The Villalcampo Shear Zone (Zamora, Spain), geometry, kinematics and the physical conditions of the strain

[Resumen] En este trabajo se presenta una cartografía detallada de un sistema de cizalla que incluye la zona de cizalla de Villalcampo propiamente dicha y las bandas asociadas. Este sistema tiene carácter regional, afecta a granitos intruidos después de la segunda fase hercínica y a sus encajantes metamórficos en un área de al menos 150 Km2. El estudio geométrico y cinemático de las bandas, la distribución de las rocas de falla, así como el estudio microestructural han permitido interpretar todo el sistema como una cizalla subvenical dextra de carácter dúctil-frágil, que termina hacia el NW en un abanico extensional y que se prolonga hacia el SE en otra amplia área interpretada como un duplex extensional. El valor de la cizalla 'Y es de 1,55 y el desplazamiento mínimo calculado es de 3,7 Km. Todas las bandas de cizalla que incluye el sistema de Villalcampo y las venas o filones asociados pueden relacionarse con un único campo de esfuerzos en el que la trayectoria del esfuerzo principal al, subhorizontal y de dirección aproximadamente N-S sufre una desviación en la zona terminal de la banda en sentido diferente según el labio de que se trate, tal como propone Anderson (1951). Para caracterizar el régimen y los mecanismos de la deformación se ha realizado un análisis microestructural detallado de las rocas de falla y un estudio petrográfico y de la petrofábrica de las milonitas. Se concluye que los yacimientos de oro de Pino están controlados estructuralmente por este sistema de cizalla ya que aparecen en venas extensionales ocupadas por milonitas brechificadas; las condiciones de la deformación de carácter alternativamente dúctil-frágil habrtan permitido la migración de fluidos mineralizadores y el sellado de las fracturas en ciclos repetidos. Se propone como hipótesis que los yacimientos de estaño y wolframio que aparecen en la región de Villaseco-Almaraz de Duero puedan estar controlados también por el duplex extensional de este sistema de cizalla.[Abstract] The present work reports" on a detailed mapping of the Villalcampo shear system, including the Villalcampo shear itself together with related shears and veins. This regional shear system affects granites intruded after the second hercynian deformation phase and their metamorphic host rocks over an area of about 150 Km2. A st~ctural study of the shear bands, encompassing geometric and kinematic criteria and also the distribution of fault rocks, has allowed the authors to interpret the whole of the system as a ductile-fragile subvenical dextral shear spaying to the NW in an extensional fan that is prolonged to the SE over a broad area interpreted as an extensional duplex. The value of the shear strain, 'Y = 1.55, and the minimum displacement, s = 3.700 m, is calculated. The distribution of shear bands and veins is coherent with the notion of a single stress field where the principal stress, o"¡, is subhorizontal and has a N-S trajectory that deviates to the tips of the main shear, as proposed by Anderson (1951). With a view to gaining insight into the shearing regimen and the physical conditions of the deformation, a microestructural exploration of the fault rocks was carried out together with a petrographical and petrofabric study of the mylonites. It is concluded that the Pino ore veins -with Au mineralization- are structurally controlled by this shear system because they are related to the extensional veins infilled by brecchiated mylonites. Additionally, it is proposed that the deformation conditions would have alternated between brittle and ductile; this would have permited the migration and sealing of microfractures by mineralizing fluids during repeated cycles. As an hypothesis, it is proposed that the Sn and W ores situated in -the Villaseco -Almaraz area are possibly related to the extensional duplex

The q\textit{q}-metric naked singularity: A viable explanation for the nature of the central object in the Milky Way

In this work, we investigate whether the compact object at the center of the Milky Way is a naked singularity described by the $\textit{q}$-metric spacetime. Our fitting of the astrometric and spectroscopic data for the S2 star implies that similarly to the Schwarzschild black hole, the $\textit{q}$-metric naked singularity offers a satisfactory fit to the observed measurements. Additionally, it is shown that the shadow produced by the naked singularity is consistent with the shadow observed by the Event Horizon Telescope collaboration for Sgr-A*. It is worth mentioning that the spatial distribution of the S-stars favors the notion that the compact object at the center of our Galaxy can be described by an almost static spacetime. Based on these findings, the $\textit{q}$-metric naked singularity turns up as a compelling candidate for further investigation.Comment: Accepted for publication in Classical and Quantum Gravit

Sowing density effect on common bean leaf area development

Sowing density is a major management factor that affects growth and development of grain crops by modifying the canopy light environment and interplant competition for water and nutrients. While the effects of sowing density and plant architecture on static vegetative and reproductive growth traits have been explored previously in the common bean, few studies have focused on the impacts of sowing density on the dynamics of node addition and leaf area development. We present the results from two sites of field experiments where the effects of sowing densities (5, 10, 15, 20, 25 and 35 plants m-2) and genotypes with contrasting plant architectures (two each from growth habits I through III) on the dynamics of node addition and leaf area were assessed. Analysis of the phyllochron (°C node-1) indicated genotype and density effects (but no interaction) on the rate of node addition. While significant, these differences amounted to less than two days of growth at either site. In terms of leaf area development, analysis using a power function reflected large differences in the dynamics and final size of individual plant leaf area between the lower density (20 plants m-2) at the growth habit, but not genotype level. These differences in node addition and leaf development dynamics translated to marked differences between growth habits and sowing densities in estimated leaf area indices, and consequently, in the estimated fraction of intercepted light at lower densities

Characterisation of the fouling of an ultrafiltration polyethersulfone membrane fouled by an emulsion modelling lipids issued from Microalgae

International audienc

Análisis de la actividad científica de la Comunidad Autónoma de la Región de Murcia. Biomedicina 1999-2005.

