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Sample records for cordillera se spain

  1. Active faulting in the internal zones of the central Betic Cordilleras (SE, Spain)

    NASA Astrophysics Data System (ADS)

    Galindo-Zaldívar, J.; Gil, A. J.; Borque, M. J.; González-Lodeiro, F.; Jabaloy, A.; Marín-Lechado, C.; Ruano, P.; Sanz de Galdeano, C.

    2003-09-01

    The internal zones of the Betic Cordilleras show a present-day relief that is mainly controlled by kilometre-size, symmetrical or north-vergent folds which developed mostly since Middle Miocene times. The Sierra Nevada, Sierra Alhamilla, Sierra de Los Filabres, Sierra Tejeda and Sierra de Gádor, among others, are roughly E-W trending high mountain ranges, corresponding to antiforms where metamorphic rocks crop out. The surrounding depressions are located in synforms, where Neogene rocks are preserved from erosion. Field evidence shows that the growth of the folds is coeval with fault development, and that at least three of them, i.e. the Padul Fault, the Zafarraya Fault, and the Balanegra Fault, may be considered to be active seismogenetic structures. The Zafarraya Fault, in particular, is thought to be responsible for the 1884 Andalucı´a Earthquake. The fault is located at the northern limb of the Sierra Tejeda antiform, and could be interpreted as a collapse structure developed along the external arch of the uplifted fold. The Padul and Balanegra faults are located at the southeastern border of the Granada Basin and south of the Sierra de Gádor, respectively. They belong to a set of NW-SE oriented faults that are mainly normal in character and indicate NE-SW extension. The set up, since 1999, of a GPS network within and around the Granada Basin and the planed installation of a new network in the Sierra Tejeda, will give us new insights on the present-day deformation behaviour of both folds and faults in the area.

  2. Plio-Pleistocene drainage development in an inverted sedimentary basin: Vera basin, Betic Cordillera, SE Spain

    NASA Astrophysics Data System (ADS)

    Stokes, Martin

    2008-08-01

    The Vera basin is one of a series of interconnected Neogene-Quaternary sedimentary basins located within the Internal Zone of the Betic Cordillera (southeast Spain). Since the Pliocene the Vera basin has been subjected to low uplift rates (11-21 m Ma - 1 ) and inverted via compressive tectonics that are related to the ongoing oblique collision between the African and Iberian plates. Within this paper the sedimentary and geomorphic response to basin inversion is explored. Sedimentary processes and environments are established for key stratigraphic units of the Pliocene/Plio-Pleistocene basin fill and Pleistocene dissectional landscape. These data are subsequently utilised to reconstruct an evolving basin palaeogeography. Fault and uplift data are employed to discuss the role of tectonically driven basin inversion for controlling the resultant palaeogeographic changes and associated patterns of drainage development. During the Early-Mid Pliocene the Vera basin was characterised by shallow marine shelf conditions (Cuevas Formation). A major palaeogeographic reorganisation occurred during the Mid-Late Pliocene. Strike-slip movement along the eastern basin margin, coupled with uplift and basin emergence created a protected, partially enclosed marine embayment that was conducive for Gilbert-type fan-delta sedimentation from fluvial inputs along the northern and eastern basin margins (Espíritu Santo Formation). The Vera basin then became fully continental and internally drained through the development of a consequent drainage network that formed following the withdrawal of marine conditions during the Late Pliocene to Early Pleistocene. Alluvial fans developed along the northern and western basin margins, grading to a bajada and terminating in a playa lake in central basin areas (Salmerón Formation). During the Early-Mid Pleistocene a switch from basin infilling to dissection took place, recorded by alluvial fan incision, a switch to braided river sedimentation and

  3. Paleoseismic and geomorphologic evidence of recent tectonic activity of the Pozohondo Fault (Betic Cordillera, SE Spain)

    USGS Publications Warehouse

    Rodríguez-Pascua, M.A.; Pérez-López, R.; Garduño-Monroy, V.H.; Giner-Robles, J.L.; Silva, P.G.; Perucha-Atienza, M.A.; Hernández-Madrigal, V.M.; Bischoff, J.

    2012-01-01

    Instrumental and historical seismicity in the Albacete province (External Prebetic Zone) has been scarcely recorded. However, major strike-slip faults showing NW-SE trending provide geomorphologic and paleoseismic evidence of recent tectonic activity (Late Pleistocene to Present). Moreover, these faults are consistently well oriented under the present stress tensor and therefore, they can trigger earthquakes of magnitude greater than M6, according to the lengths of surface ruptures and active segments recognized in fieldwork. Present landscape nearby the village of Hellin (SE of Albacete) is determined by the recent activity of the Pozohondo Fault (FPH), a NW-SE right-lateral fault with 90 km in length. In this study, we have calculated the Late Quaternary tectonic sliprate of the FPH from geomorphological, sedimentological, archaeoseimological, and paleoseismological approaches. All of these data suggest that the FPH runs with a minimum slip-rate of 0.1 mm/yr during the last 100 kyrs (Upper Pleistocene-Holocene). In addition, we have recognized the last two major paleoearthquakes associated to this fault. Magnitudes of these paleoearthquakes were gretarer than M6 and their recurrence intervals ranged from 6600 to 8600 yrs for the seismic cycle of FPH. The last earthquake was dated between the 1st and 6th centuries, though two earthquakes could be interpreted in this wide time interval, one at the FPH and other from a far field source. Results obtained here, suggest an increasing of the tectonic activity of the Pozohondo Fault during the last 10,000 yrs.

  4. Striated and pitted pebbles as paleostress markers: an example from the central transect of the Betic Cordillera (SE Spain)

    NASA Astrophysics Data System (ADS)

    Ruano, Patricia; Galindo-Zaldívar, Jesús

    2004-02-01

    Striated and pitted pebbles provide scarce structures that preserve information on the stresses that their host rocks have undergone. This information can be obtained by the measurement of a large number of microfaults with striae and solution marks within a small rock volume. For non-rotational deformation, the statistical procedures for microfault analysis provide a valid tool for determining the overprinting of successive stress ellipsoids, including their axial ratios and the orientations of the main axes. The trends of compressions obtained from striae can be compared with the determinations from the pole of pebble solution pits. However, in complex tectonics settings, the solution pits of several deformation phases are mixed and only striae analysis allows overprinted paleostresses to be accurately distinguished. The analysis of several pebbles from the same outcrop, including five from moderately complex settings, allows determination of the homogeneity of the paleostresses at outcrop scale, the detection of redeposited pebbles, and supports the results of microtectonic analysis for large areas. Solution mark distributions on pebbles depend on the burial and tectonic stresses. Conglomerates from shallow levels, such as those from Quaternary fluvial terraces, only record horizontal compressional solution marks because the minimum vertical stress needed to develop these structures are not reached by burial. In the central Betic Cordillera, striated and pitted pebbles are composed of carbonate surrounded by a matrix containing siliciclastic elements. The study of several outcrops located across a transect of the Cordillera shows a change in the recent stress field. While conglomerates near the Internal-External zone boundary show extensional stresses that may be related to the uplift of the Cordillera since Tortonian times, the outcrops located in the External Zone and up to the mountain front indicate the existence of horizontal NW-SE and NE-SW compressions

  5. A cross section of the eastern Betic Cordillera (SE Spain) according field data and a seismic reflection profile

    NASA Astrophysics Data System (ADS)

    Jabaloy-Sánchez, A.; Fernández-Fernández, E. M.; González-Lodeiro, F.

    2007-04-01

    The BT3 multichannel seismic profile was acquired by the C.G.G. (Compagnie General de Géophysique) in 1977 for hydrocarbon exploration in the eastern Betic Cordillera. REXIMseis Ltd scanned and vectorized a paper copy and then performed post-stack processing, including coherence filtering and deconvolution. The receiver functions of a broad-band seismic station located near the village of Vélez Rubio, at the SE end of the profile, were analysed by Julia et al. [Julia, J., Mancilla, F., Morales, J., 2005. Seismic signature of intracrustal magmatic intrusions in the Eastern Betics (Internal Zone), SE Iberia, Geophysical Research Letters 32, L16304, doi:10.1029/2005GL023274.] to determine the structure of the underlying crust. We have used these Vp data to convert the profile to depth. The profile has a mean SE-NW trend, with a SE-Section 44 km in length followed by a NW-Section 20 km in length. The record includes the first 4 s (twtt), which corresponds to 11 km. Two main areas can be seen in the profile. At the SE-end, a band of high-amplitude discontinuous reflectors dips towards the north. The band is 100 to 200 ms thick, increasing even more northwards. This band reaches the surface at the top of the Maláguide Complex (the upper complex of the Internal Zones). Above these reflectors, an area with chaotic seismic facies and no reflectors corresponds to the outcrops of the olistostromes and turbidites of the Solana Formation, and it is in turn overlain by discontinuous reflectors of the Subbetic rocks. At the NW-end of the profile, a set of high-amplitude continuous reflectors with SE dips point to the location of the Prebetic. Below this section, oblique reflectors of intermediate amplitude indicate the Variscan basement. Over the Prebetic, we have marked the basal thrusts of the Intermediate Units and the Subbetic. Using this seismic data, as well as field observations, we propose a geological cross-section of the upper crust of the eastern Betic Cordillera

  6. Structure of the Maláguide Complex near Vélez Rubio (Eastern Betic Cordillera, SE Spain)

    NASA Astrophysics Data System (ADS)

    FernáNdez-FernáNdez, E. M.; Jabaloy-SáNchez, A.; Nieto, F.; GonzáLez-Lodeiro, F.

    2007-08-01

    The Maláguide Complex of the Betic Cordillera represents a tectonic element which mostly underwent brittle deformation during the Alpine orogeny, and that covers the high-pressure/low-temperature (HP/LT) complexes of the internal Betic Cordillera. The evolution of this complex can help to determine both when the lower HP/LT complexes began to exhume and the behavior of the upper plate during this process. Moreover, this complex is a key element to understanding the relationships between the late orogenic extension in the internal Betic Cordillera and the coeval compression in the External Zones of the same mountain chain. This paper focuses in the geometry and kinematics of the Alpine structures of this Maláguide Complex in the eastern Betic Cordillera, near the village of Vélez Rubio. We propose that these Alpine structures can be grouped into three main stages. First stage (Paleogene) began with a synmetamorphic slaty cleavage produced in anchizone conditions. This foliation is associated with northward vergent structures and was probably connected with the superposition of the Maláguide Complex over the Alpujárride during the middle Eocene. This first stage ended with the thinning of the Maláguide Complex (Oligocene) by an extensional detachment with a top-to-the-NNW sense of movement. Second stage records the convergence of the External and Internal Zones during the Aquitanian-Burdigalian. This convergence was a right-lateral transpression that produced back thrusts and extensional structures that exhumed the HP/LT rocks of the Alpujárride Complex. Third stage corresponds to the evolution from the late Burdigalian to the present-day, when the Internal and External zones were welded together.

  7. Hydrothermal activity and its paleoecological implications in the latest Miocene to Middle Pleistocene lacustrine environments of the Baza Basin (Betic Cordillera, SE Spain)

    NASA Astrophysics Data System (ADS)

    García-Aguilar, José Manuel; Guerra-Merchán, Antonio; Serrano, Francisco; Palmqvist, Paul; Flores-Moya, Antonio; Martínez-Navarro, Bienvenido

    2014-07-01

    The continental sedimentary record of the Baza Basin (Guadix-Baza Depression, Betic Cordillera, SE Spain) shows six sedimentary units of lacustrine origin deposited from the latest Miocene to the Middle Pleistocene. Depending on the interval considered, the lacustrine deposits are mainly composed of marls, carbonates or gypsiferous evaporites, showing lithological, mineralogical and geochemical features (i.e., magnesium, strontium and sulfur contents, celestine deposits and travertine growths) that are evidence of intense, tectonically-induced hydrothermal activity. According to the high concentrations of strontium and sulfur as well as the abundance of travertines and magnesium clays, the supply of hot waters was greater during the Zanclean, the Gelasian and the Calabrian, as a result of tectonic activity. Hydrothermal activity has continued until the present time and is responsible of the hot springs that are nowadays active in the Guadix-Baza Depression. The paleoenvironmental consequences of these sublacustrine hot springs were that during some intervals the lakes maintained a relatively permanent water table, not subject to periodic desiccations in the dry season, and warmer temperatures throughout the year. This resulted in a high level of organic productivity, especially for the Calabrian, which allowed the development of a rich and well diversified mammalian community, similar to those of modern African savannas with tree patches. In this mild environment, the permanent water sheet favored the presence of drought intolerant megaherbivores such as the giant extinct hippo Hippopotamus antiquus. The high standing crop biomass of ungulates resulted in the availability of abundant carcasses for scavengers such as hyenas and hominins, which explains the very high densities of skeletal remains preserved in the sediments distributed along the lake surroundings.

  8. Subduction- and exhumation-related structures preserved in metaserpentinites and associated metasediments from the Nevado-Filábride Complex (Betic Cordillera, SE Spain)

    NASA Astrophysics Data System (ADS)

    Jabaloy-Sánchez, Antonio; Gómez-Pugnaire, María Teresa; Padrón-Navarta, José Alberto; López Sánchez-Vizcaíno, Vicente; Garrido, Carlos J.

    2015-03-01

    The Cerro del Almirez massif (Nevado-Filábride Complex, Betic Cordillera, SE Spain) is composed of antigorite (Atg-) serpentinite and chlorite (Chl-) harzburgite separated by a thin reaction front formed in a palaeo-subduction setting. These ultramafic rocks preserve unique prograde structures related to the pre- and peak high-pressure event (1.6-1.9 GPa and 680-710 °C). The oldest subduction-related structures are preserved in Atg-serpentinites: a penetrative S1 foliation and associated L1 stretching lineation that formed in a non-coaxial regime with a top-to-the-W sense of shear. This planar-linear fabric is crosscut by olivine ± Ti-clinohumite veins, formed during the prograde breakdown of brucite and pre-metamorphic clinopyroxene, which form a system of veins decimetres long. They record embrittlement processes due to the release of 6 vol.% of H2O associated with brucite dehydration. The growth of prograde olivine and/or tremolite porphyroblasts is syn- to post-kinematic in relation to the S1 foliation. Further reactions at higher temperature related to the complete breakdown of the Atg (i.e. Atg-out) are post-kinematic to S1. Prograde Chl-harzburgite is crosscut by sets of conjugate zones associated with grain-size reduction of olivine grains. These grain-size reduction zones are interpreted as brittle structures generated by hydrofracturing due to overpressure fluids in a compressional setting at low-differential stresses. Structures related to the exhumation process are mainly preserved in the metasedimentary host rock, where an S2/L2 planar-linear fabric developed within a shear zone dominated by a non-coaxial regime with a top-to-the-W sense of movement in a transpressional regime. Peak metamorphic conditions deduced for the schists are similar in pressure (1.3-1.9 GPa) but lower in temperature (560-590 °C) compared to the ultramafic rocks in contact with them, suggesting a major shear zone at the base of the ultramafic massif during D2 deformation in

  9. Flow in the shallow mantle in the westernmost Mediterranean: insights from xenoliths in Plio-Pleistocene alkali basalts from the eastern Betic Cordillera (SE Spain)

    NASA Astrophysics Data System (ADS)

    Konc, Zoltán; Hidas, Károly; Garrido, Carlos J.; Tommasi, Andréa; Vauchez, Alain; Padrón Navarta, José Alberto; Marchesi, Claudio; Acosta-Vigil, Antonio; Szabó, Csaba; Varas-Reus, Maria Isabel

    2016-04-01

    Peridotite mantle xenoliths in Plio-Pleistocene alkali basalts of the eastern Betic Cordillera (Cartagena area, Murcia, SE Spain) provide a snapshot of the structure and composition of the lithospheric mantle at the northern limb of the Alpine Betic-Rif arched belt in the westernmost Mediterranean. The xenoliths are spinel and plagioclase lherzolite with minor harzburgite and wehrlite, displaying porphyroclastic to equigranular textures. Regardless of composition and texture, the Crystal Preferred Orientation (CPO) of olivine shows an axial-[100] pattern characterized by a strong alignment of [100]-axes near or parallel to the peridotite lineation and a girdle distribution of [010]-axes with a maximum normal to the peridotite foliation. This CPO pattern is consistent with ductile deformation accommodated by dislocation creep with dominant activation of the high temperature {0kl}[100] olivine slip system, indicative of deformation by simple shear or combinations of simple shear and pure shear with a transtensional component. Calculated seismic properties are characterized by fast propagation of P-waves and polarization of fast S-waves parallel to olivine [100]-axis, indicating the flow direction. SKS and Pn anisotropy in the eastern Betics can be explained by a lithospheric mantle peridotite with similar fabric to the one displayed by the studied mantle xenoliths. Considering the limited thickness of the mantle lithosphere in the Betics (40-80 km), the measured azimuths and delays of SKS waves in the eastern Betics are consistent with a steeply dipping mantle foliation and a subhorizontal lineation with ENE strike. This geometry of the lithospheric fabrics implies active or frozen mantle flow with a dominantly strike-slip component subparallel to the paleo-Iberian margin. Synkinematic overprinting of mineral assemblages from the garnet-spinel to the plagioclase facies demonstrates 36-40 km uplift continuously accommodated by ductile shear thinning of the

  10. Significance of nodule formation for the interpretation of matrix micrite C and O isotope ratios in Upper Jurassic Ammonitico Rosso limestones (Betic Cordillera, SE Spain)

    NASA Astrophysics Data System (ADS)

    Coimbra, R.; Immenhauser, A.; Olóriz, F.

    2009-04-01

    Three Ammonitico Rosso (AR) sections from the Betic Cordillera in SE Spain were analysed to obtain stable isotope records and access paleoenvironmental information. The study area corresponded to a Late Jurassic distal epioceanic setting and is characterized by the occurrence of more or less calcareous AR horizons ranging from greyish to redish colour. The carbonate materials under scope where retrieved from the Cardador, Salcedo and Cañada del Hornillo sections and consist on matrix micrite, carbonate cements and skeletals and were analysed for their carbon and oxygen isotope signature. At least one bulk sample per ammonite biozone was retrieved under a strict biochronostratigraphic control. The degree of diagenetic imprint was acessed by cathodoluminiscence analysis and carbonate ultrastructure was analysed by scanning electron microscope. Micrite matrix showed dull luminiscence, revealing a low degree of diagenetic overprint, as oposite to carbonate cements and skekeltal materials, that presented bright orange luminiscence. The identification of coccoliths and filaments under SEM attested for the good degree of preservation of the carbonate ultrastructure. The carbon isotope chemostratigraphy resembles the known trends for Jurassic northern Tethyan margins and absolute values (from 1.1 to 3.3 permil) are within the range usually reported for well preserved material. Oxygen isotopes of matrix micrite samples present higher values than those expected for Upper Jurassic materials (ranging from -0.3 to 0.9 permil for the Cardador and Salcedo sections and from -2.1 to 0.4 permil at the Cañada del Hornillo section), whilts commonly well preserved low-Mg calcite skeletal materials, such as belemenite rostra present lower values than matrix micrite, acompanied by a very bright orange luminiscence. In contrast to what is usually reported, matrix micrite presents values closer to what would be the original isotopic composition and skeletal material is more affected by

  11. Neotectonic evolution of the Central Betic Cordilleras (Southern Spain)

    NASA Astrophysics Data System (ADS)

    Reicherter, Klaus R.; Peters, Gwendolyn

    2005-08-01

    Paleostress orientations were calculated from fault-slip data of 36 sites located along a traverse through the Central Betic Cordilleras (southern Spain). Heterogeneous fault sets, which are frequent in the area, have been divided into homogeneous subsets by cross-cutting relationships observed in the field and by a paleostress stratigraphy approach applied on each individual fault population. The state of stress was sorted according to main tectonic events and a new chronology is presented of the Miocene to Recent deformation in the central part of the Betic Cordilleras. The deviatoric stress tensors fall into four distinct groups that are regionally consistent and correlate with three Late Oligocene-Aquitanian to Recent major tectonic events in the Betic Cordilleras. The new chronology of the neotectonic evolution includes, from oldest to youngest, the following main tectonic phases: Late Oligocene-Aquitanian to Early Tortonian: σ1 subhorizontal N-S, partly E-W directed, σ3 subvertical; compressional structures (thrusting of nappes, large-scale folding) and strike-slip faulting in the Alborán Domain and the External Zone of the Betic Cordilleras; Early Tortonian to Pliocene-Pleistocene: σ1 subvertical, σ3 subhorizontal NW-SE, partly N-S directed or E-W-directed (radial extension); large-scale normal faulting in the Central Betic Cordilleras and in the oldest Neogene formations of the Granada Basin related to the gravitational collapse of the Betic Cordilleras and the exhumation of the intensely metamorphosed rock series of the Internal Zones, at the same time formation of the Alborán Basin and intramontane basins such as the Granada Basin; Pleistocene to Recent: (3a) σ1 subvertical, σ3 subhorizontal NE-SW with prominent normal faulting, but coevally; (3b) σ1 subhorizontal NW directed, σ3 NE-SW subhorizontal with strike-slip faulting. Extensional structures and strike-slip faulting are related to the ongoing convergence of the Eurasian and African Plates

  12. The dynamics of serpentinite dehydration reactions in subduction zones: Constrains from the Cerro del Almirez ultramafic massif (Betic Cordillera, SE Spain)

    NASA Astrophysics Data System (ADS)

    Dilissen, Nicole; Garrido, Carlos J.; López Sánchez-Vizcaíno, Vicente; Padrón-Navarta, José Alberto

    2015-04-01

    Arc volcanism, earthquakes and subduction dynamics are controlled by fluids from downgoing slabs and their effect on the melting and rheology of the overlying mantle wedge. High pressure dehydration of serpentinite in the slab and the subduction channel is considered as one of the main sources of fluids in subduction zones. Even though this metamorphic reaction is essential in subduction activities, the behavior of the fluids, the kinetics and thermodynamics during the breakdown reaction are still poorly understood. The Cerro del Almirez (Nevado-Filábride Complex, Betic Cordillera, SE Spain) uniquely preserves the dehydration front from antigorite serpentinite to chlorite-harzburgite and constitutes a unique natural laboratory to investigate high-pressure dehydration of serpentinite. This reaction occurred in a subduction setting releasing up to 13 wt% of water, contributing significantly to the supply of fluids to the overlying mantle wedge. A key to the understanding of the metamorphic conditions prevailing during serpentinite dehydration is to study the two prominent textures -granofels and spinifex-like chlorite harzburgite- occurring in this reaction product. The detailed texture differences in the Chl-harzburgite can provide insights into diverse kinetic and thermodynamic conditions of this dehydration reaction due to variations in effective pressure and drainage conditions. It has been proposed that difference in overpressure (P') and deviation from growth equilibrium, i.e. overstepping, is responsible for these two types of textures [Padrón-Navarta et al., 2011]. The magnitude and duration of P' is highly dependent on dehydration kinetics [Connolly, 1997]. The fast pressure drop, with spinifex-texture as a product, can be linked to draining events expected after hydrofracturing, which are recorded in grain size reduction zones in this massif. According to this hypothesis, mapping of textural variation in Chl-harzburgite might be used as a proxy to

  13. High-resolution clay mineralogy as a proxy for orbital tuning: Example of the Hauterivian-Barremian transition in the Betic Cordillera (SE Spain)

    NASA Astrophysics Data System (ADS)

    Moiroud, Mathieu; Martinez, Mathieu; Deconinck, Jean-François; Monna, Fabrice; Pellenard, Pierre; Riquier, Laurent; Company, Miguel

    2012-12-01

    The response of clay mineral assemblages to potential orbital forcing is tested in Mesozoic hemipelagic marl-limestone rhythmites of the Río Argos section (Betic Cordillera, Southeastern Spain). Along the section, marls are pervasively enriched in kaolinite and illite, whereas limestones are enriched in smectite-rich illite/smectite mixed-layers, suggesting that marl-limestone alternations are produced by cyclic high-frequency fluctuations of continental runoff. Spectral analyses show that clay mineral assemblages evolve accordingly to precession, obliquity and eccentricity cycles. Durations of ammonite zones are assessed at 535 kyr for the Late Hauterivian Pseudothurmannia ohmi Zone and at 645 kyr and for the Early Barremian Taveraidiscus hugii Zone. These durations are in agreement with other cyclostratigraphic estimates but significantly differ from the Geologic Time Scale 2004 and 2008. Clay minerals display enhanced amplitude of the eccentricity cycles during the Faraoni Oceanic Anoxic Event due to enhanced continental weathering conditions prevailing at that time. Sedimentary expression of the 405-kyr eccentricity is disturbed by palaeoclimate changes during the Faraoni OAE, challenging the hypothesis of Cretaceous OAE triggered by eccentricity cycles. Although palaeoceanographic events (e.g. Faraoni OAE) may induce disturbances in the clay mineral record, this study demonstrates the potential of these minerals to be used as a proxy for orbital calibration in Mesozoic times.

  14. Multi-stage evolution of the lithospheric mantle beneath the westernmost Mediterranean: Geochemical constraints from peridotite xenoliths in the eastern Betic Cordillera (SE Spain)

    NASA Astrophysics Data System (ADS)

    Marchesi, Claudio; Konc, Zoltán; Garrido, Carlos J.; Bosch, Delphine; Hidas, Károly; Varas-Reus, María Isabel; Acosta-Vigil, Antonio

    2017-04-01

    Spinel (± plagioclase) peridotite xenoliths from the Tallante and Los Perez volcanic centres in the eastern Betics (SE Spain) range from depleted (clinopyroxene-poor) harzburgites to fertile (clinopyroxene-rich) lherzolites and orthopyroxene-free wehrlites. Significantly, only one harzburgite, which is depleted in heavy rare earth elements (HREE), retains the imprint of ca. 20% ancient melting of an original garnet lherzolite source. In contrast, REE abundances of other harzburgites and lherzolites from the eastern Betics have been increased by melt-rock reaction. The whole-rock and mineral compositions of these mantle rocks are largely controlled by three types of modal metasomatism: 1) common clinopyroxene-orthopyroxene addition and olivine consumption which increased FeOt, SiO2 and Al2O3, and decreased MgO compared to the refractory melting products; 2) subordinate orthopyroxene dissolution and precipitation of clinopyroxene and olivine, which led to higher FeOt and MgO and lower SiO2 than in common (orthopyroxene-rich) lherzolites; and 3) rare orthopyroxene consumption and olivine addition that caused higher FeOt and lower SiO2 compared to the original melting residues. These mineral modal and major element variations have been produced mostly by interactions with relatively FeOt-rich/SiO2-poor melts, likely derived from a peridotite-pyroxenite lithospheric mantle with a highly heterogeneous isotopic composition. Melting of the lithospheric mantle in the western Mediterranean was triggered by upwelling of the asthenosphere induced by back-arc extension in the Late Oligocene-Early Miocene. Trapping of small fractions of exotic melts in whole-rocks - likely the parental magmas of Miocene back-arc dykes that intruded the Betic crust - caused local disequilibrium between the trace element signatures and Pb isotopic compositions of clinopyroxene and whole-rock. Subsequent interaction with SiO2-undersaturated magmas, similar to the parental melts of the Pliocene

  15. Subduction- vs- Intraplate-Type Melt Migration in the Alboran Lithospheric Mantle: Insights From the Tallante Xenoliths (Betic Cordillera, SE Spain)

    NASA Astrophysics Data System (ADS)

    Rampone, E.; Vissers, R. L.; Poggio, M.; Scambelluri, M.; Zanetti, A.

    2008-12-01

    The Alboran Sea region has been affected since the late Oligocene by widespread eruption of tholeiitic to calc-alkaline magmas followed by Late Neogene alkaline basalts. These magmatic episodes are related to Neogene lithospheric extension beneath the Alboran domain, as a consequence of slab roll-back. According to recent models, subduction of oceanic lithosphere caused continental-edge delamination of subcontinental lithosphere, associated with upwelling of plume-type mantle sources. The Alboran lithospheric mantle thus constitutes a unique setting to investigate the effects of subduction- and intraplate-type metasomatism. Here we present a microstructural and geochemical study of mantle xenoliths from the Cabezo Tallante Late Neogene alkaline volcanic center (SE Spain). These xenoliths record multiple episodes of reactive porous melt percolation, and melt entrapment, tracking their progressive extension-related uplift from P > 20 Kb to 7-10 Kb. This is documented by i) crystallization of undeformed olivine replacing pyroxene porphyroclasts, and unstrained opx overgrowing undeformed olivine and pyroxene porphyroclasts, in porphyroclastic spinel peridotites, ii) development of annealed equigranular structure, likely enhanced by heating during melt percolation, iii) crystallization of interstitial (plag±ol±opx) aggregates between mantle minerals in porphyroclastic and equigranular xenoliths. Cpx in equigranular peridotites have smooth trace element spectra characterized by slight LREE depletion; computed equilibrium liquids have a tholeiitic-transitional affinity. Diffuse melt percolation was followed by intrusion of melts with distinct chemical affinity. The first event is documented by the intrusion of cm-sized gabbronoritic veins, showing a fine-grained opx reaction rim against the host peridotite. Similar gabbronoritic lithotypes were previously documented and ascribed to slab-derived melts. A quite remarkable textural feature in these veins is the occurrence

  16. Liquefaction and fluidization structures in Messinian storm deposits (Bajo Segura Basin, Betic Cordillera, southern Spain)

    NASA Astrophysics Data System (ADS)

    Alfaro, P.; Delgado, J.; Estévez, A.; Molina, J. M.; Moretti, M.; Soria, J. M.

    2002-05-01

    Synsedimentary deformation structures are recognized in Upper Miocene deposits of the eastern Betic Cordillera (SE Spain). A singular stratigraphic section in these deposits shows several levels with soft-sediment deformation structures (load casts, ball-and-pillows and pipes) induced by liquidization (liquefaction and/or fluidization) of sandy sediments. The morphologic analysis of these structures reveals a liquidized sediment thickness ranging from 0.1 to 1.5 m. Although they have been previously interpreted as a result of seismic shocks, their origin was most likely related to the action of storm waves as the structures are always associated with tempestites. Facies analysis, geometrical features of the deformed beds and appraisal of geotechnical properties for shelf and coastal sediments allow the soft-sediment deformation structures to be interpreted as a result of the cyclic effect of storm waves on unconsolidated sediments, and excludes other processes such as overloading, tsunamis or the impact of breaking waves.

  17. Evolution of near-surface ramp-flat-ramp normal faults and implication during intramontane basin formation in the eastern Betic Cordillera (the Huércal-Overa Basin, SE Spain)

    NASA Astrophysics Data System (ADS)

    Pedrera, Antonio; Galindo-ZaldíVar, Jesús; Lamas, Francisco; Ruiz-ConstáN, Ana

    2012-08-01

    The nucleation, propagation, and associated folding of ramp-flat-ramp normal faults were analyzed from field examples developed in a brittle/ductile multilayer sequence of the Huércal-Overa Basin (SE Spain). Gently dipping sandy silt layers, which display a low cohesive strength (C0 = 7 kPa, μ= 34°), favor the development of extensional detachments. A tectonic origin instead of a possible gravitational origin is supported by the perpendicularity between the paleoslope direction of the fluvial-deltaic environment inferred from imbricated pebbles, and the senses of movement deduced from fault slicken-lines. The link between high-angle normal faults (HANFs) —formed at different levels in the layered sequence— with horizontal fault segments comes to develop ramp-flat-ramp normal faults with associated roll-over in the hanging wall. Observed extensional duplexes are formed by parallel detachments connected through synthetic Riedel faults. These Riedel faults would produce the back-rotation of the individual blocks (horses), i.e., extensional folding of the originally subhorizontal layers. There is no correlation between the analyzed ramp-flat-ramp normal faults, accommodating south-southeastward extension during Serravallian-lower Tortonian, and either the regional Alpujarride/Nevado-Filabride west-directed extensional shear zone or the top-to-the-north detachments within Alpujarride units, which are clearly sealed by Serravallian-lower Tortonian sediments. Therefore, the studied normal faults are restricted to the brittle/ductile multilayer fluvio/deltaic sequence and accommodate moderate late extension instead of belonging to a large crustal extensional system connected with a regional detachment at depth. Therefore, the basin formed in a moderate crustal thickness context where small and medium-scale extensional systems were subordinate structures. These natural examples support the development of low-angle normal faults at very shallow crustal levels in

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

    NASA Astrophysics Data System (ADS)

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

    The CO2-rich thermal groundwater in the Betic Cordilleras in Spain has been studied with regard to the geological and hydrogeological setting, physical and chemical characteristics, and 13C-isotope content. The study area is about 60km northeast of Almería city, in southeastern Spain. The thermomineral waters are plentiful and are related to regional geothermal anomalies. Temperatures of 20 -41°C, high bicarbonate concentrations (183-1824mg/L), and high amounts of PCO2 (<1.1bar) characterize the groundwater. CO2 spatial variations are related to proximity to the Carboneras, Palomares, and Guadalentín fault systems, which may be the surface representation of the zone of crustal thinning and magmatism. δ13C values probably indicate a deep source for the CO2, either the mantle or perhaps carbonate rocks in the metamorphic substratum. The high amount of CO2 in the groundwater causes problems in wells and severely restricts water usage. The hydrothermal features of this area are probably related to neotectonic activity. Résumé Les eaux thermales à teneurs élevées en CO2 des Cordillères Bétiques ont étéétudiées, spécialement en ce qui concerne les aspects géologiques et hydrogéologiques, leurs caractéristiques physiques et chimiques, et leurs teneurs en 13C. La zone d'étude est située à 60km environ au nord-est de la ville d'Almería, au sud-est de l'Espagne. Les eaux thermominérales sont nombreuses et sont en relation avec les anomalies géothermales régionales. L'eau souterraine a une température comprise entre 20-41°C, une concentration élevée en bicarbonates (entre 183 et 1824mg/L), et PCO2élevée (<1.1bars). Les variations spaciales de CO2 sont en rapport avec la proximité des systèmes de failles de Carboneras, Palomares et Guadalentin, et peuvent être la manifestation en surface d'une zone d'amincissement cortical. Les données de δ13C indiquent un apport probable d'origine profonde de CO2, éventuellement du manteau et/ou des

  19. Space-time evolution of a growth fold (Betic Cordillera, Spain). Evidences from 3D geometrical modelling

    NASA Astrophysics Data System (ADS)

    Martin-Rojas, Ivan; Alfaro, Pedro; Estévez, Antonio

    2014-05-01

    We present a study that encompasses several software tools (iGIS©, ArcGIS©, Autocad©, etc.) and data (geological mapping, high resolution digital topographic data, high resolution aerial photographs, etc.) to create a detailed 3D geometric model of an active fault propagation growth fold. This 3D model clearly shows structural features of the analysed fold, as well as growth relationships and sedimentary patterns. The results obtained permit us to discuss the kinematics and structural evolution of the fold and the fault in time and space. The study fault propagation fold is the Crevillente syncline. This fold represents the northern limit of the Bajo Segura Basin, an intermontane basin in the Eastern Betic Cordillera (SE Spain) developed from upper Miocene on. 3D features of the Crevillente syncline, including growth pattern, indicate that limb rotation and, consequently, fault activity was higher during Messinian than during Tortonian; consequently, fault activity was also higher. From Pliocene on our data point that limb rotation and fault activity steadies or probably decreases. This in time evolution of the Crevillente syncline is not the same all along the structure; actually the 3D geometric model indicates that observed lateral heterogeneity is related to along strike variation of fault displacement.

  20. Preliminary palaeomagnetic results from the Subbetic Zone (Betic Cordillera, southern Spain): kinematic and structural implications

    NASA Astrophysics Data System (ADS)

    Osete, M. L.; Freeman, R.; Vegas, R.

    1988-11-01

    We present palaeomagnetic evidence from Jurassic limestones and basic submarine volcanic rocks (sills, pillow lavas, and intrusive material) from the central part of the Subbetic Zone of the Betic Cordillera. Isothermal remanent magnetization acquisition experiments performed on limestones and thermomagnetic curves and measurements of the magnetic susceptibility determined for the volcanic rocks demonstrate strong dependence of rock magnetic properties on lithology. In most cases a stable magnetization could be isolated after thermal and/or alternating field demagnetization. Locally, declinations of the characteristic remanent magnetization from interbedded limestones and volcanics are similar, but inclinations tend to vary. Regionally, declinations for both limestones and volcanics show significant clockwise rotation. These results cannot be explained by the anticlockwise rotation of Iberia during the Cretaceous opening of the Bay of Biscay. Considering the long and complex history of large-scale shear between Africa and Europe accommodated in southern Spain, the anomalous declinations can be explained by a model with rotation of crustal blocks within a zone of wrench tectonics.

  1. Large Holocene morphogenic earthquakes along the Albox fault, Betic Cordillera, Spain

    NASA Astrophysics Data System (ADS)

    Masana, E.; Pallàs, R.; Perea, H.; Ortuño, M.; Martínez-Díaz, J. J.; García-Meléndez, E.; Santanach, P.

    2005-09-01

    The Eastern Betic Shear Zone (EBSZ) in the Betic Cordillera (southern Spain) accommodates part of the Neogene and Quaternary shortening between the Iberian and the African plates. Although the EBSZ is characterised by shallow low to moderate magnitude instrumental seismicity, it seems to be the source of several historical catastrophic events with MSK intensities ranging from VII to X. Despite the fact that it crosses a densely populated area, the seismogenic behaviour of the EBSZ is still poorly understood. The EBSZ is mainly formed by a set of NE-SW-trending left-lateral strike-slip faults, including the Alhama de Murcia and Albox faults. This paper presents a palaeoseismological study of the eastern Albox fault based on surface and trenching observations. This fault ruptures the surface and is probably seismogenic, with short-term slip-rates ranging from 0.01 to 0.4 mm/a. Ground effects of at least two paleoearthquakes were detected: the first one took place not long before 660 years A.D. with an estimated maximum Mw of 6.5 ± 0.1, whereas the second one occurred between 650 A. D. and the XVIII century. The latter produced only a centimetric offset and was not regarded as characteristic. The elapsed time is, therefore, ca. 660 years. The distribution of the long-term cumulative and the short-term ground effects suggest an eastwards migration of the fault tip.

  2. Structural controls on karstic conduits in a collisional orogen (Sierra de las Nieves, Betic Cordillera, S Spain)

    NASA Astrophysics Data System (ADS)

    Pedrera, A.; Luque-Espinar, J. A.; Martos-Rosillo, S.; Pardo-Igúzquiza, E.; Durán-Valsero, J. J.; Martínez-Moreno, F.; Guardiola-Albert, C.

    2015-06-01

    We characterize the fracture pattern, including both meso-scale joints and macro-scale faults, within the central sector of Sierra de las Nieves (Betic Cordillera, S Spain), which contains one of the largest karstification systems in Europe. Structural data were compared with the direction pattern of the karstic conduit network of the largest caves. Carbonate rocks were deformed in a collisional setting and exposed at the surface since the early Miocene. Normal and normal-oblique faults trending NW-SE to WNW-ESE are the most prominent brittle structures, having formed coevally with shorter NE-SW normal to normal-dextral after the main thrusting phase. In addition, two main open joint sets striking NW-SE and NE-SW developed on a broad scale. Orthogonal normal faults and open joints suggest an extensional setting characterized by horizontal minimum (S3) and intermediate (S2) stress axes of similar magnitudes that intermittently shifted their positions during the middle-to-late Miocene. Vertical water flow coming from direct recharge sectors tends to infiltrate across these high-dipping faults, mainly concentrating at fault intersections, thus favoring sub-vertical conduit formation within the vadose zone. Horizontal paleo-phreatic levels are perched linked to the recent uplift undergone by the sector, giving us the opportunity to analyze the incidence of fractures at the phreatic zone. Joint sets determine the hydraulic anisotropy within the former phreatic levels. Because our study illustrates the primary role of diverse tectonic structures during massive multiphase cave development above and below the water table, it could contribute to better constraining of the models of karstic conduit formation.

  3. Geochemical evolution of groundwater in the carbonate aquifers of Sierra de Segura (Betic Cordillera, southern Spain)

    NASA Astrophysics Data System (ADS)

    Moral, F.; Cruz-Sanjulián, J. J.; Olías, M.

    2008-10-01

    SummarySierra de Segura (Betic Cordillera), with a total area of over 3000 km 2, is the source of the two principal rivers in southern Spain, the Guadalquivir and the Segura. Due to the orographic effect of these mountains, precipitations are considerably more abundant than in nearby lowland areas, where the climate is semi-arid. Sierra de Segura is constituted of Mesozoic and Cenozoic sedimentary rocks, among which there are thick limestone-dolomitic formations which have given rise to extensive outcrops of permeable materials. In geomorphological terms, there is a large plateau intensively karstified that constitutes the main recharge area. Discharge takes place via a large number of springs, of which the 50 most important add up to a mean spring flow of about 13,500 l/s. The active geochemical processes in aquifers of Sierra de Segura, with their corresponding time sequence, are: dissolution of CO 2, dissolution of calcite, incongruent dissolution of dolomite, dedolomitization, exsolution of CO 2, and precipitation of calcite. More evolved water has higher temperature, magnesium content and Mg/Ca ratio; therefore, these parameters can be utilised as indicators of the degree of hydrochemical evolution. In addition, a good correlation between water temperature and magnesium concentration (or Mg/Ca ratio) indicates that an increase in temperature accelerates the kinetics of the dissolution of dolomite. Finally, the distribution of the temperatures in the vadose zone, determined by atmospheric thermal gradient, implies an apparent stratification of the predominant hydrochemical processes and of the groundwater physical and chemical characteristics.

  4. Palaeomagnetic and kinematic constraints on deformation during oblique convergence, Betic Cordillera, southern Spain

    NASA Astrophysics Data System (ADS)

    Mayfield, Andrew Gilbert

    The Subbetic Zone is an external, unmetamorphosed, thin skinned fold-and-thrust belt of Alpine age, part of the Betic Cordillera, southern Spain. Miocene tectonics emplaced a 2 km pile of Mesozoic and Tertiary sediments north-westward onto Iberia. Previous palaeomagnetic studies have revealed differential vertical-axis rotations of 60° clockwise or more. Palaeomagnetic and structural studies in two study areas were undertaken with the aim of understanding how these large vertical-axis rotations accumulated in this obliquely convergent mountain belt, in the context of structures present. The El Chorro area, in the western Subbetic, is a 16 km2 structural culmination. Palaeomagnetic results show the imbricate thrust sequence has differential rotations within and between thrust sheets. It is likely folding, thrusting and rotation occurred close to the deformation front of the mountain belt. Vertical-axis rotation is attributed to a thrust sheet pinning mechanism. The Velez Blanco area covers approximately 400 km2 of the eastern Subbetic close to the Internal Zones. Structural analysis finds normal faults developed during Jurassic rifting. Rotation increases from zero to 60° clockwise from NE to SW, without abrupt changes across individual structures and correlates with a change in strike of thrust traces and stratigraphic contacts from N-S to almost E-W. This is suggestive of transcurrent shear in the more internal parts of the mountain belt. Thrust faults are mostly SSE-directed, but ESE-directed thrusting is common in the unrotated zone, suggesting that fault lineations indicative of transport directions have been rotated. Combined with strike-slip partitioning it is estimated that the local plate motion vector was N59°W, between the Alboran plate and Iberia. Two likely mechanisms were responsible for clockwise rotation in this region. 1) Early rotation during thrusting accumulated though the thrust sequence. 2) Transcurrent shear in the internal parts of the

  5. Remelting of Nanogranites in Peritectic Garnet from Granulites of Jubrique, Betic Cordillera, Southern Spain

    NASA Astrophysics Data System (ADS)

    Acosta-Vigil, A.; Barich, A.; Bartoli, O.; Poli, S.; Cesare, B.; Garrido, C. J.

    2014-12-01

    Peritectic minerals in migmatites can trap droplets of melt that form via incongruent melting during crustal anatexis. In most cases, these melts crystallize and form nanogranites upon slow cooling of the anatectic terrane. To obtain information on the primary compositions of crustal melts, nanogranites must be remelted and rehomogenized before analysis. A new occurrence of nanogranites was reported in granulitic gneisses at the bottom of the prograde metamorphic sequence of Jubrique, located on top of the Ronda peridotite slab (Betic Cordillera, S Spain). These nanogranites are trapped in garnet porphyroblasts. They show partially irregular to well facetted negative crystal shapes, and have variable size from ~5-10 μm and reach ~200 μm in diameter. They appear at the core and rim of large Grt crystals, and are composed of rare glass, daughter Qz, Pl, Kfs, Bt and Ms, and solid inclusions of Ky and less frequently Gr, Hc, Rt, Ilm, Zrn and Mnz. Ky was the main solid phase that favored the trapping of melt inclusions (MI) during Grt growth. The presence of Ky+Rt within MI, and their occurrence in the high-P cores of Grt, suggest that partial melting in the gneisses initiated at relatively high P conditions, and that most Grt in these rocks crystallized in the presence of melt. To recover the major and trace element composition of the primary melt during anatexis, we performed remelting experiments on chips of MI-bearing Grt separated from a sample of gneiss at Jubrique, using a piston cylinder apparatus. Experiments were run at 800, 825 and 850°C, 15 Kbar and dry conditions (i.e. no added H2O) for 24 hrs. Preliminary results of the first experiment at 850º show that nanogranites have been successfully remelted; they all contain glass regardless of their textural position. Glass is leucogranitic (SiO2≈65wt%; FeO+MgO≈2wt%), potassic (K#≈12), high in ASI (close to peraluminous) and hydrous (H2O≈11wt.%.). The degree of remelting, however, varies among

  6. The gold nuggets of the lower Pliocene Alhambra Formation (Betic Cordillera, Southern Spain)

    NASA Astrophysics Data System (ADS)

    Somma, Roberta; Bonvegna, Piero; Sanchez-Navas, Antonio

    2017-04-01

    The present research was devoted to the geochemical and textural characterization of gold nuggets extracted from auriferous siliciclastic deposits of the lower Pliocene continental Alhambra Formation (Betic Cordillera, Southern Spain). This Formation is mainly composed of metamorphic lithoclasts deriving both by the erosion of the Mulhacen Unit of the Nevado-Filabride Complex and the reworking of the upper Tortonian marine Dudar-Pinos Genil Formation, on its turn previously formed by erosion of the Veleta Unit of the Nevado-Filabride Complex. Particularly, the studied gold nuggets were separated from 1m3 of auriferous conglomerates sampled along the right side of the Genil River, in the abandoned Lancha de Cenes Mine, exploited since Roman time for gold mining. The recovered gold nuggets were 24 for a total weight of 0.125 g/m3. Textural analysis of gold nuggets was made by means mechanical sieving and visual comparison of roundness and form. They are sand-sized rounded to sub-rounded grains with spheroidal and cubic form. Surface analyses of the nuggets by SEM-EDS indicated that external portions show textures more porous than in the nuggets nuclei. Chemical analyses by EMPA indicated that they are constituted by pure gold with Ag and Hg as trace elements. The gold mine capacity of the studied auriferous deposits is at least of 0.125 g/m3 (lower than 0.5 g/m3; minimum value to be gold mine economically exploitable). Notwithstanding this value, the auriferous conglomerates of the Alhambra Formation reveal to be interesting under a gold mine exploitation point of view because of the gold high pureness degree. Finally, under a geological point of view, considering that the Alhambra Formation is mainly composed of lower Pliocene alluvial fan conglomerates and sandstones formed during the uplift of the Sierra Nevada, the selected gold nuggets are secondary deposits originally derived from primary deposits related to hydrothermal gold-bearing quartz veins included in

  7. Remelting of nanogranites in peritectic garnet from granulites of Jubrique, Betic Cordillera, Southern Spain

    NASA Astrophysics Data System (ADS)

    Barich, Amel; Bartoli, Omar; Acosta-Vigil, Antonio; Poli, Stefano; Cesare, Bernardo; Garrido, Carlos J.

    2014-05-01

    Peritectic minerals in migmatites can trap droplets of melt that form via incongruent melting reactions during crustal anatexis [1]. In most cases, these melts crystallize and form nanogranites upon slow cooling of the anatectic terrane [2]. To obtain information on the primary compositions of crustal melts, including volatile concentrations in melt and information on fluid regimes, nanogranites must be remelted and rehomogenized before analysis [3]. A new occurrence of nanogranites was recently reported in granulitic gneisses at the bottom of the prograde metamorphic sequence of Jubrique, located on top of the Ronda peridotite slab (Betic Cordillera, S Spain) [4]. These nanogranites are trapped in garnet porphyroblasts. They show partially irregular to well facetted negative crystal shapes, and have variable size from ~5-10 μm to several tens of μm or even ~200 μm in diameter. They appear at the core and rim of large Grt crystals, and are composed of rare glass, daughter Qz, Pl, Kfs, Bt and Ms, and solid inclusions of Ky and less frequently Gr, Hc, Rt, Ilm, Zrn and Mnz. Ky was the main solid phase that favored the trapping of melt inclusions (MI) by poisoning crystal surfaces during Grt growth. The presence of Ky+Rt within MI, and their occurrence in the high-P cores of Grt, suggest that partial melting in the gneisses initiated at relatively high P conditions, and that most Grt in these rocks crystallized in the presence of melt. To recover the major and trace element composition of the primary melt during anatexis, we performed remelting experiments on chips of MI-bearing Grt separated from a sample of gneiss at Jubrique, using a piston cylinder apparatus. Experiments were run at 800, 825 and 850° C, 15 Kbar and dry conditions (i.e. no added H2O) for 24 hrs. Preliminary results of the first experiment at 850º show that nanogranites have been successfully remelted; they all contain glass regardless of their textural position, i.e. at the core and rim of

  8. Seismicity pattern of the Betic Cordillera (Southern Spain) derived from the fractal properties of earthquakes and faults

    NASA Astrophysics Data System (ADS)

    Henares Romero, J.; López Casado, C.; Badal, J.; Peláez, J. A.

    2010-08-01

    Several studies on earthquake occurrence and associated faulting have demonstrated that both phenomena have a scale-invariant behavior which can be analyzed by means of a set of non-integer dimensions ( D q ) describing their fractal properties and the calculation of multi-fractal spectra. It is the case that the behavior of these spectra is asymptotic at the ends of the variation interval of q, which is a real number that enters into the definition of the partition function of the dataset. The difference between the extreme values, called multi-fractal spectrum slope, is used to investigate the heterogeneity of the spatial distribution of earthquakes and fault systems. In this paper we focus on the Betic Cordillera, southeastern Spain, which is commonly considered the contact between the Eurasian and African plates and has an important seismic activity in the context of the Iberian Peninsula. Some of the most conspicuous Iberian earthquakes, such as the 1829 m b6.3 Torrevieja and the 1884 m b6.1 Alhama de Granada earthquakes occurred in this mountain range and both reached intensity X. The present work implies a new analysis based on the slope of multi-fractal spectra and referred to the historical seismicity of the region, specifically b-value (frequency distribution of earthquakes respect to magnitude), epicentral location, seismic energy and faulting. On this basis we propose a seismotectonic zonation that is contrasted with the stress state and the geodynamical evolution of the Betic Cordillera.

  9. Faulted hybrid joints: an example from the Campo de Dalias (Betic Cordilleras, Spain)

    NASA Astrophysics Data System (ADS)

    Marín-Lechado, Carlos; Galindo-Zaldívar, Jesús; Rodríguez-Fernández, Luís. Roberto; González-Lodeiro, Francisco

    2004-11-01

    The development of hybrid and faulted joints has not been studied in detail in natural outcrops. This field study in the Campo de Dalias (Betic Cordilleras) establishes the distinctive features of these structures as compared with those predicted by theoretical studies. Hybrid joints appear as two sets of vertical joints forming variable angles, but generally about 25°, with opening directions orthogonal to joint planes. Their development requires low differential stresses with a tensile minimum stress. The main criteria that indicate the existence of faulted joints are: (1) the presence of subvertical fault planes with oblique slip forming a complex pattern of dextral and sinistral faults developed under a single stress regime; (2) faults with similar geometries as joints in the same outcrop, showing an inconsistent cross-cutting relationship; and (3) the development of small basins with variable polarity of asymmetric wedge filling. A permutation in stress orientation since the Tortonian in the Campo de Dalias was responsible for the development of a faulted hybrid joint system, with a constant ENE-WSW extension trend and a switch of σ1 between NNW-SSE and vertical.

  10. East-west thrusting and anomalous magnetic declinations in the Sierra Gorda, Betic Cordillera, southern Spain

    NASA Astrophysics Data System (ADS)

    Platzman, E. S.

    1994-01-01

    Structural and palaeomagnetic studies in the Sierra Gorda (Sierra de Loja), located in the External zone of the Betic Cordillera, indicate that westward-directed thrusting is not associated with significant rotations about a vertical axis. Detailed mapping and slip vector analysis show that the Sierra Gorda is a thrust complex composed of three thrust sheets. The uppermost thrust places Early Jurassic pelagic carbonates on top of Jurassic to Oligocene sediments that form a large doubly-plunging footwall syncline. The eastern limb of this syncline has been overturned and is tectonically thinned as a result of the overthrusting. Palaeomagnetic results from Mesozoic and Tertiary sediments both within and around the perimeter of the Sierra Gorda indicate that: (1) the average remanence vector of the seven Late Jurassic localities sampled within the Sierra Gorda has a direction (D = 328° and I = 38°) that is not significantly different from the expected declination for the Upper Jurassic of stable Iberia; and (2) there is no significant difference between the remanences in the two upper thrust sheets indicating that differential rotation did not occur during the initiation and displacement on the thrusts. In contrast, the one Late Jurassic site that was sampled to the west of the Sierra Gorda is rotated, like the rest of the Subbetics, 60° clockwise of the reference direction. The unrotated directions obtained in the Sierra suggest, either that it has rotated in a clockwise sense concordant with the rest of the Subbetic zone and has then been backrotated, or that it has never rotated relative to stable Iberia. In the latter, simpler hypothesis the unrotated declinations may be explained in terms of orthogonal convergence along an irregular continental margin.

  11. Two Tertiary metamorphic events recognized in metapelites of the Nevado-Filabride Complex (Betic Cordillera, S Spain)

    NASA Astrophysics Data System (ADS)

    Li, Botao; Massonne, Hans-Joachim

    2017-04-01

    The orogenic belt of the Betic Cordillera in southern Spain resulted from the collision of the African plate with the southwestern edge of the Eurasian plate in Alpine times. This belt can be considered as a large nappe stack with the Nevado-Filabride Complex in the eastern Betic Cordillera representing the lowest nappe, in which high-pressure (HP > 10 kbar) rocks such as eclogites occur. We have studied two metapelites from the Ragua (former Veleta) unit, which is the lowest unit of the Nevado-Filabride Complex. These rocks were sampled at Cerro de los Machos (sample 23085) and c. 3 km east of this locality at the Laguna de la Caldera (sample 23098) and contain quartz, potassic white-mica, paragonite, chlorite, garnet, biotite, tourmaline, epidote, rutile, ilmenite, apatite, zircon and monazite and titanite (23085) or calcite and albite (23098). Garnet in both rocks is similarly zoned. An inclusion-rich core shows a prograde metamorphic zonation with high and low Mn contents in the center (e.g. for 23085: Alm64.5Grs27Py2.5Sps6) and at the rim (Alm84Grs8Py6Sps2), respectively, of the core domain. After corrosion of this domain a garnet mantle formed with an inner zone being again relatively rich in Mn and an outermost rim being poor in Mn. This mantle is significantly richer in Mg and poorer in Ca compared to the core domain. Potassic white-mica in the samples also shows a considerable compositional spread (Si = 3.05-3.20 in 23085 and 3.13-3.33 in 23098) with the highest Si contents in the core of potassic white-mica grains. To elucidate the metamorphic evolution of the rocks we calculated various P-T pseudosections for different H2O-CO2 contents and Fe3+/Fe2+ ratios with PERPLE_X. On the basis of the compositions of the garnet inner core and the highest Si content in potassic white mica contrasting peak pressures at c. 535˚ C resulted for the rocks (23085: 12.8 kbar, 23098: 18.3 kbar). A subsequent pressure release to about 8 (23085) or 5 kbar (23098) at slightly

  12. Sequence model for coastal-plain depositional systems of the Upper Triassic (Betic Cordillera, southern Spain)

    NASA Astrophysics Data System (ADS)

    Pérez-López, A.

    1996-01-01

    The deposits of the Upper Triassic of the Subbetic Zone (Betic Cordillera) offer an example of semi-arid fluvial deposits passing into shallow-water facies through a mud-flat environment. From the study of the vertical changes in facies, a sequence model is proposed for the Upper Triassic succession, relating, for each systems tract, the changes in sea level, the accommodation space and the evolution of the facies within a coastal-plain depositional system. The lowstand depositional system is made up of a package of thick, amalgamated sandstone strata limited below by an erosive surface with little incision. These are sheet-flood deposits and channel fills which form part of an extensive alluvial system in which wide but shallow water courses appear, with the development of extensive sand bars. These sandbodies from the lowstand phase often contain mudrock intraclasts, plant remains and erosive surfaces. The accommodation space being extremely limited, the preservation of the floodplain or mud-flat deposits and palaeosols is practically nil. The result is an amalgamation of extensive sandbodies with fine intercalated claystone levels. The transgressive depositional systems consist mainly of a red claystone series, although the first sediments of these systems are composed of sandstone with major claystone intercalations. These lower sandy levels of the transgressive phase do not exceed 50 cm in thickness and usually contain burrows and small-scale sedimentary structures. In the intermediate part of the red claystone series of this transgressive episode of saline mud-flat facies, there are sandstone levels of a little-developed fluvial system with channels which migrate laterally due to the rise of the base level. In addition, the predominance and the great development of the red claystone facies reflect the increase in the accommodation space, which permitted a greater accumulation of sediments during a transgressive phase than during the lowstand phase. In the

  13. Ichnological analysis in high-resolution sequence stratigraphy: The Glossifungites ichnofacies in Triassic successions from the Betic Cordillera (southern Spain)

    NASA Astrophysics Data System (ADS)

    Rodríguez-Tovar, Francisco J.; Pérez-Valera, Fernando; Pérez-López, Alberto

    2007-06-01

    This study integrates ichnological and sedimentological data in order to refine sequence stratigraphy and interpretations of sea-level dynamics for the Ladinian (Middle Triassic), Muschelkalk succession (Siles Formation) in the Betic Cordillera (southern Spain). Facies analysis was integrated with a detailed ichnological study, focused on the middle part of the lower member of the Muschelkalk succession (transgressive systems tract), which is characterized by an abundant and conspicuous trace fossil assemblage. Seven lithofacies were recognized, recording sediment accumulation in tidal flat, and inner to outer marine carbonate ramp, depositional environments. Thin-bedded marly limestones with bioclastic shelly beds (Facies E: middle ramp, with storm influence), are characterized by Diplocraterion and Rhizocorallium. Diplocraterion is protrusive, usually eroded on top, and mainly recorded in the marly limestone intervals. Rhizocorallium preserves well defined scratch-marks, and is commonly emplaced in bioclastic, shelly beds. The assemblage represents the Glossifungites ichnofacies. Sedimentological and ichnological data are interpreted to record a complex transgressive context, associated with high-frequency sea-level dynamics that allowed formation of transgressive surfaces of erosion (TSE, i.e., ravinement surfaces) of different orders. Major TSE, associated with continuous bioclastic shelly beds, delimit parasequences; the absence of the Glossifungites suite reveals that there was little time between erosion and deposition. Intermediate TSE, associated with discontinuous shell beds, are related to comparatively less significant sea-level rises and occur within parasequences. The Glossifungites suite reveals colonization of firmgrounds during relatively prolonged times between erosion and deposition related to intermediate TSE. Minor order TSE, recorded between the intermediate TSE, are related to punctuated, highest frequency sea-level changes; phases of

  14. Recent seismogenic fault activity in a Late Quaternary closed-lake graben basin (Albacete, SE Spain)

    NASA Astrophysics Data System (ADS)

    Rodríguez-Pascua, M. A.; Pérez-López, R.; Calvo, J. P.; García del Cura, M. A.

    2008-11-01

    The Cordovilla basin, located within the frontal thrust belt of the Betic Cordillera, SE Spain, is an elongated NW-SE graben showing discrete surface rupture generated by Holocene paleoearthquake activity. A main and an antithetic normal, NW-SE trending, active faults bound the basin. Paleoseismological evidence is reported on upslope-facing scarps of the antithetic fault, acting as dams to runoff, which contributed to temporary lacustrine conditions, as well as sediment uplift. The fluvial network in the area shows a poor drainage activity, whereas a present lake is dammed by the antithetic fault. The modern landscape is controlled by Holocene faulting, modifying the geological environment according to earthquake occurrence, from flat alluvial plains to lacustrine local basins. The application of the diffusion dating technique to unconsolidated sediments for the antithetic fault scarp indicates an age between 1 and 2 ka. Various geometric parameters have been obtained in order to reconstruct the paleoseismic history of the Cordovilla graben basin. The surface rupture and fault-offset values are associated with discrete active morpholineaments, parallel to the Pozohondo Fault. The Tobarra-Cordovilla segment (the structural boundary of the Cordovilla Basin) was generated by earthquakes with magnitudes (Mw) greater than 6.0, based on Wells and Coppersmith fault scarp relations.

  15. Isotopic composition of Pb in ore deposits of the Betic Cordillera, Spain; origin and relationship to other European deposits

    USGS Publications Warehouse

    Arribas , Antonio; Tosdal, Richard M.

    1994-01-01

    The Betic Cordillera in southern Spain is a complex Alpine fold belt that resulted from the Cretaceous through Cenozoic collision of Africa with Europe. The region is illustrative of one of the characteristics of the Alpine-Mediterranean orogen: the occurrence over a limited area of mineral deposits with a wide variety of host rocks, mineralization ages, and styles. The metamorphic basement in the Betic zone is characterized by a nappe structure of superimposed tectonostratigraphic units and consists of lower Paleozoic to Lower Triassic clastic metasedimentary rocks. This is overlain by Middle to Upper Triassic platform carbonate rocks with abundant strata-bound F-Pb-Zn-(Ba) deposits (e.g., Sierra de Gador, Sierra Alhamilla). Cretaceous to Paleogene subduction-related compression in southeastern Spain was followed by Miocene postcollisional extension and resulted in the formation of the Almeria-Cartagena volcanic belt and widespread hydrothermal activity and associated polymetallic mineralization. Typical Miocene hydrothermal deposits include volcanic-hosted Au (e.g., Rodalquilar) and Ag-rich base metal (e.g., Cabo de Gata, Mazarron) deposits as well as complex polymetallic veins, mantos, and irregular replacement bodies which are hosted by Paleozoic and Mesozoic metamorphic rocks and Neogene sedimentary and volcanic rocks (e.g., Cartagena, Sierra Almagrera, Sierra del Aguilon, Loma de Bas).Lead isotope compositions were measured on sulfide samples from nine ore districts and from representative fresh samples of volcanic and basement rock types of the region. The results have been used to evaluate ore-forming processes in southeastern Spain with emphasis on the sources of metals. During a Late Triassic mineralizing event, Pb was leached from Paleozoic clastic metasedimentary rocks and incorporated in galena in strata-bound F-Pb-Zn-(Ba) deposits ( 206 Pb/ 204 Pb = 18.332 + or - 12, 207Pb/ 204 Pb = 15.672 + or - 12, 208 Pb/ 204 Pb = 38.523 + or - 46). The second

  16. Emplacement of the Cabezo María lamproite volcano (Miocene, SE Spain)

    NASA Astrophysics Data System (ADS)

    Gernon, Thomas M.; Spence, Samuel; Trueman, Clive N.; Taylor, Rex N.; Rohling, Eelco; J. Hatter, Stuart; Harding, Ian C.

    2015-06-01

    Lamproite volcanoes are uncommon in the geological record but are exceptionally well preserved in the Betic Cordilleras of SE Spain, where they erupted during the Late Miocene (Tortonian to Messinian stages). The parent melts are thought to have been channelled through major lithospheric faults to erupt at or near the faulted margins of Neogene sedimentary basins. Lamproite magmas are thought to be relatively CO2-poor (<1 wt %) and are typically characterised by an effusive eruption style and the development of lava lakes and scoria cones. Cabezo María is a relatively small (˜550 m diameter) lamproite volcano that was emplaced within the shallow-water marine-influenced Vera Basin. The lamproites are compositionally similar to those of the Roman Province and generally less potassic (K2O<5 wt%) than other (ultra-) potassic rocks in SE Spain (e.g. Cancarix, Fortuna). The initial eruption stages were dominated by explosive magma-water interactions and the formation of peperites. These are characterised by angular fragments of glassy lamproite lavas (and isolated lobes) incorporated in sediments, locally showing the effects of thermal metamorphism. Further, elutriation pipes and `jigsaw-fit' textures are observed in the peperites. The lavas and peperites are overlain by outward-dipping well-stratified scoria deposits defining part of a cinder cone, which is inferred to have emerged above sea level. Steep internal contacts with inward-dipping, structureless breccias likely represent the inner wall deposits of a central conduit. The deposits are cross-cut by late-stage dykes, which supplied fissure eruptions of geochemically similar lavas capping the scoria cone. The transition from explosive to effusive behaviour may reflect the decreased availability of water, possibly due to downward migration of the feeder conduit below the level of water-saturated sediments.

  17. Microstructures and Petrology of Melt Inclusions in the Anatectic Sequence of Jubrique (Betic Cordillera, S Spain): Implications for Crustal Anatexis

    NASA Astrophysics Data System (ADS)

    Acosta-vigil, A.; Barich, A.; Garrido, C. J.; Cesare, B.; Tajčmanová, L.; Bartoli, O.

    2014-12-01

    We report a new occurrence of melt inclusions in polymetamorphic granulitic gneisses of the Jubrique unit, a complete though thinned crustal section located above the Ronda peridotite slab (Betic Cordillera, S Spain). The gneissic sequence is composed of mylonitic gneisses at the bottom and porphyroblastic gneisses on top. Mylonitic gneisses are strongly deformed rocks with abundant garnet and rare biotite. Except for the presence of melt inclusions, microstructures indicating the former presence of melt are rare or absent. Upwards in the sequence garnet decreases whereas biotite increases in proportion. Melt inclusions are present from cores to rims of garnets throughout the entire sequence. Most of the former melt inclusions are now totally crystallized and correspond to nanogranites, whereas some of them are partially made of glass or, more rarely, are totally glassy. They show negative crystal shapes and range in size from ≈5 to 200 micrometers, with a mean size of ≈30-40 micrometers. Daughter phases in nanogranites and partially crystallized melt inclusions include quartz, feldspars, biotite and muscovite; accidental minerals include kyanite, graphite, zircon, monazite, rutile and ilmenite; glass has a granitic composition. Melt inclusions are mostly similar throughout all the gneissic sequence. Some fluid inclusions, of possible primary origin, are spatially associated with melt inclusions, indicating that at some point during the suprasolidus history of these rocks granitic melt and fluid coexisted. Thermodynamic modeling and conventional thermobarometry of mylonitic gneisses provide peak conditions of ≈850 ºC and 12-14 kbar, corresponding to cores of large garnets with inclusions of kyanite and rutile. Post-peak conditions of ≈800-850 ºC and 5-6 kbar are represented by rim regions of large garnets with inclusions of sillimanite and ilmenite, cordierite-quartz-biotite coronas replacing garnet rims, and the matrix with oriented sillimanite. Previous

  18. Microstructures and petrology of melt inclusions in the anatectic sequence of Jubrique (Betic Cordillera, S Spain): Implications for crustal anatexis

    NASA Astrophysics Data System (ADS)

    Barich, Amel; Acosta-Vigil, Antonio; Garrido, Carlos J.; Cesare, Bernardo; Tajčmanová, Lucie; Bartoli, Omar

    2014-10-01

    We report a new occurrence of melt inclusions in polymetamorphic granulitic gneisses of the Jubrique unit, a complete though strongly thinned crustal section located above the Ronda peridotite slab (Betic Cordillera, S Spain). The gneissic sequence is composed of mylonitic gneisses at the bottom and in contact with the peridotites, and porphyroblastic gneisses on top. Mylonitic gneisses are strongly deformed rocks with abundant garnet and rare biotite. Except for the presence of melt inclusions, microstructures indicating the former presence of melt are rare or absent. Upwards in the sequence, garnet decreases whereas biotite increases in modal proportion. Melt inclusions are present from cores to rims of garnets throughout the entire sequence. Most of the former melt inclusions are now totally crystallized and correspond to nanogranites, whereas some of them are partially made of glass or, more rarely, are totally glassy. They show negative crystal shapes and range in size from ≈ 5 to 200 μm, with a mean size of ≈ 30-40 μm. Daughter phases in nanogranites and partially crystallized melt inclusions include quartz, feldspars, biotite and muscovite; accidental minerals include kyanite, graphite, zircon, monazite, rutile and ilmenite; glass has a granitic composition. Melt inclusions are mostly similar throughout all the gneissic sequence. Some fluid inclusions, of possible primary origin, are spatially associated with melt inclusions, indicating that at some point during the suprasolidus history of these rocks granitic melt and fluid coexisted. Thermodynamic modeling and conventional thermobarometry of mylonitic gneisses provide peak conditions of ≈ 850 °C and 12-14 kbar, corresponding to cores of large garnets with inclusions of kyanite and rutile. Post-peak conditions of ≈ 800-850 °C and 5-6 kbar are represented by rim regions of large garnets with inclusions of sillimanite and ilmenite, cordierite-quartz-biotite coronas replacing garnet rims, and the

  19. Benthic foraminiferal biostratigraphy of the Aalenian-Bajocian (Middle Jurassic) boundary in the Barranco de Agua Larga section (Betic Cordillera, southern Spain)

    NASA Astrophysics Data System (ADS)

    Silva, Sílvia; Canales, María Luisa; Sandoval, José; Henriques, Maria Helena

    2016-04-01

    This work describes the benthic foraminiferal assemblages recorded across the Aalenian - Bajocian boundary in the Barranco de Agua Larga section (Betic Cordillera, SE of Spain), where the ammonite record has enabled the recognition of the Gigantea Subzone in the Bradfordensis Zone (Middle Aalenian), the Concavum and Limitatum subzones in the Concavum Zone (Upper Aalenian) and the Discites Zone (Lower Bajocian). This reference section is characterized by an alternation of limestones and marly limestones corresponding to distal marine environmental conditions, where a total of 17 samples have been collected. They have provided abundant and diverse foraminiferal assemblages, constituted by well-preserved specimens displaying close similarities to those already described for the Jurassic carbonate platforms of the Boreal Realm. From the study of the samples, a total of 3139 specimens have been obtained, corresponding to 5 suborders, 11 families, 25 genus and 80 species. The representatives of the Suborder Lagenina are the most abundant, Vaginulinidae is the most abundant family and Lenticulina is the most abundant genus. From a specific level, the most abundant species are Thurammina jurensis (Franke), Lenticulina muensteri (Roemer) and Prodentalina pseudocommunis (Franke). The occurrence of Astacolus dorbignyi (Roemer) in the Gigantea Subzone has enabled the recognition of the Astacolus dorbignyi Zone. The first occurrence of Lenticulina quenstedti (Gümbel) in the Concavum Subzone has allowed the recognition of the Lenticulina quenstedti Zone. In Barranco de Agua Larga section this species co-occur with Ramulina spandeli Paalzow, the index fossil used in the establishment of the Ramulina spandeli Zone. This zone was defined in the lower part of the Discites Zone in the Murtinheira section (the Bajocian GSSP) and related to distal platform conditions. In the Iberian Basin the Ramulina spandeli Zone was recognized in the Hontoria del Pinar section, but not in the

  20. Seismic transpressive basement faults and monocline development in a foreland basin (Eastern Guadalquivir, SE Spain)

    NASA Astrophysics Data System (ADS)

    Pedrera, A.; Ruiz-Constán, A.; Marín-Lechado, C.; Galindo-Zaldívar, J.; González, A.; Peláez, J. A.

    2013-12-01

    We examine the late Tortonian to present-day deformation of an active seismic sector of the eastern Iberian foreland basement of the Betic Cordillera, in southern Spain. Transpressive faults affecting Paleozoic basement offset up to Triassic rocks. Late Triassic clays and evaporites constitute a décollement level decoupling the basement rocks and a ~100 m thick cover of Jurassic carbonates. Monoclines trending NE-SW to ENE-WSW deform the Jurassic cover driven by the propagation of high-angle transpressive right-lateral basement faults. They favor the migration of clays and evaporites toward the propagated fault tip, i.e., the core of the anticline, resulting in fluid overpressure, fluid flow, and precipitation of fibrous gypsum parallel to a vertical σ3. The overall geometry of the studied monoclines, as well as the intense deformation within the clays and evaporites, reproduces three-layer discrete element models entailing a weak middle unit sandwiched between strong layers. Late Tortonian syn-folding sediments recorded the initial stages of the fault-propagation folding. Equivalent unexposed transpressive structures and associated monoclines reactivated under the present-day NW-SE convergence are recognized and analyzed in the Sabiote-Torreperogil region, using seismic reflection, gravity, and borehole data. A seismic series of more than 2100 low-magnitude earthquakes was recorded within a very limited area of the basement of this sector from October 2012 to May 2013. Seismic activity within a major NE-SW trending transpressive basement fault plane stimulated rupture along a subsidiary E-W (~N95°E) strike-slip relay fault. The biggest event (mbLg 3.9, MW 3.7) occurred at the junction between them in a transpressive relay sector.

  1. Accidents in the greenhouse-construction industry of SE Spain.

    PubMed

    Pérez-Alonso, José; Carreño-Ortega, Angel; Vázquez-Cabrera, Fernando J; Callejón-Ferre, Angel Jesús

    2012-01-01

    This work analyses the labour accidents in the greenhouse-construction industry of SE Spain for the period 1999-2007 through a sample of 180 accident reports. The accidents were characterised by studying 5 variables in order to know the day of the week in which the accident occurred, the hour of the day of the accident, type of accident, the region of Spain in which the accident happened, and the resulting injury. The data characterising the accidents were submitted to a descriptive multiple-correspondence analysis. The incidence of accidents in the greenhouse-construction industry presented a high mean value of 15133.7 per 100,000 workers per year. The days with the greatest incidence of accidents were Thursday and Monday, while the period of greatest number of accidents occurred in the first 4h of the workday. No significant correspondence was found between the day of the week, the hour of the day, or any of the other 3 variables studied. The types of accidents with most frequency were: cuts, punctures, contact with hard or rough material, overexertion, and falls from one level to another. The most affected parts of the anatomy were the eyes, thorax, back, sides, lower legs, and feet. The most common types of injury were bone fractures, twists and sprains, distended muscles, contusions, and being crushed. The study calls attention to the high number of accidents at work, which needs to be corrected by fulfilment of safety regulations at work, on the part of the company. Finally, recommendations are made to correct this situation of high number of accidents at work. Copyright © 2011 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  2. The Eastern delta-fan deposits on the Granada Basin as tectonic indicators of the Sierra Nevada uplift (Betic Cordillera, South Spain)

    NASA Astrophysics Data System (ADS)

    Roldán, Francisco Javier; Azañon, Jose Miguel; Mateos, Rosa Maria

    2014-05-01

    Sierra Nevada uplift and with original NE-SW normal left-lateral fault system associated with a compatible ESE-WNW normal fault system. The asymmetrical morphologies of the two delta-fan bodies confirm this configuration as tectonic induced deposits. References Braga, J.C., Martín, J.M. and Alcalá, B. (1990). Coral reefs in coarse-terrigenous sedimentary environments (Upper Tortonian, Granada Basin, southern Spain). Sedimentary Geology, 66, pp 135-150. Clark, S.J.P.and Dempster, T.J. (2009). The record of tectonic denudation and erosion in an emerging orogen: an apatite fission-track study of the Sierra Nevada, southern Spain. Journal of the Geological Society, London, Vol. 166, pp. 87-100. Dabrio, C.J., Fernández, J., Peña, J., Ruíz-Bustos, A. y Sanz de Galdeano, C. (1978). Rasgos sedimentarios de los conglomerados miocénicos del borde noreste de la Depresión de Granada. Estudios Geológicos, 34, pp 89-97. García-García, F., Fernández, J., Viseras, C. and Soria, J.M. (2006). Architecture and sedimentary facies evolution in a delta stack controlled by fault growth (Betic Cordillera, southern Spain, late Tortonian). Sedimentary Geology, 185, pp. 79-92. García-García, F., Viseras, C. and Fernández, J. (1999). Organización secuencial de abanicos deltaicos controlados por la tectónica (Tortoniense superior, cuenca de Granada, Cordillera Bética). Rev. Soc. Geol. España, 12 (2): 199-208.

  3. 3D reconstruction of a normal fault zone: A trenching study on a strand of the active Baza fault, Central Betic Cordillera, south central Spain

    NASA Astrophysics Data System (ADS)

    Koch, Leah Jean; Cardozo, Nestor; Martin-Rojas, Iván; Alfaro, Pedro; Castro, Julia; Medina-Cascales, Iván; García-Tortosa, Francisco J.

    2017-04-01

    Faults are rarely a discrete two-dimensional surface, but a three dimensional volume with a complex internal structure. Faults are commonly encountered in reservoirs and evaluated for their ability to act as a fluid flow conduit or barrier. The problem is that the structure of a fault zone in 3D is poorly understood, particularly because outcrops exposing fault zones in 3D are rare, and few have a large (e.g. 100 m) throw. Detailed 3D outcrop studies of fault zones can help provide insight into their internal structure, and the processes undergone during faulting, as well as improve the predictability of subsurface (e.g. reservoir) models. The main objective of this project is to construct a 3D structural model of a strand of the Baza fault, an active normal fault located in south central Spain in the Betic Cordillera. This strand is one of the many strands of the Baza fault system, and has an estimated throw of 30 meters in a relatively unconsolidated clay to silt Pliocene sequence. Through a trenching study, 10 vertical dip sections, 3 vertical strike sections, and one depth section in an area of approximately 80 m2 were excavated, cleaned, Lidar scanned, photographed, and documented. Based on these sections, we have reconstructed the 3D geometry and associated structures of this superb fault zone. These data can be used to study the variability of fault zones in 3D, but also for geophysical (e.g. seismic imaging) and reservoir modeling studies.

  4. Tectonic control in the boundaries of the genetic units: an example in the Dogger of the External Zones of the Betic Cordillera (province of Murcia and Almeria, Spain)

    NASA Astrophysics Data System (ADS)

    Rey, J.

