Lifetime of superheated water in a micrometric synthetic fluid inclusion

International audienceA synthetic pure water fluid inclusion presenting a wide temperature range of metastability (Th - Tn ≈ 50°C; temperature of homogenization Th = 144°C and nucleation temperature of Tn = 89°C) was selected to make a kinetic study of the lifetime of an isolated microvolume of superheated water. The occluded liquid was placed in the metastable field by isochoric cooling and the duration of the metastable state was measured repetitively for 7 fixed temperatures above Tn. Statistically, measured metastability lifetimes for the 7 data sets follow the exponential Reliability distribution, i.e., the probability of non nucleation within time t equals . This enabled us to calculate the half-life periods of metastability Τ for each of the selected temperature, and then to predict Τ at any temperature T > Tn for the considered inclusion, according to the equation Τs , (∃T = T - Tn). Hence we conclude that liquid water in water-filled reservoirs with an average pore size ≈ 104 µm3 can remain superheated over geological timelengths (107s), when placed in the metastable field at 10°C above the average nucleation temperature, which often corresponds to high liquid tensions (≈ -120 -70 MPa)

Lifetime of superheated water in a micrometric synthetic fluid inclusion

A synthetic pure water fluid inclusion presenting a wide temperature range of metastability (Th - Tn ≈ 50°C; temperature of homogenization Th = 144°C and nucleation temperature of Tn = 89°C) was selected to make a kinetic study of the lifetime of an isolated microvolume of superheated water. The occluded liquid was placed in the metastable field by isochoric cooling and the duration of the metastable state was measured repetitively for 7 fixed temperatures above Tn. Statistically, measured metastability lifetimes for the 7 data sets follow the exponential Reliability distribution, i.e., the probability of non nucleation within time t equals . This enabled us to calculate the half-life periods of metastability τ for each of the selected temperature, and then to predict τ at any temperature T > Tn for the considered inclusion, according to the equation τ(s) = 22.1 × e1.046×ΔT , (ΔT = T - Tn). Hence we conclude that liquid water in water-filled reservoirs with an average pore size ≈ 104 µm3 can remain superheated over geological timelengths (1013s), when placed in the metastable field at 24°C above the average nucleation temperature, which often corresponds to high liquid tensions (≈ -50 MPa)

Experimental superheating of water and aqueous solutions

International audienceThe metastable superheated solutions are liquids in transitory thermodynamic equilibrium inside the stability domain of their vapor (whatever the temperature is). Some natural contexts should allow the superheating of natural aqueous solutions, like the soil capillarity (low T superheating), certain continental and submarine geysers (high T superheating), or even the water state in very arid environments like the Mars subsurface (low T) or the deep crustal rocks (high T). The present paper reports experimental measurements on the superheating range of aqueous solutions contained in quartz as fluid inclusions (Synthetic Fluid Inclusion Technique, SFIT) and brought to superheating state by isochoric cooling. About 40 samples were synthetized at 0.75 GPa and 530-700 °C with internally-heated autoclaves. Nine hundred and sixty-seven inclusions were studied by micro-thermometry, including measuring the temperatures of homogenization (Th: L + V → L) and vapor bubbles nucleation (Tn: L → L + V). The Th-Tn difference corresponds to the intensity of superheating that the trapped liquid can undergo and can be translated into liquid pressure (existing just before nucleation occurs at Tn) by an equation of state. Pure water (840-935 kg m−3), dilute NaOH solutions (0.1 and 0.5 mol kg−1), NaCl, CaCl2 and CsCl solutions (1 and 5 mol kg−1) demonstrated a surprising ability to undergo tensile stress. The highest tension ever recorded to the best of our knowledge (−146 MPa, 100 °C) is attained in a 5 m CaCl2 inclusion trapped in quartz matrix, while CsCl solutions qualitatively show still better superheating efficiency. These observations are discussed with regards to the quality of the inner surface of inclusion surfaces (high P-T synthesis conditions) and to the intrinsic cohesion of liquids (thermodynamic and kinetic spinodal). This study demonstrates that natural solutions can reach high levels of superheating, that are accompanied by strong changes of their physico-chemical properties

A coherent picture of water at extreme negative pressure.

