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Title: Energetics of melts from thermal diffusion studies. Final report

Abstract

Most processes in geology are a consequence at some level of the flow of energy or mass. Heat conduction and chemical diffusion are examples of two of these sorts of flows which are driven by temperature and chemical potential imbalances, respectively. In the general case these flows may be coupled so that, for instance, a temperature gradient may result in a flow of mass as well as heat. This effect in liquids was demonstrated by Soret (1879) and bears his name. In gases or solids the phenomenon is given the general name thermal diffusion. It was the purpose of this research program to examine the Soret effect in molten silicates under laboratory conditions. Results of these experiments are used to evaluate the form and quantitative values of many thermodynamic and kinetic properties of silicate melts over a range of temperature, pressure, and bulk composition. The author published a comprehensive review and synthesis with a microscopic theoretical explanation for the effect at low pressure in silicate liquids of geological interest. He conducted experimental investigations of molecular diffusion in the absence of a thermal gradient through experiments involving dissolution of solid silicates in molten silicate and interdiffusion of species between miscible silicatemore » liquids. Collectively these results enable the author to construct a more comprehensive model of molecular diffusion in magmatic liquids. He has applied this model to problems of magma mixing and crustal assimilation.« less

Authors:
Publication Date:
Research Org.:
Univ. of California, Dept. of Geology, Davis, CA (United States)
Sponsoring Org.:
USDOE Office of Energy Research, Washington, DC (United States)
OSTI Identifier:
290918
Report Number(s):
DOE/ER/14240-T6
ON: DE99001169; BR: KC0403020; TRN: AHC29901%%123
DOE Contract Number:
FG03-92ER14240
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: [1998]
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; PROGRESS REPORT; RESERVOIR FLUIDS; THERMAL DIFFUSION; SILICATE MINERALS; DISSOLUTION; MATHEMATICAL MODELS; MAGMA

Citation Formats

Lesher, C.E. Energetics of melts from thermal diffusion studies. Final report. United States: N. p., 1998. Web. doi:10.2172/290918.
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Lesher, C.E. Energetics of melts from thermal diffusion studies. Final report. United States. doi:10.2172/290918.
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Lesher, C.E. Tue . "Energetics of melts from thermal diffusion studies. Final report". United States. doi:10.2172/290918. https://www.osti.gov/servlets/purl/290918.
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@article{osti_290918,
title = {Energetics of melts from thermal diffusion studies. Final report},
author = {Lesher, C.E.},
abstractNote = {Most processes in geology are a consequence at some level of the flow of energy or mass. Heat conduction and chemical diffusion are examples of two of these sorts of flows which are driven by temperature and chemical potential imbalances, respectively. In the general case these flows may be coupled so that, for instance, a temperature gradient may result in a flow of mass as well as heat. This effect in liquids was demonstrated by Soret (1879) and bears his name. In gases or solids the phenomenon is given the general name thermal diffusion. It was the purpose of this research program to examine the Soret effect in molten silicates under laboratory conditions. Results of these experiments are used to evaluate the form and quantitative values of many thermodynamic and kinetic properties of silicate melts over a range of temperature, pressure, and bulk composition. The author published a comprehensive review and synthesis with a microscopic theoretical explanation for the effect at low pressure in silicate liquids of geological interest. He conducted experimental investigations of molecular diffusion in the absence of a thermal gradient through experiments involving dissolution of solid silicates in molten silicate and interdiffusion of species between miscible silicate liquids. Collectively these results enable the author to construct a more comprehensive model of molecular diffusion in magmatic liquids. He has applied this model to problems of magma mixing and crustal assimilation.},
doi = {10.2172/290918},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Dec 01 00:00:00 EST 1998},
month = {Tue Dec 01 00:00:00 EST 1998}
}
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Technical Report:
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DOI:  10.2172/290918
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  • Efforts are reported in the following areas: laboratory equipment (multianvils for high P/T work, pressure media, SERC/DL sychrotron), liquid-state thermal diffusion (silicate liquids, O isotopic fractionation, volatiles, tektites, polymetallic sulfide liquids, carbonate liquids, aqueous sulfate solutions), and liquid-state isothermal diffusion (self-diffusion, basalt-rhyolite interdiffusion, selective contamination, chemical diffusion).

