Los arrecifes messinienses de Almería (S.E. de España)

En las cuencas neógenas de la provincia de Almería (sureste de España) afloran depósitos arrecifales muy bien desarrollados, de edad Messiniense. Del estudio de algunos de los arrecifes más conocidos se han deducido sus principales rasgos estratigráficos y su significado paleogeográfico. Los arrecifes se desarrollaron sobre las áreas marginales de las plataformas al tiempo que en las cuencas adyacentes más profundas se producía una sedimentación margosa. Por esta causa, las series estratigráficas acumuladas en cada uno de estos lugares difieren notablemente. Dentro del arrecife se distinguen varias facies relacionadas con los distintos subambientes de este último. Las facies de armazón está constituida por colonias de Porites en tubos verticales de hasta varios metros de altura, cementadas tempranamente en el ambiente submarino donde crecían, y muy resistentes a la erosión. La facies de talud, que presenta un buzamiento original de 10·25", está constituida por calcirruditas y calcarenitas que presentan cambios notables en el tipo de elementos esqueletales constituyentes conforme nos desplazamos hacia la cuenca. Las facies de transición talud distal-cuenca consiste en calcilutitas laminadas. La recons1rucción paleogeográfica del área estudiada muestra un archipiélago constituido por islas dispersas, la mayor parte de las cuales corresponden a las actuales sierras, las cuales, por aquel entonces, estaban ya parcialmente emergidas. Los arrecifes se desarrollaron como orlas que progradaron hacia la cuenca desde las islas. Por esta razón, los buzamientos de los taludes divergen en todas las direcciones y tienen una disposición radial. Posteriormente en estas zonas marginales se desarrollaron plataformas carbonatadas, no arrecifales, que en las áreas del sureste son típicamente oolíticas e intercalan estromatolitos. Los depósitos arrecifales han sido dolomitizados en la diagénesis. La disolución, posiblemente concomitante a la dolomitización, de los componentes esqueletales riginalmente aragoníticos confiere a los arrecifes una elevada porosidad intragranular, lo que los hace interesantes desde el punto de vista petrolífero como posibles roca de almacén. Finalmente se resaltan los rasgos principales de los arrecifes messinienses y se comparan con los de los arrecifes tortonienses que afloran en la misma área. [ABSTRACT] Well-developed Messinian coral reef deposits outcrop in the neogene hasins of Almería (Southeastem Spain). The study of some of the best known reefs leads to the establishement of their main stratigraphic features and of their paleogeographic meaning. Reefs grew on shelf marginal areas while, at the same time, marly sedimentation was taking place on adjacent deeper basins. Because of that, completely different stratigraphic sections accumulated in each place. Several sedimentary facies related to reef subenvironments can be distinguished. Reef framework facies is built up by Porytes. Vertical tube-like colonies, up to several meters high, were cemented early in the submarine environment and became highly resistant to erosion. Fore-reef facies (reef talus facies) dipping originally 10-25° are mainly composed by calcirudites and calcarenites showing changes in the type of skeletal constituents as we move toward the basin. Distal talus/basin transition facies consist of laminated calcilutites. The paleogeographical reconstruction shows an archipielago with scattered islands most of them corresponding to the present sierras which, at that time, were partly emerged. The reefs developed as fringes which prograded basinward from the islands. Thus radial pattems of talus originated. Later on broad shallow carbonate platforns, without reefs, developed on these reliefs, in the Southeastem outcrops the sediments tipically consisting of oolites and some interlayered stromatolite beds. Reef deposits were laler dolomitized during diagenesis. Intragranular porosity due to dissolution of primary aragonitic skeletal remains (and possibly accompanying dolomitation) is very high. That is why they are thought to be good potential oil reservoir. Major features of Messinian reefs have been finally outlined and compared with those who present the reefs of Tortonian age occurring in the same area

Oxfordian microbial laminites from La Manga Formation, Neuquén Basin, Argentina: Remarkable nanobacteria preservation

