Strain response and re-equilibration of CH₄-rich synthetic aqueous fluid inclusions in calcite during pressure drops     

Julien Bourdet  Jacques Pironon 《Geochimica et cosmochimica acta》2008,72(12):2946-2959

Aqueous fluids in sedimentary basins often contain dissolved methane, particularly in petroleum environments. PVTX (Pressure-Volume-Temperature-Composition) reconstructions performed using fluid inclusion data are largely based on the assumption that inclusions do not change from the time of trapping until the present. Many authors, however, consider that fluid inclusions can re-equilibrate, particularly in fragile minerals like calcite. In order to understand this re-equilibration phenomenon in the metamorphic domain, previous experiments have been performed under high PT conditions, but few have been performed at low to medium PT conditions such as those associated with sedimentary burial diagenesis, and no previous studies have examined CH₄-bearing aqueous inclusions in calcite.An experimental study of the preservation/modification of CH₄-rich synthetic fluid inclusions in calcite during isothermal decompression was conducted. An autoclave was used for accurate PTX control allowing equilibrium between liquid and vapour in the CH₄-H₂O system. PTX conditions were maintained at four stages of decreasing pressure, with each stage held for 7 days to simulate an isothermal pressure drop. In order of decreasing pressure, the pressure-temperature conditions monitored were 276 ± 10 bar at 180 ± 7 °C, 176 ± 10 bar at 180 ± 7 °C, 76 ± 10 bar at 180 ± 7 °C and 10 ± 3 bar at 180 ± 15 °C. At the end of the experiment, the calcite was recovered and analyzed by microthermometry and Raman microspectroscopy for PTX reconstruction. A careful procedure was adopted to limit re-equilibration of inclusions during analytical procedures. Four types of inclusion shapes and four types of strain patterns were differentiated. Classification of the petrographic strain patterns was carried out. These strain patterns were associated with inclusion stretching and/or leakage regarding CH₄, T_h and P_h compared to experimental conditions. Factors controlling the preservation or acquisition of strain patterns included the initial shape and size of the inclusion, and the pressure differential (ΔP) between the confining pressure (P_cf) and the internal pressure (P_i) within the inclusion. Most fluid inclusions seemed to be trapped during the first 7 days of the experiment, although few (4%) of these preserved the initial PT conditions of 276 ± 10 bar, whereas 8% preserved the second and third run of PT conditions. Overall, the majority of inclusions (88%) did not reflect accurately the PTX trapping conditions. A petrographic guide to the inclusions is presented here that allows strain identification for PVT reconstructions. Re-equilibration patterns and evidence for preferential methane leakage from aqueous inclusions in calcite are important findings revealed by this study, and may be useful for the reconstruction of post-trapping events in investigations of natural samples, and in other experiments using synthetic inclusions in calcite.  相似文献   

Analysis of nocturnal air temperature in districts using mobile measurements and a cooling indicator     

Leconte  François  Bouyer  Julien  Claverie  Rémy  Pétrissans  Mathieu 《Theoretical and Applied Climatology》2017,130(1-2):365-376

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A vibrational study of phase transitions among the GeO2 polymorphs     

M. Madon  Ph. Gillet  Ch. Julien  G. D. Price 《Physics and Chemistry of Minerals》1991,18(1):7-18

Infrared and Raman spectra of the quartz, rutile and amorphous forms of GeO₂ have been recorded under pressure and/or temperature, in order to study the crystalline to crystalline — or amorphous — transformations of this compound in the solid state. X-ray diffraction data shown that crystalline quartz-GeO₂ subjected to high pressure amorphizes. Infrared data are consistent with a gradual amorphisation of this compound at static pressures between 6 to 12 GPa at 300 K. With increasing pressure, the Ge-O distance appears to remain constant and amorphization is associated with a progressive change in the coordination of germanium atoms from fourfold to sixfold. This apparent change in coordination is not quenchable at room pressure. On decompression, the Ge in the amorphous form returns to tetrahedral coordination. The anharmonic parameters for the Raman modes of the quartz and rutile forms of GeO₂, have also been estimated from pressure and temperature shifts. These data have been used to calculate heat capacities and entropies of the two polymorphs at different pressures, with the Kieffer vibrational model. The calculated heat capacities at room pressure are within 1% of the experimental values between 20 and 1500 K. The calculated entropies are used to estimate the phase boundary in the (P, T) plane. The slope of the curve at room pressure (17 bar/K) is in good agreement with experimental values.  相似文献   

