Meso-Neoproterozoic basic-intermediate mafic granulites (metabasites) from the ∼1 Ga granulitic southwestern Oaxacan complex, Mexico, crustal evolution and phase equilibria modeling

Altres ajuts: acords transformatius de la UABThe basement of eastern Mexico is made up of Grenvillian granulite-facies metamorphic rocks, which constitute an inferred microcontinent named Oaxaquia. Proto-Oaxaquia oceanic arc reconstructions are related to the transition from Columbia to Rodinia supercontinents (∼1.5 Ga). This study focuses on the petrography, geochemistry, and phase equilibria modeling of metabasites from the southwestern Oaxacan Complex, the largest Oaxaquia outcrop. Southwestern Oaxacan Complex protoliths mainly correspond to gabbro/basalt. They constitute an assemblage apart from the rest of the Oaxacan Complex metabasites due to their Ti enrichment and SiO2 depletion related to post-magmatic/metamorphic processes. Southern study site metabasites correspond to the primitive root of the arc, mostly related to a divergent geotectonic setting. The other metabasites are related to the magmatic back/forearc active margin between proto-Oaxaquia and Amazonia craton. Phase equilibria modeling point to Zapotecan (last Grenvillian cycle) metamorphic peak conditions of 850 ± 25 °C and 1.0 ± 0.15 GPa from one garnet-amphibole bearing metabasite, and a later hydration episode (post-Grenvillian) of 760 ± 10 °C and 0.8 ± 0.20 GPa derived from one amphibole bearing metabasite. The time of incipient partial melting of the southwestern Oaxacan Complex is a pre-Zapotecan event (∼1 Ga). Mineral textures do not display significant processes related to the post-Zapotecan metamorphic retrogression, and only a few whole-rock light rare element patterns display strong enrichments

Secondary organic aerosol origin in an urban environment: Influence of biogenic and fuel combustion precursors

Source contributions of organic aerosol (OA) are still not fully understood, especially in terms of quantitative distinction between secondary OA formed from anthropogenic precursors vs. that formed from natural precursors. In order to investigate the OA origin, a field campaign was carried out in Barcelona in summer 2013, including two periods characterized by low and high traffic conditions. Volatile organic compound (VOC) concentrations were higher during the second period, especially aromatic hydrocarbons related to traffic emissions, which showed a marked daily cycle peaking during traffic rush hours, similarly to black carbon (BC) concentrations. Biogenic VOC (BVOC) concentrations showed only minor changes from the low to the high traffic period, and their intra-day variability was related to temperature and solar radiation cycles, although a decrease was observed for monoterpenes during the day. The organic carbon (OC) concentrations increased from the first to the second period, and the fraction of non-fossil OC as determined by C analysis increased from 43% to 54% of the total OC. The combination of C analysis and Aerosol Chemical Speciation Monitor (ACSM) OA source apportionment showed that the fossil OC was mainly secondary (>70%) except for the last sample, when the fossil secondary OC only represented 51% of the total fossil OC. The fraction of non-fossil secondary OC increased from 37% of total secondary OC for the first sample to 60% for the last sample. This enhanced formation of non-fossil secondary OA (SOA) could be attributed to the reaction of BVOC precursors with NO emitted from road traffic (or from its nocturnal derivative nitrate that enhances night-time semi-volatile oxygenated OA (SV-OOA)), since NO concentrations increased from 19 to 42 μg m from the first to the last sample

