H<sub>2</sub>O solubility in haplogranitic melts; compositional, pressure, and temperature dependence

Holtz, François; Behrens, Harald; Dingwell, Donald B.; Johannes, Wilhelm

doi:10.2138/am-1995-1-210

Cited by 293 publications

(135 citation statements)

References 23 publications

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“…The quantitative treatment of the relation between water activity and redox conditions (and oxidation state of iron) is given by Botcharnikov et al [2005]. The water-saturation curve included in the phase diagrams is obtained from the water solubility in a primitive MORB of Berndt et al [2002] and from the temperature and pressure dependence on water solubility of Holtz et al [1995].…”

Section: A1 Relation Between Water and Oxygen Fugacitymentioning

confidence: 99%

Root zone of the sheeted dike complex in the Oman ophiolite

Nicolas

Boudier

Koepke

et al. 2008

Geochem Geophys Geosyst

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[1] In the Oman ophiolite crustal section, a contact zone between the gabbro unit and the volcanics and diabase sheeted dikes, called the root zone of the sheeted dike complex, has been recently mapped at a fine scale in a selected area. The Oman ophiolite is derived from a fast spreading ridge which had a melt lens located between the main gabbro unit and the root zone of the sheeted dike complex. With a few exceptions accounted for, this horizon has a fairly constant thickness, $100 m, and a crude internal pseudo-stratigraphy. At the base of the root zone are isotropic ophitic gabbros interpreted as a thermal boundary layer. This layer is transitional between the magmatic system of the melt lens, convecting at 1200°C, and a high-temperature (<1100°C) hydrothermal system, convecting within the root zone. Above this level, the isotropic gabbros have been, locally, largely molten due to an influx of seawater, at $1100°C, thus generating varitextured ophitic and pegmatitic gabbros. These latter gabbros constitute the upper part of the root zone and are associated with trondjhemitic intrusions as screens in the lower sheeted dikes. Diorites and trondjhemites were also generated by hydrous melting, at temperatures below 1000°C. The whole root zone is a domain of very sharp average thermal gradient ($7°C/m). At the top of the root zone, a new thermal boundary layer, with diabase dikes hydrated in amphibolite facies conditions, separates the preceding high-temperature convective system from the well-known greenschist facies (<450°C) hydrothermal system operating throughout the sheeted dike complex, up to the seafloor. The isotropic gabbros near the base of the root zone are intruded by protodikes with distinctive microgranular margins and an ophitic center. Protodike swarms are exceptional because, intruding a medium at $1100°C, they are largely destroyed by dike-in-dike intrusions and by hydrous melting. However, they demonstrate that this zone was generated by melt conduits issued from the underlying melt lens. Each dike of the sheeted dike complex is thus fed by one protodike. As this zone has been recently drilled by IODP in the eastern Pacific Ocean, a brief comparison is proposed.

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Section: A1 Relation Between Water and Oxygen Fugacitymentioning

confidence: 99%

Root zone of the sheeted dike complex in the Oman ophiolite

Nicolas

Boudier

Koepke

et al. 2008

Geochem Geophys Geosyst

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“…To investigate whether the approach using the above formulation has extrapolative value, the model was also calibrated using only data with P <_ 3 kbar [Holtz et al, 1992[Holtz et al, , 1995 The formulation in (14) also reproduces very well the H20 solubility in rhyolitic melt (calculated curve 1 in Figure 7a), demonstrating its applicability to natural rhyolitic melts. Furthermore, the formulation also repro- Three leftmost columns are from Holtz et al [1992,1995]; fi-i2o is calculated from Pitzer and Sterner [1994]; XH2Om is calculated using equation (13) The H20 solubility in AOQ melt is determined at 700 ø-1350øC and has its best precision at high H20 t (and hence high P) because Karl-Fischer titration is used to obtain H2Ot, whereas the H20 speciation in rhyolitic glasses is determined at 400ø-600øC and the speciation model is calibrated only at -<2.4% H20 t. Combination of the two data sets to model solubility requires the extrapolation of the speciation model to much higher T and much higher H2Ot, which may be problematic and result in inaccuracy of f/melt Whatever the explanations, more r H2Om.…”

Section: H20 T In the Melt Divided By Fi-i•o) Depends On Fi-i•o-mentioning

confidence: 99%

“…Dissolved H20 in silicate melt affects its properties and evolution, such as viscosity [e.g., Shaw, 1963Shaw, , 1972Burnham, 1967;Stolper, 1982a [Shaw, 1963[Shaw, , 1974Silver et al, 1990;Ihinger, 1991], to calibrate the infrared technique [Newman et al, 1986;Ihinger et al, 1994;Zhang et al, 1997a], to examine the temperature dependence of speciation [Zhang et al, 1991a;Ihinger, 1991;Ihinger et al, 1999], to examine the reaction kinetics of the speciation reaction [Zhang et al, 1991a[Zhang et al, , 1995[Zhang et al, , 1997b, and to investigate water diffusion [Shaw, 1974;Zhang et al, 1991a]. bThis sample has a nominal composition of Qz28Ab38Or34 (where Qz means quartz, Ab means albite, and Or means orthoclase, KA1Si308) and has been used to investigate the temperature dependence of H20 solubility [Holtz et al, 1992[Holtz et al, , 1995, to examine the temperature dependence of speciation (H20 t = 4.14%) in an in situ study [Nowak and Behrens, 1995], and to study H20 diffusion .…”

