Indicios de impacto extraterrestre: su relación con la extinción de los dinosaurios

Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Análisis isotópicos (δ13C y δ18OCO3) en fósiles del Paleoceno basal de la Formación Tremp (Lleida): Implicaciones paleoambientales

Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Composition of clastic sediments in the Somosaguas area (middle Miocene, Madrid Basin): insights into provenance and palaeoclimate

[EN] The western area of the Cenozoic Madrid Basin has not been adequately studied. This, combined with the high homogeneity of detrital facies makes the stratigraphic correlation with other areas of the basin rather difficult. Consequently, only a detailed characterization of different study zones can allow subsequent correlation over this area. Over the last years there have been discovered several vertebrate fossil sites in this area that allow the dating of the sediments which host the fossil remains and provide data about palaeoclimatic trends. In this paper we present the results of the light minerals petrographic analysis carried out in one of these sites (Somosaguas paleontological site). Previous palaeontological and isotopic studies in this site indicate a climate event of cooling and rising aridity that has been described globally for the period after the Miocene Climatic Optimum. The petrographic data and indices presented here corroborate this trend towards a more arid climate through the Somosaguas sedimentary succession. Besides we study the grades of alteration of plagioclase grains as a proxy in the evaluation of palaeoclimatic variations. The increase towards the top of the succession of less altered plagioclase grains suggests a decrease in precipitations and thus more aridity. Part of the quartz and K-feldspar grains display several features like embayments and alterations pointing to palaeosoils formation and reworking processes. These characteristics and other observations suggest several sedimentary pulses in a geotectonic setting of “basement uplift” and a mixed lithological provenance for the Somosaguas deposits (granites, gneisses and minor quantities of low-grade metamorphic rocks).[ES] La zona occidental de la cuenca de Madrid no ha sido adecuadamente estudiada. Esto, combinado con la alta homogeneidad de facies detríticas dificulta la correlación estratigráfica con otras áreas de la cuenca. En consecuencia, sólo una caracterización detallada de diferentes zonas de estudio puede permitir posteriores trabajos de correlación regional. En los últimos años se han descubierto varios yacimientos de fósiles de vertebrados en esta área que permiten la datación de los sedimentos que albergan estos restos y proporcionan datos paleoclimáticos. En este trabajo se presentan los resultados de los análisis composicionales de minerales ligeros realizados en uno de estos yacimientos (yacimiento paleontológico de Somosaguas). Estudios paleontológicos e isotópicos previos en este yacimiento registran un evento climático de enfriamiento y aumento de la aridez que se ha descrito a nivel mundial para el período posterior al Óptimo Climático del Mioceno. Los datos e índices petrográficos presentados en este trabajo corroboran la tendencia hacia un clima más árido a lo largo de la sucesión sedimentaria de Somosaguas. Además, se estudian los grados de alteración de los granos de plagioclasa como proxy en la evaluación de variaciones paleoclimáticas. El aumento hacia la parte superior de la sucesión de plagioclasas poco alteradas sugiere una disminución de las precipitaciones y por tanto mayor aridez. Parte de los granos de cuarzo y de feldespato muestran golfos de corrosión o alteraciones que indican procesos de formación de paleosuelos y de retrabajamiento. Estas características junto a otras observaciones sugieren varios pulsos sedimentarios en un entorno geotectónico de “basamento elevado” y una procedencia litológica mixta (granito, gneis y rocas metamórficas de bajo grado).MINECO/CGL2008-01648MINECO/CGL2011-22709MINECO/CGL2009/09000Peer reviewe

Eggshell sites from the Cretaceous–Tertiary transition in south-central Pyrenees (Spain)

