Search results for "Universe"
showing 10 items of 2171 documents
Différentes approches pour la datation U/Pb des tonsteins intercalés dans les séries continentales d’âge fini-carbonifère à permien de Lucenay-lès-Ai…
2018
International audience; D’une manière générale, la présence de niveaux volcaniques (cendres ou laves) intercalés dans les séries sédimentaires présente un avantage non négligeable pour dater la sédimentation de ces séries. Des datations précises peuvent même permettre d’estimer des taux de sédimentation, ou encore de proposer des corrélations à l’échelle de différents bassins.Les séries sédimentaires du Carbonifère-Permien de Lucenay-lès-Aix, étudiées par forage, sont géographiquement situées entre des séries de même âge connues à l’affleurement : Decize-La Machine (au nord), Aumance (à l’ouest) et Autun (à l’est). Ce (ou ces) bassin(s) sont consti- tués de dépôts continentaux dans lesquels…
Caractérisation pétro-géochimique et datation U/Pb du volcanisme contemporain des bassins d’âge fini-Carbonifère à Permien du Nord du Massif Central
2018
International audience; La formation de la chaîne hercynienne, dont l’apogée a lieu au Carbonifère, participe à l’assemblage de la Pangée, qui se démantèlera par la suite à partir du Trias. La limite Carbonifère- Permien correspond donc à une période clé dans l’évolution géodynamique globale, à la transition entre une période orogénique et une période de rifting. Cependant, les reconstitutions paléogéographiques et paléoclimatiques pour cette époque sont assez peu contraintes, notamment du fait du manque de datations radiométriques et de corrélations stratigraphiques fiables entre les différents domaines sédimentaires. Plusieurs bassins sédimentaires fini-carbonifères à permiens sont préser…
A Raman calibration for the quantification of SO42-groups dissolved in silicate glasses: Application to natural melt inclusions
2017
Sulfur is an important volatile element involved in magmatic systems. Its quantification in silicate glasses relies on state-of-the-art techniques such as electronprobe microanalyses (EPMA) or X-ray absorption spectroscopy but is often complicated by the fact that S dissolved in silicate glasses can adopt several oxidation states (S6+for sulfates or S2-for sulfides). In the present work, we use micro-Raman spectroscopy on a series of silicate glasses to quantify the S content. The database is constituted by 47 silicate glasses of various compositions (natural and synthetic) with S content ranging from 1179 to 13 180 ppm. Most of the investigated glasses have been synthesized at high pressur…
Molecular Selectivity of CO–N 2 Mixed Hydrates: Raman Spectroscopy and GCMC Studies
2020
This paper reports a novel quantitative investigation concerning the CO selectivity properties for mixed CO–N2 hydrates. The study was developed by combining Raman scattering experiments and grand ...
Water solubility in trachytic and pantelleritic melts: an experimental study
2021
International audience; Solubility experiments were performed on a trachyte and a pantellerite from Pantelleria. The trachyte has SiO 2 = 65.2 wt%, Al 2 O 3 = 15.2 wt% and a peralkaline index (P.I. = molar[(Na 2 O + K 2 O)/Al 2 O 3 ]) ∼ 1 while the pantellerite has SiO 2 = 72.2 wt%, Al 2 O 3 = 11 wt% and a P.I. = 1.3. Solubility experiments were performed in the pressure range of 50-300 MPa at T = 950°C for the trachyte and 50-200 MPa at T = 850°C for the pantellerite. The water content of experimental glasses was determined by Karl Fischer titration, elemental analyser and FT-IR spectroscopy. Water content appears similar in both compositions for analogous pressure conditions, varying from…
Electronic Band Transitions in γ-Ge3N4
2021
This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. Support from Estonian Research Council grant PUT PRG 619 is gratefully acknowledged. The multi-anvil experiments at LMV were supported by the French Government Laboratory of Excellence initiative no ANR-10-LABX-0006, the Région Auvergne and the European Regional Development Fund (ClerVolc Contribution Number 478).
A multi-technique characterisation of cronstedtite synthetized by iron-clay interaction in a step by step cooling procedure
2013
International audience; The cooling of steel containers in radioactive-waste storage was simulated in a step-by-step experiment from 90 to 40 degrees C. Among newly formed clay minerals observed in run products, cronstedtite was identified by a number of analytical techniques (powder X-ray diffraction, transmission electron microscopy, and scanning electron microscopy). Cronstedtite has not previously been recognized to be so abundant and so well crystallized in an iron-clay interaction experiment. The supersaturation of experimental solutions with respect to cronstedtite was due to the availability of Fe and Si in solution, as a result of the dissolution of iron metal powder, quartz, and m…
Stand-Off Magnetometry with Directional Emission from Sodium Vapors
2021
International audience; Stand-off magnetometry allows measuring magnetic field at a distance, and can be employed in geophysical research, hazardous environment monitoring, and security applications. Stand-off magnetometry based on resonant scattering from atoms or molecules is often limited by the scarce amounts of detected light. The situation would be dramatically improved if the light emitted by excited atoms were to propagate towards the excitation light source in a directional manner. Here, we demonstrate that this is possible by means of mirrorless lasing. In a tabletop experiment, we detect free-precession signals of ground-state sodium spins under the influence of an external magne…
Adsorption of CO and N 2 molecules at the surface of solid water. A grand canonical Monte Carlo study
2020
International audience; The adsorption of carbon monoxide and nitrogen molecules at the surface of four forms of solid water is investigated by means of grand canonical Monte Carlo simulations. The trapping ability of crystalline Ih and low-density amorphous ices, along with clathrate hy-drates of structures I and II, are compared at temperatures relevant for astrophysics. It is shown that, when considering a gas phase that contains mixtures of carbon monoxide and nitrogen, the trapping of carbon monoxide is favored with respect to that of nitrogen at the surface of all solids, irrespective of the temperature. The results of the calculations also indicate that some amounts of molecules can …
High-temperature emission spectroscopy of methane
2008
International audience; A high-enthalpy source (HES) has been developed in Rennes either to heat gases up to 2000K in local thermodynamic equilibrium (LTE) or to generate hypersonic expansions. The HES prototype has been associated with a high-resolution Bruker IFS 120 HR Fourier transform spectrometer to record emission spectra of hot gases, in LTE conditions. A series of emission spectra of methane has been obtained at 1005, 1365, 1485, 1625 and 1820K in the pentad spectral region located around 3000 cm1, at Doppler-limited resolution (0.02 cm1). Spectra have been corrected for the transmission function that strongly affects the infrared radiation emitted by the hot gas. Line-integrated a…