International audienceLiquid water at atmospheric pressure can be supercooled to 41 C (ref. 1) and superheated to C302 C (ref. 2). Experiments involving fluid inclusions of water in quartz suggest that water is capable of sustaining pressures as low as 140 MPa before it breaks by cavitation3. Other techniques, for which cavitation occurs consistently at around 30MPa (ref. 4), produce results that cast doubt on this claim. Here we reproduce the fluid-inclusion experiment, performing repeated measurements on a single sample--a method used in meteorology5, bioprotection6 and protein crystallization7, but not yet in liquid water under large mechanical tension. The resulting cavitation statistics are characteristic of a thermally activated process, and both the free energy and the volume of the critical bubble are well described by classical nucleation theory when the surface tension is reduced by less than 10%, consistent with homogeneous cavitation. The line of density maxima of water at negative pressure is found to reach 922:8 kgm3 at around 300 K, which further constrains its contested phase diagram

Etude expérimentale de l'eau et de solutions aqueuses métastables implications pour le milieu naturel

Stretched (tensile) liquid water is a metastable liquid which persists at negative pressures in the stability field of vapour. The lifetime of metastability is limited. Tensions down to - 1400 bar have been specifically measured in aqueous inclusions inside quartz monocrystals. Vapour nucleation (Tn) marks the end of metastability. The destructive effects related to vapour nucleation in transiently tensile fluids are observed in nature: phreato-magmatic explosions, geysers. Modelling the kinetics of tensile water is critical in order to control the risks associated to metastable liquids. Quartz-hosted synthetic fluid inclusions (FI) with known densities and chemistries have been placed into the metastable tensile field by isochoric cooling and their Tn have been measured. We show that the tensile strength of water in individual FI depends on the FI volume and shape, the method used to synthetize the FI and the fluid chemistry. Experiments on metastability lifetimes have been performed by placing FI at temperatures 0.5° to 10°C above th eir Tn. Eigth FI were chosen that encompass the diversity of FI volumes, shapes, densities, fluid chemistries and tensile strengths. Our results show that tensile water lifetimes are all the shorter as the trapped water is more stretched. An empirical kinetic law is proposed that allows the lifetimes of tensile water in FI to be calculated as a function of the FI volume and Tn. Our data can also be reconciled with the Classical Nucleation Theory. Our data finally show that water in natural porous reservoirs can remain stretched for geologically-relevant timescales. Tensile water can therefore control fluid-rock interactions in the continental crust.L'eau tensile est de l'eau liquide métastable qui persiste dans le champ de stabilité de la vapeur à pression négative, sa durée de vie est finie. Des états de traction de l'eau jusqu'à -1400 bar ont été mesurés de façon spécifique dans des micro-inclusions intracristallines. La nucléation de vapeur (Tn) marque le retour à l'équilibre. Les effets destructeurs liés à la rupture d'états transitoires d'eau tensile sont observés dans le milieu naturel : explosions phréato-magmatiques, geysers. Modéliser la cinétique de l'eau métastable est fondamental pour gérer les risques qui lui sont associés. Des inclusions fluides synthétiques (IF) de composition et de densité connues, piégées dans du quartz, ont été placées dans le champ métastable par refroidissement isochore et leurs gammes de métastabilité ont été mesurées. On montre que la traction maximale de l'eau dans chaque IF dépend de son volume et de sa forme, de la méthode de synthèse de l'IF, de la chimie des solutions occluses. Des expériences de durée de vie ont été ensuite réalisées sur des IF placées de 0,5° à 10°C au-dessus de leurs Tn. Les 8 IF choisies rende nt compte de la diversité des formes, des volumes, des densités et gammes de traction observées. Les résultats montrent que la durée de vie de l'eau tensile en IF est d'autant plus courte que la traction de l'eau est plus forte. Une loi empirique est proposée qui permet de calculer la durée de vie de la métastabilité pour chaque IF de Tn et volume fixés. Par ailleurs, nos données peuvent être rendues compatibles avec la Théorie Classique de la Nucléation. Nos résultats montrent que l'eau dans les réservoirs poreux naturels peut rester métastable pendant des durées géologiques et ainsi, contrôler les interactions fluides-roches dans la croûte

Experimental study of water and aqueous solutions metastables : implications for the natural environment

