The Upper Cretaceous succession in northern South America is significant because the related rock deposits are among the most prolific oil sources in the region. Although several geological studies ...have focussed on this period, we still have poor knowledge of the exact deposition time of the lithostratigraphic units. In this study, we constructed a chronostratigraphic framework based on U–Pb ages and time-calibrated carbon isotopic events to constrain the chronostratigraphy of the Upper Cretaceous formations. The carbon isotope curve of the La Luna-1 core allowed us to identify several oceanic anoxic events also identified in the stratotypes of the Upper Cretaceous formations. The La Luna-1 also preserves a complete record of ash beds, from which zircons were extracted for U–Pb dating. The stratigraphic distribution of the ash beds indicates a crucial influence of volcanic activity during the Late Cretaceous. Sedimentological descriptions and mineralogical analysis were used to establish the primary lithological differences between the units. The Upper Cretaceous formations can be categorised as mixed rocks comprising variable percentages of carbonates, quartz and clay minerals. They also show silicification and, to a lesser extent, dolomitisation and recrystallisation. The Salada, Pujamana, and Galembo formations range in age between the Cenomanian and Coniacian, whereas the overlying La Renta Formation spans from the Santonian to at least the middle Campanian. The top of the La Renta Formation corresponds to a regional disconformity that contacted the middle Campanian with the Maastrichtian.
•The Cretaceous was characterized by high burial rates of carbon in the form of carbonates and organic carbon, much of the latter forming a significant proportion of the hydrocarbon source rocks in many sedimentary basins around the world, including South America.•The late Cretaceous of northern South America preserves a very complete record of the oceanic anoxic events (OAEs) that have been reported globally.•The late Cretaceous was characterized by the occurrence of an important volcanic activity.•The La Luna Formation was deposited between the Cenomanian and Santonian and their former members (Salada, Pujamana, and Galembo) should be elevated to the category of formations.
The compositional, geochemical and petrophysical characterization of a stratigraphic section from the Coniacian-Campanian in the South of the Middle Magdalena Valley basin allowed identifying the ...potential of this area for unconventional shale reservoirs.
Siltstone facies composed of bio-mudstone with organic matter and micrite, and silty mudstone microfacies with foraminifera, showed the best conditions. Rock-Eval results showed a Type II Kerogen with TOC values that range between 2% and 4% and thermal maturity of 0.8% Ro, which demonstrates an optimal mat
urity level for liquid hydrocarbon generation of this section. Compositionally, the upper part is characterized by high quartz content, whereas the middle section has high calcite content enhancing the mechanical properties of the rock in the event of hydraulic fracturing. The petrophysical analysis indicated optimal values for intergranular porosity favoring hydrocarbon storage. Data integration indicated at least two intervals with high potential for shale oil within the sequence studied.
•Organic and inorganic characterization of a stratigraphic section from the Coniacian-Campanian in the MMV basin.•Integration of multiple techniques allowed identifying the potential for unconventional shale reservoirs.•Integration of multiple techniques allowed identifying the potential for unconventional shale reservoirs.
Cittarium pica is an endangered Caribbean gastropod of ecological and economic importance. In order to provide the basis for the aquaculture development and/or population management of this species, ...the relationships among its body size and physiological variables associated with the energetic balance were assessed. Individual measurements of rates of egestion (ER), ingestion (IR), absorption (AR), oxygen consumption (OCR), ammonia excretion (UR), mucus production (MR), absorption efficiency (AE) and scope for growth (SFG), were carried out on specimens between 0.01 and 12.07 g of dry weight of the soft parts (DW) under controlled laboratory conditions. Most of the variables showed positive potential relationships with the DW of the animals (ER mg h.sup.-1 = 1.51 DW.sup.0.37, IR mg h.sup.-1 = 4.13 DW.sup.0.32, AR = 2.56 DW.sup.0.30, OCR mL O.sub.2 h.sup.-1 = 0.38 DW.sup.074, UR microg NH.sub.4 -N h.sup.-1 = 19.17 DW.sup.0.78, MR mg h.sup.-1 = 1.28 DW.sup.0.14 and SFG = 36.92 DW.sup.0.22). AE did not show any relationship with this variable. The large snails had faster input and output of energy compared to the small specimens, also having proportionally greater energetic expenditures, mucus production, and energetic balance.
Some Onchocercidae nematodes such as
Pelecitus
are parasites of medical and veterinary importance. The adult stage of
Pelecitus
has been reported infecting birds, and the microfilaria has been ...associated to human blindness. However, in some of these cases, the nematode was incompletely identified at the species level due to the scarcity of morphological taxonomic keys and, also, to the lack of molecular diagnostic analysis. Here, we report a new
Pelecitus
species in a crested caracara (
Caracara cheriway
) producing a severe tenosynovitis and microfilarial dermatitis. It is also the first record of
Pelecitus
in an American bird of prey. Clinical and histopathological features are described, contributing towards our understanding of the pathogenesis of
Pelecitus
and the health and conservation of wild bird populations. Our study also provides new information on the molecular diagnosis of this parasite and highlights the potential role of wild birds as
Pelecitus
reservoirs, and health risk for humans and wildlife.
