231 research outputs found

    Paleomagnetism from Deception Island (South Shetlands archipelago, Antarctica), new insights into the interpretation of the volcanic evolution using a geomagnetic model

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    Deception Island shows the most recent exposed active volcanism in the northern boundary of the Bransfield Trough. The succession of the volcanic sequence in the island is broadly divided into pre- and post-caldera collapse units although a well-constrained chronological identification of the well-defined successive volcanic episodes is still needed. A new paleomagnetic investigation was carried out on 157 samples grouped in 20 sites from the volcanic deposits of Deception Island (South Shetlands archipelago, Antarctic Peninsula region) distributed in: (1) volcanic breccia (3 sites) and lavas (2 sites) prior to the caldera collapse; (2) lavas emplaced after the caldera collapse (10 sites); and (3) dikes cutting pre- and the lower- most post-caldera collapse units (5 sites). The information revealed by paleomagnetism provides new data about the evolution of the multi-episodic volcanic edifice of this Quaternary volcano, suggesting that the present-day position of the volcanic materials is close to their original emplace- ment position. The new data have been combined with previous paleomagnetic results in order to tentatively propose an age when comparing the paleomagnetic data with a global geomagnetic model. Despite the uncertainties in the use of averaged paleomagnetic data per volcanic units, the new data in combination with tephra occurrences noted elsewhere in the region suggest that the pre-caldera units (F1 and F2) erupted before 12,000 year BC, the caldera collapse took place at about 8300 year BC, and post-cal- dera units S1 and S2 are younger than 2000 year BC

    High-resolution scan of the Pyrenean crustal structure combining magnetotelluric and gravity data

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    The Pyrenees have undergone complex geodynamic evolution starting with experiencing significant tectonic events during the Variscan Orogeny, followed by the intrusion of large granitic complexes during the late Variscan stage, then the collision between the Iberian and European plates during the Alpine Orogeny, and finally, Mesozoic extension. Despite extensive studies and the application of various geophysical methods (two-dimensional seismic reflection data, gravity, and long period magnetotellurics) to investigate the Pyrenean structure, there are still fundamental questions regarding its basement and cover architecture. Specifically, the geometry at depth of significant bodies such as the Late Variscan intrusive granites and Triassic evaporitic accumulations, remains unclear. To better understand these issues, we have conducted joint magnetotelluric and gravity surveys along a 60-kilometer-long transect, spanning the boundary between the Axial and South Pyrenean Zones. Our final geological interpretation shows that the La Maladeta batholith consists of two distinct granitic bodies related to different intrusive pulses. In addition, we identify important Triassic evaporitic accumulations at depth. This work shows the high potential of integrating two geophysical models for understanding the geological evolution of structurally complex areas. The magnetotelluric and gravity data are complementary, with each dataset providing a different resolution for investigating the basement and cover architecture of the Pyrenees. These resolutions depend on the varied petrophysical properties of the rocks involved, including water content and deformation grade

    Datación de la evolución volcánica combinando datos paleomagnéticos y modelización geomagnética: Isla Decepción (Islas Shetland del Sur, Antártida).

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    La combinación de 20 nuevas estaciones de paleomagnetismo, con 17 estaciones previas y un modelo geomagnético ha permitido establecer la evolución multiepisódica del edificio volcánico cuaternario de la Isla Decepción (Antártida). Se han analizado tres estaciones en brechas volcánicas y dos estaciones en lavas pertenecientes a los materiales extruidos con anterioridad al colapso de la caldera. Entre los materiales extruidos posteriormente al colapso de la caldera se han analizado 10 estaciones en lavas y cinco estaciones en diques que cortan a los materiales pre- y la base de los post-colapso de caldera. A pesar de la incertidumbre por el uso de promedios de datos paleomagnéticos, la correlación con el modelo geomagnético y la existencia de tefras a escala regional permiten establecer que las unidades pre-colapso de caldera (F1 y F2) son anteriores a 12.000 a AC, mientras que la caldera colapsó en torno a los 8300 a AC y las unidades posteriores al colapso de la caldera (S1 y S2) han extruido con posterioridad a 2000 a AC. The combination of 20 new paleomagnetic sites with 17 previous sites and a geomagnetic model has allowed establishing the multi-episodic evolution of the Quaternary volcanic edifice of Deception Island (Antarctica). Paleomagnetic analyses have been carried out in three sites from volcanic breccia and two sites from lavas of the pre- caldera collapse units. Among the post-caldera collapse units, 10 sites in lavas have been analyzed in addition to 5 sites in dikes that intrude pre- and the lower part of the post-caldera collapse units. Despite the uncertainty of using averages of paleomagnetic data, the correlation with the geomagnetic model and tephra layers occurrences allow establishing that the pre-caldera collapse (F1 and F2) are older than 12,000 yr BC, while the caldera collapse occurred at about 8300 yr BC and the post-caldera collapse units (S1 and S2) deposited after 2000 yr BC

