Stratigraphy and economic geology of uranium-bearing sediments in the Poison Spider District, Natrona County, Wyoming

Geologic, stratigraphic, and mineralogic characteristics of the Eocene Wind River and Oligocene White River Formations were determined for the southern portion of the Poison Spider District, Natrona County, Wyoming. Sieve analysis and heavy mineral techniques were used to recognize stratigraphic units, determine their environment of deposition, obtain a better knowledge of the grain size distribution, and to identify a possible source area for the sediments. Particular emphasis was concentrated on the evaluation and interpretation of the available geophysical data (gamma ray and resistivity logs), and geological information which had led to the establishment of several relationships between the local geology and the uraniferous mineralization. This mineralization is present in close association with carbonaceous material enclosed in the coarse, unconsolidated, arkosic sediments of the Wind River Formation. The uranium deposits are most likely epigenetic, with the carbonaceous material acting as one of the major precipitants of the uranyl ion from the mineralized ground water solutions. The uranium is believed to have been concentrated and brought to the area by meteoric waters which derived the metal from terrigenous sediments resulting from disintegration of Precambrian rocks (Granite Mountains), and/or Tertiary tuffaceous sediments (White River and Arikaree Formations). The mineralization found in the Wind River Formation has no economic value at present, due to its low grade character. Structural and tectonic features in Pliocene time is believed to have reversed the direction of the mineralized ground water flow coming to the area. This drainage change not only prevented the mineralization from reaching the Poison Spider area, but may also have caused leaching of some pre-existing uranium within the Wind River Formation --Abstract, pages ii-iii

Estratigrafía y análisis de facies de la Formación Vaca Muerta en el área de El Trapial

La importancia de los análisis estratigráficos, de facies y sedimentológicos para evaluar el potencial de un reservorio no convencional para identificar las zonas más favorables para la prospección y explotación de hidrocarburos.Fil: González Tomassini, Federico. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; ArgentinaFil: Kietzmann, Diego Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos ; ArgentinaFil: Fantin, Manuel A.. Chevron; ArgentinaFil: Crousse, Luisa C.. Chevron; ArgentinaFil: Reijenstein, Hernán M.. Chevron Latin America Business; Estados Unido

The role of discharge variability in the formation and preservation of alluvial sediment bodies

Extant, planform-based facies models for alluvial deposits are not fully fit for purpose, because they over-emphasise plan form whereas there is little in the alluvial rock record that is distinctive of any particular planform, and because the planform of individual rivers vary in both time and space. Accordingly, existing facies models have limited predictive capability. In this paper, we explore the role of inter-annual peak discharge variability as a possible control on the character of the preserved alluvial record. Data from a suite of modern rivers, for which long-term gauging records are available, and for which there are published descriptions of subsurface sedimentary architecture, are analysed. The selected rivers are categorized according to their variance in peak discharge or the coefficient of variation (CVQp = standard deviation of the annual peak flood discharge over the mean annual peak flood discharge). This parameter ranges over the rivers studied between 0.18 and 1.22, allowing classification of rivers as having very low ( 0.90) annual peak discharge variance. Deposits of rivers with very low and low peak discharge variability are dominated by cross-bedding on various scales and preserve macroform bedding structure, allowing the interpretation of bar construction processes. Rivers with moderate values preserve mostly cross-bedding, but records of macroform processes are in places muted and considerably modified by reworking. Rivers with high and very high values of annual peak discharge variability show a wide range of bedding structures commonly including critical and supercritical flow structures, abundant in situ trees and transported large, woody debris, and their deposits contain pedogenically modified mud partings and generally lack macroform structure. Such a facies assemblage is distinctively different from the conventional fluvial style recorded in published facies models but is widely developed both in modern and ancient alluvial deposits. This high-peak-variance style is also distinctive of rivers that are undergoing contraction in discharge over time because of the gradual annexation of the channel belt by the establishment of woody vegetation. We propose that discharge variability, both inter-annual peak variation and “flashiness” may be a more reliable basis for classifying the alluvial rock record than planform, and we provide some examples of three classes of alluvial sediment bodies (representing low, intermediate, and high/very high discharge variability) from the rock record that illustrate this point

