A high temperature equation of state for the H2O-CaCl2 and H2O-MgCl2 systems

Duan, Zhenhao; Møller, Nancy; Weare, John H.

doi:10.1016/j.gca.2006.05.007

Cited by 27 publications

(13 citation statements)

References 61 publications

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“…For Th lower than 250 °C, the internet soft (http://www.geochem-model.org/models/h2o_cacl2/index.htm, details in Mao and Duan, 2008) was used with the same procedure as that for NaCl, except for one aspect: the isochore extrapolated to convert (Tn, ρ BULK ) into pressure coordinates was a mean isochore for each sample. For Th greater than 250 °C, the same procedure was used with the h2o_cacl2 application (based on the scientific frame exposed in Duan et al, 2006), which can be downloaded from the Geochimica website (supplementary data of Duan et al, 2006Duan et al, : doi:10.1016Duan et al, /j.gca.2006. Finally, the location of the spinodal curve was assessed by displacing the pure water spinodal (keeping constant its exact shape) to fit the known critical point of CaCl 2 (here up to 2 m after Shibue, 2003).…”

Section: Cacl 2 Solutionsmentioning

confidence: 99%

Experimental superheating of water and aqueous solutions

Shmulovich

Mercury

Thiéry

et al. 2009

Geochimica et Cosmochimica Acta

101

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The 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, CaCl 2 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 CaCl 2 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 physicochemical properties.

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Section: Cacl 2 Solutionsmentioning

confidence: 99%

Experimental superheating of water and aqueous solutions

Shmulovich

Mercury

Thiéry

et al. 2009

Geochimica et Cosmochimica Acta

101

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“…(1992c, 1996), Shi & Saxena (1992) and Churakov & Gottschalk (2003a,b) for H 2 O–CO 2 –CH 4 plus additional phase components. H 2 O–salt systems are covered by Anderko & Pitzer (1993a,b) for H 2 O–NaCl–KCl, Jiang & Pitzer (1996) for H 2 O–CaCl 2 and Duan et al. (2006) for H 2 O–CaCl 2 and H 2 O–MgCl 2 .…”

Section: Binary and Ternary Fluid Systemsmentioning

confidence: 99%

Aqueous fluids at elevated pressure and temperature

Liebscher

2010

Geofluids

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The general major component composition of aqueous fluids at elevated pressure and temperature conditions can be represented by H 2 O, different non-polar gases like CO 2 and different dissolved metal halides like NaCl or CaCl 2 . At high pressure, the mutual solubility of H 2 O and silicate melts increases and also silicates may form essential components of aqueous fluids. Given the huge range of P-T-x regimes in crust and mantle, aqueous fluids at elevated pressure and temperature are highly variable in composition and exhibit specific physicochemical properties. This paper reviews principal phase relations in one-and two-component fluid systems, phase relations and properties of binary and ternary fluid systems, properties of pure H 2 O at elevated P-T conditions, and aqueous fluids in H 2 O-silicate systems at high pressure and temperature. At metamorphic conditions, even the physicochemical properties of pure water substantially differ from those at ambient conditions. Under typical mid-to lower-crustal metamorphic conditions, the density of pure H 2 O is q H2O ¼ 0:6À1:0 g cm À3 , the ion product K w = 10 )7.5 to approximately 10 )12.5 , the dielectric constant e = 8-25, and the viscosity g = 0.0001-0.0002 Pa sec compared to q H2O ¼ 1:0 g cm À3 , K w = 10 )14 , e = 78 and g = 0.001 Pa sec at ambient conditions. Adding dissolved metal halides and non-polar gases to H 2 O significantly enlarges the pressure-temperature range, where different aqueous fluids may co-exist and leads to potential two-phase fluid conditions under must mid-to lower-crustal P-T conditions. As a result of the increased mutual solubility between aqueous fluids and silicate melts at high pressure, the differences between fluid and melt vanishes and the distinction between fluid and melt becomes obsolete. Both are completely miscible at pressures above the respective critical curve giving rise to so-called supercritical fluids. These supercritical fluids combine comparably low viscosity with high solute contents and are very effective metasomatising agents within the mantle wedge above subduction zones.

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“…Thus, the consequences of vapor-liquid exchange and subsequent physical separation of low-density vapor from saline liquid in open systems must be addressed by observation (Giggenbach 1971), theory (Bowers and Helgeson 1983a,b;Shinohara 1994;Duan et al 1995Duan et al , 2006, and experiment (Bischoff and Pitzer 1989;Shinohara et al 1989;Bodnar 2003).…”

Section: Consequences Of Two Fl Uids In Volcanic Environmentsmentioning

confidence: 99%

“…Fluid phase equilibria are strong functions of temperature and pressure; so, two-phase volcanic fl uids are common given the broad temperature and pressure ranges that characterize volcanoes and their plumbing systems. The involvement of multiple fl uids in volcanic processes is important because heat and mass transport in two-fl uid systems can be signifi cantly different from those in one-fl uid systems and because phase separation generates fl uids with different compositions, densities, and mobilities as they fl ow through magma and rock (Duan et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Fluid Immiscibility in Volcanic Environments

Webster

Mandeville

2007

Reviews in Mineralogy and Geochemistry

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INTRODUCTIONVolatile components enter the atmosphere, oceans, and other surface waters through pre-, syn-, and post-eruptive volcanic processes that involve a variety of fl uids. Aluminosilicate-poor fl uids include aqueous or carbonic to sulfi de-, sulfate-, chloride-, fl uoride-, carbonate-, and phosphate-rich compositions in volcanic environments, but other more complex combinations of these constituents may be involved (Giggenbach 1977;Roedder 1984 Roedder , 1992Lowenstern 1995). Other, rare gases and dissolved constituents (e.g., H 2 , N 2 , He, Ar, H 3 BO 3 , Hg, CH 4 and other hydrocarbon compounds, metals, and metalloids) are also present, but in general they are not suffi ciently concentrated to form their own phases or control bulk-fl uid composition and volcanic processes. As a result of their diverse compositions, volcanic fl uids ranging from vapor to liquid exhibit widely different densities and show strong distinctions in heat capacity, dielectric behavior, viscosity, and other chemical and physical characteristics (Geiger et al. 2006a). The density of a saline liquid in the system NaCl-H 2 O at 50 MPa and 800 °C, for example, is more than 7 times that of the coexisting aqueous vapor (e.g., 0.2 gm/cm 3 ) (Henley and McNabb 1978).Multiple fl uids move, mix, and/or unmix in magma chambers and volcanic conduits, in the root zone of fumaroles, and in the convective hydrothermal systems that are ubiquitous to volcanic environments. Hydrothermal systems are typically centered on magmatic intrusions and may include crater lakes at the top of eruptive conduits. Hydrothermal processes involving two or more fl uid phases operate through a variety of geologically relevant, shallowcrustal pressure-temperature-composition conditions. Volcanic fl uids occur at supersolidus to subsolidus conditions, meaning that the dense aluminosilicate melt that is common to volcanism may or may not be present. This chapter addresses the evidence for and occurrence of two or more low-density, aluminosilicate-poor fl uids in volcanic and related environments. It also describes the role of multiple fl uids in the chemical and physical processes that occur in these environments-even though many aspects of volcanic processes are still poorly understood. BACKGROUND

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A high temperature equation of state for the H2O-CaCl2 and H2O-MgCl2 systems

Cited by 27 publications

References 61 publications

Experimental superheating of water and aqueous solutions

Experimental superheating of water and aqueous solutions

Aqueous fluids at elevated pressure and temperature

Fluid Immiscibility in Volcanic Environments

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