300 research outputs found
Sedimentology and cyclostratigraphy of the Barahona Formation (Lower Jurassic) in the Aragonese Branch of the Iberian Range
A detailed bed-by-bed sedimentological and cyclostratigraphic
characterization of the Barahona Formation has been carried out in two
representative outcrops in the Aragonese Branch of the Iberian Range, in
order to characterize the sedimentary environment and evaluate the factors
controlling the sedimentation during the upper Pliensbachian in the Iberian
Basin. Facies range from proximal mid-ramp bioclastic packstones, distal
mid-ramp bioclastic wackestones and mudstones, to proximal outer-ramp
marly limestones and marls. Sequence analysis indicates the presence of
twelve metre-thick high-order sequences, grouped in four longer-term
sequences, which have been interpreted in terms of relative sea-level
variations controlled by climatic changes in the bands of short- and longterm
eccentricity cycles. At the longer scale, the studied unit records the
regressive episode of the late Pliensbachian, and probably the initial
deepening of the Toarcian cycleSe realiza la caracterización sedimentológica y cicloestratigráfica capa a
capa de la Formación Barahona en dos afloramientos representativos de la
Rama Aragonesa de la Cordillera Ibérica, con objeto de proponer un modelo
de sedimentación y evaluar los factores que controlaron la sedimentación durante
el Pliensbaquiense superior en la Cuenca Ibérica. Las facies representan
una rampa carbonatada dominada por tormentas, desde rampa media
proximal (packstones bioclásticos) y media distal (wackestones y mudstones
bioclásticos) a rampa externa proximal (margocalizas y margas). El análisis
secuencial constata la presencia de doce secuencias de alto orden de potencia
métrica, agrupadas en cuatro secuencias de mayor duración temporal.
Las secuencias se atribuyen a variaciones relativas del nivel del mar inducidas
por cambios climáticos asociados a ciclos orbitales de excentricidad
de corto y largo término.A mayor escala, la Fm. Barahona registra el evento
regresivo del Pliensbaquiense superior y, en su parte terminal, probablemente
el inicio de la profundización del ciclo toarciens
Un poema cretense de Yorgos Seferis
La concesión en 1963 del Premio Nobel de Literatura a Yorgos Seferis
supuso personalmente para mí el primer contacto con una realidad hasta
entonces incomprensiblemente desconocida: el griego seguía estando vivo y
además tenía sus poetas. Por aquellos años, ni siquiera a quienes estudiábamos
Letras en el Bachillerato se nos había hablado de la transformación
y pervivencia de la lengua griega moderna. Por eso, para algunos de
entre los que entonces pensábamos encaminar nuestros estudios hacia la
Filología Clásica, la lengua y literatura neogriegas poseían un atractivo especial,
mezcla de preocupación exótica y cómplice por algo tenido desde
arriba como último eslabón degradado y tardío, incapaz de competir con la
perenne lozanía de lo clásico.Peer reviewe
A la búsqueda del concepto de diplomacia bizantina
In popular sense the word "Byzantine" is synonimous with deviousness anddipomatic intrigue, but the Byzantine diplomacy was in fact very complex and pragmatic. The aim of this paper is to contribute precisely to the research of Byzantine diplomacy, a field still lacking a comprehensive and systematic investigation. We intend here to survey the notion of Byzantine diplomacy taking into account the geopolitical context of the empire. From the specific particularities in the time and the space we try to explain the overall pattern of the foreign policy in Byzantium; we introduce distinctions into 'foreign affairs' and 'diplomacy' and we examine the changing diplomatic practices, always subordinate to a defensive
Arrecifes de coral y concentración de dióxido de carbono: Un ejemplo en la didáctica sobre Cambio Climático
Las tribulaciones de un ortodoxo ruso "in partibus infidelium"