    1995-02-01

    I have studied the evolution of a genetic unit of the Dogger to the north of Vélez-Rubio (External Zones of the Betic Cordilleras, southeast Spain). This unit, at its lower and upper boundaries, is limited by sedimentary breaks of the uppermost Toarcian and intra-upper Bathonian, respectively. Starting from the analysis and distribution of facies (rich in ostracods, oncolites, oolites, crinoids, peloids, pelagic pelecypods or deposited particles) on diverse drawn columns, the lateral and vertical evolution in this section of the basin for this period of time can be deduced. This permits the differentiation between systems tracts (lowstand systems tract, LST; transgressive systems tract, TST; and highstand systems tract, HST) with a slightly homogeneous distribution, which can be related to an uneven morphology of the substratum. Different factors that controlled the evolution of the basin during this period of time have been analysed; from this we can deduce that the role of tectonics could be dominant as contrasted with that of eustasy. An anomalous evolution toward the top of the highstand systems tract is indicated. In this unusually thick succession some evidence of retrogradation can be deduced. This could not be explained eustatically but it could certainly be explained tectonically.

  5. Metasedimentary and igneous xenoliths from Tallante (Betic Cordillera, Spain): Inferences on crust-mantle interactions and clues for post-collisional volcanism magma sources

    NASA Astrophysics Data System (ADS)

    Bianchini, Gianluca; Braga, Roberto; Langone, Antonio; Natali, Claudio; Tiepolo, Massimo

    2015-04-01

    The deep seated xenolith association exhumed in the Pliocenic volcano of Tallante (Betic Cordillera, Spain) includes protogranular mantle peridotites, felsic (metasedimentary) crustal rocks, as well as cumulus igneous rocks such as norites and amphibole (± phlogopite)-clinopyroxenites. The whole xenolith suite equilibrated at the same pressure (0.7-0.9 GPa) representing the local crust-mantle boundary (MOHO) characterized by extreme lithological heterogeneity. This heterogeneity resulted from orogenic processes that induced the juxtaposition of crustal rocks (variably depleted in fusible components) within mantle domains including metasomes, as it is commonly observed in orogenic mantle massifs of the Mediterranean area. In this contribution, we report new mineral compositions of igneous parageneses recorded in these xenoliths, and we present Sr-Nd isotope data on both igneous and metasedimentary xenoliths that integrate those from the literature. Sr-Nd isotopes coherently indicate a restitic character of the metasedimentary xenoliths, which according to model ages were affected by partial melting in Paleozoic times. Sr-Nd isotopic errorchrons on the igneous xenoliths, on the other hand, qualitatively indicate Tertiary ages, which are corroborated by U-Pb zircon datings of one norite xenolith and two composite xenoliths having zircon-bearing norite veinlets. The new data are discussed proposing that MOHO lithologies of Tallante could provide significant source compositions for the genesis of the Neogene volcanics of the Betic area, which included calcalkaline lavas as well as more potassic products such as lamproites.

  6. Testing the sensitivity of geomorphic indices in areas of low-rate active folding (eastern Betic Cordillera, Spain)

    NASA Astrophysics Data System (ADS)

    Pedrera, Antonio; Pérez-Peña, José Vicente; Galindo-Zaldívar, Jesús; Azañón, José Miguel; Azor, Antonio

    2009-04-01

    Active deformation structures have an incidence in topography that can be quantified by using geomorphic indices. Most of these indices have been checked in faulted regions with high-deformation rates. The application of several geomorphic indices (hypsometric curve analysis, normalized stream-length gradient, and valley width-to-valley height ratio) to the drainage network of the southern limb of the Sierra de Las Estancias antiform (Internal Zones, eastern Betic Cordillera), where low-rate active folding has been recognized, allows us to investigate the suitability of these indices to identify active structures in such a scenario. Hypsometric curves clearly identify regions with recent uplift and young topography, but they do not provide any constraint on the location of active folds. Local valley width-to-valley height index variations have been detected just coinciding whit the position of ENE-WSW active folds. Normalized stream-length gradient index serves to locate active folds in areas of hard rock substratum, but not in those areas with soft sediments (Neogene-Quaternary sedimentary basins). This is most likely due to the fact that in the basins erosion is much more intense than in the hard rock sectors. In view of these results, we consider that geomorphic indices constitute a valuable tool for identifying sectors affected by low-rate uplift related to active folding, with the best results obtained in hard rock areas.

  7. The role of western Mediterranea tectonic evolution in the geometry of a karstic domain in the Betic Cordilleras (Sierra Gorda, Spain): Importance of a tardy extensional regime

    NASA Astrophysics Data System (ADS)

    Pistre, Séverin; Lopez-Chicano, Manuel; Pulido-Bosch, Antonio; Drogue, Claude

    1999-01-01

    Located in the central part of the Betic Cordilleras, the large carbonate Sierra Gorda Massif provides an example of a west-Mediterranean karstic aquifer. In spite of a complex polyphased tectonic history, the fracturing presents, from aerial views and at outcrop scale a quite organised geometry. Four fracture directions are found over the massif: N000-010, N050-070, N090-100 and N140-170. The statistical and geostatistical approach allows the characteristics (lengths, orientations) and the spatial structure for each fracture set to be determined. The NOOO-010 and N140-170 sets are grouped in packets whereas the two other sets are grouped in bands. The microtectonic study describes the evolution of the massif in the geodynamic context of this part of Mediterranea, distinguishing three recent stages of brittle tectonic activity in the massif: a WNW-ESE Middle Miocene compression, then a NNW-SSE to NW-SE compression with a poorly wrenching regime, and finally a probably pre-Quaternary N-S radial distension. This last stage is essential for the karstification of the massif and groundwater circulation. From the combined analysis of fracture network geometry and palaeostresses a multiple porosity model in agreement with hydrological observations made inside the massif can be proposed: in particular, the hectometric N090-100 (and N050-070) fractures which are essential for the network connectivity, and have a major drainage role at aquifer scale, while the N000-010 and N140-170 ones have a more local drainage role. This extensive tardy regime, which is for the first time described separately from the internal zones of the Cordilleras, must be considered as a significant phenomenon on a regional scale, and henceforth integrated in future geodynamic schemes of this part of Mediterranea.

  8. Extensional Detachment faulting in melange rocks. Plurikilometres migration by W the External Zone (Cordillera Bética, Spain)

    NASA Astrophysics Data System (ADS)

    Roldán, Francisco Javier; Azañon, Jose Miguel; Rodríguez, Jose; Mateos, Rosa Maria

    2014-05-01

    The synthesis and correlation of units carried out in the continuous geological map (Roldán et al., 2012), has revealed a fragmentation of the carbonate outcrops belong to the Subbetic Domain (García-Hernández et al., 1980). Subbetic NW verging thrust and fold axial traces have not lateral continuity and Jurassic carbonate outscrops appear as klippes on the olistotromic unit. These ductile structures that can be observed in the internal structure of these jurassic blocks are unrelated to the brittle-ductile deformation bands observed at the basal pelitic levels. Basal detachments are rooted in: a) the Olistostromic unit, a Upper Langhian-Lower Serravallian breccia constituted by gypsum-bearing clay and marls; b) Cretaceous-Tertiary marly sedimentary rocks (Rodríguez-Fernández, et al., 2013) . In both kind of rocks, cataclastic structures allows to infer a top-to-the WSW displacement. Paleostress measurements, made on these detachments levels, are compatible with a extensional regime (Roldán et al., 2012). At the same time, the analysis and interpretation of subsurface data (seismic surveys and borehole testing) shows that the Subbetic Domain (External Subbetic, Molina 1987) are affected by westward low-angle normal faults. A balanced cross-section, based on morphological and cartographic data in the area between Sierra de Cabra and Sierra de Alta Coloma (Valdepeñas de Jaén), shows plurikilometric displacements which has been produced during Late Serravallian-Early Tortonian times. References: García-Hernández, M., López-Garrido, A.C., Rivas, P., Sanz de Galdeano, C., Vera, J.A. (1980): Mesozoic paleogeographic evolution of the zones of the Betic Cordillera. Geol. Mijnb. 59 (2). 155-168. Molina, J.M. (1987). Análisis de facies del Mesozoico en el Subbético. Tesis Doctoral, Univ. Granada. 518 p. Rodríguez-Fernández, J., Roldán, F. J., Azañón, J.M. y García-Cortés, A. (2013). El colapso gravitacional del frente orogénico a lpino en el Dominio Subb

  9. Quantitative subsidence-uplift analysis of the Bajo Segura Basin (eastern Betic Cordillera, Spain): tectonic control on the stratigraphic architecture

    NASA Astrophysics Data System (ADS)

    Soria, J. M.; Alfaro, P.; Fernández, J.; Viseras, C.

    2001-04-01

    The Bajo Segura Basin is located in the eastern Betic Cordillera, at present connected with the Mediterranean Sea to the east. It has a complete stratigraphic record from the Tortonian to the Quaternary, which has been separated into six units bounded by unconformities. This paper is concerned with the northern edge of the basin, controlled by a major strike-slip fault (the Crevillente Fault Zone, CFZ), where the most complete stratigraphic successions are found. The results obtained (summarised below) are based on an integrated analysis of the sedimentary evolution and the subsidence-uplift movements. Unit I (Early Tortonian) is transgressive on the basin basement and is represented by ramp-type platform facies, organised in a shallowing-upward sequence related to tectonic uplift during the first stages of movement along the CFZ. Unit II (lower Late Tortonian) consists of shallow platform facies at bottom and pelagic basin facies at top, forming a deepening-upward sequence associated with tectonic subsidence due to sinistral motion along the CFZ. Unit III (middle Late Tortonian) is made up of exotic turbiditic facies related to a stage of uplift and erosion of the southern edge of the basin. Unit IV (upper Late Tortonian) consists of pelagic basin facies at bottom and shallow platform facies at top, defining a shallowing-upward sequence related to tectonic uplift during continued sinistral movement on the basin-bounding fault. Units V (latest Tortonian-Messinian) and VI (Pliocene-Pleistocene p.p.) consist of shallowing-upward sequences deposited during folding and uplift of the northern margin of the basin. No definitive evidence of any major eustatic sea-level fall, associated with the 'Messinian salinity crisis', has been recorded in the stratigraphic sections studied.

  10. Paleomagnetism of the Velez Rubio Dykes: Implications for transport directions in a collapsing orogen (Betic Cordillera, southern Spain)

    NASA Astrophysics Data System (ADS)

    Platzman, E. S.; Platt, J. P.

    2003-04-01

    Palaeomagnetic and structural analysis of a suite of altered Neogene mafic dykes intruded into the Alpujarride allochthon in the Internal Zone of the Betic Cordillera demonstrate that between 32-62° clockwise vertical-axis rotation occurred after the major extensional event on the adjacent Malaguide Alpujarride. Anisotropy of magnetic susceptibility (AMS) measurements show that the dykes are virtually free of a penetrative magnetic fabric associated with this deformational event. Results of demagnetization experiments show that the remanence in many of the dykes is composed of one to three components. The lowest temperature component is usually in the direction of the present earth's magnetic field and is interpreted as a viscous overprint. The intermediate temperature component is carried by pyrrhotite and frequently has a direction identical to the high temperature remanence fraction. The high temperature component, which demagnetizes at the curie point of magnetite (575 °C), has an average declination of 242° and an inclination of -19°. Lack of a well-defined magnetic fabric coupled with a shallow inclination suggests that these dykes have rotated about a horizontal as well as a vertical axis. Rotation of approximately 57° about a horizontal NNE-trending axis, normal to the dykes, brings the inclination into statistical agreement with the expected inclination for the Oligocene. This rotation leaves the dykes in a near-vertical orientation, decreases the declination anomaly to 32° and brings the foliation in the surrounding schists approximately horizontal. We suggest that the regional foliation may have been sub-horizontal at the time of dyke emplacement, probably as a result of the phase of late-orogenic extension. The regional stretching lineation and hence transport direction associated with the extensional event was originally oriented NNE. sub-parallel to the finite extension directions obtained further to the west implying a large component of radial

  11. Upper Pleistocene - Holocene activity of the Carrascoy Fault (Murcia, SE Spain): preliminary results from paleoseismological research.

    NASA Astrophysics Data System (ADS)

    Martin-Banda, Raquel; Garcia-Mayordomo, Julian; Insua-Arevalo, Juan M.; Salazar, Angel; Rodriguez-Escudero, Emilio; Alvarez-Gomez, Jose A.; Martinez-Diaz, Jose J.; Herrero, Maria J.; Medialdea, Alicia

    2014-05-01

    The Carrascoy Fault is located in the Internal Zones of the Betic Cordillera (Southern Spain). In particular, the Carrascoy Fault is one of the major faults forming the Eastern Betic Shear Zone, the main structure accommodating the convergence between Nubian and Eurasian plates in the westernmost Mediterranean. So far, the Carrascoy Fault has been defined as a left-lateral strike-slip fault. It extends for at least 31 km in a NE-SW trend from the village of Zeneta (Murcia) at its northeastern tip, to the Cañaricos village, controlling the northern edge of the Carrascoy Range and its linkage to the Guadalentin Depression towards the southwest. This is an area of moderate seismic activity, but densely populated, the capital of the region, Murcia, being settled very close to the fault. Hence, the knowledge of the structure and kinematics of the Carrascoy Fault is essential for assessing reliably the seismic hazard of the region. We present a detailed-scale geological and geomorphological map along the fault zone created from a LIDAR DEM combined with fieldwork, and geological and geophysical information. Furthermore, a number of trenches have been dug across the fault at different locations providing insights in the fault most recent activity as well as paleoseismic data. Preliminary results suggest that the Cararscoy Fault has recently changed its kinematic showing a near pure reverse motion. According to this, the fault can be divided into two distinct segments, the eastern one: Zeneta - Fuensanta, and the western one: Fuensanta - Cañaricos, each one having its own characteristic style and geodynamics. Some new active strands of the fault locate at the foot of the very first relief towards the North of the older strand, forming the current southern border of the Guadalentin Depression. These new faults show an increasingly reverse component westwards, so that the Fuensanta - Cañaricos segment is constituted by thrusts, which are blind at its western end

  12. Diagenetic evolution of Tortonian temperate carbonates close to evaporites in the Granada Basin (SE Spain)

    NASA Astrophysics Data System (ADS)

    López-Quirós, A.; Barbier, M.; Martín, J. M.; Puga-Bernabéu, Á.; Guichet, X.

    2016-04-01

    The Granada Basin (SE Spain) is a small basin located in the central part of the Betic Cordillera, structured as such in the late Tortonian and initially connected to the Atlantic Ocean and to the Mediterranean Sea. During the late Tortonian, normal marine conditions prevailed, leading to the deposition of skeletal carbonate sediments on platforms around structural highs. The marine connections were later interrupted, first to the Atlantic Ocean and then to the Mediterranean Sea, and a thick evaporite sequence, marking the transition from marine to continental conditions, was deposited during the latest Tortonian. In this work, the diagenetic evolution of the Tortonian temperate carbonates (TTC), underlying and close to the evaporite bodies, is revealed and discussed. The diagenetic study includes petrographic analyses (conventional petrography, cathodoluminescence, and fluorescence), geochemical analyses (major, minor and trace elements, and δ13C and δ18O stable isotopes), and microthermometry of fluid inclusions. In the TTC, marine diagenetic processes such as micritization and fibrous calcite-cement precipitation and mechanical compaction took place during or just after deposition (Eogenesis). An initial burial event (Mesogenesis 1) is characterized by: 1) stabilization of the temperate-water carbonates by freshwater, and 2) porosity occlusion via precipitation of low-Mg bladed and syntaxial/mosaic calcite cements. The TTC were then subaerially exposed (or got close to the surface) during evaporite deposition and underwent pedogenesis, Mg-smectite infiltration, and pyrite formation (Telogenesis 1). Subsequent brine-related diagenetic alterations, such as dolomitization and silica, halite, and sylvite replacements of carbonate grains occurred during a second burial episode (Mesogenesis 2) concomitant with the Messinian lacustrine deposition, this being followed by chemical compaction (stylolite formation). Finally, the area was uplifted and the TTC exhumed

  13. "High resolution seismic imaging of an active fault in the eastern Guadalquivir Basin (Betic Cordillera, Southern Spain)"

    NASA Astrophysics Data System (ADS)

    Serrano, Inmaculada; Torcal, Federico; Martín, José Benito

    2015-10-01

    We calculated the high resolution seismic velocity, Poisson's ratio, crack density and saturation ratio structures in and around the source areas of the Torreperogil seismic series (October 2012-April 2013). This seismic series, characterized by a large number of low magnitude (below Mw 3.7 or Md 3.9) and very shallow microearthquakes, took place in the Guadalquivir Basin, a large flexural foreland basin with a linear ENE-WSW trending bounded to the north by the Iberian Massif and to the south by the Betic Cordillera and filled from a middle Miocene to Plio-Quaternary sedimentary sequence. In the upper layers of the crust, strong low-velocity anomalies are extensively distributed under the central zone, which together with high Poisson's ratio and crack density values may correspond to rocks which are less likely to fracture, perhaps due to the accumulation of tectonic and seismic stress. 93% of the earthquakes occurred at depths of up to 8 km, which could indicate that the base of the seismogenic zone lies at this depth. The seismic series was concentrated in layers of strong structural heterogeneities (in the boundary area between low and high anomalies), which were likely to generate earthquakes due to differential strain accumulation beneath the region. The high velocity areas are also considered to be strong yet brittle parts of the fault zone, which may generate earthquakes (at depths of between 5 km and 9 km). By contrast, low velocity areas are less prone to fracture, allowing seismic slippage to take place (from 2 to 4 km depth). The best estimate of the depth of the main shock (mbLg 3.9) is 7.6 km, which could tend to nucleate at the base of the seismogenic zone, at the "fault end" on the boundary between a low velocity zone to the east and a high velocity zone to the west, indicating the fault plane which separates both areas laterally. Assuming that this seismic contrast is one of the main Torreperogil faults it could imply that stress has accumulated

  14. Geomorphological impacts of an extreme flood in SE Spain

    NASA Astrophysics Data System (ADS)

    Hooke, J. M.

    2016-06-01

    Long-term field studies in semiarid ephemeral streams are rare. These geomorphic data are essential for understanding the nature of the processes in order to develop modelling for risk assessments and management. An extreme flood event on 28 September 2012 affected the Murcia region of SE Spain, including long-tem monitoring sites on two fluvial systems in the Guadalentín basin, the Nogalte and Torrealvilla. Detailed morphological data were collected before and immediately after the event; and the amount of morphological change, erosion, and deposition have been related to peak flow conditions at the sites. On the Nogalte channel, peak flow reached 2500 m3 s- 1 at the downstream end of the catchment in less than 1 h. The event had a recurrence interval of > 50 years based on rainfall records and damage to old irrigation structures. The major effect in the braided, gravel channel of the Nogalte was net aggradation, with massive deposition in large flat bars. The measured changes in bankfull capacity were highly correlated with most hydraulic variables. Net changes in cut-and-fill in cross sections on the Nogalte were highly related to peak discharge and stream power but much less so to measures of hydraulic force (velocity, shear stress, unit stream power). Relationships of amount of erosion to hydraulic variables were much weaker than for amount of deposition, which was largely scaled to channel size and flow energy. Changes on the Torrealvilla were much less than on the Nogalte, and net erosion occurred at all sites. Sites on the Nogalte channel in schist exhibited higher deposition than those of the Torrealvilla sites on marl for the same hydraulic values. Overall, less morphological change took place in the extreme event on the Nogalte than predicted from some published hydraulic relations, probably reflecting the high sediment supply and the hydrological characteristics of the event. The results demonstrate the high degree of adjustment of these channels to

  15. Palaeoenvironmental implications of ferruginous deposits related to a Middle Upper Jurassic discontinuity (Prebetic Zone, Betic Cordillera, Southern Spain)

    NASA Astrophysics Data System (ADS)

    Reolid, Matías; Abad, Isabel; Martín-García, Juan Manuel

    2008-01-01

    The Middle-Upper Jurassic boundary in the westernmost Tethyan basins is marked by a discontinuity. A thin iron crust with ferruginous ooids and pisoids and an overlying ferruginous oolitic limestone lithofacies occur in a genetic relationship to this discontinuity with a reduced thickness (< 50 cm) and very local distribution in the Prebetic Zone (Betic Cordillera). The ferruginous coated grains are subdivided into two types. Type A ooids are characterised by thin, regular lamination in concentric layers enclosing a nucleus; they are dominant in the top of the iron crust (100% of the ferruginous ooids) and in the ferruginous oolitic limestone (82%). Type B ooids typically have thick, irregular lamination in a few discontinuous concentric layers enclosing a variable nucleus including bioclasts and foraminifera; they are exclusive to the ferruginous oolitic limestone (18% of the ferruginous ooids). The bulk chemical composition varies between 80% Fe 2O 3 by weight in the iron crust and 67% by weight in the coated grains. In the ferruginous ooids, the contents in SiO 2 (5.4%), Al 2O 3 (6.5%), P 2O 5 (3.6%), and CaO (4.7%) are higher than in the crust. Trace elements (V, Cr, Co, Ni, Zn, Y, Mo, and Pb) in both the crust and ooids show enriched values compared with the bulk composition of the upper continental crust. The mineral composition of the iron crust and ooids is primarily goethite, with small amounts of Al-hydroxide (bohemite) and apatite, whereas hematite is identified only in the iron crust. The Type A ooids are interpreted as having an origin related to the iron crust. Since there is no evidence to support a marine genesis for the iron crust, the possibility of a subaerial origin is presented here. The crust has characteristics (chemical and mineralogical composition) similar to those of ferruginous pisolitic plinthite (highly weathered redoximorphic soil), and goethite shows an Al-substitution range (5-10 mol%) that indicates pedogenic conditions. Soil

  16. The composition of nanogranitoids in migmatites overlying the Ronda peridotites (Betic Cordillera, S Spain): the anatectic history of a polymetamorphic basement

    NASA Astrophysics Data System (ADS)

    Acosta-Vigil, Antonio; Barich, Amel; Omar, Bartoli; Garrido, Carlos J.; Cesare, Bernardo; Remusat, Laurent; Poli, Stefano; Raepsaet, Caroline

    2016-04-01

    The study of the composition of primary melts during anatexis of high-pressure granulitic migmatites is relevant to understand the generation and differentiation of continental crust. Peritectic minerals in migmatites can trap dropless of melt that forms via incongruent melting reactions during crustal anatexis. These melt inclusions commonly crystallize and form nanogranitoids upon slow cooling of the anatectic terrane. To obtain the primary compositions of crustal melts recorded in these nanogranitoids, including volatile concentrations and information on fluid regimes, they must be remelted and rehomogenize before analysis. A new occurrence of nanogranitoids was recently reported in garnets of mylonitic metapelitic gneisses (former high pressure granulitic migmatites) at the bottom of the prograde metamorphic sequence of Jubrique, located on top of the Ronda peridotite slab (Betic Cordillera, S Spain). Nanogranitoids within separated chips of cores and rims of large garnets from these migmatites were remelted at 15 kbar and 850, 825 or 800 °C and dry (without added H2O), during 24 hours, using a piston cylinder apparatus. Although all experiments show glass (former melt) within melt inclusions, the extent of rehomogenization depends on the experimental temperature. Experiments at 850-825 °C show abundant disequilibrium microstructures, whereas those at 800 °C show a relatively high proportion of rehomogenized nanogranitoids, indicating that anatexis and entrapment of melt inclusions in these rocks was likely close to 800 °C. Electron microprobe and NanoSIMS analyses show that experimental glasses are leucogranitoid and peraluminous, though define two distinct compositional groups. Type I corresponds to K-rich, Ca- and H2O-poor leucogranitic melts, whereas type II represents K-poor, Ca- and H2O-rich granodioritic to tonalitic melts. Type I and II melt inclusions are found in most cases at the cores and rims of large garnets, respectively. We tentatively

  17. The Messinian early Pliocene stratigraphic record in the southern Bajo Segura Basin (Betic Cordillera, Spain): Implications for the Mediterranean salinity crisis

    NASA Astrophysics Data System (ADS)

    Soria, Jesús M.; Caracuel, Jesús E.; Corbí, Hugo; Dinarès-Turell, Jaume; Lancis, Carlos; Tent-Manclús, José E.; Viseras, César; Yébenes, Alfonso

    2008-01-01

    The analysis of the Messinian and Pliocene stratigraphy of the southern Bajo Segura Basin (Betic Cordillera, Spain) has revealed three highstand sedimentary phases (Messinian I, Messinian II, and Pliocene) bounded by two lowstand erosional surfaces (intra-Messinian and end-Messinian unconformities). The Messinian I highstand phase is characterized by the progradation of coastal and shallow marine sandstones (La Virgen Fm) over slope and pelagic-basin marls (Torremendo Fm). After this first phase, a fall in sea level brought about the intra-Messinian unconformity, a subaerial erosional surface with local accumulations of karstic breccias and caliche-like carbonate crusts. The Messinian II highstand phase is represented by sandy beaches and muddy lagoons (Garruchal Fm) correlative with shallow marine evaporites (San Miguel Fm); this second phase records the intra-Messinian reflooding of the basin, which characterizes the salinity crisis in the marginal basins of the Mediterranean. A new sea-level fall resulted in the end-Messinian unconformity, of which the most significant feature is the presence of a broad palaeovalley, c. 200 m deep, which, along its course, completely eroded the deposits of the Messinian II phase and part of the deposits of the Messinian I phase. The Pliocene highstand phase begins with coastal and shallow marine conglomerates and sandstones (La Pedrera Fm) which fill the deep part of the above-mentioned palaeovalley. These bottom deposits evolved gradually upwards towards pelagic marls (Hurchillo Fm), over which shallow marine and coastal sandstones prograded (Rojales Fm). This third phase records the flooding of the basin at the beginning of the Pliocene, when the salinity crisis ended in the marginal basins of the Mediterranean. The combination of calcareous nannoplankton biostratigraphy and magnetostratigraphy has confirmed that both the end of the sedimentation of the Messinian I phase, as well as the two lowstand erosional surfaces (intra

  18. Using nanogranitoids and phase equilibria modeling to unravel anatexis in the crustal footwall of the Ronda peridotites (Betic Cordillera, S Spain)

    NASA Astrophysics Data System (ADS)

    Bartoli, Omar; Acosta-Vigil, Antonio; Tajčmanová, Lucie; Cesare, Bernardo; Bodnar, Robert J.

    2016-07-01

    Anatexis in the crustal footwall of Ronda peridotites (Betic Cordillera, S Spain) is apparently related to the hot emplacement of this mantle slab over metasedimentary rocks. In this study, we combine the analysis of melt inclusions (MI) and phase equilibria calculations on quartzo-feldspathic mylonites (former migmatites) occurring at the contact with the mantle rocks, in the region of Sierra Alpujata (Ojén unit). The goal is to better characterize anatexis in these rocks and to provide new constraints on the geodynamic evolution of the crustal footwall. Such data are important for understanding the mechanisms of crustal emplacement of the mantle slice. The quartzo-feldspathic mylonites are characterized by the mineral assemblage Qtz + Pl + Kfs + Sil + Grt + Ilm + Bt ± Ap ± Gr. Clusters of MI are observed both at the core and toward the rim of peritectic garnet. In each cluster, MI range from totally glassy to nanogranitoids, consisting of Qtz + Kfs + Bt + Ms + Pl aggregates. The trapped melt is leucogranitic and peraluminous with variable Na2O/K2O values and low H2O contents (≈ 2-4 wt%). Phase equilibria modeling in the MnO-Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2-TiO2-O2-C (MnNCaKFMASHTOC) system with graphite-saturated fluid constrains the P-T conditions of melting at ≈ 6 kbar, ≈ 820 °C. MI data support the fluid-absent character of melting. The investigated MI represent the primary anatectic melts produced during prograde anatexis of the host rocks via biotite dehydration melting. Field, compositional, and textural observations indicate that mylonitic migmatites represent strongly deformed former diatexites. The comparison between the new data and some recently published information on migmatites located further from the contact with the peridotites and toward the bottom of the crustal footwall, raises some important issues which question the previously proposed geodynamic models for this region. Among them, (i) the crustal footwall at Sierra Alpujata

  19. Lower Bashkirian conodonts from the Nevado-Filábride complex (Betic Cordilleras, Spain): tectonic and palaeogeographic implications

    NASA Astrophysics Data System (ADS)

    Rodríguez Cañero, Rosario; Jabaloy Sánchez, Antonio; Navas Parejo, Pilar; Martín Algarra, Agustín

    2017-04-01

    The Nevado-Filábride Complex is a fragment of the Variscan-Alleghanian belt that was recycled during the Alpine Orogeny. This makes difficult the interpretation of its pre-Mesozoic tectonic provenance and of general palaeogeographic meaning. However, it is a key terrain to understand the geometry and the evolution of the Betic Orogen. Here, we report for the first time the presence of lower Bashkirian conodonts (Declinognathodus bernesgae, D. inaequalis, D. praenoduliferous and Idioprioniodus sp. elements) in black limestones at the base of the Aulago Fm in the lowest tectonic unit of the Nevado-Filábride Complex (Bodurria Unit). The samples come from graphite-rich thin fine detrital marble horizons between fine-grained low-grade slates with some rippled quartzite horizons. These metasediments were deposited in moderately deep and calm anoxic marine environments, only sporadically affected by bottom currents. This finding supports a correlation of the Nevado-Filábride terrains to the Cantabrian and the West Asturian Leonese tectono-palaeogeographic realms of the Variscan Iberian Massif. This correlation indicates that, below the Betic deformational front, the Iberian palaeogeographic realms continued towards the SE to connect with the continental margin related to the westernmost Palaeotethys.

  20. Curved fold-and-thrust accretion during the extrusion of a synorogenic viscous allochthonous sheet: The Estepa Range (External Zones, Western Betic Cordillera, Spain)

    NASA Astrophysics Data System (ADS)

    Pedrera, Antonio; MaríN-Lechado, Carlos; Martos-Rosillo, Sergio; RoldáN, Francisco Javier

    2012-08-01

    New structural, borehole, and time domain electromagnetic data allow us to reconstruct the 3-D geometry of the Estepa range (External Zones of the Western Betic Cordillera), which constitutes an isolated curved fold-and-thrust range made up of Jurassic shallow marine carbonates and Cretaceous to Paleocene marls and marly limestones. Contraction and rising load linked to the accretion of the Subbetic nappe enhanced the expulsion of Triassic evaporites and overpressured clays during the early and middle Miocene, finally forming part of a highly deformed mélange unit. This plastic extrusion favored the disconnection of External and Middle Subbetic blocks, including the Sierra de Estepa Range. There, deformation is characterized by northwest-vergent curved folds-and-thrusts associated with NE-SW frontal ramps and NW-SE lateral transfer faults that segmented the folds active between 18 and 12 Ma. At a local scale, curvature was achieved under a nearly uniform NW/WNW transport direction suggesting a primary arc type. Friction variation across the heterogeneous detached plastic basal Triassic unit mainly controlled the curvature and segmentation of the fold systems. Transport direction is consistent with previously published slip data from the Internal Subbetic and the Campo de Gibraltar units. After the Late Serravallian, accretion slowed down and a shallow marine unit deposited unconformably placed over the main thrust and folds. The sequence of deformation and emplacement of these ranges is interpreted as a continuous process linked to the early Miocene E continental collision of the Iberian margin thin continental crust and subduction of the Flysch trough oceanic crust beneath the Alboran continental domain.

  1. Architecture and tectono-stratigraphic evolution of the intramontane Baza Basin (Bétics, SE-Spain): Constraints from seismic imaging

    NASA Astrophysics Data System (ADS)

    Haberland, Christian; Gibert, Luis; Jurado, María José; Stiller, Manfred; Baumann-Wilke, Maria; Scott, Gary; Mertz, Dieter F.

    2017-07-01

    The Baza basin is a large Neogene intramontane basin in the Bétic Cordillera of southern Spain that formed during the Tortonian (late Miocene). The Bétic Cordillera was produced by NW-SE oblique convergence between the Eurasian and African Plates. Three seismic reflection lines (each 18 km long; vibroseis method) were acquired across the Baza basin to reveal the architecture of the sedimentary infill and faulting during basin formation. We applied rather conventional CDP data processing followed by first arrival P-wave tomography to provide complementary structural information and establish velocity models for the post-stack migration. These images show a highly asymmetric structure for the Basin with sediments thickening westward, reaching a maximum observed thickness of > 2200 m near the governing Baza Fault zone (BFZ). Three major seismic units (including several subunits) on top of the acoustic basement could be identified. We use stratigraphic information from the uplifted block of the BFZ and other outcrops at the basin edges together with available information from neighboring Bétic basins to tentatively correlate the seismic units to the known stratigraphy in the area. Until new drilling or surface outcrop data is not available, this interpretation is preliminary. The seismic units could be associated to Tortonian marine deposits, and latest Miocene to Pleistocene continental fluvio-lacustrine sediments. Individual strands of the BFZ truncate the basin sediments. Strong fault reflections imaged in two lines are the product of the large impedance contrast between sedimentary fill and basement. In the central part of the Basin several basement faults document strong deformation related to the early stages of basin formation. Some of these faults can be traced up to the shallowest imaged depth levels indicating activity until recent times.

  2. The Dúdar landslide: a huge slope instability associated to active tectonics in the NE border of the Granada Basin (SE Spain)

    NASA Astrophysics Data System (ADS)

    Rodríguez-Peces, M. J.; Pérez-Peña, J. V.; Azañón, J. M.; Ureña, C.

    2012-04-01

    The Dúdar landslide is located at the eastern border of the Granada Basin (South Spain), which is a Neogene-Quaternary intramontane depression located in the central part of the Betic Cordillera. The mean landslide area is about 380 ha and can be regarded as one of the largest landslides developed in this part of the cordillera. The landslide development was controlled by the great altitude differences between the Aguas Blancas and Darro rivers, which in turn are the consequence of the tectonic activity of the NW-SE striking normal faults of the northeast border of the Granada Basin and the related NE-SW directed-folds. This tectonic activity produces uplift of the footwall block developing unstable slopes. In the northwest margin of the Aguas Blancas River, slope instabilities are also determined by the relative bad geotechnical quality of the materials involved, which are mainly marls and silty sediments with gypsum interlayers. As for other large landslides located in the Granada Basin (e.g. Güevéjar landslide), the most likely triggering factor seems to be a great earthquake. Nevertheless, there are not historical data for such event but probably occurred prior to 1400, which is the date of the first historical records of the Dúdar village, located in one side of the landslide. In addition, the active faults in the NE border of the Granada Basin can potentially generate earthquakes with magnitudes greater than Mw=6.0, making the Granada Basin one of the most seismically active regions of Spain. In this work, we have carried out a geomorphologic description of the Dúdar landslide with the aid of a high-resolution digital elevation model (DEM) derived from LIDAR data. We have analysed the significant changes that the landslide caused in the drainage system of the Aguas Blancas and Darro rivers. These modifications comprise river diversions and active incision within the body of the landslide, making it susceptible to future reactivations. Finally, a

  3. Internal structure of a collapsed terrain. The Lújar syncline and its significance for the fold- and sheet-structure of the Alborán Domain (Betic Cordilleras, Spain)

    NASA Astrophysics Data System (ADS)

    Orozco, Miguel; Álvarez-Valero, Antonio M.; Alonso-Chaves, Francisco M.; Platt, John P.

    2004-07-01

    Detailed structural analysis of the Sierra de Lújar in the western Alpujarras region (Betic Cordilleras, S Spain), a very representative area of the terrain known as the Alborán Domain, has revealed the existence of a very large N-vergent recumbent syncline which involves the whole mountain massif and neighbouring areas. The Lújar syncline and, probably, the associated recumbent anticline which crops out southeast of Sierra de Lújar show a great variation in the orientation of the hinge line. Although having a curved shape, the hinge line is contained in a plane whose attitude coincides with the main attitude of the axial-plane crenulation foliation (Sc), suggesting that it is a sheath fold. The strongly deformed overturned limb of the syncline is cut by two low-angle normal faults displacing towards the north. Similarity in the kinematics between the faults and the fold, and the association between the faults and the high-strain zone in the overturned limb of the fold, suggest that they are related. Regional constraints on the age of the crenulation cleavage and the low-angle normal faults indicate that they formed during the early Miocene late-orogenic extensional event in the Alborán Domain. We propose an alternate explanation for the structure of the Alpujarras region in which the Lújar syncline forms part of a recumbent syncline-anticline pair that extends along much of the Alpujarride outcrop in the southern Betic Cordillera. In several places, the fold is disrupted by low-angle normal faults, and it is overlain by an upper Alpujárride extensional sheet mainly composed of medium- to high-grade metamorphic rocks. We suggest that all these structures arose from the extensional deformation under decreasing temperature conditions of a previously thickened and metamorphosed orogenic crust.

  4. Levelling Profiles and a GPS Network to Monitor the Active Folding and Faulting Deformation in the Campo de Dalias (Betic Cordillera, Southeastern Spain)

    PubMed Central

    Marín-Lechado, Carlos; Galindo-Zaldívar, Jesús; Gil, Antonio José; Borque, María Jesús; de Lacy, María Clara; Pedrera, Antonio; López-Garrido, Angel Carlos; Alfaro, Pedro; García-Tortosa, Francisco; Ramos, Maria Isabel; Rodríguez-Caderot, Gracia; Rodríguez-Fernández, José; Ruiz-Constán, Ana; de Galdeano-Equiza, Carlos Sanz

    2010-01-01

    The Campo de Dalias is an area with relevant seismicity associated to the active tectonic deformations of the southern boundary of the Betic Cordillera. A non-permanent GPS network was installed to monitor, for the first time, the fault- and fold-related activity. In addition, two high precision levelling profiles were measured twice over a one-year period across the Balanegra Fault, one of the most active faults recognized in the area. The absence of significant movement of the main fault surface suggests seismogenic behaviour. The possible recurrence interval may be between 100 and 300 y. The repetitive GPS and high precision levelling monitoring of the fault surface during a long time period may help us to determine future fault behaviour with regard to the existence (or not) of a creep component, the accumulation of elastic deformation before faulting, and implications of the fold-fault relationship. PMID:22319309

  5. The effects of lateral density gradients, slopes and buoyancy on channel flow: 1D analytical solutions and applications to the SE Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Gervais, Félix; Ranalli, Giorgio

    2017-08-01

    We present 1D analytical solutions for channel flow in orogens driven by various types of pressure gradients. Our calculations demonstrate that lateral density gradients in the upper crust, such as would occur across a suture zone separating arc rocks from pericratonic sediments provide a driving force for Poiseuille flow as large as topographic gradients observed in modern mountain belts. For cases for which the gradients are external (topographic and lateral density gradients) and internal (e.g. partial melting of channel material) to the channel, inclination decreases and increases the Poiseuille component of the average flow-velocity within the channel by the cosine and sine of the slope, respectively. The magnitude of the pressure gradient consequent upon the buoyancy generated by partial melting of metapelites in a channel with a 30° slope, such as would occur above an underthrusting basement ramp, is similar to that of topographic or lateral density gradients. Channel flow up a ramp could thus constitute an important exhumation mechanism in large hot orogens. Our calculations indicate that mid-crustal channel flow was a highly likely process in the Late Cretaceous-Paleocene setting of the southeastern Canadian Cordillera. The flow was first driven by the lateral density contrast between pericratonic sediments and the arc-related Intermontane terrane, then by combined effect of topographic gradient and melt-induced buoyancy of the Lower Selkirk Allochthon (part of the Shuswap Complex). Flow up the underthrusting basement ramp resulted in exhumation from mid- to upper-crustal levels. Channel flow then migrated downward to involve basement and overlying cover sequence rocks. Our results indicate that syn-convergent channel flow was a viable and very likely process in the southeastern Canadian Cordillera.

  6. Evidence of a large deep conductive body within the basement of the Guadalquivir foreland Basin (Betic Cordillera, S-Spain) from tipper vector modelling: Tectonic implications

    NASA Astrophysics Data System (ADS)

    González-Castillo, L.; Galindo-Zaldívar, J.; Junge, A.; Martínez-Moreno, F. J.; Löwer, A.; Sanz de Galdeano, C.; Pedrera, A.; López-Garrido, A. C.; Ruiz-Constán, A.; Ruano, P.; Martínez-Martos, M.

    2015-11-01

    The Betic Cordillera is an Alpine belt formed by the interaction of the Eurasian and African plates and the westward motion of the Alboran Domain. Long Period Magnetotelluric observations at 26 sites in its westernmost part provide induction arrows that have been compared with 3D forward models including bathymetry and major geological bodies. The results highlight the presence of a major conductive body (0.05 Ω m) unknown to date and located within the basement of the Guadalquivir foreland basin. Aeromagnetic and field magnetic measurements further support the occurrence of magnetic anomalies related to the top of this anomalous body. This major structure is interpreted as an intermediate or basic igneous rock, with a high proportion of metallic mineralization. Its origin is discussed in the framework of the regional geological setting, possibly produced in the southern Iberian Variscan Massif by a huge concentration of volcanogenic massive sulphide (VMS) in the prolongation of the Iberian Pyrite Belt during Devonian-early Carboniferous times. Another possibility is that the conductive anomaly is due to magmatic intrusions associated with the Mesozoic fragmentation of Southern Iberia and the opening of the Tethys.

  7. Record of epicontinental platform evolution and volcanic activity during a major rifting phase: The Late Triassic Zamoranos Formation (Betic Cordillera, S Spain)

    NASA Astrophysics Data System (ADS)

    Pérez-López, Alberto; Pérez-Valera, Fernando; Götz, Annette E.

    2012-03-01

    The study of the Late Triassic Zamoranos Formation and the comparison to coeval carbonate units provides new insights into the evolution and palaeogeography of carbonate platforms during major rifting phases in the Earth's history. The platform carbonates of the Zamoranos Formation record the last major transgression during the Triassic, and document the initial phase of the CAMP volcanism in the external Zone of the Betic Cordillera. New palynological data from the lower part of the Zamoranos Formation indicate a Middle Norian age. The entire succession is built up by limestones, dolomites, and ferruginous red detrital deposits with volcaniclastic breccias. The carbonates are interpreted as tidal and shallow marine sediments, deposited under arid conditions. The red detrital deposits appear in coastal environments in relation to a volcanic event, which triggered hydrothermal processes in these deposits and started the massive magmatic event associated with the Central Atlantic Magmatic Province (CAMP). The Zamoranos Formation was also recognized in the SW part of the Valencia Triassic and is correlated to the Imón Formation (Iberian Ranges), to the Isábena Formation (Pyrenees) and to other carbonate units of the W Tethys realm (Aquitaine, Tunisian Atlas, West Carpathians). These units indicate that an extensive epicontinental platform developed during the Late Triassic.

  8. New fossil teeth of Theropithecus oswaldi (Cercopithecoidea) from the Early Pleistocene at Cueva Victoria (SE Spain).

    PubMed

    Ferràndez-Cañadell, Carles; Ribot, Francesc; Gibert, Lluís

    2014-09-01

    The presence of Theropithecus oswaldi in Europe was first reported in 1995 from the Early Pleistocene site of Cueva Victoria (SE Spain), showing the dispersal of this genus above 30° north latitude and into Europe. Later claims of the presence in Italy of Theropithecus in the Early Pleistocene, based on vertebral remains, are controversial. Here we report four additional teeth of T. oswaldi from Cueva Victoria. These and the previously described tooth correspond to a minimum of two individuals. The presence of T. oswaldi in North Africa and SE Iberia during the Early Pleistocene suggests a possible faunal dispersal from Africa into Europe through the Straits of Gibraltar, which would have acted as a filter bridge.

  9. Lithofacies, diagenetic spectra and sedimentary cycles of messinian (Late Miocene) evaporites in SE Spain

    NASA Astrophysics Data System (ADS)

    Michalzik, Dieter

    1996-11-01

    Messinian evaporites have been deposited within a number of connected basins that formed the so-called 'Betic Strait' in SE Spain during the Late Miocene. Pre-, syn- and postevaporitic sedimentary successions may well be compared with other strata of the same age surrounding the Mediterranean Sea. There is no evidence for a cataract-like connection of these basins with a strong unidirectional flow regime before and during the formation of Messinian evaporites as previously suggested. The most frequently occurring gypsum lithofacies presumably related to shallow-water depositional environments are crystalline selenitic gypsum ('grass-like gypsum'), laminated gypsum and cross-bedded gypsarenite. Only few real sabkha type chicken wire alabastrine gypsum have been identified. Evenly laminated gypsum together with graded gypsarenites (turbidites), gypsrudites (debrites) and slumps is restricted to basins or parts of basins with considerable paleoslopes. Evidence for diagenetic overprinting is abundant in all outcrop areas studied. This includes the formation of giant gypsum twin crystals, 'super cones' and alabastrine nodular gypsum. The formation of Messinian evaporites in SE Spain is thought to be controlled by a superimposed third-order sea-level lowstand. Smaller sedimentary units fall well into the range of fourth- to sixth-order cyclic and rhythmic successions. They are clearly related to basin dynamics or to autogenetic processes of the local facies zone (facies dynamics). None of the smaller-scale cycles (fourth and higher order), as observed in outcrops, are related to high-frequency eustasy.

  10. The differentiation of units in the Nevado-Filábride complex (Betic Cordillera, Spain). A revision based on a geochronological study of detrital zircons

    NASA Astrophysics Data System (ADS)

    Santamaría-López, Ángel; Ruiz-Cruz, María Dolores; Sanz de Galdeano, Carlos

    2017-04-01

    The Nevado-Filábride complex is the lower metamorphic complex of the Betic Internal Zone (SE Spain). Its subdivision and age have been discussed over the years. It has been proposed the existence of various units, including one of the most accepted subdivision which aims to existence of two tectonics units (or nappes according the terminology of some authors): the lowermost Veleta unit (mainly formed by graphite schists and quartzites) and the upper Mulhacén unit (formed by micaschists, quartzites, metabasites, gneisses and marbles). However, in our opinion, the existence of those units is not supported by field data. Conversely, the lithological similarities present between the lower and upper part of the stratigraphic succession and the absence of notorious tectonic contacts point to existence of a continuous succession in the complex. In this work we present U/Pb age preliminary determinations of detrital zircons acquired from different samples corresponding to rocks that are assigned to the Veleta and Mulhacén units. The aim of the work is the determination of the younger zircon age included in the meta-sediments in order to obtain the maximum ages of sedimentation, but also to find similarities or differences of the zircon age populations between the Veleta and the Mulhacén units. The results obtained are: 1) 272.6 ± 1.8 Ma is the youngest zircon age. The sample was taken in the upper part of the Mulhacén unit in the western area of Sierra Nevada. The obtained age points to a middle Permian for the maximum age of sedimentation. This age is in line with the U/Pb ages obtained by various authors from gneisses taken from equivalent parts of the complex, which show approximately Permian to upper Carboniferous ages. 2) Samples taken from the lower part of the petrological succession show upper Carboniferous as younger ages. 3) Although samples were taken from different stratigraphic positions of the Veleta and Mulhacén units, we have observed the existence

  11. Late Neogene-Recent uplift of the Cabo de Gata volcanic province, Almerı´a, SE Spain

    NASA Astrophysics Data System (ADS)

    Martín, José M.; Braga, Juan C.; Betzler, Christian

    2003-02-01

    Cabo de Gata is a Miocene volcanic province in the Betic Cordillera in southeastern Spain. The distribution of coastal deposits in the successive marine sedimentary units overlying the last volcanic episode (about 7.5 Ma old) has been used to reconstruct the post-volcanic palaeogeographic evolution of the region during the Late Neogene. The current elevation of well-dated shoreline marker rocks has been used to estimate uplift amount and rates. Since the late Tortonian, a N45°E-aligned (the strike of the Carboneras fault system) topographic relief was emergent in the Cabo de Gata region. The extension and height of this island increased throughout the late Neogene. Smaller, independent islands were emergent and finally became connected to the main island during the Messinian. The Carboneras and Agua Amarga Pliocene sub-basins were the last two marine basins prior to the final emergence of the region. Since the last volcanic eruption (ca. 7.5 Ma), maximum uplift of sedimentary rocks in Cabo de Gata has taken place on the western margin of the N45°E-aligned palaeorelief. The altitude of the shoreline marker rocks in the successive sedimentary units decreases eastwards to the present-day coast and northwards of the Rambla del Plomo. Uplift rates since deposition remain nearly constant for the successive Messinian rocks and decrease slightly for the lower Pliocene outcrops. Most of the uplift took place before the Pliocene while the main island enlarged. Uplift amounts and rates since deposition of the upper Neogene sedimentary units in the Cabo de Gata area are similar to the ones estimated for laterally equivalent units in the eastern Betic basins (approximately 50 m/Ma). Despite its volcanic nature and the occurrence of the Carboneras fault system, the Cabo de Gata probably became elevated as a consequence of regional uplift in connection with the rest of the Betic Cordillera.

  12. Spreading of pollutants from alkaline mine drainage. Rodalquilar mining district (SE Spain).

    PubMed

    González, V; García, I; del Moral, F; de Haro, S; Sánchez, J A; Simón, M

    2012-09-15

    In the Rodalquilar mining district of SE Spain, a total of 46 soil samples that were between 0 and 20 cm in depth were taken from the tailings dump, stream sediments, and surfaces that were presumably were unaffected by mining. In each soil sample, organic carbon content, pH, particle size distribution and total and soluble trace element content were analysed. Pollutants were scattered by runoff from two source areas: tailings from Au mining (Sn, Sb, As and Se) and wastes from Pb mining (Pb, Cu and Zn). Sn, Pb, and Sb were spread mostly in the solid phase of the runoff, while Cu, Zn, As and Se were spread in both the solid and soluble phases of the runoff. The pollutants with the highest soluble concentrations were As and Se, which were scattered at greater distances from the source. Some evidence suggests that tailings from Au mining could also be scattered by wind, but no farther than 1500 m from the source. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. [Aerobiological study of Alternaria and Cladosporium conidia in the atmosphere of Almeria (SE Spain)].

    PubMed

    Sabariego Ruiz, Silvia; Díaz de la Guardia Guerrero, Consuelo; Alba Sánchez, Francisca

    2004-09-01

    This study analysed the seasonal and intradiurnal behaviour of fungal spores from Alternaria and Cladosporium on air samples collected in the city of Almeria (SE Spain), as well as the influence that meteorological parameters have on the concentration of these type of spores. Aerobiological sampling was made during four years (1998-2001) using a Hirst-type volumetric spore trap. Spores of Alternaria and Cladosporium were detected throughout the year, reaching the highest concentrations from May to October. The diurnal patterns of these taxons reflected a presence similar of spores during a 24 h period, with values horary close to 4% of total sampling daily. The correlations show a positive association with temperature, hours of sunshine and accumulate rainfall, but negative with daily rainfall.

  14. 3D geometry of growth strata in a fault-propagation fold: insights into space-time evolution of the Crevillente Fault (Abanilla-Alicante sector), Betic Cordillera, Spain

    NASA Astrophysics Data System (ADS)

    Martin-Rojas, I.; Alfaro, P.; Estévez, A.

    2015-07-01

    This work presents a 3D geometric model of growth strata cropping out in a fault-propagation fold associated with the Crevillente Fault (Abanilla-Alicante sector) from the Bajo Segura Basin (eastern Betic Cordillera, southern Spain). The analysis of this 3D model enables us to unravel the along-strike and along-section variations of the growth strata, providing constraints to assess the fold development, and hence, the fault kinematic evolution in space and time. We postulate that the observed along-strike dip variations are related to lateral variation in fault displacement. Along-section variations of the progressive unconformity opening angles indicate greater fault slip in the upper Tortonian-Messinian time span; from the Messinian on, quantitative analysis of the unconformity indicate a constant or lower tectonic activity of the Crevillente Fault (Abanilla-Alicante sector); the minor abundance of striated pebbles in the Pliocene-Quaternary units could be interpreted as a decrease in the stress magnitude and consequently in the tectonic activity of the fault. At a regional scale, comparison of the growth successions cropping out in the northern and southern limits of the Bajo Segura Basin points to a southward migration of deformation in the basin. This means that the Bajo Segura Fault became active after the Crevillente Fault (Abanilla-Alicante sector), for which activity on the latter was probably decreasing according to our data. Consequently, we propose that the seismic hazard at the northern limit of the Bajo Segura Basin should be lower than at the southern limit.

  15. Origin and significance of spinel pyroxene symplectite in lherzolite xenoliths from Tallante, SE Spain

    NASA Astrophysics Data System (ADS)

    Shimizu, Yohei; Arai, Shoji; Morishita, Tomoaki; Ishida, Yoshito

    2008-09-01

    We found spinel pyroxene symplectites in lherzolite xenoliths from Tallante, SE Spain, and investigated their petrographical and geochemical signatures. The spinel pyroxene symplectites are divided into two types, a spinel-type (= opx + cpx + sp) and a plagioclase-type (= opx + cpx + sp + pl) symplectites. The symplectites are always surrounded by lenticular aggregates of coarser-grained spinel pyroxene. The petrography and major-element chemistry of bulk symplectites indicate an origin through subsolidus reaction between olivine and garnet like at Horoman (Japan; Morishita and Arai, Contrib Mineral Petrol 144:509 522, 2003). The spinel pyroxene symplectites at Tallante were of garnet origin. However, the bulk Tallante spinel pyroxene symplectites show a relatively flat rare earth element (REE) distribution with slight light REE (LREE) enrichment, i.e. there was no trace-element signature typical of mantle garnet. They also differ from the Horoman symplectites that occasionally preserve a garnet trace-element signature, i.e. depletion of LREE and enrichment of heavy REE. These conflicting results indicate that the symplectites record slight enrichment in pyroxene compositions during or after depletion by melt extraction and breakdown of garnet by decompression, and all the minerals including symplectite constituents have been homogenized in the stability field of spinel to plagioclase lherzolite, with the assistance of some melt (possibly an alkaline silicate melt; Downes, J Petrol 42:233 250, 2001). Moreover, some of the spinel-type symplectites experienced heating by injection of Si-rich melt, and consequently have been transformed to the plagioclase-type symplectite. The Tallante spinel pyroxene symplectites developed from garnet + olivine and were carried from the garnet lherzolite stability field to the spinel and to the plagioclase lherzolite stability fields. Our data indicates mantle upwelling (mantle diapirism) beneath the Betic Rif zone in southern Spain.

  16. Reconstruction of past climate variability in SE Spain between 14 and 8 ka

    NASA Astrophysics Data System (ADS)

    Budsky, Alexander; Scholz, Denis; Mertz-Kraus, Regina; Christoph, Spötl; Gibert, Luis; Jochum, Klaus Peter; Andreae, Meinrat O.

    2016-04-01

    In comparison to the large climatic oscillations during the Pleistocene, Holocene climate only underwent minor changes. Nevertheless, cyclic climate changes also occurred during the Holocene. The Bond events, represented by the presence of cold, ice-bearing waters from the north of Iceland as far south as the latitude of Britain, occurred at a cyclicity of about 1500 a and were particularly pronounced during the Early Holocene. However, their climatic impact on the terrestrial realm was not consistent over Europe, in particular with respect to changes in precipitation. Here we present a precisely dated high-resolution flowstone record from Cueva Victoria, SE Spain, a site well suited to study the competing influence of the Atlantic and Mediterranean Sea on the southern Iberian Peninsula. We sampled several flowstones with a thickness of up to 60 cm. 230Th/U-dating has shown that these deposits mainly formed during relatively warm climate intervals of the Middle and Late Pleistocene, i.e. interglacials and interstadials (Budsky et al., 2015; Gibert et al., 2016). Here we focus on a short (11 cm) flowstone sequence from the Holocene with a high temporal resolution (centennial for stable isotopes and annual for trace elements). The flowstone grew between 14 and ca. 8 ka b2k. The decreasing trend of the δ18O and δ13C values as well as of several trace elements between 12 and 11 ka b2k reflects an increase in temperature and precipitation at the beginning of the Holocene. In particular, Sr and Mg show a trend towards low and stable values. Subsequently, from 10.5 to 8 ka b2k, the δ13C values show a high variability (-11 to -4), whereas the δ18O values are rather stable (between -6 and -7). Maxima in δ13C are interpreted as drier conditions in response to Bond events. These events possibly led to a change of the atmospheric circulation, affecting the vegetation in SE Spain, which evolved towards an open C3 vegetation at ca. 8 ka b2k concomitant with drier conditions

  17. Hyperextension of continental lithospheric mantle to oceanic-like lithosphere: the record of late gabbros in the Ronda subcontinental lithospheric mantle section (Betic Cordillera, S-Spain)

    NASA Astrophysics Data System (ADS)

    Hidas, Karoly; Garrido, Carlos; Targuisti, Kamal; Padron-Navarta, Jose Alberto; Tommasi, Andrea; Marchesi, Claudio; Konc, Zoltan; Varas-Reus, Maria Isabel; Acosta Vigil, Antonio

    2014-05-01

    Rupturing continents is a primary player in plate tectonic cycle thus longevity, stability, evolution and breakup of subcontinental lithosphere belongs for a long time to a class of basic geological problems among processes that shape the view of our Earth. An emerging body of evidences - based on mainly geophysical and structural studies - demonstrates that the western Mediterranean and its back-arc basins, such as the Alborán Domain, are hyperextended to an oceanic-like lithosphere. Formation of gabbroic melts in the late ductile history of the Ronda Peridotite (S-Spain) - the largest (ca. 300 km2) outcrop of subcontinental lithospheric mantle massifs on Earth - also attests for the extreme thinning of the continental lithosphere that started in early Miocene times. In the Ronda Peridotite, discordant gabbroic veins and their host plagioclase lherzolite, as well as gabbroic patches in dunite were collected in the youngest plagioclase tectonite domains of the Ojén and Ronda massifs, respectively. In Ojén, gabbro occurs as 1-3 centimeter wide discordant veins and dikes that crosscut the plagioclase tectonite foliation at high angle (60°). Within the veins cm-scale igneous plagioclase and clinopyroxene grains show a shape preferred orientation and grow oriented, subparallel to the trace of high temperature host peridotite foliation and oblique to the trend of the vein. In contrast to Ojén, mafic melts in the Ronda massif crystallized along subcentimeter wide anastomozing veins and they often form segregated interstitial melt accumulations in the host dunite composed of plagioclase, clinopyroxene and amphibole. Despite the differences in petrography and major element composition, the identical shape of calculated REE patterns of liquid in equilibrium with clinopyroxenes indicates that the percolating melt in Ronda and Ojén shares a common source. However, unlike gabbros from the oceanic lithosphere that shows clinopyroxene in equilibrium with LREE-depleted MORB

  18. Sinfonevada: Dataset of Floristic diversity in Sierra Nevada forests (SE Spain).

    PubMed

    Pérez-Luque, Antonio Jesús; Bonet, Francisco Javier; Pérez-Pérez, Ramón; Rut Aspizua; Lorite, Juan; Zamora, Regino

    2014-01-01

    The Sinfonevada database is a forest inventory that contains information on the forest ecosystem in the Sierra Nevada mountains (SE Spain). The Sinfonevada dataset contains more than 7,500 occurrence records belonging to 270 taxa (24 of these threatened) from floristic inventories of the Sinfonevada Forest inventory. Expert field workers collected the information. The whole dataset underwent a quality control by botanists with broad expertise in Sierra Nevada flora. This floristic inventory was created to gather useful information for the proper management of Pinus plantations in Sierra Nevada. This is the only dataset that shows a comprehensive view of the forest flora in Sierra Nevada. This is the reason why it is being used to assess the biodiversity in the very dense pine plantations on this massif. With this dataset, managers have improved their ability to decide where to apply forest treatments in order to avoid biodiversity loss. The dataset forms part of the Sierra Nevada Global Change Observatory (OBSNEV), a long-term research project designed to compile socio-ecological information on the major ecosystem types in order to identify the impacts of global change in this area.

  19. Mineralogical evidence for lamproite magma mixing and storage at mantle depths: Socovos fault lamproites, SE Spain

    NASA Astrophysics Data System (ADS)

    Cambeses, A.; Garcia-Casco, A.; Scarrow, J. H.; Montero, P.; Pérez-Valera, L. A.; Bea, F.

    2016-12-01

    Detailed textural and mineral chemistry characterisation of lamproites from the Socovos fault zone, SE Spain Neogene Volcanic Province (NVP) combining X-ray element maps and LA-ICP-MS spot analyses has provided valuable information about mantle depth ultrapotassic magma mixing processes. Despite having similar whole-rock compositions, rocks emplaced in the Socovos fault are mineralogically varied: including type-A olivine-phlogopite lamproites; and type-B clinopyroxene-phlogopite lamproites. The Ol-lacking type-B predates Ol-bearing type-A by c. 2 million years. We propose that the mineralogical variations, which are representative of lamproites in the NVP as a whole, indicate mantle source heterogeneities. Major and trace element compositions of mineral phases suggest both metasomatised harzburgite and veined pyroxenite sources that were most likely closely spatially related. Thin section scale textural and compositional variations in mineral phases reveal heterogeneous mantle- and primitive magma-derived crystals. The variety of crystals points to interaction and mingling-mixing of ultrapotassic magma batches at mantle depths prior crustal emplacement. The mixing apparently occurred in a mantle melting zone with a channelised flow regime and localised magma chambers-reservoirs. Magma interaction was interrupted when the Socovos and other lithosphere-scale faults tore down to the mantle source region, triggering rapid ascent of the heterogeneous lamproite magma.

  20. Mesoscale climatic simulation of surface air temperature cooling by highly reflective greenhouses in SE Spain.

    PubMed

    Campra, Pablo; Millstein, Dev

    2013-01-01

    A long-term local cooling trend in surface air temperature has been monitored at the largest concentration of reflective greenhouses in the world, at the Province of Almeria, SE Spain, associated with a dramatic increase in surface albedo in the area. The availability of reliable long-term climatic field data at this site offers a unique opportunity to test the skill of mesoscale meteorological models describing and predicting the impacts of land use change on local climate. Using the Weather Research and Forecast (WRF) mesoscale model, we have run a sensitivity experiment to simulate the impact of the observed surface albedo change on monthly and annual surface air temperatures. The model output showed a mean annual cooling of 0.25 °C associated with a 0.09 albedo increase, and a reduction of 22.8 W m(-2) of net incoming solar radiation at surface. Mean reduction of summer daily maximum temperatures was 0.49 °C, with the largest single-day decrease equal to 1.3 °C. WRF output was evaluated and compared with observations. A mean annual warm bias (MBE) of 0.42 °C was estimated. High correlation coefficients (R(2) > 0.9) were found between modeled and observed values. This study has particular interest in the assessment of the potential for urban temperature cooling by cool roofs deployment projects, as well as in the evaluation of mesoscale climatic models performance.

  1. Sinfonevada: Dataset of Floristic diversity in Sierra Nevada forests (SE Spain)

    PubMed Central

    Pérez-Luque, Antonio Jesús; Bonet, Francisco Javier; Pérez-Pérez, Ramón; Rut Aspizua; Lorite, Juan; Zamora, Regino

    2014-01-01

    Abstract The Sinfonevada database is a forest inventory that contains information on the forest ecosystem in the Sierra Nevada mountains (SE Spain). The Sinfonevada dataset contains more than 7,500 occurrence records belonging to 270 taxa (24 of these threatened) from floristic inventories of the Sinfonevada Forest inventory. Expert field workers collected the information. The whole dataset underwent a quality control by botanists with broad expertise in Sierra Nevada flora. This floristic inventory was created to gather useful information for the proper management of Pinus plantations in Sierra Nevada. This is the only dataset that shows a comprehensive view of the forest flora in Sierra Nevada. This is the reason why it is being used to assess the biodiversity in the very dense pine plantations on this massif. With this dataset, managers have improved their ability to decide where to apply forest treatments in order to avoid biodiversity loss. The dataset forms part of the Sierra Nevada Global Change Observatory (OBSNEV), a long-term research project designed to compile socio-ecological information on the major ecosystem types in order to identify the impacts of global change in this area. PMID:24843285

  2. Metal bioaccumulation pattern by Cotylorhiza tuberculata (Cnidaria, Scyphozoa) in the Mar Menor coastal lagoon (SE Spain).

    PubMed

    Muñoz-Vera, Ana; García, Gregorio; García-Sánchez, Antonio

    2015-12-01

    Coastal lagoons are ecosystems highly vulnerable to human impacts because of their situation between terrestrial and marine environment. Mar Menor coastal lagoon is one of the largest lagoons of the Mediterranean Sea, placed in SE Spain and subjected to major human impacts, in particular the mining of metal sulphides. As a consequence, metal concentration in water column and sediments of this ecosystem is usually higher than in other areas. For monitoring ecosystem health, the present study has assessed the ability of Cotylorhiza tuberculata for bioaccumulating metals from sea water. Up to 65 individuals were sampled at 8 different sampling stations during the summer of 2012. Although the concentration values for different elements considered were moderate (Pb: 0.04-29.50 ppm, Zn: 2.27-93.44 ppm, Cd: 0-0.67 ppm, As: 0.56-130.31 ppm) by dry weight of the jellyfish tissues (bell and oral arms combined), bioconcentration levels in relation to seawater metal concentration were extremely high. In any case, the use or disposal of these organisms should consider their metal content because of their potential environmental and health implications.

  3. Carbon Balance in an Olive Orchard of SE Spain: Influence of Weed Cover

    NASA Astrophysics Data System (ADS)

    Sanchez-Canete, E. P.; Chamizo, S.; Serrano-Ortiz, P.; Lopez-Ballesteros, A.; Vicente-Vicente, J. L.; Kowalski, A. S.

    2016-12-01

    Agriculture is largely responsible for greenhouse gas emissions due to deforestation, land use changes and inadequate practices. High carbon (C) losses in agricultural lands caused by inadequate soil management entail a reduction of their C sequestration capacity and make agriculture more vulnerable to climate change impact. However, this trend can be potentially reversed if adequate agricultural practices are applied. Olive trees are one of the most widespread crops in the Mediterranean region, especially in Spain. Due to climate characteristics of the Mediterranean region and soils characterized by poor structure and low organic matter content, these crops are subject to environmental problems including erosion, soil compaction, and the loss of soil fertility that, indeed, can be aggravated by conventional practices such as intensive tillage. No-till agriculture and maintenance of the spontaneous resident vegetation cover (hereinafter, "weeds") have been applied in olive orchards in order to reduce erosion and increase soil organic C content. However, the role of these conservation practices in C balance at ecosystem scale has not been assessed so far. In this study, we analyzed the influence of weeds against weed removal via herbicide application on the net ecosystem CO2 exchange (NEE) in an olive orchard in Jaén (SE Spain), by using two eddy covariance towers during the hydrological year 2014-2015. We found that the presence of weeds increased net C uptake during winter and early spring. However, after weeds were mowed in April and kept on the soil, net C uptake decreased in this treatment due to an increase in soil respiration. Despite the lower net C uptake observed during late spring, the presence of weeds increased C fixation at annual scale. During the year of study, the weed removal practice decreased C uptake by 50% compared to the olive orchard where weeds were kept. We conclude that maintenance of weeds in olive groves has a positive effect on CO2

  4. The Internal Subbetic of the Velez Rubio area (SE Spain): Is it tectonically detached or not?

    NASA Astrophysics Data System (ADS)

    Sanz de Galdeano, Carlos; López Garrido, Angel Carlos; Andreo, Bartolomé

    2015-01-01

    The sierras of Maria and Maimon form part of the Internal Subbetic in the eastern part of the Betic Cordillera, in contact with the Internal Zone. Previous papers have interpreted the Internal Subbetic as being tectonically detached at its bottom, thrusting the Solana Fm., and moreover thrusting the Internal Zone. Nevertheless, the analysis of the structure of these sierras (with great development of folds), and that of the Sierra del Gigante, indicates that this detachment does not exist and, on the contrary, the structure is clearly rooted. Moreover, the general rectilinear trend of the contact between the Internal and External Zones leads to the interpretation that it in fact corresponds to a dextral transcurrent contact, this contention being supported by the analysis of minor faults. According to the age of the younger sediments involved (the Espejos and Solana Fms.), the main deformation processes occurred from the early Miocene and continued during the middle Miocene, at least in part. The structure and characteristics of the geologic evolution of this area are comparable to that of the Internal Subbetic (Penibetic) in the western part of the cordillera.

  5. Influence of local and regional Mediterranean meteorology on SO₂ ground-level concentrations in SE Spain.

    PubMed

    Santacatalina, Milagros; Carratalá, Adoración; Mantilla, Enrique

    2011-06-01

    This work presents the results of a 4-year study on sulfur dioxide (SO(2)) ground-level concentrations in an area of southeastern Spain, the L'Alacantí region, where the cement industry is important and coke use extends to other industries as well. The main source of SO(2) emissions in the area was found to be a the Lepold cement plant (one of the two cement plants in the area). The high levels of SO(2) probably extend back to 1920 when this plant began operations. Both local and Mediterranean-scale meteorological processes influence the SO(2) ground-level concentration and together explain the dispersion dynamics of this pollutant. The location and topography of the study zone result in NW Atlantic advections and E-SE sea breezes being the dominant atmospheric circulation patterns in the area. Under stable meteorological conditions, minor local circulations are also relevant to the SO(2) concentration levels. The high frequency of local circulations determines a concentration pattern that changes during the day, with impacts occurring preferentially in a W-NW direction from the source at midday (sea breeze and strong thermal mixture), and in a SE direction at night. This causes the SO(2) concentrations to present well-defined diurnal cycles with well-differentiated shapes depending on the location of the sampling station relative to the source. The dependence of SO(2) 10 min levels on the wind origin and speed throughout the day has been evaluated by studying statistical parameters including P95, P50 and arithmetic mean. Exceedances occur under specific dispersion conditions at distances less than 1 km from the source. However, the source is traceable at larger distances and the levels are higher than typical urban ones. P95 was used as an estimator of the occurrence of larger levels or impacts. Leeward of NW winds and the source, at night and in early morning, P95 levels are comprised between 30 and 55 µg m(-3). In contrast, with SE winds and at midday, P95

  6. ERT studies on tailings ponds of the Sierra Minera Cartagena-La Union, SE Spain (Invited)

    NASA Astrophysics Data System (ADS)

    Martinez-Pagan, P.; Faz-Cano, A.; Rosales-Aranda, M. R.

    2009-12-01

    The Sierra Minera Cartagena - La Union (SE Spain) is a huge area that has been mined for centuries. That mining extraction activity was particularly enormous in the second half of the twentieth century. By the early 1980’s almost all mineral deposits of this area had been depleted and the mineral processing plants had left 80 tailings ponds of different shape and height as a result of their activity. At the present, these former mining areas are close to important urban and industrial centers, where the tailings ponds are potential points of environmental and geotechnical concerns among others. In the 1972, there was also an important collapse of a tailings pond after a strong stormy event. Because of that, nowadays, there are several researcher groups working on the area with the goal of improving the environmental, geotechnical, safety, and use conditions of the tailings ponds. In this framework, the electrical resistivity tomography (ERT) method was used to obtain complementary information from the inner of the tailings ponds itself. Due to the high electrical resistivity contrast between the tailings and the hard-rock the geo-electrical methods became very useful in getting information about the bedrock geometry. In addition, where the tailing ponds have not been built up with a more complex interne structure (Figure 1) then it has been possible to obtain their construction history based on the grain distribution which is related in some extent to the electrical resistivity. In some cases, based on the fact of the presence of big cracks into the pond as pathways (Figure 2) where the mine acid waters are infiltrated easily, the use of ERT technique has proved its usefulness in highlighting them. Moreover, the ERT method can be an interesting tool in tailings ponds remediation works by delimiting the acid areas on the surface characterized by low electrical resistivity values.

  7. Plio-Pleistocene lacustrine evaporites of the Baza Basin (Betic Chain, SE Spain)

    NASA Astrophysics Data System (ADS)

    Gibert, Lluís; Ortí, Federico; Rosell, Laura

    2007-08-01

    The Baza Basin (the eastern part of the Guadix-Baza Basin, in SE Spain) underwent a significant evaporitic sedimentation in non-marine settings during the Plio-Pleistocene. The largest of these settings developed in the central part of the basin as a shallow, saline lake system, where abundant gypsum deposits occur (Benamaurel and Galera Gypsum units). This paper studies these deposits from the cartographic, stratigraphic, sedimentologic, petrographic and isotopic points of view. All the gypsum has been preserved as primary enabling a good characterization of the environmental conditions of the original precipitates. Three interconnected subenvironments or zones -inner, intermediate and marginal- are differentiated in this saline lake system. In the inner zone (shallow to relatively deeper central lake), a regular alternation of gypsum and carbonate laminae accumulated suggesting a seasonal regime. Many of the gypsum laminae display size-gradation (both reverse and symmetrical) indicating free precipitation in a stable brine body. In the intermediate zone (mosaic of shallow lakes), carbonate (dolomitic) beds formed in association with dark lutite levels, gypsum beds, and gypsum nodules and micronodules. Moreover, anoxic conditions developed in this zone, which resulted in the formation of native sulphur occurrences of economic value. In the marginal zone, the evaporitic deposits are developed only locally (the Galera Gypsum unit, in particular). The various gypsum lithofacies in these marginal deposits suggest the presence of a number of shallow to exposed settings (saline mudflat, saline marsh and gypsiferous pond). The isotopic composition ( δ34S, δ18O) of the gypsum samples is consistent with a Triassic origin of the sulphate as a result of chemical recycling. These data also suggest that a similar recycling mechanism operated in the saline lake system, where the gypsum sediments from the margins were coevally recycled towards the inner part. Both the

  8. Processes and Geomorphological Impacts of an Extreme Flash Flood Event in SE Spain

    NASA Astrophysics Data System (ADS)

    Hooke, J.

    2015-12-01

    A major flash flood event took place on 28 September, 2012 in SE Spain, resulting in 10 fatalities and much damage to infrastructure regionally. The flood affected long-term monitoring sites in two catchments in which morphological changes and flow dynamics of these ephemeral channels were being measured. Thus detailed data on channel state prior to the flood were available. The flood event in the Nogalte catchment was extreme in its peak flow, rate of rise and unit runoff. The catchment has steep relief and much bare soil under almond groves, resulting in high sediment supply. The channel is confined in places, but mostly wide and braided, composed of loose gravel and occupying much of the valley floor. Flow was spatially continuous, with high connectivity throughout the catchment. The flood effects were net depositional in the monitored sites, with massive sedimentation on the channel bars. Vegetation was destroyed. Bank erosion and destruction of embankments took place in some locations. Hydraulic calculations indicate very high velocities, stream power and Froude numbers. Modelling and field evidence demonstrate extremely high sediment competence and sediment loadings. The influence of the event dynamics on processes and net outcomes is discussed. The impacts are compared with other events in this and neighbouring catchments. Overall, the event in the Nogalte did not alter the morphology markedly in spite of its extreme characteristics. It is suggested that these valley floors are adapted to this type of flash flood but that flows of such force and magnitude need to be allowed for in management in such an environment.

  9. Lithofacies and water-body record of Messinian evaporites in Nijar Basin, SE Spain

    NASA Astrophysics Data System (ADS)

    Lu, Feng H.

    2006-06-01

    The depositional lithofacies and fabrics of Messinian evaporites have been studied to evaluate the palaeodepth of water body in Nijar Basin, SE Spain. The Nijar Messinian strata consist of three formations: Abad marls, Yesares evaporites, and Feos rocks. Gypsum deposits dominate the Yesares Formation and the basal Feos Formation. Six gypsum lithofacies have been identified including coarse twinned selenite, grass-like selenite, hemiradial to radial selenite, turbidite selenite in the Yesares Formation; and gypsum conglomerate, laminated gypsum, and hemiradial to radial selenite in the Feos Formation. The size of Yesares selenites decreases upward while carbonate content and trace-element abundance increase in each selenite bed and the whole formation, suggesting a shallowing-up sequence. These gypsum lithofacies were deposited in subaqueous environments commonly at 10-30 m and occasionally up to 100 m or deeper for the turbiditic selenites based on the interpretations of gypsum fabrics, marl intervals, basin configuration, and geochemistry. The sea level of Nijar Basin experienced two major drops with a magnitude of ˜ 40 m before and after the deposition of Yesares evaporites. However, the basin was never desiccated during the evaporite deposition and the change of sea level for the alternative deposition of gypsum beds and marl intervals was commonly around 50-80 m, probably resulting from the glacio-eustacy fluctuations. Feos gypsum reflects another evaporative event and is correlated to the "Upper Evaporite" while the Yesares selenite is correlated to the "Lower Evaporite" based on the interpretations of lithofacies, geochemistry, and sealevel change. As seawater in Nijar Basin was continuously supplied by the central Mediterranean basins and remained in subaqueous conditions during the Messinian salinity crisis, therefore, the desiccation theory needs to be reexamined.

