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Water diffusion in a basaltic melt

Zhang, Youxue and Stolper, E. M. (1991) Water diffusion in a basaltic melt. Nature, 351 (6324). pp. 306-309. ISSN 0028-0836. http://resolver.caltech.edu/CaltechAUTHORS:20120827-074155979

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Abstract

Water is the most abundant volatile component in terrestrial basalts and is a significant constituent of the gases that escape from basaltic magmas. Knowledge of the diffusivity of water (and other volatiles) in basaltic melts is important for understanding the degassing of basaltic magma and for assessing the fractionation of volatiles during degassing. We report here measurements of water diffusivity in a basaltic liquid. The water concentration profiles through the samples, determined by Fourier-transform infrared spectroscopy, cannot be modelled adequately on the basis of a constant water diffusivity, but instead can be fitted by assuming that only molecular H_2O is diffusing and that there is a local equilibrium between H_2O molecules and OH groups. The concentration-dependent total water diffusivities in the basaltic melt at 1,300–1,500 °C are 30–50 times as large as those in rhyolitic melts, and are greater than the total CO_2 diffusivity in basaltic melts, contrary to previous expectations. These results suggest that diffusive fractionation would increase the ratio of water to carbon dioxide in growing bubbles relative to equilibrium partitioning, and decrease the ratio in interface melts near an advancing anhydrous phenocryst.


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http://dx.doi.org/10.1038/351306a0DOIUNSPECIFIED
http://www.nature.com/nature/journal/v351/n6324/abs/351306a0.htmlPublisherUNSPECIFIED
Additional Information:© 1991 Nature Publishing Group. Received 27 December 1990, accepted 10 April 1991. We thank M. R. Carroll for comments and S. van der Laan for providing the JDF glasses; Y. Z. thanks M. B. Baker for technical assistance. This work is supported by NSF and NASA.
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Record Number:CaltechAUTHORS:20120827-074155979
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20120827-074155979
Official Citation:Water diffusion in a basaltic melt 306 Youxue Zhang & E. M. Stolper doi:10.1038/351306a0
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:33539
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:27 Aug 2012 15:17
Last Modified:27 Aug 2012 15:17

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