El relato de Afanasi Nikitin Viaje allende los tres mares no es un libro de viajes al uso. Este trabajo estudia la característica más importante de este texto: la creación de un original «lenguaje secreto», mezcla de persa, turco y árabe transcrito en alfabeto cirílico. Mediante este recurso, el autor, expresa sus dudas acerca de la fe religiosa que teme haber perdido después de pasar seis años en tierras de infieles, Persia, Golfo Pérsico y la India sin ningún contacto con cristianos.The Afanasij Nikitin's Journey beyond the Tree Seas is not a usual travel book. This paper focuses the most important feature of the Nikitin's text: the creation of an original 'secret language', mixing of Persian, Turkish and Arabic transcribed in Cyrillic alphabet and embedded in the Russian text. Through this resource, the author, expresses his doubts about the religious faith that feared losing after spending six years in the land of infidels, Persia, Persian Gulf, and the India without any contact with Christians
Factors controlling the sedimentary evolution of the Kimmeridgian ramp in the north Iberian Basin (NE Spain)
The aim of this paper is to summarize the present knowledge reached by the authors on the carbonate ramp which developed in the iberian basin during Kimmeridgian times. Our results were obtained from a combined field analysis and computer modelling carried out in the north Iberian Chain (NE Spain). Extensive field analysis in the Ricia area (Zaragoza, NE Spain), resulted in a detailed mapping of the transition from inner to outerramp facies on this carbonate rampo Three facies belts may be distinguished in this rampo The outer ramp facies consists of marls and mudstones rhythmic facies. The inner ramp facies, located aboye fair-weather wave base, are dominated by coral patch reef growing. The middle ramp facies are represented by marls and micrites bearing skeletal and oolitic tempestite levels which sharply grade into high-amplitude o'olitic sandwave. Factors such as resedimentation by storms, carbonate production and relative variation of sea level acting in the Kimmeridgian ramp are also quantiphied and discussed. Most of the mud accumulated in outer-ramp areas was produced in the coral «carbonate factory» located in inner areas. Off-shore resedimentation by storm was the main agent of basinward transport of this mudo The deduced accommodation curve consists of three elements: a linear rise which satisfactorily matches the normal subsidence figures observed in intracratonic basins; a third-order cycle, that may have a regional cause and higher order cycles in the Milanckovich band, that may be eustatic in origin.La sedimentación en la cuenca ibérica septentrional durante el Kimmeridgiense tuvo lugar en una extensa rampa carbonatada de bajo ángulo. Las facies de rampa externa, acumuladas por debajo del nivel de base del oleaje debido a tormentas (i.e., C. 50 to 80 m de profundidad), están formadas por una ritmita de margas y calizas (i.e., Fm Loriguilla). Las facies de rampa interna, localizadas por encima del nivel de base del oleaje de buen tiempo (i.e., hasta 10 m de profundidad), están dominadas por bioconstrucciones de corales (i.e .. Fm Torrecilla). Las facies de rampa media están representadas por margas y micritas con niveles de tempestitas bioclásticas y oolíticas que pasan lateral y verticalmente a sandwaves oolíticos de gran amplitud (i.e., Mb. Ricia). La modelización por ordenador ha permitido cuantificar algunos aspectos de esta rampa. Así, la distancia de resedimentación mar adentro del sedimento de grano fino producido en las zonas internas de la rampa, por el efecto de tormentas, puede ser de hasta 40 Km. La producción de carbonato oscilaría entre 8 y 2 cm/l.000 años. en función de la profundidad. Por otra parte, la curva de la variación de la acomodación deducida para el Kimmeridgiense está compuesta por tres elementos: un ascenso lineal de 4 cm/l.000 años. un ciclo de tercer orden de baja amplitud y ciclos de mayor orden. de 20.000 y 100.000 años respectivamente. Tanto el ascenso lineal como el ciclo de tercer orden se han relacionado con causas regionales, mientras que los ciclos de mayor orden se encuentran en la banda de Milanckovich y pueden ser por tanto de origen eustático
El erotismo literario como testimonio del cambio de los valores morales en Bizancio en los siglos XI-XII
Examination of the transformation of the values‘ scale in the Byzantine society during the 11th and 12th centuries, through the introduction of erotism in literature. The treatment of this issue and the erotic language are studied in various writers and genres of the above mentioned period.Examen de la transformación de la escala de valores en la sociedad bizantina de los siglos XI-XII a través de la entrada en la literatura del erotismo. Se estudia el tratamiento del tema y lenguaje eróticos en diversos autores y géneros del período señalado
