Procedencia y modelo diagenético de las areniscas de Facies Utrillas en la cordillera Ibérica (Umbral de Ateca) y la meseta norcastellana

Las facies Utrillas de la Cordillera Ibérica, en los alrededores del Umbral de Ateca y en la Meseta norcastellana, provincia de Soria, son un depósito detrítico formado en un ambiente sedimentario de sistemas aluviales que se puede subdividir en dos unidades (Meléndez y Vilas, 1980): la inferior, compuesta por canales y barras de litología conglomerática y areniscos a, se caracteriza por haberse depositado en un medio aluvial de tipo trenzado; y la superior, integrada porlutitas con cuerpos intercalados de areniscas canaliformes originada en un medio fluvial mucho más maduro. Las areniscas de las facies Utrillas son fundamentalmente arcosas y subarcosas, con bajos contenidos en fragmentos de roca y una matriz de tipo silcreta debida a procesos edáficos. La presencia del feldespato-K es el factor determinante de los procesos diagenéticos más importantes sufridos por estas areniscas; aparición de epimatriz de caolinita-ilita, pore filling de caolinita, cierre de la porosidad primaria y generación de porosidad secundaria por disolución de dichos feldespatos. Otros procesos diagenéticos menos significativos y más localizados hacia el techo de las series, lo constituyen: cementos de calcita, dolomita y anhidrita, así como clay coats de esmectita e interestratificados ilita-esmectita. Las areniscas estudiadas muestran un claro ejemplo de procedencia mixta de áreas fuentes compuestas por rocas metamórficas de alto, medio y bajo grado (gneises, esquistos y pizarras), no presentando indicios de aportes procedentes del macizo granítico de Guadarrama. En el Umbral de Ateca yen la unidad inferior, además, se pone de manifiesto la procedencia a partir de rocas sedimentarias areniscosas y pelíticas. La secuencia diagenética encontrada, con un modelo típico de flujos meteóricos, la escasa compactación química y los valores de la Ro = 0,5 nos ha permitido deducir para ellas una etapa de mesodiagénesis semimadura, según los criterios de Schmidt y McDonald (1979)

The Upper Oligocene of Montgat (Catalan Coastal Ranges, Spain): New age constrains to the western Mediterranean Basin opening

The Oligocene deposits of Montgat are integrated in a small outcrop made up of Cenozoic and Mesozoic rocks located in the Garraf-Montnegre horst, close to the major Barcelona fault. The Oligocene of Montgat consists of detrital sediments of continental origin mainly deposited in alluvial fan environments; these deposits are folded and affected by thrusts and strike-slip faults. They can be divided in two lithostratigraphic units separated by a minor southwest-directed thrust: (i) the Turó de Montgat Unit composed of litharenites and lithorudites with high contents of quartz, feldspar, plutonic and limestone rock fragments; and (ii) the Pla de la Concòrdia Unit composed of calcilitharenites and calcilithorudites with high contents of dolosparite and dolomicrite rock fragments. The petrological composition of both units indicates that sediments were derived from the erosion of Triassic (Buntsandstein, Muschelkalk and Keuper facies), Jurassic and Lower Cretaceous rocks (Barremian to Aptian in age). Stratigraphic and petrological data suggest that these units correspond to two coalescent alluvial fans with a source area located northwestwards in the adjoining Collserola and Montnegre inner areas. Micromammal fossils (Archaeomys sp.) found in a mudstone layer of the Pla de la Concòrdia Unit assign a Chattian age (Late Oligocene) to the studied materials. Thus, the Montgat deposits are the youngest dated deposits affected by the contractional deformation that led to the development of the Catalan Intraplate Chain. Taking into account that the oldest syn-rift deposits in the Catalan Coastal Ranges are Aquitanian in age, this allows to precise that the change from a compressive to an extensional regime in this area took place during latest Oligocene-earliest Aquitanian times. This age indicates that the onset of crustal extension related to the opening of the western Mediterranean Basin started in southern France during latest Eocene-early Oligocene and propagated southwestward, affecting the Catalan Coastal Ranges and the northeastern part of the Valencia trough during the latest Chattian-earliest Aquitanian times

