Fugacity coefficients for hydrogen gas between O degrees and 1000 degrees C, for pressures to 3000 atm

Shaw, Herbert R.; Wones, David R.

doi:10.2475/ajs.262.7.918

Cited by 106 publications

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“…The coefficient γ H2O is from Holland and Powell (1991), γ H2 is from Shaw and Wones (1964), and the other coefficients are from Shi and Saxena, (1992). The gas is thus considered as an ideal mixture of real pure gases.…”

Section: Summary Of the Chemical Modelmentioning

confidence: 99%

Simulating the behavior of volatiles belonging to the C–O–H–S system in silicate melts under magmatic conditions with the software D-Compress

Burgisser

Alletti

Scaillet

2015

Computers & Geosciences

103

125

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a b s t r a c tModeling magmatic degassing, or how the volatile distribution between gas and melt changes at pressure varies, is a complex task that involves a large number of thermodynamical relationships and that requires dedicated software. This article presents the software D-Compress, which computes the gas and melt volatile composition of five element sets in magmatic systemsIt has been calibrated so as to simulate the volatiles coexisting with three common types of silicate melts (basalt, phonolite, and rhyolite). Operational temperatures depend on melt composition and range from 790 to 1400°C. A specificity of D-Compress is the calculation of volatile composition as pressure varies along a (de)compression path between atmospheric and 3000 bars. This software was prepared so as to maximize versatility by proposing different sets of input parameters. In particular, whenever new solubility laws on specific melt compositions are available, the model parameters can be easily tuned to run the code on that composition. Parameter gaps were minimized by including sets of chemical species for which calibration data were available over a wide range of pressure, temperature, and melt composition. A brief description of the model rationale is followed by the presentation of the software capabilities. Examples of use are then presented with outputs comparisons between D-Compress and other currently available thermodynamical models. The compiled software and the source code are available as electronic supplementary materials.

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Section: Summary Of the Chemical Modelmentioning

confidence: 99%

Simulating the behavior of volatiles belonging to the C–O–H–S system in silicate melts under magmatic conditions with the software D-Compress

Burgisser

Alletti

Scaillet

2015

Computers & Geosciences

103

125

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“…Then, based on the fO 2 determined from the phenocryst assemblage (c.NN O^1·5, White et al, 2009), we calculate the corresponding fH 2 , using the water dissociation equilibrium as explained above. The fugacity coefficients of H 2 O and H 2 at P and T are from Burnham et al( 1 9 6 9 ) and Shaw & Wones (1964), respectively. A magma with 4 wt % dissolved H 2 Oat7 308C and 150 MPa and NNO1…”

Section: Fluid Phase: Inferences On Its Presence and Compositionmentioning

confidence: 99%

Phase Equilibrium Constraints on Pre-eruptive Conditions of Recent Felsic Explosive Volcanism at Pantelleria Island, Italy