A mud-dominated coastal plain to lagoon with emerged carbonate mudbanks: The imprint of low-amplitude sea level cycles (mid-Upper Cretaceous, South Iberian Ramp)
The middle Santonian-lower Campanian carbonate-mud dominated succession deposited in the northeastern margin of the South Iberian Ramp (La Cañadilla Fm, NE Spain) shows a complex set of interfingered facies developed in a low-energy and low-gradient shallow-marine to coastal environment. Three facies belts characterize the environment reconstructed in this work: (1) a low-energy shallow marine lagoon dominated by radiolitid rudist limestones and miliolid-rich facies with variable carbonate-mud content; (2) a transitional belt with a patchy distribution of ponds and mudbanks. This belt mostly consists of miliolid-rich limestones with variable amount of fenestral porosity, which are interfingered with charophytes and gastropod marls and limestones usually mixed with miliolids; (3) a coastal plain with strong freshwater influence characterized by the sedimentation of marls and limestones with charophytes, gastropods and root traces and intraclastic/black pebble limestones. The studied succession is arranged in high-frequency sequences, including meter-scale parasequences bounded by widespread flooding surfaces, which stack in five larger-scale shallowing-upward sequences (6–20 m thick). The time calibration of these sequences obtained from strontium isotopes and biostratigraphic data (benthic foraminifera) suggests a major control in the sedimentation by climate-driven low-amplitude sea level oscillations formed in tune with the long- and short-eccentricity orbital cycles. Cyclic sea level rises controlled the existence of widespread flooding events in the low-gradient carbonate ramp at the onset of parasequences, which in the studied marginal areas of the South Iberian Ramp were mostly sourced from the southern Tethyan realm. Therefore, the La Cañadilla Fm provides an example of a complex shallow marine to coastal system giving rise to a mosaic distribution of carbonate-mud dominated facies, with sedimentation mostly influenced by external factors resulting in a well-defined stratigraphic architecture. The similarities with modern analogous systems such as the Ten Thousand Islands of the Florida Bay are discussed in this paper. © 2022 Elsevier B.V
A New Calcareous Nannofossil Record from the Lower Jurassic of Kermanshah, Western Iran: Implications for Biostratigraphy and Evolutionary Reconstructions
Calcareous nannofossils are used here for the first time in order to establish a precise biostratigraphic framework for the Kermanshah Radiolarite Formation, an outcropping in Western Iran. The new data presented here challenge the previous tentative age interpretations (Pliensbachian to early Toarcian) based upon radiolarians. Calcareous nannofossil assemblages and events unequivocally indicated that the pelagic limestones and marls are late Sinemurian in age (NJT 3b nannofossil subzone), and that these are thrusted over shales and cherts dated as uppermost Sinemurian (NJT 3b-c nannofossil subzone) and lowermost Pliensbachian (NJT 4 nannofossil zone). This result leads not only to reconsideration of the age of the radiolarite formations, which are widespread in the Zagros orogenic system, but also a better understanding of the stratigraphic relationships between the various lithological units known in the area. Besides these new stratigraphic inferences, the calcareous nannofossil assemblages of the uppermost Sinemurian– lowermost Pliensbachian successions revealed the common presence of new morphologies of the Mitrolithus genus, never described before. These findings allow for the description of three new species, M. montgolfieri, M. pseudonannoconus, and M. tethysiensis, and reveal the existence of homeomorphy between the spine structure of conical Lower Jurassic coccoliths and the widespread Cretaceous nannoconids. © 2022 by the authors. Licensee MDPI, Basel, Switzerland
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