Near one hundred fossil sites containing dinosaur and avian eggs and eggshells have been recorded from coastal and non-marine deposits of late Cretaceous to late Paleocene age in South-central Pyrenees. Five eggsite types have been distinguished, three of them with autochthonous and two with allochthonous assemblages. The egg-bearing sediments consist in marine sandstones from the Aren Formation, and coastal and non-marine red beds from the Tremp Formation. Inferred nesting paleoenvironments range from sand beaches and strand plain at the seashore (Aren Sandstone sites), to tidal mud-flats in lagoonal margins (La Posa Grey Marls, lower Member of the Tremp Formation), and perilagoonal, estuarine and alluvial flood plains (bioturbated siltstones, variegated claystones, sandstones and conglomerates of the Tremp red beds). About thirty ootaxa, mainly from tubospherulitic, prismatic and ratite morphotypes have been observed, which greately overpass the dinosaur and avian diversity deduced from bones. These sites indicate a nest-fidelity reproductive behaviour for Pyrenean dinosaurs and birds. A decrease in abundance and diversity is recorded from late Campanian to Maastrichtian times, while a recovery occurs in late Paleocene

Estratigrafía del Cretácico Superior en las cabezeras de los Valles de Ansó y Roncal (Pirineo Occidental)

Se estudian tres columnas estratigráficas del Cretácico superior situadas en el Soum de Léche, Collado de Petrechema y Collado de Petraficha. Abarcan desde el Cenomanense al Maestrichtiense y en ellas se describe su litología y contenido en fósiles a partir del estudio de láminas delgadas. Discordante sobre el Paleozóico se sitúa un tramo de areniscas azóicas que, por su composición, se asemejan a la Fm. Arenas de Utrillas (Albense-Cenomanense inf.). El Cenomanense está representado por calizas y calizas arenosas y arcillosas; presenta un reducido espesor (1 a 3 m) y contiene principalmente Prealveolina y Daxia: El Turonense-Coniaciense, con menos de 5 m, está constituido por biomicritas y se ha caracterizado por la presencia de "Rotalina", Tritaxia y Pithonella. El Santoniense constituye la formación más importante, -conocida como «caliza de los cañones»- con un espesor que llega a superar los 300 m. Se trata de calcarenitas con intracIastos y pellets, con abundante contenido en microfósiles, entre los que destacan Dictyopsella, Dicyclina, Cuneolina, Martiguesia y en la parte superior Lacazina. El Campaniense, con unos 55 m, comienza por calizas con nódulos de sílex o areniscas finas muy calcáreas con Monolepidorbis, a las que siguen calcilutitas arcillosas con Globotruncana y Pithonella. El Maestrichtiense comienza por calizas arcillosas con esquistosidad que contienen Globotruncana, Navarella y Rugoglobigerina, seguidas por una serie turbidítica margoso-areniscosa. Se pone de manifiesto la posible existencia de un hiato entre el Turonense y Coniacense. Los niveles del Albense-Cenomanense inf. presentan una disminución del tamaño de grano hacia el sur. La transgresión cenomanense instaura un régimen de ambiente litoral, que en el Turonense y/o Coniacense se mantiene, evolucionando a un medio de plataforma, posiblemente semiabierta, en el sector meridional. El Santoniense se ha depositado en un medio de plataforma interna carbonática con episodios de carácter arrecifal. Durante el Campaniense y parte del Maestrichtiense el medio es de plataforma externa dando paso a un medio turbidítico. Los nódulos de sílex que presenta el Campaniense en el sector septentrional pasan a silicificaciones dispersas en el sector meridional, aumentando en el mismo sentido la esquistosidad. La recristalización es más manifiesta en los tramos altos del Santoniense del sector meridional. Se muestra también la distribución estratigráfica de los principales micro fósiles determinados en la zona

The microbiology of sepsis is more than the application of new technologies in diagnosis

Sepsis; New technologies; DiagnosisSèpsia; Noves tecnologies; DiagnòsticSepsis; Nuevas tecnologías; DiagnósticoAdequate and rapid microbiological diagnosis of sepsis is essential for correct treatment, having a direct impact on patient prognosis. Clinical Microbiology Services must adapt fast circuits that allow prioritizing and individualizing the diagnosis of these patients. The measures adopted should not be based solely on the incorporation of new technologies but, to a large extent, on ensuring accurately collection and processing of samples, avoiding unnecessary losses of time in processing and ensuring that the information derived from this process adequately reaches the prescribing physician