Detection of anthropogenic influence on the evolution of record-breaking temperatures over Europe     

Margot Bador  Laurent Terray  Julien Boé 《Climate Dynamics》2016,46(9-10):2717-2735

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Modelling in-situ upgrading of heavy oil using operator splitting method     

Julien Maes  Ann H. Muggeridge  Matthew D. Jackson  Michel Quintard  Alexandre Lapene 《Computational Geosciences》2016,20(3):581-594

The in-situ upgrading (ISU) of bitumen and oil shale is a very challenging process to model numerically because of the large number of components that need to be modelled using a system of equations that are both highly non-linear and strongly coupled. Operator splitting methods are one way of potentially improving computational performance. Each numerical operator in a process is modelled separately, allowing the best solution method to be used for the given numerical operator. A significant drawback to the approach is that decoupling the governing equations introduces an additional source of numerical error, known as the splitting error. The best splitting method for modelling a given process minimises the splitting error whilst improving computational performance compared to a fully implicit approach. Although operator splitting has been widely used for the modelling of reactive-transport problems, it has not yet been applied to the modelling of ISU. One reason is that it is not clear which operator splitting technique to use. Numerous such techniques are described in the literature and each leads to a different splitting error. While this error has been extensively analysed for linear operators for a wide range of methods, the results cannot be extended to general non-linear systems. It is therefore not clear which of these techniques is most appropriate for the modelling of ISU. In this paper, we investigate the application of various operator splitting techniques to the modelling of the ISU of bitumen and oil shale. The techniques were tested on a simplified model of the physical system in which a solid or heavy liquid component is decomposed by pyrolysis into lighter liquid and gas components. The operator splitting techniques examined include the sequential split operator (SSO), the Strang-Marchuk split operator (SMSO) and the iterative split operator (ISO). They were evaluated on various test cases by considering the evolution of the discretization error as a function of the time-step size compared with the results obtained from a fully implicit simulation. We observed that the error was least for a splitting scheme where the thermal conduction was performed first, followed by the chemical reaction step and finally the heat and mass convection operator (SSO-CKA). This method was then applied to a more realistic model of the ISU of bitumen with multiple components, and we were able to obtain a speed-up of between 3 and 5.  相似文献   

Agonistic effect of imidazole and triazole fungicides on in vitro oocyte maturation in rainbow trout (Oncorhynchus mykiss)     

Gilles Monod  Hlne Rime  Julien Bobe  Bernard Jalabert 《Marine environmental research》2004,58(2-5):143

The purpose of the present study was to assess the in vitro effect of some imidazole (prochloraz, imazalil) and triazole (epoxiconazole) agricultural fungicides on gonadotropin-induced oocyte maturation in rainbow trout. Results show that prochloraz, epoxiconazole and imazalil strongly potentiated the induction of oocyte maturation by gonadotropin in a dose-dependent manner. Furthermore, 10⁻⁵ M prochloraz and epoxiconazole alone induced oocyte maturation. The mRNA biosynthesis inhibitor, actinomycin , completely inhibited oocyte maturation induced by fungicides, suggesting that the gonadotropin-like effect of these chemicals is at least dependent on de novo gene expression.  相似文献   

Hamilton's principle and the vorticity laws for a relativistic perfect fluid     

Rick Salmon 《地球物理与天体物理流体动力学》2013,107(2):167-179

Abstract

The equations for a relativistic perfect fluid result from the requirement that the total mass-energy be stationary with respect to variations δx^α(a, b, c, s) in the space-time location of the fluid particle identified by Lagrangian labels (a, b, c) at the point s on its world-line. By considering variations of the Lagrangian labels that leave the specific volume and entropy unchanged, we obtain a general covariant statement of vorticity conservation. The conservation laws for circulation, potential vorticity, and helicity are simple corollaries. This Noether-theorem derivation shows that the vorticity laws have no analogues in particle mechanics, where the corresponding particle labels cannot be continuously vaned.  相似文献   

Neogene exhumation and relief evolution in the eastern Betics (SE Spain): Insights from the Sierra de Gador          下载免费PDF全文