Conductas disruptivas y propagación de la COVID-19 en la ciudad de Granada

Este informe es el resultado de un proyecto de investigación y transferencia que nace en el marco institucional del Grupo Local de Lucha contra la Covid-19 del Ayuntamiento de Granada. El estudio articula un equipo de investigación interdisciplinar (sociología, ciencia política, criminología y salud pública). Su cometido es desvelar las creencias, actitudes y comportamientos de la ciudadanía de Granada ante la pandemia de la Covid-19 en un momento de post-pandemia. Sus resultados y conclusiones se desprenden del análisis del discurso de cuatro grupos de discusión y versan sobre la naturaleza de las conductas percibidas como disruptivas, el conflicto social que estas generan, la estigmatización social derivada del conflicto, el clima social crítico que lo alimenta y los fallos del sistema propiciatorios de tal clima social. Las recomendaciones que se ofrecen se apoyan en los resultados de la celebración de dos talleres de consenso con expertos, y persiguen permitir al Ayuntamiento y otras instituciones locales prevenir, gestionar y amortiguar los efectos de futuras crisis, en el marco de sus competencias.Ayuntamiento de GranadaUnión Europea a través del Fondo Europeo de Desarrollo Regional (FEDER) y la Consejería de Economía, Conocimiento, Empresas y Universidad, Junta de Andalucía,Plan Propio de Investigación y Transferencia de la Universidad de Granad

Hercynian Metamorphism in the Catalonian Coastal Ranges

Paleozoic rocks in the Catalonian Coastal Ranges are in their largestpart affectedby alow-tovery-low grade Hercynian metamorphism. Amphibolite facies conditions are only found in restricted areas such as the southwestern part of the Guilleries massif where upper amphibolite facies conditions are reached. Metamorphic grade increases from top to bottom of the Paleozoic stratigraphic sequence and the metamorphic peak is diachronous, being progressively older in the lower grade metamorphic zones. The isograd pattern, mineral assemblages, mineral chemistry and preserved reaction textures are consistent with a low pressure metamorphism possibly evolving from a previous Barrovian type event. The metamorphic climax in the high grade zone was reached after the seconddeformational phase. Calculatedpeak P-Tconditions are 620-640 OC and around 3.5 Kb . A latter episode of decompression from the maximum conditions to 1-2 Kb, with an associated temperature decrease to 530-550 OC, is recognized. The intrusion of late Hercynian granitoids produced contact metamorphic aureoles where the pyroxene-hornfels facies is locally reached

Fluid-fluxed melting and melt loss in a syntectonic contact metamorphic aureole from the Variscan eastern Pyrenees

Open-system behaviour through fluid influx and melt loss can produce a variety of migmatite morphologies and mineral assemblages from the same protolith composition. This is shown by different types of granulite facies migmatite from the contact aureole of the Ceret gabbro-diorite stock in the Roc de Frausa Massif (eastern Pyrenees). Patch, stromatic and schollen migmatites are identified in the inner contact aureole, whereas schollen migmatites and residual melanosomes are found as xeno- liths inside the gabbro-diorite. Patch and schollen migmatites record D1 and D2 structures in folded melanosome and mostly preserve the high-T D2 in granular or weakly foliated leucosome. Stromatic migmatites and residual melanosomes only preserve D2. The assemblage quartz-garnet-biotite- sillimanite-cordierite K-feldspar-plagioclase is present in patch and schollen migmatites, whereas stromatic migmatites and residual melanosomes contain a sub-assemblage with no sillimanite and/or K-feldspar. A decrease in XFe (molar Fe/(Fe + Mg)) in garnet, biotite and cordierite is observed from patch migmatites through schollen and stromatic migmatites to residual melanosomes. Whole-rock compositions of patch, schollen and stromatic migmatites are similar to those of non-migmatitic rocks from the surrounding area. These metasedimentary rocks are interpreted as the protoliths of the migmatites. A decrease in the silica content of migmatites from 63 to 40 wt% SiO2 is accompa- nied by an increase in Al2O3 and MgO+FeO and by a depletion in alkalis. Thermodynamic modelling in the NCKFMASHTO system for the different types of migmatite provides peak metamorphic conditions ~7-8 kbar and 840 °C. A nearly isothermal decompression history down to 5.5 kbar was followed by isobaric cooling from 840 °C through 690 °C to lower temperatures. The preservation of granulite facies assemblages and the variation in mineral assemblages and chemical composition can be modelled by ongoing H2O-fluxed melting accompanied by melt loss. The fluids were probably released by the crystallizing gabbro-diorite, infiltrating the metasedimentary rocks and fluxing melting. Release of fluids and melt loss were probably favoured by coeval deformation (D2). The amount of melt remaining in the system varied considerably among the different types of migmatite. The whole-rock compositions of the samples, the modelled compositions of melts at the solidus at 5.5 kbar and the residues show a good correlation