The Iberian Variscan orogen is notorious for its important granitic magmatism. New field data, petrography, U-Pb zircon geochronology (sensitive high-resolution ion microprobe and chemical abrasion−isotope dilution−thermal ionization mass spectrometry), mineral and whole-rock geochemistry, and Sr-Nd isotope geochemistry were used to define two magmatic pulses in Northwest Iberia (Europe). The first magmatic event (324−315 Ma), caused by radiogenic heat production in a thickened crust, produced syntectonic G1 granitoids formed by I- ± S-type granites−granodiorites containing mafic enclaves. Lower crust metaigneous ± metasedimentary ± upper-mantle sources are inferred for these magmas. Simultaneously, important volumes of syntectonic S-type granites (G2) were produced. Neoproterozoic and early Paleozoic metasedimentary rocks and Cambrian−Ordovician orthogneisses were the likely protoliths. This initial melting event reduced the fertility of the middle−lower crust and conditioned the subsequent magmatic pulse (294−287 Ma) that produced post-tectonic G3 and G4 granitoids in a thinner crust. Lithospheric delamination and asthenospheric upwelling are the proposed heat sources in this case. G3 includes S-type granites derived from sources that preserved fertile components. Simultaneously, a significant volume of G4, including mainly I-type granitoids, was produced by the melting of residual and unmelted sources left behind after the first melting event. These sources comprised restitic metasedimentary rocks and juvenile mafic, intermediate metaigneous rocks. Small mafic enclaves attest to the minor involvement of mantle-derived melts. This model of Variscan magmatism shows that most S-type granites initially occurred due to the presence of fertile lithologies. The depletion of these fertile protoliths conditioned the subsequent melting event, resulting in the formation of a majority of I-type granites.
The Rio Grande Rise (RGR) is the largest oceanic plateau in the South Atlantic and represents a key natural laboratory for understanding oceanic plateau formation, deep-sea circulation, ecosystem functioning, and ferromanganese crust development. This study presents a critical synthesis of current scientific knowledge on the RGR, integrating geological, geophysical, oceanographic, biological, and geochemical evidence published over the last two decades. Geophysical data reveal a complex tectono-magmatic evolution involving Late Cretaceous plume-related volcanism, crustal thickening, rifting, and subsequent subsidence. The structural framework of the plateau is dominated by the Cruzeiro do Sul Rift, which plays a central role in controlling sedimentation, magmatism, and seawater circulation. Oceanographic studies demonstrate that the interaction between the southern branch of the South Equatorial Current and the complex topography of the RGR generates intense internal tides and bottom currents, strongly influencing sediment transport and benthic habitats. Biological investigations indicate that the RGR hosts diverse deep-sea communities, including sponge grounds, cold-water corals, and associated fauna, whose distribution is tightly linked to geomorphology and hydrodynamics. Ferromanganese crusts occurring on the plateau preserve valuable geochemical records of oceanographic and redox conditions, although their spatial distribution, thickness, and metal budgets remain incompletely constrained. Despite major advances, significant knowledge gaps persist regarding crustal structure, sedimentary evolution, ecosystem functioning, and mineral formation processes. This review highlights these uncertainties and outlines research priorities necessary to improve understanding of oceanic plateaus and deep-sea systems in the South Atlantic.
This paper describes a methodology based on a software tool to optimize the analysis of the erosion of historic monuments and to quantify its extent and distribution. It applies to the digital models of monuments, generated either with photogrammetry or Lidar data. The tool is an add-on for Blender™, a popular and free software for 3D editing. Before running it, the user is expected to generate a surface representing the theoretical original surface of the monument, in contact with the areas of the monument not affected by erosion. When this surface is ready, the erosion analysis can be performed. The tool estimates the erosion by measuring the separation between the original surface and the eroded surface of the monument. The result is plotted on the original surface as a distribution of color shades related to the erosion intensity. The numerical results are also exported to a ".csv" file that can be opened in MS Excel for further analysis. This paper also presents the application of this methodology to two case studies affected by two different erosion processes (one anthropogenic and the other natural). The presented results validate and highlight the usefulness of the proposed tool.
En el presente trabajo se analiza la influencia del mecanismo de saturación en el tipo e intensidad del deterioro sufrido por materiales pétreos naturales y artificiales durante el ensayo de hielo-deshielo. Se consideran dos mecanismos de saturación: inmersión a presión atmosférica (fundamentado en la norma UNE-EN 12371:2011) y absorción capilar (modificación metodológica propuesta). Esta modificación persigue aproximar el ensayo acelerado en laboratorio a las condiciones naturales a las que se encuentran expuestos los materiales pétreos del patrimonio arquitectónico en los que la saturación capilares un mecanismo de absorción de agua más frecuente que la inmersión libre. Se han ensayado siete litotipos diferentes. Los resultados muestran un mayor deterioro cuando los materiales se saturan por inmersión libre a presión atmosférica, indicando una sobreestimación del daño por hielo-deshielo real en los materiales de construcción. Además, se observan diferencias en el patrón de deterioro según el mecanismo de saturación, siendo el mortero de cal el más vulnerable entre los materiales estudiados. Los diferentes resultados petrofísicos entre materiales ponen de manifiesto que el ensayo debe adaptarse a las propiedades intrínsecas del material analizado.
