19 research outputs found

    Late-Variscan multistage hydrothermal processes unveiled by chemical ages coupled with compositional and textural uraninite variations in W-Au deposits in the western Spanish Central System Batholith

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    The scheelite skarn from Los Santos and the W-Au veins from El Cabaco district, located in the Spanish Central System Batholith (SCSB), are some of the best-known tungsten ore deposits in Spain. Uraninite is an accessory mineral in both deposits, which underwent several hydrothermal flow events. Chemical and textural characteristics, as well as electron microprobe U-Th-Pb uraninite chemical data from the different stages of the skarn and the vein-type mineralizations, are presented here. Based on these data the uraninite was able to be classified into two groups. Group I uraninite has an octahedral habit and occurs as inclusions in K-feldspar relicts of the leucogranite related to Los Santos skarn formation. It shows high Th (6.95 to 8.51wt.% ThO2) and high Rare Earth Elements (REEs) contents (0.55 to 1.38wt.% ∑REE2O3). Group II uraninite occurs i) associated to El Cabaco granite, in a greenish selvage-style greisen and its reddish envelope and in the mineralized rimming quartz veins and ii) in Los Santos high-temperature endoskarn and anorthite skarn, where it is associated with U-rich mica. This uraninite type has lower Th and ∑REE2O3contents than Group-I uraninite. The mineral chemistry and the assemblage and textural relationships suggest that Group-I uraninite is magmatic and the attained U-Th-Pb chemical age of 300±4Ma is interpreted as the magmatic age of the skarn-forming aplite granites in the western part of the SCSB. Group-II uraninite includes two events: i) hydrothermal uraninite, which yields an age of 295±2Ma, dates a strong alkali mobilization and early tungsten deposition and ii) a later hydrothermal process, around 287±4Ma, that resulted in sulfides and late scheelite precipitation and widespread silicification. Finally, the gold deposition is younger than this silicification according to textural criteria. Therefore, W-Au deposits in the western part of the SCSB were formed by superposition of several processes that took place some 15Ma after the skarn-forming granite crystallized. Comparable W, W-Au and U deposits in the Variscan orogenic belt show a similar timing of hydrothermal events, suggesting that the hydrothermal history was controlled by large-scale Late-Variscan tectonic processes

    Interacción entre cuencas sedimentarias intra-continentales y volcanismo monogenético de pequeño volumen: Cuencas de Argamasilla y Calzada-Moral - Región Volcánica del Campo de Calatrava, España

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    We study the volcaniclastic lithofacies interbedded between siliciclastic and carbonate sediments of Cenozoic-Quaternary age (8.7 Ma to 7,000 BP) in Argamasilla and Calzada-Moral basins (Central Spain). The siliciclastic and carbonate deposits correspond to fluvio-lacustrine sedimentary environments. The volcanic materials consist of primary and reworked volcaniclastic successions sourced from the Campo de Calatrava Volcanic Field. Pyroclastic deposits are related to monogenetic and small-volume volcanic centres, such as scoria cones, tuff rings and maars, corresponding to Strombolian and phreatomagmatic eruptive styles. Taking into account sedimentological constraints seven volcaniclastic lithofacies were distinguished. Type A corresponds to subaerial pyroclastic fall deposits, as is inferred by the common disorganization of the deposit, their breccia-like aspect with presence of large bombs, poor sorting and lack of tractional sedimentary structures. Types B1, B2, B3 and B4 have different volcanic sources and are interpreted to be the product of low-density (dilute) pyroclastic surges, with textural features indicative of fluctuations in flow regime. This interpretation is based on the fabric and grain size of pyroclasts, together with the size and geometry of the internal sedimentary structures. Type C represents a secondary volcanic deposit related to volcanic sediments reworked by transitional hyperconcentrated flows and dilute fluvial processes, having subsequently accumulated in braided fluvial systems. Finally, the Type D is interpreted as an intra-maar scoria/spatter cones related to the development of maars. The most important factors that determined the sedimentation in these basins were orientation of basement faults, paleogeographic and sedimentological controls, style of eruption and volcaniclastic lithofacies type.Cenozoica y Cuaternaria (8,7 Ma a 7.000 BP) en las cuencas de Argamasilla y de Calzada-Moral (centro de España). Los depósitos carbonatados y siliciclásticos corresponden a ambientes sedimentarios fluvio-lacustres. Los materiales volcánicos se componen de sucesiones primarias y retrabajadas originadas en el Campo Volcánico del Campo de Calatrava. Los depósitos piroclásticos están relacionados con centros volcánicos monogenéticos y de pequeño volumen, como conos de escoria, anillos de tobas y maars, correspondientes a erupciones estrombolianas y freatomagmáticas. Teniendo en cuenta el análisis sedimentológico se han distinguido siete litofacies volcanoclásticas. El Tipo A corresponde a depósitos de caída piroclástica subaérea, como se infiere por la desorganización común del depósito, su aspecto de breccia con presencia de grandes bombas, mala clasificación y la ausencia de estructuras sedimentarias de tracción. Los tipos B1, B2, B3 y B4 tienen diferentes fuentes volcánicas y se interpretan como productos de oleadas piroclásticas de baja densidad (diluidas), con características texturales indicativas de las fluctuaciones del régimen de flujo. Esta interpretación se basa en el tamaño de grano de los piroclastos, y el tamaño y la geometría de las estructuras sedimentarias internas. El Tipo C representa un depósito volcánico secundario relacionado con sedimentos volcánicos retrabajados por flujos hiperconcentrados de transición y procesos fluviales diluidos, habiéndose acumulado posteriormente en sistemas fluviales trenzados. Por último, el Tipo D se interpreta como un cono de escoria/salpicaduras intra-maar relacionado con el desarrollo de un maar. Los principales factores que determinaron la sedimentación en estas cuencas fueron la orientación de las fallas del basamento, los controles sedimentológicos y paleogeográficos, así como el estilo eruptivo y el tipo de litofacies volcanoclástica

