Catodoluminiscencia de carbonatos lacustres pérmicos de los Pirineos Occidentales: un modelo de cementación temprana en paleoacuíferos meteóricos asociados a lagos

Cathodoluminescence of Permian lacustrine carbonates from the Westem Pyrenees: a model for early cementation in meteoric aquifers associated with lakes. We present here a case-study of early diagenetic cementation in Permian lacustrine lithofacies (Aragón-Béarn and Basque Country Basins, western Pyrenees). Cathodoluminescence zoning in calcite cements shows a general non-luminescent-bright luminescent-dull luminescent sequence which we interpret as a result of the transition from the vadose and oxic phreatic environments to the progressively reducing phreatic ground waters. Vadose features and non-lumines-cent cements predominate in the more  pedogenically altered andlor subaerially exposed facies. The very early timing of the whole sequence and the differences in cementation among lacustrine, palustrine and alluvial plain facies emphasize the dependence of the aquifers on sedimentary subenvironments and lake level changes. The Permian model here described is applicable to early cementation in meteoric aquifers related to shallow, carbonate lakes. Our data agree with the well-known control of Fe and Mn contents on the cathodolurninescence of calcites and dolomites and the uncertainties of a quantitative relationship between chernical composition and luminescence. The proposed sensitizer role for Mg needs further testing

Texture and mineralogy influence on durability: The Macigno sandstone

The behaviour of ornamental stones in response to environmental changes or interactions is crucial when dealing with the conservation of cultural heritage.Weathering factors affect each rock differently, depending on structure, mineralogy, and extraction and implementation techniques. This work focuses on the Macigno sandstone, a dimension stone often employed in Tuscany over the centuries. A thorough mineralogical (optical microscopy, scanning electron microscopy and X-ray powder diffraction) and petrophysical characterization (i.e. mercury intrusion porosimetry, X-ray computed tomography, hygroscopic adsorption behaviour, ultrasounds, image analysis and capillary uptake) was made of the sandstone type extracted in the area of Greve in Chianti. The lithotype shows mineralogical (i.e. presence of mixed-layer phyllosilicates) and microporosimetric features, leading to a high susceptibility to relative humidity variation. Moreover, the influence of swelling minerals is related to weathering due to saline solution. The joint application of petrographic and petrophysical techniques allows an understanding of the characteristic weathering pattern of exfoliation (i.e. detachment of multiple thin stone layers, centimetre scale, that are sub-parallel to the stone surface)

Caracterización de la estructura constructiva de la fachada de las escuelas mayores de la universidad de salamanca. interpretación por combinación de técnicas de georradar y sondeos mecánicos

La caracterización de la fábrica constructiva de edificaciones previa a su restauración o evaluación de estabilidad requiere estudios históricos previos y análisis del estilo constructivo del momento de construcción. En ocasiones dicha información es limitada o requiere ser contrastada por métodos de caracterización directa. En este trabajo se aborda el análisis de la fachada principal de las Escuelas Mayores de Salamanca (“Fachada Rica”) a través de la caracterización geofísica por medio de georradar, de 3 sondeos horizontales y los resultados obtenidos del análisis constructivo con criterios histórico-artísticos. Los resultados obtenidos permiten identificar la correlación entre las unidades geofísicas identificadas en los sondeos, y evaluar la variabilidad lateral de dichas unidades. Constructive fabric characterization previous to restauration is required for the design and stability analysis. These studies include the integration of historical data and knowledge of building style at the construction period. Sometimes this information is limited or requires to be contrasted with present-day construction features. In this work the Escuelas Mayores de Salamanca main façade (“ Fachada Rica ”) is evaluated through the integration of three horizontal boreholes and the obtained results from the geophysical characterization by means of GPR and considering the artistic-historical construction criteria since its construction moment. The obtained results permit to identify the correlation between the de?ned geophysical units and the layers identi?ed in boreholes and to evaluate the lateral correlation of these boreholes along the whole analyzed façade

The Helicobacter pylori Genome Project : insights into H. pylori population structure from analysis of a worldwide collection of complete genomes

Helicobacter pylori, a dominant member of the gastric microbiota, shares co-evolutionary history with humans. This has led to the development of genetically distinct H. pylori subpopulations associated with the geographic origin of the host and with differential gastric disease risk. Here, we provide insights into H. pylori population structure as a part of the Helicobacter pylori Genome Project (HpGP), a multi-disciplinary initiative aimed at elucidating H. pylori pathogenesis and identifying new therapeutic targets. We collected 1011 well-characterized clinical strains from 50 countries and generated high-quality genome sequences. We analysed core genome diversity and population structure of the HpGP dataset and 255 worldwide reference genomes to outline the ancestral contribution to Eurasian, African, and American populations. We found evidence of substantial contribution of population hpNorthAsia and subpopulation hspUral in Northern European H. pylori. The genomes of H. pylori isolated from northern and southern Indigenous Americans differed in that bacteria isolated in northern Indigenous communities were more similar to North Asian H. pylori while the southern had higher relatedness to hpEastAsia. Notably, we also found a highly clonal yet geographically dispersed North American subpopulation, which is negative for the cag pathogenicity island, and present in 7% of sequenced US genomes. We expect the HpGP dataset and the corresponding strains to become a major asset for H. pylori genomics