An analysis of scientific activity in Biomedicine in Murcia between 1999-2005 is presented

Constraining the X-ray reflection in low accretion rate AGN using XMM-Newton, NuSTAR and Swift

An interesting feature in active galactic nuclei (AGN) accreting at low rate is the weakness of the reflection features in their X-ray spectra, which can result from the gradual disappearance of the torus with decreasing accretion rates. It has been suggested that low luminosity AGN (LLAGN) would have a different reflector configuration compared with high luminosity AGN, either covering a smaller fraction of the sky or simply having less material. Additionally, we note that the determination of the spectral index ($\Gamma$) and the cut-off energy of the primary power-law emission is affected by the inclusion of reflection models, showing the importance of using them to study the accretion mechanism, especially in the case of the LLAGN that have previously shown a high dispersion on the relation between $\Gamma$ and the accretion rate. Our purpose is to constrain the geometry and column density of the reflector in a sample of LLAGN covering a broad X-ray range of energy combining data from XMM-Newton + NuSTAR + Swift of a hard X-ray-flux limited sample of 17 LLAGN from BASS/DR2 with accretion rates $\lambda_{Edd}$=L$_{\rm Bol}$/L$_{\rm Edd}$<10$^{-3}$. We fit all spectra using the reflection model for torus (borus02) and accretion disk (Xillver) reflectors. We found a tentative correlation between the torus column density and the accretion rate, LLAGN shows a lower column density compared with the high-luminosity objects. We also confirm the relation between $\Gamma$ and $\lambda_{Edd}$, with a smaller scatter than previously reported, thanks to the inclusion of high-energy data and the reflection models. Our results are consistent with a break at $\lambda_{Edd}\sim10^{-3}$, suggestive of a different accretion mechanism compared with higher accretion AGN.Comment: Accepted for publication in Astronomy & Astrophysic

Estudio gravi-magnetométrico del margen continental argentino a partir de métodos automáticos, borde continental

En este trabajo se presenta un análisis de datos de anomalías del Campo Magnético Total (CMT) compiladas a partir de campañas oceanográficas y grillas globales actualizadas en el margen continental argentino entre las latitudes 35°S y 51°S. Los datos fueron procesados matemáticamente a fin de caracterizar fuentes o límites magnéticos en el borde entre las cortezas continental y oceánica (COB). Fueron aplicados los métodos de la señal analítica (SA), el ángulo tilt (TDR), y la segunda derivada vertical (SDV) en 3D. Se calcularon la deconvolución de Werner (DW) y la señal analítica 2D (SA2D), en perfiles transversales al margen, con el propósito de hallar la profundidad de las fuentes. La señal analítica mostró fuentes profundas coincidiendo a lo largo de los alineamientos magnéticos del Mesozoico M0- M4. La segunda derivada vertical expuso fuentes someras sobre la faja de la anomalía magnética G y los alineamientos magnéticos M0-M4, los cuales se mostraron controlados por el sistema de transferencia Río de La Plata y las zonas de fractura de transferencia (ZFT) Salado y Colorado. La delineación del valor nulo del TDR se ajustó tanto al borde oriental como al occidental de las cuñas buzantes hacia el mar (SDRs). Las profundidades de las fuentes obtenidas a través de DW y SA2D se compararon con modelos gravimétricos 2D. El estudio integral de las anomalías gravimétricas junto a las magnéticas proporcionó aportes al conocimiento de la conformación del margen y reafirma sus características de gran actividad volcánica.Eje: Estudio del Interior Terrestre.Facultad de Ciencias Astronómicas y Geofísica

Influence of plant density and growth habit of common bean on leaf area development and N accumulation

Crop yield requires leaf area to intercept solar radiation and to undertake photosynthesis, both of which depend on nitrogen (N) accumulation. Further, the amount of accumulated plant N at the beginning of seed fill serves as the reservoir for N required in synthesizing the proteins in developing seeds. For common bean (Phaseolus vulgaris L.), resolution of the basic characteristics limiting production is challenging because of variation in plant growth-habit and in wide-ranging plant spacing. Field experiments were undertaken at two low-latitude locations with three plant growth-habit types and six plant densities to measure canopy leaf area and leaf N accumulation at the beginning of seed fill. Plant spacing of 20 plants m−2 or more was sufficient to result in equal leaf area and N accumulation for all six plant genotypes at each location. However, the low-altitude, higher-temperature location had lower accumulated leaf N and yield than the high-altitude, cooler-temperature location. These results indicate attention needs to be given to physiological or agronomic approaches to overcome the negative impact of high temperature on N accumulation by common bean