Section: Introduction and Overviewmentioning

confidence: 99%

H₂O in rhyolitic glasses and melts: Measurement, speciation, solubility, and diffusion

Zhang¹

1999

Reviews of Geophysics

249

138

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Abstract. Dissolved H20 in silicate melts and glasses plays a crucial role in volcanic eruptions on terrestrial planets and affects glass properties and magma evolution. In this paper, major progress on several aspects of the H20-melt (or glass) system is reviewed, consistency among a variety of data is investigated, discrepancies are evaluated, and confusion is clarified. On the infrared measurement of total H20 and species concentrations, calibration for a variety of glasses has been carried out at room temperature. The measurements for H20 in rhyolitic glasses have undergone the most scrutiny, resulting in the realization that absorptivities for the near-infrared bands depend on total H20 content. Although the variation of the absorptivities does not seem to significantly affect the determination of total H20 , it does affect the determination of molecular H20 and OH species concentrations. Calibration of the infrared technique for H20 in rhyolitic glasses still needs much improvement, especially at high total H20. Furthermore, it is now almost certain that the molar absorptivities also depend on the measurement temperature in in situ studies. Hence it will be necessary to carry out calibrations in situ at high temperatures. On H20 speciation, results from two experimental approaches, the quench technique and the in situ technique, are very different, leading to controversy in our understanding of true speciation. A solution is presented to reconcile this controversy. It is almost certain that the quench technique does not suffer from a quench problem, but interpretation of in situ results suffered from ignoring the dependence of the molar absorptivities on measurement temperature. Accurate calibration at high temperatures is necessary for the quantitative application of the in situ technique to H20 speciation in silicate melts and glasses. On H20 solubility in silicate melts, recent experimental work has Significantly expanded the T-P range of solubility measurements, and recent solubility models fill a gap for predicting solubility for a wide range of melt compositions. I present a solubility model for rhyolitic and quasirhyolitic melts over a wide range of T and P (500 ø-1350øC, 0-8 kbar) by incorporating the role of speciation. The solubility model is able to recover the experimental solubility data and has extrapolative value, although the partial molar volume of H20 derived from the solubility model differs from that derived from density measurements. On H20 diffusion, recent studies on H20 diffusion in a quasi-rhyolitic melt at 800ø-1200øC, 0.5-5 kbar, and up to 7% total H20 not only provide important new diffusion data, but are also challenging earlier understanding of H20 diffusion based on data in rhyolitic glasses at 400ø-550øC, 1 bar, and 0.2-1.8% total H20. A comparison between the earlier model and recent data is made. The recent high-temperature diffusivities at total H20 -< 2% can be predicted by the earlier model. However, at higher total H20 , the earlier model fails. New work is under way t...

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“…However, intrinsic uncertainties are associated with fluid-melt partitioning data from quench techniques, which make it problematic to obtain unambiguous data, particularly for the trace element concentration in the fluid. The uncertainties are related to (i) the difficulty of isolating the fluid phase for sampling and analysis, (ii) fluid unmixing and (iii) precipitation of solids during quenching, and possible back reactions between fluid and melt during cooling (Holtz et al, 1995;Adam et al, 1997;Behrens et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Partitioning and equilibration of Rb and Sr between silicate melts and aqueous fluids

et al. 2009

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Trace element concentrations in aqueous fluids in equilibrium with haplogranitic melt were determined in situ at elevated P-T conditions using hydrothermal diamond-anvil cells and synchrotron-radiation XRF microanalyses. Time-resolved analyses showed that the Rb and Sr concentrations in the fluids became constant in less than 2000 s at all temperatures (500 to 780°C). Although fluid-melt equilibration was very rapid, the change in the concentration of both elements in the fluid with temperature was fairly small (a slight increase for Rb and a slight decrease for Sr). This permitted partitioning data for Rb and Sr between haplogranitic melt and H 2 O or NaCl + KCl + HCl aqueous solutions at 750°C and 200 to 700 MPa to be obtained from EMP analyses of the quenched melt and the in situ SR-XRF analyses of the equilibrated fluid.

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H₂O solubility in haplogranitic melts; compositional, pressure, and temperature dependence

Cited by 293 publications

References 23 publications

Root zone of the sheeted dike complex in the Oman ophiolite

Root zone of the sheeted dike complex in the Oman ophiolite

H₂O in rhyolitic glasses and melts: Measurement, speciation, solubility, and diffusion

Partitioning and equilibration of Rb and Sr between silicate melts and aqueous fluids

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H2O solubility in haplogranitic melts; compositional, pressure, and temperature dependence

Cited by 293 publications

References 23 publications

Root zone of the sheeted dike complex in the Oman ophiolite

Root zone of the sheeted dike complex in the Oman ophiolite

H2O in rhyolitic glasses and melts: Measurement, speciation, solubility, and diffusion

Partitioning and equilibration of Rb and Sr between silicate melts and aqueous fluids

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H₂O solubility in haplogranitic melts; compositional, pressure, and temperature dependence

H₂O in rhyolitic glasses and melts: Measurement, speciation, solubility, and diffusion