Marianne Janowski  Nicolas Loget  Cécile Gautheron  Jocelyn Barbarand  Nicolas Bellahsen  Jean Van Den Driessche  Julien Babault  Bertrand Meyer 《地学学报》2017,29(2):91-97

The Betics are a key area to study an orogenic landscape disrupted by late‐orogenic extension. New low‐temperature thermochronology (LTT) data (AHe and AFT) coupled with geomorphic constraints in the Sierra de Gador (Alpujarride complex) are used to reconstruct the cooling history and evolution of relief during the Neogene. We document three stages: (1) a fast cooling event between 23 and 16 Ma associated with the well‐known extensive tectonic exhumation of the Alpujarride unit, (2) a period of slow cooling between 16 and 7.2 Ma related to a planation event and (3) a post‐7.2 Ma surface uplift associated with the inversion of the Alboran domain undetected by LTT. The planation event followed by this late uplift can explain the occurrence of inherited low‐relief surfaces overlain by Tortonian–Messinian platform deposits at the top of the range. Finally, we propose that the Sierra de Gador is a more transient landscape than the nearby Sierra Nevada.  相似文献   

Influence of the El Niño/Southern Oscillation on South Korean streamflow variability          下载免费PDF全文

Jai Hong Lee  Pierre Y. Julien 《水文研究》2017,31(12):2162-2178

Deciphering the mechanisms through which the El Niño/Southern Oscillation (ENSO) affects hydrometeorological parameters in the tropics and extratropics is of great interest. We investigate climatic teleconnections between warm or cold phases of ENSO and streamflow patterns over South Korea using an empirical methodology designed to detect regions showing a strong and consistent hydroclimatic signal associated with ENSO. We calculate not only spatial coherence values by monthly streamflow composite formed over 2‐year ENSO cycle and the first harmonic fit to detect candidate regions but also temporal consistency rates by aggregate composite and index time series to determine core regions. As a result, the core regions, namely, the Han river basin and the Nakdong river basin, are detected with a high level of response of ENSO phenomena to streamflow patterns. The ENSO composites for both core regions indicate drier (wetter) conditions in early autumn of the warm (cold) episode years and wetter (drier) conditions from winter to spring of the following year. For both regions, the spatial coherences are over 92% (82%) and the temporal consistencies are 71% (75%) during the El Niño (La Niña) events. In addition, for the core regions identified by composite‐harmonic analysis for both extreme episodes, the results of comparative analyses by using correlation, annual cycle, and Wilcoxon rank sum test indicate that 2 opposite phases‐streamflow relationships have a tendency of sign reversal of the streamflow anomaly. Also, the positive departures during the El Niño years show more coherent and strong responses than the negative anomalies in the La Niña events. In conclusion, South Korea experiences climatic teleconnection between ENSO forcing and midlatitude streamflow patterns.  相似文献   

Carbon and suspended sediment transport in an impounded alpine river (Isère,France)     

Julien Némery  Vincent Mano  Alexandra Coynel  Henri Etcheber  Florentina Moatar  Michel Meybeck  Philippe Belleudy  Alain Poirel 《水文研究》2013,27(17):2498-2508

Carbon and total suspended sediment (TSS) loads were investigated from April 2006 to March 2008 in the mountainous watershed of the Isère River, French Alps (5570 km²). The river bed has been highly impounded for hydroelectricity production during the last century. Hydraulic flushes are managed every year to prevent TSS storage within upstream dams. The Isère River has been instrumented for high‐frequency monitoring of water, TSS by turbidity and carbon (organic, inorganic, dissolved and particulate) in order to evaluate the impact of natural floods and hydraulic flushes on annual loads. Annual TSS load which was estimated between 1.3 and 2.3 MT y^?1 (i.e. 233 to 413 T km^?2 y^?1) highlighted the high erodibility of the Isère watershed. Annual carbon load was estimated between 173 10³ T y^?1 and 199 10³ T y^?1 (i.e 31 to 36 T km^?2 y^?1). About 80% of the annual carbon loads were inorganic. The impact of hydraulic flushes on annual loads appeared limited (less than 3% for annual TSS load and about 1.5% for annual carbon load), whereas the most important natural flood event contributed to 20% of the annual TSS load and 10% of the annual carbon load. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献