Oncolitos continentales en el Campaniense superior de la Cuenca de Montalbán (Allueva Fm, Cordillera Ibérica)

This study focuses on the analysis of the oncolites found in the Allueva Fm, an uppermost Cretaceous (middle-upper Campanian) alluvial unit deposited during the initial stages of development of the compressional Montalbán Subbasin (Iberian Chain). Successive oncolitic levels are found in the upper part of the formation, wes-twards the locality of Fonfría (northern Teruel province). There, the 45 m-thick succession logged consists of an association of oncolitic limestones, mudstones and marlstones. Oncoid sampling has been done for petrographic description and isotopic analysis. Oncoids are accumulated in up to 1 m-thick lenticular levels, and show spheri-cal to elliptical shapes with sizes ranging between 1 and 15 cm, the smallest being oncoids dominant. Oncoid lamination is concentri-cal with almost no irregularities (SS-C oncoids), indicating constant movement. A preliminary isotopic study performed of successive on-coid laminations is coherent with a fresh-water environment with sub-humid climatic conditionsEste estudio se centra en el análisis de niveles oncolíticos encontrados en la Formación Allueva, una unidad aluvial de edad Campaniense medio a superior depositada durante las etapas iniciales de desarrollo de la subcuenca compresiva de Montalbán (Cordillera Ibérica). La acumulación de oncoides se encuentra en la parte superior de la formación, y aflora hacia el oeste de la localidad de Fonfría (norte de la provincia de Teruel). Allí, la sucesión de 45 m de espesor consiste en una asociación de calizas oncolíticas, lutitas y margas. Se ha realizado un muestreo de los oncoides para su descripción petrográfica y análisis isotópico. Los oncoides se acumulan en capas lenticulares de hasta 1 m de espesor, y presentan formas esféricas a elípticas con tamaños que oscilan entre 1 y 15 cm, dominando los oncoides de menor tamaño. La laminación es concéntrica con casi ninguna irregularidad (oncoides SS-C), lo que indica condiciones de movimiento constante. Un estudio isotópico preliminar llevado a cabo en láminas sucesivas de oncoides es coherente con un ambiente de agua dulce bajo condiciones climáticas subhúmeda

From platform to basin to swell: orbital control on sedimentary sequences in the Oxfordian, Spain

Climatic, oceanographic and ecological changes that control the formation and deposition of sediment in shallow and deep depositional environments commonly occur with periodicities of a few 10 000 years. Consequently, in order to interpret sedimentary sequences in the geological past, high time resolution is required. This is best obtained by cyclostratigraphy. Three sections have been studied in the Oxfordian of north-eastern Spain: one represents a shallow, siliciclastic-carbonate platform with repetitive subaerial exposures, one an intraplatform basin with sponge bioherms, and one a swell where iron ooids and glauconite formed. The platform section displays a well-defined stacking pattern of depositional sequences; the deeper-water sections are well dated by ammonites. The correlation between the three sections is a best-fit solution integrating biostratigraphy, sequence stratigraphy and cyclostratigraphy. It is concluded that the small-scale depositional sequences formed in tune with the 100-ka orbital eccentricity cycle. An additional factor was differential subsidence that ruled basin morphology

Hedged Monte-Carlo: low variance derivative pricing with objective probabilities

We propose a new `hedged' Monte-Carlo (HMC) method to price financial derivatives, which allows to determine simultaneously the optimal hedge. The inclusion of the optimal hedging strategy allows one to reduce the financial risk associated with option trading, and for the very same reason reduces considerably the variance of our HMC scheme as compared to previous methods. The explicit accounting of the hedging cost naturally converts the objective probability into the `risk-neutral' one. This allows a consistent use of purely historical time series to price derivatives and obtain their residual risk. The method can be used to price a large class of exotic options, including those with path dependent and early exercise features.Comment: LaTeX, 10 pp, 3 eps figures (in text

Jurassic-Cretaceous transition units of north Maestrazgo (NE of Teruel)

