Roofing Slate Deposits in the Iberian Peninsula

España es el principal exportador mundial de pizarras, debido tanto a la calidad excepcional de sus yacimientos, como a los avances tecnológicos que se han ido incorporando en los últimos años en el proceso productivo. El presente artículo describe de manera general los principales litotectos de la Península Ibérica, incluidos dentro del área noroeste del Macizo Ibérico Hespérico, y entre los que destacan los pertenecientes a la Formación Pizarras de Luarca, que en Portugal se correlaciona con la Formación Pizarras de Valongo. En total, en la Península Ibérica se pueden distinguir 12 distritos mineros de pizarra para cubiertas, los cuales son valorados como yacimientos según criterios de tipo minero y petrológico.The exceptional quality of the slate of northwest Spain and the new technological advances incorporated in the last years into the production process have made the country the largest roofing slate producer in the World. This article describes the main slate lithotecs of the Iberian Peninsula. Most of them belong to the Luarca Slates Formation, which in Portugal correlates into the Valongo Slates Formation. Following mining and petrological criteria, a total of 12 mining districts of the Iberian Peninsula have been evaluated as roofing slates deposits.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEConselleria de Industria y Minas de la Xunta de Galiciapu

Palaeoenvironmental significance of Late Permian palaeosols in the South-Eastern Iberian Ranges, Spain

The Late Permian (Wuchiapingian) Alcotas Formation in the SE Iberian Ranges consists of one red alluvial succession where abundant soil profiles developed. Detailed petrographical and sedimentological studies in seven sections of the Alcotas Formation allow six different types of palaeosols, with distinctive characteristics and different palaeogeographical distribution, to be distinguished throughout the South-eastern Iberian Basin. These characteristics are, in turn, related to topographic, climatic and tectonic controls. The vertical distribution of the palaeosols is used to differentiate the formation in three parts from bottom to top showing both drastic and gradual vertical upwards palaeoenvironmental changes in the sections. Reconstruction of palaeoenvironmental conditions based on palaeosols provides evidence for understanding the events that occurred during the Late Permian, some few millions of years before the well-known Permian-Triassic global crisis

New ichnites from the Middle Triassic of the Iberian Ranges (Spain): paleoenvironmental and paleogeographical implications

The Iberian Basin or its present-day expression, the Iberian Ranges, was refilled with red bed sediments of alluvial origin during the late Olenekian–Anisian period represented by the Cañizar (Olenekian–Anisian) and Eslida (Anisian) Formations, both commonly known as Buntsandstein facies. In the late part of the Anisian, the Tethys Sea reached the eastern side of the Iberian microplate, represented by the shallow marine facies of the Landete and Cañete Formations, also called Muschelkalk facies. The ichnites studied in this paper belong to the Anisian continental-marine transition in the SE Iberian Ranges. The Cañizar Formation shows the oldest Triassic footprints found in the Iberian Peninsula, consisting in swimming, uncomplete lacertoid three digit Rhynchosauroides traces with possibly resting (cubichnia) and furrowing (pascichnia) Cruziana/Rusophycus due to large triopsids. Specimens from Lacertoïd and Crocodiloïd groups have been collected in the Eslida Formation. Rhynchosauroides sp. is the most representative ichnospecies of the first group, while in the Crocodiloïd group, the presence of Chirotherium barthii Kaup 1835 and Isochirotherium cf coureli (Demathieu 1970) are distinctive. In the Landete Formation specimens are found from Crocodiloïd and Dinosauroïd groups. Brachychirotherium gallicum Willruth 1917, Brachychirotherium sp. and Chirotherium sp. are characteristic of the first one, and ‘Coelurosaurichnus’ perriauxi and cf Paratrisauropus latus as the most representative of the second group. Some of the specimens described here present ancestors in the Early Triassic and have been described in the Triassic of North America, Italy and France. Possible paleogeographical connections with faunas of SE France can be inferred. Based on different sedimentary structures and plant remains, the footprints are related to fluvial systems within huge flood plains, playa and shallow marine environments, with alternating dry and wet periods. The vertical ichnites distribution during the Anisian shows that the fauna modification was weak at a high clade level. In the Triassic of the Iberian microplate, there are no findings of traces prior to the Anisian, and the footprint content for the Middle Triassic is less diversified than in other neighbouring regions. By comparison with other western Pangea areas, there was a later appearance of the forms after the end-Permian mass extinction event in the studied areaDepto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEMinisterio de Economía y Competitividad (MINECO)UCM-BSCH-GR58/08pu

3D model generated from UAV photogrammetry and semi-automated rock mass characterization

This work develops a rock mass characterization of a limestone quarry in northern Spain based on a 3D model obtained by using photographs taken from an unmanned aerial vehicle (UAV) flight and structure-from-motion algorithms. This methodology permits to obtain photogrammetric information in a rapid and low-cost way. Geological planar facets (stratification, faults) are related to the tectonic history of a geological formation and permit assessing slope stability. The spatial orientation of planar features is usually measured with a compass and clinometer, which requires experience and knowledge, it is space limited, and sometimes hazardous. Geological 3D models can mitigate these limitations. A 3D point cloud generated from a series of images obtained using an UAV is included in the open-access applications DSE and FACET, which serve to determine the main discontinuity planes within a limestone quarry. Comparison of the results from software analyses with data hand-measured directly in the field reveals the effectiveness of the use of UAV to develop a virtual outcrop model that permits to obtain accurate measurements. The resultant quarry 3D model has been included in Sketchfab, an open access platform that permits easy and quick access and availability for a wide audience. This study shows that the use of UAV combined with structure-from-motion algorithms is of great interest for geosciences as well as other related disciplines such as mining or civil engineering, and can facilitate decision-making for policy makers and authorities. In addition, it is a technique of great use to develop rock mass characterization in a low-cost, rapid, and easy way, and permits to reach areas with difficult accessibility. This way, this methodology can also be very useful for geosciences teaching purposes, as a complement to traditional field lectures, or to develop virtual field trips and laboratories