Estratigrafía y petrología del subsuelo recuaternario del sector sw de la depresión de Barcelona (cadenas costeras catalanas, ne de Iberia)

[email protected] numerosas obras de Ingeniería Civil que se han realizado en los últimos años en la depresión de Barcelona (ampliación del aeropuerto, ampliación del metro y AVE fundamentalmente) han permitido recabar mucha información sobre el subsuelo de esta área. En este trabajo se caracterizan las distintas unidades de subsuelo precuaternarias que aparecen en los numerosos sondeos realizados recientemente en la zona SW de la depresión de Barcelona. Se ha identificado un sustrato triásico formado por areniscas del Buntsandstein y dos unidades de edad Miocena, una basal de carácter continental y otra superior depositada en un ambiente marino. Todas estas unidades fueron fracturadas debido a una tectónica extensiva y, posteriormente, fueron fosilizadas en primer lugar por los sedimentos del Plioceno, que recubren la superficie de erosión messiniense, y finalmente, por el Cuaternario. El análisis de las distintas unidades permite obtener datos sobre la evolución paleogeográfica y tectónica de la depresión de Barcelona durante el Mioceno y el Plioceno.Current building of civil Engineering infrastructures in the Barcelona plain and Llobregat delta (mainly metro and airport extension and high speed train) is providing new geological subsurface data to build better geologic models and understand the basin evolution. This work focuses on the pre-Quaternary units observed in cores. Based on petrographic analyses combined when it was possible with paleontological studies, we identified the lower Triassic Buntsandstein sandstone facies and Miocene continental and marine facies which appear compartmentalized due to extensive deformation. After this extensive episode, Pliocene and Quaternary sediments, which were deposited after the development of successive erosive surfaces, overlay the Triassic and Miocene units. The identification of these units enabled one to improve the interpretation of the tectonic and paleogeographic evolution of the Barcelona plain

Soft-sediment deformation structures interpreted as seismites in lacustrine sediments of the Prebetic Zone, SE Spain, and their potential use as indicators of earthquake magnitudes during the Late Miocene

Lacustrine formations of Late Miocene age in the Prebetic area, SE Spain, show several types of deformational structures that are interpreted as seismites. They are present in both marginal and deep lacustrine facies. Seismites formed in marginal lake environments comprise sand dikes, pillows and intruded and fractured gravels. In deep lacustrine facies, the seismites are represented by pseudonodules, mushroom-like silts protruding into laminites, mixed layers, disturbed varved lamination and loop bedding. The measured orientations of these structures are consistent with the orientations of the main faults limiting the basins, showing that their origin is clearly related to the tectonic stress field that prevailed in the region during the Late Miocene. The magnitudes of the earthquakes that deformed the sediments have been estimated after published data from both ancient and recent lake deposits accumulated in tectonic active regions elsewhere. A rank of earthquake magnitudes with two end-members, i.e. the lowest magnitudes recorded by loop bedding in laminites and the highest magnitudes represented by intruded and fractured gravels, is proposed

Geology of the Cerro Quema Au-Cu deposit (Azuero Peninsula, Panama)

The Cerro Quema district, located on the Azuero Peninsula, Panama, is part of a large regional hydrothermal system controlled by regional faults striking broadly E-W, developed within the Río Quema Formation. This formation is composed of volcanic, sedimentary and volcano-sedimentary rocks indicating a submarine depositional environment, corresponding to the fore-arc basin of a Cretaceous–Paleogene volcanic arc. The structures observed in the area and their tectono-stratigraphic relationship with the surrounding formations suggest a compressive and/or transpressive tectonic regime, at least during Late Cretaceous–Oligocene times. The igneous rocks of the Río Quema Formation plot within the calc-alkaline field with trace and rare earth element (REE) patterns of volcanic arc affinity. This volcanic arc developed on the Caribbean large igneous province during subduction of the Farallon Plate. Mineralization consists of disseminations of pyrite and enargite as well as a stockwork of pyrite and barite with minor sphalerite, galena and chalcopyrite, hosted by a subaqueous dacitic lava dome of the Río Quema Formation. Gold is present as submicroscopic grains and associated with pyrite as invisible gold. A hydrothermal alteration pattern with a core of advanced argillic alteration (vuggy silica with alunite, dickite, pyrite and enargite) and an outer zone of argillic alteration (kaolinite, smectite and illite) has been observed. Supergene oxidation overprinted the hydrothermal alteration resulting in a thick cap of residual silica and iron oxides. The ore minerals, the alteration pattern and the tectono-volcanic environment of Cerro Quema are consistent with a high sulfidation epithermal system developed in the Azuero peninsula during pre-Oligocene time