L’eau tensile est de l’eau liquide métastable qui persiste dans le champ de stabilité de lavapeur à pression négative, sa durée de vie est finie. Des états de traction de l’eau jusqu’à -1400 baront été mesurés de façon spécifique dans des micro-inclusions intracristallines. La nucléation devapeur (Tn) marque le retour à l’équilibre. Les effets destructeurs liés à la rupture d’états transitoiresd’eau tensile sont observés dans le milieu naturel : explosions phréato-magmatiques, geysers.Modéliser la cinétique de l’eau métastable est fondamental pour gérer les risques qui lui sontassociés. Des inclusions fluides synthétiques (IF) de composition et de densité connues, piégées dansdu quartz, ont été placées dans le champ métastable par refroidissement isochore et leurs gammesde métastabilité ont été mesurées. On montre que la traction maximale de l’eau dans chaque IFdépend de son volume et de sa forme, de la méthode de synthèse de l’IF, de la chimie des solutionsoccluses. Des expériences de durée de vie ont été ensuite réalisées sur des IF placées de 0,5° à10°C au-dessus de leurs Tn. Les 8 IF choisies rende nt compte de la diversité des formes, desvolumes, des densités et gammes de traction observées. Les résultats montrent que la durée de viede l’eau tensile en IF est d’autant plus courte que la traction de l’eau est plus forte. Une loiempirique est proposée qui permet de calculer la durée de vie de la métastabilité pour chaque IF deTn et volume fixés. Par ailleurs, nos données peuvent être rendues compatibles avec la ThéorieClassique de la Nucléation. Nos résultats montrent que l’eau dans les réservoirs poreux naturels peutrester métastable pendant des durées géologiques et ainsi, contrôler les interactions fluides-rochesdans la croûte.Stretched (tensile) liquid water is a metastable liquid which persists at negative pressures inthe stability field of vapour. The lifetime of metastability is limited. Tensions down to - 1400 bar havebeen specifically measured in aqueous inclusions inside quartz monocrystals. Vapour nucleation (Tn)marks the end of metastability. The destructive effects related to vapour nucleation in transientlytensile fluids are observed in nature: phreato-magmatic explosions, geysers. Modelling the kinetics oftensile water is critical in order to control the risks associated to metastable liquids. Quartz-hostedsynthetic fluid inclusions (FI) with known densities and chemistries have been placed into themetastable tensile field by isochoric cooling and their Tn have been measured. We show that thetensile strength of water in individual FI depends on the FI volume and shape, the method used tosynthetize the FI and the fluid chemistry. Experiments on metastability lifetimes have been performedby placing FI at temperatures 0.5° to 10°C above th eir Tn. Eigth FI were chosen that encompass thediversity of FI volumes, shapes, densities, fluid chemistries and tensile strengths. Our results showthat tensile water lifetimes are all the shorter as the trapped water is more stretched. An empiricalkinetic law is proposed that allows the lifetimes of tensile water in FI to be calculated as a function ofthe FI volume and Tn. Our data can also be reconciled with the Classical Nucleation Theory. Our datafinally show that water in natural porous reservoirs can remain stretched for geologically-relevanttimescales. Tensile water can therefore control fluid-rock interactions in the continental crust

Fluid Inclusions, Solid-Solid Transitions in Salt, Ceramics and Minerals to Calibrate the Microthermometric Stage

International audienceThe Linkam THMS 600 microthermometric stage use the fluid inclusions to deliver quantitative paleo-temperatures of subsurface past environments that are critical not only for understanding past climate evolution but also to validate the outcome of predictive models of future climates. In this case, the calibration of the microthermometric stage is the primordial condition to have the most precise temperatures. Thus the calibration of the microthermometric stage is performed from −56 to +573 °C using reversible fusions or solid-solid transitions in standards as salts, ceramics, minerals or synthetic fluid inclusions. The nine transitions measured define a linear calibration curve with negative slope, showing a correction ranging from 1.6 to 16 °C between −60 and 600 °C. The vertical and lateral gradients (temperature bias) are estimated and discussed

Brillouin spectroscopy of fluid inclusions proposed as a paleothermometer for subsurface rocks

International audienceAs widespread, continuous instrumental Earth surface air temperature records are available only for the last hundred fifty years, indirect reconstructions of past temperatures are obtained by analyzing "proxies". Fluid inclusions (FIs) present in virtually all rock minerals including exogenous rocks are routinely used to constrain formation temperature of crystals. The method relies on the presence of a vapour bubble in the FI. However, measurements are sometimes biased by surface tension effects. They are even impossible when the bubble is absent (monophasic FI) for kinetic or thermodynamic reasons. These limitations are common for surface or subsurface rocks. Here we use FIs in hydrothermal or geodic quartz crystals to demonstrate the potential of Brillouin spectroscopy in determining the formation temperature of monophasic FIs without the need for a bubble. Hence, this novel method offers a promising way to overcome the above limitations