    Textural and mineral-chemistry constraints on columbite group minerals in the Penouta deposit: evidence from magmatic and fluid-related processes.

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    The Penouta Sn-Ta deposit, in the northwest of Spain, is a greisenized granitic cupola where Ta minerals occur mainly as disseminations in a leucogranite body intruded in Precambrian-Lower Cambrian gneises and mica-schists. This leucogranite is a medium- to fine-grained inequigranular rock consisting mainly of quartz, albite, K-feldspar and muscovite. Accessory minerals are mainly of spessartine, zircon, cassiterite, Nb-Ta oxides, monazite, xenotime, native bismuth and pyrite. The alteration processes were mainly albitization, muscovitization and kaolinitization. This leucogranite is peraluminous and P-poor, with 0.03-0.07 wt.% P2O5, 900-1500 ppm Rb, 30-65 ppm Cs, 120-533 ppm Li, 80-140 ppm Ta, 51-81 ppm Nb and up to 569 ppm of Sn. Mineralogical characterization of Nb-Ta oxide minerals was determined by X-ray diffraction, scanning electron microscopy, electron microprobe analysis and mineral liberation analysis. Mn-rich members of the columbite-group minerals (CGM) are the most common Ta-bearing phases, but microlite, wodginite, tapiolite and Ta-rich cassiterite occur also. CGM crystals are commonly zoned concentrically, with a Nb-rich core surrounded by a Ta-rich rim, with a sharp boundary between them. Convoluted zoning occurs also. Dissolution textures resulting from the corrosion of columbite and tantalite rims, in particular, are common. TheMn/(Mn + Fe) ratio varies between 0.33 and 0.97 and the Ta/(Ta + Nb) ratio between 0.07 and 0.93. Wodginite and microlite formed as late replacements of CGM and occur associated with tantalite and cassiterite. Subhedral to anhedral cassiterite crystals, usually up to 200 μmacross, occur in two generations: the earlier one is Nb,Ta-poor whereas in the later generation, the Ta content can reach >9 wt.%of Ta2O5 and 1.7 wt.%of Nb. The presence of a fluid phase in the apical zone of the granite, probably related to the separation of a fluid/vapour of the melt, could explain the sponge-like textures, the Ta enrichment associated with these textures, the occurrence of Taenriched mineral phases (microlite and wodginite) and their common interstitial character

    Controle alternativo de podridões pós‑colheita de framboesas

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    O objetivo deste trabalho foi avaliar o efeito de tratamentos pré-colheita sobre a ocorrência de podridões pós-colheita e sobre os atributos de qualidade de framboesas (Rubus idaeus L.) 'Heritage'. As frutas foram pulverizadas com um dos seguintes tratamentos: água destilada (controle), 6 g L-1 de quitosana, 100 mg L-1 de dióxido de cloro, Bacillus amyloliquefaciens, Curtobacterium pusillum ou Saccharomyces cerevisiae. Foram realizadas colheitas aos 3, 7 e 14 dias após a aplicação dos tratamentos. Após cada uma das colheitas, realizadas no estádio de maturação comercial (coloração rosa), as frutas foram inoculadas individualmente com suspensão de conídios (2x10(5) conídios mL-1) de Botrytis cinerea ou Rhizopus stolonifer. As frutas foram mantidas a 12±0,5ºC por sete dias e avaliadas quanto à incidência de podridões e quanto aos principais atributos de qualidade. Bacillus amyloliquefaciens, C. pusillum e S. cerevisiae proporcionaram menor área abaixo da curva de progresso da incidência das podridões por Botrytis e Rhizopus. Os agentes de controle biológico avaliados não interferem negativamente sobre os atributos de qualidade das frutas, e, portanto, são alternativas potenciais no controle de podridões pós-colheita de framboesas