Carlo

Rotolo

Scaillet

et al. 2010

Journal of Petrology

130

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We present experimental phase equilibria carried out on a pantelleritic bulk-rock composition with a peralkalinity index [PI INTRODUCTIONPantelleria island is the type-locality of pantellerite, an iron-and sodium-rich peralkaline rhyolite. Pantellerites, by far the most abundant rock-type at Pantelleria, occur as pyroclastic flows, pumice fall deposits, or as obsidianaceous lavas (Mahood & Hildreth, 1986). After the Plinian eruption of the Green Tuff (45 ka BP), and the related caldera collapse, resurgent felsic magmatism was mainly centered inside the caldera, producing either low-energy explosive eruptions or lava flows.Recent experimental investigations (Scaillet & Macdonald, 2001 and melt inclusion studies (Kovalenko et al., 1988;Webster et al., 1993;Wilding et al Barclay et al., 1996;Gioncada & Landi, 2010) have shown that peralkaline melts may be rather H 2 O-rich, in contrast to previous inferences. These studies have also demonstrated the role of pressure, water, oxygen fugacity, and silica and sodium disilicate activity (aSiO 2 , aNds) on the phase equilibria of felsic peralkaline magmas from the east Kenyan rift zone (e.g. Scaillet & Macdonald, 2001Caricchi et al., 2006). In this study we present the hydrous phase equilibria of a pantellerite with a peralkalinity index PI [ ¼ molar (Na 2 O þ K 2 O)/Al 2 O 3 ] ¼ 1·4, established within the pressure range 25^150 MPa, for temperatures between 680 and 8008C, with oxygen fugacities below the Ni^NiO solid buffer (NNO), and melt water contents (H 2 O melt ) up to 6 wt %. We apply our experimentally derived P^TĤ 2 O melt grid to natural pantellerites to assess the pre-eruptive conditions (T, P,H 2 O melt )ofthemostpowerful event of the post-caldera period, the Fastuca eruption (Orsi et al.,1989). Knowledge of the pre-eruptive conditions sheds light on the nature of the magmatic plumbing system associated with recent felsic volcanism at Pantelleria, with several obvious implications for the eruptive style of pantellerite magmas. The determination of magma storage conditions of pantelleritic magmas can also provide constraints on the more general problem of the origin of silica-oversaturated peralkaline magmas, which has been extensively debated (see Bohrson & Reid, 1997;Civetta et al., 1998;Marshall et al., 1998;Marshall et al. 2009;Scaillet & Macdonald, 2001;Nekvasil et al., 2004;Macdonald et al., 2008). Much of the controversy has arisen because of the lack of modern phase equilibrium constraints for peralkaline magmas, in contrast to their metaluminous or peraluminous counterparts (e.g. Dall' Agnol et al., 1999;Klimm et al., 2003;Bogaerts et al., 2006). GEOLOGICAL AND PETROLOGICAL BACKGROUNDPantelleria (Italy) is an entirely volcanic island ( Fig. 1) located within the Sicily Channel continental rift system, in the northern part of the African plate (e.g. Rotolo et al., 2006). Pantelleria is well known in the petrological literature because its eruptive products represent a typical bimodal suite: a mafic end-member, which consists of mildly alkali basalts, a...

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“…Oxygen fugacity, for experiments in which water activity (aH 2 O) was varied by the addition of CO 2 to the charges, can be evaluated using the following simple relationship (Scaillet & Evans, 1999 Further information about f O 2 can be found in Shaw & Wones (1963), Burnham et al (1969), Robie et al (1979) and Pownceby & O'Neill (1994).…”

Section: Oxygen Fugacitymentioning

confidence: 99%

Estimation of pre-eruptive magmatic water fugacity in the Phlegrean Fields, Naples, Italy

Fabbrizio¹,

Scaillet²,

Carroll³

2009

ejm

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We estimated the water fugacity (f H 2 O) in the trachytic magma of Phlegrean Fields using the biotite-magnetite-sanidine equilibrium. We confirm that the partly ionic model is the most appropriate to estimate annite activity (a annite ) for the experimental biotite. Crystallization experiments were carried out on a representative sample of trachytic Breccia Museo eruption, Naples, Italy. Experiments were performed in the temperature and pressure range of 725-870 °C and 50-200 MPa, and redox conditions ranging from NNO (nickel-nickel oxide) + 1 (±0.2) to FMQ (fayalite + magnetite + quartz). Most experiments were done under conditions of H 2 O saturation (P water = P total ). Few experiments were done using a mixed H 2 O-CO 2 fluid phase. The pre-eruptive fH 2 O of the Phlegrean Fields magma is estimated at 735 bars, which compares well with available melt inclusion constraints. Our results confirm that this geohygrometer can be used in any magmatic systems bearing the worked assemblage.

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Fugacity coefficients for hydrogen gas between O degrees and 1000 degrees C, for pressures to 3000 atm

Cited by 106 publications

References 0 publications

Simulating the behavior of volatiles belonging to the C–O–H–S system in silicate melts under magmatic conditions with the software D-Compress

Simulating the behavior of volatiles belonging to the C–O–H–S system in silicate melts under magmatic conditions with the software D-Compress

Phase Equilibrium Constraints on Pre-eruptive Conditions of Recent Felsic Explosive Volcanism at Pantelleria Island, Italy

Estimation of pre-eruptive magmatic water fugacity in the Phlegrean Fields, Naples, Italy

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