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Title: Experimental study of radium partitioning between anorthite and melt at 1 atm

Abstract

We present the first experimental radium mineral/melt partitioning data, specifically between anorthite and a CMAS melt at atmospheric pressure. Ion microprobe measurement of coexisting anorthite and glass phases produces a molar D{sub Ra} = 0.040 {+-} 0.006 and D{sub Ra}/D{sub Ba} = 0.23 {+-} 0.05 at 1400 C. Our results indicate that lattice strain partitioning models fit the divalent (Ca, Sr, Ba, Ra) partition coefficient data of this study well, supporting previous work on crustal melting and magma chamber dynamics that has relied on such models to approximate radium partitioning behavior in the absence of experimentally determined values.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
940494
Report Number(s):
UCRL-JRNL-229336
Journal ID: ISSN 0003-004X; AMMIAY; TRN: US0807146
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: American Mineralogist , vol. 92, no. 8-9, August 1, 2007, pp. 1535-1538; Journal Volume: 92; Journal Issue: 8-9
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 07 ISOTOPES AND RADIATION SOURCES; 38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; ANORTHITE; ATMOSPHERIC PRESSURE; GLASS; MAGMA; MELTING; RADIUM; STRAINS

Citation Formats

Miller, S, Burnett, D, Asimow, P, Phinney, D, and Hutcheon, I. Experimental study of radium partitioning between anorthite and melt at 1 atm. United States: N. p., 2007. Web. doi:10.2138/am.2007.2640.
Miller, S, Burnett, D, Asimow, P, Phinney, D, & Hutcheon, I. Experimental study of radium partitioning between anorthite and melt at 1 atm. United States. doi:10.2138/am.2007.2640.
Miller, S, Burnett, D, Asimow, P, Phinney, D, and Hutcheon, I. Thu . "Experimental study of radium partitioning between anorthite and melt at 1 atm". United States. doi:10.2138/am.2007.2640. https://www.osti.gov/servlets/purl/940494.
@article{osti_940494,
title = {Experimental study of radium partitioning between anorthite and melt at 1 atm},
author = {Miller, S and Burnett, D and Asimow, P and Phinney, D and Hutcheon, I},
abstractNote = {We present the first experimental radium mineral/melt partitioning data, specifically between anorthite and a CMAS melt at atmospheric pressure. Ion microprobe measurement of coexisting anorthite and glass phases produces a molar D{sub Ra} = 0.040 {+-} 0.006 and D{sub Ra}/D{sub Ba} = 0.23 {+-} 0.05 at 1400 C. Our results indicate that lattice strain partitioning models fit the divalent (Ca, Sr, Ba, Ra) partition coefficient data of this study well, supporting previous work on crustal melting and magma chamber dynamics that has relied on such models to approximate radium partitioning behavior in the absence of experimentally determined values.},
doi = {10.2138/am.2007.2640},
journal = {American Mineralogist , vol. 92, no. 8-9, August 1, 2007, pp. 1535-1538},
number = 8-9,
volume = 92,
place = {United States},
year = {Thu Mar 08 00:00:00 EST 2007},
month = {Thu Mar 08 00:00:00 EST 2007}
}
  • Oxygen isotope partitioning between gaseous CO{sub 2} and a natural rhyolitic glass and melt (77.7 wt% SiO{sub 2}, 0.16 wt% H{sub 2}O{sub total}) has been measured at 550-950{degrees}C and approximately 1 bar. Equilibrium oxygen isotope fractionation factors ({alpha}{sub CO2-rhyolite} = ({sup 18}O/{sup 16}O){sub rhyolite}) determined in exchange experiments of 100-255 day duration. These values agree well with predictions based on experimentally determined oxygen isotope fractionation factors for CO{sub 2}-silica glass and CO{sub 2}-albitic glass/melt, if the rhyolitic glass is taken to be a simple mixture of normative silica and alkali feldspar components. The results indicate that oxygen isotope partitioning inmore » felsic glasses and melts can be modeled by linear combinations of endmember silicate constituents. Rates of oxygen isotope exchange observed in the partitioning experiments are consistent with control by diffusion of molecular H{sub 2}O dissolved in the glass/melt and are three orders of magnitude faster than predicted for rate control solely by diffusion of dissolved molecular CO{sub 2} under the experimental conditions. Additional experiments using untreated and dehydrated (0.09 wt% H{sub 2}O{sub total}) rhyolitic glass quantatively support these interpretations. We conclude that diffusive oxygen isotope exchange in rhyolitic glass/melt, and probably other polymerized silicate materials, it controlled by the concentrations and diffusivities of dissolved oxygen-bearing volatile species rather than diffusion of network oxygen under all but the most volatile-poor conditions. 25 refs., 6 figs., 1 tab.« less
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