Exceptionally preserved stromatolites have been found in the shallow marine carbonate facies of the Callovian-Oxfordian La Manga Formation, in the Neuquén Basin (Argentina). The stromatolites exhibit planar and crinkle lamination, often disrupted by sheet-cracks, mudcracks, and fenestral structures, which indicate periodic subaerial exposure. These and other evidences suggest that these stromatolites grew in low energy upper intertidal to lower supratidal environments. They consist of fine micrite/microsparite crystal fabrics (with a remarkable lack of allochems) that define submillimiter alternations of dense laminae. Extensive SEM examinations of polished samples of the stromatolites reveal exceptional preservation of rod-shaped bacteria, coccoid like microorganisms, and abundant aggregates of framboidal pyrite. The rod-like bacteria consists of a network of irregular distributed filaments, which range from 150 nm to an uncommon 640 nm in length; diameters range from 54 nm to 90 nm. Subspherical bodies range in size between 70 and 89 nm. The presence of abundant framboidal pyrites is interpreted as the result of the metabolic activity of sulfate–reducing bacteria and decay of organic matter.Se describen estromatolitos excepcionalmente preservados en facies carbonáticas marinas someras en la Formación La Manga, de edad Calloviense-Oxfordiense, en la Cuenca de Neuquén (Argentina). Los estromatolitos muestran una laminación tanto planar como ondulada, frecuentemente alterada por estructuras de tipo fenestral, y sheet y mud-crack, que indican etapas de exposición subaérea. Estas y otras características sugieren que estos estromatolitos crecieron en ambientes de baja energía, intermareales altos y supramareales. Están constituidos por una fábrica de micrita-microesparita (con una destacada ausencia de aloquímicos) que constituyen alternancias submilimétricas de laminación densa. Estudios detallados con SEM sobre muestras pulidas revelan una preservación excepcional con morfología alargada, microorganismos tipo cocoide, y abundantes agregados de pirita framboidal. Las bacterias con morfologías alargadas están constituyendo una red irregularmente distribuida de filamentos que oscilan en tamaño desde 150 nm hasta, excepcionalmente, 640 nm en longitud; el diámetro oscila entre 50 nm y 90 nm. Las morfologías subesféricas oscilan entre 70 nm y 89 nm. La presencia de abundantes piritas framboidales es interpretada como resultado de una actividad metabólica de bacterias sulfato-reductoras y la descomposición de materia orgánica

Estudio preliminar del impacto óptico del soiling en testigos de vidrio, en un área semiurbana de Madrid, para aplicación en sistemas fotovoltaicos

CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMEN: El ensuciamiento (soiling) de los paneles solares disminuye la producción energética de las instalaciones fotovoltaicas. Dentro del proyecto PVCastSOIL, que investiga el soiling desde varias perspectivas, este trabajo presenta los resultados preliminares del estudio del impacto óptico del soiling en un sistema fotovoltaico experimental, no conectado a red, situado en la periferia de Madrid (España). Con el objeto de estimar cuánta luz solar incidente no alcanza las células solares de losmódulos fotovoltaicos debido al soiling, se instaló un mini-soporte que ha permitido exponer, con una inclinación de 35º, una serie de testigos de vidrio durante casi once meses. Midiendo sus espectros de transmitancia, se ha determinado que durante ese periodo el grado de soiling fue bajo (1-3% de pérdida de transmitancia). Por último, se comentan las mejoras aplicadas para continuar este estudio durante 2020, destacándose que el nuevo banco de pruebas de soiling permitirá exponer testigos de vidrio de mayor tamaño y comparar el grado de ensuciamiento para dos inclinaciones diferentes (8º y 35º).ABSTRACT: Soiling on solar panels hinders the energy production of photovoltaic facilities. Within the PVCastSOIL project, which researches soiling from several perspectives, this work presents the early results of the study of the optical impairment due to soiling on an off-grid experimental photovoltaic system located in the urban fringe of Madrid (Spain). In order to estimate how much incoming sunlight does not reach the solar cells of the photovoltaic modules due to soiling, a 35º-tilted mini-mount was installed for the outdoor exposure of a series of glass coupons during almost eleven months. From their transmission spectra measurements, it was concluded that during such period the degree of soiling was low (1-3% of transmission loss). Finally, some improvements adopted for the continuation of this study during 2020 are commented, highlighting among them a new soiling test bench which will allow using larger glass coupons as well as comparing the degree of soiling for two different tilt angles (i.e. 8º and 35º).info:eu-repo/semantics/publishedVersio

