Characterization of serpentinites to define their appropriate use as dimension stone

Abstract: Many questions arise when considering the appropriate use of building stones such as serpentinites. The commercial names of these rocks, collectively grouped as Green marbles ,have no correspondence to their actual mineralogy, geochemistry and/or physical characteristics. Serpentinite being the hydrated product of an ultramafic parent rock and not a metamorphicproduct of limestone as implied by the term marble . However, the serpentinites most widely used for ornamental purposes come from India (e.g. Rajasthan Green, Emerald Green) and in these the original mineralogy has been almost completely converted into carbonates. By contrast,serpentinites from elsewhere (e.g. Vermont Verde Antique from the USA and Verde Pirineos from Spain) do preserve some of their original mineralogy. The different physical and chemicalbehaviour of carbonates and serpentine minerals can result in significantly different behaviour of commercial building stones. Thus, carbonates are resistant to weathering but suffer fromacidic cleaning agents in interior use; whereas serpentinites, with a high content of talc, used on external faces undergo an increase in volume and a consequent rapid degradation. Accurate and precise characterization of serpentinites, including information on their mineralogyand geochemistry (including major, trace and volatile elements together with oxygenisotopes), in conjunction with their physical properties, would enable architects to select the appropriate interior or exterior use of these handsome building stones

Interferencia entre la investigación y las actividades docentes: ¿problema u oportunidad?

Memoria ID-161. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2018-2019

Estudio de la microfracturación del basalto de Miraflores (Panamá)

Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Elaboración de modelo para demostración del funcionamiento de bulones

Memoria ID-057. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2013-2014

Las serpentinitas y su correctautilización en construcción

Las serpentinitas son rocas deextendida utilización como rocaornamental debido a su ampliagama de colores y su atractivadiversidad textural. Sinembargo, el desconocimientode su composición, tantoquímica como mineralógica,hace que en ocasiones su usono sea el correcto

Caracterización geotécnica y mineralógica de bentonitas. Comparativa de distintos métodos de análisis de tamaño de partícula

Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Structure and Mechanical Properties of the Dueñas Clay Formation (Tertiary Duero Basin, Spain): An Overconsolidated Clay of Lacustrine Origin

The Dueñas Clay Formation is considered an example of a deposit of lacustrine continental origin. It is formed mainly by overconsolidated clays and includes feldspathic arenites, and clayey and silty levels; however, in geotechnical projects it is considered a clay unit and treated as a whole. The structure of each level was assessed in the field, in thin sections, and by SEM in the case of the clayey level. In addition, identification, strength, deformation, and durability tests were undertaken according to the nature of the samples (grain size analysis, Atterberg Limits, point load test, direct shear tests, uniaxial compression tests, swelling pressure, and unidimensional consolidation tests). The durability test was used as a criterion for dividing the levels within the formation according to their behavior as soil or rock. It was observed that the proportion and type of carbonate cementation controls the way in which the material behaves, with sparithic cement increasing the strength. The clay levels are expansive due to the presence of smectite, which also influences their behavior under shear stress. In addition, the massive and laminar structure of the layers caused by the continental conditions, in addition to the processes of post-sedimentation, explain their low compressibility

Creación de modelos a escala de situaciones reales en distintas obras para estudiar el comportamiento geomecánico de materiales granulares y cohesivos

Memoria ID12-0264. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2012-2013

Creación de modelos a escala de situaciones reales en distintas obras para estudiar el comportamiento geomecánico de materiales granulares y cohesivos (II): presa de hormigón y efectos sísmicos en suelos

Memoria ID-0062. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2013-2014.En las asignaturas de Geotecnia y Mecánica de Suelos se presentan conceptos teóricos y modelos del terreno que pocas veces se pueden comprobar más allá de experimentos concretos en laboratorio. Estos modelos de la realidad tratan de asemejarse a obras concretas, en las que, por otra parte, lo que ocurre en el subsuelo permanece oculto, y por lo tanto habitualmente el comportamiento supuesto del terreno sólo puede comprobarse a través de medidas de auscultación, sin poder tener evidencias visuales que enfaticen la idoneidad de los conceptos e hipótesis teóricas. La recreación de modelos físicos en urnas transparentes es una herramienta de gran utilidad para que el alumno de las asignaturas antes mencionadas pueda ver el comportamiento del terreno y comprobar cómo reacciona ante la aplicación de cargas en superficie, deformándose o incluso llegando a romper, cómo se reorganiza ante la acción de fuerzas dinámicas (simulación de sismos), y visualizando la circulación del agua a su través y las implicaciones que ello conlleva. Para este proyecto se han montado en dos urnas de metacrilato, equipadas con varios piezómetros cada una de ellas, modelos que recrean el fenómeno de la licuefacción en terrenos arenosos ante una acción dinámica y la circulación de agua por debajo de una presa de fábrica

Crustal Imbrication in an Alpine Intraplate Mountain Range: A Wide-Angle Cross-Section Across the Spanish-Portuguese Central System

Intraplate ranges are topographic features that can occur far from plate boundaries, the expected position of orogens as described in the plate tectonics theory. To understand the lithospheric structure of intraplate ranges, we focused on the Spanish-Portuguese Central System (SPCS), the most outstanding topographic feature in the central Iberian Peninsula. The SPCS is an Alpine range that exhumes Precambrian-Paleozoic rocks and is located at >200 km from the northern border of the Iberian microplate. Here, we provide a P-wave velocity model based on wide-angle seismic reflection/refraction data of the central SPCS (Gredos sector). Our results show: (a) a layered lithosphere characterized by three major interfaces: Conrad, Mohorovicic, and Hales discontinuities, (b) an asymmetry of the crust-mantle boundary under the SPCS, (c) the extent of the Variscan batholith forming the main outcrops of Gredos, and (d) the thinning of the lower crust toward the south. This model suggests that the exhumation of the SPCS basement was driven by a south-vergent thick-skinned thrust system, developed in the southern part of the SPCS and that promoted crustal imbrication and a Mohorovicic discontinuity's offset under the SPCS. Thus, the deformation mechanisms of the crust seem to be controlled by the presence of the late- to post-Variscan granitoids that assimilated the Variscan mid-crustal detachment creating a new rheological boundary. This tectonic structure allowed the formation of Alpine crustal-scale thrust systems that eased coupled deformation of the upper and lower crust, leading to limited underthrusting of both crustal layers.Ministry of Science, Innovation and Competitiveness through the Project CIMDEF (CGL2014-56548-P)Spanish Government and the University of Salamanca (Beatriz Galindo grant BEGAL 18/00090)Grant IJC2018-036074-I, funded by MCIN/AEI/10.13039/501100011033Grants CGL2015-71692 (MINECO/ FEDER) and PID2020-118822GB-I00 (MCIN/AEI/10.13039501100011033