  10. Risk assessment and restoration possibilities of some abandoned mining ponds in Murcia Region, SE Spain

    NASA Astrophysics Data System (ADS)

    Faz, Angel; Acosta, Jose A.; Martinez-Martinez, Silvia; Carmona, Dora M.; Zornoza, Raul; Kabas, Sebla; Bech, Jaume

    2010-05-01

    In Murcia Region, SE Spain, there are 85 tailing ponds due to intensive mining activities that occurred during last century, especially in Sierra Minera de Cartagena-La Union. Although mining activity was abandoned several decades ago, those tailing ponds with high amounts of heavy metals still remain in the area. The ponds, due to their composition and location, may create environmental risks of geochemical pollution, negatively affecting soil, water, and plant, animal, and human populations, as well as infrastructures. The main objective of this research is to evaluate the restoration possibilities of two representative mining ponds in order to minimize the risk for human and ecosystems. To achieve this objective, two tailing ponds generated by mining activities were selected, El Lirio and El Gorguel. These ponds are representative of the rest of existent ponds in Sierra Minera de Cartagena-La Unión, with similar problems and characteristics. Several techniques and studies were applied to the tailing ponds for their characterization, including: geophysics, geotechnics, geochemical, geological, hydrological, and vegetation studies. In addition, effects of particulate size in the distribution of heavy metals will be used to assess the risk of dispersion of these metals in finest particles. Once the ponds were characterized, they were divided in several sectors in order to apply different amendments (pig slurry and marble waste) to reduce the risk of metal mobility and improve soil quality for a future phytostabilization. It is known that organic amendments promote soil development processes, microbial diversity, and finally, soil ecosystem restoration to a state of self-sustainability. By comparing the results before and after applications we will be able to evaluate the effect of the different amendments on soil quality and their effectively on risk reduction. Finally, plant metal-tolerant species are used to restore vegetation in the ponds, thereby decreasing

  11. Spain.

    PubMed

    1985-03-01

    Spain is a constitutional monarchy with a population of 38.3 million growing at .5%/year. The most striking topographical features are the high plateaus and internal compartmentalization by mountain and river barriers. Nearly 3/4 of the country is arid. The Iberian peninsula was the scene of successive invasions and warfare for centuries. Phoenicians, Greeks, Carthaginians, Moors, Celts, Romans, and Visigoths all invaded at some time. The present language, religion, and laws stem from the Roman Period. The Reconquest from the North African Moors lasted over 700 years until they were driven out in 1492. The unification of present day Spain was complete by 1512. A period of dictatorial rule from 1923-31 ended with establishment of the Second Republic which saw increasing political polarization culminating in the Spanish Civil War. Franco's victory in 1939 was followed by official neutrality but pro-Axis policies during World War II. Spain's economy began to recover during the 1950s, but large scale modernization and development did not occur until the 1960s. Prince Juan Carlos de Borbon y Borbon, Franco's personally designated heir, assumed the title of king and chief of state with Franco's death in 1975. Franco's last prime minister was replaced in July 1976 in order to speed the pace of post-Franco liberalization. Spain's 1st parliamentary elections since 1936 were held in 1977, and a new constitution protecting human and civil rights and granting due process was overwhelmingly approved in 1978. The constitution also authorized creation of regional autonomous governments. By the mid-1970s, Spain had developed a strong and diversified industrial sector and a thriving tourist industry. From 1975-83, there were 8 years of double-digit inflation, an average growth rate of 1.5% in real terms, and an increase in unemployment from about 4.7% to 18.4%. By 1984 there was substantial improvement in inflation and the balance of payments. Goals of current government economic

  12. Amendments and mulches improve the biological quality of soils degraded by mining activities in SE Spain

    NASA Astrophysics Data System (ADS)

    Luna Ramos, Lourdes; Miralles Mellado, Isabel; Hernández Fernández, María Teresa; García Izquierdo, Carlos; Solé Benet, Albert

    2014-05-01

    Mining and quarrying activities generate negative visual impacts in the landscape and a loss of environmental quality. Substrate properties at the end of mining are in general not suitable for plant growth, even native ones. In an experimental soil restoration in limestone quarries from Sierra de Gádor (Almería), SE Spain, the effect of organic amendment (sewage sludge, compost from the organic fraction of domestic waste or non-amendment) combined or not with two different kind of mulches (fine gravel, chopped forest residue) was tested by triplicate in 5 x 5 m plots with the aim to improve soil/substrate properties and to reduce evaporation and erosion. In each experimental plot 75 native plants (Stipa tenacissima, Anthyllis terniflora and Anthyllis cytisoides) were planted. Effects of adding organic amendments and mulches on some soil microbiological and biochemical parameters (microbial biomass carbon, basal respiration and different enzymatic activities, such as dehydrogenase, phosphatase, β-glucosidase and urease) were analyzed 5 years after the start of the experiment. Vegetation growth was also monitored. The two-way ANOVA, using as factors amendment and mulch, showed a significant positive influence of organic amendments on microbial biomass (Cmic), basal respiration and some enzymatic activities related to the cycles of C and N. The highest values of these parameters were obtained with compost. The influence of the mulch factor and its interactions with the amendment factor on the measured variables did not follow a clear trend with respect the measured parameters. Mulching did not improved significantly (p<0.05) the positive effect of organic amendments on Cmic although Cmic values increased with the incorporation of "forest chopped residue" and decreased with gravel incorporation. In general, both type of mulch decreased or have no effect on the microbial activity detected in the amended soils, with the only exception of the forest chopped residue

  13. Micro CT characterization of a coastal mine tailings deposit, Portmán Bay, SE Spain

    NASA Astrophysics Data System (ADS)

    Frigola, Jaime; Cerdà-Domènech, Marc; Barriuso, Eduardo; Sanchez-Vidal, Anna; Amblas, David; Canals, Miquel

    2017-04-01

    Scanning of sediment cores by means of high-resolution non-destructive techniques provides researchers with huge amounts of highly valuable data allowing fast and detailed characterization of the materials. In the last decades several devoted instruments have been developed and applied to the study of sedimentary sequences, mainly multi-sensor core loggers (MSCL) for the physical properties and XRF core scanners for the chemical elemental composition. The geoscientific community started using computed tomography (CT) systems about two decades ago. These were mainly medical systems as dedicated instruments were essentially lacking by that time. The resolution of those medical systems was limited to several hundreds of micrometres voxel size. Micro computed tomography (micro-CT) systems have also spread into geoscientific research, although their limited workspace dimensions prevents their use for large objects, such as long sediment cores. Recently, a new micro-CT system, the MultiTom Core X-ray CT, conceived by University of Barcelona (UB) researchers and developed by X-ray Engineering, became operational. It is able of scanning sediment cores up to 1.5 m long, and allows adjustable resolutions from 300 microns down to 3-4 microns. The system is now installed at UB's CORELAB Laboratory for non-destructive analyses of geological materials. Here we present, as an example, the results of MultiTom scans of a set of sediment cores recovered offshore Portmán Bay, SE Spain, in order to characterize at very high-resolution the metal-enriched deposit generated after 33 years of direct discharge into the sea of mine tailings resulting from the exploitation of Pb and Zn ores. In total 52 short cores and 6 long gravity cores from the mine tailings infilled bay were scanned with the MultiTom system at a mean voxel resolution of 125 microns. The integrated study of micro-CT data allowed differentiating the main tailings units from deposits formed after disposal cessation

  14. Palaeoflood estimates of Pleistocene coarse grained river terrace landforms (Río Almanzora, SE Spain)

    NASA Astrophysics Data System (ADS)

    Stokes, Martin; Griffiths, James S.; Mather, Anne

    2012-05-01

    A series of palaeoflood estimation techniques are applied to an inset sequence of Middle to Late Pleistocene river terrace landforms associated with the Río Almanzora, SE Spain. The study area is a 7 km-long transverse reach, where 4 terrace levels (Level 1 = highest and oldest, Level 4 = lowest and youngest) document some 200 m of incision across an uplifted basement block during the Pleistocene. For the broader region, river terrace aggradation is attributed to increased sediment supply during glacial to interglacial transitions (Level 1 = Marine oxygen isotope stages [MOIS] 12/11, L2 = 10/9, L3 = 8/7 and L4 = 6/5). Within the transverse reach, terrace Levels 2, 3 and 4 are characterised by coarse boulder-rich gravels (Dmax = 2.5 m) organised into 3-5 m-high cross-beds. Level 4 is characterised by a series of km-scale abandoned meander loops, with Levels 2 and 3 showing evidence for similar degraded high sinuosity forms. The fluvial setting is interpreted as a braided river environment, with lateral and longitudinal gravel barforms. Using field-derived sedimentary (boulder size etc) and morphological (width, slope etc) features, flow competence- and regime-based methods were applied. Palaeoflood estimates varied from 40 to 2859 m3/s, with mean maximum discharges showing an increase through time (L2 = 278, L3 = 413, L4 = 1361 m3/s). Palaeoflood estimates were compared to flood events associated with the ephemeral modern Río Almanzora (catchment = 2500 km2) to establish whether palaeoflood values were reasonable estimations. A 46-year (1963-2009) modern flood gauge record shows infrequent flood events with discharges typically < 40 m3/s. A rare flood event in 1973 (5680 m3/s) provides an upper value for comparison with the palaeoflood estimates. Although estimates appear reasonable they should be considered as minimum values due to 1) some disparities between flow depths derived from the palaeoflood equations (0.7-4 m) and field-based evidence (3-5 m-high cross

  15. Salinity effect of irrigation with treated wastewater in basal soil respiration in SE of Spain

    NASA Astrophysics Data System (ADS)

    Morugan, A.; Garcia-Orenes, F.; Mataix-Solera, J.

    2012-04-01

    The use of treated wastewater for the irrigation of agricultural soils is an alternative to utilizing better-quality water, especially in semiarid regions where water shortage is a very serious problem. Wastewater use in agriculture is not a new practice, all over the world this reuse has been common practice for a long time, but the concept is of greater importance currently because of the global water crisis. Replacement of freshwater by treated wastewater is seen as an important conservation strategy contributing to agricultural production, substantial benefits can derive from using this nutrient-rich waste water but there can also be a negative impact. For this reason it is necessary to know precisely the composition of water before applying it to the soil in order to guarantee minimal impact in terms of contamination and salinization. In this work we have been studying, for more than three years, different parameters in calcareous soils irrigated with treated wastewater in an agricultural Mediterranean area located at Biar (Alicante, SE Spain), with a crop of grape (Vitis labrusca). Three types of waters were used for the irrigation of the soil: fresh water (control) (TC), and treated wastewater from secondary (T2) and tertiary treatment (T3). Three different doses of irrigation have been applied to fit the efficiency of the irrigation to the crop and soil type during the study period. A soil sampling was carried out every four months. We show the results of the evolution of basal soil respiration (BSR), and its relationship with other parameters. We observed a similar pattern of behavior for BSR between treatments, a decrease at the first eighteen months of irrigation and an increase at the end of study. In our study case, the variations of BSR obtained for all the treatments seem to be closely related to the dose and frequency of irrigation and the related soil wetting and drying cycles. However, the results showed a negative correlation between BSR and

  16. The stratigraphic record of the Messinian salinity crisis in the northern margin of the Bajo Segura Basin (SE Spain)

    NASA Astrophysics Data System (ADS)

    Soria, J. M.; Caracuel, J. E.; Yébenes, A.; Fernández, J.; Viseras, C.

    2005-08-01

    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 in a context of sea level highstand. The upper boundary of the MI Unit corresponds to the intra-Messinian unconformity, a lowstand erosional surface with palaeovalleys of 30 m deep generated by a sea level fall. Messinian Unit II (MII) comprises five correlative depositional systems (from fluvial to coastal) deposited during a new sea level highstand after a reflooding that followed the preceding lowstand. The upper boundary of Unit MII corresponds to the end-Messinian unconformity, which is another lowstand erosional surface with similar palaeovalleys to those of the intra-Messinian unconformity. Messinian Unit MIII forms the fluvial fill of some small incised palaeovalleys, developed during the end-Messinian lowstand. Over the end-Messinian unconformity lies the Pliocene Unit (P), which consists of four depositional systems superimposed in continuity. The first two (littoral and open marine) form a transgressive assemblage that fill the palaeovalley carved over the end-Messinian unconformity. The latter two (shallow marine to coastal in the lower part, and fluvial in the upper part) form a regressive prograding assemblage deposited in a highstand context, when the sea level reached its height in the early Pliocene. In relation to the Messinian salinity crisis, we propose that Unit MII is correlative to the evaporites deposited in the centre of the Bajo Segura Basin (San Miguel Gypsum Formation), corresponding to the marginal evaporites of the Mediterranean. Evaporitic sedimentation

  17. Fluid-rock interaction controlling clay-mineral crystallization in quartz-rich rocks and its influence on the seismicity of the Carboneras fault area (SE Spain)

    NASA Astrophysics Data System (ADS)

    Jimenez-Espinosa, R.; Abad, I.; Jimenez-Millan, J.; Lorite-Herrera, M.

    2009-04-01

    The Carboneras Fault zone is one of the longest fault in the Betic Cordillera (SE Spain) and it would be a good candidate to generate large magnitude earthquakes (Gracia et al., 2006). Seismicity in the region is characterised by low to moderate magnitude events, although large destructive earthquakes have occurred, which reveals significant earthquake and tsunami hazards (Masana et al., 2004). Due to the internal architecture of the fault zone, shear lenses of post-orogenic sediments of Miocene and Pliocene age including marls and sandstones sequences are juxtaposed to the predominant slaty gouges of the Alpine basement. Microcataclasites and gouges of the quartz-rich post-orogenic sediments are also developed as cm- to m-scale bands, allowing the comparison between the deformed materials and their protoliths. Red, yellow and white sandstones and their respective cataclasites can be identified. This communication is concerned with the clay mineral crystallization events in these materials and its possible influence on the seismicity model of the region. The presence of phyllosilicates in fault zones as either neoformed or inherited clays is commonly related with fluid circulation and a mechanically weak fault behaviour (e.g., Wang, 1984). A critical factor for the understanding of the mechanical role of clays in fault rocks is to determine the timing of formation of mineral assemblages and microstructure of fault rocks and protolith. The effects of post-faulting alteration limit inferences about fault behaviour that can be made from exhumed rocks. The Carboneras fault zone provides good opportunities to study mineral processes enhanced by deformation, given that it is located in a region of arid climate and shows outcroppings of quartzitic rocks included in slaty rocks. Combined XRD, optical microscopy and SEM analyses reveal that deformed quartzitic rocks are enriched in phyllosilicates, increasing especially the amount of chlorite. The samples strongly damaged

  18. Mineralogical study of stream waters and efflorescent salts in Sierra Minera, SE Spain

    NASA Astrophysics Data System (ADS)

    Pérez-Sirvent, Carmen; Garcia-Lorenzo, Maria luz; Martinez-Sanchez, Maria Jose; Hernandez, Carmen; Hernandez-Cordoba, Manuel

    2015-04-01

    Trace elements contained in the residues from mining and metallurgical operations are often dispersed by wind and/or water after their disposal. These areas have severe erosion problems caused by water run-off in which soil and mine spoil texture, landscape topography and regional and microclimate play an important role. Water pollution by dissolved metals in mining areas has mainly been associated with the oxidation of sulphide-bearing minerals exposed to weathering conditions, resulting in low quality effluents of acidic pH and containing a high level of dissolved metals. The studied area, Sierra Minera, is close to the mining region of La Unión (Murcia, SE Spain). This area constituted an important mining centre for more than 2500 years, ceasing activity in 1991. The ore deposits of this zone have iron, lead and zinc as the main metal components. Studied area showed a lot of contaminations sources, formed by mining steriles, waste piles and foundry residues. As a consequence of the long period of mining activity, large volumes of wastes were generated during the mineral concentration and smelting processes. Historically, these wastes were dumped into watercourses, filling riverbeds and contaminating their surroundings. 40 sediment samples were collected from the area affected by mining exploitations, and at increasing distances from the contamination sources in 4 zones In addition, 36 surficial water samples were collected after a rain episode The Zn and Fe content was determined by flame atomic absorption spectrometry (FAAS). The Pb and Cd content was determined by electrothermal atomization atomic absorption spectrometry (ETAAS). The As content was measured by atomic fluorescence spectrometry using an automated continuous flow hydride generation spectrometer and Al content was determined by ICP-MS. Mineralogical composition of the samples was made by X Ray Diffraction (XRD) analysis using Cu-Kα radiation with a PW3040 Philips Diffractometer. Zone A: Water

  19. Life expectancy in a western and immigrant receiving population (El Ejido, SE Spain).

    PubMed

    Luna, Francisco; García-Moro, Clara; Alonso, Verónica

    2007-12-01

    This study deals with the mortality pattern of El Ejido population, an agricultural Spanish community with a sub-tropical climate, located on the western Mediterranean coast (Andalusia). Based on the incorporation of modern agrarian techniques, this region has experienced a great economic development. Its demographic consequences were relevant, such as the arrival of immigrants throughout the second half of the twentieth century. The analysis of several demographic parameters shown in the abridged life table has revealed a small but non-random decrease of mortality during the last two decades of the past century. Furthermore, from the low value reached by the current entropy coefficient (H = 0.131), and the comparison of El Ejido life-expectancy at birth (e0) with Spain and Andalusia, we concluded that: a) The current mortality of El Ejido has approached a theoretical situation, where all deaths tend to take place at the age of 78.09 (its e0), and the death probability is very low at earlier ages. b) Some peculiar characteristics of its immigration as well as the high influence of the great public health system reached currently in Spain, reveal that El Ejido mortality does not depend on its remarkable immigration.

  20. Use of Biomass Ash as a stabilization agent for expansive marly soils (SE Spain)

    NASA Astrophysics Data System (ADS)

    Ureña, C.; Azañón, J. M.; Caro, J. M.; Irigaray, C.; Corpas, F.; Ramirez, A.; Rivas, F.; Salazar, L. M.; Mochón, I.

    2012-04-01

    In recent years, several biomass power plants have been installed in Southeastern Spain to reuse olive oil industry residues. This energy production tries to reduce the high costs associated with fossil fuels, but without entering into direct competition to traditional food crops. The waste management in these biomass energy plants is still an issue since there are non-flammable materials which remains after incineration in the form of ashes. In Southeastern Spain there is also a great amount of clayey and marly soils whose volume is very sensitive to changes in climate conditions, making them unsuitable for civil engineering. We propose the use of biomass ash (both fly ash and bottom ash) as a stabilization agent for expansive soils in order to improve the efficiency of construction processes by using locally available materials. In this work biomass ashes from a biomass power plant in Southeastern Spain have been used to stabilize 6 samples of local marly soil. Those 6 samples of expansive soil were mixed with different dosages of biomass ash (2%, 4% and 7%) to create 18 specimens of treated soil, which were submitted to Proctor, Atterberg Limits, pH and Free Swell Index tests, following Spanish Standards UNE by AENOR. X-Ray Diffraction (XRD) tests by powder method were also carried out, using a diffractometer Philips X'Pert-MPD. The results obtained for the original untreated marly soil were: PI = 34.6; Free Swell = 12.5; pH = 8. By adding biomass ash the value of the plasticity index (PI) became slightly lower although it was not low enough as to obtain a non-plastic soil (PI under 25). However, there were dramatical decreases of free swell index (FSI) after the stabilization treatment: FSI < 8.18 (2% biomass); FSI < 6.15 (4% biomass); FSI < 4.18 (7% biomass); These results suggest that treated soil is quite less susceptible than the original soil to moisture changes. The pH of the mixes after adding biomass ash rose from 8 to 11±1 leading to an alkaline

  1. Identification of the origin of salts in an agricultural area of SE Spain

    NASA Astrophysics Data System (ADS)

    Acosta, Jose A.; Faz, Angel; Kalbitz, Karsten; Jansen, Boris; Silvia, Martinez-Martinez

    2010-05-01

    In spite of soil salinity having been widely studied in many part of the world, origin of salinity has not been addresses in detail in some of the most productive agricultural areas of Europe (e.g. southeast of Spain). According to the European Commission, salinization affects about 1 to 3 million ha of the area of the European Union and Candidate Countries. In Europe, most of the salt-affected land surfaces are concentrated in the Mediterranean basin. In Spain, about 3% of the 3.5 million hectares of irrigated land are severely affected by salts and another 15% is at serious risk of imminent salinization. Due to the limited water resources in southeast of Spain, water with marginal quality is used for irrigation. The use of this water has led to degradation, reduction of the land's production capacity and soil salinization. The main aim of the present study was to identify the origin of the salts involved in such salinization, using classical and multivariable statistical techniques. In order to achieve this objective, surface soil samples were collected in January and July 2009 at 48 sites located in a representative lemon production area close to City of Murcia, covering a surface area of 44 km2. Soil pH, electrical conductivity, ionic composition, total organic matter, equivalent calcium carbonate, cation exchange capacity and particle size distribution were determined. The Pearson correlation coefficient, r, was used to measure the relationship between two quantitative variables and principal components analysis was used to study the correlations among anions and cations and their grouping into several factors. Results indicated that the high electrical conductivity found in the study area indeed comes from poor quality irrigation water used for agriculture. Anions and cations responsible of the salinity were chlorides, sulphates, calcium, magnesium and sodium. Mismanagement of water and traditional irrigation system resulted in salt build-up in the soil

  2. Pig manure application for remediation of mine soils in Murcia Province, SE Spain.

    PubMed

    Faz, A; Carmona, D M; Zanuzzi, A; Mermut, A R

    2008-08-31

    In southern Spain, specifically in Murcia Province, an increased pig population causes large amounts of slurry production that creates a very serious environmental concern. Our aim was to use this waste to reduce the acid mine drainage process, heavy metal mobilization, and to improve soil conditions to enhance plant establishment in mine soils. Pig manure, sewage sludge, and lime were used as soil amendments in a field experiment and in undisturbed soil column. Field experiments showed an increase in pH, total nitrogen, organic carbon, and carbonate contents; a reduction of diethylene-tetramine pentaacetic acid (DTPA)-- and water-extractable metals; and an improvement of plant establishment. The field studies showed that pig manure could be utilized to remediate polluted soils. Column studies in the laboratory showed that amendment of mine soil with pig manure initially increased soil pH from 2.21 to 6.34, promoted reduced conditions in the surface soil, and decreased the metal mobility. After 21 weeks, while the leachate was slightly acidic, however, the mobility of metals was substantially low. Additions of 7 and 14% of pig manure were insufficient to maintain a neutral pH in the leachate. Therefore, continuous application of the pig manure may be advised.

  3. The role of desalinisation to address aquifer overdraft in SE Spain.

    PubMed

    Martínez-Granados, David; Calatrava, Javier

    2014-11-01

    Aquifer overdraft is a major environmental and water management problem in Southeast Spain. In some areas, availability of desalinised seawater resources is being expanding, which provides an opportunity to address this problem at a lower social and economic cost. We analyse the economic impact of using several instruments to address the problem of non-renewable groundwater pumping in the aquifers of the Guadalentín basin: an environmental tax on groundwater use, the buyback of groundwater rights and the subsidization of desalinised resources. Their impact is assessed using a mathematical programming model that maximises the farm net margin resulting from the use of the available water resources for irrigation in the area. Our results show that, in the current situation of water availability, all the alternatives have significant economic impacts. Moreover, the first two alternatives would be unfeasible from a political point of view. The existence of abundant, though expensive, desalinised water resources in the foreseen future would reduce, but not eliminate, the negative economic impact of such instruments. Furthermore, water demand is so high in this area that even strongly subsidising desalinised water in exchange for reducing the use of groundwater would not allow to eliminate aquifer overdraft. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Heavy metals relationship in arable and greenhouse soils of SE Spain using a geostatistical analysis

    NASA Astrophysics Data System (ADS)

    Gil, Carlos; Joaquin Ramos-Miras, Jose; Rodríguez Martín, Jose Antonio; Boluda, Rafael; Roca, Núria; Bech, Jaume

    2013-04-01

    This study compares heavy metals contents and the main edaphic parameters in greenhouse soils from the W Almería region one of the most productive agricultural systems in Europe, with agricultural soils (arable soils) in western Andalusia, SW Spain. Heavy metals input in agricultural soils mainly occur through pesticides and phytosanitary control products. The hazardousness of the studied elements (Cr, Ni, Pb, Cu, Zn and Cd) is particularly relevant in soils used for intensive greenhouse farming where such agricultural practices, which centre on maximising production, end up with products that finally enter the human food chain directly. Here we explore a total of 199 greenhouse soils and 142 arable soils, representing two scales of variation in this Mediterranean area. Despite their similar edaphic characteristics, the main differences between arable soils and greenhouse soils lie in nutrients contents (P and K) and in certain heavy metals (Cd, Pb and Zn), which reflect widespread use of pesticides in greenhouse farming. One of the most toxic metals is Cd given its mobility, whose concentrations triple in greenhouse soils, although it does not exceed the limits set by Spanish legislation. We conclude that despite anthropic heavy metals input, the association patterns of these elements were similar on the two spatial variability scales. Cd, Pb and Zn contents, and partly those of Cu, are related with agricultural practices. On the short spatial scale, grouping these heavy metals shows very high contents in greenhouse soils in the central northern area of the W Almería region. On the other hand, the associations of Cr and Ni suggest a lithogenic influence combined with a pedogenic effect on spatial maps. This natural origin input becomes more marked on the long spatial scale (arable soils) where the main Cr and Ni contents are found in the vicinity of the Gádor Mountain Range.

  5. Pliocene Transgression in the Western Mediterranean Sea: Strontium Isotopes from Cuevas Del Almanzora (Se Spain)

    NASA Astrophysics Data System (ADS)

    Müller, Daniel W.

    1993-02-01

    The deposition of marine sediments in the deep Mediterranean basins following the Messinian salinity crisis ("Zanclean Deluge") began at 4.9 Ma and continued until normal marine conditions prevailed at 4.6 Ma. The Betic Strait of southeast Spain, the Rif Strait of northern Morocco, and the Strait of Gibraltar have been postulated as possible entry ways for the marine waters into the Mediterranean. Two possible explanations have been offered for the timing of the deposition of marine hemipelagic marls in the Vera Basin (Cuevas del Almanzora section) within the Betic Strait: (1) early Pliocene, representing the "Zanclean Deluge" (Cita et al., 1980), (2) Messinian (˜5.7 Ma), representing the last marine stage before the Messinian salinity crisis (Benson and Rakic-El Bied, 1991; Benson et al., 1991). The strontium isotopic ratio on mixed assemblages of foraminifers from these marine marls was determined in order to assess their ages. The average 87Sr/86Sr (0.709033±24) of the seven measured samples is, compared to the base of the Miocene/Pliocene boundary stratotype at Capo Rossello, Sicily, higher by 38 × 10-6 and yields an age of 4.6±0.5 Ma when compared to the established open ocean Sr seawater curve. The determined age indicates that (1) the first 3.6 m of marine deposits of the Cuevas del Almanzora section sensu Cita et al. (1980) including the passage zone are Pliocene, (2) the earliest marine Pliocene might not be represented at Cuevas del Almanzora indicating that this marginal basin at the edge of the Mediterranean Sea, yet within the former Betic Strait, was filled progressively by a marine transgression originating from the Mediterranean Sea around 4.6 Ma. The absence of lowermost Pliocene sediments could suggest that the Betic Strait did not serve as a conduit for the water masses entering the Mediterranean basins during the early Pliocene; and (3) the presence of an early evolutionary stage of Globorotalia margaritae in the Moroccan Bou Regreg section

  6. Seismic microzonation and velocity models of El Ejido area (SE Spain) from the diffuse-field H/V method

    NASA Astrophysics Data System (ADS)

    García-Jerez, Antonio; Seivane, Helena; Navarro, Manuel; Piña-Flores, José; Luzón, Francisco; Vidal, Francisco; Posadas, Antonio M.; Aranda, Carolina

    2016-04-01

    El Ejido town is located in the Campo de Dalías coastal plain (Almería province, SE Spain), emplaced in one of the most seismically active regions of Spain. The municipality has 84000 inhabitants and presented a high growth rate during the last twenty years. The most recent intense seismic activity occurred close to this town was in 1993 and 1994, with events of Mb = 4.9 and Mb = 5.0, respectively. To provide a basis for site-specific hazard analysis, we first carried out a seismic microzonation of this town in terms of predominant periods and geotechnical properties. The predominant periods map was obtained from ambient noise observations on a grid of 250 x 250 m in the main urban area, and sparser measurements on the outskirts. These broad-band records, of about 20 minutes long each, were analyzed by using the horizontal-to-vertical spectral ratio technique (H/V). Dispersion curves obtained from two array measurements of ambient noise and borehole data provided additional geophysical information. All the surveyed points in the town were found to have relatively long predominant periods ranging from 0.8 to 2.3 s and growing towards the SE. Secondary high-frequency (> 2Hz) peaks were found at about the 10% of the points only. On the other hand, Vs30 values of 550 - 650 m/s were estimated from the array records, corresponding to cemented sediments and medium-hard rocks. The local S-wave velocity structure has been inverted from the H/V curves for a subset of the measurement sites. We used an innovative full-wavefield method based on the diffuse-wavefield approximation (Sánchez-Sesma et al., 2011) combined with the simulated annealing algorithm. Shallow seismic velocities and deep boreholes data were used as constraints. The results show that the low-frequency resonances are related with the impedance contrast between several hundred meters of medium-hard sedimentary rocks (marls and calcarenites) with the stiffer basement of the basin, which dips to the SE. These

  7. Amino acid racemization dating of Upper Pleistocene - Holocene terrestrial gastropods from a Mediterranean region (Murcia, SE Spain)

    NASA Astrophysics Data System (ADS)

    Garcia-Mayordomo, Julian; Ortiz, Jose E.; Torres, Trinidad; Insua-Arevalo, Juan M.; Martinez-Diaz, Jose J.; Altolaguirre, Yul; Canales-Fernandez, Maria L.; Martin-Banda, Raquel

    2014-05-01

    The amino acid racemization method has become a widely used geochronological tool for dating Quaternary deposits. The method is based on the fact that living organisms contain only L-amino acids which gradually racemize into D-amino acids after death. Thus, the D/L ratio increases with time after death until it is equal to 1, that is, when equilibrium is reached. Gastropod shells are particularly useful for amino acid racemization dating. Because the amino acid racemization method is not a numerical dating method in isolation, it needs to be calibrated, mainly with radiometric dating methods. The racemization process is genus- and temperature-dependent. In this work we present a preliminary analysis that compares the radiometric age estimated from different dating methods of a number of gastropods recovered in localities from Murcia (Southeastern Spain), with the age obtained through the amino acid racemization method. Taking advantage of recent paleoseismological research in the Murcia region (SE Spain), 28 gastropods specimens were collected from different trenches dug in young Quaternary alluvial deposits. The specimens were subsequently classified and then analyzed according to the standards protocols of the Biomolecular Stratigraphy Laboratory (UPM, Madrid School of Mines). The species found were Otala lactea, Iberus gualterianus, Sphincterochila candidissima and Theba pisana. The D/L ratios of aspartic acid, leucine, phenylalanine and glutamic acid were determined, and the corresponding average age of each specimen was calculated introducing the D/L values in the age calculation algorithm of Torres et al. (1997) for gastropods of central and southern Spain. The racemization age for each locality was then compared to the radiometric age of the deposit where the specimens were collected. To this respect, the samples were classified in different groups considering the reliability on the age control method. The most reliable sample consists only on dates obtained

  8. Estimation of the tectonic slip-rate from Quaternary lacustrine facies within the intraplate Albacete province (SE of Spain)

    USGS Publications Warehouse

    Rodriguez-Pascua, M. A.; Bischoff, J.; Garduno-Monroy, Victor H.; Pérez-López, R.; Giner-Robles, J.L.; Israde-Alcántara, I.; Calvo, J.P.; Williams, Ross W.

    2009-01-01

    The Quaternary lacustrine basin of Cordovilla (CB) represents one of the most active tectonic areas of the Prebetic Zone (Albacete, SE of Spain). The Quaternary sedimentary deposits of this basin are mainly endoreic lacustrine carbonate and alluvial deposits, developed in a semi-arid climate (Pleistocene-present). The basin is a NW-SE-elongated graben bounded by a major right-lateral oblique-fault, the Pozohondo Fault. This fault trends NW-SE, with an approximate trace of 55 km, and is composed of various segments which are identified by fault scarps. In order to establish the slip-rate of the most active segment of the Pozohondo Fault, called the Cordovilla segment, we carried out a detailed study of the affected Quaternary lacustrine deposits. We found that the lacustrine facies could be related to episodic moderate paleoearthquakes. The slip-rate is calculated to be 0.05 and 0.09 mm/yr, using radiometric dating for the vertical offsets of the lacustrine facies. A trenching study at the northern part of the Cordovilla segment revealed two events caused by paleoearthquakes, with the most recent expressed as an oblique-fault off-setting a poorly-developed soil. The magnitude of the last event was greater than 6, using various empirical relationships for the fault displacement and the surface-length rupture. We estimate episodic activity across the Cordovilla segment, to be characterized by moderate-sized paleoearthquakes (M6), which is in agreement with the tectonic context of an intraplate zone of the Iberian plate. ?? 2009 Elsevier B.V.

  9. Estimation of the tectonic slip-rate from Quaternary lacustrine facies within the intraplate Albacete province (SE of Spain)

    NASA Astrophysics Data System (ADS)

    Rodríguez-Pascua, M. A.; Bischoff, J.; Garduño-Monroy, V. H.; Pérez-López, R.; Giner-Robles, J. L.; Israde-Alcántara, I.; Calvo, J. P.; Williams, R. W.

    2009-12-01

    The Quaternary lacustrine basin of Cordovilla (CB) represents one of the most active tectonic areas of the Prebetic Zone (Albacete, SE of Spain). The Quaternary sedimentary deposits of this basin are mainly endoreic lacustrine carbonate and alluvial deposits, developed in a semi-arid climate (Pleistocene-present). The basin is a NW-SE-elongated graben bounded by a major right-lateral oblique-fault, the Pozohondo Fault. This fault trends NW-SE, with an approximate trace of 55 km, and is composed of various segments which are identified by fault scarps. In order to establish the slip-rate of the most active segment of the Pozohondo Fault, called the Cordovilla segment, we carried out a detailed study of the affected Quaternary lacustrine deposits. We found that the lacustrine facies could be related to episodic moderate paleoearthquakes. The slip-rate is calculated to be 0.05 and 0.09 mm/yr, using radiometric dating for the vertical offsets of the lacustrine facies. A trenching study at the northern part of the Cordovilla segment revealed two events caused by paleoearthquakes, with the most recent expressed as an oblique-fault off-setting a poorly-developed soil. The magnitude of the last event was greater than 6, using various empirical relationships for the fault displacement and the surface-length rupture. We estimate episodic activity across the Cordovilla segment, to be characterized by moderate-sized paleoearthquakes (M6), which is in agreement with the tectonic context of an intraplate zone of the Iberian plate.

  10. Experimental studies of supercritical bedforms applied to coarse-grained turbidite deposits of the Tabernas Basin (SE Spain, late Miocene)

    NASA Astrophysics Data System (ADS)

    Cartigny, Matthieu; Postma, George; Kleverlaan, Kick

    2014-05-01

    Modern submarine canyon floors are often covered with bedform patterns linked to supercritical turbidity currents, while recognition of sedimentary structures associated with such bedforms in outcrops are rare. On the basis of experimental work on bed morphodynamics and flow structure of high-density turbidity currents, a 3-dimensional bedform stability diagram and related sedimentary facies diagram have been constructed. To allow scaling of this diagram to natural flows, four non-dimensional parameters are used: 1) densimetric Froude number, 2) modified mobility parameter, 3) dimensionless grain size and 4) basal sediment concentration. Each bedform and basal sediment concentration is then linked to a characteristic facies type. Numerical and theoretical models from the literature and observations from modern turbidite depositional systems are used to estimate characteristic sizes of the bedforms for different flow types. The model is applied to the turbidite fan systems of the Tabernas Basin (SE Spain, late Miocene) and discussed along existing classical models of high density turbidity current deposits. It is concluded that the vertical sequence of supercritical bedforms have been described in these models, yet to date have never been recognized as bedforms in outcrop, presumably because of their large size that easily exceeds the dimensions of commonly available outcrop. On the basis both experimental work and outcrop studies in the Tabernas Basin (SE Spain) a conceptual three-dimensional bedform diagram for recognition of cyclic steps in outcrop is constructed. Experimental data indicates that depositional processes on the stoss-side of a cyclic step are controlled by hydraulic jump, which temporarily stalls the flow and by subsequent waxing of the flow up to supercritical again. The hydraulic jump produces large scours with soft sediment deformation (flames) preserved in Bouma Ta, while near horizontal, massive to stratified top-cut-out turbidite beds are

  11. Biophysical and socioeconomic impacts of soil and water conservation measures. An evaluation of Sustainable Land Management in SE Spain.

    NASA Astrophysics Data System (ADS)

    de Vente, J.; Solé-Benet, A.; López, J.; Boix-Fayos, C.

    2012-04-01

    In close collaboration with stakeholders promising soil and water conservation measures were selected as part of the EU funded DESIRE project. These measures were monitored for nearly three years at an experimental farm in the upper Guadalentin (SE-Spain). Four Sustainable Land Management (SLM) measures were implemented on rainfed almonds: a) reduced tillage, b) green manure, c) straw mulch, d) traditional water harvesting. A fifth measure (e) reduced tillage of cereals, was compared to conventional mouldboard tillage. Here, we present monitoring results according to biophysical and socioeconomic criteria. SLM measures a, b and e, aim to reduce soil and water loss through runoff. Therefore, for each measure three replica erosion-runoff plots and a control plot were installed to monitor soil and water loss and soil moisture content at two depths. SLM measures c and d aim to increase soil water content by preventing soil evaporation and adding additional water by water harvesting respectively. In these fields, the volume of harvested water was registered and soil water content was monitored. In all experiments, farm operation costs and crop harvest were monitored as well. In the almond fields, green manure and reduced tillage significantly reduced soil and water loss as compared to the control plot with normal tillage operations. Also for the cereal field, results show lower erosion rates under reduced tillage as compared to traditional tillage operation. In two successive years, the highest almond harvest was found in the field with water harvesting (d), followed by the green manure field (b), though no significant differences were found in soil water content with their control plots. Mulching did not show a significant effect on soil water content or harvest. Four of the selected SLM options showed a positive effect on the protection of soil and water resources, and were beneficial for crop yield. Whereas, reduced tillage also results in lower production costs, the

  12. Climate change adaptation via targeted ecosystem service provision: a sustainable land management strategy for the Segura catchment (SE Spain)

    NASA Astrophysics Data System (ADS)

    Zagaria, Cecilia; de Vente, Joris; Perez-Cutillas, Pedro

    2014-05-01

    Topical research investigating climate, land-use and management scenarios in the Segura catchment (SE Spain), depicts a landscape at high-risk of, quite literally, deserting agriculture. Land degradation in the semi-arid region of SE Spain is characterized by water shortage, high erosion rates and salinization, increasingly exacerbated by climatic changes, scarce vegetation cover and detrimental farming practices. Future climate scenarios predict increases in aridity, variability and intensity of rainfall events, leading to increasing pressure on scarce soil and water resources. This study conceptualized the impending crisis of agro-ecological systems of the Segura basin (18800 km2) as a crisis of ecosystem service deterioration. In light of existing land degradation drivers and future climate scenarios, the potential of Sustainable Land Management (SLM) strategies was evaluated to target three priority ecosystem services (water provision, sediment retention and carbon sequestration) as a means to achieve climate change adaptation and mitigation. A preceding thorough process of stakeholder engagement (as part of the EU funded DESIRE project) indicated five SLM technologies for potential implementation, all with a focus upon reducing soil erosion, increasing soil water holding capacity and soil organic matter content. These technologies have been tested for over four years in local experimental field plots, and have provided results on the local effects upon individual environmental parameters. Despite the growing emphasis witnessed in literature upon the context-specificity which characterizes adaptation solutions, the frequent analysis at the field scale is limited in both scope and utility. There is a need to investigate the effects of adaptive SLM solutions at wider, regional scales. Thus, this study modeled the cumulative effect of each of the five selected SLM technologies with InVEST, a spatial analyst tool designed for ecosystem service quantification and

  13. Analysis of groundwater mining in two carbonate aquifers in Sierra de Estepa (SE Spain) based on hydrodynamic and hydrochemical data

    NASA Astrophysics Data System (ADS)

    Martos-Rosillo, Sergio; Rodríguez-Rodríguez, Miguel; Moral, Francisco; Cruz-Sanjulián, José Javier; Rubio, Juan Carlos

    2009-11-01

    The carbonate aquifers of Lora and Mingo form part of the hydrogeological unit of Sierra de Estepa (SE Spain). By means of time series analysis and a 1D numerical groundwater model, groundwater exploitation was quantified and the mean annual recharge in both systems was estimated (2001-2004). During this period, the Lora and Mingo aquifers received an average groundwater recharge of 0.29 × 106 m3/year and 0.14 × 106 m3/year, respectively, whereas an average of 0.34 × 106 m3/year and 0.21 × 106 m3/year, respectively, was extracted. These conditions led to a conspicuous lowering of the water table in both systems. In addition, the analysis of the evolution of the main hydrogeochemical parameters of the groundwater showed that the increased pumping rates produced an increase in total dissolved solids, and chloride and sodium ions in both aquifers. In the case of the Lora aquifer, the only ion that presented decreased levels was nitrate. The results show that groundwater pumping in both aquifers should not exceed the mean annual recharge of 0.29 × 106 m3/year and 0.14 × 106 m3/year in the Lora and Mingo aquifers, respectively. Nevertheless, it would be advisable to reduce pumping rates to below these values in order to restore piezometric levels and improve groundwater quality for different uses in the future.

  14. Flow in the western Mediterranean shallow mantle: Insights from xenoliths in Pliocene alkali basalts from SE Iberia (eastern Betics, Spain)

    NASA Astrophysics Data System (ADS)

    Hidas, Károly; Konc, Zoltán.; Garrido, Carlos J.; Tommasi, Andréa.; Vauchez, Alain; Padrón-Navarta, José Alberto; Marchesi, Claudio; Booth-Rea, Guillermo; Acosta-Vigil, Antonio; Szabó, Csaba; Varas-Reus, María. Isabel; Gervilla, Fernando

    2016-11-01

    Mantle xenoliths in Pliocene alkali basalts of the eastern Betics (SE Iberia, Spain) are spinel ± plagioclase lherzolite, with minor harzburgite and wehrlite, displaying porphyroclastic or equigranular textures. Equigranular peridotites have olivine crystal preferred orientation (CPO) patterns similar to those of porphyroclastic xenoliths but slightly more dispersed. Olivine CPO shows [100]-fiber patterns characterized by strong alignment of [100]-axes subparallel to the stretching lineation and a girdle distribution of [010]-axes normal to it. This pattern is consistent with simple shear or transtensional deformation accommodated by dislocation creep. One xenolith provides evidence for synkinematic reactive percolation of subduction-related Si-rich melts/fluids that resulted in oriented crystallization of orthopyroxene. Despite a seemingly undeformed microstructure, the CPO in orthopyroxenite veins in composite xenoliths is identical to those of pyroxenes in the host peridotite, suggesting late-kinematic crystallization. Based on these observations, we propose that the annealing producing the equigranular microstructures was triggered by melt percolation in the shallow subcontinental lithospheric mantle coeval to the late Neogene formation of veins in composite xenoliths. Calculated seismic properties are characterized by fast propagation of P waves and polarization of fast S waves parallel to olivine [100]-axis (stretching lineation). These data are compatible with present-day seismic anisotropy observations in SE Iberia if the foliations in the lithospheric mantle are steeply dipping and lineations are subhorizontal with ENE strike, implying dominantly horizontal mantle flow in the ENE-WSW direction within vertical planes, that is, subparallel to the paleo-Iberian margin. The measured anisotropy could thus reflect a lithospheric fabric due to strike-slip deformation in the late Miocene in the context of WSW tearing of the subducted south Iberian margin

  15. Pb, Cd, As, and Se concentrations in livers of dead wild birds from the Ebro Delta, Spain

    SciTech Connect

    Guitart, R.; Mateo, R.; Cerradelo, S.; Puig-Casado, P. Autonomous Univ., Bellaterra ); Torra, M.; To-Figueras, J. )

    1994-08-01

    Wild bird populations are susceptible to the environmental presence of toxic elements and substances, especially those that are non-degradable and tend to concentrate through the food chain. Monitoring of such substances in selected bird species could be useful to evaluate the health condition of the species involved and to assess contamination in the ecosystem. One of the most important wild bird sanctuaries of Europe, the Ebro Delta, is situated in NE Spain. The Ebro Delta is an alluvial plain of about 32,000 ha. Because of its special hydrological conditions and geographical situation, the Ebro Delta supports an important and diverse bird population, estimated at 180,000 in the winter period, constituting 311 different species. Most of the Ebro Delta's surface is dedicated to agriculture, principally rice, also serving as an excellent wild bird habitat. Accordingly, agricultural pesticides could be a major problem for wildlife. But in the last few decades the Ebro River and the Tarragona coast have also undergone considerable industrial development. The area is now facing environmental threats by industrial activities, and the ecosystem is becoming contaminated with heavy metals, petroleum hydrocarbons and PCBS. Heavy metal concentrations in marine organisms have been reported, but metal and metalloid concentrations in birds have not been available. This study monitors lead (Pb), cadmium (Cd), arsenic (As) and selenium (Se) concentrations in bird livers from diverse trophic levels in the Ebro Delta. Pb, Cd and As are well recognized as toxic elements, while Se, although causing well known deleterious effects for humans and domestic animals, has only recently been recognized as toxic for aquatic birds. The determination of contaminant loads in several avian species would be useful to control and prevent, when possible, pathological conditions derived from toxic levels of these contaminants for wild bird populations living in the Ebro Delta. 10 refs., 2 tabs.

  16. Erosion and stabilisation sequences in relation to base level changes in the El Cautivo badlands, SE Spain

    NASA Astrophysics Data System (ADS)

    Alexander, R. W.; Calvo-Cases, A.; Arnau-Rosalén, E.; Mather, A. E.; Lázaro-Suau, R.

    2008-08-01

    The complex multiple-age badlands at El Cautivo are cut in upper Miocene marls of the uplifted and dissected Tabernas Basin, Almería, in semi-arid SE Spain. Previous work identified six episodes of erosion and subsequent stabilisation, with ages ranging from the late Pleistocene to the present day. This paper uses newly-acquired digital elevation models, orthorectified aerial photographs, and field survey data to illustrate the development sequence of a series of gullies which drain into the Rambla de Tabernas. Changing drainage directions and phases of incision and stabilisation are related to the filling and subsequent dissection of the Tabernas lower lake sediments, differential material strengths, changing process mixes on hillslopes and, in more recent times, land-use changes. We propose that the erosional phases differed considerably in both time-span and depth of incision. A long period of stability during the existence of the lake led to extensive pediment development in the area. Subsequent incision into the lake sediments by the Rambla de Tabernas produced a limited amount of localised pediment incision in the tributary catchment. Subsequent aggradation occurred in the lower reaches of gullies when incision by the Rambla de Tabernas reached the underlying bedrock. Following incision through the lip of the lake the Rambla de Tabernas cut rapidly into the bedrock leading to an altered drainage direction in the tributary catchments and the major phase of badland development visible today. Stabilisation of the pediments and some of the north-facing slopes occurred subsequently. Increased sediment loads, caused by climatic shift, a change in land use, or both, gave rise to a later phase of valley fill in the gullies. The modern channels have reduced this fill to isolated terrace benches and there are also localised remnants of a lower, more recent fill. Whilst supporting the general interpretation of the site's development by Alexander et al. [Alexander, R

  17. Influence of sustainable irrigation regimes and agricultural practices on the soil CO2 fluxes from olive groves in SE Spain

    NASA Astrophysics Data System (ADS)

    Marañón-Jiménez, Sara; Serrano-Ortíz, Penelope; Vicente-Vicente, Jose Luis; Chamizo, Sonia; Kowalski, Andrew S.

    2017-04-01

    Olive (Olea europaea) is the dominant agriculture plantation in Spain and its main product, olive oil, is vital to the economy of Mediterranean countries. Given the extensive surface dedicated to olive plantations, olive groves can potentially sequester large amounts of carbon and contribute to mitigate climate change. Their potential for carbon sequestration will, however, largely depend on the management and irrigation practices in the olive grove. Although soil respiration is the main path of C release from the terrestrial ecosystems to the atmosphere and a suitable indicator of soil health and fertility, the interaction of agricultural management practices with irrigation regimes on soil CO2 fluxes have not been assessed yet. Here we investigate the influence of the presence of herbaceous cover, use of artificial fertilizers and their interaction with the irrigation regime on the CO2 emission from the soil to the atmosphere. For this, the three agricultural management treatments were established in replicated plots in an olive grove in the SE of Spain: presence of herbaceous cover ("H"), exclusion of herbaceous cover by using herbicides ("NH"), and exclusion of herbaceous cover along with addition of artificial fertilizers (0.55 kg m-2 year-1 of N, P, K solid fertilizer in the proportion 20:10:10, "NHF"). Within each management treatment, three irrigation regimes were also implemented in a randomized design: no-irrigation ("NO") or rain fed, full irrigation (224 l week-1 per olive tree, "MAX"), and a 50% restriction (112 l week-1 per olive tree, "MED"). Soil respiration was measured every 2-3 weeks at 1, 3, and 5 meters from each olive tree together with soil temperature and soil moisture in order to account for the spatial and seasonal variability over the year. Soil respiration was higher when herbaceous cover was present compared to the herbaceous exclusion, whereas the addition of fertilizer did not exert any significant effect. Although the different

  18. Long-term erosion rate measurements in gypsum caves of Sorbas (SE Spain) by the Micro-Erosion Meter method

    NASA Astrophysics Data System (ADS)

    Sanna, Laura; De Waele, Jo; Calaforra, José Maria; Forti, Paolo

    2015-01-01

    The present work deals with the results of long-term micro-erosion measurements in the most important gypsum cave of Spain, the Cueva del Agua (Sorbas, Almeria, SE Spain). Nineteen MEM stations were positioned in 1992 in a wide range of morphological and environmental settings (gypsum floors and walls, carbonate speleothems, dry conduits and vadose passages) inside and outside the cave, on gypsum and carbonate bedrocks and exposed to variable degree of humidity, different air flow and hydrodynamic conditions. Four different sets of stations have been investigated: (1) the main cave entrance (Las Viñicas spring); (2) the main river passage; (3) the abandoned Laboratory tunnel; and (4) the external gypsum surface. Data over a period of about 18 years are available. The average lowering rates vary from 0.014 to 0.016 mm yr- 1 near the main entrance and in the Laboratory tunnel, to 0.022 mm - 1 on gypsum floors and 0.028 mm yr- 1 on carbonate flowstones. The denudation data from the external gypsum stations are quite regular with a rate of 0.170 mm yr- 1. The observations allowed the collecting of important information concerning the feeding of the karst aquifer not only by infiltrating rainwater, but under present climate conditions also by water condensation of moist air flow. This contribution to the overall karst processes in the Cueva del Agua basin represents over 20% of the total chemical dissolution of the karst area and more than 50% of the speleogenetically removed gypsum in the cave system, thus representing all but a secondary role in speleogenesis. Condensation-corrosion is most active along the medium walls, being slower at the roof and almost absent close to the floor. This creates typical corrosion morphologies such as cupola, while gypsum flowers develop where evaporation dominates. This approach also shows quantitatively the morphological implications of condensation-corrosion processes in gypsum karst systems in arid zones, responsible for an

  19. Categorical Indicator Kriging for assessing the risk of groundwater nitrate pollution: the case of Vega de Granada aquifer (SE Spain).

    PubMed

    Chica-Olmo, Mario; Luque-Espinar, Juan Antonio; Rodriguez-Galiano, Victor; Pardo-Igúzquiza, Eulogio; Chica-Rivas, Lucía

    2014-02-01

    Groundwater nitrate pollution associated with agricultural activity is an important environmental problem in the management of this natural resource, as acknowledged by the European Water Framework Directive. Therefore, specific measures aimed to control the risk of water pollution by nitrates must be implemented to minimise its impact on the environment and potential risk to human health. The spatial probability distribution of nitrate contents exceeding a threshold or limit value, established within the quality standard, will be helpful to managers and decision-makers. A methodology based on non-parametric and non-linear methods of Indicator Kriging was used in the elaboration of a nitrate pollution categorical map for the aquifer of Vega de Granada (SE Spain). The map has been obtained from the local estimation of the probability that a nitrate content in an unsampled location belongs to one of the three categories established by the European Water Framework Directive: CL. 1 good quality [Min - 37.5 ppm], CL. 2 intermediate quality [37.5-50 ppm] and CL. 3 poor quality [50 ppm - Max]. The obtained results show that the areas exceeding nitrate concentrations of 50 ppm, poor quality waters, occupy more than 50% of the aquifer area. A great proportion of the area's municipalities are located in these poor quality water areas. The intermediate quality and good quality areas correspond to 21% and 28%, respectively, but with the highest population density. These results are coherent with the experimental data, which show an average nitrate concentration value of 72 ppm, significantly higher than the quality standard limit of 50 ppm. Consequently, the results suggest the importance of planning actions in order to control and monitor aquifer nitrate pollution. © 2013.

  20. Extreme storms during the last 6500 years from lagoonal sedimentary archives in the Mar Menor (SE Spain)

    NASA Astrophysics Data System (ADS)

    Dezileau, Laurent; Pérez-Ruzafa, Angel; Blanchemanche, Philippe; Degeai, Jean-Philippe; Raji, Otmane; Martinez, Philippe; Marcos, Concepcion; Von Grafenstein, Ulrich

    2016-06-01

    Storms and tsunamis, which may seriously endanger human society, are amongst the most devastating marine catastrophes that can occur in coastal areas. Many such events are known and have been reported for the Mediterranean, a region where high-frequency occurrences of these extreme events coincides with some of the most densely populated coastal areas in the world. In a sediment core from the Mar Menor (SE Spain), we discovered eight coarse-grained layers which document marine incursions during periods of intense storm activity or tsunami events. Based on radiocarbon dating, these extreme events occurred around 5250, 4000, 3600, 3010, 2300, 1350, 650, and 80 years cal BP. No comparable events have been observed during the 20th and 21st centuries. The results indicate little likelihood of a tsunami origin for these coarse-grained layers, although historical tsunami events are recorded in this region. These periods of surge events seem to coincide with the coldest periods in Europe during the late Holocene, suggesting a control by a climatic mechanism for periods of increased storm activity. Spectral analyses performed on the sand percentage revealed four major periodicities of 1228 ± 327, 732 ± 80, 562 ± 58, and 319 ± 16 years. Amongst the well-known proxies that have revealed a millennial-scale climate variability during the Holocene, the ice-rafted debris (IRD) indices in the North Atlantic developed by Bond et al. (1997, 2001) present a cyclicity of 1470 ± 500 years, which matches the 1228 ± 327-year periodicity evidenced in the Mar Menor, considering the respective uncertainties in the periodicities. Thus, an in-phase storm activity in the western Mediterranean is found with the coldest periods in Europe and with the North Atlantic thermohaline circulation. However, further investigations, such as additional coring and high-resolution coastal imagery, are needed to better constrain the main cause of these multiple events.

  1. An assessment of the influence of sulfidic mine wastes on rainwater quality in a semiarid climate (SE Spain)

    NASA Astrophysics Data System (ADS)

    Alcolea, A.; Fernández-López, C.; Vázquez, M.; Caparrós, A.; Ibarra, I.; García, C.; Zarroca, M.; Rodríguez, R.

    2015-04-01

    This study assessed the influence of the Sierra Minera de Cartagena - La Unión mining wastes on the surrounding areas, due to the sediment transport in the atmosphere. Monitoring of 15 weather stations located in the Campo de Cartagena land (SE Spain) was performed in the period December, 2004-March, 2008. A total of 920 rainfall water samples were collected and analyzed in this study. The network of weather stations covered a wide range of soil use and human activities (industrial, urban, agricultural, and mining sites). The physicochemical characterization involved determination of pH, EC, major ions, and the metals of interest in the soluble fraction of rainwater. Precipitations had an alkaline pH (7.0-7.9) and, compared to World Health Organization guidelines for drinking-water quality, samples were characterized by low EC (76-930 μS/cm), Ni (0.1-8 μg/L), Cu (3-88 μg/L), As (0.04-2 μg/L), Na+ (3-16 mg/L), K+ (0.41-30 mg/L), Ca2+ (6-51 mg/L), Mg2+ (up to 5 mg/L), Cl- (4-23 mg/L), NO3- (1-30 mg/L), and SO42- (4-35 mg/L) values. In certain locations, Zn, Cd, and Pb exceeded the guideline limits. A downward trend of H+, Zn, Cd, and Pb concentrations in total depositions was observed while the distance to the area affected by mining activities increased in the first 20 km. Rainwater quality was found to be just subtly affected by the metal-sulfide abandoned minesites, but without presenting a current threat to neither public health nor natural ecosystem. Nevertheless, greater attention should be paid in the future projections of climate change, where a significant increase in aridity may favor the atmospheric transport of pollutant particles.

  2. Do heavy metals existing in abandoned mining sites represent a real health risk? A study case in the SE Spain.

    NASA Astrophysics Data System (ADS)

    Martinez-Sanchez, Maria Jose; Perez-Sirvent, Carmen; García-Lorenzo, Mari Luz; Martínez-López, Salvadora; Perez-Espinosa, Victor; Hernández-Cordoba, Manuel; Bech, Jaime

    2013-04-01

    Mining activities have been carried out for centuries in Sierra Minera (SE Spain) giving rise to a large number of sites distributed throughout the zone in which residues are accumulated. This communication reports studies as regards metal mobilization and analysis of the health risk that could be posed by inhalation, dermic contact or occasional ingestion of this type of sediments. Lead was used as the metal for the studies due to its particular abundance in the zone. A large number of samples were taken and general analytical determinations (pH, particle size, organic matter, equivalent calcium carbonate content and mineralogical composition) were carried out in order its characterization. An in vitro method for obtaining formation on Pb bioaccessibility in these mine waste materials was also carried out. Our results prove that mineral associations, different alteration states and sorption/desorption processes play an important role in the bioavailability of lead. In addition, it is noteworthy that the metal fraction dissolved by the proposed in vitro methodology is lower than 100%, both in the stomach and intestinal phases. Finally an assessment of the risk posed by lead is achieved. To this respect it should be noted that the IRIS database provide cancer slope factor and reference dose, as a way to assess the risk caused by arsenic, cadmium and copper but no for lead, probably due to the wide variety of real situations, and the discrepancy of the sources. The way here suggested is a novelty in this sense, and the results could be extrapolated to other similar zones and be incorporated to the general protocol of risk assessment applied to contaminated sites.

  3. Total organic carbon and humus fractions in restored soils from limestone quarries in semiarid climate, SE Spain

    NASA Astrophysics Data System (ADS)

    Luna Ramos, Lourdes; Miralles Mellado, Isabel; Ángel Domene Ruiz, Miguel; Solé Benet, Albert

    2016-04-01

    Mining activities generate erosion and loss of plant cover and soil organic matter (SOM), especially in arid and semiarid Mediterranean regions. A precondition for ecosystem restoration in such highly disturbed areas is the development of functional soils with sufficient organic matter. But the SOM quality is also important to long-term C stabilization. The resistance to biodegradation of recalcitrant organic matter fractions has been reported to depend on some intrinsic structural factors of humic acid substances and formation of amorphous organo-mineral recalcitrant complexes. In an experimental soil restoration in limestone quarries in the Sierra de Gádor (Almería), SE Spain, several combinations of organic amendments (sewage sludge and compost from domestic organic waste) and mulches (gravel and woodchip) were added in experimental plots using a factorial design. In each plot, 75 native plants (Anthyllis cytisoides, A. terniflora and Macrochloa tenacissima) were planted and five years after the start of the experiment total organic carbon (TOC), physico-chemical soil properties and organic C fractions (particulate organic matter, H3PO4-fulvic fraction, fulvic acids (FA), humic acids (HA) and humin) were analyzed. We observed significant differences between treatments related to the TOC content and the HA/FA ratio. Compost amendments increased the TOC, HA content and HA/FA ratio, even higher than in natural undisturbed soils, indicating an effective clay humus-complex pointing to progressively increasing organic matter quality. Soils with sewage sludge showed the lowest TOC and HA/FA ratio and accumulated a lower HA proportion indicating poorer organic matter quality and comparatively lower resilience than in natural soils and soils amended with compost.

  4. Geochemical background of zinc, cadmium and mercury in anthropically influenced soils in a semi-arid zone (SE, Spain)

    NASA Astrophysics Data System (ADS)

    García-Lorenzo, M. L.; Pérez-Sirvent, C.; Martínez-Sánchez, M. J.; Molina, J.; Tudela, M. L.; Hernández-Córdoba, M.

    2009-04-01

    This work seeks to establish the geochemical background for three potentially toxic trace elements (Zn, Cd and Hg) in a pilot zone included in the DesertNet project in the province of Murcia. The studied area, known as Campo de Cartagena, Murcia (SE Spain) is an area of intensive agriculture and has been much affected over the years by anthropic activity. The zone can be considered an experimental pilot zone for establishing background levels in agricultural soils. Sixty four samples were collected and corresponded to areas subjected to high and similar agricultural activity or soils with natural vegetation, which correspond to abandoned agricultural areas. The Zn content was determined by flame atomic absorption spectrometry. The Cd content was determined by electrothermal atomization atomic absorption spectrometry and mercury content was determined by atomic fluorescence spectrometry. Geostatistical analysis consisting of kriging and mapping was performed using the geostatistical analyst extension of ArcGIS 8.3. Zinc values ranged from 10 mg kg-1 to 151 mg kg-1, with an average value of 45 mg kg-1. Cadmium values ranged between 0.1 mg kg-1 and 0.9mg kg-1, with a mean value of 0.3 mg kg-1 and mercury values ranged from 0.1 mg kg-1 to 2.3 mg kg-1, with a mean value of 0.5 mg kg-1. At a national level, the Spanish Royal Decree 9/2005 proposes toxicological and statistical approaches to establish background values. According to the statistical approach, background values consist of the median value for the selected element. The background values for Zn, Cd and Hg in the studied area were 40 mg kg-1 for Zn, 0.3 mg kg-1 for Cd and 0.4 mg kg-1 for Hg.

  5. Thinning effects on litterfall remaining after 8 years and improved stand resilience in Aleppo pine afforestation (SE Spain).

    PubMed

    Jiménez, M N; Navarro, F B

    2016-03-15

    Monthly litterfall was monitored over a 3-year period in afforested Aleppo pines in the Mediterranean semiarid SE Spain with the aim of determining the long-term response of pines to reductions in tree competition and how this forest practice might influence stand resilience. Three thinning intensities applied 5 years earlier were evaluated (T75 = 75% of the basal area removed, T60 = 60% and T48 = 48%), both at the stand and at the tree level. On average, the total annual litterfall varied between 1.30 Mg ha(-1) yr(-1) (±0.24 SE) in T75 and 3.28 Mg ha(-1) yr(-1) (±0.78 SE) in the unthinned control. At the stand level, monthly differences among the treatments were found over time in the needles (F = 11.09, df = 3, P = 0.0009) and woody fraction (F = 4.36, df = 3, P = 0.0269) following the thinning gradient: T0 (control)>T48 > T60 > T75, and for the total amount of needles (χ(2) = 9.33, P = 0.025) and twigs (χ(2) = 9.11, P = 0.027) recorded at the end of the study period. High amounts of twig and needle fall were recorded during summer and beginning of autumn, whereas the main miscellanea inputs were registered during the spring, coinciding with the fall of nests and frass from caterpillar outbreaks. At the tree level, the total litterfall fluctuated between 1.5 kg tree yr(-1) in T0 (2nd yr) and 7.0 kg tree yr(-1) in T75 (3rd yr), although mean annual statistical differences among the treatments were found only for the first year of monitoring. However, needle fall was higher for larger pines (T75) than for the smaller ones in control (T0) when the data were analysed over the 3-year-period (F = 3.64, df = 3, P = 0.0247), and the same happened for the woody fraction (F = 3.63, df = 3, P = 0.0250). By contrast, pine trees in the unthinned control registered needle-fall rates (measured as kg m(-2) tree(-1)) that were similar to or higher than those of pine trees in thinned stands, suggesting that defoliation

  6. Transplant experiments to examine the habitat exclusivity of lichen dominated soil crust communities in the El Cautivo badlands, SE Spain

    NASA Astrophysics Data System (ADS)

    Bevan, J.; Alexander, R.; Lazaro-Suau, R.

    2012-04-01

    Successive episodes of erosion into late Miocene marls have produced the complex, deeply incised topography of the El Cautivo badlands in Almería, SE Spain. Phanerogamic vegetation is sparse in this extreme semi-arid environment and biological soil crusts constitute the predominant cover on all surfaces except those with active erosion. The soil crusts comprise a diverse range of lichen-dominated communities, which previous work (Bevan, 2008) has indicated can be separated into four main types, each characterised by one or a small number of lichen species. Distribution patterns of these main crust types appear to reflect (micro)topographic and microclimatic variability at the site with each community type occupying a specific habitat. The main crust types are identified as BC, a brown crust typically containing Endocarpon pusillum, Collema spp, Fulgensia spp and Placynthium nigrum, and DC, SC, LC, three white crusts characterised respectively by Diploschistes diacapsis, Squamarina lentigera and Lepraria crassissima. Previous work at the site (Bevan, 2008) has revealed associations between the distribution of these four crust types and a number of microclimatic variables, in particular insolation and temperature. BC tends to occur in the most exposed parts of the site where insolation and surface temperatures reach their highest levels and humidity and soil moisture tends to be low. LC appears more restricted to shaded sites with lower insolation and temperature and higher humidity and soil moisture. DC and SC occupy intermediate ranges of these variables. In order to test the degree to which the apparent habitat preferences of the crust types are obligatory or preferential a series of transplant experiments were devised. Replicate samples representative of each of the four crust types were reciprocally transplanted into areas dominated by each of the other types and also into an area previously eroded and bare. Each location had the following groups of plots: a

  7. Effect of partial melting on Vp and Vs in crustal enclaves from Mazarrón (SE Spain)

    NASA Astrophysics Data System (ADS)

    Ferri, Fabio; Burlini, Luigi; Cesare, Bernardo

    2016-03-01

    The combination of compressional and shear wave velocity is an important tool in discriminating rock types and identifying residing melts within the continental crust. Here we report the laboratory measurements for Vp and Vs obtained in varying conditions up to those exceeding the beginning of melting (950 °C at 500 MPa confining pressure) on two residual garnet-biotite-sillimanite-cordierite-spinel metapelitic enclaves recovered from the Neogene dacites of Mazarrón (SE Spain). The enclaves preserve widespread interstitial rhyolitic glass as evidence of primary melt extraction. At 500 MPa, the experimental Vp ranges from 7.21 ÷ 7.46 km s- 1 at room temperature to 5.44 km/s at 950 °C. The mean Vs is 4.5 km/s at room temperature with shear-wave splitting of 0.25 ÷ 0.3 km/s, measured along three mutually orthogonal directions. When temperature increases, the Vs evidences a reversible slope change at about 650 °C, and the shear-wave splitting reduces to zero (isotropic material) at 850-950 °C, where the sample Vs is ~ 3.0 km/s. The Vp anisotropy is 7-10% up to 700 °C increasing to ~ 20% at 950 °C, while the Vs anisotropy continuously decreases with temperature from 5% to 7% at room temperature to zero at 950 °C. No mineral reactions are observed up to 650-700 °C; however, microstructure equilibrates due to the relaxation of the primary glass at the glass transition temperature. Between 850 °C and 950 °C, a new melting reaction is observed producing biotite + spinel + ilmenite + plagioclase + melt. At melting, the rock becomes isotropic for Vs, and Poisson's ratio increases to 0.30. Our seismic data show that the seismic signature of high grade metapelitic rocks is similar to that of mafic materials. The evolution of Vp and Vs at melting conditions is compatible with the geophysical data of the area, supporting the hypothesis of the current existence of anatectic melts at intermediate depths of the Alborán domain.

  8. Testing models for the Messinian salinity crisis: The Messinian record in Almería, SE Spain

    NASA Astrophysics Data System (ADS)

    Braga, Juan C.; Martín, José M.; Riding, Robert; Aguirre, Julio; Sánchez-Almazo, Isabel M.; Dinarès-Turell, Jaume

    2006-06-01

    Neogene intermontane basins in Almería Province, SE Spain, display excellent exposures of Messinian (Late Miocene) sequences. The Sorbas, Almería-Níjar and Vera basins maintained connection with the Mediterranean throughout the Messinian, except during the major desiccation phase leading to the formation of salt in the deep centre of the Western Mediterranean. These basins were part of the Western Mediterranean with no separate link to the Atlantic Ocean. The presence of normal marine sediments in these basins reflects the Western Mediterranean watermass. Messinian pre-evaporitic sediments in the basins of southeastern Almería do not show gradual change towards evaporite deposits. Instead they contain stenohaline invertebrates right up to a major erosion surface that separates them from overlying gypsum deposits. This contradicts suggestion of progressive salinity increase in this part of the Western Mediterranean prior to the Messinian Salinity Crisis (MSC); it also indicates that initiation of evaporite precipitation was not synchronous throughout the Mediterranean Basin. There is no major erosion surface within or at the top of the evaporites in these Almería basins, and the gypsum beds exhibit upward transition to siliciclastic and carbonate deposits. This is inconsistent with a model of Messinian Mediterranean evaporite formation whereby deposition of marginal evaporites was followed by their erosion during drawdown that resulted in formation of evaporites in the centre of the Western Mediterranean. The presence of stenohaline biotas in siliciclastic deposits interbedded with the gypsum and in the Messinian post-evaporitic sediments, challenges the view that a long-standing large body of brackish water (the Lago Mare) filled the Western Mediterranean following the MSC and prior to Early Pliocene flooding. It also contradicts the concept of many relatively small brackish basins spread across an otherwise desiccated Western Mediterranean basin. The basins

  9. How land degradation affects the carbon balance and its component processes: case of study in SE Spain

    NASA Astrophysics Data System (ADS)

    López Ballesteros, Ana; Oyonarte, Cecilio; Kowalski, Andrew S.; Serrano-Ortiz, Penélope; Sánchez-Cañete, Enrique P.; Rosario Moya, M.; Domingo, Francisco

    2017-04-01

    The concept of land degradation stems from the loss of an ecosystem's biological productivity, which in turn relies on several degradation processes such as long-term loss of natural vegetation, depletion of soil nutrients, soil compaction or water and wind erosion. In this context, desertification means land degradation in arid, semi-arid and dry sub-humid areas due to climatic and/or human factors. Currently, drylands occupy more than one third of the global terrestrial surface and will probably expand under future climate change scenarios. Drylands' key role in the global C balance has been demonstrated, but the effects of desertification and/or climate change on C sequestration by these ecosystems needs further research. In the present study, we compare net carbon exchange between two experimental sites representing a "degraded" and "non-degraded" grazed semiarid grasslands, separated by ˜15 km in SE Spain, via eddy covariance measurements over 6 years, with high variability in precipitation magnitude and distribution. Results show a striking difference in the annual C balances with average emissions of 196 ± 40 and -23 ± 20 g C m-2 yr-1 for the "degraded" and "non-degraded" sites, respectively. At the seasonal scale, differing patterns in net CO2 fluxes were detected over both growing and dry seasons. As expected, larger net C uptake over longer periods was observed in the "non-degraded" site, however, much greater net C release was measured in the "degraded" site over drought period. We tested differences in all monitored meteorological, ambient and subsoil variables and found most relevant that CO2 at 1.50 m belowground was around 1000 ppm higher in the "degraded" site. Thus, we believe that subterranean ventilation of this vadose zone CO2, observed at both sites, largely drives the differences in C dynamics between them. Overall, the 12 site-years of data allow direct exploration of the roles of climate and land degradation in the biological and non

  10. Interannual variability of Net Ecosystem CO2 Exchange and its component fluxes in a subalpine Mediterranean ecosystem (SE Spain)

    NASA Astrophysics Data System (ADS)

    Chamizo, Sonia; Serrano-Ortiz, Penélope; Sánchez-Cañete, Enrique P.; Domingo, Francisco; Arnau-Rosalén, Eva; Oyonarte, Cecilio; Pérez-Priego, Óscar; López-Ballesteros, Ana; Kowalski, Andrew S.

    2015-04-01

    Recent decades under climate change have seen increasing interest in quantifying the carbon (C) balance of different terrestrial ecosystems, and their behavior as sources or sinks of C. Both CO2 exchange between terrestrial ecosystems and the atmosphere and identification of its drivers are key to understanding land-surface feedbacks to climate change. The eddy covariance (EC) technique allows measurements of net ecosystem C exchange (NEE) from short to long time scales. In addition, flux partitioning models can extract the components of net CO2 fluxes, including both biological processes of photosynthesis or gross primary production (GPP) and respiration (Reco), and also abiotic drivers like subsoil CO2 ventilation (VE), which is of particular relevance in semiarid environments. The importance of abiotic processes together with the strong interannual variability of precipitation, which strongly affects CO2 fluxes, complicates the accurate characterization of the C balance in semiarid landscapes. In this study, we examine 10 years of interannual variability of NEE and its components at a subalpine karstic plateau, El Llano de los Juanes, in the Sierra de Gádor (Almería, SE Spain). Results show annual NEE ranging from 55 g C m-2 (net emission) to -54 g C m-2 (net uptake). Among C flux components, GPP was the greatest contributing 42-57% of summed component magnitudes, while contributions by Reco and VE ranged from 27 to 46% and from 3 to 18%, respectively. Annual precipitation during the studied period exhibited high interannual variability, ranging from 210 mm to 1374 mm. Annual precipitation explained 50% of the variance in Reco, 59% of that in GPP, and 56% for VE. While Reco and GPP were positively correlated with annual precipitation (correlation coefficient, R, of 0.71 and 0.77, respectively), VE showed negative correlation with this driver (R = -0.74). During the driest year (2004-2005), annual GPP and Reco reached their lowest values, while contribution of

  11. Geodetic slip rate estimates for the Alhama de Murcia and Carboneras faults in the SE Betics, Spain

    NASA Astrophysics Data System (ADS)

    Khazaradze, Giorgi; Echeverria, Anna; Masana, Eulàlia

    2016-04-01

    The Alhama de Murcia and the Carboneras faults are the most prominent geologic structures within the Eastern Betic Shear Zone (EBSZ), located in SE Spain. Using continuous and campaign GPS observations conducted during the last decade, we were able to confirm the continuing tectonic activity of these faults by quantifying their geodetic slip-rates and comparing the estimated values with the geological (including paleoseismological) observations. We find that the bulk of the observed deformation is concentrated around the Alhama de Murcia (AMF) and the Palomares (PF) faults. The geodetic horizontal slip rate (reverse-sinistral) of 1.5±0.3 mm/yr calculated for the AMF and PF fault system is in good agreement with geological observations at the AMF, as well as, the focal mechanism of the 2011 Lorca earthquake, suggesting a main role of the AMF. We also find that the geodetic slip rate of the Carboneras fault zone (CFZ) is almost purely sinistral strike-slip with a rate of 1.3±0.2 mm/yr along N48° direction, very similar to 1.1 mm/yr geologic slip-rate, estimated from recent onshore and offshore paleoseismic and geomorphologic studies. The fact the geodetic and the geologic slip-rates are similar at the AMF and CF faults, suggests that both faults have been tectonically active since Quaternary, slipping at approximately at constant rate of 1.1 to 1.8 mm/yr. Since the existing GPS data cannot discern whether the CFZ is slipping seismically or aseismically, we have intended to relate the on-going seismic activity to the slip-rates estimated using GPS. For this reason we compared seismic and geodetic strain rates, where the latter are larger than seismic strain rates, suggesting the presence of aseismic processes in the area. Nevertheless, due to the large earthquake recurrence intervals, we may be underestimating the seismic strain rates. The direction of the P and T average stress axes are in good agreement with geodetic principal strain rate axes. To summarize, in

  12. Lichenometry dating of rock collapse related to the great Lisbon Earthquake (1755) at the SE part of Spain

    NASA Astrophysics Data System (ADS)

    Perez-Lopez, Raul; Rodriguez-Pascua, Miguel Angel; Silva, Pablo G.; Bischoff, James L.; Owen, Lewis A.; Giner-Robles, Jorge L.; Díez-Herrero, Andres

    2010-05-01

    "De una montaña, se desprendió una parte" (A large part of a mountain has fallen down). This sentence was extracted from an ancient text written at the end of the 18th Century, in relation with the great Earthquake of Lisbon in 1755 (Martínez-Solares, 2001), and describing the rock collapse recorded near the small town of Agramón, 50 km southeastward of Albacete city (SE of Spain). Up to now, archaeologists have suggested this rock collapse to the archaeological site of "El Tolmo de Minateda", a small butte (420 m long) of calcarenitic sandstone bedrock with a flat top and scarped cliffs (20m high) bordering the butte. This ancient city was habited by several civilizations from Bronze Ages to modern times (i.e. Iberians, Roman, Visigoths, Muslims, Medieval ages, etc.). The landscape of this area is characterized by a flat terrain with isolated relict structural buttes consisting of Late Neogene marine sandstones created by differential erosion. The site exhibits three different stages of massive rock collapse. The oldest is located at the north of the site while the younger is located at the south part of the site and affecting Visigothic stone carved tombs. Archaeologists have postulated that the youngest of these was triggered by the Lisbon earthquake of 1755. We have carried out a lichenometric analysis over the free-faces of the rock blocks, with the aim of testing the postulate. For our purpose, we have calculated the calibrated growth curve for Aspicilia Radiosa (Hoff.), which yields a linear growth of 0.2425 mm per yr (R2 = 0.97, N=20). This growth rate was determined for the time interval from 800 BP yrs to the present by two different approaches: (1) rates obtained from cemetery measurements (200 yrs BP) and (2) rates determined from well-dated archaeological monuments (200-800 yrs BP). Our analysis revealed that the age of the rock-falling was in the year 1754 AD ±4. Thus, our results confirm that this collapse of ca. 5000 m3 of volume was triggered

  13. Slab flattening driving regional uplift in the Cordilleras Blanca and Negra, Western Andes

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The Andean range topographic evolution is known to have had a strong impact on regional climate by building an orographic barrier that preserved its western flank from the south Atlantic moisture. Even if largely invoked, the impact of subduction processes on the uplift and relief building is not yet well understood in the Andes. The northern Peru is characterized by a present day flat subduction zone (3-15°S), where both the geometry and temporal evolution of the flat-slab are well constrained. The subduction of two buoyant anomalies, the Nazca ridge and the lost Inca plateau controlled the slab flattening. The highest Peruvian peaks in the Cordillera Blanca (6768 m), and the Cordillera Negra (5187 m) are located just above the flat-slab segment. Both ranges trend parallel to the subduction zone and are separated by the NW-SE Rio Santa valley. The Cordillera Blanca batholith emplaced at 8-5 Ma and renders of an abnormal magmatic activity over a planar subduction. This area is a perfect target to explore the impact of slab flattening on the topography and uplift in the Occidental Cordillera of the Andes. We present new AHe and AFT data from three vertical profiles located in both the Cordilleras Blanca and Negra. We compare time-temperature paths obtained from inverse modeling of the thermochronological data with the timing of the slab flattening, the arrival of the Nazca ridge and magmatism. Our thermochronological data evidences a regional exhumation in the Occidental Cordillera from ~10 Ma. We propose that the Nazca ridge subduction below the Occidental Cordillera (11 Ma) and slab flattening (8 Ma) drive the Occidental Cordillera uplift and thus exhumation. We evidence the important contribution of the magmatism in the Cordillera Blanca exhumation and high relief building in the Occidental Cordillera. Our new thermochronological data highlight the control of both the subduction processes and magmatism on the paleogeography and uplift in the Andes. Finally, the

  14. Constraining controls on carbonate sequences with high-resolution chronostratigraphy: Upper Miocene, Cabo de Gata region, SE Spain

    USGS Publications Warehouse

    Montgomery, P.; Farr, M.R.; Franseen, E.K.; Goldstein, R.H.

