Pérdida del pulido de diferentes mármoles comerciales en ambientes salinos

Este artículo cuantifica la pérdida de pulido que sufren los mármoles cuando entran en contacto con disoluciones salinas. La pérdida de pulido (cuantificada como el incremento de rugosidad superficial) es debida a la disolución que sufren los cristales de calcita, y se compara esta tasa de disolución con la estabilidad de los mármoles dolomíticos.Este trabajo se enmarca en el Proyecto Maternas (S0505-MAT/000094, Comunidad de Madrid)

Carbonates and Sulfates in Hot Spring Microbialites (Baños de Mula, Betic Range)

In this paper the association of various minerals, mainly carbonates, to microbial mats that cover the surfaces of a hot spring is documented. In addition, the influence of microorganisms in the formation of the travertine is discussed.This study was financed by the Spanish Ministry of Economy and Competitivity (Projects CGL2011-25162 and CGL2011-26781)

Travertine of Baños de Mula. A stone with sedimentological and archaeological interest

Los travertinos coloreados de Baños de Mula fueron utilizados como roca dimensional entre otros sitios, en el Teatro Romano de Cartagena (Travertino Rojo de Mula). Esta roca tiene buenas propiedades mecánicas y buen comportamiento hídrico. Estas propiedades presentan fuerte anisotropía, relacionada con su característica estructura bandeada definida visualmente por cambios en la coloración y en la distribución de los poros. Sus características texturales, muestran el predominio de niveles constituidos por cristales fibrosos y fibroso-radiados, con una fase cementante tardía de oxihidróxidos de Fe, así como morfologías micríticas del tipo de colonias bacterianas. Ambos rasgos pueden relacionarse con actividad bacteriana. Todos estos datos apuntan a favor de una génesis relacionada con aguas termales. Este hidrotermalismo está en relación con fallas activas y se mantiene activo en la actualidad (Balneario de Baños de Mula).The coloured travertine of the Baños de Mula,were used as dimensional stone among other sites in the Roman Theatre in Cartagena (Red Mula Travertine). This rock has good mechanical properties and water behavior. These properties show strong anisotropy related to the characteristic bedding planes visually defined by changes in the color intensity and pore distribution. Their textural features show the prevalence of layers consisting of fibrous and fibrous-radiated crystals with a late stage cementing Fe oxyhydroxides and micritic aggregates following colonial bacterial morphologies. Both features may be related to bacterial activity. All these data point in favor of a genesis related upwelling of thermal waters. These hydrothermal processes are connected with hydrothermal circulation along the active faults, and are manifested at present in the hot springs of Baños de Mula.Este trabajo ha sido parcialmente subvencionado por el proyecto Geomateriales (P2009/MAT-1629) de la Comunidad de Madrid

Some colored travertines from the Betic Range (SE Iberian Peninsula): their geological setting and petrophysical properties

En la zona Bética Externa, se encuentran depósitos de travertinos coloreados de valor como rocas ornamentales cuyas características petrofísicas son poco conocidas. Están en relación con fallas activas. Las canteras de travertino se sitúan en Alhama de Almería, Albox (Almería) y Baños de Mula (Murcia). Estos travertinos forman parte de la última etapa del relleno de las cuencas terciarias postectónicas béticas (Pleistoceno) y generalmente aparecen espacialmente asociados a episodios tobáceos. El objetivo de este trabajo es definir las facies de estos travertinos y las características petrofísicas que presentan con vistas a su utilización como roca ornamental. Predominan en ellos las facies bandeadas (1 - 10 cm). Su porosidad es variable (5 - 15%) consistente en una microporosidad bastante homogénea, con moda (0.005-0.05 μm) ligada al carbonato micrítico, y una familia de poros menos seleccionada entre 0.05-2 μm asociada a cristales de mayor tamaño. La macroporosidad de tamaño y disposición variable es un rasgo característico de estos travertinos. El coeficiente de absorción capilar es muy anisótropo y varía mucho en los diferentes travertinos estudiados. El valor mínimo encontrado en travertinos comercializados ha sido de 1.42 (g/m2s0.5) en dirección oblicua a la estructura en el travertino Rojo Alhama y el máximo de 10.71(g/m2s0.5) en dirección paralela a la estructura en el travertino de Albox. Su resistencia es notablemente anisótropa, encontrando valores de resistencia a compresión que pueden llegar a alcanzar 68 MPa en dirección perpendicular al bandeado. Cortados en dicha dirección constituyen una roca ornamental de buena calidad dentro de la categoría de mármoles comerciales.The Betic Range contains several colored travertine deposits which were formed during the last stage of the post-tectonic Tertiary-Quaternary (Pleistocene) basin refill. Associated with active faults, these travertines are quarried in Alhama de Almería, Albox (Almería) and Baños de Mula (Murcia) for subsequent use as ornamental stone. The aim of this study was to characterize their facies and physical properties in order to establish their suitability for use as an ornamental stone. The main facies was banded (1-10 cm), and the travertines presented variable porosity ranging from 5-15%. Porosity is related to travertine texture: a) fairly homogeneous microporosity, with a mode between 0.005 and 0.05 μm, is linked to micritic carbonate; and b) a porosity mode varying widely from 0.05 to 2 μm is associated with larger crystals. A characteristic feature of these travertine deposits was their macroporosity of variable size and distribution. The coefficient of capillary absorption was highly anisotropic and presented very different magnitudes in the different travertines studied. A minimum value of 1.42 (g/m2 s0.5) was observed in the commercial Red Alhama travertine, in an oblique direction to the structure, while the maximum value of 10.71 (g/m2 s0.5) was found in Albox travertine deposits, in a parallel direction to the structure. Strength was markedly anisotropic, attaining compressive strength values as high as 68 MPa in the direction perpendicular to the bedding planes. When cut in this direction, the travertines studied yield good quality ornamental stone within the category of commercial marble.Este trabajo ha contado con la ayuda del MEC: Proyecto CGL2006-05027y de la Comunidad de Madrid: Proyectos Geomateriales (S2009/Mat-1629 y S2023/MIT 2914)