Palaeoenvironmental significance of middle Oxfordian deep marine deposits from La Manga Formation, Neuquén Basin, Argentina

The Callovian-Oxfordian of the Neuquén Basin (Argentina) is characterized by an extensive marine carbonate system (La Manga Formation) with a predominance of shallow and middle ramp deposits, although locally in tectonically controlled settings, deeper deposits also formed. These middle Oxfordian deeper deposits consist of mudstone-wackestone carbonates alternating with black shales and show marked centimetre-scale rhythmicity, probably controlled by the Earth’s orbit parameters, mainly precession and eccentricity. The present study was designed to examine these deposits in terms of their sedimentology, geochemistry, and small-scale stratigraphy in Arroyo Los Blancos, southern Mendoza Province, where they are exceptionally well exposed and preserved. Results indicate that the sediments were deposited in an anoxic to dysoxic, relatively deep, sea-floor environment as revealed by the presence of: a) organic-rich shales, b) undisrupted lamination in most facies, c) pyrite framboids, and d) absence or scarcity of trace fossils and benthic fauna. Thin beds of graded wackestone-packstone and accumulations of thin shells of Bositra bivalves indicate sporadic reworking of the sea floor by weak currents. Organic petrology, Rock-Eval pyrolysis and thermal maturity indicators were used to characterize TOC and different types of organic matter. Low pyrolysis S yields along with low hydrogen indices suggest poor kerogen convertibility. Vitrinite reflectance (%Ro) ranged from 2.39 to 2.97 with an average of 2.70. The thermal alteration index (TAI) was 4+(5), indicating overmaturity. A tectono-sedimentary model is proposed for these deposits. According to this model, the relatively deep, organic-matter rich facies of La Manga Formation would have been deposited in the deepest zones of topographic lows controlled by tilting and differential subsidence of tectonic blocks bounded by normal faults.These faults were probably inherited from previous extensional tectonics of Late Triassic - Early Jurassic age.Facultad de Ciencias Naturales y Muse

Palaeoenvironmental significance of middle Oxfordian deep marine deposits from La Manga Formation, Neuquén Basin, Argentina