    2001-01-01

    A high-resolution chronostratigraphy has been developed for Miocene shallow-water carbonate strata in the Cabo de Gata region of SE Spain for evaluation of local, regional and global factors that controlled platform architecture prior to and during the Messinian salinity crisis. Paleomagnetic data were collected from strata at three localities. Mean natural remanent magnetization (NRM) ranges between 1.53 ?? 10-8 and 5.2 ?? 10-3 Am2/kg. Incremental thermal and alternating field demagnetization isolated the characteristic remanent magnetization (ChRM). Rock magnetic studies show that the dominant magnetic mineral is magnetite, but mixtures of magnetite and hematite occur. A composite chronostratigraphy was derived from five stratigraphic sections. Regional stratigraphic data, biostratigraphic data, and an 40Ar/39Ar date of 8.5 ?? 0.1 Ma, for an interbedded volcanic flow, place the strata in geomagnetic polarity Chrons C4r to C3r. Sequence-stratigraphic and diagenetic evidence indicate a major unconformity at the base of depositional sequence (DS)3 that contains a prograding reef complex, suggesting that approximately 250 000 yr of record (Subchrons C3Br.2r to 3Br.1r) are missing near the Messinian-Tortonian boundary. Correlation to the GPTS shows that the studied strata represent five third- to fourth-order DSs. Basal units are temperate to subtropical ramps (DS1A, DS1B, DS2); these are overlain by subtropical to tropical reefal platforms (DS3), which are capped by subtropical to tropical cyclic carbonates (Terminal Carbonate Complex, TCC). Correlation of the Cabo de Gata record to the Melilla area of Morocco, and the Sorbas basin of Spain indicate that early - Late Tortonian ramp strata from these areas are partially time-equivalent. Similar strata are extensively developed in the Western Mediterranean and likely were influenced by a cool climate or influx of nutrients during an overall rise in global sea-level. After ramp deposition, a sequence boundary (SB3) in

  15. Electrical conductivity in a partially molten lower crust from laboratory measurements on xenoliths (El Hoyazo, SE Spain)

    NASA Astrophysics Data System (ADS)

    Ferri, F.; Gibért, B.; Violay, M.; Schilling, F. R.; Cesare, B.

    2009-04-01

    The presence of High Conductive Zones (HCZs) within the lower crust is explained by several mechanisms involving phases as graphite, brines and partial melts, which enhance the conductivity when inteconnected over large distances. In the Internal Betics (Southern Spain) the anomalous HCZ imaged at the bottom of a thinned lower crust (Pous et al., 1999) is combined with low seismic velocities and high heat flow values (Carbonell et al., 1998) supporting the hypothesis that partial melts are present at depths. This is further confirmed by the recovery of restitic lower crustal xenoliths retaining evidence of partial melting (Zeck, 1968). The xenolith also contain up to 2 wt% of graphite which may contribute to the conductivity enhancement. The present study is focused on the electrical conductivity at high pressure and temperature of four garnet-biotite-sillimanite metapelitic xenoliths collected from the Neogene dacites of El Hoyazo (SE Spain). The paragenesis is represented by garnet + biotite + sillimanite + plagioclase ± cordierite coexisting with graphite and widespread rhyolitic melt as inclusions and interstitial glass (~10 wt%) (Cesare & Gómez-Pugnaire, 2001). The assemblage developed during regional anatexis at 850-900°C and 500 - 700 MPa (Cesare et al., 1997) and melt was frozen-in during fast uplift. In order to discriminate the contibution of graphite and melt, assess the effect of their geometrical distribution and infer the influence of the glass rheology to the electrical conductivity, experiments were performed in two gas apparata at sealed and unsealed conditions. In unsealed runs, in fact, the porosity remains open which prevents graphite reconnection. The sealed experiments were conducted in a Paterson Apparatus up to 680°C and 840°C at 100 MPa and to 900°C at 300 MPa, the unsealed ones in an internally heated gas apparatus (IHPV) with Ar as pressure medium up to 950°C and 400 MPa. For each sample three mutually orthogonal cores (X, Y, Z

  16. Quantitative controls on location and architecture of carbonate depositional sequences: Upper miocene, cabo de gata region, SE Spain

    USGS Publications Warehouse

    Franseen, E.K.; Goldstein, R.H.; Farr, M.R.

    1997-01-01

    Sequence stratigraphy, pinning-point relative sea-level curves, and magnetostratigraphy provide the quantitative data necessary to understand how rates of sea-level change and different substrate paleoslopes are dominant controls on accumulation rate, carbonate depositional sequence location, and internal architecture. Five third-order (1-10 my) and fourth-order (0.1-1.0 my) upper Miocene carbonate depositional sequences (DS1A, DS1B, DS2, DS3, TCC) formed with superimposed higher-frequency sea-level cycles in an archipelago setting in SE Spain. Overall, our study indicates when areas of high substrate slope (> 15??) are in shallow water, independent of climate, the location and internal architecture of carbonate deposits are not directly linked to sea-level position but, instead, are controlled by location of gently sloping substrates and processes of bypass. In contrast, if carbonate sediments are generated where substrates of low slope ( 15.6 cm/ky to ??? 2 cm/ky and overall relative sea level rose at rates of 17-21.4 cm/ky. Higher frequency sea-level rates were about 111 to more than 260 cm/ky, producing onlapping, fining- (deepening-) upward cycles. Decreasing accumulation rates resulted from decreasing surface area for shallow-water sediment production, drowning of shallow-water substrates, and complex sediment dispersal related to the archipelago setting. Typical systems tract and parasequence development should not be expected in "bypass ramp" settings; facies of onlapping strata do not track base level and are likely to be significantly different compared to onlapping strata associated with coastal onlap. Basal and upper DS2 reef megabreccias (indicating the transition from cool to warmer climatic conditions) were eroded from steep upslope positions and redeposited downslope onto areas of gentle substrate during rapid sea-level falls (> 22.7 cm/ky) of short duration. Such rapid sea-level falls and presence of steep slopes are not conducive to formation of

  17. Quantitative controls on location and architecture of carbonate depositional sequences: upper miocene, cabo de gata region, se Spain

    USGS Publications Warehouse

    Franseen, E.K.; Goldstein, R.H.; Farr, M.R.

    1998-01-01

    Sequence stratigraphy, pinning-point relative sea-level curves, and magnetostratigraphy provide the quantitative data necessary to understand how rates of sea-level change and different substrate paleoslopes are dominant controls on accumulation rate, carbonate depositional sequence location, and internal architecture. Five third-order (1-10 my) and fourth-order (0.1-1.0 my) upper Miocene carbonate depositional sequences (DS1A, DS1B, DS2, DS3, TCC) formed with superimposed higher-frequency sea-level cycles in an archipelago setting in SE Spain. Overall, our study indicates when areas of high substrate slope (> 15??) are in shallow water, independent of climate, the location and internal architecture of carbonate deposits are not directly linked to sea-level position but, instead, are controlled by location of gently sloping substrates and processes of bypass. In contrast, if carbonate sediments are generated where substrates of low slope ( 15.6 cm/ky to ??? 2 cm/ky and overall relative sea level rose at rates of 17-21.4 cm/ky. Higher frequency sea-level rates were about 111 to more than 260 cm/ky, producing onlapping, fining- (deepening-) upward cycles. Decreasing accumulation rates resulted from decreasing surface area for shallow-water sediment production, drowning of shallow-water substrates, and complex sediment dispersal related to the archipelago setting. Typical systems tract and parasequence development should not be expected in "bypass ramp" settings; facies of onlapping strata do not track base level and are likely to be significantly different compared to onlapping strata associated with coastal onlap. Basal and upper DS2 reef megabreccias (indicating the transition from cool to warmer climatic conditions) were eroded from steep upslope positions and redeposited downslope onto areas of gentle substrate during rapid sea-level falls (> 22.7 cm/ky) of short duration. Such rapid sea-level falls and presence of steep slopes are not conducive to formation of

  18. Spectral detection of different types of soil crusts under intact and disturbance conditions in semiarid environments from SE Spain.

    NASA Astrophysics Data System (ADS)

    Chamizo, S.; Stevens, A.; Cantón, Y.; Domingo, F.; van Wesemael, B.

    2009-04-01

    Biological Soil Crusts (BSCs) consist of an association of soil particles with cyanobacteria, algae, microfungi, liverworts, bryophytes and lichens creating a cohesive thin horizontal layer on the soil surface. They have a widespread distribution in arid and semiarid regions, which comprise over 40% of the world's land surface. BSCs play an important role on hydrological and ecological functioning of arid and semiarid ecosystems since they influence all components of hydrological balance (runoff, rainfall capture, infiltration, evaporation, water retention capacity) and erosion. It is well known that BSCs at local scale reduce water erosion by protecting soil against raindrop impact. However, their effects have to be evaluated at different spatial scales, because in many cases BSCs lead to an increase of runoff and downslope erosion or water harvesting from crusted areas to nourish adjacent vegetated areas. Moreover, BSCs are easily damaged by livestock or human activities and the disturbance usually has great significance for the coverage and the composition of the community of the BSCs, the developmental stage of the BSC and their effects on hydrology and erosion. So, to accurately predict runoff and erosion processes, the spatial distribution of soil crust types and their disturbance conditions should be included in models. To map soil crusting at large scales, the use of their spectral characteristics can be a useful method. The objectives of this work are i) to analyze the spectral characteristics of different crust types (physical and biological soil crusts), also corresponding to different crust development stages, in two semiarid areas in SE Spain, El Cautivo (in the Tabernas Desert) and Amoladeras (in the Natural Park Cabo de Gata-Níjar), ii) to demonstrate the efficiency of diffuse reflectance spectroscopy, especially in the visible part of the spectrum, for classifying different crust types and different crust disturbance conditions. Spectral

  19. Lower Aptian Sequence at Madoz (SE Spain) in Relation to Cretaceous Anoxic Event-1a (OAE- 1a)

    NASA Astrophysics Data System (ADS)

    Gaona-Narvaez, T.; Maurrasse, F. J.; Lamolda, M. A.

    2008-05-01

    The Aptian stage at Madoz in the Sierra de Aralar, NE Spain, shows contrasting lithological succession of intercalated clastic-rich intervals and rudist-rich limestone beds varying between Medium Olive Gray (5Y 5/1) and Olive Gray (5Y 4/1). They are subdivided into different sub-units (Duvernois et al., 1972; Cherchi & Schroeder, 1998) with unit 1, as well as subunits 2a and 2b of "Madoz Limestone" are placed within the Lower Aptian Palorbitolina lenticularis Zone. Their stratigraphic level corresponds at least to the Deshayesites deshayesi ammonite zone, based on the presence of the nominate taxon in clastic Unit 1. Sub-unit 2b includes a distinct 180-cm thick black (Medium to Dark Gray, -N4 to N3) shale layer toward the close of the upper Lower Aptian. Detailed microfacies analysis was carried out on the Lower Aptian interval in order to characterize the different lithofacies and their possible relationship to Cretaceous OAE-1a. Subunit 2a is 20m thick and its microfacies consists of sparse and packed biomicrites, moderate to poorly sorted fine calcirudites and calcarenites composed of 40 - 50% remains of corals, predominantly non-rudist bivalves, echinoids, bryozoans, benthic foraminifera and calcareous algae indicative of well oxygenated conditions. Matrix and bioclasts are highly affected by neomorphism and growing of micritic envelopes is frequent. Superjacent subunit 2b is also 20m thick, but is lithologically very variable and consists of interbeds of indurated biomicrite with 30 - 50 % fossil fragments dominated by orbitolinids, and echinoids, non-rudist bivalves, benthic foraminifers, and algae as secondary components. These beds also contain 15 - 25 % mostly silt-size quartz grains, and clays. Other indurated biomicrite beds within subunit 2b contain 1 - 20 % fragments of non-rudist bivalves, echinoids, other benthic foraminifers, and algae, but orbitolinids are scarce. Terrigenous components make up 10 - 25 % of the matrix. Subunit 2b also includes soft

  20. Orogenesis at the southern tip of the Americas: the structural evolution of the Cordillera Darwin metamorphic complex, southernmost Chile

    NASA Astrophysics Data System (ADS)

    Cunningham, W. Dickson

    1995-04-01

    New, detailed lithologic and structural data are presented from three separately mapped areas along the southern boundary of the Cordillera Darwin metamorphic complex of southernmost Chile. Cordillera Darwin is a unique uplift because it exposes the highest grade rocks in the Andes south of Peru and averages 1 km higher in elevation than adjacent areas. The structural data indicate that Cordillera Darwin experienced mid-Late Cretaceous trans-pressional deformation with a partitioned strike-slip component localized along the Beagle Channel that forms the southern boundary to the range. Foliation, lineation and fold axis trends indicate NE-SW-directed contraction and NW-SE strike-slip shearing (present directions) during progressive {D1}/{D2} Andean deformation. D2 deformation is marked by outcrop-to 10 km-scale south-southwest-vergent folds. Late Cretaceous-Tertiary brittle-ductile and brittle left-lateral strike-slip faults and shear zones crosscut all {D1}/{D2} structures. Although limited structural evidence for extensional tectonics was documented in this study, apparent normal offsets across both arms of the Beagle Channel and previously documented field evidence for extension from other areas in Cordillera Darwin suggest that transtensional displacements also may have occurred in southern Cordillera Darwin during the Late Cretaceous-Early Tertiary. Cordillera Darwin's position within the evolving Patagonian Orocline adjacent to an evolving Mesozoic-Cenozoic left-lateral transform boundary between the South American and Antarctic plates, and later the South American and Scotia plates, necessitates consideration of the possible effects of regional counterclockwise rotation on development of structures. Regional counterclockwise rotation of Cordillera Darwin may have controlled the temporal and spatial transition of deformational regimes within Cordillera Darwin. Exhumation of the metamorphic core of Cordillera Darwin during the Late Cretaceous-Early Tertiary is

  1. Two-dimensional P-T-t modelling and the dynamics of extension and inversion in the Betic Zone (SE Spain)

    NASA Astrophysics Data System (ADS)

    van Wees, J. D.; De Jong, K.; Cloetingh, S.

    1992-03-01

    The Internal Zone of the Betic Cordilleras offers a unique opportunity to study the dynamics of lithospheric processes at mid crustal levels, which controlled the formation and evolution of the southeastern margin of Iberia. In this paper we present the result of two-dimensional numerical modelling of P-T-t paths related to latest Oligocene and Early Miocene extension and inversion in the Betic Zone. The ages of P-T-t loops are constrained by an extensive data set of geothermo-barometric and geochronological data, including 40Ar/ 39Ar laser probe data. We investigate the thermo-mechanical evolution of the Betic Zone using numerical models for simple shear, pure shear and combined shear. The Wernicke simple shear model fails to explain the observed temperatures in excess of 500°C and is not consistent with the occurrence of intrusions of ultramafic rocks in the western Betics. However, the delaminated simple shear model with low-angle faults located only at lower crustal levels, is found to be consistent with the P-T-t data. After a heating phase, associated with a finite extension of 80 km, rapid cooling occurred reflecting inversion of the extensional structure by NW-SE to N-S directed compression. Palaeo-rheological models for the latest Oligocene-Early Miocene times demonstrate the important role of the detachments produced during crustal extension for the dynamics of the subsequent inversion phase. The modelling strongly suggest that inversion locked after 60 km of finite convergence. After locking of the inversion, overthrusting in a northward direction occurred, which is compensated by pure shear deformation in the lower crust in the southeastern part of the Betic Zone.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  4. Influence of an intensive agricultural drainage basin on the seasonal distribution of organic pollutants in seawater from a Mediterranean coastal lagoon (Mar Menor, SE Spain).

    PubMed

    Moreno-González, R; Campillo, J A; León, V M

    2013-12-15

    The seasonal distribution of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorine pesticides, organophosphorus pesticides, triazines and other organic pollutants in surface seawater from the Mar Menor lagoon (SE Spain) was characterized from spring 2009 to winter 2010 by stir bar sorptive extraction and thermal desorption followed by capillary gas chromatography coupled to mass spectrometry (SBSE-GC-MS). The most ubiquitous pollutants were chlorpyrifos, chlortal-dimethyl, terbuthylazine, naphthalene and propyzamide throughout the year. Insecticides and herbicides were predominant in summer and spring, and fungicides were more abundant in autumn and winter. Chlorpyrifos was predominant in autumn and spring; herbicides (propyzamide, terbuthylazine and terbuthylazine-desethyl) in autumn and fungicides (flutolanil, boscalid, cyprodinil) in autumn and winter. The highest concentrations for the majority of pollutants were detected in autumn as consequence of air and surface/ground water inputs, and above all of desorption from terrigenous materials deposited in sediments by two intense flash flood events (September 2009).

  5. Field protocol and GIS analysis of connectivity in semiarid headwaters: metrics and evidences from Carcavo Basin (SE Spain)

    NASA Astrophysics Data System (ADS)

    Marchamalo, Miguel; Hooke, Janet; Gonzalez-Rodrigo, Beatriz; Sandercock, Peter

    2017-04-01

    Soil erosion and land degradation are severe problems in headwaters of ephemeral streams in semiarid Mediterranean regions, particularly in marginal upland areas over erodible parent material. Field-based information is required about the main pathways of sediment movement, the identification of sources and sinks and the influence of relevant factors. The EU-funded project RECONDES approached this reality by monitoring connectivity pathways of water and sediment movement in the landscape with the aim of identifying hotspots that could then be strategically targeted to reduce soil erosion and off-site effects. A protocol including field work and GIS analysis was developed and applied to a set of microcatchments in Carcavo Basin (Spain). The philosophy of the protocol was based on the repeated mapping after rainfall events so that frequency of activity of pathways could be evaluated. Connectivity was evaluated for each site and event using specific metrics: maximum mapped connectivity (corresponding to the largest recorded event), density of connected pathway links (m/ha) and frequency of activity (times active/total). Repeated connectivity mapping allowed identifying hotspots of erosion. The effect of structural and functional factors on connectivity was investigated. Field data is also valuable for validating future connectivity models in semiarid landscapes under highly variable and unpredictable conditions.

  6. Magnetostratigraphy of the Orce region (Baza Basin), SE Spain: New chronologies for Early Pleistocene faunas and hominid occupation sites

    NASA Astrophysics Data System (ADS)

    Scott, G. R.; Gibert, Ll.; Gibert, J.

    2007-02-01

    The Orce fossil quarries, in the Baza Basin of southeastern Spain, are a rich source of Early Pleistocene Palaeolithic tools and vertebrate remains. Geologic fieldwork during the last decade has placed these fossiliferous strata within the context of a thick Neogene continental sequence. Detailed lithostratigraphic and magnetostratigraphic results indicate that at least the upper 60 m of this sequence are of Early Pleistocene age. The quarried strata (Venta Micena, Barranco León and Fuentenueva-3) are from a narrow time span (<100 ka) starting before 1.3 Ma. A new, lower excavation at ˜1.5 Ma (Fuentenueva-1 quarry) has a distinctly older fauna. These Orce strata provide a high resolution, Early Pleistocene record of grassland fauna that shows the end of Mammal Neogene fauna (MN17) in the Fuentenueva-1 site (with Gazella borbonica, Equus stenonis) and the beginning of more characteristic Pleistocene fauna in the Venta Micena site (with Hippopotamus antiquus, Equus granatensis, Homo sp.). Thus far, no evidence for human occupation has been found within the earlier Fuentenueva-1 quarry, although many of the same terminal MN17 species have been found with hominids on the other side of Europe at the Dmanisi site (earliest Pleistocene) in the Republic of Georgia.

  7. Initial studies for the phytostabilization of a mine tailing from the Cartagena-La Union Mining District (SE Spain).

    PubMed

    Conesa, Héctor M; Faz, Angel; Arnaldos, Raquel

    2007-01-01

    Mine tailings are one of the main environmental problems in post-mining landscapes and their removal is often complicated due to their high heavy metal content and dimensions. In this sense, using plant species for in situ stabilization may be an interesting and low cost option. Moreover, there are some plant species that have adapted to these conditions and are usually present at these contaminated sites. In this study, a mine tailing located in South-East Spain was investigated in order to establish lines for further phytostabilization research. A plot sampling design was carried out in order to characterize the soil properties. In addition, two plant species that have naturally colonized some parts of the tailing, Hyparrhenia hirta and Zygophyllum fabago, were sampled, including the analyses of their respective rhizospheric soils. The results of plot soil samples showed pH values from ultra acid to slightly alkaline. The electrical conductivity values were around 4dSm(-1) in plots with vegetation and 8dS m(-1) in the plot without vegetation. Total metal concentrations were high (4000 mg kg(-1) for Pb, 9000-15000 mg kg(-1) for Zn). DTPA- and water-extractable Zn were 5% and 3% of the total, respectively. H. hirta accumulated around 150 mg kg(-1) Pb in both shoots and roots. Zn concentration was 750 mg kg(-1) in Z. fabago shoots. DTPA-extractable Zn and Cu were positively correlated to plant uptake.

  8. Impact of mining activities on soils in a semi-arid environment: Sierra Almagrera district, SE Spain.

    PubMed

    Navarro, Andres; Collado, Diego; Carbonell, Montserrat; Sanchez, Juan A

    2004-12-01

    Field and laboratory-column studies were undertaken in order to investigate soil contamination derived from past mining activity in the Sierra Almagrera (SA) district in southeast Spain. The tailings, soil and sediment samples that were collected showed high concentrations of Ag, As, Ba, Cu, Pb, Sb and Zn when analyzed. The mean concentrations of these elements in the tailings were 29.8, 285.4, 54000, 57.7, 2687.5, 179.0 and 2269.0 ppm, respectively. In the soil samples these decreased to 14.3, 96.9, 24700, 37.5, 1859.1, 168.5 and 815.7 ppm, respectively. Geochemical analyses demonstrated high levels of As, Pb and Zn which were above the intervention values set forth in the Andalusian Regulations for Contaminated Soils for As (>50 ppm), Pb (>500 ppm) and Zn (>2000 ppm). Column experiments and mineralogical studies suggest that the dissolution of sulfates and other secondary phases, accumulated in soils and waste-sites during the dry season, acts to control the mobility of metals. The elution curves obtained from column experiments showed a mobilization of Ba, Cu, Pb and Zn, while a low mobility was seen for Ag, As and Sb.

  9. Geostatistical analysis to identify hydrogeochemical processes in complex aquifers: a case study (Aguadulce unit, Almeria, SE Spain).

    PubMed

    Daniele, Linda; Pulido Bosch, Antonio; Vallejos, Angela; Molina, Luis

    2008-06-01

    The Aguadulce aquifer unit in southeastern Spain is a complex hydrogeological system because of the varied lithology of the aquifer strata and the variability of the processes that can take place within the unit. Factorial analysis of the data allowed the number of variables to be reduced to 3 factors, which were found to be related to such physico-chemical processes as marine intrusion and leaching of saline deposits. Variographic analysis was applied to these factors, culminating in a study of spatial distribution using ordinary kriging. Mapping of the factors allowed rapid differentiation of some of the processes that affect the waters of the Gador carbonate aquifer within the Aguadulce unit, without the need to recur to purely hydrogeochemical techniques. The results indicate the existence of several factors related to salinity: marine intrusion, paleowaters, and/or leaching of marls and evaporitic deposits. The techniques employed are effective, and the results conform to those obtained using hydrogeochemical methods (vertical records of conductivity and temperature, ion ratios, and others). The findings of this study confirm that the application of such analytical methods can provide a useful assessment of factors affecting groundwater composition.

  10. Systematic study of the contamination of wastewater treatment plant effluents by organic priority compounds in Almeria province (SE Spain).

    PubMed

    Barco-Bonilla, Nieves; Romero-González, Roberto; Plaza-Bolaños, Patricia; Martínez Vidal, José L; Garrido Frenich, Antonia

    2013-03-01

    The occurrence of priority organic pollutants in wastewater (WW) effluents was evaluated in a semi-arid area, characterized by a high agricultural and tourism activity, as Almeria province (Southeastern Spain). Twelve wastewater treatment plants (WWTPs) were sampled in three campaigns during 2011, obtaining a total of 33 WW samples, monitoring 226 compounds, including pesticides, polycyclic aromatic hydrocarbons (PAHs), phenolic compounds and volatile organic compounds (VOCs). Certain banned organochlorine pesticides such as aldrin, pentachlorobenzene, o,p'-DDD and endosulfan lactone were found, and the most frequently detected pesticides were herbicides (diuron, triazines). PAHs and VOCs were also detected, noting that some of these pollutants were ubiquitous. Regarding phenolic compounds, 4-tertoctylphenol was found in all the WW samples at high concentration levels (up to 89.7 μg/L). Furthermore, it was observed that WW effluent samples were less contaminated in the second and third sampling periods, which corresponded to dry season. This evaluation revealed that despite the WW was treated in the WWTP, organic contaminants are still being detected in WW effluents and therefore they are released into the environment. Finally the risk of environmental threat due to the presence of some compounds in WWTP effluents, especially concerning 4-tertoctylphenol must be indicated.

  11. Habitat Fragmentation in Arid Zones: A Case Study of Linaria nigricans Under Land Use Changes (SE Spain)

    NASA Astrophysics Data System (ADS)

    Peñas, Julio; Benito, Blas; Lorite, Juan; Ballesteros, Miguel; Cañadas, Eva María; Martinez-Ortega, Montserrat

    2011-07-01

    Habitat fragmentation due to human activities is one of the most important causes of biodiversity loss. In Mediterranean areas the species have co-evolved with traditional farming, which has recently been replaced for more severe and aggressive practices. We use a methodological approach that enables the evaluation of the impact that agriculture and land use changes have for the conservation of sensitive species. As model species, we selected Linaria nigricans, a critically endangered plant from arid and semiarid ecosystems in south-eastern Spain. A chronosequence of the evolution of the suitable habitat for the species over more than 50 years has been reconstructed and several geometrical fragmentation indices have been calculated. A new index called fragmentation cadence (FC) is proposed to quantify the historical evolution of habitat fragmentation regardless of the habitat size. The application of this index has provided objective forecasting of the changes of each remnant population of L. nigricans. The results indicate that greenhouses and construction activities (mainly for tourist purposes) exert a strong impact on the populations of this endangered species. The habitat depletion showed peaks that constitute the destruction of 85% of the initial area in only 20 years for some populations of L. nigricans. According to the forecast established by the model, a rapid extinction could take place and some populations may disappear as early as the year 2030. Fragmentation-cadence analysis can help identify population units of primary concern for its conservation, by means of the adoption of improved management and regulatory measures.

  12. Amplitude of late Miocene sea-level fluctuations from karst development in reef-slope deposits (SE Spain)

    NASA Astrophysics Data System (ADS)

    Reolid, Jesús; Betzler, Christian; Braga, Juan Carlos

    2016-11-01

    A prograding late Miocene carbonate platform in southern Spain revealing different sea-level pinning points was analysed with the aim to increase the accuracy of reconstruction of past sea-level changes. These pinning points are distinct diagenetic zones (DZ) and the position of reef-framework deposits. DZ1 is defined by the dissolution of bioclastic components and DZ2 by calcitic cement precipitation in dissolution pores. Calcite cements are granular and radiaxial fibrous, and are of meteoric origin as deduced from cathodoluminescence, EDX spectroscopy, as well as from δ13C and δ18O isotope analyses. DZ3 has moldic porosity after aragonitic bioclasts with minor granular calcitic cements. DZ1 and DZ2 indicate karstification and the development of a coastal palaeoaquifer during a sea-level lowstand. DZ3 diagenetic features are related to the final subaerial exposure of the section during the Messinian Salinity Crisis. Facies and diagenetic data reveal a complete cycle of sea-level fall (23 ± 1 m) and rise (31 ± 1 m). A robust age model based on magneto- and cyclostratigraphy for these deposits places this cycle between 5.89 and 5.87 Ma. Therefore, for the first time, this work allows a direct comparison of an outcrop with a pelagic marine proxy record of a specific Neogene sea-level fluctuation.

  13. Physico-chemical evolution of groundwater in tectonically active areas. Application to the Leana hot spring (Murcia Region, SE Spain)

    NASA Astrophysics Data System (ADS)

    Martínez, M.; Hornero, J.; Trujillo, C.

    2017-03-01

    Seismic events can affect the physico-chemical characteristics of groundwater. These anomalies are of a pre-seismic, co-seismic and post-seismic nature and correspond to pulse variations, sudden increases and decreases without return to initial values and upward or downward changes in trend. Continuous and in situ conductivity and temperature monitoring and periodic water sampling at a hot spring associated with neotectonic activity are of great interest for establishing predictive methods. This method is limited to the seismic activity affecting the fracturing system with which the hot spring is associated. The Region of Murcia and surroundings (southeast Spain) was selected as the study area for exploring the nature of these influences on groundwater. A hot spring in the Leana spa (Murcia) was equipped and monitored during the period 2006-2008, allowing for the in situ determination of conductivity and temperature as well as of major and minor constituents at the laboratory. Due to its proximity and related with fault network, we suggest that 86 % of earthquakes located between 0 and 10 km may affect in situ parameters of groundwater, and 75 % may affect laboratory determinations. This percentage drops in more distant zones. Of all earthquakes that seem to influence groundwater, 55 % of the in situ parameter anomalies and 53 % of laboratory were of a pre-seismic nature.

  14. Physico-chemical evolution of groundwater in tectonically active areas. Application to the Leana hot spring (Murcia Region, SE Spain)

    NASA Astrophysics Data System (ADS)

    Martínez, M.; Hornero, J.; Trujillo, C.

    2016-09-01

    Seismic events can affect the physico-chemical characteristics of groundwater. These anomalies are of a pre-seismic, co-seismic and post-seismic nature and correspond to pulse variations, sudden increases and decreases without return to initial values and upward or downward changes in trend. Continuous and in situ conductivity and temperature monitoring and periodic water sampling at a hot spring associated with neotectonic activity are of great interest for establishing predictive methods. This method is limited to the seismic activity affecting the fracturing system with which the hot spring is associated. The Region of Murcia and surroundings (southeast Spain) was selected as the study area for exploring the nature of these influences on groundwater. A hot spring in the Leana spa (Murcia) was equipped and monitored during the period 2006-2008, allowing for the in situ determination of conductivity and temperature as well as of major and minor constituents at the laboratory. Due to its proximity and related with fault network, we suggest that 86 % of earthquakes located between 0 and 10 km may affect in situ parameters of groundwater, and 75 % may affect laboratory determinations. This percentage drops in more distant zones. Of all earthquakes that seem to influence groundwater, 55 % of the in situ parameter anomalies and 53 % of laboratory were of a pre-seismic nature.

  15. Flash flood events recorded by air temperature changes in caves: A case study in Covadura Cave (SE Spain)

    NASA Astrophysics Data System (ADS)

    Gázquez, Fernando; Calaforra, José María; Fernández-Cortés, Ángel

    2016-10-01

    On 28th September 2012, more than 150 mm rain fell in just two hours in some points of southeastern Spain, triggering intense flash floods that resulted in the death of ten people and widespread material damage. In the gypsum karst of Sorbas, rainfall intensity reached 33 mm/h. Air temperature monitoring in different levels of Covadura Cave, down to 85 m depth, enabled the effect of this extreme episode on the cave microclimate to be evaluated in real time. The cave air temperature increased by between 0.9 and 4.1 °C as a result of water flow into the cavity and intense mixing of air masses, in addition to the displacement of deeper air masses toward shallower levels produced by fast recharge of the surrounding karst aquifer. The lag between peak rainfall intensity and the highest cave air temperature was 5-6 h, indicating the response time of the karst to this rainfall event. No trends with depth were observed, suggesting that water not only flowed in through the main cave entrance but also through secondary accesses and fractures. Furthermore, the size of the cave passages and the intensity of air turbulence generated by waterfalls in the cave played an important role in producing these temperature differences. Even though the rainfall event lasted 10 h, cave air temperature did not return to pre-flash flood values until more than 20 days later. This indicates that, while waterflow through the cave might stop a few hours after the rainfall event, cave air temperature can be affected over a longer period. This can be explained by slow groundwater level decreasing of the surrounding karst aquifer and latent heat liberation produced by moisture condensation on the cave walls. Our results show how continuous monitoring of air temperature in caves can be a useful tool for evaluating the short-term effects of flash floods in subterranean karst systems.

  16. Mapping local microseismicity using short-term tripartite small array installations — Case study: Coy region (SE Spain)

    NASA Astrophysics Data System (ADS)

    Häge, Martin; Joswig, Manfred

    2009-06-01

    One major tectonic feature in the southern part of Spain is the Crevillente Fault Zone (CFZ) which can be traced over 600 km. A short-term microseismic feasibility study was carried out in the area around Coy to investigate the seismic activity of the CFZ by mapping the local seismicity distribution. The area under investigation is of high interest because three moderate earthquakes have occurred nearby since 1999. The measurements were performed with two small arrays, whereas one array was relocated every day to increase the spatial resolution. In the measurement period of 14 nights, including 4 daytime records, 189 events in the magnitude range - 1.8 ≤ ML ≤ 1.3 were detected, of them 133 events could also be located. According to the bulletin of the Instituto Geográfico Nacional, the local network recorded 1 event in the area under investigation in the same period. The results of this short-term measurement show an increased detectability by using small arrays for event recording and prove that there is a high rate of microseismicity below the detection threshold of the local network. For event location, the regional velocity model had to be adapted to our small scale, short epicentral distance application by reducing vP to 4 km/s using a homogenous half space model. The distribution of the events does not indicate a seismic activity along the CFZ. It is rather concentrated to the south around the epicentral zone of the La Paca earthquake that occurred 114 days before our measurement campaign. Some events show a high waveform similarity. They can be attributed to the same fault segment.

  17. Habitat fragmentation in arid zones: a case study of Linaria nigricans under land use changes (SE Spain).

    PubMed

    Peñas, Julio; Benito, Blas; Lorite, Juan; Ballesteros, Miguel; Cañadas, Eva María; Martinez-Ortega, Montserrat

    2011-07-01

    Habitat fragmentation due to human activities is one of the most important causes of biodiversity loss. In Mediterranean areas the species have co-evolved with traditional farming, which has recently been replaced for more severe and aggressive practices. We use a methodological approach that enables the evaluation of the impact that agriculture and land use changes have for the conservation of sensitive species. As model species, we selected Linaria nigricans, a critically endangered plant from arid and semiarid ecosystems in south-eastern Spain. A chronosequence of the evolution of the suitable habitat for the species over more than 50 years has been reconstructed and several geometrical fragmentation indices have been calculated. A new index called fragmentation cadence (FC) is proposed to quantify the historical evolution of habitat fragmentation regardless of the habitat size. The application of this index has provided objective forecasting of the changes of each remnant population of L. nigricans. The results indicate that greenhouses and construction activities (mainly for tourist purposes) exert a strong impact on the populations of this endangered species. The habitat depletion showed peaks that constitute the destruction of 85% of the initial area in only 20 years for some populations of L. nigricans. According to the forecast established by the model, a rapid extinction could take place and some populations may disappear as early as the year 2030. Fragmentation-cadence analysis can help identify population units of primary concern for its conservation, by means of the adoption of improved management and regulatory measures.

  18. Flowstones from SE Spain document a close relationship between North Atlantic temperature and precipitation in the Western Mediterranean between 7 and 112 ka

    NASA Astrophysics Data System (ADS)

    Budsky, Alexander; Scholz, Denis; Mertz-Kraus, Regina; Spötl, Christoph; Gibert, Luis; Jochum, Klaus Peter

    2017-04-01

    Here we present three flowstone records from Cueva Victoria, SE Spain, covering the period between Marine Isotope Stage (MIS) 5 and MIS 3, the Late Glacial and the Holocene. The flowstones were precisely dated by the MC-ICPMS 230Th/U-method. In addition, stable oxygen and carbon isotope ratios as well as trace element concentrations were determined at high resolution (centennial to decadal scale). Present-day climate of SE Spain is classified as semi-arid with dry summer months (<10 mm/month precipitation) and sparsely developed vegetation. A large dataset of 230Th/U ages on several flowstones from Cueva Victoria indicates preferential flowstone growth during warm phases (i.e., interglacials as well as warm interstadials), whereas flowstone growth is interrupted during glacial phases (Budsky et al., 2015). One of the drill cores shows more or less continuous flowstone growth between the Last Interglacial (MIS 5) and MIS 3 (112 - 46 ka). A flowstone from another part of the cave only records the time span from 86 to 50 ka including several growth interruptions. However, both flowstones cover the transition from MIS 4 to 3 including D/O events 17 to 13 at high resolution. Each D/O event is reflected by a remarkable decrease in both δ18O and δ13C values (both up to 3‰ ) accompanied by decreasing concentrations of Mg and Sr. In particular, longer D/O events, lasting several thousands of years (e.g., D/O 14, 19, 20 and 21), are well represented in the δ18O and δ13C records. The timing is in good agreement with the NGRIP ice core and sea-surface temperatures from the Iberian margin. δ18O values are around -3.5 ‰ and decrease to -5 to -6 ‰ during D/O events, while δ13C values are around -9 ‰ and decrease to -10 to -11 ‰ ) during D/O events. We interpret these changes as more humid conditions during D/O events, with elevated sea-surface temperatures in the North Atlantic and the Mediterranean Sea leading to increased moisture transport and precipitation on

  19. Archaeomagnetic evidence of temporal diachronies in Middle-Palaeolithic palimpsests. A case study from El Salt (SE Spain)

    NASA Astrophysics Data System (ADS)

    Herrejón Lagunilla, Ángela; Carrancho, Ángel; José Villalaín, Juan; Mallol, Carolina; Hernández, Cristo Manuel; Galván, Bertila

    2017-04-01

    Archaeomagnetism is a very useful tool to the study of Palaeolithic palimpsests and this line of research is almost unexplored. Middle Palaeolithic palimpsests (ca. 250 - 40 ky BP) as El Salt site (Alcoy, Spain) contain a big amount of hearths with thousands of lithic and faunal remains associated to them. Most of these hearths and associated materials are so densely overlapped that individualization of human occupations discerning temporal differences is virtually impossible. Archaeomagnetism can be very helpful to that aim. In this work the goal of archaeomagnetic study is not to obtain a dating since no palaeosecular variation (PSV) curve for that age is available, but to identificate diachronies between hearths exposed on the same palaeosurface. It is archaeologically relevant as that information cannot be often easily determined. For this purpose, an archaeomagnetic study has been carried out on some hearths from El Salt unit X (ca. 50-55 ky BP). Assuming that each hearth recorded the Earth's magnetic field (EMF) direction during the last cooling by means of a thermoremanence (TRM), here is proposed a hypothesis to temporally dissect palimpsests: if the mean directions obtained from two (or more) hearths are statistically distinguishable, directional differences can be interpreted in terms of the PSV of EMF, being therefore diachronic. The mean archaeomagnetic direction from each hearth was calculated. Statistical tests were performed in order to evaluate if the means are distinguishable. In case of distinguishable means, the angle among directions was calculated. Assuming that the features of the EMF during the Middle Palaeolithic were similar to those during Holocene times, the geomagnetic field model SHA.DIF.14K (Pavón-Carrasco et al. 2014) was used to interpret these angle deviations in temporal terms. Series of angles between successive directions of the EMF separated by intervals of 50/100/200/400/800 years for the last 5000 years were calculated from

  20. Active shallow extension in central and eastern Betic Cordillera from CGPS data

    NASA Astrophysics Data System (ADS)

    Galindo-Zaldivar, J.; Gil, A. J.; Sanz de Galdeano, C.; Lacy, M. C.; García-Armenteros, J. A.; Ruano, P.; Ruiz, A. M.; Martínez-Martos, M.; Alfaro, P.

    2015-11-01

    The Betic Cordillera is an Alpine belt formed in the western Mediterranean by the westward displacement of the Alboran Domain in between the Eurasian and African convergent plates. New CGPS data from the central and eastern Betic Cordillera and its foreland-obtained mainly from the Topo-Iberia project-allowed us to precisely determine the rate of tectonic deformation. Most of the displacements of the central and eastern Betics are westward, with a variable southwestward component, in relation to the Eurasian stable plate. While in the Iberian foreland the displacements are extremely low, some deformation related to low compressional deformation occurs in the easternmost foreland basin and eastern Betic Cordillera. The displacement increases substantially southwards and westwards in relation to present-day extensional deformation. Major active discontinuities correspond to the NW-SE normal fault zones, which dip westwards; they are located in Almeria-Tabernas; Balanegra, and western Sierra de Gador; whereas the Padul fault zone located west of Sierra Nevada extends northwards to the Granada Basin. NW-SE extensional faults are also observed to the north, in the Baza Basin. Moreover, the activity of dextral faults along the Sorbas-Tabernas-Alpujarras-Guajares band, generally considered as a transfer fault zone, is evidenced by the displacement data. These results come to demonstrate the low activity or inactivity of the large northern E-W oriented folds of the central and eastern Internal Zone, such as the Sierra de Los Filabres antiform. They also point to the possible residual activity of the northern part of the NE-SW Sierra Nevada antiform, where the maximum relief of the Cordillera is found. Altogether, our data support a heterogeneous present-day westward extension that affects the upper crust of the Betic Cordillera and increases towards the thinned continental crust of the Alboran Sea and towards the west, which is compatible with roll-back subduction along

  1. Chronology for the Cueva Victoria fossil site (SE Spain): Evidence for Early Pleistocene Afro-Iberian dispersals.

    PubMed

    Gibert, Luis; Scott, Gary R; Scholz, Denis; Budsky, Alexander; Ferràndez, Carles; Ribot, Francesc; Martin, Robert A; Lería, María

    2016-01-01

    Cueva Victoria has provided remains of more than 90 species of fossil vertebrates, including a hominin phalanx, and the only specimens of the African cercopithecid Theropithecus oswaldi in Europe. To constrain the age of the vertebrate remains we used paleomagnetism, vertebrate biostratigraphy and (230)Th/U dating. Normal polarity was identified in the non-fossiliferous lowest and highest stratigraphic units (red clay and capping flowstones) while reverse polarity was found in the intermediate stratigraphic unit (fossiliferous breccia). A lower polarity change occurred during the deposition of the decalcification clay, when the cave was closed and karstification was active. A second polarity change occurred during the capping flowstone formation, when the upper galleries were filled with breccia. The mammal association indicates a post-Jaramillo age, which allows us to correlate this upper reversal with the Brunhes-Matuyama boundary (0.78 Ma). Consequently, the lower reversal (N-R) is interpreted as the end of the Jaramillo magnetochron (0.99 Ma). These ages bracket the age of the fossiliferous breccia between 0.99 and 0.78 Ma, suggesting that the capping flowstone was formed during the wet Marine Isotopic Stage 19, which includes the Brunhes-Matuyama boundary. Fossil remains of Theropithecus have been only found in situ ∼1 m below the B/M boundary, which allows us to place the arrival of Theropithecus to Cueva Victoria at ∼0.9-0.85 Ma. The fauna of Cueva Victoria lived during a period of important climatic change, known as the Early-Middle Pleistocene Climatic Transition. The occurrence of the oldest European Acheulean tools at the contemporaneous nearby site of Cueva Negra suggest an African dispersal into SE Iberia through the Strait of Gibraltar during MIS 22, when sea-level was ∼100 m below its present position, allowing the passage into Europe of, at least, Theropithecus and Homo bearing Acheulean technology.

  2. Triclinic Transpression in brittle shear zones evaluated via combined numerical and analogue modeling: the case of The Torcal de Antequera Massif, SE Spain.

    NASA Astrophysics Data System (ADS)

    Barcos, Leticia; Díaz-Azpiroz, Manuel; Faccenna, Claudio; Balanyá, Juan Carlos; Expósito, Inmaculada; Giménez-Bonilla, Alejandro

    2013-04-01

    Numerical kinematic models have been widely used to understand the parameters controlling the generation and evolution of ductile transpression zones. However, these models are based on continuum mechanics and therefore, are not as useful to analyse deformation partitioning and strain within brittle-ductile transpression zones. The combination of numerical and analogue models will potentially provide an effective approach for a better understanding of these processes and, to a broader extent, of high strain zones in general. In the present work, we follow a combined numerical and analogue approach to analyse a brittle dextral transpressive shear zone. The Torcal de Antequera Massif (TAM) is part of a roughly E-W oriented shear zone at the NE end of the Western Gibraltar Arc (Betic Cordillera). This shear zone presents, according to their structural and kinematic features, two types of domains i) Domain type 1 is located at both TAM margins, and is characterized by strike-slip structures subparallel to the main TAM boundaries (E-W). ii) Domain type 2 corresponds to the TAM inner part, and it presents SE-vergent open folds and reverse shear zones, as well as normal faults accommodating fold axis parallel extension. Both domains have been studied separately applying a model of triclinic transpression with inclined extrusion. The kinematic parameters obtained in this study (?, ? and Wk) allows us to constrain geometrical transpression parameters. As such, the angle of oblique convergence (α, the horizontal angle between the displacement vector and the strike of the shear zone) ranges between 10-17° (simple shear dominated) for domain type 1 and between 31-35° (coaxial dominated) for domain type 2. According to the results obtained from the numerical model and in order to validate its possible utility in brittle shear zones we develop two analogue models with α values representative of both domains defined in the TAM: 15° for type 1 and 30° for type 2. In the

  3. Mud volcanism and authigenic carbonates related to methane-rich fluids migration in the late Neogene marls of S.E. Spain

    NASA Astrophysics Data System (ADS)

    Pierre, C.; Blanc-Valleron, M. M.; Rouchy, J. M.

    2015-12-01

    Methane-rich fluids that are generated at depth in organic-rich deposits migrate within the sediments to the seafloor where they are expelled to form mud volcanoes or pockmarks. Moreover, these migrating fluids are involved in diagenetic processes as authigenic carbonate formation and they may participate to gas hydrate formation. These features are well-known in the present-day continental margins but their fossil records are relatively scarce. The outcropping Tortonian and Messinian marls in S.E. Spain basins (Lorca, Fortuna, Columbares, Huercal Overa) contain abundant authigenic dolomite nodules. The oxygen and carbon isotopic compositions of these dolomites exhibit wide ranges (-1.4 < δ18O < +5.6 ; -25.6 < δ13C < +9.3) indicating that carbonate precipitation occurred within the marly sediments due to circulation of fluids modified by gas hydrates formation/dissociation, where anaerobic oxidation of methane and methanogenesis were active. In the Huercal Overa basin, there is a well-preserved mud volcano intruding vertically the Messinian marls. These two features, methane derived authigenic dolomites and mud volcanism, are testifying of the intense methane-rich fluid migration in the marly deposits of the western Mediterranean basins during the late Neogene, which was the time of major paleoenvironmental changes in the Mediterranean sea climaxing during the Messinian salinity crisis.

  4. Chronological and environmental context of the first hominin dispersal into Western Europe: The case of Barranco León (Guadix-Baza Basin, SE Spain).

    PubMed

    Agustí, Jordi; Blain, Hugues-Alexandre; Lozano-Fernández, Iván; Piñero, Pedro; Oms, Oriol; Furió, Marc; Blanco, Angel; López-García, Juan Manuel; Sala, Robert

    2015-10-01

    The early Pleistocene site of Barranco León (Guadix-Baza Basin, SE Spain), dated to 1.4 Ma (millions of years ago), records the oldest hominin occurrence in Western Europe, as evidenced by the discovery of one tooth and thousands of Mode 1 stone tools. In this paper a detailed analysis of the microvertebrate content of the D1 and D2 units from this site is presented. The early Pleistocene in the Guadix-Baza Basin is characterized by a sharp climatic deterioration, which possibly impeded the settlement of this region by the early hominin population from the southern Caucasus. Shortly afterwards, when the climatic conditions were again favorable, a hominin presence is suddenly evidenced at the units D1 and D2 of Barranco León. According to the microvertebrate analysis of these units, the mean annual temperature at the time of deposition was significantly higher than 13 °C, with prevalent humid conditions. However, although most of the species were inhabitants of water edges, an open landscape was present in the vicinity of the lake. The data reported here clearly support the idea that the early hominin occupation of Europe was strongly constrained by climatic and environmental conditions, rather than by physiography or cultural factors.

  5. Evaluation of the Olduvai subchron in the Orce ravine (SE Spain). Implications for Plio-Pleistocene mammal biostratigraphy and the age of Orce archeological sites

    NASA Astrophysics Data System (ADS)

    Gibert, L.; Scott, G.; Ferràndez-Cañadell, C.

    2006-03-01

    The Barranco de Orce (BO) section in the Baza basin (SE Spain) exposes several fossiliferous layers (O-1 to O-7) with Plio-Pleistocene micro- and macromammals. Biostratigraphic and magnetostratigraphic data from this and other sections in the basin have been extensively used to calibrate the Plio-Pleistocene chronology based on mammal biozonations. Because of its stratigraphic and geographic proximity, the BO section has also been used to date the paleontological and archeological sites of Barranco León, Fuentenueva-3 and Venta Micena. This study shows that the BO section crosses a mega-landslide that produces partial repetitions of the sedimentary sequence. The seven fossiliferous layers are actually the repetition of only two (O-6 and O-7) which are found in situ in the upper part of the ravine. New paleomagnetic results demonstrate the presence of Reverse magnetization throughout this section, contradicting the Normal event previously reported and assigned to the 'Olduvai' subchron (C2n). Published and new magnetostratigraphic data show that all archeological and paleontological sites in the Orce area are within a Reverse magnetochron, presumably C1r.2r (late Matuyama). The use of BO in the magnetobiostratigraphical calibration of the Pliocene/Pleistocene boundary for western Europe is not advised.

  6. The beach placer iron deposit of Portman Bay, Murcia, SE Spain: the result of 33 years of tailings disposal (1957-1990) to the Mediterranean seaside

    NASA Astrophysics Data System (ADS)

    Manteca, José Ignacio; López García, José Ángel; Oyarzun, Roberto; Carmona, Carlos

    2014-08-01

    Between 1957 and 1990, the Peñarroya Mining and Metallurgical Company (SMMPE) disposed about 60 million tonnes of tailings materials directly to the Mediterranean Sea. A substantial part of it (12.5 Mt) was dragged back by the sea currents progressively infilling the Portman Bay (Murcia, SE Spain), thus making the shoreline advance between 500 and 600 m seaward. The Roberto froth flotation plant processed mineral from manto-type deposits belonging to the Sierra de Cartagena-La Unión lead-zinc district. One of the mineral assemblages present in these deposits comprises greenalite, magnetite, sulfides, carbonates, and silica. Despite that magnetite recovery was undertaken by SMMPE between 1959 and 1967, we estimate that magnetite contained in the tailings hosts a substantial resource that could be as large as 2.3 Mt of iron ore. The ore contains magnetite ± hematite ± siderite. Tidal waves and sea currents led to gravimetric classification of the tailings material, with concentration of the dense iron oxides in the sandy fractions, eventually forming a coastal placer iron deposit. A major problem for magnetic separation is the intimate intergrowth between magnetite, hematite, and siderite. Besides, the sands contain large concentrations of Pb (0.27 %), Zn (0.72 %), and As (559 ppm).

  7. Combining radon, short-lived radium isotopes and hydrodynamic modeling to assess submarine groundwater discharge from an anthropized semiarid watershed to a Mediterranean lagoon (Mar Menor, SE Spain)

    NASA Astrophysics Data System (ADS)

    Baudron, Paul; Cockenpot, Sabine; Lopez-Castejon, Francisco; Radakovitch, Olivier; Gilabert, Javier; Mayer, Adriano; Garcia-Arostegui, José Luis; Martinez-Vicente, David; Leduc, Christian; Claude, Christelle

    2015-06-01

    In highly anthropized watersheds, surface water tributaries may carry unexpected high quantities of radon and radium to coastal lagoons. Investigating submarine groundwater discharge (SGD) with radionuclide tracers is therefore a complex task. In order to quantify SGD and decipher the influence of the different water sources, we combined a radon (222Rn) and short-lived radium (223Ra, 224Ra) survey with the hydrodynamic modeling of a lagoon. We applied it to the Mar Menor lagoon (SE Spain) where surface water tributaries and undocumented emissaries carry water from groundwater drainage and brines from groundwater desalinization. We identified the areas of influence of the plume of radionuclides from the river, located major areas of SGD and proposed a location for two submarine emissaries. Porewater, i.e. interstitial water from underlying sediments, was found to be the most representative SGD end member, compared to continental groundwater collected from piezometers. Mass balances in winter and summer seasons provided yearly SGD fluxes of water of 0.4-2.2 ṡ 108 m3/y (222Rn), 4.4-19.0 ṡ 108 m3/y (224Ra) and 1.3 ṡ 108 m3/y (223Ra, measured in winter only). Tidal pumping was identified as a main driver for recirculated saline groundwater, while fresh submarine groundwater discharge from the aquifer ranged between 2% and 23% of total SGD.

  8. Regional subsidence modelling in Murcia city (SE Spain) using 1-D vertical finite element analysis and 2-D interpolation of ground surface displacements

    NASA Astrophysics Data System (ADS)

    Tessitore, S.; Fernández-Merodo, J. A.; Herrera, G.; Tomás, R.; Ramondini, M.; Sanabria, M.; Duro, J.; Mulas, J.; Calcaterra, D.

    2015-11-01

    Subsidence is a hazard that may have natural or anthropogenic origin causing important economic losses. The area of Murcia city (SE Spain) has been affected by subsidence due to groundwater overexploitation since the year 1992. The main observed historical piezometric level declines occurred in the periods 1982-1984, 1992-1995 and 2004-2008 and showed a close correlation with the temporal evolution of ground displacements. Since 2008, the pressure recovery in the aquifer has led to an uplift of the ground surface that has been detected by the extensometers. In the present work an elastic hydro-mechanical finite element code has been used to compute the subsidence time series for 24 geotechnical boreholes, prescribing the measured groundwater table evolution. The achieved results have been compared with the displacements estimated through an advanced DInSAR technique and measured by the extensometers. These spatio-temporal comparisons have showed that, in spite of the limited geomechanical data available, the model has turned out to satisfactorily reproduce the subsidence phenomenon affecting Murcia City. The model will allow the prediction of future induced deformations and the consequences of any piezometric level variation in the study area.

  9. The economic value of conjoint local management in water resources: Results from a contingent valuation in the Boquerón aquifer (Albacete, SE Spain).

    PubMed

    Rupérez-Moreno, Carmen; Pérez-Sánchez, Julio; Senent-Aparicio, Javier; del Pilar Flores-Asenjo, Maria

    2015-11-01

    In the field of water resources management, the Water Framework Directive is the first directive to adopt an ecosystem approach, establishing principles and economic tools for an integrated management of water resources to protect, conserve and restore all water bodies. The incorporation of local authorities in this management involves quality benefits that are perceived by users in an effective and lasting way. The purpose of this paper is to present the economic value of the environmental recovery of the overexploited Boquerón aquifer in Hellín (Albacete, SE Spain) and all of its associated ecosystems. This aquifer operates as a regulating reservoir for the surface waters of the Hellín Canal. The contingent valuation method (CVM) applied in this environmental assessment of the aquifer showed that its non-use value was €147,470 per year, due to the high environmental awareness of the Hellín people, which is enough to ensure the survival of the ecosystems linked to the aquifer.

  10. [Incurable disease in Spain during the 19th century. The Hospital para Hombres Incurables Nuestra Señora del Carmen].

    PubMed

    Zaragoza, Juan Manuel

    2012-01-01

    This paper examines the State's assumption of medical care for patients with "permanent needs" in 19th century Spain. These patients were the incurably ill, the chronically ill and the elderly. This process is contextualized within the liberal reforms of the Spanish healthcare system in the reign of Isabel 11 (1833-1868). The goal of these reforms was the creation and consolidation of a national health system that would gradually replace the religious health charities. Healthcare reform became necessary due to the increase in migration that started in the 1830's and intensified in the 1850's. Traditional care networks formed by the family, local community and religious charities were no longer available to those who had left their village or town. In addition, many religious charities were bankrupted by the seizure of their properties in a programme of confiscation. Similar healthcare reform processes were taking place in the United Kingdom, France and Germany, among other European countries, and involved significant changes in the lives of patients, who became strictly controlled and medicalised. My aim was to identify changes in the patients' experience of illness through a case study of the living conditions of inmates at the Nuestra Señora del Carmen Hospital for Incurable Men, based in Madrid from 1852 to 1949. This was one of the institutions devoted to caring for patients with "permanent needs" and was under the direct control of the General State Administration.

  11. Environmental assessment of the arsenic-rich, Rodalquilar gold-(copper-lead-zinc) mining district, SE Spain: data from soils and vegetation

    NASA Astrophysics Data System (ADS)

    Oyarzun, Roberto; Cubas, Paloma; Higueras, Pablo; Lillo, Javier; Llanos, Willians

    2009-08-01

    The Rodalquilar mineral deposits (SE Spain) were formed in Miocene time in relation to caldera volcanic episodes and dome emplacement phenomena. Two types of ore deposits are recognized: (1) the El Cinto epithermal, Au-As high sulphidation vein and breccia type; and (2) peripheral low sulphidation epithermal Pb-Zn-Cu-(Au) veins. The first metallurgical plants for gold extraction were set up in the 1920s and used amalgamation. Cyanide leaching began in the 1930s and the operations lasted until the mid 1960s. The latter left a huge pile of ~900,000-1,250,000 m3 of abandoned As-rich tailings adjacent to the town of Rodalquilar. A frustrated initiative to reactivate the El Cinto mines took place in the late 1980s and left a heap leaching pile of ~120,000 m3. Adverse mineralogical and structural conditions favoured metal and metalloid dispersion from the ore bodies into soils and sediments, whereas mining and metallurgical operations considerably aggravated contamination. We present geochemical data for soils, tailings and wild plant species. Compared to world and local baselines, both the tailings and soils of Rodalquilar are highly enriched in As (mean concentrations of 950 and 180 μg g-1, respectively). Regarding plants, only the concentrations of As, Bi and Sb in Asparagus horridus, Launaea arborescens, Salsola genistoides, and Stipa tenacissima are above the local baselines. Bioaccumulation factors in these species are generally lower in the tailings, which may be related to an exclusion strategy for metal tolerance. The statistical analysis of geochemical data from soils and plants allows recognition of two well-differentiated clusters of elements (As-Bi-Sb-Se-Sn-Te and Cd-Cu-Hg-Pb-Zn), which ultimately reflect the strong chemical influence of both El Cinto and peripheral deposits mineral assemblages.

  12. A descriptive and quantitative approach regarding erosion and development of landforms on abandoned mine tailings: New insights and environmental implications from SE Spain

    NASA Astrophysics Data System (ADS)

    Martín Duque, J. F.; Zapico, I.; Oyarzun, R.; López García, J. A.; Cubas, P.

    2015-06-01

    - 1 y- 1, which matches well typical values for erosion of mined areas, commonly above 100 Mg (MT) ha- 1 y- 1. Abandoned mine tailing deposits are extremely common in the semiarid scenarios of the SW USA, Australia, Chile, and Peru. Given the similarities of these scenarios with SE Spain, the example from Mazarrón may provide useful new insights regarding the erosion and geomorphic evolution of such tailing deposits. These matters should be addressed in key environmental actions such as mine closure plans and land reclamation projects. A solution may come via restoration of these deposits through landform design involving the building up of stable mature landscapes, which in turn can withstand erosion much more easily.

  13. Preliminary results in larger benthic foraminifera assemblage in a mixed siliciclastic-carbonate platform from the Upper Cretaceous of the External Prebetic Domain (Valencia province, SE Spain)

    NASA Astrophysics Data System (ADS)

    Robles-Salcedo, Raquel; Vicedo, Vicent

    2016-04-01

    In the External Prebetic Domain (Betic Mountain Range, Valencia province, SE Spain) it is difficult to find good outcrops to study larger benthic foraminifera (LBF), particularly in the Upper Cretaceous deposits, because of three main reasons. During the Upper Cretaceous, the complex paleogeography in the northern Prebetic Domain developed a complex system of shallow-water platforms. This is directly linked to the complexity in the distribution of the facies observed nowadays, which may change drastically in lateral, closely related outcrops having a special negative impact in the lateral extension of stratigraphical levels containing LBF. The second reason is the nature of the shallow water environments in which the larger foraminifera lived. The local continental influence derived in the establishment of very complex mixed platforms. Thus, there is not a complete register through carbonate rocks, but an alternation of microconglomerates, sandstones, calcarenites and carbonates that can be observed in the stratigraphic series of the Upper Cretaceous. This affects negatively in observing changes in the evolutionary trends of taxa. The third reason difficulting the study of LBF in northern localities of the Prebetic Domain is diagenetic. Dolomitization affects a huge part of the Mesozoic rocks deleting all fossil microfauna in the affected rocks. Such three reasons are behind the difficulty in developing correlations and having a comprehensive understanding of the biostratigraphy and phylogeny of the taxa involved. However, after several field trips developed in the northern Prebetic area, an excellent reference section for the study of the LBF in the Prebetic Domain has been identified in the surroundings of the Pinet village (Valencia province). Here, a relatively continuous section with scarce dolomitization and good conditions of accessibility exists. The larger foraminifera assemblages appering in the Pinet section will be compared with other paleobiogeographic

  14. Lacustrine basin dynamics and organosulphur compound origin in a carbonate-rich lacustrine system (Late Oligocene Mequinenza Formation, SE Ebro Basin, NE Spain)

    NASA Astrophysics Data System (ADS)

    Cabrera, L.; Cabrera, M.; Gorchs, R.; de las Heras, F. X. C.

    2002-04-01

    The Late Oligocene Mequinenza formation (SE Ebro Basin, NE Spain) records the development of extensive, shallow, low-gradient lacustrine zones, which evolved under a subtropical, warm climatic regime, affected by humidity-aridity cycles. Carbonate-dominated inner lacustrine sequences, which include thin coal seams, are laterally related to muddy carbonate and siliciclastic marginal lacustrine assemblages where evaporites occur. Water solute concentration of the lacustrine zones changed during the alternative high- and low-stand episodes, with lacustrine waters ranging mainly from fresh to oligosaline. Nonsulphurised (NSC) and sulphurised (OSC) organic compounds occur in the inner lacustrine facies and record significant contributions from aquatic and terrestrial higher plants, bacteria (cyanobacteria, photosynthetic anaerobic bacteria) and algae. These biomarkers show that the lacustrine system was eutrophic and the water column was poorly oxygenated and sometimes stratified, as evidenced by occasional finely laminated facies and gammacerane. Organic matter S/C ratio (lower in carbonate than in coal and coal-related facies) suggests significant variations in the lacustrine autotrophic production and/or the allochthonous organic matter contribution. Higher plant biomarkers were recorded mainly as normal, nonsulphurised lipids. By contrast, bacterial and algal lipids (hopanoids, steroids and isoprenoids), under intense sulphate reduction conditions, incorporated sulphur in their hydrocarbon skeleton and gave rise to OSC with distributions of thienyl and thiolanylhopanoids, epithiosteranes and polyprenoids. Linear thiols are new biomarkers, which probably were generated by the early incorporation of sulphur into funtionalised precursors (e.g., alkanols). Intense methanogenesis was enhanced in some lacustrine zones owing to high organic matter input and, as a consequence, biomarkers of methanotrophic and methylotrophic bacteria, related to methane emission, are also

  15. The growth of pines germinated from woodchip mulch in restored soils from semiarid SE Spain quarries is enhanced by organic amendments

    NASA Astrophysics Data System (ADS)

    Luna Ramos, Lourdes; Miralles, Isabel; Lázaro-Suau, Roberto; Solé-Benet, Albert

    2017-04-01

    The use of pine woodchips in soil restoration in calcareous quarries is a relatively low-cost mulching technique to improve soil water conservation and decrease soil erosion, contributing to improve soil quality. Besides these two important effects, woodchip mulch is also a potential source of seeds which can germinate if environmental conditions during earlier stages are adequate. Pine germination has been observed in experimental plots treated with pine woodchips used as mulch in one of the driest regions in Europe (SE Spain). This side-effect provided an interesting opportunity to analyse the influence of topsoil and two organic wastes (compost from domestic organic waste and sewage sludge from urban water treatment plant) in mine soils on the germinated pines (Pinus halepensis Mill.) and the plant cover (revegetated native plants and spontaneous vegetation). Number, height and basal diameter of pines and the total plant cover were measured 6 years after the applications of topsoil and organic amendments. Results showed that organic wastes increased the pine growth and the total plant cover which could favour in turn the physico-chemical soil properties and its quality in the medium-long term. However, organic amendments negatively influencing the number of germinated pines. The likely growth of pine seedlings derived from the pine cones which come with pine woodchips used as mulch, when enhanced by organic amendments, adds a positive value in quarry restoration even under very dry climatic conditions. However, it is necessary to continue monitoring the development of vegetation to form a more precise idea about whether the development of the pines is globally beneficial, since the pines could outcompete the local native plants.

  16. The Cartagena-La Unión mining district (SE Spain): a review of environmental problems and emerging phytoremediation solutions after fifteen years research.

    PubMed

    Conesa, Héctor M; Schulin, Rainer

    2010-06-01

    After mining in the Cartagena-La Unión Mining District (SE Spain) was discontinued in 1992, various studies have shown that large amounts of toxic metals continue to be transferred with the spread of unstabilized mining wastes to the nearby ecosystems. Local creeks seem to be important pathways carrying eroded materials from the headwaters to the nearby coastal areas of the Mediterranean Sea. Studies have shown the presence of high metal concentrations in the sediments of riverbeds and in river mouths and adjacent coastal marshes (e.g. 500 mg kg(-1) As; 12 000 mg kg(-1) Pb). Also, some nearby agricultural areas are affected (up to 10 mg kg(-1) Pb in lettuce leaves). Metal transfer into biota has been demonstrated in creek sediments in relation to benthic organisms (up to 222 mg kg(-1) Pb in molluscs). The mining wastes in the area are spontaneously colonized by native plant species. On the tailings, most of the plant species are grasses (e.g. Lygeum spartum, Piptatherum miliaceum); in polluted salt marshes, halophytic species dominate (e.g. Arthrocnemum macrostachyum). Metal uptake by plants is in general low (10 mg kg(-1) for Cu; <200 mg kg(-1) Pb; <500 mg kg(-1) Zn). Preliminary tests have shown the suitability of amendments (e.g. lime, fertilizer, pig manure) to improve the establishment of certain vegetation on the tailings. Phytostabilization appears to be a promising technology to decrease erosion in the tailings. However, tailings must be individually analysed in order to determine their geostructural stability, as in addition, mechanical stabilization will be needed in some cases to prevent collapse.

  17. Resource availability and competition intensity in the carnivore guild of the Early Pleistocene site of Venta Micena (Orce, Baza Basin, SE Spain)

    NASA Astrophysics Data System (ADS)

    Rodríguez-Gómez, Guillermo; Palmqvist, Paul; Ros-Montoya, Sergio; Espigares, M. Patrocinio; Martínez-Navarro, Bienvenido

    2017-05-01

    With an age of ∼1.6-1.5 Ma, the Early Pleistocene site of Venta Micena (Orce, Baza Basin, SE Spain) has provided the large mammals assemblage of Late Villafranchian age with higher preservational completeness in Western Europe and offers a unique opportunity to analyze the food webs of the mammalian paleocommunity before the first human arrival in this continent. Taphonomic analysis of the fossil assemblage has shown evidence of carnivore involvement, particularly hyenas, in the bone accumulating process. In this study we use a mathematical approach based on Leslie matrices to quantify the biomass of ungulates available to the members of the carnivore guild as well as the pattern of resource partitioning and competition intensity among them. The results obtained show that although the biomass of primary consumers available to the secondary consumers was lower than the value expected under optimal conditions, more than half the individuals and biomass of carnivores expected would be reached, which allowed a viable ecosystem in Venta Micena. In fact, the biomass available for the members of the carnivore guild is 25-30% greater than the estimates obtained for two nearby sites, Barranco León-D and Fuente Nueva-3, which are somewhat younger (∼1.4 Ma) and preserve the oldest evidence on human presence in this region. Given that the competition intensity estimated in the carnivore guild of Venta Micena was lower than in the latter sites, this suggests that the timing of the first human dispersal in Western Europe was probably not a matter of ecological opportunity.

  18. Multiband PSInSAR and long-period monitoring of land subsidence in a strategic detrital aquifer (Vega de Granada, SE Spain): An approach to support management decisions

    NASA Astrophysics Data System (ADS)

    Mateos, Rosa María; Ezquerro, Pablo; Luque-Espinar, Juan Antonio; Béjar-Pizarro, Marta; Notti, Davide; Azañón, Jose Miguel; Montserrat, Oriol; Herrera, Gerardo; Fernández-Chacón, Francisca; Peinado, Tomás; Galve, Jorge Pedro; Pérez-Peña, Vicente; Fernández-Merodo, Jose A.; Jiménez, Jorge

    2017-10-01

    This work integrates detailed geological and hydrogeological information with PSI data to obtain a better understanding of subsidence processes detected in the detrital aquifer of the Vega de Granada (SE Spain) during the past 13 years. Ground motion was monitored by exploiting SAR images from the ENVISAT (2003-2009), Cosmo-SkyMed (2011-2014) and Sentinel-1A (2015-2016) satellites. PSInSAR results show an inelastic deformation in the aquifer and small land surface displacements (up to -55 mm). The most widespread land subsidence is detected during the ENVISAT period (2003-2009), which coincided with a long, dry period in the region. The highest displacement rates recorded during this period (up to 10 mm/yr) were detected in the central part of the aquifer, where many villages are located. For this period, there is a good correlation between groundwater level depletion and the augmentation of the average subsidence velocity and slight hydraulic head changes (<2 m) have a rapid ground motion response. The Cosmo-SkyMed period (2011-2014) coincided with a rainy period, and the land subsidence is only concentrated in some points. Rates of average subsidence up to 11.5 mm/yr are obtained for this period and are anthropogenic in origin, being related to earthmoving works. During the Sentinel-1A monitoring period (2015-2016) most of the region showed no deformation, except for some points of unknown origin in the NE sector. A general conclusion is that there is a clear lithological control in the spatial distribution of ground subsidence; all the subsiding areas detected are located where a higher clay content was identified. Although the SE sector of the aquifer had more intense groundwater exploitation, no land subsidence processes were detected, as coarse-grained sediments predominate in the substratum. This research will contribute to the drawing-up of a management plan for the sustainable use of this strategic aquifer, taking into account critical levels of

  19. Guatemela: preliminary zircon ages from central cordillera.

    PubMed

    Gomberg, D N; Banks, P O; McBirney, A R

    1968-10-04

    Concordia resolution of uranium-lead analyses of zircons from rocks of the Guatemalan Cordillera indicates a period of plutonism, and perhaps metamorphism, in late Paleozoic times (345 +/- 20 million years). Gneisses of the Chuacus Series yield an age of 1075 +/- 25 million years which may be either the age of a source terrain for the original sediments, or the age of principal metamorphism. Zircons from a Paleozoic granite intruding the gneisses appear to contain inherited or contaminating material acquired during the process of magma generation or emplacement, or both.

  20. Erosion and isostasy driving the Cordillera Blanca uplift (northern Peru)

    NASA Astrophysics Data System (ADS)

    Margirier, Audrey; Braun, Jean; Audin, Laurence; Robert, Xavier

    2017-04-01

    In mountain ranges, surface uplift is usually assumed to be the result of shortening and crustal thickening. In northern Peru, the Cordillera Blanca hosts to the highest Peruvian summits (>6000 m) and both surface and rock uplift seem closely linked to the Cordillera Blanca normal fault (CBNF) which delimits the western flank of the Cordillera Blanca. Several models have been proposed to explain the presence of this major normal fault in such a compressional setting but both the presence of the CBNF and the Cordillera Blanca recent rapid uplift remain enigmatic. This raises numerous questions about the role of normal faulting in the formation of such high topography at Myrs to kyrs time-scales. Therefore, to understand the nature of the processes driving normal faulting and relief creation in the Cordillera Blanca is a fundamental question. The Cordillera Blanca morphology shows that it has been strongly affected by glacial erosion and, therefore, that a significant mass of rocks has been removed. The impact of erosion and isostasy on the Cordillera Blanca uplift has, however, never been explored. Here, we attempt to evaluate the contribution of erosion and associated flexural rebound to the uplift and exhumation of the Cordillera Blanca using numerical modelling of landscape evolution (FastScape). We performed joint inversions of the present day topography and thermochronological data to provide new independent constraints on model parameters controlling the uplift, erosion and thermal history of the massif: i.e. the erosion efficiency factor, the uplift rate and the temperature gradient. Our results show the strong contribution of erosion and isostasy to the Cordillera Blanca uplift. It indicates that climatic and erosion forcing is at least as important as tectonic forcing in this area. This leads us to propose a new model for the CBNF in which regional surface uplift, fault reactivation and glacial erosion control the landscape evolution and mountain building

  1. Use of Bioassay test for the environmental evaluation of mining residues and their leachates: the singular case of the Portman Bay (SE, Spain)

    NASA Astrophysics Data System (ADS)

    Martínez-Sánchez, Maria Jose; García-Lorenzo, Maria Luz; Pérez-Sirvent, Carmen; Molina, Jose; Tudela, Maria Luz; Hernández-Córdoba, Manuel

    2010-05-01

    The aim of the present study was to evaluate the toxicity of sediments and their pore-water extracts from sites contaminated by mining activities using two assays: bacteria and plants. The acute toxicity in pore-waters was determined using the Microtox® bioassay, which uses the naturally luminescent marine bacterium Vibrio fischeri. Phytotoxicity in soil samples was tested by way of the seed germination and root elongation technique in three plant species, Sorghum saccharatum, Sinapis alba and Lepidium sativum. The aim of applying these assays is to establish a method for evaluating the real risks within a risk analysis process, considering both present and future risks, bearing in mind that the uses to which soil is put (urban, recreational or industrial) may change. In the zone studied, mining activities have led to heavy metal contamination with the risk of runoff and wind dispersion of the contaminated material. For this study, 6 sediment samples were collected from Portman Bay (Murcia, SE Spain). The soil extract was prepared by saturation with distilled water and allowing it to stand for four hours. Then, the soil was subjected to a vacuum pressure to extract the soil solution through filter paper. The Zn and Fe content was determined by flame atomic absorption spectrometry (FAAS). The Pb, Cd and Cu content was determined by electrothermal atomization atomic absorption spectrometry (ETAAS). The As content was analysed by atomic fluorescence spectrometry using an automated continuous flow hydride generation (As-AFS) spectrometer. Total Pb concentration varied from 600 to 2500 ppm, with a mean value of 1200 ppm. The average content of Zn was 5300 ppm. The mean concentration of Cd and Cu was 23 and 59 ppm, respectively. Total As concentrations varied from 180 to 470 ppm, with an average value 280 ppm. Finally, the total Fe content ranged from 37% to 47%, with an average value of 40%. Pore-water samples showed neutral pH values and average electrical

  2. Bioavailability of metals in soils and sedimentes affected by old mining actitvities. The study case of the Portman bay (SE, Spain)

    NASA Astrophysics Data System (ADS)

    Martinez-Sanchez, Maria Jose; Agudo, Ines; Banegas, Ascension; Garcia-Lorenzo, Maria Luz; Gonzalez-Ciudad, Eva; Perez-Espinosa, Victor; Martinez-Lopez, Salvadora; Martinez, Lucia; Perz-Sirvent, Carmen

    2010-05-01

    A study on metal (Zn, Pb, Cd, Cu and As) mobilization and analysis of the health risk represented by ingestion from contaminated sediments in Portman Bay (SE Spain) was carried out. This zone has suffered a great impact from mining activity, since million tons of mine tailings were dumped into the bay for a long period, giving as a result the filling of the bay with them. The long-term deposition of metals in soils and sediments can lead to their accumulation and transport, while their toxicity depends on the mobility and bioavailability of a significant fraction of the metals. The ingestion of contaminated soil particles by grazing animals or young children may well represent a special exposure pathway for Pb, Cd and other hazardous metals. The aim of this study was to determine the bioaccessibility of Zn, Pb, Cd, Cu and As ,and the extent to which bioaccessibility is influenced by mineralogy in materials from this mining site as an indicator of the potential risk that metals pose to both environmental and human health. General analytical determinations (pH, particle size, organic matter, equivalent calcium carbonate content and mineralogical composition) were carried out to characterize the samples. The mineralogical composition was studied by X-ray diffraction (XRD), using a Philips PW3040 diffractometer with Cu-Kα. To determine the total metal content, the samples were digested in a Milestone ETHOS PLUS microwave, Zn, Pb, Cu and Cd contents were determined by electrothermal atomization atomic absorption spectrometry, while As was analysed by HG- AFS using an automated continuous flow hydride generation spectrometer. To assess bioaccessibility, the gastric solution was prepared according to the Standard Operating Procedure (SOP) developed by the Solubility/Bioavailability Research Consortium (SBRC). The mineralogical composition, corresponds to materials which have suffered a supergenic oxidation process which has been influenced by the presence of sea water

  3. Multifunctional greenway approach for landscape planning and reclamation of a post-mining district: Cartagena-La Unión, SE Spain

    NASA Astrophysics Data System (ADS)

    Acosta, Jose A.; Faz, Ángel; Zornoza, Raúl; Martínez-Martínez, Silvia; Kabas, Sebla; Bech, Jaume

    2015-04-01

    Fragmented structures create metaphorical wounds in the landscape altering the ecological and cultural processes associated with it, as it can be seen in many mine areas. Therefore it is advisable to organize the reclamation plan in the beginning of mine operating to provide spatial and functional integration of the landscape based on scientific arguments and with all possible legal and administrative means, which is generally the case of the Strategic Environmental Assessment. However, there are many abandon mine areas where no reclamation plan has been carried out, such as the case of Mining District of Sierra Minera Cartagena-La Unión, SE Spain. In these cases it is vital to respond in a sustainable manner for healing the landscape wounds of post-mining activities. Reclamation activities of a post-mining district includes not only the mine soils also all land uses around them, for this reason on necessary create practical solutions for returning the functions of ecologic and cultural processes of the area. Greenway approach shows the main veins which are crucial for keeping alive and sustaining the mentioned processes of the area. Therefore the main objectives of this study are to 1) develop an integrated local greenway network to be able to preserve significant resources and values of the district, and to 2) develop this greenway network as a part of reclamation process for degraded areas. Landscape assessments revealed the most valuable and potential connectivity resources of the area. These clustering and linear patterns of resource concentrations include mountain range and valleys, natural drainage network, legally protected areas and cultural-historical resources. Conservation areas, cultural-educational resources of post-mining activities and the riverbeds have been the main building stones for the greenway corridor. The multifunctional greenway approach serves as landscape reclamation and planning tool in a degraded area by showing the priority zones for

  4. Coupling data from U-series and 10Be CRN to evaluate soil steady-state in the Betic Cordillera

    NASA Astrophysics Data System (ADS)

    Schoonejans, Jerome; Vanacker, Veerle; Opfergelt, Sophie; Granet, Mathieu; Chabaux, François

    2015-04-01

    The regolith mantel is produced by weathering of bedrock through physical and biochemical processes. At the same time, the upper part of the regolith is eroded by gravity mass movements, water and wind erosion. Feedback's between production and erosion of soil material are important for soil development, and are essential to reach long-term steady-state in soil chemical and physical properties. Nowadays, long-term denudation rates of regolith can be quantified by using in-situ cosmogenic nuclides (CRN). If the soil thickness remains constant over sufficiently long time, soil production rates can be determined. However, the a priori assumption of long-term steady-state can be questionable in highly dynamic environments. In this study, we present analytical data from two independent isotopic techniques, in-situ cosmogenic nuclides and Uranium series disequilibrium. The disequilibrium of Uranium isotopes (238U, 234U, 230Th, 226Ra) is an alternative method that allows assessing soil formation rates through isotopic analysis of weathering products. Nine soil profiles were sampled in three different mountain ranges of the Betic Cordillera (SE Spain): Sierra Estancias, Filabres, Cabrera. All soils overly fractured mica schist and are very thin (< 60cm). In each soil profile, we sampled 4 to 6 depth slices in the soil profile, the soil-bedrock interface and (weathered) bedrock. Three of the nine soil profiles were sampled for U-series isotope measurements at EOST (University of Strasbourg). The surface denudation rates (CRN) are about the same in the Sierra Estancias and Filabres (26 ± 10 mm/ky) and increase up to 103 ± 47 mm/ky in the Sierra Cabrera. The spatial variation in soil denudation rates is in agreement with the variation in catchment-wide denudation rates presented by Bellin et al. (2014) which present the highest rates in the Sierra Cabrera (104-246mm/kyr). Moreover it roughly coincides with the pattern of long-term exhumation of the Betic Cordillera. Results

  5. Evaluation of the Olduvai Sub-Chron in the Orce Ravine (SE Spain), Implications for the Plio-Pleistocene Mammal Biostratigraphy and the Age of Orce Archaeological Sites

    NASA Astrophysics Data System (ADS)

    Gibert, L.; Scott, G. R.; Ferrandez, C.

