34 research outputs found

    Multiproxy characterization of high energy layers in the nner continental shelf of Quarteira (Southern Portugal) - Preliminary results

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    The occurrence of sedimentary layers indicating high energy events is common in the continental shelves sedimentary record. Their presence has been usually related either to tsunami waves or storm waves. In both cases, the identification of the transport mechanism requires a variety of proxies. This work presents the preliminary results of the analysis of a gravity core (MW-107) collected at ca. 57 m water depth in the inner continental shelf of Quarteira (Algarve) and aims to identify potential high energy events.IPMA-2020-011-BIinfo:eu-repo/semantics/publishedVersio

    Chemical factors controlling the steady-state distribution of mixed carbonate-siliciclastic sediments in Bayona Bay (northwest Spain)

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    The relative space distributions of single mineral constituents in mixed terrigenous-carbonated sediments of the Bayona Bay have been analysed. In order to determine the existence of different mixing mechanisms, a study comparing the general sedimentary trends resulting from the average patterns and the single mineral behaviour, reflected in the single-mineral mapping, was carried out. The relative abundance of all mineral phases in surface sediment samples was first determined by quantitative X-ray powder diffraction data, using the Rietveld method. This procedure enabled us to create specific maps for both the minerals forming the terrigenous fraction and the different calcium carbonate polymorphs involved in the carbonatic component. A cross-linked behaviour between the carbonate facies and the terrigenous minerals involved in the calcium carbonate generation was found, suggesting the existence of a chemical control mechanism which, through dissolution-crystallization processes, constrains the mixed environment's long-term evolution. In the general framework of the region studied, these relations operate for the relative amount of plagioclase to calcium carbonate. The existence of dissolution and growth between both minerals, favoured by the high rate of removal, is proposed, yielding a final crossed pattern, representative of the steady-state. Furthermore, a specific analysis, restricted to the region of low rate of material removal and maximum amount of intermixed sediments, clearly shows an anisotropic distribution for every calcium carbonate polymorph (calcite and aragonite). These correlate with the biotite distribution, and can be connected to local variations in seawater Mg/Ca ratio, induced by biotite weathering.En este trabajo se analiza de forma especĂ­fica la distribuciĂłn espacial de cada uno de los minerales involucrados en sedimentos mixtos terrĂ­genos-carbonatados de la bahĂ­a de Bayona y se compara con la distribuciĂłn global de sedimentos, tal como resulta de anĂĄlisis granulomĂ©tricos, con el fin de determinar la existencia de diferentes mecanismos de mezcla entre los minerales de ambas fracciones. El contenido porcentual en peso de cada fase mineral, en muestras superficiales de sedimento, se determinĂł a partir de datos cuantitativos de DRX, empleando el mĂ©todo de Rietveld. Este procedimiento nos ha permitido realizar mapas especĂ­ficos de distribuciĂłn, tanto para cada mineral de la fracciĂłn terrĂ­gena como para cada uno de los diferentes polimorfos de carbonato cĂĄlcico en la componente carbonatada. Como resultado de este estudio comparativo, se ha encontrado una correlaciĂłn, en la distribuciĂłn espacial y granulomĂ©trica, de las facies carbonatadas y los minerales terrĂ­genos implicados en la generaciĂłn de carbonato cĂĄlcico. Un posterior anĂĄlisis de este resultado sugiere la presencia de mecanismos quĂ­micos de control que regulan la interacciĂłn entre siliciclastos y carbonatos mediante procesos de disoluciĂłn-cristalizaciĂłn mediados por el agua del mar. El estudio se ha realizado a dos escalas. En el ĂĄmbito general de la bahĂ­a de Bayona, las relaciones de distribuciĂłn observadas entre plagioclasas y carbonato cĂĄlcico pueden ser explicadas, dentro del balance global del CaÂłâș disuelto en el agua del mar, mediante la meteorizaciĂłn quĂ­mica de las plagioclasas y la consiguiente generaciĂłn de carbonatos. En este caso, los patrones de distribuciĂłn reflejan la aproximaciĂłn a un estado estacionario mediante sucesivos eventos de mezcla asociados a la alta removilizaciĂłn material en el medio, tanto para la distribuciĂłn porcentual en peso como para la distribuciĂłn granulomĂ©trica entre ambos minerales. Finalmente, se realiza un anĂĄlisis particularizado en una regiĂłn con baja tasa de removilizaciĂłn y donde la interacciĂłn entre sedimentos de ambas fracciones es mĂĄxima. El resultado muestra claramente una distribuciĂłn espacial anisĂłtropa para cada uno de las fases de carbonato cĂĄlcico (calcita y aragonito). La abundancia relativa de cada uno de los polimorfos, asĂ­ como el contenido en MgÂłâș de la calcita, ha sido correlacionado con la distribuciĂłn de la biotita y explicado a partir de las diferencias de solubilidad en funciĂłn de la alta relaciĂłn MgÂłâș /CaÂłâș en el agua de mar que resulta, localmente, de la meteorizaciĂłn quĂ­mica de dicho mineral.Instituto Español de OceanografĂ­

    COVID-19 outbreaks in a transmission control scenario: challenges posed by social and leisure activities, and for workers in vulnerable conditions, Spain, early summer 2020

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    Severe acute respiratory syndrome coronavirus 2 community-wide transmission declined in Spain by early May 2020, being replaced by outbreaks and sporadic cases. From mid-June to 2 August, excluding single household outbreaks, 673 outbreaks were notified nationally, 551 active (>6,200 cases) at the time. More than half of these outbreaks and cases coincided with: (i) social (family/friends’ gatherings or leisure venues) and (ii) occupational (mainly involving workers in vulnerable conditions) settings. Control measures were accordingly applied

    Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

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    This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic
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