Fine-grained and mainly reddish color, compact and slightly breccious and vesicular pyrometamorphic rocks (natural clinker) are associated to the spontaneous combustion of coal seams of the Cerrejon ...Formation exploited by Carbones del Cerrejon Limited in La Guajira Peninsula (Caribbean Region of Colombia). These rocks constitute remaining inorganic materials derived from claystones, mudstones and sandstones originally associated with the coal and are essentially a complex mixture of various amorphous and crystalline inorganic constituents. In this paper, a petrographic characterization of natural clinker, as well as the application of the X-ray diffraction (Rietveld method) by mean of quantitative analysis of its mineral phases were carried out. The RIQAS program was used for the refinement of X ray powder diffraction profiles, analyzing the importance of using the correct isostructural models for each of the existing phases, which were obtained from the Inorganic Crystal Structure Database (ICSD). The results obtained in this investigation show that the Rietveld method can be used as a powerful tool in the quantitative analysis of phases in polycrystalline samples, which has been a traditional problem in geology. Key words: Rietveld method, Cerrejon, X-ray powder diffraction, natural clinker. Rocas pirometamorficas (clinker natural) de grano fino y coloracion principalmente rojiza, compactas, y ligeramente brechadas a vesiculares estan asociadas a la combustion espontanea de mantos de carbon de la Formacion Cerrejon explotados por Carbones del Cerrejon Limited en la peninsula de La Guajira (Region Caribe de Colombia). Estas rocas constituyen materiales inorganicos remanentes derivados de arcillolitas, limolitas y areniscas originalmente asociadas con carbon y son esencialmente una mezcla compleja de diferentes constituyentes inorganicos amorfos y cristalinos. En el presente trabajo, se llevo a cabo la caracterizacion petrografica del clinker natural, asi como la aplicacion de la difraccion de rayos-X de polvo (metodo de Rietveld) para el analisis cuantitativo de las fases minerales presentes de las rocas en estudio. El programa RIQAS fue utilizado para el refinamiento de perfiles de difraccion de rayos-X de polvo, analizando la importancia de utilizar los modelos isoestructurales adecuados para cada una de las fases presentes, los cuales se obtuvieron de la base de datos Inorganic Crystal Structure Database (ICSD). Los resultados obtenidos en la presente investigacion muestran que el metodo de Rietveld puede usarse como una poderosa herramienta en el analisis cuantitativo de fases en muestras policristalinas, lo cual ha sido un problema tradicional en el campo de las geociencias. Palabras clave: metodo de Rietveld, Cerrejon, difraccion de rayos X de polvo, clinker natural.
We present a new record of rattlesnake Crotalus scutulatus collected in the county of La Paz, Mexico, that confirms the presence of the species for the Mexican state of Mexico. There is a dubious ...prior record of a specimen collected on 1967. Either way this species has not been collected again until now.
We present a new record of rattlesnake Crotalus scutulatus collected in the county of La Paz, Mexico, that confirms the presence of the species for the Mexican state of Mexico. There is a dubious ...prior record of a specimen collected on 1967. Either way this species has not been collected again until now.
Postítulo restauración del patrimonio cultural mueble
En el presente informe se dan a conocer los procesos de conservación y ;
restauración de tres imágenes religiosas de madera policromada de los ...siglos ;
XVIII - XIX de talla popular chilena, pertenecientes a la zona central. Se dan a ;
conocer, además, el contexto histórico en el que fueron creadas, sus ;
antecedentes iconográficos, los diagnósticos que se realizaron previos a las ;
intervenciones efectuadas; los posibles deterioros a las que están expuestas ;
estas obras dadas sus características y cómo prevenir estos posibles daños.
Background Rapid and consistent genotyping is an important requirement for cultivar identification in many crop species. Among them grapevine cultivars have been the subject of multiple studies given ...the large number of synonyms and homonyms generated during many centuries of vegetative multiplication and exchange. Simple sequence repeat (SSR) markers have been preferred until now because of their high level of polymorphism, their codominant nature and their high profile repeatability. However, the rapid application of partial or complete genome sequencing approaches is identifying thousands of single nucleotide polymorphisms (SNP) that can be very useful for such purposes. Although SNP markers are bi-allelic, and therefore not as polymorphic as microsatellites, the high number of loci that can be multiplexed and the possibilities of automation as well as their highly repeatable results under any analytical procedure make them the future markers of choice for any type of genetic identification. Results We analyzed over 300 SNP in the genome of grapevine using a re-sequencing strategy in a selection of 11 genotypes. Among the identified polymorphisms, we selected 48 SNP spread across all grapevine chromosomes with allele frequencies balanced enough as to provide sufficient information content for genetic identification in grapevine allowing for good genotyping success rate. Marker stability was tested in repeated analyses of a selected group of cultivars obtained worldwide to demonstrate their usefulness in genetic identification. Conclusions We have selected a set of 48 stable SNP markers with a high discrimination power and a uniform genome distribution (2-3 markers/chromosome), which is proposed as a standard set for grapevine (Vitis vinifera L.) genotyping. Any previous problems derived from microsatellite allele confusion between labs or the need to run reference cultivars to identify allele sizes disappear using this type of marker. Furthermore, because SNP markers are bi-allelic, allele identification and genotype naming are extremely simple and genotypes obtained with different equipments and by different laboratories are always fully comparable.
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