    2002-12-01

    The 4,000km2 Guadix-Baza basin (Betic ranges, SE Spain) exposes a thick and continuous sequence of Plio-Pleistocene continental deposits, represented by cycles of fluviatile-lacustrine sediments. The basin is rich in fossil micro- and macro-mammal sites, which includes the archaeological sites of Venta Micena (VM), Barranco Leon (BL-5) and Fuentenueva-3 (FN-3), that have produced anthropogenic lithic artifacts and human remains. Studies of the micro-mammal associations in this basin have generated a large body of literature on systematics, biostratigraphy, and Neogene faunal replacements. The well known Barranco de Orce (BO) section in the NE sector of the Baza basin exposes seven fossiliferous layers (O-1 to O-7) with Plio-Pleistocene micro- and macro-mammals. Biostratigraphic and magnetostratigraphic data from the BO and nearby sections have been extensively used to calibrate the late Neogene chronology of Western European mammal biozones. In Barranco de Orce, a previously identified normal event assigned to the 'Olduvai' subchron (C2n) has been used to calibrate the first appearance datum (FAD) of the arvicolid Allophaiomys pliocaenicus and to discuss the use of this species in recognizing the Plio-Pleistocene boundary. The FAD of Mimomys ostramosensis in the BO section has been used to calibrate the boundary of biozones MN17/MmQ1 (latest Neogene of Western Europe). This section has also been used to explore the timing of first human colonization of Europe, owing to the stratigraphic and geographic proximity of the BO section to the major paleontological and archaeological sites. There are numerous weaknesses in the continued use of the BO section as a magnetobiostratigraphically calibrated boundary section, including the scarcity of fossil specimens, landslide repeated stratigraphy, and modern (normal) overprinting of the paleomagnetic record. For example, in the successive published magnetostratigraphical and biostratigraphical interpretations, the faunal

  6. The role of water in the formation of clay-rich layers at the slip surface of slope instabilities (Diezma landslide, SE Spain)

    NASA Astrophysics Data System (ADS)

    Azañón, J. M.; Castro, J.; Ureña, C.; Rodríguez-Peces, M. J.

    2012-04-01

    Slope instabilities with a low basal slope (<15°) are lately researched in order to evaluate triggering and conditioning factors. In these landslides, mechanical properties of the rupture surface are exceptionally low. The increase of the pore pressure has been commonly postulated to explain the drastic reduction of strength properties. Low-permeability layers could be preferred candidates to concentrate the largest increase of pore pressure. These clay layers are usually found in sedimentary sequences and colluvial formations. However, in some landslides around the world, a clay-bearing layer of extraordinary purity, have been detected in the rupture surface. Mechanical properties of this layer are lower than the rest of the sliced mass conditioning the slope stability. In the Diezma landslide (SE Spain), a complex movement affecting an area of 6.2 ha, a centimetre layer of smectite clay (montmorillonite-beidellite) controls the strength properties of the whole sliced mass. The triggering factor of this landslide is linked to the infiltration of water from a karstic aquifer located in the head area. Based on the geophysical surveys performed, we have been able to determine the 3D geometry of the main sliding surface, which was in part known from previous borehole data. Electrical resistivity profiles have also revealed to be an excellent tool to detect the degree of moisture in the marly clay materials of the landslide body. Subterranean water stream produces an active hydrolysis of marls fragment and the follow-up of their argillation, typical of chemical and physical interactions between the slip-zone materials and the slip-zone groundwater, when it was chronically saturated. In this study, thermodynamic stability of clay minerals (smectite and kaolinite) and water chemistry (Ca+2 ions) along the slip surface of the Diezma landslide were evaluated. Calcium hydro-carbonate groundwater, as subterranean water percolating the Diezma landslide, induces the formation

  7. Impact of global change on ground subsidence related to aquifer exploitation. The case of the Vega de Granada aquifer (SE Spain)

    NASA Astrophysics Data System (ADS)

    Pulido-Velazquez, David; María Mateos, Rosa; Rueda, Ramon; Pegalajar-Cuellar, Manuel; Ezquerro, Pablo; Béjar, Marta; Herrera, Gerardo; Collados-Lara, Antonio-Juan

    2017-04-01

    better explains the relationship between subsidence, hydraulic changes and the remaining independent variables. This methodology has been applied to the Vega de Granada aquifer system (Granada, SE Spain). The Vega de Granada detrital aquifer (with an extension of 200 km2) is one of the largest groundwater reservoirs in Andalusia and it is considered as strategic for the economy of this semi-arid region. Ground motion was monitored by exploiting SAR images from ENVISAT (2003-2009), Cosmo-SkyMed (2011-2014) and Sentinel-1A (2015-2016). PSInSAR results show an inelastic deformation in the aquifer and land surface displacements values up to -55 mm. The most widespread land subsidence is detected for the ENVISAT period (2003-2009), which coincided with a dry, long period in the region. The highest recorded data accounts up to 10 mm/yr in surface displacement velocity, which were detected in the central part of the aquifer, where many villages are located. For this period, a good correlation between groundwater level depletion and the augmentation of the subsidence average velocity is obtained, and light hydraulic head changes (< 2 m) have a rapid ground motion response. This research will contribute to assess a sustainable management plan of this vital aquifer, taking into account critical levels of groundwater level depletion to avoid land subsidence on the identified vulnerable areas and during drought critical scenarios. This research has been supported by the CGL2013-48424-C2-2-R (MINECO) project.

  8. Changing environmental conditions during a geomagnetic reversal: Evidence from trace element and isotope variations on Pleistocene flowstone sequences from Cueva Victoria (SE Spain)

    NASA Astrophysics Data System (ADS)

    Mertz-Kraus, R.; Kocot, Y.; Gibert, L.; Scott, G. R.; Jochum, K. P.

    2011-12-01

    The weakening or non-existence of the Earth's magnetic field during a polarity transition is supposed to influence climatic conditions causing variations in, e.g., rainfall, weathering, or the amount of meteoric water infiltrating soils and rocks. Such variations can be monitored by the proxy record (stable and radiogenic isotope or elemental variations) of laminated carbonate sequences precipitated in caves (flowstones). In this study, a multiproxy approach is applied to flowstone samples from Cueva Victoria (SE Spain) recording the Brunhes-Matuyama reversal at 0.78 Ma (Marine Isotope Stage MIS 19) or less likely the lower Jaramillo polarity transition at 1.075 Ma (MIS 31). Cueva Victoria is paleontologically important because of the large number of fossilized fauna found (55 species). The flowstone forms a characteristic layer in the cave system allowing multiple sampling at different locations within the system to test the reproducablity of the analytically derived proxies. Element concentrations were determined on two flowstone samples, using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) along transects covering the geomagnetic change from reverse to normal. Most of the monitored elements show distinctive variations with the highest concentrations in the interval related to the polarity transition: U concentrations are up to factor of 5 higher in the interval of the transition. Increased U concentrations can be explained by (UO2)2+-enriched percolating waters enhancing the weathering during wetter conditions. About four times higher P concentrations indicate changes in vegetation and soil productivity influencing the supply of P to the cave system. Similar concentration maxima are found for the rare earth elements, but also for other elements such as Fe, Na, Al, and Si. Most of these elements are transported bound on colloids and particles. Higher particle supply to the cave environment points to higher infiltration rates caused by

  9. Porphyry deposits of the Canadian Cordillera

    USGS Publications Warehouse

    McMillan, W.J.; Thompson, J.F.H.; Hart, C.J.R.; Johnston, S.T.

    1996-01-01

    Porphyry deposits are intrusion-related, large tonnage low grade mineral deposits with metal assemblages that may include all or some of copper, molybdenum, gold and silver. The genesis of these deposits is related to the emplacement of intermediate to felsic, hypabyssal, generally porphyritic intrusions that are commonly formed at convergent plate margins. Porphyry deposits of the Canadian Cordillera occur in association with two distinctive intrusive suites: calc-alkalic and alkalic. In the Canadian Cordillera, these deposits formed during two separate time periods: Late Triassic to Middle Jurassic (early Mesozoic), and Late Cretaceous to Eocene (Mesozoic-Cenozoic). Deposits of the early Mesozoic period occur in at least three different arc terranes (Wrangellia, Stikinia and Quesnellia) with a single deposit occurring in the oceanic assemblage of the Cache Creek terrane. These terranes were located outboard from continental North America during formation of most of their contained early Mesozoic porphyry deposits. Some of the deposits of this early period may have been emplaced during terrane collisions. Metal assemblages in deposits of the calc-alkalic suite include Mo-Cu (Brenda), Cu-Mo (Highland Valley, Gibraltar), Cu-Mo-Au-Ag (Island Copper, Schaft Creek) and Cu-Au (Kemess, Kerr).The alkalic suite deposits are characterized by a Cu-Au assemblage (Copper Mountain, Afton-Ajax, Mt. Milligan, Mount Polley, Galore Creek). Although silver is recovered from calc-alkalic and alkalic porphyry copper mining operations, silver data are seldom included in the published reserve figures. Those available are in the range of 1-2 grams per tonne (g??t-1). Alkalic suite deposits are restricted to the early Mesozoic and display distinctive petrology, alteration and mineralization that suggest a similar tectonic setting for both Quesnellia and Stikinia in Early Jurassic time. The younger deposits, late Mesozoic to Cenozoic in age, formed in an intracontinental setting, after the

  10. Slope stability of moraines, Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Klimes, J.; Novotny, J.

    2012-12-01

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

  11. The Macael landscape in the context of a possible candidate as Global Heritage Stone Province (Almería, SE of Spain)

    NASA Astrophysics Data System (ADS)

    Navarro Domínguez, Rafael; Pereira Gómez, Dolores; Carrillo, Gloria; Cruz, Anasol

    2017-04-01

    The beginning of the marble extraction activity in the Macael Area (Almería, South of Spain) date back 4000 years ago, and since then, it has been used in several and important monuments, principally, in Spain. The quality of the works carried out is more than proven. During this time, the extraction has alternated periods of activity with others of lesser or none-activity, ruling both the lives of the inhabitants of the region, and its landscape. The most well-known material extracted in the region, with international recognition, is marble "Blanco Macael" (White Macael), traditionally compared with "Carrara marble". But there are other marbles such as "Amarillo Macael", "Gris Macael" or "Anasol", as well as serpentinites that are referred as "Verde Macael" or "Verde Almería". All of them have been employed in many recent important buildings, at national and international level. The problem of this intensive activity through the years, from the point of view of the preservation of the old landscapes, is that the modern quarries have replaced the old ones, leaving few remains of the old quarries. In some cases it is possible to see Muslim vestiges (e.g. "Puntilla"), but this is an exception. Notwithstanding, the landscape of the region has a high value due to the combination of high mountains, high faces with a lot of banks, waste dumps and full restored areas. Nowadays, the surface occupied by mining exploitation, only in the closer area to Macael village, is more 8.5 km2, with more than forty active quarries and many abandoned ones. These features have helped to configure a singular and beautiful landscape, possibly unique in Spain, in relation with an historic mining activity. This is an important added value to the possible candidature of the "Blanco Macael" as a "Global Heritage Stone Resource" and the "Macael Region" as a "Global Heritage Stone Province", mostly if we consider that these designations must take into consideration the social importance of the

  12. A principal component regression model to forecast airborne concentration of Cupressaceae pollen in the city of Granada (SE Spain), during 1995-2006.

    PubMed

    Ocaña-Peinado, Francisco M; Valderrama, Mariano J; Bouzas, Paula R

    2013-05-01

    The problem of developing a 2-week-on ahead forecast of atmospheric cypress pollen levels is tackled in this paper by developing a principal component multiple regression model involving several climatic variables. The efficacy of the proposed model is validated by means of an application to real data of Cupressaceae pollen concentration in the city of Granada (southeast of Spain). The model was applied to data from 11 consecutive years (1995-2005), with 2006 being used to validate the forecasts. Based on the work of different authors, factors as temperature, humidity, hours of sun and wind speed were incorporated in the model. This methodology explains approximately 75-80% of the variability in the airborne Cupressaceae pollen concentration.

  13. Columbus's Spain.

    ERIC Educational Resources Information Center

    Soria, Jose Manuel Nieto

    1991-01-01

    Describes fifteenth-century Spain's tendencies that proved central to the Columbian enterprise: experience as a conquering and colonizing kingdom, interest in Atlantic expansion, and missionary inclination. Argues that Columbus's arrival in Spain came at the perfect time in Spanish history. Stresses Spain's long history of religious war, conquest,…

  14. Early metal pollution in southwestern Europe: the former littoral lagoon of El Almarjal (Cartagena mining district, S.E. Spain).A sedimentary archive more than 8000 years old.

    PubMed

    Manteca, José-Ignacio; Ros-Sala, Milagros; Ramallo-Asensio, Sebastián; Navarro-Hervás, Francisca; Rodríguez-Estrella, Tomás; Cerezo-Andreo, Felipe; Ortiz-Menéndez, José-Eugenio; de-Torres, Trinidad; Martínez-Andreu, Miguel

    2017-04-01

    A borehole drilling campaign has allowed the study of a former littoral lagoon located next to the harbour city of Cartagena in South-East Spain (close to the Sierra de Cartagena polymetallic ore deposits). This lagoon, which developed during the Holocene, was first a shallow sedimentary marine environment and later evolved into a swampy semi-endorheic basin named "Almarjal" (after the Arab term from the fourteenth century). The lagoon eventually dried out and at present forms part of the substratum of the modern sector of the city urban area. The basin representative sediments are sapropelic black silty facies forming a continuous sedimentary archive, accounting for more than 8000 years of depositional phenomena. The geochemical study of these sediments, together with their absolute calibrated dating by (14)C, allows definition of successive stages of mining and metallurgical activities in the area. In turn, this information provides a more comprehensive perspective regarding metal pollution, particularly lead contamination during different periods of the Recent Prehistory and the Classical Age. The results indicate that the beginning of contamination by lead and other heavy metals occurred as early as 4500 years ago, when the Final Chalcolithic period was taking place in the South-East of the Iberian Peninsula. This finding provides further insights regarding the debate on the origins of lead mining and metallurgy in SE Spain.

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

    NASA Astrophysics Data System (ADS)

    McFadden, E. M.; Ramage, J.; Rodbell, D. T.

    2010-10-01

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

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

    NASA Astrophysics Data System (ADS)

    McFadden, E. M.; Ramage, J.; Rodbell, D. T.

    2011-05-01

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

  17. Comparison of water-level, extensometric, DInSAR and simulation data for quantification of subsidence in Murcia City (SE Spain)

    NASA Astrophysics Data System (ADS)

    Tessitore, S.; Fernández-Merodo, J. A.; Herrera, G.; Tomás, R.; Ramondini, M.; Sanabria, M.; Duro, J.; Mulas, J.; Calcaterra, D.

    2016-05-01

    Subsidence due to groundwater overexploitation has been recognized in the metropolitan area of Murcia (25 km2) in south-eastern Spain since the early 1990s. Previous published works have focused their attention on land subsidence that occurred during the drought period between 1995 and 2008. This work first analyzes the groundwater recovery that has occurred since 2008 and then determines the kind of associated ground deformation detected by the new extensometric data. Subsequently, subsidence time series are computed on 24 geotechnical boreholes scattered throughout the study area by means of a hydro-mechanical finite element code and a linear-elastic constitutive law. A spatio-temporal interpolation of the numerically modeled surface displacements is performed over the whole domain and compared with extensometers and DInSAR-derived displacement maps in two different periods: the drought period from 2004 to 2008, and the recovery period from 2008 to 2012. In spite of the limited information on the geomechanical parameters characterizing the modelled geological formations, the proposed approach is able to discriminate areas where the soils have an elastic behavior (small differences in the comparisons) or an elasto-plastic behavior (large differences in the comparisons). This zonation enhances the understanding of the subsidence phenomenon in Murcia City and could prevent, from a quantitatively point of view, future severe subsidence due to aquifer overexploitation.

  18. Mud volcanism and authigenic carbonates related to methane-rich fluids migration in the Tortonian-Messinian marls of the Huercal Overa basin (S.E. Spain)

    NASA Astrophysics Data System (ADS)

    Pierre, Catherine; Blanc-Valleron, Marie-Madeleine; Rouchy, Jean-Marie

    2017-04-01

    Methane-rich fluids that are generated at depth in organic-rich deposits migrate within the sediments to the seafloor where they are expelled to form mud volcanoes or pockmarks. These migrating fluids are generally involved in diagenetic processes as authigenic carbonate formation that is mediated by microbial activity and they may participate to gas hydrate formation. These features are well-known in the present-day continental margins but their fossil records are relatively scarce. In the Huercal Overa basin (South East Spain), there are chaotic to roughly layered structures intruding the Tortonian-Messinian marls that are interpreted as due to mud volcanism. Moreover, the surrounding marls contain abundant authigenic dolomite nodules. The oxygen and carbon isotopic compositions of these dolomites exhibit wide ranges (-1.4 < δ18O <+3.9 ; -35.5 < δ13C <+5.1). They indicate that authigenic carbonate precipitation occurred within the marly sediments due to circulation of deep fluids that might be relatively warm as shown by the low δ18O values and where anaerobic oxidation of methane (low δ13C values) and methanogenesis (high δ13C values) were active. These two features, methane derived authigenic dolomites and mud volcanism, are testifying of the intense methane-rich fluid migration in the marly deposits of the western Mediterranean basins during the late Neogene, which was the time of major paleoenvironmental changes in the Mediterranean sea climaxing during the Messinian salinity crisis.

  19. Analysis of meteorological droughts and dry spells in semiarid regions: a comparative analysis of probability distribution functions in the Segura Basin (SE Spain)

    NASA Astrophysics Data System (ADS)

    Pérez-Sánchez, Julio; Senent-Aparicio, Javier

    2017-08-01

    Dry spells are an essential concept of drought climatology that clearly defines the semiarid Mediterranean environment and whose consequences are a defining feature for an ecosystem, so vulnerable with regard to water. The present study was conducted to characterize rainfall drought in the Segura River basin located in eastern Spain, marked by the self seasonal nature of these latitudes. A daily precipitation set has been utilized for 29 weather stations during a period of 20 years (1993-2013). Furthermore, four sets of dry spell length (complete series, monthly maximum, seasonal maximum, and annual maximum) are used and simulated for all the weather stations with the following probability distribution functions: Burr, Dagum, error, generalized extreme value, generalized logistic, generalized Pareto, Gumbel Max, inverse Gaussian, Johnson SB, Log-Logistic, Log-Pearson 3, Triangular, Weibull, and Wakeby. Only the series of annual maximum spell offer a good adjustment for all the weather stations, thereby gaining the role of Wakeby as the best result, with a p value means of 0.9424 for the Kolmogorov-Smirnov test (0.2 significance level). Probability of dry spell duration for return periods of 2, 5, 10, and 25 years maps reveal the northeast-southeast gradient, increasing periods with annual rainfall of less than 0.1 mm in the eastern third of the basin, in the proximity of the Mediterranean slope.

  20. Heavy metal accumulation and tolerance in plants from mine tailings of the semiarid Cartagena-La Unión mining district (SE Spain).

    PubMed

    Conesa, Héctor M; Faz, Angel; Arnaldos, Raquel

    2006-07-31

    Mine tailings are a characteristic of landscapes where mineral extraction has occurred. These tailings usually contain high heavy metal concentrations and have low fertility. In arid and semiarid zones, erosion may be an additional problem. The removal of these tailings is often impractical due to their large volumes. Therefore, a need exists to develop in situ low cost technologies to effect surface stabilization. The use of vegetation can be an attractive option, since there are some native plant species that can colonize parts of these polluted sites unaided. Some edaphic factors were investigated, including heavy metal concentrations, in three mine tailings from a semiarid mining zone in Southeast Spain. High total metal concentrations were found: 5000-8000 mg/kg for lead and 7600-12300 mg/kg for zinc. Two of these mine tailings had pH values between 6 and 7, while the other was acidic, with a pH of 2.5. Metal solubility was pH dependent, with more than 10% of the total zinc soluble in the acid substrate and less than 1% in the neutral substrates. The metal concentrations (copper, lead and zinc) in shoots of native vegetation colonizing in these sites were studied. No species of hyperaccumulators were found. The highest concentrations were found in Zygophyllum fabago, with 530 mg/kg zinc, Helichrysum decumbens with 390 mg/kg lead, and Tamarix sp. with 11 mg/kg copper. An analysis of the rhizospheric soil of these plants indicated that Lygeum spartum grew in pH 3 soil and had low metal concentration in shoots (40 mg/kg zinc and 41 mg/kg lead).

  1. Uplift of the Eastern Cordillera, Colombia

    NASA Astrophysics Data System (ADS)

    Siravo, Gaia; Faccenna, Claudio; Giuditta Fellin, Maria; Molin, Paola; Bayona, German; Giachetta, Emanuele

    2017-04-01

    The Eastern Cordillera (EC) of Colombia is a double-vergent thrust and fold belt formed during the Cenozoic by the inversion of a Mesozoic rift. It is located 400 km far from the trench where the Nazca slab subducts below the South American plate. Tomography and seismicity highlight the presence of a flat slab subduction north of 5° N. Our goal is to explore the relation between surface and crustal processes in the topography growth of the EC north of 6° N. To reach this aim we integrate data derived from the fluvial network analysis with long-term erosion data derived from thermochronology. The northern EC is an asymmetric chain with a gentle flank on the western side and steep flank to the east. The two sides are separated by the maximum elevation of 5000 m reached at the Cocuy Sierra. Here the EC has the widest width ( 200 km) and changes northward to the Santander Massif Range. We obtained new low-T (U-Th)/He ages on zircons (ZHe) and apatites (AHe) from samples collected along two transects. Our ages combined with previous data indicate that along both transects exhumation occurred from shallow burial depths (≤ 6-8 km) during the Oligo-Miocene and locally continued until the Pliocene. Along the transect across the central part of the EC up to the Cocuy Sierra, the youngest Pliocene ages (AHe) are located at the highest elevations above 4000 m. Along the second transect the youngest ages are found close to and east of a main strike-slip structure (Bucaramanga fault). This fault has a significant dip-slip component evidenced by an offset of about 10 Ma among the AHe ages across the fault. The main rivers draining the northern EC flow parallel to the main tectonic structures and locally cut across them. The analysis of river longitudinal profiles reveal transient features such as knickpoint not related to lithological or structural contrast. Channel slope and chi analysis suggest a river capture event possibly influenced by the crustal structures. Wind gaps

  2. Latest extension of the Laujar fault in a convergence setting (Sierra Nevada, Betic Cordillera)

    NASA Astrophysics Data System (ADS)

    Martínez-Martos, Manuel; Galindo-Zaldívar, Jesus; Sanz de Galdeano, Carlos; García-Tortosa, Francisco Juan; Martínez-Moreno, Francisco José; Ruano, Patricia; González-Castillo, Lourdes; Azañón, José Miguel

    2017-02-01

    The present-day relief of the Betic Cordillera formed since the Late Miocene through the regional N-S to NW-SE Africa-Eurasia convergence that developed large folds. The Laujar Fault Zone is a south-dipping E-W oriented structure located at the northern boundary of the Alpujarran Corridor Neogene intramontane basin, which separates Sierra Nevada and Sierra de Gador antiforms, in the Internal Zones of the Betic Cordillera. The fault zone acted in a first stage as a dextral strike-slip fault. Currently it moves as a normal fault evidenced by striated calcretes, also in agreement with regional continuous GPS (CGPS) data that support the hypothesis of an active N-S extension in the fault area. In order to analyse the deep geometry of the Laujar Fault Zone, we combined several geophysical techniques (gravity, magnetic, electric resistivity tomography and audio-magnetotelluric data) with field geological observations. Fault surfaces seem to join at a southward-dipping shallow detachment level, including faults covered by the sedimentary infill. The fault zone was developed in a previously weakened area by wrench faults parallel to the Alpujarran Corridor. The recent normal activity of this fault zone may be a consequence of a change in the Africa-Eurasia convergence orientation, which implies a decrease in the N-S compression component. This structure along the southern limb of Sierra Nevada antiform evidences the gravitational collapse of previously thickened crust in a regional compressional context simultaneous to metamorphic core uplift.

  3. Superposition of tectonic structures leading elongated intramontane basin: the Alhabia basin (Internal Zones, Betic Cordillera)

    NASA Astrophysics Data System (ADS)

    Martínez-Martos, Manuel; Galindo-Zaldivar, Jesús; Martínez-Moreno, Francisco José; Calvo-Rayo, Raquel; Sanz de Galdeano, Carlos

    2017-01-01

    The relief of the Betic Cordillera was formed since the late Serravallian inducing the development of intramontane basins. The Alhabia basin, situated in the central part of the Internal Zones, is located at the intersection of the Alpujarran Corridor, the Tabernas basin, both trending E-W, and the NW-SE oriented Gádor-Almería basin. The geometry of the basin has been constrained by new gravity data. The basin is limited to the North by the Sierra de Filabres and Sierra Nevada antiforms that started to develop in Serravallian times under N-S shortening and to the south by Sierra Alhamilla and Sierra de Gádor antiforms. Plate convergence in the region rotated counter-clockwise in Tortonian times favouring the formation of E-W dextral faults. In this setting, NE-SW extension, orthogonal to the shortening direction, was accommodated by normal faults on the SW edge of Sierra Alhamilla. The Alhabia basin shows a cross-shaped depocentre in the zone of synform and fault intersection. This field example serves to constrain recent counter-clockwise stress rotation during the latest stages of Neogene-Quaternary basin evolution in the Betic Cordillera Internal Zones and underlines the importance of studying the basins' deep structure and its relation with the tectonic structures interactions.

  4. A multidisciplinary study for mining landscape reclamation: A study case on two tailing ponds in the Region of Murcia (SE Spain)

    NASA Astrophysics Data System (ADS)

    Martínez-Pagán, P.; Faz, A.; Acosta, J. A.; Carmona, D. M.; Martínez-Martínez, S.

    The aim of this work was to evaluate the mobility of Pb, Cu, Zn and Cd in two tailing ponds (Brunita and San Cristobal) from mine activity in the Southeast of Spain before applying reclamation measures for reducing the risk for human and environment. To achieve this objective, five profiles of electrical resistivity imaging (ERI) in Brunita, three profiles in San Cristobal, a drill-hole in each pond and undisturbed columns amended with marble waste for leaching experiments were taken. Results showed that all layers of the two ponds exceed the maximum Pb and Zn concentrations allowed by the selected European legislations. In both ponds, the mixture of tailings with natural soil is the main process involved in soil pollution under the ponds. However, due to high pH in the substrate the metals are precipitated and their solubility reduced, therefore there is not a risk of leaching to groundwater. At Brunita tailing pond electrical resistivity sections displayed some lower electrical resistivity region into the bedrock which has been described as some fault occurrence due to breaking events suffered by the tailing pond. At San Cristobal tailing pond geochemical results were consistent with data obtained by the electrical resistivity imaging (ERI) method where no evidence of faults or cracks into the bedrock and the ponds were observed. Therefore, no preferential pathways of acid mine drainages containing heavy metals were reported. Leaching experiments indicated that, after 11 weeks of leaching, amended and control columns showed comparable values of pH (∼2.3) and similar trends for Cu, Cd and Zn, with a very drastic decrease up to week 3 and thereafter the tendency was to reach near steady-state conditions. In contrast, the evolution of Pb showed that marble amended reduces significantly its concentration over time compared with the control. In accordance with the results, future reclamation action should be based on the reduction of heavy metal mobility by means of

  5. Groundwater temperature patterns in the freshwater-saltwater contact zone in coastal aquifers. The Motril-Salobreña Aquifer (SE Spain)

    NASA Astrophysics Data System (ADS)

    Calvache, Maria Luisa; Duque, Carlos; Lopez-Chicano, Manuel; Martin-Rosales, Wenceslao; Sanchez-Ubeda, Juan Pedro

    2013-04-01

    The groundwater temperature in the freshwater-saltwater contact zones shows a characteristic pattern completely different from that monitored in other parts of the coastal aquifers. The temperature-depth profiles of seven wells in the Motril-Salobreña aquifer (southern Spain) were used as a basis for a comparative analysis involving various parameters to determine their relations and factors influencing the different trends. The temperature profiles show a shallow belt of variable temperature (up to 5 °C) that can reach depths in the groundwater ranging from 15 m to 45 m. There is an influence of ambient temperature on all the profiles, with a lag time of two to five months. Furthermore, there is a clear influence of the Guadalfeo River (the main source of recharge to the aquifer) reflected in a decrease in temperature coinciding with peak flow rates in the river and the highest water tables in the aquifer during the springtime when the river flow derives mainly from snowmelt from Sierra Nevada. In the autumn, there are secondary peaks in river flow rates due to rainfall, and the river temperature is higher than in spring. In this case, the groundwater temperature rises. This influence fades with distance from the river. In the summer, when the river is dry, the temperature profiles are straight, with no effect on groundwater temperature. Three of the wells, the closest ones to the coastal line, are exception. However, as there is no clear coincidence between temperature valleys and peaks in the river flow rate, making it difficult to establish a relation between the groundwater temperatures and the river recharge in these two cases. Instead, we must recur to a discharge-zone flow pattern, typical of the freshwater-saltwater contact in a coastal aquifer (Glover, 1959), that generates vertical upward fluxes due to the density contrast when is reaching the saline wedge. In this case is even more pronounced due to the fact that the Motril-Salobreña aquifer has

  6. Background and baseline values for thallium and antimony in soils from Murcia Region (SE, Spain) and their relationship with mineralogical composition

    NASA Astrophysics Data System (ADS)

    Martínez-Sánchez, M. J.; Pérez-Sirvent, C.; García-Lorenzo, M. L.; Tudela, M. L.; Molina, J.; Bech, J.

    2009-04-01

    Thallium minerals are very rare and are formed exclusively during the epithermal stage of hydrothermal activity or under supergene conditions. Examples of these minerals include lorandite (TlAsS2), picotpaulite (TlFe2S3) and vrbaite (Hg3Tl4As8Sb2S20). Thallium is extremely toxic, but little studied, affecting the central nervous system. Antimony is a low-abundance chalcophile element forming several rather rare minerals including stibnite (Sb2S3), valentinite (Sb2O3) and kermesite (Sb2S2O), but is more usually present at trace levels in minerals such as ilmenite, Mg-olivine, galena, sphalerite and pyrite. Antimony has no known function in living organisms and high concentrations of Sb are highly toxic. The objective of this study was to determine the thallium and selenium background and baseline levels in soils from the Region of Murcia (Southeast, Spain) and to study the possible relationship between mineralogical composition, soil properties and antimony and thallium concentration. Sampling sites corresponded to areas subjected to high and similar agricultural activity or soils with natural vegetation, which correspond to abandoned agricultural areas. A total of 490 samples were collected, and the mineralogical composition and thallium and antimony content were determined. Samples were analysed for antimony content by atomic fluorescence spectrometry (AFS) and by inductively coupled plasma spectrometry (ICP-MS) for thallium content. The results showed that the concentration of target metals was correlated with the mineralogical composition. Thus, thallium and antimony level was positively correlated with the phylosilicate content and with amphibole, quartz and calcite content. In addition, both metals were positively correlated. In summary, the background level for thallium and antimony, showed as the median, was 0.20 mg kg-1 and 1.06 mg kg-1 respectively. Baseline level, showed as mean+ 2*Std. deviation, was 0.64 mg kg-1 for thallium and 3.12 mg kg-1 for

  7. On the physical- and socioeconomic aspects of land degradation in the Guadalentin basin (SE-Spain): Towards comprehensive understanding for effective remediation

    NASA Astrophysics Data System (ADS)

    de Vente, J.; Solé-Benet, A.; Boix-Fayos, C.; Nainggolan, D.

    2009-04-01

    During the last two decades, the Guadalentin basin in south-eastern Spain has been the study area for many national- and international studies dealing with land degradation and desertification. One of the reasons for such a broad interest in the Guadalentin basin is that land degradation is generally considered severe in large parts of the basin due to a combination of the Mediterranean climate characterised by dry summers followed by intense autumn rainfall, steep topography that marks most parts of the landscape, and fragile soils on erodible lithologies. The main types of degradation are due to soil erosion, soil surface crusting, aridity, soil organic matter decline and salinisation. Moreover, triggered by various political and socioeconomic drivers, important land use and management changes have taken place over the last centuries, which have formed an important driver for further land degradation. Examples of such changes are large-scale land abandonment, a shift from dryland cereals production to large almond plantations, large scale land levelling for irrigated horticulture and urban expansions, and several types of agricultural subsidies. Numerous publications have been produced based on works done to address land degradation in the Guadalentin. However, until now there is no concise and integrated overview of what has been done and what is still missing regarding the study of the physical- and socioeconomic aspects of land degradation and conservation. This is in fact crucial to assist policy makers in making decisions that would effectively navigate land management in the area to a sustainable way. Here, we aim to provide such an overview by listing and discussing the main studies performed in this area, and by providing an integrated synthesis of the main physical- and socioeconomic factors identified in these studies as being responsible for land degradation, with a focus on feasible soil conservation strategies. In overall, there has been a strong

  8. Dual origins of lode gold deposits in the Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Nesbitt, Bruce E.; Murowchick, James B.; Muehlenbachs, Karlis

    1986-06-01

    From Late Jurassic to late Tertiary time, two geologically, geochemically, and genetically distinct gold mineralization processes were active in the Canadian Cordillera. One group of deposits can be characterized as epithermal because of its association with intermediate to felsic volcanics, regional caldera structures, low pH alteration zones, low Au/Ag values, and quartz-chalcedony-barite-fluorite gangue. The second group of deposits is mesothermal in character and has strong similarities to the Mother Lode deposits of California, being associated with transcurrent faults, intermediate pH alteration zones, and quartz ± carbonate, albite, mariposite, pyrite, arsenopyrite, scheelite gangue. Compared to epithermal deposits, mesothermal deposits have higher As, W, and Au/Ag values, higher CO2 content in fluid inclusions, and δ18O values of ore-forming fluids of +3‰ to +10‰ vs. -14‰ to -7‰ for epithermal deposits. Like the gold deposits in Nevada and Colorado, epithermal mineralization in the Canadian Cordillera formed from the shallow circulation of meteoric water in subaerial, intermediate to felsic volcanic complexes. In contrast, mesothermal gold deposits throughout the North American Cordillera are shown to be the product of deep circulation and evolution of meteoric water in structures associated with major, transcurrent fault zones. Similarities between Archean lode gold deposits and mesothermal deposits of the Cordillera suggest that Archean lode deposits may have been produced by processes similar to those involved in the formation of Cordilleran mesothermal deposits.

  9. Geochronology of Quaternary glaciations from the tropical Cordillera Huayhuash, Peru

    NASA Astrophysics Data System (ADS)

    Hall, Sarah R.; Farber, Daniel L.; Ramage, Joan M.; Rodbell, Donald T.; Finkel, Robert C.; Smith, Jacqueline A.; Mark, Bryan G.; Kassel, Christopher

    2009-12-01

    The Cordillera Huayhuash in the central Peruvian Andes (10.3°S, 76.9°W) is an ideal mountain range in which to study regional climate through variations in paleoglacier extents. The range trends nearly north-south with modern glaciers confined to peaks >4800 m a.s.l. Geomorphology and geochronology in the nearby Cordillera Blanca and Junin Plain reveal that the Peruvian Andes preserve a detailed record of tropical glaciation. Here, we use ASTER imagery, aerial photographs, and GPS to map and date glacial features in both the western and eastern drainages of the Cordillera Huayhuash. We have used in situ produced cosmogenic 10Be concentrations in quartz bearing erratics on moraine crests and ice-polished bedrock surfaces to develop an exposure age chronology for Pleistocene glaciation within the range. We have also collected sediment cores from moraine-dammed lakes and bogs to provide limiting 14C ages for glacial deposits. In contrast to the ranges to the north and south, most glacial features within the Cordillera Huayhuash are Lateglacial in age, however we have identified features with ages that span ˜0.2 to ˜38 ka with moraine sets marking the onset of glacier retreat at ˜0.3 ka, ˜9-10 ka, ˜13-14 ka, ˜20-22 ka, and >26 ka. The range displays a pronounced east-west variation in maximum down-valley distance from the headwall of moraine crests with considerably longer paleoglaciers in the eastern drainages. Importantly, Lateglacial paleoglaciers reached a terminal elevation of ˜4000 m a.s.l. on both sides of the Cordillera Huayhuash; suggesting that temperature may have been a dominant factor in controlling the maximum glacier extent. We suggest that valley morphology, specifically valley slope, strongly influences down-valley distance to the maximum glacier extent and potential for moraine preservation. While regionally there is an extensive record of older (>50 ka) advances to the north (Cordillera Blanca) and to the south (Junin region), the apparent

  10. On the ecological context of the earliest human settlements in Europe: Resource availability and competition intensity in the carnivore guild of Barranco León-D and Fuente Nueva-3 (Orce, Baza Basin, SE Spain)

    NASA Astrophysics Data System (ADS)

    Rodríguez-Gómez, Guillermo; Palmqvist, Paul; Rodríguez, Jesús; Mateos, Ana; Martín-González, Jesús A.; Espigares, M. Patrocinio; Ros-Montoya, Sergio; Martínez-Navarro, Bienvenido

    2016-07-01

    With an age of ∼1.4 Ma, the Early Pleistocene archaeopaleontological sites of Barranco León and Fuente Nueva-3 (Orce, Baza Basin, SE Spain) provide the oldest evidence on human presence in Western Europe, including the finding of a deciduous tooth of Homo sp., huge lithic assemblages of Oldowan tradition and abundant cut-marks on large mammal bones. Here we use a mathematical approach based on Leslie matrices to quantify for the large mammal species preserved at the sites the biomass of primary consumers available, the distribution of meat resources among the secondary consumers and the competition intensity within the carnivore guild. The results obtained show a community of large mammals with a high diversity of secondary consumers that would satisfy slightly less than half of their dietary requirements under optimal ecological conditions. In the case of Homo sp., and considering that flesh resources were obtained through the scavenging of ungulate carcasses, the model indicates that the ecosystems of the basin could hold 10-14 individuals per 100 km2 during a year, a value that is close to the mean population density of recent hunter-gatherers. These density estimates decrease slightly when a mixed hunting-scavenging strategy is considered and even more in the case of a strict hunting behavior. In addition, the value of the species competition index obtained for Homo sp. is among the lowest of the carnivore guild. These results suggest that the hominin populations that inhabited Southeast Spain during the Early Pleistocene behaved more as opportunistic scavengers than as active predators.

  11. Mountain front migration and drainage captures related to fault segment linkage and growth: The Polopos transpressive fault zone (southeastern Betics, SE Spain)

    NASA Astrophysics Data System (ADS)

    Giaconia, Flavio; Booth-Rea, Guillermo; Martínez-Martínez, José Miguel; Azañón, José Miguel; Pérez-Romero, Joaquín; Villegas, Irene

    2013-01-01

    The Polopos E-W- to ESE-WNW-oriented dextral-reverse fault zone is formed by the North Alhamilla reverse fault and the North and South Gafarillos dextral faults. It is a conjugate fault system of the sinistral NNE-SSW Palomares fault zone, active from the late most Tortonian (≈7 Ma) up to the late Pleistocene (≥70 ky) in the southeastern Betics. The helicoidal geometry of the fault zone permits to shift SE-directed movement along the South Cabrera reverse fault to NW-directed shortening along the North Alhamilla reverse fault via vertical Gafarillos fault segments, in between. Since the Messinian, fault activity migrated southwards forming the South Gafarillos fault and displacing the active fault-related mountain-front from the north to the south of Sierra de Polopos; whilst recent activity of the North Alhamilla reverse fault migrated westwards. The Polopos fault zone determined the differential uplift between the Sierra Alhamilla and the Tabernas-Sorbas basin promoting the middle Pleistocene capture that occurred in the southern margin of the Sorbas basin. Continued tectonic uplift of the Sierra Alhamilla-Polopos and Cabrera anticlinoria and local subsidence associated to the Palomares fault zone in the Vera basin promoted the headward erosion of the Aguas river drainage that captured the Sorbas basin during the late Pleistocene.

  12. North American Cordillera-wide lower crustal channel flow

    NASA Astrophysics Data System (ADS)

    Hyndman, R. D.

    2016-12-01

    It has been recognized for some time that lower crust flow is occurring in the thick crust high plateaux of Tibet and the high Andes, as well as in the special local area of the currently extending US Basin and Range. However, USArray and other recent data result in the surprising conclusion that lower crustal channel flow occurs in most of the North America Cordillera; the Basin and Range is not unique. I first summarize the evidence for flow and then the evidence for high temperatures in the lower crust such that that flow is to be expected. The principal evidence for flow comes from seismic structure data that show the Moho is remarkably flat and has constant thickness, 33±3 km, in most of the Cordillera from Mexico to Alaska. The flat Moho is evident over lateral distances of 10's of km from multichannel seismic reflection, and 100's of km from seismic refraction, seismic tomography, and receiver functions, in spite of a complex history of normal faulting, shortening deformation, and terrane accretion,. I argue that the constant crustal thickness and flat Moho result from lower crust flow associated with Cordillera-wide high temperatures. The backarc Moho can be viewed as almost `liquid' lower crust over low-viscosity upper mantle. The Moho boundary relaxes to a nearly-horizontal gravitational equipotential over a few 10s of m.y. Significant mountain belt elevations within the Cordillera backarc last only a few 10s m.y. unless maintained by ongoing shortening. Thermal constraints are now adequate to show that most of the Cordillera is uniformly hot in common with other backarcs, 800-850°C at the Moho, from heat flow measurements, upper mantle temperature-dependent seismic velocities, mantle xenoliths, receiver function lithosphere thicknesses, and thermal elevations. Other indicators of lower crust flow are, common lower crust horizontal seismic reflectors that may result from shear, outcrops of former lower crust that show past horizontal shear at lower

  13. Integrating soil water and tracer balances, numerical modelling and GIS tools to estimate regional groundwater recharge: Application to the Alcadozo Aquifer System (SE Spain).

    PubMed

    Hornero, Jorge; Manzano, Marisol; Ortega, Lucía; Custodio, Emilio

    2016-10-15

    Groundwater recharge is one of the key variables for aquifer management and also one of the most difficult to be evaluated with acceptable accuracy. This is especially relevant in semiarid areas, where the processes involved in recharge are widely variable. Uncertainty should be estimated to know how reliable recharge estimations are. Groundwater recharge has been calculated in the Alcadozo Aquifer System, under steady state conditions, at regional (aquifer) and sub-regional (spring catchment) scales applying different methods. The regional distribution of long-term average recharge values has been estimated with the chloride mass balance method using data from four rain stations and 40 groundwater samples covering almost the whole aquifer surface. A remarkable spatial variability has been found. Average annual recharge rates ranges from 20 to 243mmyear(-1) across the aquifer, with an estimated coefficient of variation between 0.16 and 0.38. The average recharge/precipitation ratio decreases from 34% in the NW to 6% in the SE, following the topographic slope. At spring-catchment scale, recharge has been estimated by modelling the soil water balance with the code Visual Balan 2.0. The results, calibrated with discharge data of the two main springs Liétor and Ayna, are 35.5 and 50mmyear(-1) respectively, with estimated coefficients of variation of 0.49 and 0.36. A sensitivity analysis showed that soil parameters influence the most the uncertainty of recharge estimations. Recharge values estimated with both methods and at two temporal and spatial scales are consistent, considering the regional variability obtained with the chloride method and the respective confidence intervals. Evaluating the uncertainties of each method eased to compare their relative results and to check their agreement, which provided confidence to the values obtained. Thus, the use of independent methods together with their uncertainties is strongly recommended to constrain the magnitude and to

  14. Variations of the Crustal Structure in the Rif Cordillera, N-Morocco from Wide-Angle Seismic Data

    NASA Astrophysics Data System (ADS)

    Gallart, J.; Gil, A.; Diaz, J.; Carbonell, R.; Harnafi, M.; Levander, A.; Palomeras, I.; Cordoba, D.

    2012-12-01

    The Rif Cordillera, located in North Morocco forms, together with the Betic Cordillera, the Gibraltar Arc around the Alboran Sea. This asymmetric curved mountain belt originated during a Miocene continent-continent collision as a result of the westward motion of the Alboran domain between northwest Africa and Iberia. The complexity of the area favored the proposition of diverse tectonic models, poorly constrained by available geophysical data. Previous numerical models that integrate both elevation, geoid and gravity anomalies assuming local isostasy suggest a poorly marked orogenic root beneath the Rif Cordillera, whereas a recent receiver function study from Topo-Iberia project reveals large variations of at least 10 km in crustal thicknesses under northern Morocco, similarly to values obtained in station terms from a Pn tomography. In order to constrain the seismic velocity structure of the Rif Cordillera and to delineate the Moho topography, in October 2011, within the Spanish project RIFSIS complemented by the US-PICASSO one, wide-angle reflection and refraction seismic data were acquired for the first time along two 330 km-length profiles, oriented respectively N-S and E-W. The N-S line was extended northwards by a 70 km long segment in Spain, along the Betics. Southwards, this profile connects with the one recorded in 2010 across the Atlas Mountains (SIMA project), hence delineating a 700 km-long wide-angle seismic transect across the Betic-Rif-Atlas systems. Seismic energy released at 5 shot points was generated by the detonation of 1 TN of explosives and was recorded by ~ 900 Texans stations from the IRIS-PASCAL pool, with an average station spacing of about 750 m. Crustal phases Pg, PcP and PiP and Moho reflected PmP phases are clearly identified in the processed datasets. Preliminary analyses by forward modeling already reveal the existence of major variations in crustal thicknesses, especially along the E-W profile that documents differences of about 20

  15. Lower-crustal flow and detachment in the North American Cordillera: a consequence of Cordillera-wide high temperatures

    NASA Astrophysics Data System (ADS)

    Hyndman, R. D.

    2017-06-01

    In this paper, I make the case for widespread lower-crustal detachment and flow in the North American Cordillera. An indicator that geologically recent flow has occurred comes from seismic structure data showing the crust in most of the Cordillera from Mexico to Alaska is uniformly thin, 33 ± 3 km, with a remarkably flat Moho. The flat Moho is in spite of extensive normal faulting and shortening that might be expected to deform the Moho. It has been concluded previously that the high topographic elevations are due to thermal expansion from Cordillera-wide high temperatures compared to stable areas, not due to a crustal root. I argue that the constant crustal thickness and flat Moho also are a consequence of temperatures sufficiently hot for flow in the lower crust. Lower-crust detachment and flow has previously been inferred for Tibet and the high Andes where the crust is thick such that unusually high temperatures are expected. More surprising is the similar conclusion for the Basin and Range of western USA where the crust is thin, but high temperatures have been inferred to result from current extension. There are now adequate data to conclude the Basin and Range is not unique in crustal thickness or in temperature. The crust in most of the Cordillera is similarly hot in common with many other backarcs. Five thermal constraints are discussed that indicate that for most of the Cordillera, the temperature at the Moho is 800-850 °C compared to 400-450 °C in stable areas. At these temperatures, the effective viscosity is low enough for flow near the base of the crust. The backarc Moho may be viewed as a boundary between almost 'liquid' lower crust over a higher viscosity, but still weak upper mantle. The temperatures are sufficiently high for the Moho to relax to a nearly horizontal gravitational equipotential over a few tens of millions of years. The inference of a weak lower crust also suggests that topography over horizontal scales of over 100 km must be short

  16. Guadiana fault: magnetic and gravity constraints related with the Monchique Alkaline Complex structure (Betic Cordillera foreland)

    NASA Astrophysics Data System (ADS)

    González-Castillo, Lourdes; Galindo-Zaldívar, Jesús; Ruiz-Constán, Ana; Pedrera, Antonio

    2014-05-01

    Geophysical data are essential to reveal the main crustal deep structures in areas where geological surface observations do not provide enough detailed data. Magnetic anomalies studies help us to constrain the structure of intermediate and basic igneous rocks. Magnetic and gravity surveys have been combined to determine the geometry, position and properties of intermediate igneous intrusive bodies responsible of the magnetic anomalies in the western area of the Betic Cordillera foreland. Furthermore, crustal structure has been characterized revealing the presence of a blind fault: The Guadiana fault. The aeromagnetic data reveal that the southwestern Iberian Peninsula is characterized by an elongated E-W dipole extending 200 km towards the Betic Cordillera external zones. The anomaly is related to the outcropping Monchique Alkaline Complex, characterized by rocks of moderate magnetic susceptibility (0.029 SI) intruding into the metapelitic host rock of the South Portuguese Zone. In this region, new total field magnetic data has been acquired with a GSM 8 proton precession magnetometer with an accuracy of 1 nT at a mean height of 2 m above the topography. Susceptibility measurements were done with an Exploranium KT-9 kappameter. Combined analysis of aeromagnetic and field magnetic anomalies serves to constrain the depth and geometry of this laccolith. Toward the east, the magnetic dipole has a 60 km long N-S sharp step that coincides with the southern part of the Guadiana River (Spain-Portugal southernmost border). In addition, gravity measurements were performed simultaneously with the magnetic data acquisition using a Scintrex Autograv CG-5 gravity meter whose maximum accuracy is 0.001 mGal. This data support the presence of this major discontinuity in the elongated anomalous body, with an E downthrown block, interpreted as the offset produced by a deep N-S crustal fault - The Guadiana Fault. Therefore, the Guadiana River has three long linear segments near its

  17. The Agost Basin (Betic Cordillera, Alicante province, Spain): a pull-apart basin involving salt tectonics

    NASA Astrophysics Data System (ADS)

    Martín-Martín, Manuel; Estévez, Antonio; Martín-Rojas, Ivan; Guerrera, Francesco; Alcalá, Francisco J.; Serrano, Francisco; Tramontana, Mario

    2017-08-01

    The Agost Basin is characterized by a Miocene-Quaternary shallow marine and continental infilling controlled by the evolution of several curvilinear faults involving salt tectonics derived from Triassic rocks. From the Serravallian on, the area experienced a horizontal maximum compression with a rotation of the maximum stress axis from E-W to N-S. The resulting deformation gave rise to a strike-slip fault whose evolution is characterized progressively by three stages: (1) stepover/releasing bend with a dextral motion of blocks; (2) very close to pure horizontal compression; and (3) restraining bend with a sinistral movement of blocks. In particular, after an incipient fracturing stage, faults generated a pull-apart basin with terraced sidewall fault and graben subzones developed in the context of a dextral stepover during the lower part of late Miocene p.p. The occurrence of Triassic shales and evaporites played a fundamental role in the tectonic evolution of the study area. The salty material flowed along faults during this stage generating salt walls in root zones and salt push-up structures at the surface. During the purely compressive stage (middle part of late Miocene p.p.) the salt walls were squeezed to form extrusive mushroom-like structures. The large amount of clayish and salty material that surfaced was rapidly eroded and deposited into the basin, generating prograding fan clinoforms. The occurrence of shales and evaporites (both in the margins of the basin and in the proper infilling) favored folding of basin deposits, faulting, and the formation of rising blocks. Later, in the last stage (upper part of late Miocene p.p.), the area was affected by sinistral restraining conditions and faults must have bent to their current shape. The progressive folding of the basin and deformation of margins changed the supply points and finally caused the end of deposition and the beginning of the current erosive systems. On the basis of the interdisciplinary results, the Agost Basin can be considered a key case of the interference between salt tectonics and the evolution of strike-slip fault zones. The reconstructed model has been compared with several scaled sandbox analogical models and with some natural pull-apart basins.

  18. Distribution of crack density parameter in Central Betic Cordillera (Southern Spain)

    NASA Astrophysics Data System (ADS)

    Serrano, Inmaculada; Torcal, Federico; Morales, José

    2014-01-01

    In this study we have used high-resolution P- and S-wave velocity results to estimate crack density (ɛ, epsilon) and saturation ratio (ξ, xi) at a depth of 2 km in an intramountain basin and surrounding regions. Detailed observations of gravity, seismic profile and geological data reveal high ɛ consistent with large sedimentary thickness and minimum ɛ coinciding with elevations arising from the basement of the basin. From the distribution of seismic measurements of ξ it is possible to identify the presence of aquifers in detrital sediments, sandstone and dolostone. However, ξ does not show significant changes for the aquifers in geological formations made up also of schists and marbles. A low ξ anomaly in the western part could be associated with Triassic evaporite and clay rocks, and high values of ξ in the southwestern part near thermal springs may be imaging the intricate system of fractures which connect at depth with aquifer rocks.

  19. Late Jurassic plutonism in the southwest U.S. Cordillera

    USGS Publications Warehouse

    Barth, A.P.; Wooden, J.L.; Howard, K.A.; Richards, J.L.

    2008-01-01

    Although plate reconstructions suggest that subduction was an approximately steady-state process from the mid-Mesozoic through the early Tertiary, recent precise geochronologic studies suggest highly episodic emplacement of voluminous continental-margin batholiths in the U.S. Cordillera. In central and southern California and western Arizona, major episodes of batholithic magmatism are known to have occurred in Permian-Triassic, Middle Jurassic, and late Early to Late Cretaceous time. However, recent studies of forearc-basin and continental-interior sediments suggest that Late Jurassic time was probably also a period of significant magmatism, although few dated plutons of this age have been recognized. We describe a belt of Late Jurassic plutonic and hypabyssal rocks at least 200 km in length that extends from the northwestern Mojave Desert through the Transverse Ranges. The belt lies outboard of both the voluminous Middle Jurassic arc and the ca. 148 Ma Independence dike swarm at these latitudes. The plutons include two intrusive suites emplaced between 157 and 149 Ma: a calc-alkaline suite compositionally unlike Permian-Triassic and Middle Jurassic mon-zonitic suites but similar to Late Cretaceous arc plutons emplaced across this region, and a contemporaneous but not comagmatic alkaline suite. The Late Jurassic was thus a time of both tectonic and magmatic transitions in the southern Cordillera. ?? 2008 The Geological Society of America.

  20. Cenozoic migration of topography in the North American Cordillera

    NASA Astrophysics Data System (ADS)

    Mix, H. T.; Mulch, A.; Chamberlain, C. P.

    2010-12-01

    Continental topography is the result of complex interactions among mantle convection, continental dynamics, as well as climatic and erosional processes. Therefore, topographic evolution of mountain belts and continental interiors reflects directly upon the coupling between mantle and surface processes. It has recently been proposed that the modern topography of western North America is partly controlled by the removal of the subducting Farallon Plate and replacement of lithospheric mantle by hot asthenosphere, creating surface uplift of the Colorado Plateau, the southwestern United States and northern Mexico, while concomitant subsidence characterizes the central United States. How the topography of the Cenozoic North American Cordillera evolved in the past is largely unknown, yet currently debated tectonic models each have a predictable topographic response. We examined Cenozoic surface uplift patterns of western North America based on a record of ~3000 stable isotope proxy data. This data set is consistent with Eocene north to south surface uplift in the Cordillera, culminating in the assembly of an Eocene-Oligocene highland 3-4 km in elevation. The diachronous record of surface uplift and associated magmatism further supports tectonic models calling for the convective removal of mantle lithosphere or removal of the Farallon slab by buckling along an east-west axis. The Eocene-Oligocene development of similar-to-present day rainout patterns along the flanks of the Cordilleran orogen is therefore unlikely to be the result of late Mesozoic crustal thickening and associated development of an Andean-style Altiplano.

  1. Refining upon the climatic background of the Early Pleistocene hominid settlement in western Europe: Barranco León and Fuente Nueva-3 (Guadix-Baza Basin, SE Spain)

    NASA Astrophysics Data System (ADS)

    Blain, Hugues-Alexandre; Lozano-Fernández, Iván; Agustí, Jordi; Bailon, Salvador; Menéndez Granda, Leticia; Espígares Ortiz, Maria Patrocinio; Ros-Montoya, Sergios; Jiménez Arenas, Juan Manuel; Toro-Moyano, Isidro; Martínez-Navarro, Bienvenido; Sala, Robert

    2016-07-01

    The Early Pleistocene sites of Barranco León and Fuente Nueva-3 (Guadix-Baza Basin, SE Spain) have yielded thousands of Mode 1 or Oldowan lithic artifacts (both sites) and one tooth (in layer D, formerly 5 of Barranco León), today considered to be some of the earliest evidence of humans in western Europe at ca. 1.2-1.5 Ma. Previous quantitative paleoclimatic reconstructions based on herpetile assemblages indicated that, during the formation of these two sites, the mean annual temperature and mean annual precipitation were higher than they are now in the southeastern Iberian Peninsula, with lower continentality. Here, we propose new climatic reconstructions where the mean monthly temperature and precipitation and the difference between the four driest months and the four rainiest months are estimated. Climatograms are built in order to specify the distribution and variation of temperature and precipitation during the year, and the Aridity Indices of Gaussen, Lautensach-Mayer, Dantin-Revenga and De Martonne are used to characterize ombroclimatic differences. According to these new climatic parameters, rainfall distribution through the year shows considerably higher precipitation in every season except summer and early autumn, which remain drier and thus consistent with a Mediterranean climate pattern. No change is observed in the duration of the aridity period, which remains four months long. However, the value of the Aridity Index of De Martonne is higher than 20 (subhumid climate) in Barranco León and Fuente Nueva-3, whereas today it is lower than 20 (semi-arid climate), suggesting major changes in the ombroclimatic type. These results yield a more precise scenario for the paleoclimatic conditions that prevailed during the late Early Pleistocene in the Guadix-Baza Basin and permit us to contrast the ages obtained from numerical dating and biochronology. The very warm and humid climate reconstructed for both Barranco León and Fuente Nueva-3 suggests that, in

  2. Crustal structure beneath the Rif Cordillera, North Morocco, from active seismic profiling

    NASA Astrophysics Data System (ADS)

    Gallart, J.; Carbonell, R.; Diaz, J.; Gil, A.; Ruiz, M.; Harnafi, M.; Elmoudnib, L.; Elouai, D.; Levander, A.; Palomeras, I.; Cordoba, D.; Alonso-Chaves, F. J.

    2012-04-01

    The crustal structure along different domains of the Rif Cordillera is being investigated by active seismic methods (RIFSIS project). In a joint experiment between Spanish, Moroccan and American scientists, an 18 days-long operation was carried out in October 2011 involving about 50 participants in 25 field teams. Up to five shots of 1T each have been detonated at selected sites in North Morocco and recorded by about 900 Texans stations deployed along two profiles, in N-S and E-W directions respectively. Average station spacing was about 750 m along the 330 km-length profiles. The N-S line was extended northwards by a 70 km long segment in Spain, on the Betics. Southwards, this profile connects with the one recorded in 2010 across the Atlas Mountains (SIMA experiment), hence delineating a 700 km-long wide-angle seismic transect across the Betics-Rif-Atlas systems. A complementary operation involving onshore-offshore recordings in Spanish and Moroccan sides of the Westen Alboran Basin could be performed in parallel, taking advantage of a marine multichannel seismic experiment ongoing in the Alboran Sea during the same period, using the facilities of the Spanish 'Sarmiento de Gamboa' vessel. Preliminary analysis of processed datasets already reveals the existence of major variations in crustal thicknesses, especially along the E-W profile that documents differences of more than 10 km in Moho depths. The thickest crust is found beneath the external Rif domain, with a rapid thinning eastwards, in the foreland and Atlasic terranes up to the Algerian border.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  4. Time and mode of exhumation of the Cordillera Blanca batholith (Peruvian Andes)

    NASA Astrophysics Data System (ADS)

    Margirier, Audrey; Audin, Laurence; Robert, Xavier; Herman, Frédéric; Ganne, Jérôme; Schwartz, Stéphane

    2016-08-01

    The Cordillera Blanca batholith (12-5 Myr) forms the highest Peruvian summits and builds the footwall of the Cordillera Blanca normal fault (CBNF). Even if several models have been proposed, the processes driving both the exhumation of the Cordillera Blanca and extensional deformation along the CBNF are still debated. Here we quantify the emplacement depth and exhumation of the batholith of the northern Peru arc from the late Miocene to present. Based on a compilation of crystallization ages and new thermobarometry data in the Cordillera Blanca batholith, we propose that the batholith was emplaced at a depth of ~3 km in successive sills from 14 to 5 Ma. By contrast, the younger rocks exposed at the surface were emplaced the deepest (i.e., ~6 km) and are located close to the CBNF, suggesting post 5 Ma tilting. Furthermore, a formal inversion of the thermochronologic data indicates an increase of the exhumation rates in the Cordillera Blanca during the Quaternary. The higher predicted exhumation rates correlate with areas of high relief, both in the northern and central part of the Cordillera Blanca, suggesting that Quaternary valley carving by glaciations have a significant impact on the latest stage of the Cordillera Blanca exhumation (2-0 Ma).

  5. Geology of the El Recodo Cu-Mo prospect, SE. Cordille-ra central, Dominican Republic

    SciTech Connect

    Dominguez, H.S.; Lewis, J.F.

    1985-01-01

    The main intrusive phase in the El Recodo area is a small stock of leucocractic quartz diorite which intrudes an unmetamorphosed Upper Cretaceous sequence of andesites, tuffs, agglomerates, breccias and minor interbedded limestones. At least three other intrusive phases might be related to the emplacement of the main quartz diorite stock: 1) porphyritic andesites, 2) a series of gabbros and hornblende gabbros and 3) late stage aplite, porphyritic dacite and mineralized quartz-epidote veins. Emplacement of this last phase was accompanied by extensive brecciation and hydrothermal alteration.Three distinct stages of hydrothermal alteration are recognized in the andesites an associated basic to intermediate intrusives: 1) pyroxene-hornblende alteration to chlorite +/- epidote-magnetite, 2) incipient plagioclase alteration to kaolinite-quartz and 3) advanced plagioclase alteration to sericite-quartz +/- chamosite. In altered quartz diorite and dacite porphyries the association K-feldspar-biotite indicates the highest grade of hydrothermal alteration. Mineralization is ubiquitous. Pyrite, chalcopyrite and bornite occur as thin stringers, disseminations and replacements of original mafic minerals. Throughout the area mineralized outcrops are thoroughly stained with a mixture of secondary limonite-hematite and minor chalcocite-malachite. The strongest mineralized areas correspond with significant soil, rock and stream sediment Cu and Mo Anomalies.

  6. A new climate and glacier baseline for the Cordillera Vilcanota, Peru, reduces critical information gaps

    NASA Astrophysics Data System (ADS)

    Salzmann, Nadine; Huggel, Christian; Rohrer, Mario; Silverio, Walter; Mark, Bryan G.; Cochachin, Alejo; Suarez, Wilson; Giráldez, Claudia

    2013-04-01

    The Cordillera Vilcanota in the Southern Peruvian Andes is the second largest ice-covered Cordillera in Peru (after the Cordillera Blanca) and serves for the Cusco Region as a temporary water storage for fresh-water and hydropower generation and irrigation. Despite the Cordillera Vilcanota's size and socio-economic relevance, there has so far no comprehensive baseline data been available for climate and glacier evolution. In the framework of two jointly launched -Peruvian-Swiss climate change impact and adaptation programs (Climate Change Adaptation Programm - PACC; Glacier Change Adaptation and Desaster Risk Reduction Programm - Glacier 513) significant efforts have been undertaken and are on the way to create a climate, glacier and hazard baseline for the Cordillera Vilcanota. Because of the remoteness of the area and the scarcity of available data, multiple sources such as climate stations, climate reanalysis and satellite data have been collected, processed and analyzed. Based on our data, we found only marginal glacier changes between 1962 and 1985, but a massive ice loss since 1985 (about 30% of area and about 45% of volume). These high numbers corroborate studies from other glacierized cordilleras in Peru. The climate data show overall a moderate increase in air temperature, and mostly weak and not significant trends for precipitation sums, which probably cannot fully explain the observed substantial ice loss. The likely increase of specific humidity in the upper troposphere, where the glaciers are located, probably played a major role in the observed massive of the Cordillera Vilcanota over the past decades. The mass balance measurements initiated in 2010 on two glaciers of the Cordillera Vilcanota, and the climate station installed in 2011 on one of the glaciers, preliminarily indicate that ice loss (in water equivalent) is clearly lower that in the Cordillera Blanca. In the near future the data will provide new and important insights on climate and

  7. Tectonics of the North American Cordillera near the Fortieth Parallel

    USGS Publications Warehouse

    King, P.B.

    1978-01-01

    The North American Cordillera near the Fortieth Parallel consists of the following tectonic units: 1. (A) To the east is a reactivated cratonic area, in the Southern Rocky Mountains and Colorado Plateau, in which the supracrustal rocks (Cambrian to Cretaceous) were broadly deformed during the late Cretaceous-Paleocene Laramide orogeny, and the Precambrian basement was raised in folds of wide amplitude. 2. (B) West of it is a miogeosynclinal belt, in the eastern Great Basin, in which a thick sequence of Paleozoic carbonates and related deposits was thrust eastward along low-angle faults during the middle to late Cretaceous Sevier orogeny. The miogeosyncline is the downwarped western margin of the original North American continent, and its rocks accumulated on Precambrian basement. 3. (C) Beyond is a eugeosynclinal belt, in the western Great Basin, in which Paleozoic graywackes, cherts, and volcanics were thrust easteastward along low-angle faults during several Paleozoic orogenies - the mid-Paleozoic Antler orogeny which produced the Roberts thrust on the east, and the end-Paleozoic Sonoma orogeny which produced the Golconda thrust farther west. The Paleozoic eugeosynclinal rocks accumulated on oceanic basement. They are overlapped from the west by Triassic and Jurassic shelf deposits, which pass westward into eugeosynclinal deposits. 4. (D) A volcanic island-arc belt existed on the sites of the Sierra Nevada in Paleozoic and early Mesozoic time, which produced thick bodies of sediments and volcanics. During the mid-Mesozoic Nevadan orogeny these were steeply deformed and thrust westward over subduction zones, and were intruded by granitic rocks that rose from the upper mantle to form great batholiths. 5. (E) West of the Sierra Nevada, in the Great Valley, is a great sedimentary embankment of later Mesozoic flysch or turbidite, largely younger than the supracrustal rocks of the Sierra Nevada and the Nevadan orogeny. It was formed of the erosional products of the

  8. Proglacial Groundwater Flux and Storage in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    As tropical glaciers continue to rapidly retreat in the Cordillera Blanca, Peru, dry-season water resources are becoming more dependent on groundwater baseflow. Therefore, understanding the flux and storage of proglacial groundwater is necessary to forecast how groundwater storage can offset decreasing water resources. Recent studies of the Rio Santa Watershed, which drains the western slopes of the Cordillera Blanca, have identified that groundwater is the largest contributor to outflow from many watersheds during the dry season and that the flux of groundwater is temporarily available (< 4years). These groundwater estimates are based on chemical mass balance models that use hydrochemical and isotopic results primarily from surface water samples and stream discharge measurements. Although effective, this approach is limited by the absence of data from proglacial aquifers. In July, 2012, we installed six groundwater monitoring wells to a maximum depth of 6 m in two proglacial valleys in the Cordillera Blanca. For each well, water samples were collected for hydrochemical and isotopic analysis, slug-tests were conducted to measure hydraulic conductivity, and water levels were continuously monitored using pressure transducers. In both valleys we observed an upper layer of clay to silt sized glaciolacustrine material at each drill site. This layer was typically less than 5 m in thickness and had a low hydraulic conductivity (< 10-7 m/s). Underlying the clay layer were water bearing units of course material (either well-sorted sand/gravel or talus deposits) with an average hydraulic conductivity of 10-5 m/s. Additionally numerous discontinuous sand lenses and localized glaciofluvial gravel deposits were observed within the clay layer. The glaciolacustrine deposits behave as confining units that were capable of generating localized artesian conditions in the coarse grain units. The occurrence of the clay units adjacent to the main stream channels suggests that the

  9. Crustal structures from MT soundings in the Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Majorowicz, J. A.; Gough, D. Ian

    1991-03-01

    Magnetotelluric soundings have been made across the Intermontane and Omineca tectonic belts of the Canadian Cordillera between latitudes 51.5 and 53.5°N. The frequency range, 0.016 to 130 Hz, gives penetration into the middle crust. In this part of the Cordillera the upper crust has very low resistivities, ranging from 3 to 300 ohm m, compared with continental shields and stable platforms. The most resistive rocks (100-300 ohm m) rise to the surface as the Coast Plutonic Complex is approached, and we identify them with confidence as granodiorites and similar plutonic rocks (hereafter "plutonics"). Phase pseudosections and resistivity-depth sections are used to infer that these plutonics continue northeastward from the Coast Plutonic Complex, across more than half of the width of the Intermontane Belt, with a sharp edge well located in the phase pseudosections. The Miocene basalts have extremely low resistivities (3-30 ohm m) and form a sheet 0-2 km thick covering the plutonics. The very low resistivities in all rocks are probably caused by saline hot water in connected spaces, with low fracture density giving relatively high resistivities in the plutonic rocks, and much greater fracture densities giving extremely low resistivities in the volcanics. This is consistent with the lower mechanical strength of basalt as against granodiorite; the volcanics may have accommodated most of the post-Miocene extension of the upper crust. Off the edge of the plutonic rocks beneath the basalts, very low resistivities extend at least into the middle crust; this deep extension of the highly conductive rock may mark the feeder channel of the Miocene basalt to the surface. Three resistivity-depth sections show a fall of resistivity with depth, to values of 10 ohm m or even less, at a depth of only 8 km. Heat flow is high in the region, and the temperature at 8 km may be as high as 350°C. The increase in conductivity may be due in part to the temperature effect on NaCl solutions

  10. Geochronology of Tropical Alpine Glaciations From the Cordillera Huayhuash, Peru

    NASA Astrophysics Data System (ADS)

    Hall, S. R.; Farber, D. L.; Rodbell, D. T.; Finkel, R. C.; Ramage, J. M.; Smith, J. A.; Mark, B. G.; Seltzer, G. O.

    2004-12-01

    The Cordillera Huayhuash of the Central Peruvian Andes (10.3° S, 76.9° W) is an ideal range to study regional climate signals and variations in paleo-ice volumes. Located between the Cordillera Blanca to the north and the Junin region to the south, the range trends nearly north-south with modern glaciers confined to the high peaks (>4800 m). Cross-cutting relationships, geomorphology, and correlation with surface exposure dated moraines in the nearby Cordillera Blanca suggest the region preserves a rich record of tropical glaciation. In order to determine the glacial chronology we mapped and dated glacial features of the Jahuacocha valley (which drains the western side of the range) and two eastern drainages, the Mitococha valley, and the Carhuacocha valley. At each locality we used ASTER data, aerial photographs, and GPS to map glacial features both within main valleys and tributaries. We sampled quartz-bearing erratics on moraine crests as well as ice-polished bedrock surfaces for exposure age dating using in situ produced cosmogenic 10Be and 26Al. In the Jahuacocha valley, the greatest ice extent reached an elevation of ˜4090m and moraine crest boulders yield and age of ˜11.2 ±0.6 ka suggesting a significant late Glacial ice advance or stillstand. A younger cluster of moraines exists ˜1 km up-valley at an elevation of ˜4100m. These moraines, dated at ˜8.0 ±1.0 ka, suggest an early Holocene advance. In the Mitococha valley, a young moraine and polished bedrock dated at ˜0.2 ka and ˜11.4 ±0.4 ka respectively span the late Glacial through recent. The late Glacial features of this eastern drainage occur at an elevation of ˜4100m while the recent events occur at an elevation of ˜4380m. Our preliminary results suggest that all three valleys experienced a very similar glacial history with minor differences likely due to the variations in valley morphology. Comparing the chronology of glaciation in the Cordillaera Huayhuash with that in regions to the

  11. Emeralds in the Eastern Cordillera of Colombia: Two tectonic settings for one mineralization

    NASA Astrophysics Data System (ADS)

    Branquet, Yannick; Laumonier, Bernard; Cheilletz, Alain; Giuliani, Gaston

    1999-07-01

    Colombian emeralds are formed through a hydrothermal-sedimentary process. On the western side of the Eastern Cordillera, the deposits are linked by tear faults and associated thrusts developed during a compressive tectonic phase that occurred at the time of the Eocene-Oligocene boundary, prior to the major uplift of the Cordillera during the Andean phase (middle Miocene). On the eastern side of the Cordillera, emerald mineralization occurred earlier, at the time of the Cretaceous-Tertiary boundary, during a thin-skinned extensional tectonic event linked to evaporite dissolution. This event predates the Andean phase, during which this part of the chain was folded and thrust over the Llanos foreland.

  12. Large Scale Deformation of the Western US Cordillera

    NASA Technical Reports Server (NTRS)

    Bennett, Richard A.

    2001-01-01

    Destructive earthquakes occur throughout the western US Cordillera (WUSC), not just within the San Andreas fault zone. But because we do not understand the present-day large-scale deformations of the crust throughout the WUSC, our ability to assess the potential for seismic hazards in this region remains severely limited. To address this problem, we are using a large collection of Global Positioning System (GPS) networks which spans the WUSC to precisely quantify present-day large-scale crustal deformations in a single uniform reference frame. Our work can roughly be divided into an analysis of the GPS observations to infer the deformation field across and within the entire plate boundary zone and an investigation of the implications of this deformation field regarding plate boundary dynamics.

  13. Large Scale Deformation of the Western U.S. Cordillera

    NASA Technical Reports Server (NTRS)

    Bennett, Richard A.

    2002-01-01

    Over the past couple of years, with support from NASA, we used a large collection of data from GPS, VLBI, SLR, and DORIS networks which span the Western U.S. Cordillera (WUSC) to precisely quantify present-day large-scale crustal deformations in a single uniform reference frame. Our work was roughly divided into an analysis of these space geodetic observations to infer the deformation field across and within the entire plate boundary zone, and an investigation of the implications of this deformation field regarding plate boundary dynamics. Following the determination of the first generation WUSC velocity solution, we placed high priority on the dissemination of the velocity estimates. With in-kind support from the Smithsonian Astrophysical Observatory, we constructed a web-site which allows anyone to access the data, and to determine their own velocity reference frame.

  14. Large Scale Deformation of the Western U.S. Cordillera

    NASA Technical Reports Server (NTRS)

    Bennett, Richard A.

    2002-01-01

    Over the past couple of years, with support from NASA, we used a large collection of data from GPS, VLBI, SLR, and DORIS networks which span the Westem U.S. Cordillera (WUSC) to precisely quantify present-day large-scale crustal deformations in a single uniform reference frame. Our work was roughly divided into an analysis of these space geodetic observations to infer the deformation field across and within the entire plate boundary zone, and an investigation of the implications of this deformation field regarding plate boundary dynamics. Following the determination of the first generation WUSC velocity solution, we placed high priority on the dissemination of the velocity estimates. With in-kind support from the Smithsonian Astrophysical Observatory, we constructed a web-site which allows anyone to access the data, and to determine their own velocity reference frame.

  15. Ambient noise tomography across the southern Alaskan Cordillera

    NASA Astrophysics Data System (ADS)

    Ward, Kevin M.

    2015-05-01

    I present the results of an extensive data mining effort integrating 197 permanent and temporary seismic stations into a Rayleigh wave ambient noise study across southern Alaska and westernmost Canada. Principal observations of my tomography model are largely consistent with mapped geology features and previous geophysical studies while providing previously unavailable, laterally continuous details of the southern Alaskan Cordillera lithosphere. At intermediate periods, a geophysically uniform crust is observed north of the Denali Fault and is consistent with a sharp transition in crustal thickness. Under the Wrangell volcanic belt, a prominent low-phase-velocity anomaly correlates well with the lateral extent of a relative low-gravity anomaly and Neogene surface volcanics. At longer periods, a low-phase-velocity anomaly bounds the inferred eastern extent of the subducted Yakutat microplate beneath the Wrangell volcanic belt.

  16. The Servita Fault, Colombian Eastern Cordillera: Origin, Geotectonics, and Seismicity

    NASA Astrophysics Data System (ADS)

    Chicangana, G.; Kammer, A.; Vargas Jiménez, C. A.; Caneva, A.; Pedraza, P.; Salcedo, E.; Gomez, A.; Muñoz, F.

    2014-12-01

    The Servita fault is a thrust located in the center of Colombia and whose main scarp is at 5 km west of Villavicencio (500.000 inhabitants). According to geophysics data as gravity, magnetic, and seismic, this fault was confirmed how a large cortical structure in the Colombian Eastern Cordillera. The Servita fault possibly was originated like a suture that derived of a continental collision in Late Mesoproterozoic times when Rodinia was conform totally. The Servita Fault as normal fault in Mesozoic times contributed to the Colombian Cretaceous basin development. In Late Cretaceous because to collision of the Caribbean plate with the northwestern corner of South America a strong compressive stress was occur and kinematics changes were presented in the normal faults restrained to the basin like among others the Servita Fault, where these were converted in inverse faults. From early Pliocene until Present times the Servita Fault controlled the growth of the Cordillera and the Llanos foothills in this sector of Central Colombia. Result of this is the seismicity activity registered for this region from historical times (less of 500 years for Colombian case). Two earthquakes have transcended in this region in last three centuries: the first one occurred on October 18th, 1743 with a current probabilistic magnitude greater than 6.5 and the second one struck on May 24th, 2008 with a M = 5.9. In this work we show how this fault has develop from its origin, and how this can would produce a M > 6.5 earthquake very close to metropolitan area of Bogota D.C., and Villavicencio. This earthquake would destroy both urban areas resulting in high losses in lives and economic terms. The seismicity activity of the Servita Fault and its associated structures is registered by the National Seismological Network of Colombia and the Sabana de Bogotá Seismological Network.