Diagnosis of the state of the old Alicante provincial hospital, currently housing the "MARQ" (Alicante archaeological museum)

This study deals with the old Alicante Provincial Hospital building, and aims to determine the systems and materials used in its construction, and their state of preservation. The reason behind this project was to identify the causes of damage found there prior to the intervention that converted it into the Alicante Archaeological Museum (MARQ). To carry out the study, historical information on the building and copies of the original plans were gathered from the Alicante Municipal Archive, Provincial Council and the Institute of Architects. During field work, the building was visited both internally and externally and these visits were used to make graphic records of its current condition. Samples were also taken of the different materials for analysis in the University of Alicante laboratories, using equipment in the Science Faculty and the Higher Polytechnic School. To be more exact, samples of the materials were prepared to undergo physical tests as per RILEM standards (calculation of real density RD And open porosity OP), X-ray diffraction analysis (hereafter XRD), thin sections (hereafter TS) for study in the petrographic microscope and preparations for study in the scanning electron microscope (SEM). In accordance with the data obtained from the study, proposals were made concerning the preservation and repair options available concerning the different elements that formed part of the building and that were to be maintained in the proposed project or, where applicable, replaced. The Museum was restored following the criteria described herein and is now one of Alicante’s flagship buildings, where intervention has allowed an example of obsolete hospital architecture to be converted to a new use

Impact of salt and frost weathering on the physical and durability properties of travertines and carbonate tufas used as building material

This study aims to understand the effect of salt and frost crystallisation on the petrophysical and durability properties of representative types of travertine and carbonate tufas. Results demonstrate that the studied travertines and tufas exhibit a very high durability against salt and ice crystallisation cycles, compared to carbonates rocks with similar porosity values. The variation of the loss of mass, effective porosity, capillary absorption coefficient, ultrasonic wave velocity and attenuation, and compressive strength was scarce during weathering tests. The evolution of petrophysical properties was slightly more intense after 30 cycles of salt crystallisation than 100 cycles of freeze–thaw. Petrophysical and durability properties of the travertines and carbonate tufas depend on porosity fraction and on the manner in which the vuggy porosity is connected. In the travertine facies, vuggy macropores show little connection and can be considered as separate-vug porosity. Their addition to interparticle porosity increases effective porosity and reduces their mechanical strength but does not significantly increase capillary transport and the effectiveness of salt and ice action over the stone. On the contrary, in the carbonate tufas, vugs act as touching-vug pores, as capillary imbibition coefficients reveal. However, scanning electron microscopy displays that they underwent microcracking processes related mainly to both thermal stresses and/or ice and salt pressures. These microcracks present little connection, and they do not enhance noticeably the water flow or decrease the mechanical properties. These results are finally discussed in terms of a nonlinear decay pattern, which with long periods of apparent stability might be followed by rapid and catastrophic decay.This study was financed by the Spanish Ministry of Education and Science (MEC) through the Research Project CGL2006-05027/BTE and Community of Madrid (S2023/MIT 2914). A pre-doctoral research fellowship was awarded to N. Cueto by the MEC