[EN] The Callovian-Oxfordian of the Neuquén Basin (Argentina) is characterized by an extensive marine carbonate system (La Manga Formation) with a predominance of shallow and middle ramp deposits, although locally in tectonically controlled settings, deeper deposits also formed. These middle Oxfordian deeper deposits consist of mudstone-wackestone carbonates alternating with black shales and show marked centimetre-scale rhythmicity, probably controlled by the Earth’s orbit parameters, mainly precession and eccentricity. The present study was designed to examine these deposits in terms of their sedimentology, geochemistry, and small-scale stratigraphy in Arroyo Los Blancos, southern Mendoza Province, where they are exceptionally well exposed and preserved. Results indicate that the sediments were deposited in an anoxic to dysoxic, relatively deep, sea-floor environment as revealed by the presence of: a) organic-rich shales, b) undisrupted lamination in most facies, c) pyrite framboids, and d) absence or scarcity of trace fossils and benthic fauna. Thin beds of graded wackestone-packstone and accumulations of thin shells of Bositra bivalves indicate sporadic reworking of the sea floor by weak currents. Organic petrology, Rock-Eval pyrolysis and thermal maturity indicators were used to characterize TOC and different types of organic matter. Low pyrolysis S yields along with low hydrogen indices suggest poor kerogen convertibility. Vitrinite reflectance (%Ro) ranged from 2.39 to 2.97 with an average of 2.70. The thermal alteration index (TAI) was 4+(5), indicating overmaturity. A tectono-sedimentary model is proposed for these deposits. According to this model, the relatively deep, organic-matter rich facies of La Manga Formation would have been deposited in the deepest zones of topographic lows controlled by tilting and differential subsidence of tectonic blocks bounded by normal faults.These faults were probably inherited from previous extensional tectonics of Late Triassic - Early Jurassic age.[ES] El Calloviense-Oxfordiense en el norte de la Cuenca Neuquina (Argentina) estuvo caracterizado por el desarrollo de un amplio sistema de rampa carbonatada (Formación La Manga) en el que predominaron los depósitos de rampa media y somera aunque localmente, y debido a control tectónico, pudieron acumularse depósitos más profundos. Estos depósitos, de edad Oxfordiense medio, están expuestos y preservados excepcionalmente en la zona de Arroyo Los Blancos, al sur de la provincia de Mendoza, y su estudio sedimentológico, geoquímico y estratigráfico representan el objetivo de este trabajo. Consisten en carbonatos (mudstone-wackestone) con acumulaciones de finas conchas de bivalvos de tipo Bositra que indican retrabajamientos esporádicos del sustrato marino debido a corrientes de baja intensidad. Se han caracterizado diferentes tipos de materia orgánica y TOC mediante petrología orgánica, Rock-Eval Pyrolisis e indicadores de madurez térmica. Los bajos valores en el campo del S unido al también bajo índice de H sugieren una baja convertibilidad de Kerógeno. La reflectancia de la vitrinita (%Ro) tiene un rango que oscila entre 2,39 y 2,97, con una media de 2,70, mientras que el índice de alteración térmico (TAI) es de 4+(5) indicando sobremaduración. Se propone también un modelo tectono-sedimentario para estos depósitos. En este modelo, estas facies relativamente profundas y ricas en materia orgánica de la Formación La Manga estarían depositadas en la parte más deprimida de bajos topográficos controlados por una subsidencia diferencial y de pulsos en bloques marcados por fallas normales heredadas probablemente de una tectónica extensional durante el Triásico Superior-Jurásico Inferior.Peer reviewe

Long-term hydrological changes in northern Iberia (4.9–0.9 ky BP) from speleothem Mg/Ca ratios and cave monitoring (Ojo Guareña Karst Complex, Spain)

An absolute-dated stalagmite from Kaite Cave (Ojo Guareña Karst Complex, N Spain) provides a nearly continuous, high-resolution record of a proxy of regional precipitation patterns through the 4.9–0.9 ka BP interval. This record is based on the Mg/Ca ratio of the calcite and its variation through the stalagmite stratigraphy, which is interpreted to be primarily driven by changes in precipitation amount. The calibration of the proxy is supported by the present-day monitoring carried out in the cave for the last 10 years, which reveals a robust inverse relationship between the inter-annual/inter-decadal variability of rainfall and the Mg concentration of dripwaters and precipitating speleothems. The record of paleoprecipitation, based on 2400 Mg/Ca measurements, shows strong variability at inter-annual to inter-decadal scales, and more subtle but significant changes at secular to millennial scales. This long-term paleohydrological evolution outlines five successive intervals with consistent trends, which are bounded by abrupt shifts in the regional precipitation. These shifts took place at 4.65, 4.2, 2.6, and 1.3 ka BP. Significantly, the intervals of maximum precipitation of the whole record (around 4.9–4.65, 2.6–2.45, and 1.3–1.1 ka BP) can be related with episodes of minimum solar activity and correlated with cold climatic events elsewhere.Contribution to research projects 28 CGL2010-21499-BTE and CGL2013-43257-R of the Spanish R+D National Program 29 (MINECO) and research groups ‘‘Paleoclimatology and Global Change’’ and ‘‘Laser Induced 30 Breakdown Spectroscopy (LIBS)’’ from the UCM (Spain).Peer reviewe

