sedimentological and stratigraphic approach, integrated by biostratigraphic analyses, aimed at a better characterization of the infilling history of this sector of the basin. Specifically, this study revealed the occurrence of repeated facies shifts that allowed the identification of two depositional sequences. In detail, a thick sand-rich body far from the basin margins, and previously considered as a turbiditic lobe, has been reinterpreted as formed in a nearshore setting during a fall in relative sea level. This body is totally encased in offshore clay, and due to the lack of physical connection with the related HST deposits, it has to be considered as a detached forced-regressive wedge. The present work led to the recognition of some sedimentological and stratigraphic features typical of falling stage systems tract deposits (e.g. presence of intrabasinal recycled materials, sedimentological evidence of a pre-existing fluvial network subsequently eroded) that can provide useful clues for the identification of detached forced-regressive nearshore wedges in core studies and poorly exposed settings.

  11. A new genus of dactylogyrid from the gills of Galaxias maculatus (Osmeriformes: Galaxiidae) in Maullín Basin, Patagonia, Chile.

    Science.gov (United States)

    Viozzi, Gustavo P; Marin, Sandra L; Carvajal, Juan; Brugni, Norma; Mancilla, Melinka

    2007-06-01

    During a parasitological survey of Galaxias maculatus (Jenyns, 1842) in the Maullín Basin (Chilean Patagonia), specimens of a new species of Monogenea were collected from the gills. This species is described as the only member of a proposed new genus, Inserotrema n. gen. (Dactylogyridae, Ancyrocephalinae), characterized by similar hooks with 2 subunits, overlapping gonads, coiled cirrus with counterclockwise rings, articulated accessory piece formed by 2 parts, a needlelike sclerite threading the distal part of the MCO, and a sclerotized midventral vagina. This new genus is proposed for dactylogyrids from gills of galaxiids (Galaxiidae). Inserotrema puyei n. sp. infects gills of G. maculatus from Llanquihue Lake, Maullín River, and Maullín Estuary. This is the first species of Ancyrocephalinae described from gills of a galaxiid. PMID:17626345

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

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    Eleuterio Yáñez R.

    1999-01-01

    Full Text Available Se usó el modelo lineal general para estandarizar el índice de abundancia relativa, captur