  17. The Cretaceous stratigraphy of the Western Cordillera Oriental, Columbia

    SciTech Connect

    Allen, R.B.; Alfonso, C.A.; Ressetar, R.; Salazar, A. ); Ballesteros, I.; Cardozo, E.; Laverde, F.; Ramirez, C. ); Moreno, J.M. ); Rubiano, J.; Sarmiento, L. )

    1993-02-01

    During 1987 and 1988, a major field project sponsored by Tenneco was undertaken along the west flank of the Cordillera Oriental of Colombia between Alpujarra (between the Neiva and Girardot Sub-Basins) and the Middle Magdalena Basin (Cimitarra area). An important result of this study was the documentation of pronounced regional variation in the age, thickness, and facies of the Cretaceous section. The maximum thickness estimated was 7 km for the Bogota-Villeta section, with ages as old as Berriasian. This section can be divided into 4 or 5 depositional sequences. A clastic source to the west or southwest is indicated for the lower sequence 1 (and 2 ), an eastern source dominated sequences 3 and 4, and eastern and western sources supplied the upper sequence. Toward the north the section thins to an estimated 3-5 km but still ranges in age throughout the Cretaceous. Southward, on the other hand, the Cretaceous thins to about 2 km and is restricted to Aptian-Albian and younger ages. The variations in ages, facies, and thickness are consistent with recent models of the evolution of the Cretaceous basin. During the Neocomian, the Bogata area formed the main depocenter of the basin and was characterized by restricted facies and turbidites, suggesting steep, possibly faulted basin margins. Facies to the north, near the Middle Magdalena Basin, indicate shallower water, possibly a platform. By the end of the Early Cretaceous, expansion of the marine basin out of the central Cordillera Oriental and regionally more constant facies indicate the onset of dominantly thermal subsidence. The end of the Cretaceous was marked by regression and asymmetric clastic input from east and west of the basin.

  18. Recent glacier retreat and climate trends in Cordillera Huaytapallana, Peru

    NASA Astrophysics Data System (ADS)

    López-Moreno, J. I.; Fontaneda, S.; Bazo, J.; Revuelto, J.; Azorin-Molina, C.; Valero-Garcés, B.; Morán-Tejeda, E.; Vicente-Serrano, S. M.; Zubieta, R.; Alejo-Cochachín, J.

    2014-01-01

    We analyzed 19 annual Landsat Thematic Mapper images from 1984 to 2011 to determine changes of the glaciated surface and snow line elevation in six mountain areas of the Cordillera Huaytapallana range in Peru. In contrast to other Peruvian mountains, glacier retreat in these mountains has been poorly documented, even though this is a heavily glaciated area. These glaciers are the main source of water for the surrounding lowlands, and melting of these glaciers has triggered several outburst floods. During the 28-year study period, there was a 55% decrease in the surface covered by glaciers and the snowline moved upward in different regions by 93 to 157 m. Moreover, several new lakes formed in the recently deglaciated areas. There was an increase in precipitation during the wet season (October-April) over the 28-year study period. The significant increase in maximum temperatures may be related to the significant glacier retreat in the study area. There were significant differences in the wet season temperatures during El Niño (warmer) and La Niña (colder) years. Although La Niña years were generally more humid than El Niño years, these differences were not statistically significant. Thus, glaciers tended to retreat at a high rate during El Niño years, but tended to be stable or increase during La Niña years, although there were some notable deviations from this general pattern. Climate simulations for 2021 to 2050, based on the most optimistic assumptions of greenhouse gas concentrations, forecast a continuation of climate warming at the same rate as documented here. Such changes in temperature might lead to a critical situation for the glaciers of the Cordillera Huaytapallana, and may significantly impact the water resources, ecology, and natural hazards of the surrounding areas.

  19. Estimation of slip rates and seismic hazard parameters using conventional techniques of structural geology in a slow-moving fault: Alhama de Murcia - Alcantarilla segment of the Alhama de Murcia Fault (Murcia, SE Spain)

    NASA Astrophysics Data System (ADS)

    Herrero-Barbero, Paula; Álvarez-Gómez, José Antonio; Jesús Martínez-Díaz, Jose

    2017-04-01

    Alhama de Murcia - Alcantarilla segment, seems to absorb part of the regional tectonic shortening. That is why the relief uplifted by the Alhama de Murcia - Alcantarilla segment during the Quaternary is significantly less prominent than the mountains fronts generated by the Carrascoy Fault. Even so, Alhama de Murcia - Alcantarilla segment should be considered as an active structure with implications for seismic hazard. The maximum size of earthquake is calculated to be Mw 6.3 - 6.6 according to magnitude-area and magnitude-length scaling relationships, with a mean recurrence interval lower than 10.000 years for the slip rate obtained. In the same way, Mw 5.0 earthquakes, such as those recorded in the historical seismic catalog, are estimated to have a recurrence interval lower than 50 years. These earthquakes could be very destructive in densely populated areas, as is the case of SE Spain, so they should be considered in seismic-hazard analysis.

  20. At the craton edge: Geodynamic evolution of the southern Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    DiCaprio, L.; Eaton, D. W. S.

    2016-12-01

    In the southern Canadian Cordillera, the thermal and mechanical interface with the craton may influence the geodynamic evolution of the lithosphere-asthenosphere system. Evidence including recent Rayleigh-wave tomography studies suggest that, beneath the southern Canadian Cordillera, the mantle lithosphere is virtually absent. Here, the boundary between craton and Cordillera also marks a step change in measured surface heat flux and a westward termination of magnetic anomalies. This study provides a numerical simulation of lithospheric-mantle removal by geodynamic processes that include delamination, viscous erosion, and mantle dripping. An additional constraint to the geodynamic model comes from thermochronologic data demonstrating long wavelength uplift of the cordilleran plateau in the Eocene. We have developed a suite of 2D visco-plastic models of a transect through the southern Canadian Cordillera and North American Craton. Sensitivity tests elucidate a range of geodynamic models that are consistent with tomographic results and the observed uplift history.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  2. The Padul normal fault activity constrained by GPS data: Brittle extension orthogonal to folding in the central Betic Cordillera

    NASA Astrophysics Data System (ADS)

    Gil, Antonio J.; Galindo-Zaldívar, Jesús; Sanz de Galdeano, Carlos; Borque, Maria Jesús; Sánchez-Alzola, Alberto; Martinez-Martos, Manuel; Alfaro, Pedro

    2017-08-01

    The Padul Fault is located in the Central Betic Cordillera, formed in the framework of the NW-SE Eurasian-African plate convergence. In the Internal Zone, large E-W to NE-SW folds of western Sierra Nevada accommodated the greatest NW-SE shortening and uplift of the cordillera. However, GPS networks reveal a present-day dominant E-W to NE-SW extensional setting at surface. The Padul Fault is the most relevant and best exposed active normal fault that accommodates most of the NE-SW extension of the Central Betics. This WSW-wards dipping fault, formed by several segments of up to 7 km maximum length, favored the uplift of the Sierra Nevada footwall away from the Padul graben hanging wall. A non-permanent GPS network installed in 1999 constrains an average horizontal extensional rate of 0.5 mm/yr in N66°E direction. The fault length suggests that a (maximum) 6 magnitude earthquake may be expected, but the absence of instrumental or historical seismic events would indicate that fault activity occurs at least partially by creep. Striae on fault surfaces evidence normal-sinistral kinematics, suggesting that the Padul Fault may have been a main transfer fault of the westernmost end of the Sierra Nevada antiform. Nevertheless, GPS results evidence: (1) shortening in the Sierra Nevada antiform is in its latest stages, and (2) the present-day fault shows normal with minor oblique dextral displacements. The recent change in Padul fault kinematics will be related to the present-day dominance of the ENE-WSW regional extension versus NNW-SSE shortening that produced the uplift and northwestwards displacement of Sierra Nevada antiform. This region illustrates the importance of heterogeneous brittle extensional tectonics in the latest uplift stages of compressional orogens, as well as the interaction of folding during the development of faults at shallow crustal levels.

  3. Crust structure across the Rif Cordillera from 'RIFSIS' seismic refraction and wide-angle reflection experiment

    NASA Astrophysics Data System (ADS)

    Gil, Alba; Gallart, Josep; Díaz, Jordi; Carbonell, Ramon; Harnafi, Mimoun; Levander, Alan

    2013-04-01

    The Rif Cordillera, located in North Morocco forms, together with the Betic Range, the Gibraltar Arc around the Alboran Sea. This asymmetric curved mountain belt originated during a Miocene continent-continent collision as a result of the westward motion of the Alboran domain between northwest Africa and Iberia. The complexity of the area favored the proposition of diverse tectonic models, such as roll-back, accompanied and followed by lithospheric convective down-welling, and delamination. In this study, we present models of crustal structure derived from a seismic refraction and wide-angle reflection experiment which took place in October 2011 within the Spanish project RIFSIS complemented by the US-PICASSO one. Two profiles oriented N-S and E-W respectively were carried out across the Rif domains. Five shots of 1 Tn each were detonated along the lines and at the crossing point, recorded by about 900 stations from US-Iris pool deployed at an average spacing of 750 m. The N-S line was extended northwards by a 70 km long segment in Spain, in the Betic Range. Southwards, this profile connects with the one recorded in 2010 across the Atlas Mountains, within the SIMA project. The interpreted crustal structure differentiates two sedimentary layers on top of the basement, inferred from the observed first arrivals at short offsets, followed by upper, mid and lower crustal levels constrained by reflected phases visible in the record sections. The bottom of the crust is well defined from PmP phases, although the absence of Pn arrivals prevents to constrain upper mantle velocities. Average velocity values for the different layers in the models are respectively: 3.5 and 4.2 km/s for the sediments, 5.9, 6.3 and 6.6 km/s within the crust, and 8 km/s below Moho. These velocity depth models obtained at the Rif Cordillera hold major variations in crustal thickness, especially along the E-W profile, that shows a rapid change of 15-20 km in Moho depths within 30 km horizontal

  4. Zircon U-Pb geochronology and heavy mineral composition of the Camaná Formation, southern Peru: Constraints on sediment provenance and uplift of the Coastal and Western Cordilleras

    NASA Astrophysics Data System (ADS)

    Alván, Aldo; von Eynatten, Hilmar; Dunkl, István; Gerdes, Axel

    2015-08-01

    In the forearc of the Central Andes of southern Peru, the Cenozoic Camaná Basin (16°25‧S to 17°15‧S) forms a ∼NW-SE elongated depression filled with coarse-grained deltaic and fluvial deposits. These deposits are termed Camaná Formation. We have applied for the first time, advanced multi-method analytical techniques to sediments of the Camaná Formation in order to define precise sedimentation ages, unravel sediment provenance, and to explain its tectono-sedimentary evolution. Zircon U-Pb geochronology and multiple geological evidences suggest that the Camaná Formation ranges in age from Late Oligocene to Late Miocene, and may even extend into the Pliocene. We propose a provenance model for the Camaná Formation based on U-Pb geochronology, heavy mineral analysis, and single-grain mineral chemistry by LA-ICP-MS. This model suggests that sediments of the lower part of the Camaná Formation derive from rocks forming the Coastal Cordillera (i.e. the Arequipa Massif and the San Nicolas Batholith) and the widespread ignimbrites of the ∼24-10 Ma Huaylillas volcanic arc. In contrast, sediments of the upper part of the Camaná Formation derive predominantly from rocks forming the Western Cordillera (i.e. the Arequipa Massif, the Tacaza Group, and the Coastal Batholith) and products of the ∼10-3 Ma Lower Barroso volcanic arc). Accordingly, we infer that uplift of the Coastal Cordillera has strongly influenced deposition of the Camaná Formation since Late Oligocene. A marked shift in provenance within the Camaná Formation at around Middle to Late Miocene time (14-12 Ma) suggests drastic uplift of the Western Cordillera at that time. This uplift has triggered increased relief and erosion in the Western Cordillera, and subsequent deposition of fluvial conglomerates in the Camaná Basin.

  5. New glaciological research projects in the Cordillera Vilcanota - Cusco - Peru

    NASA Astrophysics Data System (ADS)

    Montoya, Nilton; Molina, Edwin; Schauwecker, Simone; Haeberli, Wilfried; Giraldez, Claudia; Drenkhan, Fabian; Huggel, Christian

    2015-04-01

    Tropical glaciers are highly sensitive to alterations in climate and therefore good indicators for global climate change. Glaciers located in Peru represent 71% of all tropical glaciers in the world, and have shown a significant area reduction of about 43% within the last 40 years mainly due to the increase in surface temperature. Tropical glaciers play a particular role as freshwater reservoirs and buffers to river discharge variability and water scarcity within a pronounced wet and dry season. Their monitoring is extraordinarily important but few studies exist on mass balance. The Cordillera Vilcanota, at the origin of the Rio Vilcanota-Urubamba, contains about 25% of all glaciers in Peru. In recent decades, glacier shrinkage has accelerated in this mountain range. Between 1988 and 2010, glacier area was reduced at an annual rate of about 4 km2 (1.1 %) from some 360 km2 to about 270 km2 (25%). A total volume loss of 40-45% (from 17-20 km3 to 9.2-12.4 km3) can be estimated for the period 1962-2006, with an accelerated rate since the 1980s. In 2010/11, first point net mass balance measurements were carried out on Suyuparina glacier and the adjacent Quisoquipina glacier. In 2013, mass balance measurements were reinitiated in the frame of a long-term monitoring campaign. The first year of direct mass balance measurements (stakes and pits) show that ablation is highly influenced by the complex microtopography of the glacier, mainly characterized by the existence of ice cliffs, causing a spatially heterogeneous ablation pattern. There is a large scatter in point mass balance in function of elevation, which makes it difficult to estimate accurately the equilibrium line altitude (ELA) and the annual total glacier mass balance from these point measurements. For the hydrological year 2013/14, stake measurements for sites on the lower part of the glacier varied between +0.2 and -4 m w.e. (water equivalent), while accumulation in the uppermost part of the glacier showed

  6. Relative Quantification of Costal Cordillera (Ecuador) Uplift : Preliminary Results from Quantitative Geomorphology

    NASA Astrophysics Data System (ADS)

    Reyes, Pedro; Dauteuil, Olivier; Michaud, François

    2010-05-01

    The coastal cordillera of Ecuador (culminating point around 800 m) includes on its littoral margins uplifted marine terraces (maximum known 360 m). The coastal cordillera constitutes an important barrier of drainage and on nearly 600 km the drainage resulting from the Andes is diverted towards Río Guayas in the South and Río Esmeraldas in North. What is the uplifting mode of the coastal cordillera? For how long it has constituted a barrier of drainage? Does the coastal cordillera rising be linked with the littoral margin rising? Does the cordillera have raised in a homogeneous or segmented way? What is the geodynamic process of the uplift of the cordillera? Can this uplift be related with the subduction of the Carnegie ridge? The first objective of this work is to analyze the morphology of the coastal cordillera with helps of quantitative geomorphology using digital techniques such as DEM (realized with a resolution of 30 m by Marc Souris, IRD), to specify the evolution of the coastal cordillera uplift. This study was carried out starting combining analysis of morphology, maps derived from the slopes and anomalies of the drainage of the hydrographic network. In the second time, three methods were applied to DEM data using the ArcGIS software: 1) the digitalization and the interpolation of basal surface of the last marine formation of regional distribution (the Borbón formation on the geological map of Ecuador) to determine paleo-horizontal and to see its deformation; 2) the extraction of 109 profiles of rivers which allow us to calculate for each river the vertical, horizontal, and total deviation compared to the theoretical profile of the river and the associated SL index; 3) the measurement of the relief incision (depth + half width of the valley, on the whole 7500 measurements) according to the method of Bonnet et al. (1998). We adapted this method to be able to represent the state of incision in any point, correcting from the influence of the lithology and

  7. Metallogeny of epithermal gold deposits in the western US Cordillera

    SciTech Connect

    Duke, N.A.

    1985-01-01

    The mid-Tertiary sediment-, volcanic-, and detachment fault-hosted epithermal gold deposits (EGDs) of the western US Cordillera favor the outboard side of the tectonically thickened miogeoanticlines. Post Mesozoic accretion, this cratonic shelf-oceanic basin transition zone underwent a period of extensional uplift that thinned the brittle upper crust through listric-normal and detachment faulting, and the decoupled metamorphic infrastructure by ductile necking. The EDGs formed in the upper crust peripheral to tectonically exposed metamorphic core complexes synchronously with active extension. They demonstrate close space/time relationships to the centers of ash flow tuff eruptions that characterized this period. In general the metal concentrated in EDGs had a common source and transport mechanism. The fact that major EGDs occur along obducted oceanic thrust plates indicates that the gold was originally scavaged from oceanic successions during dewatering along the thrust structures. The metal was again mobilized in meteoric dominated hot spring systems operating within volcani-tectonic sinks occurring at ignimbrite eruptive centers. As a result, the siting of both sediment- and volcanic-hosted EGDs is controlled largely by proximity to the mid-Tertiary paleosurface. Specific controls for the precipitation of gold varies with deposit type but critical behavior of the ore-bearing fluid and/or redox reactions between migrating fluids and reduced lithology crosscut by permeable structures are primary.

  8. Comparison of terrane accretion in modern Southeast Asia and the Mesozoic North American Cordillera

    NASA Astrophysics Data System (ADS)

    Silver, Eli A.; Smith, Randall B.

    1983-04-01

    The western part of the North American Cordillera has been divided into numerous suspect terranes. Some of these terranes have traveled hundreds to thousands of kilometres between the time of their formation and their final incorporation into the accretionary belt of the Cordillera. Most of the terranes appear to be relics of island arcs, oceanic plateaus and islands, continental margin fragments, and complex accretionary terranes, the latter including melange belts, ophiolite fragments, and thrust-faulted forearc provinces. Because the terranes have complex histories and diverse stratigraphies, it has been difficult to envisage an actualistic setting for the Mesozoic Cordillera. Here we propose an analogy with the tectonic setting of the Indo-Pacific region, from the Tonga trench on the east to eastern Indonesia on the west. This region comprises several distinct island arcs, several large oceanic plateaus, numerous accretionary terranes, melange zones, ophiolite fragments, and a variety of continental fragments, all moving toward the central collision zone. Like the Cordillera, this part of the Indo-Pacific region is undergoing oblique convergence, driven by relatively high rates of movement between the oceanic plates and the collision zone. Also analogous to the Cordillera is the formation of a foreland fold and thrust belt, developing between the collision zone and the Australian continent, and a zone of basement-rooted foreland folds, suggestive of an early Laramide style of deformation. *Present address: Sohio Petroleum Company, Denver, Colorado 80202

  9. Dynamics of metal tolerant plant communities' development in mine tailings from the Cartagena-La Unión Mining District (SE Spain) and their interest for further revegetation purposes.

    PubMed

    Conesa, Héctor M; García, Gregorio; Faz, Angel; Arnaldos, Raquel

    2007-06-01

    Mine tailings are typical elements in post-mining landscapes which usually have high heavy metal contents and are affected by intensive erosion processes, above all in arid and semiarid areas. Revegetation of these sites is considered a low cost and suitable technology to effect surface stabilization. Spontaneous plant communities that colonize tailings in Southern Spain showed different behavior depending on the pH: in neutral tailings the plant communities were formed by less number of plant species than in acid tailings but they had less seasonal variations, showing a stable development. This spontaneous vegetation, that is adapted to metal toxicity and to drought, allows reducing air borne and water erosion, and may mitigate the spread of the contamination to the nearby areas.

  10. Cache Creek terrane entrapment: Oroclinal paradox within the Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Mihalynuk, Mitch G.; Nelson, Joanne; Diakow, Larry J.

    1994-06-01

    Exotic and far-traveled oceanic crustal rocks of the Cache Creek terrane (CC) are bordered by less exotic Quesnel (QN) and Stikine (ST) arc terranes to the east, north, and west. All of these terranes are enveloped by an arcuate belt of displaced continental margin rocks; the Kootenay (KO), Nisling (NS), and parts of the Yukon-Tanana (YTT) terranes, that have indirect ties to ancestral North America (NA). Initial 87Sr/86Sr isopleths conform to this arcuate pattern. Such a pattern of concentric belts presents a geological conundrum: How did the QN, ST, and CC come to be virtually enveloped by terranes with ties to NA? Past and current models that explain assembly of the Canadian Cordillera are deficient in their treatment of this problem. We propose that Early Mesozoic QN and ST were joined through their northern ends as two adjacent arc festoons that faced south toward the Cache Creek ocean (Panthalassa?). Oceanic plateau remnants within the CC today were transported from the Tethyan realm and collided with these arcs during subduction of the Cache Creek ocean. Counterclockwise oroclinal rotation of ST and NS terranes in the Late Triassic to Early Jurassic caused enclosure of the CC. Rotation continued until these terranes collided with QN in the Middle Jurassic. Paleomagnetic declination data provide support for this model in the form of large average anticlockwise rotations for Permian to Early Jurassic sites in ST but moderate clockwise rotations for sites in QN. Specific modern analogues for the Cordilleran orocline include the Yap trench, where the Caroline rise is colliding end-on with the Mariana Arc and the Banda Arc, located on the southeastern "tail" of the Asian plate, which is being deformed into a tight loop by interactions with the Australian and Pacific plates.

  11. Present-day geodynamics of the northern North American Cordillera

    NASA Astrophysics Data System (ADS)

    Finzel, Emily S.; Flesch, Lucy M.; Ridgway, Kenneth D.

    2014-10-01

    Diffuse continental deformation results from interactions at plate boundaries, buoyancy forces generated by gradients in gravitational potential energy, and loads applied to the base of the lithosphere. Using finite element models, we calculate a deviatoric stress field associated with buoyancy forces, and then perform an iterative inversion to calculate deviatoric stress fields associated with boundary forces in the northern North American Cordillera. Our results reveal the presence of two distinct geodynamic domains. In the outboard domain, approximately equal magnitudes of boundary and buoyancy forces can account for the observed deformation along the Aleutian megathrust. In contrast, large boundary forces related to subduction of the Pacific and Yakutat slabs dominate the force-balance in south-central Alaska and combine with relatively small buoyancy forces to reproduce the observed kinematic indicators. In the inboard domain, encompassed by interior and northern Alaska and western Canada, boundary and buoyancy forces alone cannot reproduce the observed deformation. Therefore, we infer that deviatoric stresses due to basal tractions from a deeper mantle convection cell contribute to surface deformation in the inboard domain. Low effective lithospheric viscosity in south-central Alaska and the balancing effect of an independent geodynamic system driven by basal tractions in northern Alaska combine to confine the anomalously large Yakutat-related boundary deviatoric stresses to south-central Alaska. Deviatoric stresses associated with flat-slab subduction of the Yakutat microplate are a factor of two greater than boundary force estimates for the Andean and Indian-Eurasian convergent margins, where buoyancy and boundary forces are roughly equal in magnitude and dominate the force-balance.

  12. Late Pleistocene glacial fluctuations in Cordillera Oriental, subtropical Andes

    NASA Astrophysics Data System (ADS)

    Martini, Mateo A.; Kaplan, Michael R.; Strelin, Jorge A.; Astini, Ricardo A.; Schaefer, Joerg M.; Caffee, Marc W.; Schwartz, Roseanne

    2017-09-01

    The behavior of subtropical glaciers during Middle to Late Pleistocene global glacial maxima and abrupt climate change events, specifically in Earth's most arid low-latitude regions, remains an outstanding problem in paleoclimatology. The present-day climate of Cordillera Oriental, in arid northwestern Argentina, is influenced by shifts in subtropical climate systems, including the South American Summer Monsoon. To understand better past glacier-subtropical climates during the global Last Glacial Maximum (LGM, 26.5-19 ka) and other time periods, we combined geomorphic features with forty-two precise 10Be ages on moraine boulders and reconstructed paleo-equilibrium line altitudes (ELA) at Nevado de Chañi (24°S) in the arid subtropical Andes. We found a major glacial expansion at ∼23 ± 1.6 ka, that is, during the global LGM. Additional glacial expansions are observed before the global LGM (at ∼52-39 ka), and after, at 15 ± 0.5 and 12 ± 0.6 ka. The ∼15 ka glacial event was found on both sides of Chañi and the ∼12 ka event is only recorded on the east side. Reconstructed ELAs of the former glaciers exhibit a rise from east to west that resembles the present subtropical climate trajectory from the Atlantic side of the continent; hence, we infer that this climate pattern must have been present in the past. Based on comparison with other low-latitude paleoclimate records, such as those from lakes and caves, we infer that both temperature and precipitation influenced past glacial occurrence in this sector of the arid Andes. Our findings also imply that abrupt deglacial climate events associated with the North Atlantic, specifically curtailed meridional overturning circulation and regional cooling, may have had attendant impacts on low subtropical Southern Hemisphere latitudes, including the climate systems that affect glacial activity around Nevado de Chañi.

  13. Mantle plume influence on the Neogene uplift and extension of the US western Cordillera?

    USGS Publications Warehouse

    Parsons, T.; Thompson, G.A.; Sleep, Norman H.

    1994-01-01

    Despite its highly extended and thinned crust, much of the western Cordillera in the United States is elevated more than 1km above sea level. Therefore, this region cannot be thought of as thick crust floating isostatically in a uniform mantle; rather, the lithospheric mantle and/or the upper asthenosphere must vary in thickness or density across the region. Utilizing crustal thickness and density constraints, the residual mass defcicit that must occur in the mantle lithosphere and asthenosphere beneath the western Cordillera was modelled. A major hot spot broke out during a complex series of Cenozoic tectonic events that included lithospheric thickening, back-arc extension, and transition from subduction to a transform plate boundary. It is suggested that many of the characteristics that make the western Cordillera unique among extensional provinces can be attributed to the mantle plume that created the Yellowstone hot spot. -Authors

  14. Glacier surface mass balance and freshwater runoff modeling for the entire Andes Cordillera

    NASA Astrophysics Data System (ADS)

    Mernild, Sebastian H.; Liston, Glen E.; Yde, Jacob C.

    2017-04-01

    Glacier surface mass balance (SMB) observations for the Andes Cordillera are limited and, therefore, estimates of the SMB contribution from South America to sea-level rise are highly uncertain. Here, we simulate meteorological, snow, glacier surface, and hydrological runoff conditions and trends for the Andes Cordillera (1979/80-2013/14), covering the tropical latitudes in the north down to the sub-polar latitudes in the far south, including the Northern Patagonia Ice Field (NPI) and Southern Patagonia Ice Field (SPI). SnowModel - a fully integrated energy balance, blowing-snow distribution, multi-layer snowpack, and runoff routing model - was used to simulate glacier SMBs for the Andes Cordillera. The Randolph Glacier Inventory and NASA Modern-Era Retrospective Analysis for Research and Applications products, downscaled in SnowModel, allowed us to conduct relatively high-resolution simulations. The simulated glacier SMBs were verified against independent directly-observed and satellite gravimetry and altimetry-derived SMB, indicating a good statistical agreement. For glaciers in the Andes Cordillera, the 35-year mean annual SMB was found to be -1.13 m water equivalent. For both NPI and SPI, the mean SMB was positive (where calving is the likely reason for explaining why geodetic estimates are negative). Further, the spatio-temporal freshwater river runoff patterns from individual basins, including their runoff magnitude and change, were simulated. For the Andes Cordillera rivers draining to the Pacific Ocean, 86% of the simulated runoff originated from rain, 12% from snowmelt, and 2% from ice melt, whereas, for example, for Chile, the water-source distribution was 69, 24, and 7%, respectively. Along the Andes Cordillera, the 35-year mean basin outlet-specific runoff (L s-1 km-2) showed a characteristic regional hourglass shape pattern with highest runoff in both Colombia and Ecuador and in Patagonia, and lowest runoff in the Atacama Desert area.

  15. Structure of the eastern Cordillera of Colombia: Implications for trap styles and regional tectonics

    SciTech Connect

    Dengo, C.A. ); Covey, M.C. )

    1993-08-01

    The northwest margin of South America has undergone multiple phases of compressional deformation beginning in the Late Cretaceous and culminating in the Pliocene-Pleistocene. The latest phases (Miocene to Pleistocene) of this deformation created the Eastern Cordillera of Colombia. Compressional structures in the Eastern Cordillera formed traps that have petroleum exploration potential; these are generally in the form of fault-bend and fault-propagation folds containing top-sealed reservoir and mature source rocks. Trap delineation, although difficult to achieve because of the poor seismic quality obtained in the region, can be accomplished by supplementing the seismic data with geometric analysis of surficial structures. 50 refs., 17 figs.

  16. Karst evolution in the Cordillera de la Sal (Atacama, Chili)

    NASA Astrophysics Data System (ADS)

    de Waele, J.; Forti, P.; Picotti, V.; Zini, L.; Cucchi, F.; Brook, G.

    2009-04-01

    Rock salt composed of halite is at least three orders of magnitude more soluble than limestone. Because of this very high solubility rock salt rarely crops out extensively at the surface and is readily dissolved leaving insoluble residue (mainly clays and marls). Rock salt can only survive at the surface where climate is extremely arid and normally displays a large set of typical solution morphologies similar to those developed on limestone. Solution of rock salt also leads to the formation of underground caves several km long. Close to the village of San Pedro de Atacama, North of the Salar de Atacama basin, there is an important NNE-SSW trending elongated anticlinal ridge composed of Oligo-Miocene evaporitic rocks known under the name Cordillera de la Sal. The thick salt beds of this ridge, even in this hyperarid climate (mean annual rainfall is below 20 mm/y and there may be no rain for several years), have been karstified by occasional rains and have a well developed surface karst geomorphology with extremely sharp rillenkarren often isolating salt pinnacles of up to 15 m in height. During the past 10 years interesting salt caves have been discovered in these halite beds and a detailed morphological study has been carried out both at the surface and in the most important caves with the aim of understanding the mechanisms responsible for their formation and evolution. Sixteen wood and bone fragments from the ceilings of caves and from diamictons in passages have been AMS radiocarbon dated, allowing us to determine when the cave systems formed and when the major sediment units were emplaced. In fact, cave formation appears to have been very rapid, with development of huge cave passages in salt (more than 10 m wide and 30 m high) in less than 2,000 years. Moreover, detailed surveys of cave morphology (e.g. meanders, erosion benches) and sediments (diamictons) suggest that the caves were formed by short-lived flash floods, probably produced by single extreme

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

    USGS Publications Warehouse

    McLaughlin, Donald H.

    1972-01-01

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

  18. Population Declines of Mountain Coqui (Eleutherodactylus portoricensis) in the Cordillera Central of Puerto Rico

    PubMed Central

    Barker, Brittany S.; Ríos-Franceschi, Alejandro

    2014-01-01

    The Mountain Coqui (Eleutherodactylus portoricensis) is a frog endemic to montane rainforests in the Cordillera Central and Luquillo Mountains of Puerto Rico. Classified as endangered by the IUCN Red List and as vulnerable by the Department of Natural and Environmental Resources of Puerto Rico, this species has undergone considerable decline in the Luquillo Mountains. To evaluate the population status of E. portoricensis across its entire range, we conducted ~87 hours of surveys at 18 historical localities and 25 additional localities that we considered suitable for this species. We generated occupancy models to estimate the probability of occurrence at surveyed sites and to identify geographic and climatic factors affecting site occupancy. We also constructed a suitability map to visualize population status in relation to the presence of land cover at elevations where the species has been documented, and determined the dates when populations were last detected at historical localities. Eleutherodactylus portoricensis was detected at 14 of 43 localities, including 10 of 18 historical localities, but it was not detected at any localities west of Aibonito (western Cordillera Central). Occupancy models estimated the probability of occurrence for localities in the western Cordillera Central as zero. Site occupancy was positively associated with montane cloud forest, and negatively associated with the western Cordillera Central, maximum temperature, and precipitation seasonality. The suitability map suggests that declines have occurred despite the presence of suitable habitat. We suggest upgrading the extinction risk of E. portoricensis and potentially developing a captive breeding program for this species. PMID:25685250

  19. Stress field evolution above the Peruvian flat-slab (Cordillera Blanca, northern Peru)

    NASA Astrophysics Data System (ADS)

    Margirier, A.; Audin, L.; Robert, X.; Pêcher, A.; Schwartz, S.

    2017-08-01

    In subduction settings, the tectonic regime of the overriding plate is closely related to the geometry of the subducting plate. Flat-slab segments are supposed to increase coupling at the plate interface in the Andes, resulting in an increase and eastward migration of the shortening in the overriding plate. Above the Peruvian flat-slab, a 200 km-long normal fault trend parallel to the range and delimits the western flank of the Cordillera Blanca. In a context of flat subduction, expected to produce shortening, the presence of the Cordillera Blanca normal fault (CBNF) is surprising. We performed a systematic inversion of striated fault planes in the Cordillera Blanca region to better characterize the stress field above the Peruvian flat-slab. It evidences the succession of different tectonic regimes. NE-SW extension is predominant in most of the sites indicating a regional extension. We suggest that the Peruvian flat-slab trigger extension in the Western Cordillera while the shortening migrated eastward. Finally, we propose that flat-slab segments do not increase the coupling at the trench neither the shortening in the overriding plate but only favor shortening migration backward. However, the stress field of the overriding plate arises from the evolution of plate interface properties through time due to bathymetric anomaly migration.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  1. Gravity sliding, thrusting, and petroleum traps in the Magdalena Basins and Cordillera Orientale, Colombia

    SciTech Connect

    Jones, P.B. )

    1993-02-01

    Major gravity slides on flanks of mountain belts can be misinterpreted as tectonic thrusts. They occur as synclines ([open quotes]fauteuils glisses[close quotes]) striking sub-parallel to dip slopes of major uplifts, overlie low-angle listric thrusts which pass upslope into listric or bedding-parallel normal faults, and may be associated with gravity-driven buried thrust fronts. The Nuevo Mondo syncline, underlain by the La Salinas thrust, and similar synclines along the east side of the Magdalena valley are interpreted as [open quotes]fauteuils glisses[close quotes], whose occurrence at the edge of the Cordillera Orientale creates an illusion of westward thrusting. Minor faults, formerly interpreted as east-dipping reverse faults along the west edge of the Cordillera Orientale are too small to have uplifted the Cordillera or to be correlatable with the major thrusts beneath synclines. They are reinterpreted as major west-dipping parallel faults, pass downslope westward beneath the synclines and/or into blind imbricate thrust structures. The Magdalena basins contain attractive east-verging tectonic thrust traps for hydrocarbons, and less attractive post-tectonic west-verging thrust traps formed by sliding down the east flank of the basin. Interpretation of these structures as post-deformational features allows modeling of the Cordillera Orientale as an overthrust sheet about 10 km thick that moved over 160 km southeastward. Its ramp underlies the east flank of the Magdalena basins. Its buried thrust front marks the edge of the Llanos basin.

  2. Exhumation of the Cordillera Blanca batholith (Peruvian Andes) constrained by amphibole barometry and low-temperature thermochronology modelling

    NASA Astrophysics Data System (ADS)

    Margirier, Audrey; Audin, Laurence; Robert, Xavier; Herman, Frédéric; Ganne, Jérôme; Schwartz, Stéphane

    2017-04-01

    The Cordillera Blanca batholith forms the highest Peruvian summits and builds the footwall of the Cordillera Blanca normal fault (CBNF). Even if several models have been proposed, the processes driving both the exhumation of the Cordillera Blanca and extensional deformation along the CBNF are still debated. We coupled barometric and thermochronologic data to quantify the emplacement and exhumation history of the Cordillera Blanca batholith from the late Miocene to present. Based on new thermobarometry data and a compilation of crystallization ages in the Cordillera Blanca batholith, we propose that the batholith was emplaced at a depth of 3 km in successive sills from 12 to 5 Ma. Close to the CBNF, the younger rocks that are emplaced the deepest (i.e., 6 km) are exposed at the surface, suggesting post 5 Ma tilting. In addition, a formal inversion of the barometric and thermochronologic data (apatite fission-track and apatite (U-Th)/He) indicates an increase of the exhumation rates in the Cordillera Blanca during the Quaternary. The higher predicted exhumation rates correlate with areas of high relief suggesting that Quaternary valley carving by glaciations have a significant impact on the latest stage of the Cordillera Blanca exhumation (2-0 Ma).

  3. Cenozoic contractional reactivation of Mesozoic extensional structures in the Eastern Cordillera of Colombia

    NASA Astrophysics Data System (ADS)

    Mora, AndréS.; Parra, Mauricio; Strecker, Manfred R.; Kammer, Andreas; Dimaté, Cristina; RodríGuez, Fernando

    2006-04-01

    The Eastern Cordillera of Colombia is key to understanding the role of inherited basement anisotropies in the evolution of active noncollisional mountain belts. In particular, the Rio Blanco-Guatiquía region of the Eastern Cordillera is exemplary in displaying a variety of phenomena that document the importance of the orientation, geometry, and segmentation of preorogenic anisotropies. We document the first unambiguous evidence that extensional basement structures played an important role in determining the locus of deformation during contractional reactivation in the Eastern Cordillera. Detailed structural field mapping and analysis of industry seismic reflection profiles have helped to identify the inherited San Juanito, Naranjal, and Servitá normal faults and associated transfer faults as important structures that were inverted during the Cenozoic Andean orogeny. Apparently, the more internal faults in the former rift basin were not properly oriented for an efficient reactivation in contraction. However, these faults have a fundamental role as strain risers, as folding is concentrated west of them. In contrast, reactivated normal faults such as the more external Servitá fault are responsible for uplifting the eastern flank of the Eastern Cordillera. In addition, these structures are adjacent and intimately linked to the development of thin-skinned faults farther east. In part, the superimposed compression in this prestrained extensional region is compensated by lateral escape. The dominant presence of basement involved buckling and thrusting, and the restricted development of thin-skinned thrusting in this inversion orogen makes the Eastern Cordillera a close analog to the intraplate Atlas Mountains of Morocco and other inverted sectors of the Andean orogen farther south.

  4. Coupled measurements of δ18O and δD of hydration water and salinity of fluid inclusions in gypsum from the Messinian Yesares Member, Sorbas Basin (SE Spain)

    NASA Astrophysics Data System (ADS)

    Evans, Nicholas P.; Turchyn, Alexandra V.; Gázquez, Fernando; Bontognali, Tomaso R. R.; Chapman, Hazel J.; Hodell, David A.

    2015-11-01

    We studied one cycle (Cycle 6) of gypsum-marl deposition from the Messinian Yesares Member in Sorbas Basin, Spain. The objective was to reconstruct the changing environment of deposition and its relation to astronomically-forced climate change. The δ18O and δD of gypsum hydration water (CaSO4 • 2H2O) and salinity of fluid inclusions were measured in the same samples to test if they record the composition of the mother fluid from which gypsum was precipitated. Water isotopes are highly correlated with fluid inclusion salinity suggesting the hydration water has not exchanged after formation. The relatively low water isotope values and fluid inclusion salinities indicate a significant influence of meteoric water, whereas δ34S, δ18OSO4 and 87Sr/86Sr support a dominant marine origin for the gypsum deposits. The discrepancy between water and elemental isotope signatures can be reconciled if meteoric water dissolved previously deposited marine sulfates supplying calcium and sulfate ions to the basin which maintained gypsum saturation. This recycling process accounts for the marine δ34S, δ18OSO4 and 87Sr/86Sr signatures, whereas the low δ18O and δD values of gypsum hydration water and fluid inclusion salinities reflect the influence of freshwater. The cyclic deposition of gypsum and marl in the Yesares Member has previously been interpreted to reflect changing climate related to Earth's precession cycle. We demonstrate that the δ18O, δD and salinity of the parent brine increased from low values at the base of the cycle to a maximum in the massive gypsum palisade, and decreased again to lower values in the supercones at the top of the cycle. This pattern, together with changes in mineralogy (calcite-dolomite-gypsum), is consistent with a precession-driven change in climate with wettest conditions (summer insolation maxima) associated with the base of the calcium carbonate marls and driest conditions (summer insolation minima) during formation of the gypsum

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  6. Summary terrane, mineral deposit, and metallogenic belt maps of the Russian Far East, Alaska, and the Canadian Cordillera

    USGS Publications Warehouse

    Nokleberg, Warren J.; West, Timothy D.; Dawson, Kenneth M.; Shpikerman, Vladimir I.; Bundtzen, Thomas K.; Parfenov, Leonid M.; Monger, James W.; Ratkin, Vladimir V.; Baranov, Boris V.; Byalobzhesky, Stanislauv G.; Diggles, Michael F.; Eremin, Roman A.; Fujita, Kazuya; Gordey, Steven P.; Gorodinskiy, Mary E.; Goryachev, Nikolai A.; Feeney, Tracey D.; Frolov, Yuri F.; Grantz, Arthur; Khanchuk, Alexander I.; Koch, Richard D.; Natal'in, Boris A.; Natapov, Lev M.; Norton, Ian O.; Patton, William W.; Plafker, George; Pozdeev, Anany I.; Rozenblum, Ilya S.; Scholl, David W.; Sokolov, Sergei D.; Sosunov, Gleb M.; Stone, David B.; Tabor, Rowland W.; Tsukanov, Nickolai V.; Vallier, Tracy L.

    1998-01-01

    This report is part of a project on the major mineral deposits, metallogenesis, and tectonics of the Russian Far East, Alaska, and the Canadian Cordillera. The project is to provide critical information for collaborators and customers on bedrock geology and geophysics, tectonics, major metalliferous mineral resources, metallogenic patterns, and crustal origin and evolution of mineralizing systems for the Russian Far East, Alaska, and the Canadian Cordillera.

  7. Timing of hydrocarbon maturation and trap formation in the Cordillera Oriental and adjacent petroleum provinces of Colombia

    SciTech Connect

    Schamel, S.; Richardson, A.; Carlos, A.A.P.

    1996-08-01

    The timing of hydrocarbon generation relative to the closure of migration pathways and trap formation is key to characterization of the petroleum systems of the Cordillera Oriental and the prolific petroleum provinces of the Llanos and Magdalena. The exceptionally thick and organic rich Cretaceous source rock successions of the Cordillera Oriental had the potential to have generated vast quantities of liquid hydrocarbons. Yet due to unfavorable timing of hydrocarbon maturation vs. regional deformation, only a small portion of this oil may have migrated into traps beyond the limits of the Cordillera Oriental. Maturation modeling based on detailed stratigraphic and structural data for sites in the Cordillera Oriental, Llanos, and the Middle and Upper Magdalena basins reveal the essential temporal features of the petroleum system. Virtually all of the Cretaceous source rock succession was generating liquid hydrocarbons in the Late Cretaceous and Paleocene, long before the development of the main structural traps within and along the foothills belts marginal to the Cordillera Oriental. Only in the northeast quarter and extreme south of the Cordillera Oriental and in the deeper parts of the flanking basins was oil being generated simultaneous with trap formation. The maturation modeling serves as a basis for understanding the known distribution of oil pools and a guide to future discoveries.

  8. Using nanogranite and glassy inclusions to unravel anatexis in the crustal footwall of the Ronda peridotites (Betic Cordillera, S Spain)

    NASA Astrophysics Data System (ADS)

    Bartoli, Omar; Acosta-Vigil, Antonio; Cesare, Bernardo; Remusat, Laurent; Tajčmanová, Lucie; Wälle, Markus; Heinrich, Christoph; Poli, Stefano; Bodnar, Robert J.

    2015-04-01

    The application of melt inclusion (MI) studies to migmatites and granulites is a recent, small-scale approach to a better understanding of melting in the continental crust [1]. Being trapped by growing peritectic phases at suprasolidus conditions, these MI represent a window into the pre-peak anatectic history of partially melted terranes, and may provide a wealth of microstructural and compositional information on crustal anatexis [2, 3, 4]. The crustal footwall of the Ronda peridotites consists of an inverted metamorphic sequence with migmatites and mylonites at the top. Mylonites represent strongly deformed former diatexites. To shed light on the nature and mechanisms of melting in the migmatites of the Ojén traverse, a detailed microstructural and geochemical study has been conducted on primary 2-10 µm MI hosted in peritectic garnet of i) metatexites at the bottom of the migmatitic sequence and ii) mylonitic former diatexites close to the contact with the mantle rocks. Both metatexites and mylonites have compositions corresponding to peraluminous greywackes. Phase equilibria modeling shows P-T conditions of equilibration of 4.5-5 kbar and 660-700 °C, and of 820-830 °C and 5.5-6.0 kbar for metatexites and mylonites, respectively. Clusters of MI in the metatexites are rounded and preferentially located at the core of small garnet crystals, whereas these clusters may have a sigmoidal to spiral-like shape in garnets of mylonites. MI show a variable degree of crystallization ranging from totally glassy to fully crystallized (i.e., nanogranites), consisting of Qtz+Pl+Kfs+Bt+Ms aggregates (often modal Kfs > Pl in mylonites). Piston cylinder remelting experiments led to the complete rehomogenization of nanogranites in metatexites at the conditions inferred for anatexis: 700 °C and 5 kbar. Rehomogenized nanogranites in metatexites and glassy MI in mylonites are all leucogranitic, although generally plot away from minimum melt compositions. Systematic compositional variations have been observed between MI in metatexites and mylonites. MI in metatexites show higher amounts of H2O and Na2O/K2O ratios, lower FeO content, and higher concentrations of those trace elements controlled by feldspars: Sr, Ba. MI in mylonites have higher concentrations of trace elements controlled by Bt (Cs, Rb and FRTE e.g. Zn, Sc) and accessory minerals (HFSE e.g. Zr, U, Th, and LREE). The compositions of MI in metatexites and mylonites are interpreted to record the composition of the anatectic melts produced from a peraluminous greywacke 1) on, and immediately after crossing, the fluid-saturated solidus of this metasedimentary rock, and 2) during syn-kinematic anatexis via biotite dehydration melting at increasing temperature, respectively. [1] Cesare et al. (2009) Geology, 37, 627-630. [2] Bartoli et al. (2013) Geology, 41, 115-118. [3] Bartoli et al. (2014) EPSL, 395, 281-290. [4] Acosta-Vigil et al. (2010) JPetrol 51, 785-821.

  9. Basin development and tectonic history of the Llanos Basin, Eastern Cordillera, and Middle Magdalena Valley, Colombia

    SciTech Connect

    Cooper, M.A.; Addison, F.T.; Alvarez, R.

    1995-10-01

    The Middle Magdalena Valley, Eastern Cordillera, and Llanos basin constituted a major regional sedimentary basin from the Triassic to the middle Miocene. Basin development began during the Triassic to the earliest Cretaceous with a synrift megasequence related to the separation of North and South America in the proto-Caribbean. The synrift megasequence began with deposition in a continental environment that became paralic and shallow marine in the Early Cretaceous. Basin development continued into the Cretaceous in a back-arc setting east of the Andean subduction zone. The back-arc megasequence was dominated by shallow-marine sedimentation and produced an excellent regional source rock during the Turonian-Coniacian. Marine deposition was abruptly terminated during the early Maastrichtian due to the final accretion of the Western Cordillera.

  10. Origins and movement of fluids during deformation and metamorphism in the canadian cordillera.

    PubMed

    Nesbitt, B E; Muehlenbachs, K

    1989-08-18

    Stable isotope data from quartz veins in the Canadian Cordillera indicate that crustal fluids were heterogeneous in terms of sources and flow paths during Mesozoic-Cenozoic metamorphism and deformation. In regions of strike-slip and extensional faulting, the fluid regime to depths of at least 15 kilometers was dominated by convected, chemically evolved meteoric water. In contrast, in thrust faulted regions, the fluid regime was dominated by fluids derived from metamorphic devolatilization reactions. Deep convection of meteoric water implies that fluid pressures are hydrostatic in such systems not lithostatic, as had been commonly assumed. The occurrence of significantly lower fluid pressures would necessitate reevaluation of the manner in which metamorphic phase equilibria and stress relations in the crust are modeled. In addition, this study indicates that mesothermal gold deposits in the Canadian Cordillera are a product of the meteoric water convection process.

  11. The Columbia Plateau Revealed; Low Temperature Thermochronology Across the Canadian Cordillera and Links to Lithospheric Delamination.

    NASA Astrophysics Data System (ADS)

    Guest, B.; Bacque, D.; Miles, N.; Stockli, D. F.

    2014-12-01

    Active deformation and mountain building in the Canadian Cordillera ceased in the Paleogene, a period during which this orogen was among the highest on earth. The present morphology, relief and altitude of the mountains and the foothills in the adjacent foreland belt are the result of a feedback relationship between erosion and isostatic compensation. Our low temperature thermochronology data (U-Th/He ages on zircon and apatite) were collected from 5 sample-transects spanning the Intermontane, Omineca, Foreland, and Foothills belts along a Jasper-Vancouver transect. The data show rapid cooling (>15℃/Ma) from >180℃ to <70℃ in the interior belts to the west of the Rocky Mountain Trench (RMT) during the Eocene (56 - 33 Ma). In the Foreland and Foothills belts to the east of the RMT the data show modest cooling (~4℃/Ma) during the latest Cretaceous to Early Eocene (~80Ma - 55 Ma) followed by rapid cooling (~15℃/Ma) between ~55 Ma and ~45 Ma transitioning to slower cooling (~1℃/Ma) after 45 Ma. This cooling pattern is consistent with rapid regional uplift and exhumation across the interior belts of the Cordillera during a regional transition from contraction to extension in the early to middle Eocene. At the same time in the Foreland and Foothills belts, during a period of accelerated cooling, contraction was continuing. The combination of rapid exhumation and extension in the interior belts and rapid exhumation and contraction in the Foreland and Foothills belts is similar to what is observed around the Altiplano and Tibetan plateaus. This suggests that the Canadian Cordillera is a fossil plateau (Columbia Plateau) that formed in the Eocene. The lack of a mantle lithosphere beneath the interior belts of the Canadian Cordillera (west of the RMT) and the regional extent of rapid exhumation suggests that the Columbia Plateau formed in response to a large-scale lithosphere removal event; possibly wholesale delamination.

  12. The basement of the Eastern Cordillera, Colombia: An allochthonous terrane in northwestern South America

    NASA Astrophysics Data System (ADS)

    Forero Suarez, A.

    The fault system of the Borde Llanero of Colombia represents the limit between two early Paleozoic geologic provinces: the Guiana Shield (Gondwana) to the east, and an allochthonous terrane — formerly a piece of the North American continent — to the west. The Baudó Range, the Western Cordillera, and the western flank of the Central Cordillera are the result of post-Jurassic accretion. In contrast the pre-Emsian metamorphic rocks of the eastern flank of the Central Cordillera, of the Eastern Cordillera of Colombia, and of the Mérida Andes correspond to an allochthonous terrane that was accreted to the north-western continental border of South America during the collision between North America and Gondwana in Silurian-Early Devonian times. Geochronologic and petrographic data indicate the presence of the Grenvillian granulite belt, represented by the Garzón-Sierra Nevada de Santa Marta belt. This belt is separated from the Guiana Shield by a magmatic tract which is parallel to the Borde Llanero of Venezuela and Colombia. The late Paleozoic regional metamorphism in the Northern Andes of Colombia occurred during Late Silurian-Early Devonian times. Since the late Emsian, a sedimentary cycle was initiated on this allochthonous basement. The faunal records of northwestern South America and the North American continent are indistinguishable for that time. This similarity clearly shows that both northwestern South America and the North American regions of the Appalachians and New Mexico belong to the same paleobiogeographic province. The faunal communication in this case supports the idea of the immediate neighborhood of the two continents.

  13. Regional variations of mantle anisotropy across the Canadian Cordillera from teleseismic shear-wave splitting

    NASA Astrophysics Data System (ADS)

    Zandt, G.; Frassetto, A. M.; Cassidy, J. F.; Bostock, M. G.

    2009-12-01

    The Canadian Cordillera overlies a slab window developed after the cessation of ocean-continent subduction during the mid-Cenozoic. Widespread basaltic volcanism occurring over the last 20 million years throughout the Cordillera appears geochemically depleted when compared to magmas generated within continental lithosphere. Characterizing seismic anisotropy constrains ongoing deformation in the upper mantle beneath the Cordillera and provides an opportunity to investigate the potential source of these magmas. We use the rotation correlation, eigenvalue minimization, and energy minimization methods through the Splitlab software package to analyze teleseismic SKS phases recorded by seismometers deployed as part of the Batholiths and Nechako Experiments and increased regional monitoring. Splitting measurements collected across the central British Columbia, southeastern Alaska, and the southern Yukon reveal regional patterns in seismic anisotropy. Stations closest to the southern Denali and Queen Charlotte faults show large splitting times (1.5-2.0 s) along orientations consistent with the dextral transform between the North American and Pacific plates. Stations within the coastal region show generally null patterns. A robust pattern of east-west oriented splitting across the central Coast Mountains Batholith and Interior Plateau cannot be easily explained in terms of lithospheric structural fabric, and its regional coherency and magnitude (up to 1.5 s) indicates that a significant amount of anisotropy occurs within asthenospheric mantle. When combined with other geophysical and geochemical constraints, the pattern of anisotropy suggests upwelling and lateral flow of asthenosphere around the northern edge of the subducting Juan de Fuca slab. Asthenospheric flow into a complex slab window north of the Juan de Fuca plate would explain the lack of splitting seen in certain regions of the Cordillera and provide a mechanism for fueling the post-subduction volcanism observed

  14. Oblique transpression in the western thrust front of the Colombian Eastern Cordillera

    NASA Astrophysics Data System (ADS)

    Acosta, J.; Lonergan, L.; Coward, M. P.

    2004-11-01

    New kinematic data reveal that the main faults of the western foothills of the Colombian Eastern Cordillera are a series of left-lateral to oblique thrusts that are offset by steeply dipping, northwest-trending, left-lateral, strike-slip faults. Kinematic data were collected from the main structures that dominate the 350-km length of the western foothills of the Eastern Cordillera, north of Bogota (La Salina-Bituima, Cambrás, Dos Hermanos-Alto del Trigo, and Bucaramanga faults). These data indicate that transpression is responsible for the Cenozoic formation of the folds and thrusts that deform the Mesozoic and Cenozoic sedimentary sequences of the Middle Magdalena Valley. Kinematic and structural data suggest that the La Salina-Bituima fault changed from a reverse fault to a fault with a left-lateral, strike-slip sense of displacement during middle to late Miocene times. As it propagated, a transpressive zone was generated in the western foothills of the Eastern Cordillera, with the development of arcuate, oblique-reverse secondary faults on the leading edge of the Magdalena basin (e.g. Cambrás, Dos Hermanos). This development implies that during the Neogene (?), the tectonics of the western foothills were dominated by nonplanar deformation with shortening accompanied by significant left-lateral, strike-slip displacements. These new data indicate that the oblique convergence vector imposed by convergence among the Nazca, Caribbean, and South American plates is not fully partitioned in space but instead must be distributed in a diffuse zone of transpressional deformation along the western margin of the Eastern Cordillera and its associated foreland basin.

  15. Source terrains and diagenetic imprints of Cretaceous marine rocks of the Cordillera Oriental, Colombia

    SciTech Connect

    Segall, M.P.; Allen, R.B. ); Rubiano, J.; Sarmiento, L. )

    1993-02-01

    Cretaceous marine rocks of the western Cordillera Oriental of Colombia are exposed in stratigraphic sections which reveal multiple source terrains and variable diagenetic histories that were imposed by later thrusting XRD and petrographic analyses indicate that earliest Cretaceous rocks were derived from a nearly plutonic source (Triassic-Jurassic Ibague Batholith of the Cordillera Central) which provided feldspathic lithic fragments and clay-sized illite. High smectite concentrations in the overlying Hauterivian-Barremian strata reflect contemporaneous volcanism, possibly in the Cordillera Central. This signal decreased upsection to the upper Aptian, where detrital clays (kaolinite, chlorite, feldspar, amphibole) indicate a shift to a cratonic source, probably the Guayana Shield. Cratonic detrital input continues into the Turonian-Coniacian and is accompanies by high concentrations of smectite representing another period of volcanic activity. Later tectonic activity divided the area into two regions, each with unique diagenetic signatures. Three primary clastic sources are inferred for the section east of the thrust belt, however, the mineral assemblage is masked by later diagenesis. Sediments within the thrust belt show greater variability in the relative abundance of mineral assemblages and more poorly crystallized illite than occurs to the east of the thrust section. The preservation of much of the original mineralogic components within the thrust section indicates that these sediments have experienced only limited diagenetic overprinting as a result of a relatively short burial history. These contrasting signatures have important implications for hydrocarbon maturation within Cretaceous source rocks in a structurally complex region.

  16. Andean-scale highlands in the Late Cretaceous Cordillera of the North American western margin

    NASA Astrophysics Data System (ADS)

    Sewall, Jacob O.; Fricke, Henry C.

    2013-01-01

    From the Late Jurassic through the Cretaceous, collision between the North American and Farallon plates drove extensive thin-skinned thrusting and crustal shortening that resulted in substantial relief in the North American Cordillera. The elevation history of this region is tightly linked to the tectonic, climatic and landscape evolution of western North America but is not well constrained. Here we use an atmospheric general circulation model with integrated oxygen isotope tracers (isoCAM3) to predict how isotope ratios of precipitation would change along the North American Cordillera as the mean elevation of orogenic highlands increased from 1200 m to 3975 m. With increases in mean elevation, highland temperatures fall, monsoonal circulation along the eastern front of the Cordillera is enhanced, and wet season (generally spring and summer) precipitation increases. Simulated oxygen isotopic ratios in that precipitation are compared to those obtained from geologic materials (e.g. fossil bivalves, authigenic minerals). Quantification of match between model and data-derived δ18O values suggests that during the Late Cretaceous, the best approximation of regional paleoelevation in western North America is a large orogen on the scale of the modern Andes Mountains with a mean elevation approaching 4000 m and a north-south extent of at least 15° of latitude.

  17. Cretaceous and Tertiary terrane accretion in the Cordillera Occidental of the Andes of Ecuador

    NASA Astrophysics Data System (ADS)

    Hughes, Richard A.; Pilatasig, Luis F.

    2002-02-01

    New field, geochronological, geochemical and biostratigraphical data indicate that the central and northern parts of the Cordillera Occidental of the Andes of Ecuador comprise two terranes. The older (Pallatanga) terrane consists of an early to late (?) Cretaceous oceanic plateau suite, late Cretaceous marine turbidites derived from an unknown basaltic to andesitic volcanic source, and a tectonic mélange of probable late Cretaceous age. The younger (Macuchi) terrane consists of a volcanosedimentary island arc sequence, derived from a basaltic to andesitic source. A previously unidentified, regionally important dextral shear zone named the Chimbo-Toachi shear zone separates the two terranes. Regional evidence suggests that the Pallatanga terrane was accreted to the continental margin (the already accreted Cordillera Real) in Campanian times, producing a tectonic mélange in the suture zone. The Macuchi terrane was accreted to the Pallatanga terrane along the Chimbo-Toachi shear zone during the late Eocene, probably in a dextral shear regime. The correlation of Cretaceous rocks and accretionary events in the Cordillera Occidental of Ecuador and Colombia remains problematical, but the late Eocene event is recognised along the northern Andean margin.

  18. The Middle Jurassic radiolarites and pelagic limestones of the Nieves unit (Rondaide Complex, Betic Cordillera): basin starvation in a rifted marginal slope of the western Tethys

    NASA Astrophysics Data System (ADS)

    O'Dogherty, Luis; Martín-Algarra, Agustín; Gursky, Hans-Jürgen; Aguado, Roque

    2001-11-01

    Middle Jurassic radiolarites and associated pelagic limestones occur in the Rondaide Nieves unit of the Betic Cordillera, southern Spain. The Rondaide Mesozoic includes: (a) a thick succession of Triassic platform carbonates, comparable to the Alpine Hauptdolomit and Kössen facies; (b) Lower Jurassic pelagic limestones comparable to the Alpine Hierlatz and Adnet facies; (c) the Middle Jurassic Parauta Radiolarite Formation, described herein; and (d) a thin Upper Jurassic-Cretaceous condensed limestone succession. The Parauta Radiolarite Formation and associated limestones were studied with respect to stratigraphy, petrography, micropalaeontology (radiolarians, calcareous nanno- and microfossils) and facies. Radiolarite sedimentation occurred in the Middle Bathonian in a restricted and dysoxic deep Nieves basin, perched in the distal zone of a continental margin fringing the Tethyan ocean. This margin was adjacent to a young narrow oceanic basin between the South-Iberian margin and a continental block called Mesomediterranean Terrane. The Nieves basin was part of a marine corridor between the Proto-Atlantic and Piedmont-Ligurian basins of the Alpine Tethys. The regional tectonic position, the stratigraphical evolution since the Triassic, the age and the nature of the Mesozoic facies and the palaeogeographic relations to adjacent domains show striking analogies between the Betic Rondaide margin and coeval units of the Alps.

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    This study aims at quantifying the 3-D variability in lithosphere strength of the south-eastern Canadian Cordillera and adjacent craton to the east. Strength is calculated in a forward manner, starting from rheological laws of brittle and ductile deformation. The work flow calculates a temperature model based on a multi-layer compositional model and subsequently estimates the strength distribution from both the compositional and temperature models. The temperature modeling involves numerical inversion and cubic spline algorithms which enable to impose boundary conditions that account better for strong lateral variations in lithosphere thickness and lateral heat flow. This addresses the lithosphere structure between the Canadian Cordillera and craton. The Canadian Cordillera is marked by a hot and thin lithosphere of ~ 60 km thickness that stands in contrast to a cold and thick craton of ~ 170 km thickness to the east, which consequently results in pronounced changes in bulk lithosphere strength. The high surface heat flow of the Cordillera interior and its contrast with the Foreland Basin can be reproduced by temperature models that combine elevated mantle heat flow due to the thin lithosphere and higher crustal heat production from magmatic intrusions. A series of rheological models, which examines the role of different temperature input models, composition and strain rate, shows that the first-order strength pattern is persistent. For the hot Canadian Cordillera, strength resides for > 80% in the upper crust and with integrated lithosphere strength of 2.0-3.5ṡ106 MPaṡm. For the cold craton, the upper mantle provides > 75% of the integrated strength with values of 4.0-8.0ṡ106 MPaṡm for the crust and 20-65ṡ106 MPaṡm for the lithosphere. Effective elastic thickness is estimated between 5 and 15 km for the Cordillera and 40-80 km for the craton. This illustrates the Cordillera to craton transition as a prominent rheological feature for upper mantle flow

  20. Solar Power, Seville, Spain

    NASA Image and Video Library

    2009-09-01

    The world largest solar power tower recently began operating outside Seville, Spain -- and it marks a historic moment in the saga of renewable energy. This image was acquired by NASA Terra spacecraft.

  1. Rio Tinto, Spain

    NASA Image and Video Library

    2010-09-02

    The Advanced Spaceborne Thermal Emission and Reflection Radiometer instrument aboard NASA Terra spacecraft captured this image of the Rio Tinto river in southwestern Spain which originates in the Sierra Morena mountains of Andalusia.

  2. Alternative models for Late Jurassic and Early Cretaceous paleogeography of the western Cordillera, California to SE Alaska

    SciTech Connect

    Cowan, D.S. . Geological Sciences)

    1993-04-01

    The Franciscan-Great Valley-Sierran triad is indisputable evidence for late Mesozoic, west-facing subduction along the California sector of the N. American margin. In the northwestern sector (N of 48[degree]N), however, neither the configuration of plate boundaries, nor the paleogeographic disposition of the Insular and Intermontane superterranes, is confidently established. Models divide into two groups. One set, based entirely on geologic evidence such as the age and nature of deformational events, or putative stratigraphic links among terranes, places the two superterranes exclusively to the north of the Franciscan-Sierran system from 150 to 90 Ma. These hypotheses, which ignore or reject paleomagnetic data from mid-Cretaceous rocks, yield a paleogeography not too different from today's, but they are incompatible with the Franciscan and Great Valley rocks caught between the superterranes in the mid-Cretaceous San Juan-Cascade thrust system. An alternative model fully respecting paleomagnetic data from mid-Cretaceous rocks with paleohorizontal control restores most of the Intermontane superterrane [approximately]1,200 km south of its expected (i.e. present) latitudinal position with respect to North America, and the Insular superterrane [approximately]2,900 km south, at 95--105 Ma. The mid-Cretaceous thrust system along the eastern margin of the Insular superterrane records the collision of Wrangellia et al. with the southern continuation of the Franciscan subduction zone. The thrust system, a silver of hanging wall, and the Insular superterrane were all subsequently translated > 2,500 km northward by post-80, pre-60 Ma coast-parallel dextral slip, accommodated on the proto-Pasayten and proto-Yalakom faults, and along or near the Coast Range shear zone.

  3. Lithofacies control in detrital zircon provenance studies: Insights from the Cretaceous Methow basin, southern Canadian Cordillera

    USGS Publications Warehouse

    DeGraaff-Surpless, K.; Mahoney, J.B.; Wooden, J.L.; McWilliams, M.O.

    2003-01-01

    High-frequency sampling for detrital zircon analysis can provide a detailed record of fine-scale basin evolution by revealing the temporal and spatial variability of detrital zircon ages within clastic sedimentary successions. This investigation employed detailed sampling of two sedimentary successions in the Methow/Methow-Tyaughton basin of the southern Canadian Cordillera to characterize the heterogeneity of detrital zircon signatures within single lithofacies and assess the applicability of detrital zircon analysis in distinguishing fine-scale provenance changes not apparent in lithologic analysis of the strata. The Methow/Methow-Tyaughton basin contains two distinct stratigraphic sequences of middle Albian to Santonian clastic sedimentary rocks: submarine-fan deposits of the Harts Pass Formation/Jackass Mountain Group and fluvial deposits of the Winthrop Formation. Although both stratigraphic sequences displayed consistent ranges in detrital zircon ages on a broad scale, detailed sampling within each succession revealed heterogeneity in the detrital zircon age distributions that was systematic and predictable in the turbidite succession but unpredictable in the fluvial succession. These results suggest that a high-density sampling approach permits interpretation of finescale changes within a lithologically uniform turbiditic sedimentary succession, but heterogeneity within fluvial systems may be too large and unpredictable to permit accurate fine-scale characterization of the evolution of source regions. The robust composite detrital zircon age signature developed for these two successions permits comparison of the Methow/Methow-Tyaughton basin age signature with known plutonic source-rock ages from major plutonic belts throughout the Cretaceous North American margin. The Methow/Methow-Tyaughton basin detrital zircon age signature matches best with source regions in the southern Canadian Cordillera, requiring that the basin developed in close proximity to the

  4. The El Abra stadlal in the Eastern Cordillera of Colombia (South America)

    NASA Astrophysics Data System (ADS)

    Kuhry, P.; Hooghiemstra, H.; van Geel, B.; van der Hammen, T.

    The El Abra stadial is a climatic cooling event defined in the Eastern Cordillera of Colombia, which corresponds both in timing and intensity to the Younger Dryas climatic oscillation of the northern North Atlantic region. The stadial was preceded by the relatively warm Guantiva interstadial and followed by the warm Holocene. Colder climatic conditions during the El Abra stadial caused a 400 m lowering of the upper Andean forest limit below its altitudinal location during the preceding Guantiva interstadial. Translated in temperature change, this represents a drop in mean annual temperature of approximately 2 to 3°C. The lowering of the upper forest limit and inferred temperature change for the El Abra stadial, compared to Late Holocene conditions, are in the order of 600 m and 4°C, respectively. The transition of the Guantiva interstadial to the El Abra stadial has been radiocarbon dated at 11,210 ± 90 BP and 10,820 ± 60 BP. Climatic warming may have started shortly after 10,380 ± 90 BP, and near present-day temperatures were reached at least as early as 8920 ± 100 BP. Maximum cooling was probably attained between 10,800 BP and 10,300 BP. Further (AMS) radiocarbon dating is planned to establish more exactly the timing of the El Abra stadial. A glacial advance of El Abra age, the Bocatoma stade, has been recognized in the highest part of the Colombian Eastern Cordillera, the Sierra Nevada del Cocuy. During this advance, glaciers extended some 700 m lower than at present. A climatic cooling event of El Abra age, associated with shifts of the upper Andean forest limit and glacial advances, has also been recognized in other parts of Andean Colombia, including the Central Cordillera and the Sierra Nevada de Santa Marta.

  5. Integrating Multiple Geophysical Methods to Quantify Alpine Groundwater- Surface Water Interactions: Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Glas, R. L.; Lautz, L.; McKenzie, J. M.; Baker, E. A.; Somers, L. D.; Aubry-Wake, C.; Wigmore, O.; Mark, B. G.; Moucha, R.

    2016-12-01

    Groundwater- surface water interactions in alpine catchments are often poorly understood as groundwater and hydrologic data are difficult to acquire in these remote areas. The Cordillera Blanca of Peru is a region where dry-season water supply is increasingly stressed due to the accelerated melting of glaciers throughout the range, affecting millions of people country-wide. The alpine valleys of the Cordillera Blanca have shown potential for significant groundwater storage and discharge to valley streams, which could buffer the dry-season variability of streamflow throughout the watershed as glaciers continue to recede. Known as pampas, the clay-rich, low-relief valley bottoms are interfingered with talus deposits, providing a likely pathway for groundwater recharged at the valley edges to be stored and slowly released to the stream throughout the year by springs. Multiple geophysical methods were used to determine areas of groundwater recharge and discharge as well as aquifer geometry of the pampa system. Seismic refraction tomography, vertical electrical sounding (VES), electrical resistivity tomography (ERT), and horizontal-to-vertical spectral ratio (HVSR) seismic methods were used to determine the physical properties of the unconsolidated valley sediments, the depth to saturation, and the depth to bedrock for a representative section of the Quilcayhuanca Valley in the Cordillera Blanca. Depth to saturation and lithological boundaries were constrained by comparing geophysical results to continuous records of water levels and sediment core logs from a network of seven piezometers installed to depths of up to 6 m. Preliminary results show an average depth to bedrock for the study area of 25 m, which varies spatially along with water table depths across the valley. The conceptual model of groundwater flow and storage derived from these geophysical data will be used to inform future groundwater flow models of the area, allowing for the prediction of groundwater

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    The northern Cordillera, situated in the Canadian northwest, is one of the most actively deforming regions in Canada and host to the highest earthquake activity in the country. Furthermore, it presents a largely contiguous snapshot through almost 4 Gyr of Earth's history across a zone <2000 km in linear extent. Deformation is thought to be driven by tectonic forces transferred from the Alaska-Pacific plate collision eastwards to the Cordilleran Deformation Front (CDF), where the westward edge of the Canadian Shield acts as a rigid backstop. Past studies in the southern Yukon indicate a sharp transition into the craton underlying the CDF and evidence of craton growth through shallow subduction. Further north the proximity of the craton edge to the CDF remains largely unresolved; based on studies of the southern Cordillera and Alaska, significant variations in lithospheric architecture are expected. Additionally, significant seismicity is observed further north off the Beaufort Shelf; however, its relationship to the regional stress fields and associated tectonic forcing is unclear. Despite the high seismicity levels across, detailed study of this region has been limited by insufficient coverage of seismological infrastructure, hindering resolution in past models. With the deployment of the USArray Transportable Array in Alaska over the last several years, combined with regional arrays such as the Yukon-Northwest Seismic Network (YNSN), Banks Island Seismic Network (BISN) and Mackenzie Mountains Experiment, new studies will leverage these datasets enabling more detailed imaging of the structure and seismicity across the region. Here we present a new high-resolution, vertically polarized shear speed and azimuthal model of northwestern Canada and Alaska, constrained by vertical component seismogram fits computed using the Automated Multimode Inversion of Surface, S, and multiple-S waveforms. With this new model, we aim to address key questions relating to the dynamics

  7. Primary medical care in Spain.

    PubMed Central

    Hart, J T

    1990-01-01

    The extremely complex and rapidly but unevenly developing system of primary care in Spain is described. The health centre movement in Spain merits close attention, and could be a useful model for our own service. PMID:2117951

  8. [El Laboratorio Foster de la Residencia de Señoritas. Las relaciones de la JAE con el International Institute for Girls in Spain, y la formación de las jóvenes científicas españolas].

    PubMed

    Portolés, Carmen Magallón

    2007-01-01

    In the first third of the twentieth century, relations among American and Spanish university women began; particularly the relationship between the JAE and the International Institute for Girls in Spain had a positive influence in the education of women scientists in Spain. An interchange of students and teachers came out from this relationship, and Spanish women received scholarships to stay in American universities. The history of the Foster Laboratory and some biographical notes of her founder are included in the paper.

  9. Spain to Join ESO

    NASA Astrophysics Data System (ADS)

    2006-02-01

    Today, during a ceremony in Madrid, an agreement was signed by the Spanish Minister of Education and Science, Mrs. María Jesús San Segundo, and the ESO Director General, Dr. Catherine Cesarsky, affirming their commitment to securing Spanish membership of ESO. ESO PR Photo 05a/06 ESO PR Photo 05a/06 Signature Event in Madrid Following approval by the Spanish Council of Ministers and the ratification by the Spanish Parliament of the ESO Convention and the associated protocols, Spain intends to become ESO's 12th member state on 1 July 2006. "Since long Spain was aware that entering ESO was a logical decision and it was even necessary for a country like Spain because Spain is ranked 8th in astrophysical research", said Mrs. María Jesús San Segundo. "The large scientific installations are not only necessary for research in different fields but are also partners and customers for hi-tech companies, helping to increase the funding of R&D." "Spanish Astronomy has made tremendous strides forward and we are delighted to welcome Spain as a new member of ESO. We very much look forward to working together with our excellent Spanish colleagues," said Dr. Cesarsky. "For ESO, the Spanish accession means that we can draw on the scientific and technological competences, some of them unique in Europe, that have been developed in Spain and, of course, for Europe the Spanish membership of ESO is an important milestone in the construction of the European Research Area." ESO PR Photo 05b/06 ESO PR Photo 05b/06 Signature Event in Madrid Indeed, Spain is an important member of the European astronomical community and has developed impressively over the last three decades, reaching maturity with major contributions in virtually all subjects of astronomy. In addition, Spain hosts, operates or owns a number of competitive facilities dedicated to foster astronomical research, among which the Observatorio del Roque de los Muchachos at La Palma, certainly the premier optical

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    PubMed

    Chua-Barcelo, Racquel Tan

    2014-05-01

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

  12. Multiproxy paleolimnological evidence of Holocene temperature and precipitation variability from the Eastern Cordillera, Colombia

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    The late Holocene was characterized by a number of significant, widespread multi-century climate anomalies, the most prominent and well documented of which are the Little Ice Age and the Medieval Warm Period. Existing paleoclimate reconstructions from South and Central America provide evidence for anomalous climate conditions during these time periods but the spatial and temporal resolution of existing records is limited and quantitative data on the magnitudes of these events is lacking. These limitations make it difficult to fully evaluate the causes and large scale impacts of these apparently global events. Here, we present new high-resolution multiproxy lacustrine records of late Holocene climate change in the Eastern Cordillera of Colombia over the last 2 millennia by combining high-resolution core scanning approaches with molecular and stable isotope analysis of lipid biomarkers. Preliminary paleoclimate reconstructions from these archives suggest that the northern tropics of South America strongly reflect global century-scale climate variability over this time period, with significant hydrologic and temperature anomalies that are broadly synchronous with events in the high latitudes of the northern hemisphere. The magnitude and widespread nature of late Holocene century-scale droughts in this region likely had significant ecological and societal impacts in the Eastern Cordillera.

  13. Polyphase rifting within Rodinia as seen through multiple episodes of mafic volcanism within the Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Cox, G. M.; Halverson, G. P.; Roots, C. F.; MacDonald, F. A.; Plavsa, D.

    2010-12-01

    Neoproterozoic continental flood basalts (CFB) are known from the North American Cordillera and are thought to be associated with the breakup of Rodinia. However, unlike the short eruptive timeframe of Phanerozoic flood basalt provinces, instances of Neoproterozoic CFB within the North American Cordillera are separated by the unusually long time interval of ca 56 My (ca 780 Ma Gunbarrel Event and the ca 717 Ma Franklin Igneous Event), suggestive of poly-phase rifting and a long lived thermal anomaly and/or fertile mantle situated under ancient Laurentia. The Neoproterozoic Tatonduk Inlier, spanning the Alaskan-Yukon border, preserves both mafic volcanics (Pleasant Creek Volcanics) and a large arcuate dyke swarm (Tindir Dyke Swarm). Previous K/Ar dates on the dikes ranging from 532 ± 11 Ma to 644 ± 18 Ma appear to be inconsistent with geological constraints and correlations between the Tatonduk strata and the Neoproterozoic sequence of the well-dated Coal Creek Inlier to the east. We present geochemical data and discuss age and correlative constraints on these mafic rocks and relate these results in terms of the breakup history of Rodinia, timing of mafic magmatism within the possible conjugate margins to Neoproterozoic Laurentia (e.g. Australia and South China) and the role of a mantle plume in the rifting of Rodinia.

  14. Mesozoic transtensional basin history of the Eastern Cordillera, Colombian Andes: Inferences from tectonic models

    NASA Astrophysics Data System (ADS)

    Sarmiento-Rojas, L. F.; Van Wess, J. D.; Cloetingh, S.