Palaeoenvironmental significance of middle Oxfordian deep marine deposits from La Manga Formation, Neuquén Basin, Argentina

The Callovian-Oxfordian of the Neuquén Basin (Argentina) is characterized by an extensive marine carbonate system (La Manga Formation) with a predominance of shallow and middle ramp deposits, although locally in tectonically controlled settings, deeper deposits also formed. These middle Oxfordian deeper deposits consist of mudstone-wackestone carbonates alternating with black shales and show marked centimetre-scale rhythmicity, probably controlled by the Earth’s orbit parameters, mainly precession and eccentricity. The present study was designed to examine these deposits in terms of their sedimentology, geochemistry, and small-scale stratigraphy in Arroyo Los Blancos, southern Mendoza Province, where they are exceptionally well exposed and preserved. Results indicate that the sediments were deposited in an anoxic to dysoxic, relatively deep, sea-floor environment as revealed by the presence of: a) organic-rich shales, b) undisrupted lamination in most facies, c) pyrite framboids, and d) absence or scarcity of trace fossils and benthic fauna. Thin beds of graded wackestone-packstone and accumulations of thin shells of Bositra bivalves indicate sporadic reworking of the sea floor by weak currents. Organic petrology, Rock-Eval pyrolysis and thermal maturity indicators were used to characterize TOC and different types of organic matter. Low pyrolysis S yields along with low hydrogen indices suggest poor kerogen convertibility. Vitrinite reflectance (%Ro) ranged from 2.39 to 2.97 with an average of 2.70. The thermal alteration index (TAI) was 4+(5), indicating overmaturity. A tectono-sedimentary model is proposed for these deposits. According to this model, the relatively deep, organic-matter rich facies of La Manga Formation would have been deposited in the deepest zones of topographic lows controlled by tilting and differential subsidence of tectonic blocks bounded by normal faults.These faults were probably inherited from previous extensional tectonics of Late Triassic - Early Jurassic age.Facultad de Ciencias Naturales y Muse

The Anisian continental-marine transition in Sardinia (Italy): state of the art, new palynological data and regional chronostratigraphic correlation

The scarce evidence of paleontological records between the upper Permian and the Anisian (Middle Triassic) of Western Europe could reflect (1) large stratigraphic gaps in the continental successions and/or (2) the persistence of disturbed conditions after the Permian–Triassic Boundary extinction event and the succession of ecological crises that occurred during the Early Triassic. In this context, the study of palynological associations, integrated with the stratigraphical and sedimentological data, plays a key role in dating and correlating the successions of the Western European domain and improves our understanding of environmental and paleoclimatic conditions. In some cases, pre-Anisian paleontological evidence is lacking, as in Sardinia (Italy), where a long gap encompasses the middle Permian (pars) to late Lower Triassic successions. Although fragmented and disseminated, the continental Lower-Middle Triassic sedimentary successions (Buntsandstein) of Sardinia have proved crucial to our understanding of the evolution of the southern edge of the Paleo-Europe and the different timings of the Tethys transgression (Muschelkalk facies) in some of these areas. Various paleogeographic reconstructions were attempted in previous works, without providing any consensus on the precise position of Sardinia and its surrounding seaways in the Western Tethys domain during this time interval. At present, the configuration and distribution of the subsiding and emerging landmasses and the temporal development of the transgressions of the Western Tethys during the Middle Triassic remain unclear. This work focuses on the stratigraphical, sedimentological and palynological aspects of three Middle Triassic continental-marine sedimentary successions in Sardinia, with particular attention to the analysis of the palynological associations sampled there, and it also provides a detailed review of all previous palynological publications on the Sardinian Anisian. The studied successions are: Su Passu Malu section (Campumari, SW Sardinia), Arcu is Fronestas section and Escalaplano section (Escalaplano, Central Sardinia). These sections were also correlated to other significant sections in the SW (Scivu Is Arenas) and NW (Nurra) parts of the island