Palaeoenvironmental implications of aluminium phosphate-sulphate minerals in Early–Middle Triassic continental sediments, SE Iberian Range (Spain)

The presence of Sr-rich aluminium-phosphate sulphate (APS) minerals in continental sedimentary rocks from the Cañizar and Eslida Formations along the eastern part of the Iberian Range (Spain) is considered as evidence of acidic and oxidising conditions during Early–Middle Triassic times. The formation of APS minerals occurred shortly after sedimentation, in early diagenetic stages, prior to the compaction of the sediments and most probably was related to the circulation of acidic meteoric waters. Such conditions might result from a sustained, damaged environment or from multiple environmental crises, but would have delayed the recovery of life after the end-Palaeozoic mass extinction. APSminerals occur as small disseminated and idiomorphic pseudo-cubic crystals (0.5 to 6 μmlong) or as massive and polycrystalline aggregates replacing fragments of fine- rainedmetamorphic rocks (mainlymetapelites). Textural data indicate that the formation of the APS minerals predated the quartz and illite cements, and that they resulted from the destabilisation of pre-existing minerals, as evidenced by the replacement of slate fragments by APSminerals and hematite and by the close association of the disseminated APS crystals and kaolinitewith altered detrital mica plates. Electronmicroprobe analyses and X-ray diffraction study of the APSminerals indicate a rather homogeneous composition in different parts of the basin, corresponding to solid solutions among woodhouseite, svanbergite, crandallite and goyazite. The sources of strontium in the APS minerals remain unclear. Phosphorous was primarily supplied by dissolution of detrital phosphates under acidic conditions, and sulphur derives from the weathering of pyrite

RPAS (Remotely Piloted Aircraft Systems) para la elaboración de salidas de campo virtuales como recursos docentes “flipped classroom” para Grados relacionados con Ciencias de la Tierra

El principal objetivo del Proyecto es continuar con el desarrollo de material docente geológico y de recorridos de interés geológico virtuales además del uso de RPAS (Remotely Piloted Aircraft System) aeronaves no tripuladas que permiten acercarse a zonas de difícil accesibilidad. Este proyecto pretende desarrollar prácticas de campo virtuales mediante el manejo de nuevas tecnologías, tanto usando métodos de adquisición y elaboración de datos geológicos (RPAS: Remotely Piloted Aircraft System) como para su presentación y uso de la información y comunicación (TICs)

A new triadotypomorphan insect from the Anisian (Middle Triassic), Buntsandstein facies, Spain

The species rubra sp. nov., a new triadotypomorphan insect from the Iberian Ranges, is described on the basis of a newly discovered specimen, found in fine grained sandstones of alluvial origin, in the lowermost part of the Eslida Formation (Buntsandstein facies), in the central part of the Iberian Ranges. The occurrence of a triadotypomorphan suggests an Anisian age of the Eslida Formation. The species represents the oldest Mesozoic insect described from Spain, and provides interesting information to better appreciate the process of ecosystems recovery after the Permian-Triassic boundary crisis. [RESUMEN] La especie rubra sp. nov., un nuevo insecto triadotipomorfo de la Cordillera Ibérica, es descrito en este trabajo en base a un nuevo espécimen hallado en un nivel de areniscas de grano fino de origen aluvial en la parte más baja de la Formación Eslida (facies Buntsandstein), en la zona central de la Cordillera Ibérica. La aparición de este triadotipomorfo confirma la edad Ansíense (Triásico Medio) de la Formación Eslida. La especie encontrada representa el insecto más antiguo hallado en el Mesozoico de España y una interesante información para comprender mejor el proceso de recuperación de los ecosistemas tras la crisis del límite Pérmico-Triásico

Mineralogy and modulus of rupture of roofing slate: Applications in the prospection and quarrying of slate deposits

The European norm UNE 12326 for roofing slate defines the mechanical properties of a slate tile through the Bending Strength test, which defines the modulus of rupture (MoR) of the tile. This MoR is related to the durability of the slate, and is one of its main commercial quality properties. During the prospection task previous to open a new slate quarry, it is crucial to define the MoR. The Bending Strength test needs proper slate tiles and a flexion press. To supply these slate tiles it is frequently necessary to open experimental quarry fronts, which are very expensive, and do not guarantee the viability of the quarry. Therefore, a method which could reduce the costs and time for the mechanical characterization would be very useful. In this work we have tried to relate the MoR to the mineralogical and petrographic characteristics of slate, using the Petrographic Examination test, also part of UNE 12326. This test contemplates the finding of a numerical index called Mica Stacking Index (MSI) which quantifies the mica layers fabric. We collected fifteen samples of roofing slates from the Northwest of the Iberian Peninsula and we studied them by using the Bending Strength and Petrographic Examination tests, plus mineralogical quantification using X-ray diffraction and measure of the illite crystallinity (Kubler Index) to determine the metamorphic grade. We have found a strong positive correlation between MoR values and MSI, and a negative correlation between MoR and Mica percentages. These correlations may be used to deduce the MoR, reducing costs during the exploitation labours in roofing slate mining, and also can be used in the quality controls on a working slate quarry