Maturation of the Vaca Muerta and Agrio Formations due to the emplacement of magmatic intrusive complexes in the southern Men-doza region of the Neuquén Basin

La existencia de complejos intrusivos en cuencas sedimentarias ha sido documentada en varias cuencas en distintas partes delmundo. Generalmente se emplazan en rocas ricas en materia orgánica, produciendo la maduración de la misma. Además, el emplazamientopuede generar vías de migración de fluidos, estructuras que pueden ser posibles trampas de hidrocarburos, y pueden serreservorios fracturados. Este trabajo se focalizará en el impacto térmico y la consecuente generación de hidrocarburos producidospor el emplazamiento de un complejo intrusivo. Para ello se escogió el sector surmendocino de la Cuenca Neuquina, dónde existengran cantidad de intrusiones ígneas emplazadas en las rocas generadoras del Grupo Mendoza (Formaciones Vaca Muerta y Agrio)y en sedimentitas continentales del Grupo Neuquén. Se realizó la identificación de intrusivos mediante datos de sísmica y pozos. Seconfeccionó una sección estructural de la zona de estudio, para luego realizar los modelos termales. Los resultados de las modelizacionesmuestran que el emplazamiento de intrusivos genera la maduración de las Formaciones Vaca Muerta y Agrio, especialmentedonde se produce una clusterización de los intrusivos. Éste efecto está regulado por la temperatura de la roca de caja al tiempo delemplazamiento, la edad del emplazamiento y el solapamiento de las intrusiones. Se concluye que en la región surmendocina de laCuenca Neuquina, las Formaciones Vaca Muerta y Agrio se encuentran maduradas por el impacto térmico de un complejo intrusivo,pudiendo llegar a generar cantidades considerables de hidrocarburos.The existence of intrusive-complexes in sedimentary basins has been documented in many basins all around the world. Generally, they are emplaced in organic rich rocks, producing their maturation. Also, the emplacement can generate fluid's migration conduits, structures that can be hydrocarbon traps, and fractured reservoirs. This paper will focus on the thermal impact and the consequent hydrocarbon generation produced by the emplacement of an intrusive-complex. For that aim, we have chosen the southern Mendoza area of the Neuquén Basin, where a great quantity of igneous intrusions are emplaced in the source rocks of the Mendoza Group (Vaca Muerta and Agrio Formations), and in continental sedimentites of the Neuquén Group. The identification of the intrusives was made based on seismic and borehole data. We produced a structural section of the study area, which was used afterwards to make the thermal models. The results of our modellings show that the emplacement of intrusives generates the maturation of the Vaca Muerta and Agrio Formations, especially where a clustering of the intrusions is produced. This effect is regulated by the temperature of the host rock at the time of emplacement, the age of the emplacement, and the clustering of intrusions. We conclude that in the southern Mendoza region of the Neuquén Basin, the Vaca Muerta and Agrio Formations were matured because of the thermal impact of an intrusive complex, being able to generate considerable amount of hydrocarbons.Fil: Spacapan, Juan Bautista. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina. YPF - Tecnología; ArgentinaFil: Palma, Joaquín Octavio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. YPF - Tecnología; ArgentinaFil: Rocha Vargas, Marcelo Emilio. YPF - Tecnología; 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: D'Odorico, Alejandro. YPF - Tecnología; ArgentinaFil: Rojas Vera, Emilio Agustin. YPF - Tecnología; ArgentinaFil: Manceda, René Enrique. YPF - Tecnología; ArgentinaFil: Galland, Olivier. University of Oslo; NoruegaFil: Medialdea, Adrián. YPF - Tecnología; ArgentinaFil: Cattaneo, Diego Matias. YPF - Tecnología; Argentin