A multi-proxy geochemical investigation of the early Paleocene (Danian) continental palaeoclimate at the Fontllonga-3 site (South Central Pyrenees, Spain)

Chronologically well constrained non-marine deposits across the Cretaceous–Tertiary boundary (KTb) are exceptionally rare. The Fontllonga section (Tremp Formation, South Central Pyrenees, Lleida, Spain) constitutes one of these rare global records. Stable isotope (δ18OCO3 and δ13C) analyses have been performed on the carbonate fraction of 29 samples from diverse skeletal micro-remains (charophyte gyrogonites, gastropod shells, ostracod valves and isolated skeletal remains of lepisosteids and pycnodonts) from the earliest Danian site, Fontllonga-3. A mean Ba/Ca water palaeotemperature of 28.0 ± 6.7 °C has been obtained from the ganoine of 25 lepisosteid scales. This mean palaeotemperature is comparable with the temperature tolerance range for extant relatives of fossil osteoglossiform fish found at Fontllonga-3, which require a temperature range of 24°–35 °C (mean annual temperature 27–30 °C) to survive. Using the temperature range provided by the Ba/Ca palaeothermometer (21.3–34.7 °C), it is possible to determine δ18Owater values from the isotopic content of charophyte gyrogonites, gastropod shells, ostracod valves and fish remains (mean δ18OCO3 = − 5.00 ‰, σ = 0.21). δ18Owater values of between − 4.01 and − 0.95‰ (VSMOW) are calculated, which, when combined with (La/Yb)N versus (La/Sm)N plots, are in good agreement with the sedimentary interpretation of the site as an estuarine environment. Based upon a comparison with modern day meteorical conditions these isotopic values are relatively high for subtropical freshwaters, suggesting a low precipitation rate (amount effect, high evaporation rate and/or long residence time). When combined with other isotopic, palaeobotanical and mineralogical studies carried out in the Pyrenean and Tethys realms this first geochemical study of an early Paleocene site is consistent with there being a subtropical seasonally dry climate in the South Central Pyrenees at this time

Analysis of the geochemical variability in lepisosteid scales from the Fontllonga-3 site (early Danian, Tremp Formation, South Central Pyrenees, Spain): Implications for palaeoenvironmental studies

Rare Earth Element (REE), Ba/Ca, Sr/Ca and δ18OPO4 analyses have been performed on the ganoine and isopedine of different types of isolated scales (anterior, middle, posterior flank scales and dorsal body margin scales) from juvenile lepisosteids from the Fontllonga-3 site (early Danian, Tremp Formation, South-Central Pyrenees, Spain) with the aim of detecting the most suitable kind of scale to be used in palaeoclimate studies. The REE flat-shape patterns obtained in lepisosteid scales from Fontllonga-3 are indicative of the absence of late stage diagenesis and recrystallization and have confirmed the identification of the palaeoenvironment where the Fontllonga-3 lepisosteids inhabited to be that of an estuary. The Ba/Ca palaeothermometer shows that posterior flank scales record on average 4.52 °C (ganoine) and 3.49 °C (isopedine) higher temperatures when compared to middle flank scales, which may be related to the fact that posterior flank scales grow preferentially during the warm season, whilst middle flank scales, which have the greatest number of layers of ganoine per unit of time and grow all year round, record a greater amplitude with respect to palaeoenvironmental and palaeoclimatic variations. Temperature values obtained from anterior flank scales follow a pattern similar to that showed by middle flank scales, whilst temperature values provided by dorsal scales resemble the pattern furnished by posterior flank scales. The same relationship between scale position and temperature but to a lesser degree (1.48 °C) is also evident in the calculated δ18OPO4 temperatures. The Ba/Ca palaeothermometer was applied by considering Ba/Ca ratios of the water for different types of environments and it has been found out that a ratio similar to that of marine waters yielded the best approximation to δ18OPO4 temperatures (29.82 ± 3.76 °C). The mean Ba/Ca temperature value obtained from the analysis of all the ganoine samples (26.96 ± 5.72 °C) is also consistent with the temperature of the water in which extant relatives of osteoglossiform fish, whose remains have been found in Fontllonga-3 along with lepisosteid remains, inhabit nowadays (24–40 °C, with mean values of 27 to 32 °C). The mean Ba/Ca temperature values furnished by the isopedine are lower than that obtained on the ganoine which may be due to minor diagenetic alteration. On account of these results, it is recommended that a distinction should be made between different types of scales as this could provide information concerning the summer growth temperature (posterior flank scales) as well as the annual temperature range (middle flank scales). Furthermore, it is recommended that ganoine be used in all studies as it appears to be the most resistant tissue in lepisosteid scales to diagenetic alteration