    2006-09-01

    Backstripping analysis and forward modeling of 162 stratigraphic columns and wells of the Eastern Cordillera (EC), Llanos, and Magdalena Valley shows the Mesozoic Colombian Basin is marked by five lithosphere stretching pulses. Three stretching events are suggested during the Triassic-Jurassic, but additional biostratigraphical data are needed to identify them precisely. The spatial distribution of lithosphere stretching values suggests that small, narrow (<150 km), asymmetric graben basins were located on opposite sides of the paleo-Magdalena-La Salina fault system, which probably was active as a master transtensional or strike-slip fault system. Paleomagnetic data suggesting a significant (at least 10°) northward translation of terranes west of the Bucaramanga fault during the Early Jurassic, and the similarity between the early Mesozoic stratigraphy and tectonic setting of the Payandé terrane with the Late Permian transtensional rift of the Eastern Cordillera of Peru and Bolivia indicate that the areas were adjacent in early Mesozoic times. New geochronological, petrological, stratigraphic, and structural research is necessary to test this hypothesis, including additional paleomagnetic investigations to determine the paleolatitudinal position of the Central Cordillera and adjacent tectonic terranes during the Triassic-Jurassic. Two stretching events are suggested for the Cretaceous: Berriasian-Hauterivian (144-127 Ma) and Aptian-Albian (121-102 Ma). During the Early Cretaceous, marine facies accumulated on an extensional basin system. Shallow-marine sedimentation ended at the end of the Cretaceous due to the accretion of oceanic terranes of the Western Cordillera. In Berriasian-Hauterivian subsidence curves, isopach maps and paleomagnetic data imply a (>180 km) wide, asymmetrical, transtensional half-rift basin existed, divided by the Santander Floresta horst or high. The location of small mafic intrusions coincides with areas of thin crust (crustal stretching

  15. Precambrian crust and lithosphere beneath the Northern Canadian Cordillera discovered by LITHOPROBE seismic reflection profiling

    NASA Astrophysics Data System (ADS)

    Clowes, R. M.; Cook, F. A.; Snyder, D. B.; van der Velden, A. J.; Hall, K. W.; Erdmer, P.; Evenchick, C. A.

    2003-04-01

    The Cordillera in northern Canada is underlain by westward tapering layers that can be followed from outcrops of Proterozoic strata in the Foreland Belt to the lowermost crust of the orogenic interior, a distance of as much as 500 km across strike. The layering was discovered on two new deep seismic reflection profiles in the Yukon (Line 3; ~650 km) and northern British Columbia (Line 2; ~1245 km in two segments) that were acquired as part of the LITHOPROBE Slave - Northern Cordillera Lithospheric Evolution (SNORCLE) transect. Along Line 3, the layering is visible between 5.0 and 12.0 s (~15 to 36 km depth). It is followed southwestward for nearly 650 km (~500 km across strike) and thins to less than 1.0 s (~3.0-3.5 km thickness) near the Moho at the Yukon-Alaska international boundary. Farther south, along Line 2, the upper part of the layering correlates with outcrops of Proterozoic (1.76-1.0 Ga) strata on the east. Near the outcrop, the layering is >15 km thick. It projects westward into the middle and lower crust for ~700 km (~300 km across strike) where it disappears as a thin taper at the base of the crust. The layering is disrupted at the Tintina fault zone, a late to post-orogenic strike-slip fault with up to 800 km of displacement, which appears as a vertical zone of little reflectivity on both profiles (~300 km apart). The base of the layered reflection zone coincides with the Moho, which exhibits variable character and undulates in a series of broad (~150 km) arches. Although the mantle is generally non-reflective, an event dips eastward from ~14.0 s (~45 km) at the western end of Line 3 near the coast to ~21.0 s (73 km depth) beneath exposed Eocene magmatic rocks. It is interpreted as a relict subduction surface of the Kula plate. Some implications of the interpretation of Proterozoic layered rocks beneath most of the northern Cordillera are: (1) ancient North American crust and lithosphere project westward beneath most of the Northern Cordillera, (2

  16. Test Reviewing in Spain

    ERIC Educational Resources Information Center

    Muniz, Jose; Fernandez-Hermida, Jose R.; Fonseca-Pedrero, Eduardo; Campillo-Alvarez, Angela; Pena-Suarez, Elsa

    2012-01-01

    The proper use of psychological tests requires that the measurement instruments have adequate psychometric properties, such as reliability and validity, and that the professionals who use the instruments have the necessary expertise. In this article, we present the first review of tests published in Spain, carried out with an assessment model…

  17. Supported Employment in Spain.

    ERIC Educational Resources Information Center

    Verdugo, Miguel Angel; Borja, F.; de Urries, Jordan; Bellver, Fernando; Martinez, Salvador

    1998-01-01

    Supported employment is growing in Spain, assisted by models from other countries and national legislation. The Spanish Association of Supported Employment is providing a framework for program development. The field must deal with the lack of systematic evaluation and with funding problems. (SK)

  18. Vocational Training in Spain.

    ERIC Educational Resources Information Center

    Genovard, Candido; And Others

    Vocational training in Spain suffers from a fundamental initial disadvantage, namely the subsidiary position that it occupies in the general structure of the country's educational system. The situation has been aggravated by the sector's relative neglect by the government, which has been forced to concentrate its efforts on secondary and…

  19. Embassy of Spain visit

    NASA Image and Video Library

    2016-09-29

    Delegates from the Embassy of Spain visited Goddard on Sept 29, 2016. Center Director Chris Scolese gave a brief overview of the Center and the guests then toured B29 James Webb Space Telescope (JWST) in clean room, and B28 Hyperwall.

  20. Career Development in Spain.

    ERIC Educational Resources Information Center

    Talavera, Elvira Repetto; Moreno, Luisa Rodriguez; Romeo, Javier; Malik, Beatriz

    In Spain, the term "career development" refers to vocational or career guidance services. The 1983 Law on University Reform conferred on universities the freedom of teaching, endowing them with legal status and administrative powers. Thus, there are no regulations regarding guidance at this educational level. Guidance departments in…

  1. [Foreign immigration in Spain].

    PubMed

    Serra Yoldi, I

    1997-01-01

    This article, translated from the original Spanish, analyzes recent trends in immigration to Spain. Information is provided on annual totals of immigrants and emigrants, 1976-1991; resident foreigners by nationality, 1990-1994; resident foreigners by province and continent of origin, 1991; occupations of immigrants, 1990-1991; migrant characteristics; attitudes toward immigration; and assimilation of immigrants.

  2. Test Reviewing in Spain

    ERIC Educational Resources Information Center

    Muniz, Jose; Fernandez-Hermida, Jose R.; Fonseca-Pedrero, Eduardo; Campillo-Alvarez, Angela; Pena-Suarez, Elsa

    2012-01-01

    The proper use of psychological tests requires that the measurement instruments have adequate psychometric properties, such as reliability and validity, and that the professionals who use the instruments have the necessary expertise. In this article, we present the first review of tests published in Spain, carried out with an assessment model…

  3. [Fertility decline in Spain].

    PubMed

    Arango, J

    1987-01-01

    The historical processes of secular fertility decline in Spain and Portugal are not well understood. Very few microdemographic studies of small geographic regions or particular social strata have been done. A contribution by David Reher to the First Spanish-Portuguese-Italian Historical Demography Conference on the fertility decline in the interior province of Cuenca, Spain, uses the own-children method to analyze changes in marital fertility in the 19th and 20th centuries. Reher discovered a slight fertility decline of perhaps 15% which occurred between the end of the 18th century and 1860-75. The fertility decline did not resume until after the Spanish Civil War, and then it was a very gradual and continuous process. When instead of the total female population, women aged 35-39 were studied, unequivocal signs of fertility control appeared. Conscious fertility control thus appears to have begun among older women limiting rather than spacing births. Reher's analysis by social groups demonstrates that fertility declined first and more rapidly in the nonagricultural and urban populations and among the higher income groups. The fertility decline in Cuenca was certainly not identical to that in most of Spain, but may have been fairly typical of a large part of the interior. Another contribution to the Historical Demography Conference, by Anna Cabre and Isabel Pujadas, analyzes fertility trends and cyclical fluctuations in 20th century Cataluna, arguing that they must be placed in historical perspective if recent changes are to be understood and plausible projections made. Their work demonstrates the value of selecting a relatively homogeneous geographic unit for analysis. The contribution of Margarita Delgado to the conference analyzed interregional fertility differences in contemporary Spain. The high legitimate fertility of the south of Spain is accentuated by high nuptiality rates. In central Spain, the combination of high legitimate fertility rates and low

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

    NASA Astrophysics Data System (ADS)

    Struth, Lucía; Babault, Julien; Teixell, Antonio

    2015-12-01

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

  5. DNA Barcoding Survey of Anurans across the Eastern Cordillera of Colombia and the Impact of the Andes on Cryptic Diversity

    PubMed Central

    Guarnizo, Carlos E.; Paz, Andrea; Muñoz-Ortiz, Astrid; Flechas, Sandra V.; Méndez-Narváez, Javier; Crawford, Andrew J.

    2015-01-01

    Colombia hosts the second highest amphibian species diversity on Earth, yet its fauna remains poorly studied, especially using molecular genetic techniques. We present the results of the first wide-scale DNA barcoding survey of anurans of Colombia, focusing on a transect across the Eastern Cordillera. We surveyed 10 sites between the Magdalena Valley to the west and the eastern foothills of the Eastern Cordillera, sequencing portions of the mitochondrial 16S ribosomal RNA and cytochrome oxidase subunit 1 (CO1) genes for 235 individuals from 52 nominal species. We applied two barcode algorithms, Automatic Barcode Gap Discovery and Refined Single Linkage Analysis, to estimate the number of clusters or “unconfirmed candidate species” supported by DNA barcode data. Our survey included ~7% of the anuran species known from Colombia. While barcoding algorithms differed slightly in the number of clusters identified, between three and ten nominal species may be obscuring candidate species (in some cases, more than one cryptic species per nominal species). Our data suggest that the high elevations of the Eastern Cordillera and the low elevations of the Chicamocha canyon acted as geographic barriers in at least seven nominal species, promoting strong genetic divergences between populations associated with the Eastern Cordillera. PMID:26000447

  6. Searching for the Neogene orogenic mechanism that uplifted the Eastern Cordillera of Colombia: Constraints from seismology, geochronolgy and geochemistry

    NASA Astrophysics Data System (ADS)

    Monsalve, G.; Posada, G. A.; Cardona, A.; Poveda, E.; Valencia, V.; Blanco Chia, J. F.

    2016-12-01

    The Eastern Cordillera of Colombia is one of the three ranges that form the Colombian Andes. At latitudes between 4° and 6° North, the top of the cordillera is a plateau surface, with a mean elevation of 2600 m above sea level and a width of nearly 130 km. The surface geology mainly consists of sedimentary rocks deposited within an extensional basin during the Jurassic and Cretaceous periods, followed by Cenozoic accumulation in a more continental environment; inversion tectonics allowed its uplift during the Cenozoic. We use seismological, geochronological and geochemical techniques to constrain the lithospheric structure beneath the Eastern Cordillera plateau and to better elucidate the mechanisms that played a relevant role in its uplift during the Neogene. Ps teleseismic receiver functions indicate that crustal thickness in the area is between 50 and 60 km; sequential H-K stacking, taking into account the low velocity sedimentary cover, shows that this crustal thickness estimation is robust. Sp receiver functions are also consistent with the previously estimated Moho depths and suggest a lithospheric thickness of around 100 km. In the region of the plateau, there are a few volcanic domes, whose associated high potassium volcanic rocks yielded a 238U-206Pb zircon age of 6 m.a. Previous estimates of Cenozoic shortening in the Eastern Cordillera are insufficient to explain the high elevations of the plateau, so we propose the existence of an additional mechanism such as partial lithospheric delamination.

  7. DNA Barcoding Survey of Anurans across the Eastern Cordillera of Colombia and the Impact of the Andes on Cryptic Diversity.

    PubMed

    Guarnizo, Carlos E; Paz, Andrea; Muñoz-Ortiz, Astrid; Flechas, Sandra V; Méndez-Narváez, Javier; Crawford, Andrew J

    2015-01-01

    Colombia hosts the second highest amphibian species diversity on Earth, yet its fauna remains poorly studied, especially using molecular genetic techniques. We present the results of the first wide-scale DNA barcoding survey of anurans of Colombia, focusing on a transect across the Eastern Cordillera. We surveyed 10 sites between the Magdalena Valley to the west and the eastern foothills of the Eastern Cordillera, sequencing portions of the mitochondrial 16S ribosomal RNA and cytochrome oxidase subunit 1 (CO1) genes for 235 individuals from 52 nominal species. We applied two barcode algorithms, Automatic Barcode Gap Discovery and Refined Single Linkage Analysis, to estimate the number of clusters or "unconfirmed candidate species" supported by DNA barcode data. Our survey included ~7% of the anuran species known from Colombia. While barcoding algorithms differed slightly in the number of clusters identified, between three and ten nominal species may be obscuring candidate species (in some cases, more than one cryptic species per nominal species). Our data suggest that the high elevations of the Eastern Cordillera and the low elevations of the Chicamocha canyon acted as geographic barriers in at least seven nominal species, promoting strong genetic divergences between populations associated with the Eastern Cordillera.

  8. Glacier changes and climate trends derived from multiple sources in the data scarce Cordillera Vilcanota region, southern Peruvian Andes

    NASA Astrophysics Data System (ADS)

    Salzmann, N.; Huggel, C.; Rohrer, M.; Silverio, W.; Mark, B. G.; Burns, P.; Portocarrero, C.

    2013-01-01

    The role of glaciers as temporal water reservoirs is particularly pronounced in the (outer) tropics because of the very distinct wet/dry seasons. Rapid glacier retreat caused by climatic changes is thus a major concern, and decision makers demand urgently for regional/local glacier evolution trends, ice mass estimates and runoff assessments. However, in remote mountain areas, spatial and temporal data coverage is typically very scarce and this is further complicated by a high spatial and temporal variability in regions with complex topography. Here, we present an approach on how to deal with these constraints. For the Cordillera Vilcanota (southern Peruvian Andes), which is the second largest glacierized cordillera in Peru (after the Cordillera Blanca) and also comprises the Quelccaya Ice Cap, we assimilate a comprehensive multi-decadal collection of available glacier and climate data from multiple sources (satellite images, meteorological station data and climate reanalysis), and analyze them for respective changes in glacier area and volume and related trends in air temperature, precipitation and in a more general manner for specific humidity. While we found only marginal glacier changes between 1962 and 1985, there has been a massive ice loss since 1985 (about 30% of area and about 45% of volume). These high numbers corroborate studies from other glacierized cordilleras in Peru. The climate data show overall a moderate increase in air temperature, mostly weak and not significant trends for precipitation sums and probably cannot in full explain the observed substantial ice loss. Therefore, the likely increase of specific humidity in the upper troposphere, where the glaciers are located, is further discussed and we conclude that it played a major role in the observed massive ice loss of the Cordillera Vilcanota over the past decades.

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

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

  10. Air temperature, radiation budget and area changes of Quisoquipina glacier in the Cordillera Vilcanota (Peru)

    NASA Astrophysics Data System (ADS)

    Suarez, Wilson; Macedo, Nicolás; Montoya, Nilton; Arias, Sandro; Schauwecker, Simone; Huggel, Christian; Rohrer, Mario; Condom, Thomas

    2015-04-01

    The Peruvian Andes host about 71% of all tropical glaciers. Although several studies have focused on glaciers of the largest glaciered mountain range (Cordillera Blanca), other regions have received little attention to date. In 2011, a new program has been initiated with the aim of monitoring glaciers in the centre and south of Peru. The monitoring program is managed by the Servicio Nacional de Meteorología e Hidrología del Perú (SENAMHI) and it is a joint project together with the Universidad San Antonio Abad de Cusco (UNSAAC) and the Autoridad Nacional del Agua (ANA). In Southern Peru, the Quisoquipina glacier has been selected due to its representativeness for glaciers in the Cordillera Vilcanota considering area, length and orientation. The Cordillera Vilcanota is the second largest mountain range in Peru with a glaciated area of approximately 279 km2 in 2009. Melt water from glaciers in this region is partly used for hydropower in the dry season and for animal breeding during the entire year. Using Landsat 5 images, we could estimate that the area of Quisoquipina glacier has decreased by approximately 11% from 3.66 km2 in 1990 to 3.26 km2 in 2010. This strong decrease is comparable to observations of other tropical glaciers. In 2011, a meteorological station has been installed on the glacier at 5180 m asl., measuring air temperature, wind speed, relative humidity, net short and longwave radiation and atmospheric pressure. Here, we present a first analysis of air temperature and the radiation budget at the Quisoquipina glacier for the first three years of measurements. Additionally, we compare the results from Quisoquipina glacier to results obtained by the Institut de recherche pour le développement (IRD) for Zongo glacier (Bolivia) and Antizana glacier (Ecuador). For both, Quisoquipina and Zongo glacier, net shortwave radiation may be the most important energy source, thus indicating the important role of albedo in the energy balance of the glacier

  11. Structural and thermochronological evidence for Paleogene basement-involved shortening in the axial Eastern Cordillera, Colombia

    NASA Astrophysics Data System (ADS)

    Saylor, Joel E.; Horton, Brian K.; Stockli, Daniel F.; Mora, Andrés; Corredor, Jaime

    2012-11-01

    Although most recent studies regard the northern Andes primarily as a low-shortening inversion orogen, new mapping and thermochronology along the paired basement-involved Floresta massif and Floresta basin in the axial Eastern Cordillera of Colombia suggest major Paleogene shortening in a ramp-flat fold-thrust belt. Field mapping indicates that the hanging wall of the east-directed Soápaga fault system contains a series of upright thrust sheets with flat-on-flat cutoff relationships and a deformed footwall characterized by a complex triangle zone. These geometries necessitate roughly east-west shortening exceeding that of a previously mapped overturned hanging wall anticline and disharmonic footwall folds. Zircon (U-Th)/He (ZHe) ages indicate exhumation-induced cooling of the Soápaga hanging wall through the ˜180 °C closure temperature at 31-25 Ma. This cooling postdated documented shortening to the west and predated shortening to the east, suggesting an eastward progression of Paleogene deformation. Synorogenic Oligocene footwall strata of the Floresta basin contain distal fine-grained sediments and lack growth strata or Oligocene detrital ZHe ages, suggesting relatively high heave along the Soápaga fault system. These results are consistent with a rapidly eastward-propagating, basement-involved fold-thrust belt with ramp-flat structures that accommodated tens of km of shortening. Long-term stasis of the deformation front on the eastern and western flanks of the Eastern Cordillera due to localization of Neogene shortening along Mesozoic rift-bounding normal faults indicates a shift in deformational style in late Oligocene-early Miocene time. This geometric and temporal framework implies: 1) a total shortening in the northern Andes exceeding most current estimates; 2) Paleogene deformation in the Eastern Cordillera marked by rapid advances of the deformation front along a ramp-flat thrust system; and 3) focused Neogene reactivation (inversion) of master rift

  12. Spain: NATO or Neutrality,

    DTIC Science & Technology

    1980-04-01

    is tied up first and foremost with Western Europe, its geographi- cal, historical, cultural , and social context. It is natural, then, that the defence...forcibly but it is more forcibly stated by the facts of economic and cultural links. The Spanish democracy, new but impressive, finds its obvious political...political, economic, cultural and social ones. A last point might be made on this matter. It is surely in the Interests of the Alliance that Spain, whether in

  13. Pyrenees Mtns., Spain

    NASA Image and Video Library

    2001-10-22

    This ASTER image, acquired on August 1, 2000, covers an area of 57 by 29 km and covers part of the central Pyrenees in Spain. The Pyrenees in southwestern Europe extend for about 435 kilometers (about 270 miles) from the Bay of Biscay to the Mediterranean Sea, separating the Iberian Peninsula from the rest of Europe. The Pyrenees form most of the boundary between France and Spain, and encompass the tiny principality of Andorra. Approximately two-thirds of the mountains lie in Spain. The central Pyrenees extend to the Collines du Perche and contain the highest peaks of the system, including Pico de Aneto, the highest at 3,404 meters (11,168 feet). ASTER bands 4, 3 and 2 were displayed in red, green and blue. In this combination, snow is blue, vegetation is green, bare rocks are pink and dark blue, and clouds are white. The image is located at 42.6 degrees north latitude and 0.6 degrees east longitude. http://photojournal.jpl.nasa.gov/catalog/PIA11162

  14. Occupational cancer in Spain.

    PubMed Central

    González, C A; Agudo, A

    1999-01-01

    The knowledge of specific problems of occupational cancer in Spain is scarce. The environment of the workplace has improved over the last few years after a long period distinguished by bad working conditions, incomplete legislation, and insufficient safety measures and control. It has been estimated that 3,083,479 workers (25.4% of employees) were exposed to carcinogens. The most common occupational exposures to carcinogenic agents were solar radiation, environmental tobacco smoke, silica, and wood dust. The highest number of employees were exposed to silica crystalline (404,729), diesel engine exhaust (274,321), rubber products (99,804), benzene (89,932), ethylene dibromide (81,336), agents used in furniture and cabinet making (72,068), and formaldehyde (71,189). The percentage of total cancer deaths attributed to occupational exposure was 4% (6% in men, 0.9% in women). Compared with other European countries, the incidence of lung cancer and leukemia in Spain are one of the lowest, but it is rapidly increasing. The incidence of urinary bladder and larynx cancer, on the contrary, are one of the highest. Few studies on occupational cancer have been conducted in Spain. The main problems are the availability of death certificates and the quality of the information on occupation in mortality of statistics. It is necessary to improve methods of assessment of exposures using expert hygienists and biologic markers of exposure and diseases. Reduction of cancer by limiting or avoiding exposure to known occupational carcinogens is still necessary. PMID:10350510

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

    NASA Astrophysics Data System (ADS)

    Reynhout, S.

    2015-12-01

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

  16. Stable isotopic constraints on the nature of the syntectonic fluid regime of the Canadian cordillera

    SciTech Connect

    Nesbitt, B.E.; Muehlenbacks, K. )

    1991-05-01

    Oxygen, hydrogen and carbon isotopic analyses of rocks from the Canadian Cordillera document regional variations in the origins and evolution of crustal fluids. High temperature systems in unmetamorphosed, felsic volcanic rocks are characterized by low {delta}{sup 18}O values. Veins in regional metamorphic rocks are characterized by {delta}{sup 18}O values that reflect approximate oxygen isotopic equilibration of the fluids with regional rock units. The {delta} D studies indicate that both systems were dominated by meteoric water. The {delta}{sup 13}C values for vein carbonate indicate a regional lithologic control on {delta}{sup 13}C values. The data indicate that convection of surface fluids to depth of 10 or more kilometers during orogenesis was common. The existence of deep convection cells involving meteoric water further indicates that fluid pressures to these depths must have been approximately hydrostatic. Regional structural style appears to exert an important control on the depth of penetration of surface fluids.

  17. The Unusual Nature of Recent Snowpack Declines in the North American Cordillera

    NASA Astrophysics Data System (ADS)

    Pederson, Gregory T.; Gray, Stephen T.; Woodhouse, Connie A.; Betancourt, Julio L.; Fagre, Daniel B.; Littell, Jeremy S.; Watson, Emma; Luckman, Brian H.; Graumlich, Lisa J.

    2011-07-01

    In western North America, snowpack has declined in recent decades, and further losses are projected through the 21st century. Here, we evaluate the uniqueness of recent declines using snowpack reconstructions from 66 tree-ring chronologies in key runoff-generating areas of the Colorado, Columbia, and Missouri River drainages. Over the past millennium, late 20th century snowpack reductions are almost unprecedented in magnitude across the northern Rocky Mountains and in their north-south synchrony across the cordillera. Both the snowpack declines and their synchrony result from unparalleled springtime warming that is due to positive reinforcement of the anthropogenic warming by decadal variability. The increasing role of warming on large-scale snowpack variability and trends foreshadows fundamental impacts on streamflow and water supplies across the western United States.

  18. The unusual nature of recent snowpack declines in the North American cordillera.

    PubMed

    Pederson, Gregory T; Gray, Stephen T; Woodhouse, Connie A; Betancourt, Julio L; Fagre, Daniel B; Littell, Jeremy S; Watson, Emma; Luckman, Brian H; Graumlich, Lisa J

    2011-07-15

    In western North America, snowpack has declined in recent decades, and further losses are projected through the 21st century. Here, we evaluate the uniqueness of recent declines using snowpack reconstructions from 66 tree-ring chronologies in key runoff-generating areas of the Colorado, Columbia, and Missouri River drainages. Over the past millennium, late 20th century snowpack reductions are almost unprecedented in magnitude across the northern Rocky Mountains and in their north-south synchrony across the cordillera. Both the snowpack declines and their synchrony result from unparalleled springtime warming that is due to positive reinforcement of the anthropogenic warming by decadal variability. The increasing role of warming on large-scale snowpack variability and trends foreshadows fundamental impacts on streamflow and water supplies across the western United States.

  19. Geochronology and Equilibrium Line Altitudes of LLGM through Holocene Glaciations from the Tropical Cordillera Huayhuash, Peru

    NASA Astrophysics Data System (ADS)

    Hall, S. R.; Ramage, J. M.; Rodbell, D. T.; Finkel, R. C.; Smith, J. A.; Mark, B. G.; Farber, D. L.

    2006-12-01

    Geomorphologic relationships and cosmogenic 10Be ages from the Central Peruvian Andes reveal a rich record of glaciations from at least the late Holocene, Late Glacial, Last Local Glacial Maximum (LLGM), and older more extensive glaciations - dated between 50ka and 440ka in both the Cordillera Blanca, to the north and the Junin Region to the south. The Cordillera Huayhuash (10.3°S, 76.9°W) is located between these two well-studied regions. The spine of the range trends nearly north-south and contains a substantial east-west spur which together can be used to evaluate the spatial variation in paleo-ELAs. The range is thus a key location to study changes in ice extent and equilibrium line altitudes (ELAs) between the LLGM and modern periods. Modern glaciers are confined to altitudes >4800 m and the present (1997) ELA is 4800- 5100m. In order to determine the paleo-ice positions of glaciers in different valleys we have developed a new chronology from cosmogenic 10Be ages of moraine boulder and 14C basal bog core ages. Through field mapping of glacial features, analysis of satellite imagery, digital elevation models (DEMs), and geochronology, we have delineated the ice limits associated with the LLGM, Late Glacial, and Late Holocene advances. Ages in the three valleys we have studied cluster at ~29ka, ~13ka, and ~9ka and overall we have identified surfaces with ages that range from 39.9±1.4ka to 0.2ka±0.05ka. Based on these data, we have mapped the extent of the correlative paleo-glaciers in these three drainages and extracted the modern hypsometry for each paleo-glacier from the DEMs. From this data set, we have generated paleo- ELAs using a range of methods: Toe-to-Headwall-Altitude Ratio (THAR), the Accumulation Area Ratio (AAR), and Accumulation Area Balance Ratio (AABR). For each of the LLGM, Late Glacial and Holocene stages, we have calculated both: (1) the temperature depression assuming no moisture variations, and (2) the potential relative moisture

  20. A new species of Choerophryne (Anura, Microhylidae) from the central cordillera of Papua New Guinea.

    PubMed

    Iannella, Amy; Richards, Stephen; Oliver, Paul

    2014-01-09

    We describe a new species of very small microhylid frog in the genus Choerophryne from the upper Strickland River area, Western and Southern Highlands Provinces, Papua New Guinea. Choerophryne gracilirostris sp. nov. can be distinguished from congeners by the following combination of characters: small size (SUL 13.5-14.7 mm), moderately long and narrow snout, first finger without expanded disk and advertisement call consisting of 3-5 distinctly pulsed notes repeated in long sequences. Males in the type series were calling from within leaf litter in primary hill rainforest (213-1368 m a.s.l.). The new species is the third Choerophryne known from the southern side of New Guinea's central cordillera. Measurements of a juvenile specimen (rare because most Choerophryne collected are calling males) demonstrate that the distinctive rostral projection of this genus exhibits pronounced positive allometry.

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

    NASA Astrophysics Data System (ADS)

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

    2004-04-01

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

  2. Miocene non-marine diatoms from the western Cordillera basins of northern Peru

    USGS Publications Warehouse

    Fourtanier, E.; Gasse, F.; Bellier, O.; Bonhomme, M.G.; Robles, I.

    1993-01-01

    Diatom assemblages are documented from diatomite layers of two Miocene fluvio-lacustrine units from the basins of the western Cordillera of northern Peru: the Namora Formation and the Cajabamba Formation. Emphasis is given to taxa of particular stratigraphic interest. The diatom assemblages indicate for the Namora Formation the occurrence of swampy conditions with very dilute, low alkalinity water. The diatom assemblages of the Cajabamba Formation reflect the occurrence of fresh, slightly alkaline, eutrophic lakes with deep water in some samples, and swampy conditions with relatively high salt content in other samples. The Namora formation is late Miocene in age based on the diatom assemblages and radiometric analyses. The diatom layers of the Cajabamba Formation are dated as late middle to early late Miocene. -from Authors

  3. Crustal shortening and Eocene extension in the southeastern Canadian Cordillera: Some thermal and rheological considerations

    NASA Astrophysics Data System (ADS)

    Liu, Mian; Furlong, Kevin P.

    1993-06-01

    Metamorphic core complexes in the southeastern Canadian Cordillera were formed during Eocene crustal extension, shortly (within a few millions of years) after Late Jurassic-Paleocene crustal shortening. Thermal-rheological modeling, constrained by geological and geochronological studies of the Valhalla core complex and other core complexes in this region, is used to investigate two major problems concerning the formation of these core complexes: (1) the dynamic links between crustal shortening and extension and (2) the cooling history and unroofing rates during extension. Thermal-rheological effects associated with crustal shortening are integrated through the history of crustal compression, since crustal shortening in this region was a long and slow process and cannot be treated as an instantaneous event. Our results suggest that crustal shortening may have played an important role in Eocene extension in the southeastern Canadian Cordillera by (1) producing a thickened and therefore unstable crust and (2) thermally weakening the lithosphere. However, heat generated by crustal shortening is not enough to account for the thermal state of the Valhalla complex, and additional heat sources at depth may be necessary. We then investigate thermal evolution during extension in both a simple shear model and a progressive pure stretching model. We show that the geotherm in an extensional region is time-and space-dependent and is affected by many variables including the preextensional thermal history and the mode of extension. Thus caution needs to be exercised when inferring unroofing rates from thermochronologic data. The cooling history of the Valhalla core complex may be explained by unroofing at rates of 1-2 mm/yr.

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

    PubMed Central

    Chua-Barcelo, Racquel Tan

    2014-01-01

    Objective To conduct a survey on the common name/s, traditional uses and cultural importance of the edible wild fruits in different municipalities of Benguet, Cordillera administrative region. Methods Interviews using questionnaires with barangay leaders and indigenous people were conducted with 176 key informants from June 2011 to July 2013. Results A total of 36 fruit species were found in different municipalities of Benguet. These fruit species belong to 27 genera and 20 families. Among the 13 municipalities of Benguet, Kibungan has the highest number of species. There are many uses of wild fruits which ranged from food (snack/dessert/table food), forage (especially for birds, monkeys and wild animals such as cloud rat and grass eaters), offertory, processed/preserved (as jam, jellies, candies, juice and wine), condiment or ingredient (for cooking), source of dye or ink, decoration (to garnish food) and as medicine to common ailments or health problems. Based on the inventory and calculated cultural importance index, Garcinia binucao (balokok) belonging to Clusiaceae is the most abundant fruit, hence it is the commonly used fruit for various purposes such as food, forage, processing/preservation and condiment/ingredient; Vaccinium myrtoides (ayusip) for offerings and as source of dye/ink; Saurauia elegans (uyok) for decoration, and, Antidesma bunius (bugnay) for medicine. Conclusions Benguet province in the Cordillera region provides a diversity of edible wild fruits. The data gathered from the study signifies that collection, processing and utilization of edible wild fruits are still part of the daily activities of the people in Benguet. PMID:25183144

  5. Measurements of light absorbing particulates on the glaciers in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Schmitt, C. G.; All, J. D.; Schwarz, J. P.; Arnott, W. P.; Cole, R. J.; Lapham, E.; Celestian, A.

    2014-10-01

    Glaciers in the tropical Andes have been rapidly losing mass since the 1970s. In addition to the documented increase in air temperature, increases in light absorbing particulates deposited on glaciers could be contributing to the observed glacier loss. Here we report on measurements of light absorbing particulates sampled from glaciers during three surveys in the Cordillera Blanca in Peru. During three research expeditions in the dry seasons (May-August) of 2011, 2012 and 2013, two hundred and forty snow samples were collected from fifteen mountain peaks over altitudes ranging from 4800 to nearly 6800 m. Several mountains were sampled each of the three expeditions and some mountains were sampled multiple times during the same expedition. Collected snow samples were melted and filtered in the field then later analyzed using the Light Absorption Heating Method (LAHM), a new technique that measures the ability of particulates on filters to absorb visible light. LAHM results have been calibrated using filters with known amounts of fullerene soot, a common industrial surrogate for black carbon (BC). As sample filters often contain dust in addition to BC, results are presented in terms of effective Black Carbon (eBC). During the 2013 survey, snow samples were collected and kept frozen for analysis with a Single Particle Soot Photometer (SP2). Calculated eBC mass from the filter analysis and the SP2 refractory Black Carbon (rBC) results were well correlated (r2 = 0.92). These results indicate that a substantial portion of the light absorbing particulates in the more polluted areas were likely BC. The three years of data show that glaciers in the Cordillera Blanca Mountains close to human population centers have substantially higher levels of eBC (as high as 70 ng g-1) than remote glaciers (as low as 2.0 ng g-1 eBC), indicating that population centers can influence local glaciers by sourcing BC.

  6. Measurements of light-absorbing particles on the glaciers in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Schmitt, C. G.; All, J. D.; Schwarz, J. P.; Arnott, W. P.; Cole, R. J.; Lapham, E.; Celestian, A.

    2015-02-01

    Glaciers in the tropical Andes have been rapidly losing mass since the 1970s. In addition to the documented increase in temperature, increases in light-absorbing particles deposited on glaciers could be contributing to the observed glacier loss. Here we report on measurements of light-absorbing particles sampled from glaciers during three surveys in the Cordillera Blanca Mountains in Peru. During three research expeditions in the dry seasons (May-August) of 2011, 2012 and 2013, 240 snow samples were collected from 15 mountain peaks over altitudes ranging from 4800 to nearly 6800 m. Several mountains were sampled each of the 3 years and some mountains were sampled multiple times during the same year. Collected snow samples were melted and filtered in the field then later analyzed using the Light Absorption Heating Method (LAHM), a new technique that measures the ability of particles on filters to absorb visible light. LAHM results have been calibrated using filters with known amounts of fullerene soot, a common industrial surrogate for black carbon (BC). As sample filters often contain dust in addition to BC, results are presented in terms of effective black carbon (eBC). During the 2013 survey, snow samples were collected and kept frozen for analysis with a Single Particle Soot Photometer (SP2). Calculated eBC mass from the LAHM analysis and the SP2 refractory black carbon (rBC) results were well correlated (r2 = 0.92). These results indicate that a substantial portion of the light-absorbing particles in the more polluted regions were likely BC. The 3 years of data show that glaciers in the Cordillera Blanca Mountains close to human population centers have substantially higher levels of eBC (as high as 70 ng g-1) than remote glaciers (as low as 2.0 ng g-1 eBC), indicating that population centers can influence local glaciers by sourcing BC.

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

    NASA Astrophysics Data System (ADS)

    Kammer, Andreas; Montana, Jorge; Piraquive, Alejandro

    2016-04-01

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

  8. K-Ar geochronology of the late cenozoic volcanic rocks of the Cordillera Occidental, southernmost Peru

    NASA Astrophysics Data System (ADS)

    Tosdal, Richard M.; Farrar, Edward; Clark, Alan H.

    1981-05-01

    Twenty-four K-Ar radiometric ages are presented for late Cenozoic continental volcanic rocks of the Cordillera Occidental of southernmost Perú (lat. 16° 57'-17° 36'S). Rhyodacitic ignimbrite eruptions began in this transect during the Late Oligocene and continued episodically through the Miocene. The development of andesitic-dacitic strato volcanoes was initiated in the Pliocene and continues to the present. The earliest ignimbrite flows (25.3-22.7 Ma) are intercalated in the upper, coarsely-elastic member of the Moquegua Formation and demonstrate that this sedimentary unit accumulated in a trough, parallel to Andean tectonic trends, largely in the Oligocene. More voluminous ash-flow eruptions prevailed in the Early Miocene (22.8-17.6 Ma) and formed the extensively preserved Huaylillas Formation. This episode was coeval with a major phase of Andean uplift, and the pyroclastics overlie an erosional surface of regional extent incised into a Paleogene volcano-plutonic arc terrain. An age span of 14.2-8.9 Ma (mid-Late Miocene) is indicated for the younger Chuntacala Formation, which again comprises felsic ignimbrite flows, largely restricted to valleys incised into the pre-Huaylillas Formation lithologies, and, at lower altitudes, an extensive aggradational elastic facies. The youngest areally extensive ignimbrites, constituting the Sencca Formation, were extruded during the Late Miocene. In the earliest Pliocene, the ignimbrites were succeeded by more voluminous calcalkaline, intermediate flows which generated numerous large and small stratovolcanoes; these range in age from 5.3 to 1.6 Ma. Present-day, or Holocene, volcanism is restricted to several large stratovolcanoes which had begun their development during the Pleistocene (by 0.7 Ma). The late Oligocene/Early Miocene (ca. 22-23 Ma) reactivation of the volcanic arc coincided with a comparable increase in magmatic activity throughout much of the Cordilleras Occidental and Oriental of the Central Andes.

  9. Mass loss and imbalance of glaciers along the Andes Cordillera to the sub-Antarctic islands

    NASA Astrophysics Data System (ADS)

    Mernild, Sebastian H.; Beckerman, Andrew P.; Yde, Jacob C.; Hanna, Edward; Malmros, Jeppe K.; Wilson, Ryan; Zemp, Micheal

    2015-10-01

    Here, we examine available glacier mass-balance records between 1993 and 2012 for Andes Cordillera, South America (6.5°N-45.8°S), and the sub-Antarctic islands around the northern tip of the Antarctic Peninsula (62.7°S-63.8°S) to determine their recent mass loss and imbalance with the present climate. The mean annual observed mass-balance Ba changed from - 620 ± 390 (1993-2002) to - 740 ± 240 kg m- 2 yr- 1 (2003-2012) and for this past decade showed a decrease in Ba from south to north. These glaciers had a mean accumulation area ratio of 0.42, which is below the AAR value for glaciers in equilibrium, reflecting mean area and volume imbalances of 23% and 27%, respectively. Glaciers in the northern part of Andes Cordillera are most out of balance with the present climate (33%), while glaciers on the sub-Antarctic islands are only slightly out of balance (4%). We identified a spatiotemporal cycle of Ba that distinguishes glaciers on the sub-Antarctic islands from glaciers in the Andes using an Empirical Orthogonal Function analysis. This analysis also revealed that South America should be divided into three individual glacier regions, and not two regions as earlier stated. Overall, the spatiotemporal cycles identified correlate to the multivariate El Niño Southern Oscillation Index instantaneously (zero-year lag-time) and to the Pacific Decadal Oscillation with an approximately eight-year lag-time.

  10. Guerrero terrane of Mexico: Its role in the Southern, Cordillera from new geochemical data

    NASA Astrophysics Data System (ADS)

    Centeno-García, Elena; Ruíz, Joaquín; Coney, Peter J.; Patchett, P. Jonathan; Ortega-Gutiérrez, Fernando

    1993-05-01

    The Guerrero terrane makes up most of the western part of Mexico, is one of the largest terranes of the North American Cordillera, and is characterized by an Upper Jurassic-Lower Cretaceous volcanic-sedimentary sequence of are affinity. Metamorphic rocks that crop out in the western area of the terrane (Arteaga complex) may represent its basement. They are mostly composed of terrigenous sediments (Varales Formation) with minor basaltic pillow lavas, chert, tuff, and limestone. Initial ɛNd values (+13) and rare earth element (REE) values for pillow lavas of the Arteaga complex are characteristic of mid-ocean ridge basalts (MORB). In contrast, the Varales Formation sedimentary rocks from the Arteaga complex have negative initial ɛNd (-6.2 and -7.2) and are enriched in light REEs. These data indicate that the sediments of the Varales Formation were supplied from an evolved continental crust. The overlying Jurassic(?)-Cretaceous arc-related rocks have initial ɛNd (+7.9 to +3.9) and REE patterns similar to those of evolved intraoceanic island arcs. These data show that the evolution of the Guerrero terrane had an early pre-Cretaceous(?) stage, which consisted of an oceanic crust receiving sediments from a continental source, and a Cretaceous stage, which was the development of an island arc.The oceanic-continental isotopic signature of the Arteaga complex is different from other western North American Cordilleran terranes (e.g., Alexander, Wrangelfia) that are more completely "oceanic" in affinity. Nevertheless, the extensive Jurassic(?).Cretaceous arc represents additions of juvenile material to the western North American Cordillera.

  11. Climate in the Western Cordillera of the Central Andes over the last 4300 years

    NASA Astrophysics Data System (ADS)

    Engel, Zbyněk; Skrzypek, Grzegorz; Chuman, Tomáš; Šefrna, Luděk; Mihaljevič, Martin

    2014-09-01

    The Distichia peat core obtained in the Carhuasanta valley near Nevado Mismi, Cordillera Chila, provides information on climatic and environmental conditions over the last ˜4300 years. The relative changes in the stable carbon isotope composition of plant remains preserved in the core reflect major temperature fluctuations in the Western Cordillera of the southern Peruvian Andes. These temperature variations can be additionally linked with the changes in precipitation patterns by analysing C% and C/N ratio in the core. Relatively warm and moist conditions prevailed from 4280 to 3040 cal. yrs BP (BC 2330-1090) with a short colder dry episode around 3850 cal. yrs BP (BC 1900). The most prominent climate changes recorded in the peat occurred between 3040 and 2750 cal. yrs BP (BC 1090-800) when the initial warming turned to a rapid cooling to temperatures at least 2 °C lower than the mean for the Late Holocene. Initially drier conditions within this event turned to a short wet phase after 2780 cal. yrs BP (BC 830) when the temperature increased again. This event coincides with significant changes in peat and ice core records in the Central Andes matching the timing of the global climate event around 2.8 cal. ka BP. Climatic conditions in the study area became relatively dry and stable after the event for about 800 years. Highly variable temperatures and humidity prevailed during the last 2000 years when an extended warm and relatively humid period occurred between 640 and 155 cal. yrs BP (AD 1310-1795) followed by predominantly colder and drier conditions. The established δ13C peat record represents the first continuous proxy for the temperature in the southern Peruvian Andes dated by the AMS 14C. Distichia peat is wide spread in the Andes and the proposed approach can be applied elsewhere in high altitudes, where no other traditional climate proxies are available.

  12. Cenozoic sedimentary and deformational history of hispaniola, 1: southeastern Cordillera Central

    SciTech Connect

    Heubeck, C.; Mann, P.

    1988-01-01

    The Cordillera Central approximates an elongate (220 km), elevated (>3 km), thrust-bounded anticline cored by Cretaceous-Paleogene arc rocks and uplifted during Miocene to recent time by convergent strike-slip movements between the North American and Caribbean plates. The southeastern termination of the anticline plunges beneath a thick (>6 km), well-exposed marine clastic sedimentary sequence. Because uplift-related faulting is minimal in this hinge region of the Cordillera Central anticline, the authors have carried out detailed mapping of the area to determine (1) relation of Cretaceous-Paleogene arc basement to overlying Cenozoic sedimentary cover, and (2) Cenozoic deformational history of arc and basin sequences. Mapping has clearly distinguished three superimposed Cenozoic basins lying on arc basement. The lowest basin (basin 1) is Paleocene-Eocene in age and consists of alternations of arc-derived turbidies with interbedded pelagic limestone and red mudstone. In apparent conformity above this basin is an approximately 4-km thick marine clastic sequence of medial Eocene through early Miocene age (basin 2). These sediments consist of fining-upward turbiditic sequence derived from the northwest and northeast. Arc basement and overlying basins 1 and 2 were shortened approximately 25% in a short-lived, northwest-southeast-directed compressional event that resulted in the formation of large open synclines and tightly folded and faulted anticlines with fold amplitudes of 1-6 km. Underformed, medial Miocene sediments of a mixed clastic and carbonate shelf facies (basin 3) unconformably overlie the folded latest Oligocene-early Miocene rocks of basin 2 and thus constrain the age of folding as early to middle Miocene.

  13. Isotopic characteristics of mantle sources for Quaternary continental alkaline magmas in the northern Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Carignan, Jean; Ludden, John; Francis, Don

    1994-12-01

    Three mantle compositions are identified as potential source end members for Quaternary to recent alkaline volcanic rocks from Fort Selkirk, Llangorse-Hirschfeld, Alligator Lake and Mt. Edziza in the northern Canadian Cordillera. These are: (1) an amphibole-rich source, characterized by unradiogenic Sr, Nd and Pb, from which the olivine nephelinite lavas formed, (2) the continental lithospheric mantle which is characterised by high Pb-207/Pb-204 and appears to be involved in the formation of the alkali olivine basalts of Fort Selkirk, and (3) a mantle with radiogenic Pb and unradiogenic Sr (HIMU-type) represented by lavas from Mt. Edziza. The Mt. Edziza volcano is the largest of the volcanic centres in the region, and is considered to reflect melting of sublithospheric mantle of HIMU composition below central British Columbia. Incipient melting of amphibole-veined subcontinental mantle lithosphere resulted from plume upwelling and/or transtensional pressure release and produced the small nephelinite to olivine basalt centres of the northern Cordilleran Province. The source of the nephelinite magmas is slightly more radiogenic than present-day Pacific Mid-Ocean ridge basalts (MORB), and is best represented by the most depleted component of the Aleutian magmas. This suggests enrichment of the subcontinental lithosphere in the northern Cordillera by melts of this isotopic composition during Cretaceous subduction. The Alligator Lake complex is anomalous and charaterized by the most radiogenic lavas. Despite the presence of crustal xenoliths there is no clear geochemical signature for crustal contamination and, in contrast to the other volcanic centers which were erupted through the Intermontain Belt, the lavas of this center may have been derived from a highly radiogenic lithospheric mantle beneath the Coast Plutonic complex.

  14. Sources and pathways of stream generation in tropical proglacial valleys of the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Gordon, Ryan P.; Lautz, Laura K.; McKenzie, Jeffrey M.; Mark, Bryan G.; Chavez, Daniel; Baraer, Michel

    2015-03-01

    Tropical glaciers supply approximately half of dry-season stream discharge in glacierized valleys of the Cordillera Blanca, Peru. The remainder of streamflow originates as groundwater stored in alpine meadows and other proglacial geomorphic features. A better understanding of the hydrogeology of alpine groundwater, including sources, storage zones, and the locations and magnitudes of contributions to streamflow, is important for making accurate estimates of glacial inputs to the hydrologic budget, and for our ability to make predictions about future water resources as glaciers retreat. This field study focuses on two high-elevation meadows in valleys of the Cordillera Blanca, in headwaters and mid-valley locations. Tracer measurements of stream and spring discharge and groundwater-surface water exchange were combined with synoptic sampling of water isotopic and geochemical composition in order to characterize and quantify contributions to streamflow from different groundwater reservoirs. At the headwaters site, groundwater supplied approximately half of stream discharge from a small meadow, with most originating in an alluvial fan adjacent to the meadow and little (6%) from the meadow itself; however, at the mid-valley site, where meadows are extensive, local groundwater has a large impact on streamflow and chemistry through large net contributions to discharge and turnover of surface water due to gross exchanges with groundwater. At the mid-valley site, stream discharge increased by 200 L s-1 (18% of average discharge) over 1.2 km as it descended a moraine between two meadows. Such valley-crossing moraines, which create significant steps in the down-valley slope, are likely locations of substantial groundwater contribution to streams.

  15. Asymmetrical Growth of Footwall Topography in the Cordillera Blanca, Peru: Implications for Normal Fault Control on Landscape Evolution

    NASA Astrophysics Data System (ADS)

    Giovanni, M. K.; Horton, B. K.

    2007-12-01

    Morphometric parameters and hypsometry of the >5-km-high Cordillera Blanca in Peru provide insights into the topographic evolution of the uplifted footwall of an active, high-magnitude-slip, low-angle normal fault within a contractional orogenic belt. The modern tectonic activity, mappable fault trace, high relief, and uniform footwall lithology make the Cordillera Blanca an ideal locality to test models for the evolution of topography related to normal faulting. Most models for normal fault growth suggest a tectonic and geomorphic symmetry in which maximum slip and maximum surface uplift occur along the central segments of the fault, with net slip, footwall uplift, and hangingwall subsidence diminishing along strike toward the fault tips. A digital elevation model (DEM) of the Cordillera Blanca permits extraction of important geomorphic metrics for footwall transverse drainages and the hanging-wall axial river, including hypsometry, drainage area, drainage length, relief, channel gradient, surface slope, aspect ratio, and longitudinal profile. These data reveal a pronounced asymmetry in which footwall relief, exposed fault relief, channel gradient, and surface slope are greatest along the northern fault segment and become systematically lower southward along strike. In contrast to most models for normal fault growth, largely based on late Cenozoic systems in the Basin and Range province of the western United States, the Cordillera Blanca demonstrates that abrupt and significant along-strike variations in displacement and footwall uplift are possible in major normal fault systems. The causes of an asymmetric distribution of fault slip and footwall topography in the Cordillera Blanca may be related to: (a) mechanical coupling between the subducting flat Nazca slab and the overriding South American plate; (b) gravitational collapse of overthickened crust along reactivated thrust faults; (c) climatic processes linked to the effect of glacial erosion in the footwall

  16. K-Ar dates from the Altiplano and Cordillera Oriental of Bolivia: implications for Cenozoic stratigraphy and tectonics

    NASA Astrophysics Data System (ADS)

    Kennan, L.; Lamb, S.; Rundle, C.

    1995-04-01

    New K-Ar dates from tuffs, lavas and granites, collected in the Bolivian Altiplano and Cordillera Oriental, constrain the evolution of the Bolivian Andes. A phlogopite megacryst from a post-cleavage kimberlite dike near Independencia gave an age of ca. 98 Ma. In the central Altiplano, a widespread suite of basaltic to andesitic lavas, sills and rhyolitic tuffs has yielded dates of 25-22 Ma, coeval with the first major influx of conglomerates in the central Altiplano basin. Rapid early Miocene erosion of the Cordillera Oriental is suggested by biotites from the Quimsa Cruz Granite in the Cordillera Oriental, which vary in age between 32-22 Ma, and also by zircon fission track data. Gentle folding in the Cordillera Oriental near Potosi pre-dates the early Miocene Mondragon Formation which contains a ca. 19 Ma ignimbrite near its base. Further folding here occurred prior to the eruption of the flat-lying ca. 7 Ma ignimbrites of the Condor Nasa Meseta and ca. 12 Ma ignimbrites from the central Los Frailes Meseta. Intense folding in the central Altiplano also occurred between 9 Ma and 5 Ma, and younger tuffs are only slightly tilted. In the Cochabamba region, sedimentary infill of the Parotani Basin contains a ca. 20 Ma tuff horizon, and folded tuffs from the nearby Sacaba Basin have been dated at ca. 2.2 Ma. These ages suggest a protracted history for associated basin-margin ESE sinistral strike-slip and normal faults. However, regional folding pre-dates the San Juan del Oro Surface, which formed an extensive flatlying peneplain, preserved at ca. 3000 m in the central and eastern Cordillera Oriental. The age of valley-fill tuffs suggest that dissection of this surface had commenced in the Cochabamba region by 6.5 Ma. However, near Sucre, flat-lying tuffs, dated between 3.5 and 1.4 Ma, mantle the surface and predate the deep Pleistocene dissection of the central Cordillera Oriental. Deformation has been concentrated in the Subandean foreland thrust belt since the

  17. New geochronological control for the tectono-magmatic evolution of the metamorphic basement, Cordillera Real and El Oro Province of Ecuador

    NASA Astrophysics Data System (ADS)

    Aspden, J. A.; Harrison, S. H.; Rundle, C. C.

    1992-08-01

    Some 150 new isotopic age determinations on metamorphic rocks from the Cordillera Real and parts of El Oro Province in Ecuador, using K-Ar, Rb-Sr, and Sm-Nd methods, help to clarify a complex succession of magmatic and tectonic events. The earliest regional metamorphic/plutonic event recognized, from the Tahuin Group in El Oro, is dated as between ca. 220 and 200 Ma (Late Triassic-Early Jurassic). Similar but less well constrained ages were also obtained from orthogneisses of the Sabanilla and Tres Lagunas subdivisions in the Cordillera Real. Major calc-alkaline granitoids were emplaced ca. 190-150 Ma (Middle-Late Jurassic) in the eastern part of the Cordillera Real, to the north of 2°S, and throughout the sub-Andean zone. Between ca. 140 and 120 Ma (Early Cretaceous), the Oriente region was uplifted and eroded and the Cordillera was affected by an important shearing (dynamothermal) event which results in the resetting of older plutonic ages. From ca. 20 to 85 Ma, conditions were relatively stable, but during ca. 85 to 65 Ma (Late Cretaceous), the Cordillera and Oriente were again uplifted. This uplift corresponds to a second widespread thermal overprinting, which produced a regional disturbance in the K-Ar isotopic systems. Throughout the Cordillera, a number of generally small, undeformed, dominantly lower Tertiary plutons are also present. A few older ( i.e., pre-Mesozoic) dates have been obtained but their interpretation remains uncertain.

  18. Liver transplantation in Spain.

    PubMed

    de la Rosa, Gloria; Fondevila, Constantino; Navasa, Miquel

    2016-09-01

    Liver transplantation (LT) activity started in Spain in 1984 and has exceeded 23,700 interventions, with more than 1000 transplants performed yearly. Every hospital needs official authorization to perform a LT, which implies the obligation to register all patients on the national waiting list. The Spanish National Transplant Organization (ONT) provides essential support for organ procurement, allocation, and management of the waiting list at a national level. Liver allocation is center-oriented as all available organs are referred to the ONT for the whole country. The allocation rules for LT are made according to disease severity after consensus among professionals from every transplant center and ratified by representatives of the regional health authorities. Authorization and location/distribution of transplant centers are regulated by the country (Spain) and by the different regions according to the Real Decreto 1723/2012. For a total population of 47,850,795 inhabitants, there are 24 centers for LT for adults (1 team/2 million people) and 5 for LT for children (1 team/9.5 million people). Nonbiliary cirrhosis, particularly alcohol- and hepatitis C virus-related cirrhosis (60%), and tumors, mainly hepatocellular carcinoma (19%), are the most common indications for LT in Spain. Unusual causes of LT include metabolic diseases like Wilson's disease, familial amyloid polyneuropathy and hyperoxaluria type I, polycystic kidney and liver disease, and some tumors (epithelioid hemangioendothelioma and neuroendocrine tumors). Important efforts are now being undertaken to improve the quality and transplantability of extended criteria livers, in particular those arising from DCD, which represent the greatest opportunity to expand the donor pool. These efforts have to be addressed to adapt the organ preservation procedures, be it through the application of regional perfusion in situ or the use of machine perfusion preservation ex situ. Liver Transplantation 22 1259-1264 2016

  19. [Suicide in Spain today].

    PubMed

    Ruiz-Pérez, Isabel; Olry de Labry-Lima, Antonio

    2006-03-01

    Spain presents one of the lowest suicide rates (8.7 per 100,000) but, as well as Ireland, it has also experienced one of the highest rate increases both within Europe and within the world. In our country, it can be observed an increase in the suicide rates from 1975 to 1994, being this increase greater in men than in women. It can also be noted that there was a stabilisation in the following years. Social factors, specially those which have to deal with gender roles and changes in these roles, are the most common explanations. Another possible explanation for the observed increase in mortality due to suicide among young men could be the AIDS epidemic and intravenous drug addiction, that was observed in Spain during the eighties and nineties. Furthermore, we are witnessing an epidemic related to violence against children and women. Literature strongly suggests that child abuse (psychological and sexual) is associated with increased suicide risk in adolescent or adult life. Women experience violence from their intimate partners and have a greater risk of suffering from chronic pain, diverse somatisations, greater substance use like drugs and alcohol, depression and suicide attempt. The association between work precariousness and suicide seems to be due to economic and social and family support factors, which can lead to greater vulnerability to mental health problems. These factors are of great relevance, since Spain presents one of the highest unemployment and temporary employment rates in the European Union. It seems reasonable that, due to the individualism that characterises the contemporary society, its demands and the new role of women in the work market that cause, among others, a greater difficulty in combining work and family life, are factors that could explain the lack of decrease in suicide rates.

  20. Surgery in Spain.

    PubMed

    Trias, M; Targarona, E M; Moral, A; Pera, C

    1998-02-01

    The Iberian Peninsula-the southwestern point of Europe, between the Mediterranean Sea and the Atlantic Ocean-was visited and settled in ancient times by a variety of peoples. Phoenicians, Carthaginians, Celts, Greeks, Romans, Visigoths, and Arabs all left their mark on the peninsula, and their cultures blended together to found, among other things, a rich tradition in medicine and surgery. During the Renaissance, the fluid exchange of technical skills and knowledge with the rest of Europe and the emergence of universities ensured the development of a high level of medical expertise. Today, surgery in Spain is at the forefront of innovations in the field.

  1. [Resident foreigners in Spain].

    PubMed

    Solana, A M; Pascual De Sans, A

    1994-01-01

    The authors review trends in the size of the resident foreign population in Spain over time since the 1940s. A continuing growth over time, with temporal fluctuations, is noted, with a rapid rise in immigration in the 1980s, leading to new legislation designed to control immigration in 1985-1986 and 1991. The authors note that Europeans, particularly from countries of the European Union, make up a large percentage of the foreign population, but that the number of immigrants from developing countries has increased significantly in the last 10 years.

  2. Negotiated Program Evaluation in Spain.

    ERIC Educational Resources Information Center

    Saez Brezmes, Maria J.; Carretero, Antonio J.

    A concise overview is provided of the history of evaluation, focusing on educational evaluation, followed by some observations on program evaluation in Spain and possible future developments. Evaluation was a new concept in Spain at the end of the Franco era, at a time when its development was beginning to gain momentum in the United States. The…

  3. Early Childhood Inclusion in Spain

    ERIC Educational Resources Information Center

    Giné, Climent; Balcells-Balcells, Anna; Cañadas, Margarita; Paniagua, Gema

    2016-01-01

    This article describes early childhood inclusion in educational settings in Spain. First, we address the legislative framework of preschool education in Spain and offer a brief analysis of some relevant issues, including the current situation of early childhood education and inclusion at this stage. Second, current policies and practices relating…

  4. Early Childhood Inclusion in Spain

    ERIC Educational Resources Information Center

    Giné, Climent; Balcells-Balcells, Anna; Cañadas, Margarita; Paniagua, Gema

    2016-01-01

    This article describes early childhood inclusion in educational settings in Spain. First, we address the legislative framework of preschool education in Spain and offer a brief analysis of some relevant issues, including the current situation of early childhood education and inclusion at this stage. Second, current policies and practices relating…

  5. Multifunctional "Se": Course of Development in Spanish Children.

    ERIC Educational Resources Information Center

    Gathercole, Virginia C.

    A study explored the acquisition of "se" by Spanish-speaking children in Madrid, Spain, looking at: (1) acquisition of multifunctional forms; and (2) the course of acquisition for a linguistic expression that has both anaphoric and non-anaphoric functions, and its relevance to Binding Theory approaches to the acquisition of reflexives.…

  6. Pavlov in Spain.

    PubMed

    Bandrés, Javier; Llavona, Rafael

    2003-11-01

    Reflexology has been present throughout Spanish science since the last third of the nineteenth century and its importance can be seen in the works of authors such as Martín Salazar, Ramón y Cajal, Gómez Ocaña, Simarro and Turró. The most important research in Reflexology in Spain takes place a) at the Schools of Neurophysiology and Psychology in Barcelona and Madrid, b) with a group of authors specializing in pathological medicine and c) in the Military's Health Department, Pavlov's work was received in Spain with special interest. Fernández-España, who could be considered the "first Spanish Pavlovian," emphasized Pavlov's work in a series dedicated to the study of objective psychology which was published between 1914 and 1924. Planelles was the first investigator to develop a program in pavlovian experimentation, presenting his results in 1935. The Civil War (1936-1939) ended these and many other Spanish projects in psychology. After the war, interest in Reflexology and Pavlov's theories slowly rose again, first through psychosomatic medicine and then in the 60's because of the works of such authors as Monserrat-Esteve, Rof Carballo and Colodrón. The progressive inclusion of psychology in the Schools of Philosophy and Arts after 1968 marked the beginning of a new era.

  7. Thermal and exhumation history of the Coastal Cordillera arc of northern Chile revealed by thermochronological dating

    NASA Astrophysics Data System (ADS)

    Juez-Larré, Joaquim; Kukowski, Nina; Dunai, Tibor J.; Hartley, Adrian J.; Andriessen, Paul A. M.

    2010-11-01

    The thermal and erosional history of convergent plate boundaries is important for understanding the links between subduction, arc magmatism, genesis of ore deposits, topography and climate of orogenic belts. Unlike the continent-continent collision that formed many of the largest orogenic belts known today, the Central Andes of South America is a unique case where an oceanic-continent collision has given rise to the Earth's longest and second tallest orogenic belt. Over the last thirty years a plethora of models have been suggested in an attempt to explain how a plateau-type orogen formed at the leading edge of western South America. In the Central Andes most research have focussed attention on the study of the evolution of the arc and backarc, since continuous subduction erosion of the forearc has left little trace of the interplate dynamics that initiated the orogenic belt. In this article, we present a new insight into the thermal and exhumation history of the forearc along the Coastal Cordillera of northern Chile based on biotite K-Ar, apatite fission-track, and apatite/zircon (U-Th)/He dating. We collected diorite samples in a 2 km thick crustal section at the coastal cliff (~ 22°S), and a sea level isoelevation profile between 21 and 27°S. Results from all three dating methods show that the cooling of Coastal Cordillera took place shortly after emplacement during a period of rifting in Jurassic times. Cooling took place in two episodes, mainly in Late Jurassic-Early Cretaceous (~ 118-152 Ma) but also during Late Cretaceous (60-80 Ma) due to the resumption of compression, rift closure, arc uplift, exhumation, eastward migration of magmatic arc activity, and thermal relaxation. The youngest apatite (U-Th)/He ages reveal a cooling event, never reported previously, between 40 and 50 Ma (Eocene). This thermal event affected a > 500 km long and > 1 km thick section of the Coastal Cordillera in northern Chile. Rock cooling recorded in the Eocene cannot be

  8. Diversity and abundance of forest frogs (Anura: Leptodactylidae) before and after Hurricane Georges in the Cordillera Central of Puerto Rico

    USGS Publications Warehouse

    Vilella, F.J.; Fogarty, J.H.

    2005-01-01

    Caribbean hurricanes often impact terrestrial vertebrates in forested environments. On 21 September 1998, Hurricane Georges impacted Puerto Rico with sustained winds in excess of 166 km/hr, causing damage to forests of the island's principal mountain range; the Cordillera Central. We estimated forest frog abundance and diversity from call counts conducted along marked transects before and after Hurricane Georges in two forests reserves of the Cordillera Central (Maricao and Guilarte). We used distance sampling to estimate density of Eleutherodactylus coqui and recorded counts of other species. After the hurricane, the abundance of E. coqui increased in both reserves compared to prehurricane levels while abundance of other frog species decreased. In Maricao, relative abundance of E. richmondi (P = 0.013) and E. brittoni (P = 0.034) were significantly lower after the hurricane. Moreover, species richness and evenness of the Maricao and Guilarte frog assemblages declined after the hurricane. Our results on abundance patterns of the forest frog assemblages of Maricao and Guilarte Forests were similar to those reported from the Luquillo Experimental Forest after Hurricane Hugo in September 1989. Long-term demographic patterns of the forest frog assemblages in the Cordillera Central may be associated with changes due to the ecological succession in post-hurricane forests. Copyright 2005 College of Arts and Sciences.

  9. Calibration and Assessment of a Distributed Hydrologic Model Applied to a Glacierized Basin in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Burns, P. J.; Nolin, A. W.; Lettenmaier, D. P.; Clarke, G. K.; Naz, B. S.; Gleason, K. E.

    2011-12-01

    Glacier retreat has been well documented in the Cordillera Blanca of the Peruvian Andes. It is becoming clearer that changes in glacier area and volume will negatively affect water resources in this region, particularly during the dry season (May to September). Previous studies focusing on this issue in the Cordillera Blanca have had success modeling runoff but did so using somewhat over-simplified hydrologic models. The question driving this study is: How well does the Distributed Hydrology Soil and Vegetation Model (DHSVM) coupled with a new dynamic glacier sub-model replicate runoff in a test basin of the Cordillera Blanca, namely Llanganuco. During the 2011 dry season we collected data on stream discharge, meteorological conditions, soil, and vegetation in the basin. We installed two stage height recorders in the middle reaches of the watershed to complement a third which delineates the basin outlet. Flow data collected at these points will be used for model calibration and/or validation. For geochemical validation we collected spring and meltwater samples for use in a two component isotopic mixing model. We also mapped dominant soil and vegetation types for model input. We use satellite imagery (ASTER and Landsat) to map the change in glacier extent over approximately the last 30 years as this will be another model input. Coupled together, all of these data will be used to run, validate, and refine a model which will also be implemented in other regions of the world where glacier melt is crucial at certain times of the year.

  10. Transgressive stratigraphy, anoxia, and regional correlations within the late Precambrian Windermere grit of the southern Canadian Cordillera

    SciTech Connect

    Ross, G.M.; Murphy, D.C.

    1988-02-01

    The Windermere grit system in the southern Canadian Cordillera comprises the depositional record of a late Precambrian continental basin of uncertain tectonic affinity. Attempts to analyze the basin by means of these largely nonfossiliferous turbiditic rocks have been frustrated by a lack of chronostratigraphic marker units, a problem common in Precambrian sedimentary sequences. Stratigraphic analysis and regional mapping in the Cariboo Mountains (southeastern Canadian Cordillera) suggest that comparison of Precambrian sequences with Phanerozoic analogues holds promise for constructing chronologically significant sea-level lithostratigraphy. In the Cariboo and western Rocky mountains, a distinctive upward-thinning, dominantly pelitic succession (120 m thick) of rhythmic marble-silty pelite that is capped by a 20-m-thick carbonaceous sulfidic pelite represents a dramatic departure from sandy turbidite deposition and is interpreted as the depositional response of the turbidite system to eustatic sea-level rise. This marker unit appears to persist throughout Windermere grits in the southern Canadian Cordillera and, by analogy with well-constrained Phanerozoic examples of black shale deposition, is inferred to represent a synchronous basinwide highstand event. When analyzed within the context of black-shale depositional models, facies variations within the marker unit provide important constraints on basin shape, possibly water depth, and the magnitude of transcurrent fault movement in the southern Rocky Mountain trench.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  12. New insights on the crustal thickness and its lateral variations beneath the Rif Cordillera

    NASA Astrophysics Data System (ADS)

    Gil de la Iglesia, A.; Diaz Cusi, J.; Gallart, J.; Carbonell, R.; Harnafi, M.; Levander, A.

    2014-12-01

    The Rif cordillera forms, together with the Betic ranges, one of the tightest orogenic arcs on Earth. This continental boundary zone is dominated now by the slow convergence between Nubia and Eurasia, but with clear evidences of extensional tectonics. One of the missing elements to constrain the complex geodynamics of the Gibraltar Arc System is the knowledge on crustal structure beneath northern Morocco. In the last decade a major effort has been done in this sense, from active and passive seismics. We compile here the recent results available from the Rif domains. Two 330 km long wide angle DSS profiles were recorded end of 2011 across the Rif in NS and EW transects within the Rifsis project, complemented by onshore recordings of the Gassis-WestMed marine profiles. At the same period, BB seismic arrays were deployed in the area within Topo-Iberia and Picasso projects, allowing receiver function analyses of crustal depths. The ray-tracing modeling of the Rifsis profiles reveal a large Moho step and an area of crustal thickening both in EW and NS directions, grossly coincident with the Bouguer gravity anomalies. The deployment logistics allowed that all the stations recorded all the shots, thus providing useful offline data. We will use here all available in-line and offline data to provide a map of the crustal thickness in northern Morocco. We combined two approaches: i) a hyperbolic time reduction applied to the seismic data, resulting in low-fold stacks in which the reflections from the Moho should appear as subhorizontal lines; ii) the arrival times of the observed PmP phases allow, assuming a mean crustal velocity, to assign a midpoint crustal thickness to each lecture. Although some uncertainties may be inherent to those approaches, a large crustal root, reaching more than 50 km, is well documented in the central part of the Rif Cordillera, close to the zone where the Alboran slab may still be attached to the lithosphere. We also compared these results with

  13. Historical and future hydrologic response to glacier recession in the Cordillera Real, Bolivia

    NASA Astrophysics Data System (ADS)

    Frans, C. D.; Istanbulluoglu, E.; Naz, B.; Lettenmaier, D. P.; Condom, T.; Clarke, G. K.; Burns, P. J.; Nolin, A. W.

    2013-12-01

    In many partially glaciated watersheds climate-forced glacier recession has altered and will continue to alter seasonal water availability, leading to profound implications for water supply systems. The tropical glaciers of the Cordillera Real, Bolivia, whose melt water significantly contributes to water supply and energy production for the densely populated La Paz area, have retreated at unprecedented rates since the 1970's. This glacier recession will continue with ongoing increasing temperatures projected for the subtropical Andes. We use a recently developed glacio-hydrological model to evaluate the contribution of glacier melt to watershed discharge, and track this contribution in time with changing glacier area. A glacier model, solving time-evolving and spatially-distributed balance equations for glacier mass and momentum, is integrated within the Distributed Hydrology Soil Vegetation Model (DHSVM). The glacio-hydrologic behavior of Cordillera Real watersheds is simulated during the historical period of 1987-2010. This model application is validated through comparisons with satellite derived glacier extent estimates and in-situ mass balance, surface energy flux, and stream discharge measurements. The retrospective analysis indicates that glacier melt contributed, on average, 31% (63%) of total annual (dry season-JJA) watershed discharge. Further, the modeling approach is used to predict the transitioning contribution of glacier melt and watershed hydrology through the 21st century. Multiple realizations of the 21st century meteorological data, used to force the glacier-hydrological model, are produced using a stochastic statistical downscaling technique. In this technique a weather generator (Advanced Weather Generator, AWE-GEN) is employed with statistical parameters of the future climate obtained from predictions of 11 CMIP5 general circulation models (GCMs). Future simulations indicate a 17% (23%) decrease in annual (JJA) runoff by the end of the 21st

  14. New tools for integrative thermochronology, and their application to the Colombian Eastern Cordillera

    NASA Astrophysics Data System (ADS)

    Ketcham, R. A.; Mora, A.; Almendral, A.; Parra-Amezquita, M.; Casallas, W.; Robles, W.

    2013-12-01

    We present two new tools for interpreting thermochronometric data that facilitate the joint use of multiple samples to better constrain thermal history, and demonstrate their utilization in the Colombian Eastern Cordillera. The first, Fetkin, is a finite element solver that takes as input a series of detailed balanced cross sections created using dedicated software such as (2D)Move, and solves the heat flow equation in 2D along with predicted thermochronometric ages which can be compared against measured data. It also performs an independent analysis of the cross sections and flags aspects that are structurally out of balance. It is distinguished from similar tools in 2D and 3D principally by providing a level of detail that allows for investigation of samples in very specific and complex structural contexts, and a workflow that allows the interpreter to engage in successive refinements of the structural model using the inferences provided by thermochronometric data. The second tool is a new set of functionality in HeFTy for inverse modeling of thermochronometric data that allows for simultaneous modeling of samples down a well or borehole. This extension forces attention on issues that have previously been relatively neglected in such modeling, in particular that of multiple provenance. It is axiomatic that mineral grains in different strata may have come from different regions and have different inherited thermal histories. Interpreting such data in a realistic geological context thus requires allowing for different inherited populations within and between samples. The rewards in doing so include more robust modeling and interpretation and, in some cases, insights concerning the unroofing histories of the source rocks that contributed to a given sedimentary unit. Similarly, the mutual constraints imposed by modeling multiple samples with known or constrained depositional and structural context considerably amplifies the resolving power of thermochronometric data

  15. Integrative computational tools for interpreting thermochronometric data: Application to the Colombian Eastern Cordillera

    NASA Astrophysics Data System (ADS)

    Ketcham, R. A.; Mora, A.; Almendral, A.; Parra, M.; Cassalas, W.; Robles, W.

    2011-12-01

    We present two new computational tools for interpreting thermochronometric data that facilitate the joint use of multiple samples to better constrain thermal history, and demonstrate their utilization in the Colombian Eastern Cordillera. The first, Fetmove, is a finite element solver that takes as input a series of detailed balanced cross sections, as created using a dedicated software package such as (2D)Move, and solves the heat flow equation in 2D along with predicted thermochronometric ages which can be compared against measured data. It is distinguished from similar tools in 2D and 3D principally by providing a level of detail that allows for investigation of samples in very specific and complex structural contexts, and a workflow that allows the interpreter to engage in successive refinements of the structural model using the inferences provided by thermochronometric data. The second tool is a new set of functionality in the HeFTy software for inverse modeling of thermochronometric data that allows for simultaneous modeling of samples down a well or borehole. This extension forces attention on issues that have previously been relatively neglected in such modeling, in particular that of multiple provenance. It is axiomatic that mineral grains in different strata may have come from different regions and have different inherited thermal histories. The same is frequently true for grains in single specimens, and is a frequent cause of apatite fission-track single-grain ages failing the chi-squared test. Interpreting such data in a realistic geological context thus requires allowing for different inherited populations within and between samples. The rewards in doing so include more robust modeling and interpretation and, in some cases, insights concerning the unroofing histories of the source rocks that contributed to a given sedimentary unit. Similarly, the mutual constraints imposed by modeling multiple samples with known or constrained depositional and

  16. The North American Cordillera - an Impediment to Growing the Continent-wide Laurentide Ice Sheet

    NASA Astrophysics Data System (ADS)

    Löfverström, M.; Liakka, J.; Kleman, J.

    2015-12-01

    warmer summer temperatures that prevent the westward ice expansion. The climate is also more arid in the lee of the Cordillera, which further helps limit the expansion of the ice sheet. Hence, the present study suggests that the Cordillera played a key role for the spatial evolution of the pre-LGM ice sheet in North America.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  18. Active faulting in the frontal Rif Cordillera (Fes region, Morocco): Constraints from GPS data

    NASA Astrophysics Data System (ADS)

    Chalouan, Ahmed; Gil, Antonio J.; Galindo-Zaldívar, Jesús; Ahmamou, M.'Fedal; Ruano, Patricia; de Lacy, Maria Clara; Ruiz-Armenteros, Antonio Miguel; Benmakhlouf, Mohamed; Riguzzi, Federica

    2014-07-01

    The southern Rif cordillera front, between Fes and Meknes, is formed by the Prerif Ridges, which constitute a thrust and fold belt, in contact with the Saïss foreland basin. Geological evidence and regional GPS network data support recent and active tectonics of this Alpine cordillera, with a top-to-the-S-SW motion with respect to stable Africa. A local non-permanent GPS network was installed in 2007 around Fes to constrain the present-day activity of the mountain front. Six GPS sites are located in the Prerif mountain front (jbel Thratt and jbel Zalarh), the Saïss basin and the foreland constituted by the tabular Middle Atlas. Measurements of the GPS network in 2007, 2009 and 2012, over a five year span, seem to indicate that this region is tectonically active and is subjected to significant horizontal motions: (i) a regional displacement toward the SW with respect to stable Africa, showing an average rate of 2 mm/yr; (ii) a southwestward convergent motion between the jbel Thratt with respect to the Saïss basin and the eastern Zalarh ridge, with an average rate of about 4 mm/yr; and (iii) moderate NNE-SSW divergent dextral motion between the Saïss basin and the northern front of the tabular Middle Atlas with an average rate of about 1-2 mm/yr. The regional southwestward motion is related to the activity of the NE-SW sinistral North Middle Atlas-Kert fault zone, which follows the Moroccan Hot Line. Convergence between the Prerif ridges, located at the southern edge of the Rif, and the Saïss basin is accommodated by ENE-WSW striking northward dipping reverse sinistral faults and south vergent folds. In addition, increasing deformation toward the western ridges is in agreement with the stepped mountain front and the development of the arched structures of the Prerif ridges. Normal faults located south of the Saïss basin are responsible for local extension. Whereas the most active deformation occurs in the southern front of the jbel Thratt near Fes, the Sa

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    The Cambumbia Stock is located on the western flank of the Central Cordillera of the northern Andes. The goals of this study were to petrographic and geochemically characterize the Cambumbia igneous body and to establish its petrogenetic history. 41 samples were collected, 28 for petrographic analysis and 14 for elementary chemical determination by ICP-MS. Petrographically the samples were classified as hornblende and pyroxene-gabbros varying to diorites, gabbronorites and tonalites, the rock texture varies from medium to coarse granular grain, with local microporfiritic texture. It was concluded from the major elements analysis that the samples correspond to the sub-alkaline series with low K content, mainly in the calc-alkaline series, within the gabbros and diorites fields. By using the SiO2 vs TiO2 (Jaramillo, 1980), Th/Yb vs Ta/Yb (Pearce, 1984) (Fig. 1) and Zr/117-Th-Nb/16 (Wood, 1979) diagrams it was determined that these rocks were generated in two geotectonic environments: one type MOR (extension) and other island arc (subduction, compression). Petrographic and geochemical comparisons between the rocks of Cambumbia Stock and Diorite and Gabbro El Pueblito (Giraldo, 2009) (located about 25 km to the north-west) may postulate a possible genetic link between them. Recently, a U/Pb age was obtained by the Universidad de Caldas in zircon in 2009 (not published data), yielded an age of 233.41 ± 3.4 Ma (Middle Triassic). This age is consistent with the global event of the extension and fragmentation of Pangea supercontinent. In addition, the mantle nature of the source and the petrogenetic evolution of the magmatic system were established. References GIRALDO, M.I., (2009): Esquema geodinámica de la parte noroccidental de la cordillera Central de Colombia. (Thesis). p.56-68. Universidad Nacional de Colombia, Medellín. JARAMILLO, J.M. (1980): Petrology and geochemistry of the Nevado del Ruiz Volcano northern Andes, Colombia (Thesis). 167 p. University of Houston

  20. Dual diagnosis in Spain.

    PubMed

    Gual, Antoni

    2007-01-01

    Our aim is to describe the current situation regarding the diagnosis and treatment of addiction in a variety of settings in Spain. Four-hundred and twenty-seven physicians known to treat addicted patients in non-private settings were recruited and agreed to participate. Each physician provided clinical and anonymous information on the first 6 consecutive patients who attended on a scheduled day. A total of 2361 patients were interviewed (92.1%) and data were obtained concerning gender, age, work, educational level, civil status, addiction diagnosis, type of treatment and psychiatric comorbidity. Seven-hundred and ninety-eight out of 2361 addicts (33.8%) presented with a dual diagnosis. Depression was the most prevalent disorder (21.6%), followed by anxiety disorders (11.7%). Comorbidity was found to be related to age, female gender, divorce and widowhood, and higher educational levels. Alcoholics who abused other drugs showed the highest rates of comorbidity (48.5%), while opiate addicts were at the lower end of the spectrum (27.4%). No differences were found related to the treatment setting, the doctor's medical specialty, or the geographical area. Finally, doctors tended to perceive that dual diagnosis was related to a worse psychiatric prognosis but not to higher relapse rates. Antidepressants were the most commonly prescribed drugs (62.4% of co-morbid patients) and anticraving agents were prescribed equally to comorbid and non-comorbid patients. Within the limitations of a descriptive study, our data show that comorbidity is a common clinical problem in patients who access addiction treatment. Affective and anxiety disorders are the most common comorbid diseases, and comorbidity rates seem to be unrelated to regional differences, medical settings or doctor's professional background. Dual diagnosis patients thus account for one third of the clinical workload of addiction specialists in Spain.