Depositional sedimentary controls on sepiolite occurrence in Paracuellos de Jarama, Madrid basin

La presencia de sepiolita en los sedimentos neógenos (Aragoniense medio y superior) aparece ligada a paleoambientes de orla distal en abanicos aluviales. Dentro de ellos la formación de sepiolita tuvo lugar en charcas de carácter más o menos perenne próximas al borde de un lago salino, así como a cuerpos de agua desarrollados en la orla en momentos de retrogradación o estabilización relativa de los abanicos. Un último ambiente de formación de sepiolita son los perfiles de calcreta que aparecen ampliamente desarro­llados en estas zonas distales del sistema aluvial

Rocas ornamentales porosas del Mioceno marino de Levante (Alicante-Murcia-Albacete)

Petrological and technological data from some common dimension stones from Marine Miocene deposits of Southeastern Spain are described. Two main types of materials are distinguished: a) allochemical calcareous rocks - biocalcarenites with foraminifer whole tests, as main fossiliferous component: biocalcarenites of the Medio Vinalopó, and b) lumaquelles: biocalcirrudites with bioclasts of briozoans, bivalves, corals, red algae... of the Prebetic of Albacete-Murcia. Both types of dimension stones have very similar technological properties, the average values as compressive strenght and the modulus of rupture of calcarenites are higher than this of lumaquelles and the weight loss after 25 freezing-thawing cycles of calcarenites (durability) are too moderately higher than this of lumaquelles.Este trabajo ha sido subvencionado por la DGICYT: Proyecto PB95-0680

Los mármoles comerciales “Marrón Imperial” y “Marrón Emperador” (S.E. España). Caracterización petrológica y criterios de exploración

Los mármoles comerciales "Marrón Imperial" y "Marrón Emperador" son dolomías brechoides que de acuerdo con la clasificación del MIA pertenece al Grupo C de mármoles comerciales. Se determinan sus parámetros petrofísicos según la norma UNE. Sus rasgos petrológicos se estudian mediante microscopio petrográfico de luz transmitida y microscopio electrónico de barrido (MEB) (en modo de electrones secundarios y electrones retrodispersados). Estas rocas son básicamente dolomías mesocristalinas con abundantes vénulas calcíticas politexturales relacionadas con procesos de brechificación y de dolomitización. Rasgos kársticos aumentan la complejidad petrológica de estas rocas ornamentales cuyo litosoma son las dolomías masivas del Cretácico Superior (¿Turoniense?) del dominio Prebético Externo. El material explotado pertenece a una alineación morfoestructural que va desde Jumilla hasta el NE de Caudete y está relacionado con la falla Jumilla-Yecla-Caudete-Font de la Figuera. La relación entre esta falla y las dolomías turonienses son el principal criterio de exploración de estas rocas ornamentales.The "Marrón Imperial" and the "Marrón Emperador" commercial marble are brecciated dolomite rocks that, in agree with the soundness classification of MIA, belongs to the Group C of the commercial marbles. Petrophysical parameters of stones has been obtained using de UNE NORM (Spanish normalised test). The petrologic features have been defined from light microscopy and SEM data (secondary electrons and back scattered electrons modes). "Marrón Imperial" and "Marrón Emperador" are mesocrystalline dolostones with a reticulate of calcite veins, which are polytextural and are related to both brecciation and dedolomitization processes. Karstic features increase the petrologic complexity of this dimensional stone. The host lithosomes of "Marrón Imperial" and "Marrón Emperador" marbles are the massive dolostones of Upper Cretaceous (Turonian?) age of Outer Prebetic Domain. The quarried material outcrops from Jumilla to NE Caudete; Villena-La Encina, Jumilla (Fuente and Cingla Mountains) Yecla (Magdalena Mountains). Caudete and Yecla are the most important areas for extraction at the moment. The tectofacies that are the main responsible of the aesthetic properties of the Marrón Imperial and Marrón Emperador commercial marbles which main outcrops are probably related to the Jumilla-Yecla-Caudete-Font de la Figuera near strike-slip fault and associated events. The main exploration criteria from this type of commercial marble are the fault line distribution, and their influence over Turonian dolostones.Este trabajo forma parte del Proyecto AMB 93-0019 subvencionado por la CICYT

Las casas palacio del siglo XVIII, sede del Museo Provincial de Bellas Artes de Alicante (MUBAG)

El Museo de Bellas Artes de Alicante (MUBAG) ha sido instalado en dos casas palacio del siglo XVIII realizadas en piedra natural