  • ;
    The second year of this three year renewal has been used to continue data collection and analysis of thermal (Soret) diffusion in silicate liquid and explore the related process of thermal migration in subliquidus magmas. During the past year we have expanded our experimental capabilities for thermal gradient work by the construction of two new miniaturized piston-cylinder devices capable of 20kb. This has greatly alleviated the bottleneck on our existing facilities and has permitted us to undertake long term thermal diffusion experiments which have been prohibitive in the past. Data collection efforts have also been materially aided by advances inmore » thermal insulation in the pressure media outside our pressurized cylindrical heaters. BaCO/sub 3/ + 10%Cr/sub 2/O/sub 3/ is very effective in protecting the pressure vessel core from thermal deterioration with the result that the heater inside and outside diameters can be substantially increased. This permits several charges to be run simultaneously in an axisymmetric cluster around a double or triple junction thermocouple which can measure axial thermal gradients in situ. These thermal insulation and charge volume increase innovations also have been adapted in our on going studies of mineral-liquid element partitioning, silicate mineral dissolution and silicate liquid interdiffusion and should prove to be wide applicability and utility in other piston-cylinder laboratories, as well. 13 refs.« less

  • This research program characterizes diffusional mass transport in geological fluids in response to thermal, solubility and chemical gradients using tools of experimental petrology. Quantitative information is obtained on the thermodynamic and kinetic properties of multicomponent systems that are the basis for predictive models of chemical diffusion, mineral dissolution, and complexing in synthetic and natural silicate systems. Among the technical accomplishments related to establishing the UCD experimental petrology laboratory in the last year has been the design and construction of two compact piston-cylinder devices capable of achieving 40 kb using 1/2-in. pressure vessels (also capable of accommodating 3/4-in. vessels). These machinesmore » are now on-line and performing thermal diffusion experiments. In addition to establishing the new laboratory at UCD, the PI began studies of molecular diffusion in the absence of a thermal gradient with results published on the chemical and self diffusion of Sr and Nd in naturally-occurring silicate liquids, and self diffusivities of Si and O in basaltic liquid.« less

  • This research program characterizes mass transport by diffusion in geological fluids in response to thermal, solubility, and/or chemical gradients to obtain quantitative information on the thermodynamic and kinetic properties of multicomponent systems. Silicate liquids undergo substantial thermal diffusion (Soret) differentiation, while the response in sulfide, carbonate, and aqueous fluids to an imposed temperature gradient is varied. The experimental observations of this differentiation are used to evaluate the form and quantitative values of solution parameters, and to quantify ordinary diffusion coefficients, heats of transport, and activation energies of multicomponent liquids. The diffusion, solution, and element partition coefficients determined for these geologicalmore » fluids form a data base for understanding magmatic crystallization behavior and for evaluating geothermal, ore deposit, and nuclear waste isolation potentials.« less

  • This research program characterizes mass transport by diffusion in geological fluids in response to thermal, solubility, and/or chemical gradients to obtain quantitative information on the thermodynamic and kinetic properties of multicomponent systems. Silicate liquids undergo substantial thermal diffusion (Soret) differentiation, while the response in sulfide, carbonate, and aqueous fluids to an imposed temperature gradient is varied. The experimental observations of this differentiation are used to evaluate the form and quantitative values of solution parameters, and to quantify ordinary diffusion coefficients, heats of transport, and activation energies of multicomponent liquids. The diffusion, solution, and element partition coefficients determined for these geologicalmore » fluids form a data base for understanding magmatic crystallization behavior and for evaluating geothermal, ore deposit, and nuclear waste isolation potentials.« less