    Anisotropy dependence of the fluctuation spectroscopy in the critical and gaussian regimes in superconducting NaFe1-xCoxAs single crystals

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    We investigate thermal fluctuations in terms of diamagnetism and magnetotransport in superconducting NaFe1-xCoxAs single crystals with different doping levels. Results show that in the case of optimal doped and lightly overdoped (x= 0.03, 0.05) crystals the analysis in the critical as well as in the Gaussian fluctuation regions is consistent with the Ginzburg-Landau 3D fluctuation theory. However, in the case of strongly overdoped samples (x >= 0.07) the Ullah-Dorsey scaling of the fluctuation induced magnetoconductivity in the critical region confirms that thermal fluctuations exhibit a 3D anisotropic nature only in a narrow temperature region around T-c(H). This is consistent with the fact that in these samples the fluctuation effects in the Gaussian region above T-c may be described by the Lawrence-Doniach approach. Our results indicate that the anisotropy of these materials increases significantly with the doping level

    Atención de la urgencia quirúrgica durante la pandemia COVID-19. Recomendaciones de la Asociación Española de Cirujanos

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    La infección por el nuevo coronavirus SARS-CoV-2 (enfermedad por coronavirus 2019 [COVID-19]) ha determinado la necesidad de la reorganización de muchos centros hospitalarios en el mundo. España, como uno de los epicentros de la enfermedad, ha debido asumir cambios en la práctica totalidad de su territorio. Sin embargo, y desde el inicio de la pandemia, en todos los centros que atienden urgencias quirúrgicas ha sido necesario el mantenimiento de su cobertura, aunque igualmente ha sido inevitable introducir directrices especiales de ajuste al nuevo escenario que permitan el mantenimiento de la excelencia en la calidad asistencial. Este documento desarrolla una serie de indicaciones generales para la cirugía de urgencias y la atención al politraumatizado desarrolladas desde la literatura disponible y consensuadas por un subgrupo de profesionales desde el grupo general Cirugía-AEC-COVID-19. Estas medidas van encaminadas a contemplar un riguroso control de la exposición en pacientes y profesionales, a tener en cuenta las implicaciones de la pandemia sobre diferentes escenarios perioperatorios relacionados con la urgencia y a una adaptación ajustada a la situación del centro en relación con la atención a pacientes infectados. New coronavirus SARS-CoV-2 infection (coronavirus disease 2019 [COVID-19]) has determined the necessity of reorganization in many centers all over the world. Spain, as an epicenter of the disease, has been forced to assume health policy changes in all the territory. However, and from the beginning of the pandemic, every center attending surgical urgencies had to guarantee the continuous coverage adopting correct measures to maintain the excellence of quality of care. This document resumes general guidelines for emergency surgery and trauma care, obtained from the available bibliography and evaluated by a subgroup of professionals designated from the general group of investigators Cirugía-AEC-COVID-19 from the Spanish Association of Surgeons, directed to minimize professional exposure, to contemplate pandemic implications over different urgent perioperative scenarios and to adjust decision making to the occupational pressure caused by COVID-19 patients

    Subsurface Geophysics and Geology (GEOFSU

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    [EN] The geophysics line at the IGME began in 1927 as a Geophysics Sectiondedicated to subsurface exploration. During all this time, it has been developed in order to support and give expert service in all IGME’s activities both as a geological service and public research institution, as well as a research and development work itself. On the other hand, in recent years the IGME has promoted a line of research aimed at the characterization and 3D modeling of geological structures and formations, the development of dedicated software and the evolution and sophistication of computer equipment. The new scenario of incorporation of the IGME to the CSIC as a national reference center in the field of Earth Sciences has allowed the establishment of the GEOFSUB Research Group (Subsurface Geophysics and Geology). It is constituted by 21 members who had been collaborating regularly of the IGME former scientific-technic areas Geophysics and remote sensing (Área de Geofísica y Teledetección) and Subsurface geology and 3D geological modelling (Área de Geología del Subsuelo y Modelización Geológica 3D). Our main differentiating element is our extensive knowledge of geophysical and geological techniques, which allows us to characterize the subsoil in an optimal waPeer reviewe
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