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The Hospitais pluton is an elliptical body, with its long axis oriented WNW-ESE, that belongs to the Évora Massif (Iberian Variscan belt). This intrusion has a quartz-dioritic composition, with plagioclase, quartz, amphibole (hornblende, but locally also cummingtonite) and biotite as the main mineral phases. Mafic microgranular enclaves in the quartz-diorite show the same minerals as the host, but with a greater abundance of amphibole and lower proportions of felsic minerals, especially quartz. U-Pb zircon ages obtained in one sample of the quartz-diorite and one sample of a mafic microgranular enclave gave identical ages, within error, of ca. 337 Ma. Geochemical data show that the quartz-diorite has a calc-alkaline signature with moderate enrichment in LILE/HFSE ratio (Th N /Y N : 2.71-11.43) and clear negative Ti and Nb-Ta anomalies (Th N /Nb N : 1.33-6.22). The composition of the enclaves shows that they do not represent direct melt compositions. Instead, their geochemical features (namely the abundances of Fe and Mn in variation diagrams and REE patterns in primitive mantle normalized diagrams) suggest that they correspond to mineral clustering formed during the previous crystallization stage of quartz-dioritic magma. Overlapping of mineral chemistry and Sr-Nd isotope compositions in the quartz-diorite and the enclaves provides further support to that conclusion. The values for [ 87 Sr/ 86 Sr] i and εNd i (calculated for 337 Ma) in the quartz-diorite vary from 0.706147 to 0.706491 and from −1.87 to −3.22, respectively. This isotope composition may be explained either by differentiation of a mafic magma extracted from a mantle wedge enriched by long lasting subduction processes, or by mixing between a mafic magma from a depleted mantle source and a crustal melt. In the second case, the most likely source for the felsic component should be meta-igneous rocks, like the Lower Cambrian Alcáçovas orthogneisses that outcrop in neighbouring areas.

explained by: (1) crystallization from melts with different compositions (felsic peraluminous to felsic-intermediate metaluminous; 0.001 < Th/U ratio < 0.5) and (2) transient temperature fluctuations in a system where anatectic felsic melts periodically underwent injection of more mafic magmas at higher temperatures. The two studied calc-alkaline granitoids do not include inherited zircons (pre-Carboniferous), probably because they were formed at the highest grade of metamorphism (T > 837 °C; granulite facies) and/or because they were derived from inheritance-poor felsic and mafic rocks from a previous cycle, as suggested by the internal structures of zircon cores. These Variscan magmatic rocks with crystallization ages estimated at ca. 336-335 Ma are spatially and temporally related to hightemperature metamorphism, anatexis, processes of interaction between crustal-and mantle-derived magmas and intra-orogenic extension that acted in SW Iberia during the Early Carboniferous.

Colour is a major argument that drives the decision of an architect in a specific architecture project and one of the most important characteristics and perceptible aspects of natural building stones. “Blue” limestones are building rocks, with different geological ages, typically used in several countries, and are known for their vulnerability to alteration, which causes colour change and the occurrence of unaesthetic patterns. Owing to this vulnerability, the conservation-restoration works in monuments, or new buildings constructed with “blue” limestone is extremely costly. Considering that the main limitation of this lithological variation is the chromatic change, a multidisciplinary approach was envisaged in this study to allow a closer insight into the chemical and mineralogical alterations and the microbial communities. Results obtained suggest that the inorganic alteration in the “blue” limestone may create favourable conditions for microbial growth and could lead to an increment in deterioration process.