Algunas reflexiones sobre la creación de Centros de Recursos de Ciencias Experimentales en los CEPs: Investigación de un modelo para la enseñanza/aprendizaje de la Geología

Se presenta un modelo en fase de desarrollo de Centro de Recursos Didácticos de Geología en el CEP nº 1 de Zaragoza dirigido fundamentalmente a profesorado de EEMM, Ciclo Superior de EGB y E.U. de Magisterio. Los materiales presentados se conciben como recursos al servicio del profesorado que pueden y deben ser utilizados para su propia formación y la de su alumnado en procesos de enseñanza/aprendizaje coherentes con los modelos educativos actuales

An Experimental Investigation of the Effects of Grain Size and Pore Network on the Durability of Vicenza Stone

The textural properties of a rock and the characteristics of its pore network are intrinsic variables to consider when investigating the resistance of rock to weathering. To establish the influence of these variables on the effectiveness and progression of weathering processes, two lithotypes of a limestone were analyzed with respect to their texture and porosity, and to their performance during artificial weathering experiments. The studied rock is Vicenza Stone, a bioclastic limestone with heterogeneous texture, variable grain size from fine to coarse, and high levels of open porosity (27\u201328%). Two sets of samples were obtained from a quarry, defining coarse-grained (CGV) and fine-grained (FGV) lithotypes of Vicenza Stone. Multiple techniques (optical microscopy, scanning electron microscopy, image analysis, mercury intrusion porosimetry, hygroscopicity, ultrasound, and water absorption) were used to characterize the texture and porosity of the limestone. The sample sets were subjected to freeze\u2013thaw (UNI 11186:2008, Cultural heritage\u2014Natural and artificial stone\u2014Methodology for exposure to freeze-thawing cycles, 2008) and salt-crystallization (partial continuous immersion method with a Na2SO4-saturated saline solution) weathering experiments to investigate the processes and progression of mechanical and chemical weathering. Differences in freeze\u2013thaw-induced micro-cracks and in the deposition of secondary micrite between the lithotypes show that the CGV has an overall higher susceptibility to freeze\u2013thaw weathering than FGV. Salt-weathering processes induced micro-crack formation, material dissolution, and secondary precipitation, suggesting the simultaneous occurrence of mechanical stress and chemical dissolution\u2013precipitation processes. FGV is more prone to salt-induced weathering than CGV, whereas CGV is susceptible to the wide thermal excursions of freeze\u2013thaw weathering

The role of mantle and crust in the generation of calc-alkaline Variscan magmatism and its tectonic setting in the Eastern Pyrenees

The lower structural levels of the Variscan orogen exposed in the Eastern Pyrenees reveal three genetically associated magmatic suites: (i) a batholitic sized calc-alkaline granitoid (Sant Llorenç – La Jonquera, SL–LJ); (ii) minor mafic intrusions with local ultramafic cumulates (Ceret and Mas Claret mafic complexes); and (iii) peraluminous leucogranite bodies. These suites were emplaced in a syn- to post-collisional setting during the Late Carboniferous – Early Permian (ca. 315–290 Ma) in an Upper Proterozoic-Upper Ordovician metasedimentary sequence. We carried out field and petrographic work and whole-rock geochemistry (including Sr–Nd radiogenic isotopes) in order to constrain the petrogenetic relationships between them and to determine the interplay of the igneous suites with the country rock. We compare geochemical data to those from the neighbouring massifs of the Pyrenees and Catalan Coastal Ranges. The granitoids and the mafic complexes underwent variable degrees of lower crustal assimilation as demonstrated by the Sr and Nd isotopic ratios of SL–LJ granitoids and mafic rocks. Contaminated gabbro-diorites are high in Fe and Zr and contain magmatic garnet in equilibrium with an Fe–Mg amphibole. A supra-subduction metasomatized mantle source for the mafic complexes is inferred. The magma that formed the SL–LJ granitoids was of intermediate composition and may have formed by differentiation of of magmas derived from partial melting of a subduction-metasomatized mantle caused by active subduction or mantle delamination or by partial melting of the lower crust triggered by underplating of mantle-derived mafic magmas. Leucogranite magmas formed later by partial melting of crustal rocks with compositions similar to the outcropping metapelites and orthogneisses. We deduce a retrograde cooling decompression path from 0.75 GPa down to 0.55 GPa from phase equilibria for a garnet-bearing diorite. This path is compatible with a local extensional context linked to a regional dextral strike-slip regime that provided space for the ascent and emplacement of the pluton. This strike-slip system is consistent with late-Variscan shear zones displacing Gondwana to the west with respect to Laurasia during the orogenic collapse.This work was benefited from the Spanish Commission for Science and Technology research projects CGL2015-66335-C2-2-R, PGC2018-096534-B-I00 (IBERCRUST) and PGC2018-093903-B-C22. It has also been financed by PID2020-117332GB-C21, PID2020-117332GB-C22,PID2019-109018RB-I00 and PID2020-117598GB-I00, funded by MCIN/AEI /10.13039/501100011033. C. Aguilar is indebted to prof. K. Schulmann and P. Sipska from the Centre for Lithospheric Research, Czech Geological Survey for their guidance and support over the past few year

Multiscale approach to rock porosity and its distribution

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