Different shallow marine units from the Jurassic-Cretaceous transition in Iberian Chain are well exposed in the outcrops of Northern Maestrazgo (Teruel). This work tries to show with precision the correlation between the different units present in this zone, and the position of Jurassic-Cretaceous boundary. Based on biostratigraphic markers and sequential correlation, a modified lithostratigraphic chart is propose

Systematics of Lutetian larger foraminifera and magneto-biostratigraphy from the South Pyrenean Basin (Sierras Exteriores, Spain)

A systematic description of the Eocene larger foraminifera recorded in the South Pyrenean Basin (Sierras Exteriores) is presented herein. The large dataset provided in this work includes Nummulites and Alveolina species, along with a variety of other porcellaneous and hyaline taxa with lesser biostratigraphic relevance. Most of the larger foraminifera described in this work correspond to the Lutetian (SBZ13 to SBZ16 biozones) interval, but late Ypresian (SBZ11, Cuisian) and early Bartonian (SBZ17) shallow benthic zones have also been identified. A new species, Idalinaosquetaensis, is described. The systematic revision of middle to late Lutetian alveolines led to a reassessment of Alveolinafusiformis and the finding of two new precursor forms, described as Alveolina aff. fragilis and Alveolina aff. elongata. The new taxa fill in the gap existing so far in the middle to late Lutetian alveolinid biostratigraphy. Despite not being exclusive to SBZ16, these forms provide realiable biostratigraphic information in facies where Nummulites are not present. This realibility lies on the correlation of Nummulitesand Alveolina biostratigraphic markers in the same sections and their calibration to the global time scale through magnetostratigraphy. Magnetostratigraphic calibration of described taxa is provided, along with an update of the SBZ calibration to the Geological Time Scale (Gradstein et al., 2012).&nbsp

Geoloday for a large audience: key points for its organization

Geoloday is an outreach initiative at national level, coordinated by the Geological Society of Spain. It consists in a fieldtrip guided by teams of geologists, with as much excursions as Spanish provinces. We analyze the participation in the last six editions. This bring us to determine the optimum format of this event when there is a lot of people, that is, the organizers fixed in the stops while the public moves by walking from one stop to the other. Finally, we give a series of key points in terms of organization to deserve a qualified attention to a lot of participants. At the same time, these advices are useful in order that not only these latter but also the organizers enjoy GeolodayGeolodía es una iniciativa de divulgación de la Geología de ámbito nacional, coordinada por la Sociedad Geológica de España. Consiste en excursiones de campo guiadas por equipos de profesionales de la geología, con tantas excursiones como provincias españolas. Analizamos la asistencia de las seis últimas ediciones que tuvieron lugar desde 2010 y determinamos el formato óptimo de esa jornada cuando el número de asistentes es muy alto: organizadores fijos en las paradas con el público andando entre ellas. Terminamos dando una serie de claves en cuanto a organización para que la atención sea de calidad y que tanto los asistentes como los organizadores disfruten de Geolodí

Velocity fluctuations in forced Burgers turbulence

We propose a simple method to compute the velocity difference statistics in forced Burgers turbulence in any dimension. Within a reasonnable assumption concerning the nucleation and coalescence of shocks, we find in particular that the `left' tail of the distribution decays as an inverse square power, which is compatible with numerical data. Our results are compared to those of various recent approaches: instantons, operator product expansion, replicas.Comment: 10 pages latex, one postcript figur

Lateral facies changes in high-frequency, peritidal carbonate cycles (Sinemurian, Iberian Chain)

The sedimentary record of the high-frequency Sinemurian cycles originated in the shallow carbonate platform of the northern Iberian basin (NE Spain) show marked differences depending on the environment in which they developed. Vertical facies distribution in shallowing upward cycles with intertidal laminated caps has a great lateral homogeneity (more than 12 km across) with no significant variation. However, the cycles dominated by grainy facies, mostly formed in the open marine wave-agitated areas, show rapid lateral facies changes and irregular record of discontinuity surfaces. In this case, the number and distribution of the cycles defined in a single log cannot be representative of the entire platform area. Accordingly, the definition of cycles originated in these high-energy open platform areas should be based in the analysis of laterally continuous outcrop