    Atlas de las praderas marinas de España

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    Knowledge of the distribution and extent of seagrass habitats is currently the basis of management and conservation policies of the coastal zones in most European countries. This basic information is being requested through European directives for the establishment of monitoring programmes and the implementation of specific actions to preserve the marine environment. In addition, this information is crucial for the quantification of the ecological importance usually attributed to seagrass habitats due to, for instance, their involvement in biogeochemical cycles, marine biodiversity and quality of coastal waters or global carbon budgets. The seagrass atlas of Spain represents a huge collective effort performed by 84 authors across 30 Spanish institutions largely involved in the scientific research, management and conservation of seagrass habitats during the last three decades. They have contributed to the availability of the most precise and realistic seagrass maps for each region of the Spanish coast which have been integrated in a GIS to obtain the distribution and area of each seagrass species. Most of this information has independently originated at a regional level by regional governments, universities and public research organisations, which explain the elevated heterogeneity in criteria, scales, methods and objectives of the available information. On this basis, seagrass habitats in Spain occupy a total surface of 1,541,63 km2, 89% of which is concentrated in the Mediterranean regions; the rest is present in sheltered estuarine areas of the Atlantic peninsular regions and in the open coastal waters of the Canary Islands, which represents 50% of the Atlantic meadows. Of this surface, 71.5% corresponds to Posidonia oceanica, 19.5% to Cymodocea nodosa, 3.1% to Zostera noltii (=Nanozostera noltii), 0.3% to Zostera marina and 1.2% to Halophila decipiens. Species distribution maps are presented (including Ruppia spp.), together with maps of the main impacts and pressures that has affected or threatened their conservation status, as well as the management tools established for their protection and conservation. Despite this considerable effort, and the fact that Spain has mapped wide shelf areas, the information available is still incomplete and with weak precision in many regions, which will require an investment of major effort in the near future to complete the whole picture and respond to demands of EU directives

    Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

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    BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

    Atlas de las praderas marinas de España

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    Knowledge of the distribution and extent of seagrass habitats is currently the basis of management and conservation policies of the coastal zones in most European countries. This basic information is being requested through European directives for the establishment of monitoring programmes and the implementation of specific actions to preserve the marine environment. In addition, this information is crucial for the quantification of the ecological importance usually attributed to seagrass habitats due to, for instance, their involvement in biogeochemical cycles, marine biodiversity and quality of coastal waters or global carbon budgets. The seagrass atlas of Spain represents a huge collective effort performed by 84 authors across 30 Spanish institutions largely involved in the scientific research, management and conservation of seagrass habitats during the last three decades. They have contributed to the availability of the most precise and realistic seagrass maps for each region of the Spanish coast which have been integrated in a GIS to obtain the distribution and area of each seagrass species. Most of this information has independently originated at a regional level by regional governments, universities and public research organisations, which explain the elevated heterogeneity in criteria, scales, methods and objectives of the available information. On this basis, seagrass habitats in Spain occupy a total surface of 1,541,63 km2, 89% of which is concentrated in the Mediterranean regions; the rest is present in sheltered estuarine areas of the Atlantic peninsular regions and in the open coastal waters of the Canary Islands, which represents 50% of the Atlantic meadows. Of this surface, 71.5% corresponds to Posidonia oceanica, 19.5% to Cymodocea nodosa, 3.1% to Zostera noltii (=Nanozostera noltii), 0.3% to Zostera marina and 1.2% to Halophila decipiens. Species distribution maps are presented (including Ruppia spp.), together with maps of the main impacts and pressures that has affected or threatened their conservation status, as well as the management tools established for their protection and conservation. Despite this considerable effort, and the fact that Spain has mapped wide shelf areas, the information available is still incomplete and with weak precision in many regions, which will require an investment of major effort in the near future to complete the whole picture and respond to demands of EU directives.Versión del edito

    Overview of the JET results in support to ITER

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    Zircon and allanite U-Pb ID-TIMS ages of vaugnerites from the Calzadilla pluton, Salamanca (Spain): dating mantle-derived magmatism and post-magmatic subsolidus overprint.

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    Basic to intermediate high-K, high-Mg mantle-derived rocks occur throughout the Iberian Massif and are particularly important in the Tormes Dome, where vaugnerites form several stocks and small plutons. One of the largest and geochemically most variable among these plutons is the Calzadilla pluton in the Tormes Dome that crystallized at 318 ± 1.4Ma (Bashkirian; U-Pb TIMS zircon). This age reveals that the vaugnerite pluton was emplaced during the transition from late D2 extensional deformation to early D3 contractional deformation (319 to 317Ma). Large-scale extension in the area resulted, on one hand, in extensive anatexis in the crust due to quasiisothermal decompression and mica-dehydration melting and, on the other hand, in the upwelling of the mantle, which induced partial melting of the enriched domains in the lithospheric mantle. The driving reason why crustal and mantle melts were coeval is extension. The U-Pb ID-TIMS age of allanite is not related to the emplacement nor cooling of the Calzadilla vaugnerite, but it seems to be related to a younger subsolidus overprint ca. 275Ma that, in the scale of the Central Iberian Zone, corresponds to a period of hydrothermal alteration, including episyenite formation and tungsten mineralization
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