Nuevos datos paleontológicos del Pleistoceno en el Valle del Manzanares (Madrid, España): Los micromamíferos del yacimiento del Arenero de Arriaga

The micromammals from the archaeological site of the Arenero de Arriaga from the Manzanares Valley are here described. They are the Soricomorpha: Crocidura sp. and Talpa sp., the Rodentia: Eliomys quercinus quercinus, Apodemus sp., Microtus brecciensis, Microtus arvalis, Microtus duodecimcostatus and Arvicola aff. sapidus, and the Lagomorpha: Oryctolagus cuniculus. The faunal association and the evolutionary state of Microtus brecciensis and Arvicola aff. sapidus, suggest an age of the end of the Middle Pleistocene. It also indicates the existence of different biotopes: riparian, moist and dry meadows, and forest, and a temperate climate similar to the present-day climate of the Meseta.Se describe la asociación de micromamíferos del yacimiento achelense del Arenero de Arriaga del valle del Manzanares constituida por los soricomorfos: Crocidura sp. y Talpa sp., los roedores: Eliomys quercinus quercinus, Apodemus sp., Microtus brecciensis, Microtus arvalis, Microtus duodecimcostatus y Arvicola aff. sapidus, y el lagomorfo: Oryctolagus cuniculus. La asociación faunística y el estadio evolutivo de Microtus brecciensis y Arvicola aff. sapidus, indican una edad del final del Pleistoceno Medio. La asociación de micromamíferos sugiere la existencia de varios biotopos representados: ripícola, praderas húmedas y secas, y bosque, y un clima templado similar al actual de la Meseta

[The finding of Dacryloidires attoi (Geinitz, 1849) in the Arén Sandstone Upper Cretaceous, southern Pyrenees)]

Número extraordinario. Homenaje al Prof. J. Truyols.En el Cretácico Superior de la Arenisca de Arén (cuenca surpirenaica) se registran pistas fósiles atribuidas a Dactyloidites ottoi (Geinitz, 1849) en sedimentos marinos de estuario con influencia de mareas. Las pistas en forma de roseta tienen 12-20 radios rectos o asimétricamente ramificados, con una sección constante de unos 5 mm, que cubren unos 200º de círculo. Este icnotaxón, producido por un animal sedimentívoro desconocido, ha sido también encon trado en facies similares en sedimentos del Cretácico Superi or en Alemania, Japón y Groenlandia, y en areniscas del Neógeno de Borneo, España y Jamaica. Los hallazgos apuntan hacia un organismo productor habitante de medios de estuario inferior en climas tropicales.Trace fossils attributed to Dactyloidites ottoi (Geinitz, 1849) have been found in estuarine, tide-influenced deposits of the Upper Cretaceous Arén Sandstone (South-Central Pyrenees, Spain). The rosette-shaped traces have 12-20 straight or asymmetrically branched radial elements, with a constant width of about 5 mm, covering around 200 degrees of a circle. This ichnotaxon, which was produced by an unknown sedimentivorous animal, has al so been found in similar facies in Upper Cretaceous sediments from Germany, Japan and Greenland, and Neogene sandstones from Borneo, Spain and Jamaica. The findings point to a tracemaker living in a lower estuarine environment with a tropical climate.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEEspaña. Dirección General de Investigación Científica y Técnicapu