Nightside condensation of iron in an ultra-hot giant exoplanet

Ultra-hot giant exoplanets receive thousands of times Earth's insolation. Their high-temperature atmospheres (>2,000 K) are ideal laboratories for studying extreme planetary climates and chemistry. Daysides are predicted to be cloud-free, dominated by atomic species and substantially hotter than nightsides. Atoms are expected to recombine into molecules over the nightside, resulting in different day-night chemistry. While metallic elements and a large temperature contrast have been observed, no chemical gradient has been measured across the surface of such an exoplanet. Different atmospheric chemistry between the day-to-night ("evening") and night-to-day ("morning") terminators could, however, be revealed as an asymmetric absorption signature during transit. Here, we report the detection of an asymmetric atmospheric signature in the ultra-hot exoplanet WASP-76b. We spectrally and temporally resolve this signature thanks to the combination of high-dispersion spectroscopy with a large photon-collecting area. The absorption signal, attributed to neutral iron, is blueshifted by -11+/-0.7 km s-1 on the trailing limb, which can be explained by a combination of planetary rotation and wind blowing from the hot dayside. In contrast, no signal arises from the nightside close to the morning terminator, showing that atomic iron is not absorbing starlight there. Iron must thus condense during its journey across the nightside.Comment: Published in Nature (Accepted on 24 January 2020.) 33 pages, 11 figures, 3 table

Low resistivity zones at contacts of igneous intrusions emplaced in organic-rich formations and their implications on fluid flow and petroleum systems: a case study in the northern Neuquén Basin, Argentina

Igneous sills and laccoliths emplaced in sedimentary basins may significantly impact petroleum systems, both positively and negatively. Igneous intrusions provide heat to maturate regionally immature organic‐rich host rocks, act as fractured reservoirs hosting commercial accumulations of hydrocarbons, and form structures affecting fluid flow and trapping at different scales. Nevertheless, the petrophysical implications of igneous intrusions on their host rock are poorly known. In this study, we analyse 200 wells in the Río Grande Valley oil field, Neuquén basin, Argentina, where the main reservoirs are in fractured igneous sills. This dataset represents a globally unique possibility to characterize the igneous–host rock interaction using both wireline logs and core material. We identify a systematic Contact Low Resistivity Zone (CLRsZ) at both the upper and lower contacts of the sills emplaced in the organic‐rich Vaca Muerta and Agrio Formations. We characterize the nature of these CLRsZ and their petrophysical properties by integrating resistivity and gamma ray well logs, petrographic analyses, petrophysical tests and geochemical analyses. The low resistivity signal of the CLRsZ is dominantly carried by massive‐sulphide deposits, mainly pyrite, observed both in the host rock and the chilled margin of the sills. Well log images and porosity‐permeability analysis on core plugs show that both the sills and their associated CLRsZ can act as carrier for fluid flow and reservoir for hydrocarbons storage. The thickness of the upper and lower CLRsZ correlates linearly with the thickness of the sill, and the volume of both the upper and lower CLRsZ represents ca. 40% with respect to the volume of their associated sill. The thickness of the CLRsZ represents ca. 13% of the thickness of contact aureole induced by the sills. In the CLRsZ, a great proportion of kerogen was transformed to hydrocarbon, so that CLRsZ were restricted to the innermost contact aureole of the sills. Our results show that the CLRsZ can have major implications on fluid flow and should be considered in reservoir models in volcanic basins hosting sills emplaced in organic‐rich formations

Fundamental physics with ESPRESSO: Constraining a simple parametrisation for varying

Context. The spectrograph ESPRESSO recently obtained a limit on the variation of the fine-structure constant, α, through measurements along the line of sight of a bright quasar with a precision of 1.36 ppm at 1σ level. This imposes new constraints on cosmological models with a varying α. We assume such a model where the electromagnetic sector is coupled to a scalar field dark energy responsible for the current acceleration of the Universe. We parametrise the variation of α with two extra parameters, one defining the cosmological evolution of the quintessence component and the other fixing the coupling with the electromagnetic field. Aims. The objective of this work is to constrain these parameters with both astrophysical and local probes. We also carried out a comparative analysis of how each data probe may constrain our parametrisation. Methods. We performed a Bayesian analysis by comparing the predictions of the model with observations. The astrophysical datasets are composed of quasar spectra measurements, including the latest ESPRESSO data point, as well as Planck observations of the cosmic microwave background. We combined these with local results from atomic clocks and the MICROSCOPE experiment. Results. The constraints placed on the quintessence parameter are consistent with a null variation of the field, and are therefore compatible with a ΛCDM cosmology. The constraints on the coupling to the electromagnetic sector are dominated by the Eötvös parameter local bound. Conclusions. More precise measurements with ESPRESSO will be extremely important to study the cosmological evolution of α as it probes an interval of redshift not accessible to other types of observations. However, for this particular model, current available data favour a null variation of α resulting mostly from the strong MICROSCOPE limits