Estratigrafía sísmica regional

El gran atractivo de la Fm. Vaca Muerta como reservorío no convencional de hidrocarburos ha despertado en simultaneo el interes de numerosos equipos de trabajo. Esta unidad ha sido historicdamente analizada en diversos ámbitos de la Cuenca Neuquina tanto desde la perspectivageológica como la paleontológica, en afloramientos y en subsuelo, en estudios regionales y locales. El tradicional interés petrolero por las Fms. Quintuco y Loma Montosa también fue de incentivo para la investigación del intervalo Tithoniano-Valanginiano inferior.Fil: Desjardins, Patricio. No especifíca;Fil: Fantín, Manuel. No especifíca;Fil: Gonzalez Tomassini, Federico. Ypf Sociedad Anonima. Gerencia de Geociencias y Reservorios; ArgentinaFil: Reijenstein, Hernán. No especifíca;Fil: Sattler, Federico. Petrobras Energia S.a.-planta Puerto Gr.san Martin; ArgentinaFil: Domínguez, Fabián. Ypf Sociedad Anonima. Gerencia de Geociencias y Reservorios; ArgentinaFil: Kietzmann, Diego Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Leanza, Hector Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Bande, Alejandro. No especifíca;Fil: Benoit, Sandra. Pan American Energy S.l. (pan American Energy S.l); ArgentinaFil: Borgnia, Marcela. No especifíca;Fil: Vittore, Franco. Ypf Sociedad Anonima. Gerencia de Geociencias y Reservorios; ArgentinaFil: Simo, Toni. No especifíca;Fil: Minisini, Daniel. No especifíca

Feasibility of steroid-free tacrolimus-basiliximab immunosuppression in pediatric liver transplantation and predictors for steroid requirement

Avoidance of steroids in pediatric liver transplantation may reduce toxicity and morbidity. The aim of this study was to analyze the feasibility of a steroid-free tacrolimus-basiliximab immunosuppression scheme, the risk factors associated with steroid requirement, and safety parameters. Patients who underwent liver transplantation for biliary atresia between 2011 and 2019 were included and followed for 6 months after transplantation. Immunosuppression consisted of tacrolimus-based treatment with basiliximab induction. Steroid-free survival was estimated, and risk factors for steroid requirement were evaluated using multivariate Cox regression analysis. A total of 76 patients were included, of whom 42 (55.3%) required steroids (>14 d) due to biopsy-proven acute rejection (47.6%, n = 20), instability in liver function tests (35.7%, n = 15), tacrolimus-related adverse drug reactions (14.3%, n = 6), or other reasons (bronchospasm episode, n = 1). Steroid-free survival was 45.9% (95% CI, 35.9-58.8). Independent factors associated with steroid requirement included tortuosity in tacrolimus trough levels (≥1.76 vs. <1.76: HR 5.8, 95% CI, 2.6-12.7; p < 0.001) and mean tacrolimus trough levels (≥ 6.4 ng/mL vs. < 6.4 ng/mL: HR 0.4, 95% CI, 0.2-0.7; p = 0.002). The rate of bacterial and viral infections was comparable between patients with and without steroids, although in the former group, cytomegalovirus infection developed earlier ( p = 0.03). Patients receiving steroids had higher total cholesterol, LDL, and HDL levels ( p < 0.05) during follow-up, but no changes in the height Z-score were observed 1 year after transplantation. Basiliximab induction in combination with tacrolimus-based treatment avoided steroid requirements in 45% of the patients. Tacrolimus variability and trough levels below 6.4 ng/mL independently increased the risk of steroid requirement. Further efforts should be focused on personalizing immunosuppressive treatment.Fil: Trezeguet Renatti, Guido. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Riva, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Minetto, Julia. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Reijenstein, Hayellen. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Gole, Maria. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Meza, Verónica. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Bosaleh, Andrea. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Licciardone, Nieves. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Aredes, Diego Eduardo. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Lauferman, Leandro. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Schaiquevich, Paula Susana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Cervio, Guillermo. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Dip, Marcelo Fabian. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Schaiquevich, Paula Susana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Halac, Esteban Tomas. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Imventarza, Oscar Cesar. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentin