Diffusion in rock alteration systems; I, Prediction of limiting equivalent ionic conductances at elevated temperatures

Nigrini, Andrew

doi:10.2475/ajs.269.1.65

Cited by 34 publications

(20 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Values of D vary with species as well as with pressure and temperature. However, they generally fall in the range 10 -5 cmZ/sec to 10 -3 cmZ/sec (Nigrini, 1970;Ildefonse and Gabis, 1976;Balashov et al, 1983;Brady, 1983). For our purposes, we can choose D = 10 -~ cmZ/sec, ~p = 0.001, 0 = 1.…”

Section: Ramentioning

confidence: 99%

See 1 more Smart Citation

Metamorphic reaction rate laws and development of isograds

Lasaga

1986

Mineral. mag.

114

View full text Add to dashboard Cite

A n S T R A C T. New data on the kinetics of dehydration o f muscovite+quartz suggest the necessity for a careful treatment of both surface kinetics and diffusion processes in metamorphic reactions. A new model is proposed that illustrates the relative role of diffusion and surface reactions in the overall metamorphic process. The rate law for the reaction at mineral surfaces derived from the experimental data is shown to be probably non-linear and similar to rate laws derived from Monte Carlo calculations. The experimental rate data is then used in a heat flow calculation to model the evolution of the muscovite isograd in the field. The position of the isograd, the temperature oversteps above equilibrium, and the width of 'reaction zones' are then analysed as a function of intrusion size and kinetic parameters.KEYWORDS: metamorphic reactions, surface kinetics, diffusion, rate laws. THE fOCUS of metamorphic petrology today is shifting from a static mode based on the thermodynamics of mineral assemblages to a dynamic mode aimed at the quantification of the processes that produced the metamorphism. As a result, the non-equilibrium aspects and the kinetics of metamorphic processes are being increasingly studied. The proper role of equilibrium versus kinetics in describing metamorphism is still being debated today. As petrologists initially tackled the complexities of the texture and mineralogy of metamorphic rocks, many of which could not coexist according to an equilibrium model, the concept of local equilibrium (Thompson, 1959;Helgeson, 1968; Fisher and Elliott, 1974) was born. In this fashion, equilibrium was maintained at least on a local scale, which meant essentially for surfaces of mineral grains in physical contact with each other. Isotope studies (Lattanzi et al., 1980; Rumble et al., 1982;Rumble and Spear, 1983;Tracy et al., 1983) have investigated the length scale of equilibrium and found many cases where it was only a few centimetres.Closer inspection of the chemical composition of minerals has unearthed a wide variety of zoning profiles which preserve, albeit encoded by the ~) Copyright the Mineralogical Societykinetics, the details of the metamorphic history. The ubiquitous zoning found in several metamorphic minerals has led to recent papers on their kinetic significance (Lasaga et al., 1977;Lasaga, 1983;Ozawa, 1984;Smith and Ehrenberg, 1984;Wilson andSmith and Wilson, 1985; Docka et al. (in press).More recently, the kinetic study has been extended to the generation, motion and characterization of metamorphic fluids. Within the assumption of local equilibrium, it was logical to assume that the local mineral assemblage would control or buffer the composition of the fluid phase during dehydration/hydration and decarbonation/ carbonation reactions and that the kinetics were fast enough to be ignored. This control, however, can only be achieved by the continuous and concurrent dissolution and growth of one or several minerals. As Greenwood (1975) has shown, the amount of fluid involved during evolution...

show abstract

Section: Ramentioning

confidence: 99%

“…One important distinction between L o and D~j should be stated. The size of D~ in 'fluids' is generally restricted over a couple of orders of magnitude (10-s to 10-3 cm2/sec) over the metamorphic range of P and T (Nigrini, 1970). However, for a tracer (Fisher and Lasaga, 1981):…”

Section: Kinetics Of Metamorphic Fluid-rock Reactionsmentioning

confidence: 99%

Metamorphic reaction rate laws and development of isograds

Lasaga

1986

Mineral. mag.

114

View full text Add to dashboard Cite

show abstract

“…There is a linear correlation between the limiting equivalent conductance, A O , and the standard partial molal entropy of ion at infinite dilution, So, (9.44) where the subscript i refers to a single ion, and the subscript j to a group of ions (cations and anions of like charge). The values of A?, and hence D?, for various ions (Oelkers and Helgeson, 1988a), calculated using a range of experimental data and Equation 9.44, superseded Nigrini's (1970) model.…”

Section: Tracer Diffusion Coefficients For Ions and Ion Pairsmentioning

confidence: 99%

“…Developing ideas by Wishaw and Stokes (1954), Nigrini (1970) proposed a method to calculate the tracer diffusion coefficients for ion pairs from Os for individual species. In that method, an ion pair is represented as a spherical ellipsoid with an equatorial diameter equal to the largest species diameter, and a major axis equal in length to the sum of the species diameters.…”

Section: Tracer Diffusion Coefficients For Ions and Ion Pairsmentioning

confidence: 99%

Diffusion of electrolytes in hydrothermal systems: free solution and porous media

Balashov¹

1994

Fluids in the Crust

View full text Add to dashboard Cite

“…Smoothed profiles are likely because non-smoothed profiles require diffusive fluxes from lithologic units with high concentrations to those with low concentrations. Based on ion diffusion coefficients that are about 30 times greater at 275°C than at 2°C (Nigrini, 1970), calculated chemical fluxes resulting from differences in chemical concentrations between lithologic units that are thin, typically less than 10 m thick, are large enough to impact the concentration in the solid phase. However, the solid phase does not record such fluxes (Goodfellow and Peter, this volume).…”

Section: Major Ionsmentioning

confidence: 99%

A Technique for Obtaining Pore-Water Chemical Composition from Indurated and Hydrothermally Altered Sediment and Basalt: The Ground Rock Interstitial Normative Determination (Grind)

Wheat¹,

Boulègue²,

Mottl³

1994

Proceedings of the Ocean Drilling Program, 139 Scientific Results

View full text Add to dashboard Cite

During Ocean Drilling Program Leg 139 at Middle Valley, Juan de Fuca Ridge, we recovered indurated sediment and hydrothermally altered diabases and gabbros from an active hydrothermal reservoir at Sites 857 and 858. Because few of these samples yielded pore water upon squeezing even at the maximum pressure afforded by the hydraulic presses aboard JOIDES Resolution, we developed the GRIND technique (ground rock interstitial normative determination). The GRIND technique consists of fragmenting a freshly collected sample, grinding the sample with distilled water in a ball mill, squeezing the ground mixture, and analyzing the effluent.Concentrations of Mg, Ca, Na, K, Rb, and, from Site 857 only, Sr, measured in GRIND samples are comparable to measurements of squeezed samples, in contrast to alkalinity, sulfate, dissolved silica, Ba, Mn, Li, and B, which differ substantially between the two methods. GRIND samples with chlorinity greater than about 100 mmol/kg have only minimal artifacts caused by ion exchange. Ion exchange in more diluted pore-water samples causes an increase in Na and a decrease in Mg, Ca, and Sr. The GRIND method could be an invaluable tool for estimating the chemical composition of pore waters in basement.

show abstract

Diffusion in rock alteration systems; I, Prediction of limiting equivalent ionic conductances at elevated temperatures

Cited by 34 publications

References 0 publications

Metamorphic reaction rate laws and development of isograds

Metamorphic reaction rate laws and development of isograds

Diffusion of electrolytes in hydrothermal systems: free solution and porous media

A Technique for Obtaining Pore-Water Chemical Composition from Indurated and Hydrothermally Altered Sediment and Basalt: The Ground Rock Interstitial Normative Determination (Grind)

Contact Info

Product

Resources

About