  1. Late Triassic, arc-related, potassic igneous rocks in the North American Cordillera

    NASA Astrophysics Data System (ADS)

    Mortimer, N.

    1986-12-01

    Igneous rocks of Late Triassic age are widespread in the Cordillera of western North America and, except in Wrangellia, consist of subduction-related plutonic and volcanic suites. Many of these, including those in the Stikinia, Quesnellia, Rattlesnake Creek, and Jackson terrenes and in southern California, are clinopyroxene rich and belong to high-potassium and shoshonitic rock series, features that are generally absent from older and younger igneous rocks in the same terranes. The Late Triassic subduction-related rocks are exposed in two discontinuous belts that lie east and west of the Cache Creek terrane in Canada and correlative melange terranes farther south. Stratigraphic and structural data suggest that these belts were spatially separate magmatic arcs in Late Triassic time. Tectonic implications of this analysis include an explanation of Middle Jurassic Cordilleran deformation as the result of collision of the western with the eastern belt, absence of Late Triassic links between Stikinia and Quesnellia, disassociation of Stikinia with terranes in northwestern Nevada, and tentative correlation of the Wallowa (Seven Devils) terrane with Stikinia rather than Wrangellia. *Present address: New Zealand Geological Survey, Department of Scientific and Industrial Research, Private Bag, Dunedin, New Zealand

  2. The unusual nature of recent snowpack declines in the North American cordillera

    USGS Publications Warehouse

    Pederson, Gregory T.; Gray, Stephen T.; Woodhouse, C.A.; Betancourt, Julio L.; Fagre, Daniel B.; Littell, Jeremy S.; Watson, Emma; Luckman, B.H.; Graumlich, Lisa J.

    2015-01-01

    In western North America, snowpack has declined in recent decades, and further losses are projected through the 21st century. Here, we evaluate the uniqueness of recent declines using snowpackreconstructions from 66 tree-ring chronologies in key runoff-generating areas of the Colorado, Columbia, and Missouri River drainages. Over the past millennium, late 20th century snowpack reductions are almost unprecedented in magnitude across the northern Rocky Mountains and in their north-south synchrony acrossthe cordillera. Both the snowpack declines and their synchrony result from unparalleled springtime warming that is due to positive reinforcement of the anthropogenic warming by decadal variability. The increasing roleof warming on large-scale snowpack variability and trends foreshadows fundamental impacts on streamflow and water supplies across the western United States.

  3. ‘Diffuse faulting’ in the Machu Picchu granitoid pluton, Eastern Cordillera, Peru

    NASA Astrophysics Data System (ADS)

    Mazzoli, Stefano; Vitale, Stefano; Delmonaco, Giuseppe; Guerriero, Vincenzo; Margottini, Claudio; Spizzichino, Daniele

    2009-11-01

    A series of batholiths, forming part of the 'roots' of a Permo-Liassic rift system, are exposed in the high Eastern Cordillera of central Peru as a result of tectonic inversion. Shortening of the Machu Picchu granitoid pluton was accommodated by widespread shear reactivation of primary joints, by a process termed here 'diffuse faulting'. Fault-like reactivation of precursor joint surfaces, marked by chlorite, epidote and quartz shear fibres, is locally evidenced by few centimetres offsets within apparently undeformed granite. Analysis of fault slip data indicates that shear reactivation of different joint sets was kinematically consistent with ENE oriented shortening. Less frequent mylonitic shear zones appear to have evolved from the common brittle precursors. Apart from rare phyllonitic shear zones, fluid-rock interaction along the brittle precursors was generally limited, and pluton deformation appears to be mainly controlled by the geometry and distribution of primary joints. Three main sets of reactivated joints can be recognized, characterized by oblique-slip kinematics with variable reverse and strike-slip components of motion. Theoretical modelling based on quantitative fracture analysis (scan-line data) and different displacement-length relationships applied to the main reactivated joint sets yield first-order estimates of pluton finite strain. The results suggest that bulk finite strain is oblate and essentially coaxial, and is characterized by horizontal shortening not exceeding 10%. Relatively small finite strains, integrated over the size of the pluton, still result in a few kilometres of crustal shortening.

  4. Varve deposition and the sediment yield record at three small lakes of the southern Canadian Cordillera

    SciTech Connect

    Desloges, J.R. )

    1994-05-01

    Lacustrine sediments deposited in three small glacier-fed lakes of the southern Canadian Cordillera are derived primarily from subglacial erosion and delivered via short proglacial streams or by direct melting and calving of cirque glaciers. Sediment transport and deposition during early summer is controlled by runoff-generated bottom currents and in the late summer through winter by settling from suspension. This forms distinct rhythmic laminations of silt and clay in distal lake areas. Cesium-137 content in all three lakes indicates that these are varve sediments. Time series of varve thickness covering the interval 1863 to present show distinct declines in sediment yield from 310 to less than 150 t km[sup [minus]2] a[sup [minus]1]. The decline is related to sediment exhaustion following glacier retreat from Little Ice Age maxima and the opening of intervening sediment storage sites. Annual varve thickness is significantly related to fluctuations in summer or late summer temperature highlighting the importance of ice ablation, melt-water runoff, and subglacial sediment sources in controlling deposition rates. Singular climate events, such as autumn storms provide distinctive sedimentary signatures in the varve record. Reconstructed sediment yield for the Little Ice Age is as much as 100% greater than the average Holocene rate. 39 refs., 8 figs., 2 tabs.

  5. Mid-tertiary volcano-tectonic development of the Southwestern Cordillera of North America

    NASA Technical Reports Server (NTRS)

    Nelson, Kerri L.

    1987-01-01

    In the Southwestern Cordillera (SC) of North America, volcanic style changed from dominantly calcalkaline stratovolcanoes to caldera-related magmatism during the mid-Tertiary. The dominant tectonic process affecting the region during this time was convergence of the Farallon and North American Plates. The change in style of volcanism indicates a change in the operative stress regime: compressional for the earlier calcalkaline volcanism and tensional for development of the calderas. The development of the centers were compared to evaluate the volcano-tectonic relationship of caldera development within and between centers and determine the relationships between the earlier calcalkaline and later caldera-style volcanisms. The calderas exhibit three distinct stages of development that are closely associated with the East Pacific Rise/trench collision. The spatial and temporal association of the calcalkaline and caldera-related volcanism argues for the SC representing a region of continued arc magnetism in which the style of volcanism varied in response to differences in regional stresses.

  6. Serological survey of leptospiral infections in sheep, goats and dogs in Cordillera province, Bolivta.

    PubMed

    Ciceroni, L; Bartoloni, A; Pinto, A; Guglielmetti, P; Valdez Vasquez, C; Gamboa Barahona, H; Roselli, M; Giannico, F; Paradisi, F

    1997-01-01

    A serological survey for antibodies to Leptospira spp. was conducted on sheep, goat and dog serum samples collected in three localities in Cordillera province in the southern part of the Santa Cruz Department (Bolivia) in 1992. A total of 98 sheep, 218 goats and 43 dogs were tested against 29 leptospiral serovars using the microscopic agglutination test. At the time of blood collection all of the examined animals appeared healthy and presented no clinical sign suggestive of leptospirosis. Antibody prevalences, as determined by positive results at a 1:100 dilution or higher, was 14.3% in sheep, 19.7% in goats, and 14.0% in dogs. Agglutinins against six serovars (poi. shermani, pomona, canicola, javanica, djasiman) were found in positive animals. The highest serological prevalence in sheep and goats was recorded for serovar poi, followed by pomona in sheep and shermani in goats. Titres to shermani were the commonest in dogs. The results of this survey indicate that leptospiral infection is common in south-east Bolivia and that serovars of several serogroups concur in the etiology.

  7. Results of land cover change detection analysis in and around Cordillera Azul National Park, Peru

    USGS Publications Warehouse

    Sleeter, Benjamin M.; Halsing, David L.

    2005-01-01

    The first product of the Optimizing Design and Management of Protected Areas for Conservation Project is a land cover change detection analysis based on Landsat thematic mapper (TM) and enhanced thematic mapper plus (ETM+) imagery collected at intervals between 1989 and 2002. The goal of this analysis was to quantify and analyze patterns of forest clearing, land conversion, and other disturbances in and around the Cordillera Azul National Park in Peru. After removing clouds and cloud shadows from the imagery using a series of automatic and manual processes, a Tasseled Cap Transformation was used to detect pixels of high reflectance, which were classified as bare ground and areas of likely forest clearing. Results showed a slow but steady increase in cleared ground prior to 1999 and a rapid and increasing conversion rate after that time. The highest concentrations of clearings have spread upward from the western border of the study area on the Huallaga River. To date, most disturbances have taken place in the buffer zone around the park, not within it, but the data show dense clearings occurring closer to the park border each year.

  8. Recent evolution and degradation of the bent Jatunraju glacier (Cordillera Blanca, Peru)

    NASA Astrophysics Data System (ADS)

    Emmer, Adam; Loarte, Edwin C.; Klimeš, Jan; Vilímek, Vít

    2015-01-01

    This article brings new insight into the recent evolution and degradation of the bent Jatunraju glacier in the northern part of the Cordillera Blanca, Peru. Analysis of topographical maps, aerial photos and satellite images covering a period of 66 years and a field survey performed in June 2013 and May 2014 helped to describe the geomorphological setting and ongoing processes. Recent evolution and degradation processes are also deduced from surface movements. Historical geodetic measurements (1967-1968; 1977-1984) and current LANDSAT images (2001-2013) were used to estimate surface velocities and changes in surface velocities over time. Our investigation showed that the most significant changes happened at an altitude of between 4300 and 4450 m asl. A significant decrease in surface velocities and increase in debris thickness indicate that this part of Jatunraju turned from a debris-covered glacier into an ice-cored rock glacier during the analyzed period. Particular parts of the article describe the cycle of formation and extinction of supraglacial lakes and the melting of buried (debris-covered) ice. A scenario of future evolution is outlined and discussed as well. We assume that ice degradation within the debris-covered glacier will continue and that the altitude of its presence will increase hand-in-hand with the changing environment.

  9. Palaeogeography and relative sea-level history forcing eco-sedimentary contexts in Late Jurassic epicontinental shelves (Prebetic Zone, Betic Cordillera): An ecostratigraphic approach

    NASA Astrophysics Data System (ADS)

    Olóriz, Federico; Reolid, Matías; Rodríguez-Tovar, Francisco J.

    2012-02-01

    The analysis of macroinvertebrate and foraminiferal assemblages from Upper Jurassic (Middle Oxfordian to Lower Kimmeridgian) epicontinental shelf deposits in the Prebetic (Betic Cordillera, southern Spain) reveals the influence of environmental changes. They are expressed as selected parameters in palaeogeographic and stratigraphic trends (litho- and microfacies, faunal composition, taphonomy), which are interpreted in the context of relative sea-level histories. Middle Oxfordian to early Kimmeridgian (Transversarium to Planula Chrones) rocks and faunal assemblages in comparatively distal sectors (distal shelf) show lower sedimentation rates (lumpy lithofacies), and higher proportions of ammonoids, planktic foraminifera, corrasion degree, microboring and encrustation. Landwards, towards the mid-shelf, eco-sedimentary conditions resulted in spongiolithic limestones and marl-limestone rhythmites with local development of microbial-sponge buildups. Greater distance from shore during relative sea-level highs accords with greater: (1) stratigraphic condensation; (2) abundance in ammonoids, planktic foraminifera and nubeculariids; and (3) degrees of corrasion, microboring and encrustation. These trends in faunal composition and taphonomy agree with backstepping phases, increasing ecospace and a longer exposition of shelly remains on the sea bottom. Decreasing distance from shore during relative sea-level lows relates to opposite trends, as evidenced by: (4) increasing terrigenous input and decreasing stratigraphic condensation; (5) impoverishment in ammonoids and planktic foraminifera; and (6) diminution of corrasion, microboring and encrustation. Phases of forestepping/progradation and aggradation, a reduction of ecospace for nekto-planktic organisms, and comparatively rapid burial of shell remains are interpreted to force the recorded trends. An ecostratigraphic approach is used here to correlate and characterise sea-level changes, applying high resolution stratigraphy

  10. Human Gongylonema infection in Spain.

    PubMed

    Illescas-Gómez, M P; Rodriguez Osorio, M; Gómez Garcia, V; Gómez Morales, M A

    1988-03-01

    A case of gongylonemiasis in a 31-year-old woman of Granada, Spain, is reported. The worm, clearly belonging to Gongylonema genus, could not be identified definitively as Gongylonema pulchrum, the species usually described in humans.

  11. Interaction of aqueous Se(IV)/Se(VI) with FeSe/FeSe2: implication to Se redox process.

    PubMed

    Kang, Mingliang; Ma, Bin; Bardelli, Fabrizio; Chen, Fanrong; Liu, Chunli; Zheng, Zhong; Wu, Shijun; Charlet, Laurent

    2013-03-15

    Since reductive precipitation is considered as the most effective way to immobilize (79)Se, interaction of aqueous Se(IV)/Se(VI) with Fe(II)-bearing minerals has received extensive attention. In contrast to the thermodynamic calculations, as well as the prevalence of iron selenide phases observed in soil, sediments and ore deposits, most laboratory experiments have found that Se(0) was the reaction product. In this study, the interaction of Se(IV)/Se(VI) with FeSe/FeSe2 were investigated. The results demonstrate that FeSe and FeSe2 can be oxidized to Se(0) by Se(IV) with relatively fast kinetics, while reaction between Se(VI) and FeSe/FeSe2 only occurs under limited conditions (i.e. in the presence of high ferrous content and higher pH) with much slower kinetics, and there is no evident reaction in most case. Therefore, reduction of Se(IV) by Fe(II)-bearing minerals, in particular by natural occurring minerals, is envisioned to produce Se(0) at the early stage of experiments, rather than FeSe or FeSe2. Due to the formation of bulk Se(0) and its low solubility, the Fe-Se-O-H2O system will maintain redox disequilibrium in laboratory time-scale. This study also reveals that iron selenides, like iron sulfides, have strong reactivity toward Fe(3+). The findings in this study give insight into possible controls on Se redox process. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. First report of oestrosis in aoudad from southeastern Spain.

    PubMed

    Barroso, Patricia; Ruiz-de-Ybáñez, Rocío; Martínez-Carrasco, Carlos; Gens, María J; Escribano, Fernando; Sánchez, Antonio; Pérez, Jesús M

    2017-07-01

    In spring 2016, we analyzed the skull of 44 aoudads (Ammotragus lervia) from Sierra Espuña Regional Park (SE Spain) for the presence of oestrid larvae. Oestrus ovis larvae were found in 27.3% of sampled hosts, with a mean intensity of 1.5 ± 6.1 larvae/per parasitized host (range 1-21). To our knowledge, this is the first report of oestrosis affecting this host species.

  13. From steady-state to climatically driven denudation across the Central Andes - SE Peru

    NASA Astrophysics Data System (ADS)

    Ruiz, G.; Carlotto, V.; Andriessen, P.

    2009-04-01

    To better constrain the orogenic growth of the Andean chain, we investigated the time-Temperature paths of bedrocks from the two morpho-structural highs of the Central Andes that are separated by the vanishing Altiplano, i.e. the Eastern and Western Cordilleras of SE Peru. The Western Cordillera is a volcanic to volcano-detrital chain that developed ~40-35 Ma ago and is characterized by a 4000m high mean altitude whose origin is poorly constrained. Fission-Track data on apatite and zircon crystals extracted from an Eocene pluton yield ages comprised between 24 and 14 Ma, and 38 and 30 Ma respectively. One of the noteworthy aspects of the data is that analyses reveal a steady-state phase of exhumation from the late Eocene to at least the middle Miocene (38-14 Ma) with no disruption of the exhumation path since 38 Ma either by sedimentary burial and/or rapid exhumation. The uplift of the Western Cordillera was thus probably steady since, avoiding the deposition of foreland basin sequences as in the Altiplano region. Further east, Apatite Fission-Track ages are much younger and range between 7.6 and 2.5 Ma for the Eastern Cordillera and between 11.2 and 1.5 Ma for the Sub-Andean Zone. Age-altitude relationships suggest that denudation increased from a more quiescent Late Miocene period to a high rate of 0.8 km/my for the Pliocene. Such abrupt change is supported by a net in sediment accumulation rates in the Andean Amazon Basin but as far as offshore the Amazon fan. A global climate change is usually invoked for high Pliocene rates; however it post-dated a documented period of surface uplift in the Eastern Andes. Denudation patterns are much contrasted across the Andes of SE Peru. The western Cordillera, despite significant topography and deep river valleys in the studied area, still yield information that suggest a steady and slow uplift from the late Eocene until at least the middle Miocene. We thus propose a coupled scenario: first the Andean orographic barrier

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  15. Late Cenozoic Deformation of the Coastal Cordillera, Northern Chilean Forearc, 18- 25°S

    NASA Astrophysics Data System (ADS)

    Allmendinger, R. W.; González, G.; Loveless, J. P.; Carrizo, D.

    2004-12-01

    Overlying the only part of the South American continental crust that is in direct contact with the subducting Nazca Plate, the Coastal Cordillera of northern Chile and southern Peru should provide the most complete geological record of the coupling between the two plates. This record of coupling is exquisitely preserved in the hyperarid Atacama Desert. This preservation is both one of the major advantages and major challenges of working in this region: On the positive side, exposure of geomorphic surfaces is complete and unencumbered by erosion or vegetation, and brittle saline soils preserve subtle deformation features that would quickly be obliterated in more humid environments. On the negative side, ancient geomorphic features are just as fresh as Recent one and the lack of organic material precludes radiocarbon dating, a traditional tool of paleoseismology. During the last several years, we have concentrated on documenting three fundamental characteristics of late Cenozoic forearc deformation: (1) NS shortening on reverse faults striking at a high angle to, and dextral-reverse faults striking oblique to, the continental margin; (2) N-striking normal faults of the forearc and their reactivation, locally, as reverse faults; and (3) extensive suites of tension cracks. Reverse faults striking at a high angle to the margin are present between 19 and 21.5°S, straddling the topographic symmetry plane that marks the axis of the Bolivian orocline. Limited dating of tuffs and surfaces shows that these structures have been active for at least the last 6 Ma. At least 5 of these structures -- Atajaña, Pisagua, Iquique north and south, and Barranco Alto -- cut the Pleistocene marine terraces of the coastal platform, producing 20 to 50 m of vertical offset. A forearc crustal earthquake just south of Pisagua in March 2007 demonstrates that margin parallel shortening continues to the present and that permanent deformation occurs during the interseismic part of the plate

  16. Late Cenozoic Deformation of the Coastal Cordillera, Northern Chilean Forearc, 18- 25°S

    NASA Astrophysics Data System (ADS)

    Allmendinger, R. W.; González, G.; Loveless, J. P.; Carrizo, D.

    2007-12-01

    Overlying the only part of the South American continental crust that is in direct contact with the subducting Nazca Plate, the Coastal Cordillera of northern Chile and southern Peru should provide the most complete geological record of the coupling between the two plates. This record of coupling is exquisitely preserved in the hyperarid Atacama Desert. This preservation is both one of the major advantages and major challenges of working in this region: On the positive side, exposure of geomorphic surfaces is complete and unencumbered by erosion or vegetation, and brittle saline soils preserve subtle deformation features that would quickly be obliterated in more humid environments. On the negative side, ancient geomorphic features are just as fresh as Recent one and the lack of organic material precludes radiocarbon dating, a traditional tool of paleoseismology. During the last several years, we have concentrated on documenting three fundamental characteristics of late Cenozoic forearc deformation: (1) NS shortening on reverse faults striking at a high angle to, and dextral-reverse faults striking oblique to, the continental margin; (2) N-striking normal faults of the forearc and their reactivation, locally, as reverse faults; and (3) extensive suites of tension cracks. Reverse faults striking at a high angle to the margin are present between 19 and 21.5°S, straddling the topographic symmetry plane that marks the axis of the Bolivian orocline. Limited dating of tuffs and surfaces shows that these structures have been active for at least the last 6 Ma. At least 5 of these structures -- Atajaña, Pisagua, Iquique north and south, and Barranco Alto -- cut the Pleistocene marine terraces of the coastal platform, producing 20 to 50 m of vertical offset. A forearc crustal earthquake just south of Pisagua in March 2007 demonstrates that margin parallel shortening continues to the present and that permanent deformation occurs during the interseismic part of the plate

  17. Ophiolites and Continental Margins of the Mesozoic Western U.S. Cordillera

    NASA Astrophysics Data System (ADS)

    Dilek, Y.

    2001-12-01

    The Mesozoic tectonic history of the western U.S. Cordillera records evidence for multiple episodes of accretionary and collisional orogenic events and orogen-parallel strike-slip faulting. Paleozoic-Jurassic volcanic arc complexes and subduction zone assemblages extending from Mexico to Canada represent an East-Pacific magmatic arc system and an accretionary-type orogen evolved along the North American continental margin. Discontinuous exposures of Paleozoic upper mantle rocks and ophiolitic units structurally beneath this magmatic arc system are remnants of the Panthalassan oceanic lithosphere, which was consumed beneath the North American continent. Pieces of this subducted Panthalassan oceanic lithosphere that underwent high-P metamorphism are locally exposed in the Sierra Nevada foothills (e.g. Feather River Peridotite) indicating that they were subsequently (during the Jurassic) educted in an oblique convergent zone along the continental margin. This west-facing continental margin arc evolved in a broad graben system during much of the Jurassic as a result of extension in the upper plate, keeping pace with slab rollback of the east-dipping subduction zone. Lower to Middle Jurassic volcanoplutonic complexes underlain by an Upper Paleozoic-Lower Mesozoic polygenetic ophiolitic basement currently extend from Baja California-western Mexico through the Sierra-Klamath terranes to Stikinia-Intermontane Superterranes in Canada and represent an archipelago of an east-facing ensimatic arc terrane that developed west and outboard of the North American continental margin arc. The Smartville, Great Valley, and Coast Range ophiolites (S-GV-CR) in northern California are part of this ensimatic terrane and represent the island arc, arc basement, and back-arc tectonic settings, respectively. The oceanic Josephine-Rogue-Chetco-Rattlesnake-Hayfork tectonostratigraphic units in the Klamath Mountains constitute a west-facing island arc system in this ensimatic terrane as a

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  19. [Allergenic pollens in Spain].

    PubMed

    Subiza Garrido-Lestache, J

    2004-01-01

    Allergenic pollens that cause rhinoconjuctivitis and/or asthma are those from trees or plants that pollinate through the air (anemophilic pollination) and not through insects (entomophilic pollination). Although pollen grains would seem to be too large to easily reach the intrapulmonary airways, the relationship between pollen counts and the presence of asthmatic symptoms is only too evident. This is probably because the allergens inducing seasonal asthma are not only found within pollen grains but also outside the grains in particles of less than 10 mm that are freely found in the atmosphere. The most important pollens producing pollinosis in Spain are those from cypress trees from January-March, birch trees in April (macizo galaico), Platanus hispanica (March-April), grasses and olive trees from April-June, Parietaria from April-July and Chenopodium and/or Salsola from July-September. By geographical areas, the main cause of pollinosis are grasses in the center and north of the peninsula, olive trees in the south (Jaén, Sevilla, Granada, Córdoba) and Parietaria in the Mediterranean coast (Barcelona, Murcia, Valencia).

  20. Biogerontology research in Spain.

    PubMed

    Solana, Rafael

    2003-08-01

    The article describes the features of biogerontology research in Spain and outlines the research in the biology of ageing, covering a wide spectrum of areas and topics. Research in biogerontology has expanded notably in quality and quantity in the last decades with the development of internationally recognized research groups actively working in the analysis of the complex process of ageing. In the last few years research in ageing has become a priority area in the National Program of Research which has substantially increased funds specifically allocated to biogerontology and biological research on senescence. Despite these improvements, special efforts have to be made not only to consolidate the existing groups but also to facilitate the initiation and development of new research groups in Universities, Hospitals and research institutions with capacity to incorporate trained researchers in this area. It would promote the continuous incorporation of technical and scientific advances in other disciplines to the understanding the biology of ageing and the molecular basis of cellular senescence, that will benefit actual and future ageing population.

  1. Documenting and describing the redox evolution of the Neoproterozoic ocean: lessons from the Canadian Cordillera (Invited)

    NASA Astrophysics Data System (ADS)

    Johnston, D. T.; Poulton, S. W.; Langmuir, C. H.; MacDonald, F. A.; Chen, Z.; Knoll, A.

    2009-12-01

    The geological record of the Neoproterozoic preserves evidence for large-scale perturbations in Earth’s climate and changes in tectonic configuration. During the terminal Proterozoic, and within the context of these changes, Earth’s fluid envelope achieved a level of oxygenation that allowed for the evolution and subsequent radiation of complex multi-cellular life. As such, better constraining the geochemical evolution of the oceans and atmosphere throughout the entire Neoproterozoic will allow for a more mechanistic understanding of the links between changing environmental chemistry and biological innovation. Further, it will provide information on the relative timing of these changes and, where robust dates are available, estimates on the absolute rates of change (both chemical and biological). To this end, our ongoing work has focused on constructing high stratigraphic resolution geochemical records through mixed lithological packages of sedimentary rocks from eastern Alaska and the Canadian Cordillera. Here, we present detailed chemostratigraphic reconstructions of redox sensitive proxies, including Fe-speciation and trace element budgets, that provide an integrated window into Neoproterozoic marine oxidant budgets. These oxidant budgets then allow for the modeling of the relative influence of different aerobic and anaerobic microbial processes on the overall carbon cycle. Taken together, it is this cascade of microbial processes that drives remineralization reactions, the sum of which serves to counter-act organic carbon export, which is ultimately responsible for the buildup of O2. This simple framework serves as the foundation for our interpretation of Neoproterozoic biogeochemistry and informs our view of late Precambrian marine ecosystems. This approach can be further applied to more specific, and perhaps even more anomalous intervals of Neoproterozoic Earth history, including the Cryogenian Bitter Springs event and the Ediacaran Shuram anomaly; both

  2. Mesozoic igneous activity in the southern Cordillera of North America: Implications for tectonics and magma genesis

    SciTech Connect

    Asmerom, Y.

    1988-01-01

    A representative section in Santa Rita Mountains is dated using the zircon U-Th-Pb isotopic method. The oldest unit, the lower member of the Mt. Wrightson Formation, is concordantly dated at 210 {plus minus} 3 Ma. Initial basaltic andesite to andesite volcanism was followed by deposition of red beds and associated volcanic rocks that are dated at 200 Ma. Felsic volcanism and eolian sand deposition may have spanned from 190 to 170 Ma. The Piper Gulch Granodiorite, representing the earliest Mesozoic intrusive equivalent, gives concordant dates of 188 {plus minus}2 Ma. A second cycle of andesite and rhyolitic volcanism and sedimentation is dated at 151 {plus minus} 5 Ma using the whole-rock Rb-Sr isotopic method. The Hovatter Volcanics in the Little Harquahala Mountains, southwestern Arizona is dated at 165 Ma. Whole-rock Rb-Sr isotopic method on the same rocks gives a coherent reset isochron of 70 {plus minus} 3 Ma. A new stratigraphic correlation is proposed based on the dating data. This part of the Cordillera was an uplifted arc terrane during the Early Mesozoic and may have provided volcanic detritus to the Late Triassic Chinle Formation in the Colorado Plateau. The second part deals with magma evolution and crust modification during arc magmatism. Rocks in southeastern Arizona have {sub Nd} values of {minus}3.4 to {minus}6.4, while rocks to the west have {sub Nd} values ranging from {minus}8.5 to {minus}9.2. Combined REE and isotopic data indicate that assimilation of lower crust by mantle melts followed by fractional crystallization took place.

  3. Hydrological and depositional processes associated with recent glacier recession in Yanamarey catchment, Cordillera Blanca (Peru).

    PubMed

    López-Moreno, J I; Valero-Garcés, B; Mark, B; Condom, T; Revuelto, J; Azorín-Molina, C; Bazo, J; Frugone, M; Vicente-Serrano, S M; Alejo-Cochachin, J

    2017-02-01

    In this study, we investigate changes in the glaciated surface and the formation of lakes in the headwater of the Querococha watershed in Cordillera Blanca (Peru) using 24 Landsat images from 1975 to 2014. Information of glacier retreat was integrated with available climate data, the first survey of recent depositional dynamics in proglacial Yanamarey Lake (4600m a.s.l.), and a relatively short hydrological record (2002-2014) at the outlet of Yanamarey Lake. A statistically significant temperature warming (0.21°C decade(-1) for mean annual temperature) has been detected in the region, and it caused a reduction of the glacierized area since 1975 from 3.5 to 1.4km(-2). New small lakes formed in the deglaciated areas, increasing the flooded area from1.8ha in 1976 to 2.8ha in 2014. A positive correlation between annual rates of glacier recession and runoff was found. Sediment cores revealed a high sedimentation rate (>1cmyr(-1)) and two contrasted facies, suggesting a shift toward a reduction of meltwater inputs and higher hydrological variability likely due to an increasing role of precipitation on runoff during the last decades. Despite the age control uncertainties, the main transition likely occurred around 1998-2000, correlating with the end of the phase with maximum warming rates and glacier retreat during the 1980s and 1990s, and the slowing down of expansion of surface lake-covered surface. With this hydrological - paleolimnological approach we have documented the association between recent climate variability and glacier recession and the rapid transfer of hydroclimate signal to depositional and geochemical processes in high elevation Andean environments. This, study also alerts about water quality risks as proglacial lakes act as secondary reservoirs that trap trace and minor elements in high altitude basins.

  4. Infrared Imaging and Modeling of Proglacial Stream Temperature in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Baker, E. A.; Lautz, L.; McKenzie, J. M.; Aubry-Wake, C.; Somers, L. D.; Wigmore, O.; Glose, A.; Glas, R. L.; Mark, B. G.

    2015-12-01

    In the tropical Andes, glacial meltwater is an important water resource for downstream communities, especially during the dry season. Due to climate change, glacial retreat is accelerating and straining already limited water resources in the region. It is hypothesized that groundwater storage and discharge will play a critical role in sustaining future river flows. To improve our understanding of the hydrologic fluxes in proglacial valleys of the tropical Andes, we monitored a ~1.2 km reach of the Quilcayhuanca River, in the Cordillera Blanca, Peru, using a high resolution infrared (IR) camera and in-stream temperature sensors. We positioned the IR camera on the southern valley wall, 96 m above the valley floor, and collected >700 IR images at 10 minute intervals over 5 days. We deployed 40 temperature sensors along the stream at ~25 m intervals and 10 sensors at additional control points throughout the surrounding valley, recording temperature at 10 minute intervals. Groundwater temperature was recorded in 6 wells in the study area. The reach had diurnal temperature fluctuations from ~4 to 13°C, but did not exhibit large longitudinal temperature differences. Stream temperature profiles within the water column show stream water is well mixed, improving the ability of the IR camera to accurately observe the stream temperature at this research site. Temperature sensors in 4 reach tributaries recorded warmer temperatures than the main channel. The daily temperatures of one tributary fluctuated within the range of the groundwater temperature (~9 to 11°C), while another tributary exhibited a range of ~18°C. A weather station in the study area recorded climate data (air temperature, humidity, wind speed, solar radiation) at 10 minute intervals. We used this field data as input for a spatial and temporal energy balance model of the reach. Our model demonstrates the utility of IR imagery to monitor stream temperatures and improves our understanding of energy fluxes in

  5. Water Resources and Groundwater in a Glaciated Andean Watershed (Cordillera Blanca, Peru)

    NASA Astrophysics Data System (ADS)

    McKenzie, J. M.; Gordon, R.; Baraer, M.; Lautz, L.; Mark, B. G.; Wigmore, O.; Chavez, D.; Aubry-Wake, C.

    2014-12-01

    It is estimated that almost 400 million people live in watersheds where glaciers provide at least 10% of the runoff, yet many questions remain regarding the impact of climate change and glacier recession on water resources derived from these high mountain watersheds. We present research from the Cordillera Blanca, Peru, an area with the highest density of glaciers in the tropics. While glacier meltwater buffers stream discharge throughout the range, groundwater is a major component of dry season runoff, contributing up to 50-70% of outflow in some tributaries. In order to predict future changes to water resources it is critical to understand how groundwater can offset future hydrologic stress by maintaining stream baseflow, including recharge mechanisms, subsurface pathways, storage, and net fluxes to rivers. We present a synthesis of results based on hydrologic modeling, drilling/piezometers, geophysics, and artificial and natural hydrologic tracers. Our findings show that 'pampas', low-relief mountain valleys, are critical for baseflow generation by storing groundwater on interannual timescales. Pampas have a total area of ~65 km2 and are comprised of unconsolidated glacial, talus, lacustrine and wetland (bofedales) deposits. The valleys commonly have buried talus aquifers that are overlain by low permeability, glaciolacustrine deposits. Glaciofluvial outwash deposits and small wetlands also act as unconfined aquifers. These groundwater systems appear to be primarily recharged by wet season precipitation, and at higher elevations also by glacial meltwater. Additionally a ubiquitous feature in the valleys are springs, often located at the base of talus deposits, which generate a large hydrologic flux within the hydrologic systems. While glaciers are the most visible and vulnerable component of the Andean waterscape, we argue that it is crucial to understand the complete mountain hydrologic cycle, including groundwater, in order to understand the ongoing

  6. Diagnosing the imbalance of Yanamarey Glacier in the Cordillera Blanca of Peru

    NASA Astrophysics Data System (ADS)

    Hastenrath, Stefan; Ames, Alcides

    1995-03-01

    A detailed glaciological observation program was conducted on the Yanamarey Glacier in the Cordillera Blanca of Peru, including the monitoring of net balance and ice flow velocity during 1977-1988 and mappings of the surface topography in 1973, 1982, and 1988. These observations are here evaluated to combine net balance, surface lowering, and ice flow into a consistent picture of the mode of operation of a tropical glacier on the scale of a decade. The glacier extends between 5100 and 4500 m with a total area of 9×105 m2 and length of about 1.3 km. Maximum flow velocity is 17.4 m yr-1 and maximum volume flux 336×103 m3 yr-1. In the ablation area, net balance is about -6 m yr-1 and surface lowering 3 m yr-1. About half of the mean annual water discharge from the glacier of 80 L s-1 is not renewed by precipitation but supplied by the ice thinning. The rate of surface lowering of 1.5 m yr-1 liquid water equivalent translates to a glacier average departure heat supply for melting of 16 W m-2. Sensitivity analyses indicate that this could be produced by a cloudiness increase of less than one tenth, an air temperature decrease of 2°C, an increment in specific humidity of less than 1 g kg-1, or some combination of heat budget processes. Such changes in the atmospheric environment would be required to stabilize the glacier at its recent volume. As another indication of the recent imbalance, the maximum volume flux is found some 100 m below the equilibrium line altitude. Under continuation of the recent climatic conditions, the glacier may survive for more than half a century.

  7. New measurements of particulates in glacial snow and ice in the Cordillera Blanca mountains of Peru

    NASA Astrophysics Data System (ADS)

    All, J.; Schmitt, C.; Celestian, A. J.; Rucks, M.; Arnott, W. P.; Cole, R.

    2012-12-01

    During the local dry season (June/July) of 2011 and 2012, the American Climber Science Program (organized with the assistance of the American Alpine Club) conducted scientific expeditions in Huascaran National Park in Peru. The Park is located in the Cordillera Blanca mountain range and contains the world's largest collection of tropical mountain glaciers. One component of the environmental research program was sampling particulates on glacier surfaces by means of snow collection and filtration. Over 150 samples were collected during the two expeditions by volunteer climbers working with scientists in the field. Glacier snows were collected on over fifteen peaks throughout the range at altitudes from 4800 to nearly 6800 meters. Snow samples were kept frozen until the climber-scientists returned to basecamp - at which point they were rapidly melted and then immediately filtered through 0.7 micron PallFlex tissuequartz filters. The particulates captured on the filters have been analyzed for their bulk heat absorption properties as well as to determine the properties of individual particles through X-ray diffraction for bulk mineral identification, and Raman microscopy for chemical mapping of minerals. Preliminary results indicate that snow age, altitude, as well as geographic location (with respect to urban areas, mines, and predominant wind direction) all play significant roles in the amount and types of contaminants. Multiple locations were sampled during both expeditions as well as at different times during the same climbing season. Results include the relative heating capacity of the samples at various wavelengths as well as mineral composition information across the range. Local weather patterns and geographic observations will be used to identify potential sources of contaminants. Sampling will continue under the American Climber Science Program in 2013 and beyond.

  8. Current deformation in the northern Canadian Cordillera inferred from GPS measurements

    NASA Astrophysics Data System (ADS)

    Leonard, Lucinda J.; Hyndman, Roy D.; Mazzotti, StéPhane; Nykolaishen, Lisa; Schmidt, Michael; Hippchen, Sabine

    2007-11-01

    Continuous and campaign-style Global Positioning System (GPS) measurements provide new constraints on the first-order current deformation pattern of the northern Cordillera of NW Canada and eastern Alaska. The Yakutat block is currently colliding with North America in the corner of the Gulf of Alaska. Our data infer that relative Yakutat-North America motion is accommodated across the eastern boundary by right-lateral motion (˜40 mm/a), mainly on the Fairweather fault, and minor shortening (˜6 mm/a). To the north, collision is taken up by shortening (˜31 mm/a) mainly on the Chugach-St. Elias fault system, with westward extrusion and possible counterclockwise rotation of the Yakutat block and Alaskan fore arc facilitated by ˜23 mm/a right-lateral motion that is shared by several faults. The seismicity pattern indicates that plate boundary deformation is far reaching, producing strain throughout eastern Alaska, Yukon, and western Northwest Territories. Our GPS data confirm the transfer of strain from the Yakutat collision zone and enable the extent of plate boundary deformation to be mapped, thereby defining the western edge of "stable" North America. GPS sites in SW Yukon show motion of 3-10 mm/a to the NE, confirming that strain is transferred at least 400 km from the Yakutat collision. Continued transfer north toward the Mackenzie Delta and NE to the Mackenzie Mountains, indicated by current seismicity, is not yet well resolved by the campaign GPS data, which are hampered by coseismic and postseismic effects of the 2002 Mw 7.9 earthquake on the Denali fault in eastern Alaska.

  9. New method for assessing the potential hazardousness of glacial lakes in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Emmer, A.; Vilímek, V.

    2014-02-01

    This paper presents a new and easily repeatable objective method for assessing the potential hazardousness of glacial lakes within the Peruvian region of Cordillera Blanca (excluding ice-dammed lakes, which do not reach significant volumes in this region). The presented method was designed to meet four basic principles, which we considered as being crucial. These are: (a) principle of regional focus; (b) principle of objectivity; (c) principle of repeatability; and (d) principle of multiple results. Potential hazardousness is assessed based on a combination of decision trees for clarity and numerical calculation for objectivity. A total of seventeen assessed characteristics are used, of which seven have yet to be used in this context before. Also, several ratios and calculations are defined for the first time. We assume that it is not relevant to represent the overall potential hazardousness of a particular lake by one result (number), thus the potential hazardousness is described in the presented method by five separate results (representing five different glacial lake outburst flood scenarios). These are potentials for: (a) dam overtopping resulting from a dynamic slope movement into the lake; (b) dam overtopping following the flood wave originating in a lake situated upstream; (c) dam failure resulting from a dynamic slope movement into the lake; (d) dam failure following the flood wave originating in a lake situated upstream; and (e) dam failure following a heavy earthquake. All of these potentials theoretically range from 0 to 1. The presented method was verified on the basis of assessing the pre-flood conditions of seven lakes which have produced ten glacial lake outburst floods in the past and ten lakes which have not. A comparison of these results showed that the presented method successfully identifies the potentially hazardous lakes.

  10. Fluid flow along North American Cordillera detachments determined from stable isotope and high resolution chemical analyses

    NASA Astrophysics Data System (ADS)

    Quilichini, A.; Teyssier, C.; Mulch, A.; Nachlas, W.

    2009-12-01

    Fluid flow is likely a major parameter controlling the dynamics of extensional detachment zones. Buoyancy-driven fluid flow is generated by high heat flow beneath the detachment zone, where heat is advected by crustal thinning and magma intrusions. This hydrothermal convective flow is focused in the detachment zone for the duration of activity of the detachment at relatively high temperature (300-500°C), resulting in very significant fluid-rock interaction and isotopic exchange. Quantifying sources and fluid flux in detachments is a challenge because permeability of ductilely deforming rocks is poorly understood. In order to solve these problems, we studied two different Eocene extensional systems in the North American Cordillera: the quartzitic detachment which borders the Kettle dome metamorphic core complex (WA), and the quartzo-feldspathic Bitterroot shear zone along the Idaho batholith (MT). The Kettle Dome detachment provides a continuous section of ~200 m thick quartzite mylonite where high-resolution sampling (~5 m) indicates that Deuterium isotopic ratios that are obtained from synkinematic muscovite grains are consistent with a meteoric fluid source (-130 per mil). In the Bitterroot shear zone, Coyner (2003) reported similar Deuterium isotopic ratios (down to -140 per mil) in muscovite from mylonites and ultramylonites. Microprobe analyses were obtained for white mica porphyroclasts by performing transects perpendicular to the basal (001) cleavage in order to determine intragrain chemical zoning. Preliminary results for the Kettle dome indicate increasing phengite composition with depth, suggesting enhanced activity of the Tschermak exchange. The variations of the phengitic signature in muscovite indicates that temperature diminuish downsection, which is contradictory with the results obtained by the Qz-Ms oxygen isotope thermometer along the Kettle section. Our recent work provides geologic data for numerical models that address the permeability of

  11. Recent evolution and mass balance of Cordón Martial glaciers, Cordillera Fueguina Oriental

    NASA Astrophysics Data System (ADS)

    Strelin, Jorge; Iturraspe, Rodolfo

    2007-10-01

    Past and present glacier changes have been studied at Cordón Martial, Cordillera Fueguina Oriental, Tierra del Fuego, providing novel data for the Holocene deglaciation history of southern South America and extrapolating as well its future behavior based on predicted climatic changes. Regional geomorphologic and stratigraphic correlations indicate that the last glacier advance deposited the ice-proximal ("internal") moraines of Cordón Martial, around 330 14C yr BP, during the Late Little Ice Age (LLIA). Since then glaciers have receded slowly, until 60 years ago, when major glacier retreat started. There is a good correspondence for the past 100 years between the surface area variation of four small cirque glaciers at Cordón Martial and the annual temperature and precipitation data of Ushuaia. Between 1984 and 1998, Martial Este Glacier lost 0.64 ± 0.02 × 10 6 m 3 of ice mass (0.59 ± 0.02 × 10 6 m 3 w.e.), corresponding to an average ice thinning of 7.0 ± 0.2 m (6.4 ± 0.2 m w.e), according to repeated topographic mapping. More detailed climatic data have been obtained since 1998 at the Martial Este Glacier, including air temperature, humidity and solar radiation. These records, together with the monthly mass balance measured since March 2000, document the annual response of the Martial Este Glacier to the climate variation. Mass balances during hydrological years were positive in 2000, negative in 2001 and near equilibrium in 2002. Finally, using these data and the regional temperature trend projections, modeled for different future scenarios by the Atmosphere-Ocean Model (GISS-NASA/GSFC), potential climatic-change effects on this mountain glacier were extrapolated. The analysis shows that only the Martial Este Glacier may survive this century.

  12. Strain Localization near the Brittle-Ductile-Transition along the Cordillera Blanca Shear Zone, Peru

    NASA Astrophysics Data System (ADS)

    Hughes, C. A.; Jessup, M. J.; Shaw, C. A.

    2016-12-01

    We present a case study of strain localization near the brittle-ductile-transition (BDT) from the Cordillera Blanca Shear Zone (CBSZ), Peru, a `natural laboratory' that preserves a record of changing differential stress, temperature, and deformation mechanisms associated with exhumation along a low-angle normal detachment fault in an active extensional setting. The CBSZ accommodates deformation associated with exhumation of a granodiorite batholith across the BDT along an active, 200 km long, WSW dipping low-angle normal detachment fault situated above the Peruvian flat-slab segment of the Andean margin. In the footwall, magmatic fabrics become increasingly overprinted by solid-state fabrics. An overall trend of increasing degrees of mylonitization and grain size reduction occurs from the undeformed batholith towards the detachment fault. Outstanding exposure of the shear zone in conjunction with its young age and well-constrained tectonic setting make the CBSZ an excellent venue for applying paleopiezometry and thermometry tools to link natural deformation with experimental studies. We characterize deformation associated with strain localization using quartz recrystallized grain size paleopiezometry and crystallographic preferred orientations derived from electron backscatter diffraction (EBSD) analyses in conjunction with microstructural analysis and two-feldspar thermometry. Quartz slip systems, differential stress estimates, and deformation temperatures from three transects spanning 50 km of the 200 km long shear zone are compared. Crystallographic slip systems range from dominant prism slip at positions away from the detachment to dominant basal slip nearest the detachment, with intermediate positions involving variable components of prism , rhomb , and basal slip, though not all slip systems are observed in each transect. Linked paleostress and temperature estimates allow for first-order approximations of a crustal strength profile for the CBSZ. Collectively

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

    USGS Publications Warehouse

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

    1979-01-01

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

  14. Cretaceous exhumation history of Cordillera Darwin, southern Patagonia, from patchily recrystallized garnet and U-Th-Pb monazite dating

    NASA Astrophysics Data System (ADS)

    Maloney, K. T.; Clarke, G. L.; Klepeis, K. A.; Fanning, C. M.; Wang, W.

    2010-12-01

    Garnet in amphibolite facies pelitic schists from Bahía Pia of Cordillera Darwin displays patchy textures whereby a single grain may have regions of turbid garnet with comparatively large inclusions of biotite, muscovite, plagioclase and quartz, juxtaposed against a region of clear, “ordinary” garnet. Clear areas with S1 inclusion trails are grossular rich, whereas post-S1 turbid areas are comparatively spessartine-pyrope rich. Raman spectroscopy identified the presence of an aqueous solution in turbid regions of garnet, lacking from clear areas. Turbid patches are associated with the growth of S2 kyanite and staurolite. Pseudosection modelling in Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O-TiO2-Fe2O3 (NCKFMASHTO) is consistent with garnet mode decreasing from c. 5% to less than 1% during exhumation of Cordillera Darwin, coinciding with the growth of S2 kyanite and staurolite at P≈9 kbar and T≈625°C. Turbid garnet in patchy and atoll-style textures is inferred to reflect recrystallization facilitated by fluid ingress whereby garnet cores, formed at higher P-T conditions than the rims, were preferentially recrystallised along grain cracks and boundaries. P-T paths inferred from the modelling indicate higher metamorphic conditions than previously documented, P conditions declining from 12 to 9 kbar over T= 610 to 630°C. U-Th-Pb dating of S2 monazite indicates that rapid exhumation was underway before 72.61±1.13 Ma, reflecting a tectonic shift from burial to uplift of Cordillera Darwin between c. 86 and c. 73 Ma. Sillimanite-bearing assemblages are restricted to contact aureoles associated with the intrusion of the Late Cretaceous Beagle Suite at shallower crustal conditions.

  15. The role of inherited rifted lithospheric structure on middle Cretaceous orogeny and Tertiary-present extension, North American Cordillera

    NASA Astrophysics Data System (ADS)

    Tikoff, Basil; Kelso, Paul; Fayon, Annia; Gaschnig, Richard; Vervoort, Jeff; Stetson-Lee, Tor; Byerly, Ad

    2017-04-01

    While the Eastern North American margin exhibits evidence of the rifted margin on subsequent deformation, this record is more obscure along the western Cordilleran margin. We recently conducted paleomagnetic and geochronologic analyses along the abrupt, boundary between cratonic North American and accreted terranes in Idaho. In this location, the abrupt boundary is designated by geochemical gradients (Sr, Nd, O) that are spatially coincident with major, regional-scale (western Idaho, Ahsahka) shear zones. The boundary is oriented NS in central-southern Idaho, and then abruptly changes 90° near Orofino, ID, to become EW oriented. Recent paleomagnetic data indicates that 30° clockwise rotation of the entire margin occurred post 85 Ma. Reconstruction of this rotation orients the margins at 060 (transform) and 330 (extensional), parallel to the inferred orientation of the Precambrian rifted margin elsewhere in the US Cordillera. The geometry would cause a structural syntaxis during northward (right-lateral) translation of accreted terranes. Northward terrane motion at 100 Ma result in dextral transpressional kinematics along the 330-oriented western Idaho shear zone and contractional deformation in the EW-oriented Ahsahka shear zone (Cretaceous orientations) in this syntaxis. This middle Cretaceous orogeny occurs at the other major structural syntaxis, south of the Sierra Nevada batholith in southeastern California, as a result of a 100 Ma worldwide plate re-organization. The Idaho syntaxis also acts as a fulcrum for Tertiary-present rotation, explaining the current displacement field in the northern US Cordillera. Overall, the study indicates that the inherited Precambrian rifted margin of the North American Cordillera exhibited a significant influence on subsequent deformation, despite overprinting of abundant magmatism, margin parallel terrane translation, and subsequent rotation.

  16. Glacier Inventory of the Cordillera Real - Bolivia using high resolution satellite images ALOS and CBERS-2B

    NASA Astrophysics Data System (ADS)

    Ramirez, E.; Ribeiro, R.; Machaca, A.; Fuertes, R.; Simões, J.

    2012-04-01

    The Andes represent approximately 99% of tropical glaciers worldwide. In Bolivia (South America) the glacier coverage represents 20% of the Andean glaciers. During the last 30 years a dramatic reduction of glacier surfaces in the Bolivian Andes were observed (Ramirez et al. 2001), leading to fears about the disappearance of several small glaciers in the next three decades. The first glacier inventory in this region was made based on aerial photographs for the 70's and 80's using geodetic methods (Jordan 1991). However, the realization of new photogrammetric flights over the Andes is expensive, which made it impossible to update the glacier inventory. Most Bolivian glaciers are less than 1 km2 making it difficult to use conventional satellite imagery with average resolutions (15 m or 30m). The development of new high resolution sensors mounted on observational satellites with stereoscopic capabilities permits the application of photogrammetric techniques for the precise delimitation of glacier boundaries. A new glacier inventory of the Cordillera Real in Bolivia was performed using high-resolution images (2.5 m) from ALOS (Japan) and CBERS-2B (China-Brazil) satellites within the framework of the Andean Regional Project on Climate Change Adaptation (PRAA) supported by the World Bank. The PRISM sensor of ALOS satellite (Panchromatic Remote-sensing Instrument for Stereo Mapping) and HRC of CBERS-2B satellite (High Resolution Panchromatic Camera) were used in this study. 57 ground control points (GCP) were measured along the Cordillera Real through dual-frequency DGPS's. The boundaries of 476 glaciers were identified and digitized by a digital photogrammetric station. The current glacier surface of the Cordillera Real is 185.5 km2. Compared with the previous inventory of the 80's it represent a loss of 43% of the glacier area.

  17. Lithospheric Structure Across the Cordillera-Craton Transition in NW Canada from Surface Waves Traversing the CANOE Array

    NASA Astrophysics Data System (ADS)

    Gaherty, J.; Chen, P.; Zhao, L.; Bostock, M.; Garnero, E.; Revenaugh, J.

    2006-12-01

    The Canadian Northwest Experiment (CANOE) is a nearly sixty-station broadband PASSCAL array extending from the Slave Craton in the Canadian NWT, across the Canadian Rockies in northern British Columbia and Yukon and south to Edmonton, Alberta. The array crosses a series of compressive orogens that span 4 Ga of geologic time and are undisrupted by later periods of extension or extensive volcanism, and thus provide an ideal platform for studying the growth of continental cratons through accretion. There are two competing hypothesis for the nature of the cordillera-craton transition in this region: (1) Terranes accreted in the cordillera during the Mesozoic are lithospheric-scale features. This suggests substantial growth of the North American continent since the Proterozoic, and a craton boundary near the deformation front. (2) Terranes are thin-skin thrust features overlying Proterozoic North American lithosphere. This suggests little continental growth since the Proterozoic, and a craton boundary near the Pacific coast. Surface waves traversing the CANOE array provide an excellent data set to evaluate these hypotheses. A cross-correlation procedure is used to measure the frequency-dependent travel times and amplitudes of Love and Rayleigh waveforms traversing the array. The data are derived from recordings of regional and teleseismic earthquakes recorded between June 2004 and Sept 2005. Using accurate three-dimensional sensitivity kernels for both amplitude and phase, these data are inverted for 3D tomographic images of anisotropic shear- velocities in the crust and upper-mantle across the transition from craton to cordillera. Preliminary results suggest a sharp lateral gradient in both shear velocity and shear anisotropy in the lithospheric mantle that is located very close to the current deformation front, consistent with hypothesis (1). The surface-wave observations will be integrated with receiver function and shear-wave splitting data, providing a

  18. Lithospheric Structure Across the Cordillera-Craton Transition in NW Canada from Surface Waves Traversing the CANOE Array

    NASA Astrophysics Data System (ADS)

    Gaherty, J. B.; Chen, P.; Zhao, L.; Bostock, M.; Revenaugh, J.; Garnero, E.

    2007-12-01

    The Canadian Northwest Experiment (CANOE) is a nearly sixty-station broadband PASSCAL array extending from the Slave Craton in the Canadian NWT, across the Canadian Rockies in northern British Columbia and Yukon and south to Edmonton, Alberta. The array crosses a series of compressive orogens that span 4 Ga of geologic time and are undisrupted by later periods of extension or extensive volcanism, and thus provide an ideal platform for studying the growth of continental cratons through accretion. There are two competing hypothesis for the nature of the cordillera-craton transition in this region: (1) Terranes accreted in the cordillera during the Mesozoic are lithospheric-scale features. This suggests substantial growth of the North American continent since the Proterozoic, and a craton boundary near the deformation front. (2) Terranes are thin-skin thrust features overlying Proterozoic North American lithosphere. This suggests little continental growth since the Proterozoic, and a craton boundary near the Pacific coast. Surface waves traversing the CANOE array provide an excellent data set to evaluate these hypotheses. We have developed and applied a new multi-station cross-correlation procedure to precisely measure the frequency-dependent travel times and amplitudes of Love and Rayleigh waveforms traversing the array. The data are derived from recordings of regional and teleseismic earthquakes recorded between June 2004 and Sept 2005. Using accurate three-dimensional sensitivity kernels for both amplitude and phase, these data are inverted for 3D tomographic images of anisotropic shear- velocities in the crust and upper- mantle across the transition from craton to cordillera. Preliminary results suggest a sharp lateral gradient in both shear velocity and shear anisotropy in the lithospheric mantle that is located very close to the current deformation front, consistent with hypothesis (1). The surface-wave observations will be integrated with receiver function

  19. Constraining Subsurface Structure and Composition Using Seismic Refraction Surveys of Proglacial Valleys in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Glas, R. L.; Lautz, L.; McKenzie, J. M.; Mark, B. G.; Baker, E. A.; Aubry-Wake, C.; Somers, L. D.; Wigmore, O.

    2015-12-01

    As tropical glaciers rapidly recede in response to climate change, the storage and discharge of groundwater will play an increasing role in regulating river baseflow, particularly during the dry season, when stream flow is currently sustained predominantly by glacial melt. Little is understood regarding the hydrogeologic processes controlling base flow characteristics of low-gradient proglacial valleys of the Cordillera Blanca in Northwestern Peru, which has the world's highest density of tropical glaciers. To better understand the processes of groundwater storage and discharge in proglacial meadows, we completed seismic refraction surveys in three representative valleys of the Cordillera Blanca range: the Quilcayhuanca, Yanamarey, and Pachacoto valleys. The locations of survey transects were chosen based on locations of previous sediment core sampling, GPR lines, and quantification of groundwater-surface water interaction derived from dye and temperature tracing experiments. The seismic surveys consisted of 48 vertical component geophones with 2.5 m spacing. Across the three representative valleys a total of 15 surveys were conducted, covering a distance of 1800 m in cross, down, and oblique-valley directions. Preliminary interpretation of the seismic refraction data indicates a maximum imaging depth of 16 m below land surface, and a transition from glacio-lacustrine sediments to buried saturated talus at a depth of 6 m in the Quilcayhuanca valley. The organic-rich glacio-lacustrine sediments in the Yanamarey valley have seismic velocities ranging from 300 to 800 m/s and are >16 m in thickness at mid- valley. Weathered metasedimentary bedrock in the Pachacoto valley was imaged at ~5 m below the valley surface, exhibiting a p-wave velocity of 3400 m/s. The knowledge of hydrogeologic structure derived from seismic refraction surveys will provide crucial boundary conditions for future groundwater models of the valleys of the Cordillera Blanca.

  20. Reinterpretation of the formation of the "crooked moraine" of the debris-covered Hatunraju Glacier (Cordillera Blanca, Perú)

    NASA Astrophysics Data System (ADS)

    Iturrizaga, L.

    2012-04-01

    The Hatunraju Glacier (9°00'S/70°40'W) is located in the Parón valley in the northern part of the Cordillera Blanca. The almost 4 km long and steeply inclined glacier flows down from the Huandoy-N-Side (6395 m) into the Parón valley to an elevation of 4250 m a.s.l.. The extremely narrow glacier is in its entire ablation area heavily debris-covered. It is one of the few glaciers, which dam with its debris-mantled glacier tongue a main river in this mountain range. In this case the Hatunraju glacier produces the largest glacier-dammed lake in the Cordillera Blanca, the Laguna Parón. In some other aspects, this glacier proves to be distinct from the majority of the glaciers in the Cordillera Blanca: It is flowing on an almost up to 250 m high moraine pedestal ("moraine-dammed raised bed glacier") and the glacier makes a bend of almost 90° when entering into the main valley. The present paper focuses in particular on the last point: the formation of the so called "crooked moraine". It has been explained by Lliboutry (1977) as a result of a glacier lake outburst and the subsequent destruction of the latero-frontal moraine. The later process supposed to be the trigger of the abrupt change in the flow direction of the lower part of the glacier. Recent investigations suggest an alternative genesis of the crooked moraine considering the distinct phases of the glaciation history of the Parón valley. The here proposed formation pattern is also paradigmatic for other crooked debris-covered glaciers, especially in High Asia. Comparative examples will be provided from the Karakoram and Himalayas. The research work on the Hatunraju Glacier is part of a project on the glacial geomorphology in the Tropical Andes financed by the Alexander von Humboldt-Foundation.

  1. Three-dimensional structural evolution and kinematics of the Piedemonte Llanero, Central Llanos foothills, Eastern Cordillera, Colombia

    NASA Astrophysics Data System (ADS)

    Egbue, Obi; Kellogg, James

    2012-11-01

    The Piedemonte Llanero is a wedge duplex zone in the Llanos foothills on the eastern flank of the Eastern Cordillera of Colombia. It is located northeast of the Cusiana and Cupiagua hydrocarbon fields. The area is characterized by a series of moderate to high-angle duplexes with east-southeast verging thin-skinned and thick-skinned tectonics. We present a structural model constrained by 2-D and 3-D seismic reflection data, surface geology, and well data. The structural analysis is based on backward modeling (kinematic restoration) and forward modeling using transfer-flexural slip and fault slip fold algorithms. The structures are significantly tighter in the northern segment compared to the southern segment of the overthrust trend. We estimate approximately 17 km of shortening in the northern duplex zone, and about 26 km total shortening for the southern duplex zone. We propose that thin-skinned in-sequence imbricate thrust stack deformation produced most of the shortening. The main Andean deformation (80% of the total shortening) commenced in the Piedemonte area about 6 Ma with rapid shortening and uplift in the area resulting in the development of an active-roof duplex structure as the cover was bulldozed forward by a horse block (Monterralo anticline) ramping up to a detachment at the base of C2, then ramping to the surface as the Yopal thrust. Later the horse blocks in the wedge rose, underthrusting the cover in a passive-roof duplex triangle zone. This was followed by an out-of-sequence Laramide-style thick-skinned basement-uplift of the range which produced much of the structural relief of the Eastern Cordillera. Cenozoic deformation in the Eastern Cordillera has been primarily range-normal, but has involved an increasing component of mountain-parallel right-lateral shear in the last 2 Ma.

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

    PubMed Central

    Avendaño, Jorge Enrique; Donegan, Thomas M.

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

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

    PubMed

    Avendaño, Jorge Enrique; Donegan, Thomas M

    2015-01-01

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

  5. An enigmatic frog of the genus Atelopus (Family Bufonidae) from Parque Nacional Chirripó, Cordillera de Talamanca, Costa Rica.

    PubMed

    Savage, Jay M; Bolaños, Federico

    2009-01-01

    A distinctive new species of Atelopus is described from Parque Nacional Chirrip6 Grande, Cordillera de Talamanca (3,400-3,500 m). It closely resembles populations of the Atelopus ignescens complex from the Andes of northern Ecuador and southern Colombia. It differs most significantly from these frogs in the pattern of spiculae and coni development on the throat, chest, hands and feet. The Costa Rican species appears to be an outlier of the complex inexplicably separated geographically from its nearest allies by an over land distance of about 1,600 km.

  6. Mapping Glacier Dynamics and Proglacial Wetlands with a Multispectral UAV at 5000m in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Wigmore, O.; Mark, B. G.

    2015-12-01

    The glaciers of the Cordillera Blanca, Peru are rapidly retreating as a result of rising temperatures, transforming the hydrology and impacting the socio-economic and environmental systems of the Rio Santa basin. Documenting the heterogeneous spatial patterns of these changes to understand processes of water storage and flow is hindered by technologic and logistic challenges. Highly complex topography, cloud cover and coarse spatial resolution limit the application of satellite data while airborne data collection remains costly and potentially dangerous. However, recent developments have made Unmanned Aerial Vehicle (UAV) technology a viable and potentially transformative method for studying glacier dynamics and proglacial hydrology. The extreme altitudes (4000-6700m) of the Cordillera Blanca limit the use of 'off the shelf' UAVs. Therefore we developed a low cost multispectral (visible, near-infrared and thermal infrared) multirotor UAV capable of conducting fully autonomous aerial surveys at elevations over 5000m within the glacial valleys of the Cordillera Blanca. Using this platform we have completed repeat aerial surveys (in 2014 and 2015) of the debris covered Llaca Glacier, generating highly accurate 10-20cm DEM's and 5cm orthomosaics using a structure from motion workflow. Analysis of these data reveals a highly dynamic system with some areas of the glacier losing as much as 16m of vertical elevation, while other areas have gained up to 5m of elevation over one year. The magnitude and direction of these changes appears to be associated with the presence of debris free ice faces and meltwater ponds. Additionally, we have mapped proglacial meadow and wetland systems. Thermal mosaics at 10-20cm resolution are providing novel insights into the hydrologic pathways of glacier meltwater including mapping the distribution of artesian springs that feed these wetland systems. The high spatial resolution of these UAV datasets facilitates a better understanding of the

  7. Demand for radiotherapy in Spain.

    PubMed

    Rodríguez, A; Borrás, J M; López-Torrecilla, J; Algara, M; Palacios-Eito, A; Gómez-Caamaño, A; Olay, L; Lara, P C

    2017-02-01

    Assessing the demand for radiotherapy in Spain based on existing evidence to estimate the human resources and equipment needed so that every person in Spain has access to high-quality radiotherapy when they need it. We used data from the European Cancer Observatory on the estimated incidence of cancer in Spain in 2012, along with the evidence-based indications for radiotherapy developed by the Australian CCORE project, to obtain an optimal radiotherapy utilisation proportion (OUP) for each tumour. About 50.5 % of new cancers in Spain require radiotherapy at least once over the course of the disease. Additional demand for these services comes from reradiation therapy and non-melanoma skin cancer. Approximately, 25-30 % of cancer patients with an indication for radiotherapy do not receive it due to factors that include access, patient preference, familiarity with the treatment among physicians, and especially resource shortages, all of which contribute to its underutilisation. Radiotherapy is underused in Spain. The increasing incidence of cancer expected over the next decade and the greater frequency of reradiations necessitate the incorporation of radiotherapy demand into need-based calculations for cancer services planning.

  8. A 21 ± 2 Ma age for the termination of the ductile alpine deformation in the internal zone of the betic cordilleras, South Spain

    NASA Astrophysics Data System (ADS)

    Zeck, H. P.; Albat, F.; Hansen, B. T.; Torres-Roldán, R. L.; Garciá-Casco, A.; Martín-Algarra, A.

    1989-11-01

    Rb-Sr dating of WR-muscovite pairs from two mica schists and two gneisses from the Vélez-Málaga-Torrox area, 40 km E of Málaga, gives tie lines indicating ages of 23.4 ± 2.7, 19.3 ± 2.2, 19.5 ± 0.7 and 22.4 ± 0.7 Ma, respectively. Geological evaluation suggests that these analytical ages indicate an age of 21 ± 2 (2σ) Ma for the metamorphic culmination connected with the latest phase of ductile deformation in the area. This Early Miocene (Aquitanian) age compares well with published radiometric ages for major orogenic processes in the westernmost Mediterranean and it is suggested that a significant part of the Alpine orogeny in the region took place in the restricted period of 19-23 Ma ago. Uplift rates in the order of 3-5 km/Ma are tentatively suggested.

  9. Simultaneous batholith emplacement, terrane/continent collision, and oroclinal bending in the Blue Mountains Province, North American Cordillera

    NASA Astrophysics Data System (ADS)

    Žák, Jiří; Verner, Kryštof; Tomek, Filip; Holub, František V.; Johnson, Kenneth; Schwartz, Joshua J.

    2015-06-01

    The North American Cordillera is a classic example of accretionary orogen, consisting of multiple oceanic terranes attached to the western margin of Laurentia during the Mesozoic times. Although the Cordillera is linear for most parts, terrane boundaries are at a high angle to the overall structural grain in several segments of the orogen, which has been a matter of longstanding controversy as to how and when these orogenic curvatures formed. This paper discusses mechanisms, kinematics, and timing of initiation of one of these major curvatures, the Blue Mountains Province in northeastern Oregon. Here magmatic fabric patterns and anisotropy of magnetic susceptibility in the Wallowa batholith record three phases of progressive deformation of the host Wallowa terrane during Early Cretaceous. First is terrane-oblique ~NE-SW shortening, interpreted as recording attachment of the amalgamated oceanic and fringing terranes to the continental margin during dextral convergence at ~140 Ma. Deformation subsequently switched to pure shear-dominated ~NNE-SSW shortening associated with crustal thickening, caused by continued impingement of the amalgamated Blue Mountains superterrane into a presumed westward concave reentrant in the continental margin at ~135-128 Ma. Upon impingement (at ~126 Ma), the northern portion of the superterrane became "locked," leading to reorientation of the principal shortening direction to ~NNW-SSE while its still deformable southern portion rotated clockwise about a vertical axis. We thus propose oblique bending as the main mechanism of the orocline formation whereby horizontal compressive forces resulting from plate convergence acted at an angle to the terrane boundaries.

  10. Structure of the Cordillera de la Costa Belt, North-Central Venezuela: Implications for plate tectronic models

    SciTech Connect

    Ave Lallemant, H.G.; Sisson, V.B.; Wright, J.E. )

    1993-02-01

    Preliminary results of an on-going study of the Cordillera de la Costa belt between Puerto Cabello and Choroni, north-central Venezuela, indicate that the deformational history is far more complicated than expected from simple plate-tectonic models. The Cordillera de la Costa belt consists of oceanic rocks (e.g., serpentinites, amphibilites, with lenses of eclogite and blueschist) intimately intermixed with metamorphosed continental margin deposits (e.g., mica and graphite schist, quartzite, marble). Locally, large granitic (basement ) complexes of Lower Paleozoic age are included as well. In late Cretaceous time, the entire belt was involved in four synmetamorphic deformations phases (D[sub 1a] to D[sub 1d]); the first (D[sub 1a]) occurred at depths of at 35-40 km and the later ones at successively shallower depths. This deformation occurred in a subduction zone, related to right-oblique convergence of the Farallon and Atlantic plates. The most penetrative structures resulted from (all in present coordinates) north-south contraction and east-west dextral simple shear (D[sub 1b]). During an Early Tertiary ( ) event (D[sub 2]), the belt was emplaced southward onto the South American continental margin. Subsequent deformational structures (D[sub 3]) resulted in cross folds and faults (with small pull-apart basins) which are consistent with the eastward passage of the Caribbean past the South American plate.

  11. Volcanism subprogram: Volcanological interpretation of the northern part of the Occidental Cordillera of Bolivia, utilizing ERTS imagery

    NASA Technical Reports Server (NTRS)

    Brockmann, C. E. (Principal Investigator); Kussmaul, S.

    1973-01-01

    The author has identified the following significant results. In the present study, 6 ERTS-1 images have been interpreted on a 1:1 million scale (black and white) with the respective field reconnaissance. The area studied is located in the region bordering with Chile and includes the western part of the Bolivian Altiplano, the volcano Cordillera (western cordillera) and the northern part of Chile to the Pacific Coast. The greater part of this region is formed by Pliocene/Pleistocene volcani rock, which is discordant with the Tertiary sediments with intercalations of calcareous tuff. The ERTS-1 imagery permits the tracing of regional boundaries of the great volcanic formations and the alinements of the volcanic bodies along the fault zones. They also permit a clear examination of the volcanic apparatus, including their secondary forms, such as lava flows, parasitic cones, and lava domes. Because of the great scale, it is not possible to identify either the small structures or those of low relief. On the basis of the interpretation of the images, it is possible to give an idea of the relative age of the volcanoes.

  12. Balanced cross section, kinematic deformation model, and palinspastic facies analysis for the Bogota fold belt, Eastern Cordillera, Colombia

    SciTech Connect

    Villamil, T. ); Restrepo, P. ); Ratliff, R.; Wu, S.; Kligfield, R.; Geiser, P. )

    1993-02-01

    The Bogota fold belt of the Eastern Cordillera, Colombia has long been considered a relatively simple zone of Tertiary-aged folding. To a large degree this picture is due to the presence of a monotonous sequence of turbidites which containes very few distinct formation boundaries useful for delineating the structural geometry. However, new surface mapping together with biostratigraphic and sequence stratigraphic zonation have been used to define a complex thrust system involving southeast vergent imbricate and duplex structures. Biozone and facies boundaries are recognizable throughout the mapped area and provide a high resolution stratigraphic template for structural analysis. The thrustbell architecture is illustrated by a 17 km long balanced cross section which has been constructed using kinematic fault bend and fault propagation fold models. The use of balanced section construction techniques has in turn allowed further refinement of the stratigraphic model and facies analysis in the palinspastic restoration. The cross section constrains an overall breakforward sequence of thrust initiation with a lower detachment in shales at the base of the Cretaceous Caqueza Group. There are a minimum of 16 major ramps through the Cretaceous section and an irregularly developed upper detachment near the top of the Caqueza Group. The deformation has resulted in a minimum of 13 km of horizontal shortening in this portion of the Eastern Cordillera.

  13. Recent trends in annual snowline variations in the northern wet outer tropics: case studies from southern Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Veettil, Bijeesh Kozhikkodan; Wang, Shanshan; Bremer, Ulisses Franz; de Souza, Sergio Florêncio; Simões, Jefferson Cardia

    2017-07-01

    This paper describes the changes in the annual maximum snowlines of a selected set of mountain glaciers at the southern end of the Cordillera Blanca between 1984 and 2015 using satellite images. Furthermore, we analysed the existing glacier records in the Cordillera Blanca since the last glacial maximum to understand the evolution of glaciers in this region over a few centuries. There was a rise in the snowline altitude of glaciers in this region since the late 1990s with a few small glacier advances. Historical to the present El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) records were also analysed to understand whether there was a teleconnection between the glacier fluctuations in the region and the phase changes of ENSO and PDO. We also assessed the variations in three important climatic parameters that influence the glacier retreat—temperature, precipitation, and relative humidity—over a few decades. We calculated the anomalies as well as the seasonal changes in these variables since the mid-twentieth century. There was an increase in temperature during this period, and the decrease in precipitation was not so prominent compared with the temperature rise. There was an exceptionally higher increase in relative humidity since the early 2000s, which is relatively higher than that expected due to the observed rate of warming, and this increase in humidity is believed to be the reason behind the unprecedented rise in the snowline altitudes since the beginning of the twenty-first century.

  14. Role of plate kinematics and plate-slip-vector partitioning in continental magmatic arcs: Evidence from the Cordillera Blanca, Peru

    SciTech Connect

    McNulty, B.A.; Farber, D.L.; Wallace, G.S.; Lopez, R.; Palacios, O.

    1998-09-01

    New structural and geochronological data from the Cordillera Blanca batholith in the Peruvian Andes, coupled with Nazca-South American plate-slip-vector data, indicate that oblique convergence and associated strike-slip partitioning strongly influenced continental magmatic arc evolution. Both the strain field and mode of magmatism (plutonism vs. volcanism) in the late Miocene Peruvian Andes were controlled by the degree to which the arc-parallel component of the plate slip vector was partitioned into the arc. Strong strike-slip partitioning at ca. 8 Ma produced arc-parallel sinistral shear, strike-slip intercordilleran basins and east-west-oriented tension fractures that facilitated emplacement of the Cordillera Blanca batholith (ca. 8.2 {+-} 0.2 Ma). Periods during which the strike-slip component was not partitioned into the arc (ca. 10 and ca. 7 Ma) were associated with roughly arc-normal contraction and ignimbrite volcanism. The data thus support the contention that contraction within continental magmatic arcs favors volcanism, whereas transcurrent shear favors plutonism. The tie between oblique convergence and batholith emplacement in late Miocene Peruvian Andes provides a modern analogue for batholiths emplaced as the result of transcurrent shear in ancient arcs.

  15. A new species of semiarboreal toad of the Rhinella festae group (Anura, Bufonidae) from the Cordillera Azul National Park, Peru

    PubMed Central

    Cusi, Juan C.; Moravec, Jiří; Lehr, Edgar; Gvoždík, Václav

    2017-01-01

    Abstract A new semiarboreal species of the Rhinella festae group is described from montane forests of the Cordillera Azul National Park between 1245 and 1280 m a.s.l. in the Cordillera Oriental, San Martín region, northern Peru. The new species is morphologically and genetically compared with members of the Rhinella acrolopha group (former genus Rhamphophryne) and members of the R. festae group. The new species is characterized by its large size (female SVL 47.1–58.3 mm, n = 4), eight presacral vertebrae, fusion of the sacrum and coccyx, long protuberant snout, snout directed slightly anteroventral in lateral view, cranial crests moderately developed, absence of occipital crest, presence of tympanic membrane, dorsolateral rows of small conical tubercles extending from parotoid gland to groin, hands and feet with long digits, fingers basally webbed and toes moderately webbed. Phylogenetically it is a member of the R. festae group which is most closely related to R. chavin and R. yanachaga from Peru. Morphologically the new species shares similarities with R. tenrec and R. truebae, members of the R. acrolopha group from Colombia. PMID:28769671

  16. A new species of semiarboreal toad of the Rhinella festae group (Anura, Bufonidae) from the Cordillera Azul National Park, Peru.

    PubMed

    Cusi, Juan C; Moravec, Jiří; Lehr, Edgar; Gvoždík, Václav

    2017-01-01

    A new semiarboreal species of the Rhinella festae group is described from montane forests of the Cordillera Azul National Park between 1245 and 1280 m a.s.l. in the Cordillera Oriental, San Martín region, northern Peru. The new species is morphologically and genetically compared with members of the Rhinella acrolopha group (former genus Rhamphophryne) and members of the R. festae group. The new species is characterized by its large size (female SVL 47.1-58.3 mm, n = 4), eight presacral vertebrae, fusion of the sacrum and coccyx, long protuberant snout, snout directed slightly anteroventral in lateral view, cranial crests moderately developed, absence of occipital crest, presence of tympanic membrane, dorsolateral rows of small conical tubercles extending from parotoid gland to groin, hands and feet with long digits, fingers basally webbed and toes moderately webbed. Phylogenetically it is a member of the R. festae group which is most closely related to R. chavin and R. yanachaga from Peru. Morphologically the new species shares similarities with R. tenrec and R. truebae, members of the R. acrolopha group from Colombia.

  17. Tectonic and unroofing history of Neogene Manantiales foreland basin deposits, Cordillera Frontal (32°30'S), San Juan Province, Argentina

    NASA Astrophysics Data System (ADS)

    Pérez, Daniel J.

    2001-12-01

    The Miocene Manantiales foreland basin is located in Cordillera Frontal of San Juan, between 32°30' and 33°S. The unroofing study of the synorogenic Miocene deposits provides information about the structural evolution of Cordón de La Ramada fold-and-thrust belt. These Tertiary deposits are represented by the Chinches Formation and comprise seven members (Tc0-Tc6). They are the result of the uplift of Mesozoic sequences that crop out in La Ramada fold-and-thrust belt of the Cordillera Principal. Quaternary deposits unconformably overlying the Chinches Formation are composed of granitic and rhyolitic blocks, and represent the final uplift of the Cordón del Espinacito and a series of out-of-sequence thrusts. The unroofing studies also provide sufficient information to establish the out-of-sequence timing of the deformation at this latitude. Initial deposition of the Tertiary deposits can be dated at about 20 Ma, or early Miocene. Andesitic lavas dated in 9.2±0.3, 10.7±0.7, and 12.7±0.7 Ma unconformably overlie the structure of La Ramada fold-and-thrust belt. These facts constrain the uplift of the High Andes between 20 and 10 Ma at this latitude. The unconformity between Tertiary and Quaternary deposits suggests final uplift during Pliocene-Pleistocene times.

  18. Light pollution in Spain 2010

    NASA Astrophysics Data System (ADS)

    Sánchez de Miguel, A.; Zamorano, J.; Pila-Díez, B.; Rubio, J.; Ruiz, R.; Rodríguez-Herranz, I.; González-Pérez, A.

    2011-11-01

    The most recent data on electricity consumption for public lighting inSpain is presented and compar