Estilolitos en carbonatos de plataforma del Cretácico Inferior: efecto como barreras y conductos en la circulación de fluidos diagenéticos

Los estilolitos y redes de estilolitos pueden jugar un papel importante en la evolución diagenética de rocas carbonatadas, hecho que ha suscitado un amplio debate durante los últimos años (Humphrey et al., 2019). Esta presentación tiene como objetivo la discusión del papel que juegan los estilolitos paralelos a la estratificación en la formación y distribución de dolo- mías de reemplazamiento y posterior evolución diagenética de las calizas de la Formación Benassal (Cretácico Inferior) de la Cuenca del Maestrat (Cordillera Ibérica oriental). Los resultados muestran que los estilolitos y las redes de estilolitos jugaron un papel fundamental en la formación de las dolomías y su posterior alteración hidrotermal. Durante el estadio de dolomitización (Cretácico medio), los estilolitos paralelos a la estratificación actuaron como barreras para los fluidos dolomitizantes y, por lo tanto, controlaron la componente lateral de circulación de fluidos y la distribución estratigráfica de las dolomías. Durante el estadio post-reemplazamiento (Cretácico Superior), algunos estilolitos actuaron como conductos de fluidos hidrotermales a sobrepresión que causaron corrosión y facilitaron la circulación posterior de fluidos mineralizantes. Como resultado aumentó la porosidad, y seguramente también la permeabilidad, asociada a estos estilolitos (Martín-Martín et al., 2018)

Exploring the response of a key Mediterranean gorgonian to heat stress across biological and spatial scales

Understanding the factors and processes that shape intra-specific sensitivity to heat stress is fundamental to better predicting the vulnerability of benthic species to climate change. Here, we investigate the response of a habitat-forming Mediterranean octocoral, the red gorgonian Paramuricea clavata (Risso, 1826) to thermal stress at multiple biological and geographical scales. Samples from eleven P. clavata populations inhabiting four localities separated by hundreds to more than 1500 km of coast and with contrasting thermal histories were exposed to a critical temperature threshold (25 degrees C) in a common garden experiment in aquaria. Ten of the 11 populations lacked thermotolerance to the experimental conditions provided (25 days at 25 degrees C), with 100% or almost 100% colony mortality by the end of the experiment. Furthermore, we found no significant association between local average thermal regimes nor recent thermal history (i.e., local water temperatures in the 3 months prior to the experiment) and population thermotolerance. Overall, our results suggest that local adaptation and/or acclimation to warmer conditions have a limited role in the response of P. clavata to thermal stress. The study also confirms the sensitivity of this species to warm temperatures across its distributional range and questions its adaptive capacity under ocean warming conditions. However, important inter-individual variation in thermotolerance was found within populations, particularly those exposed to the most severe prior marine heatwaves. These observations suggest that P. clavata could harbor adaptive potential to future warming acting on standing genetic variation (i.e., divergent selection) and/or environmentally-induced phenotypic variation (i.e., intra- and/or intergenerational plasticity).European Commission SEP-210597628- FutureMARES, MCIU/AEI/FEDER RTI2018-095346-BI00, Spanish government through the `Severo Ochoa Centre of Excellence' accreditation CEX2019-000928-S , Interreg Med Programme 5216|5MED18_3.2_M23_007, 1MED15_3.2_M2_ 337, Spanish Government FPU15/05457, Fundacao para a Ciencia e a Tecnologia (FCT) LA/P/0101/2020 , DivRestore/0013/2020, Marine Conservation research group 2017 SGR 1521, postdoctoral fellowship of project HABMAR - European Maritime and Fisheries Fund of the Operational Program MAR 2020 for Portugal MAR-01.04.02-FEAMP-0018info:eu-repo/semantics/publishedVersio