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Competition between Na_2SO_4 and Na sulfide in the upper crust of Io

Burnett, D. S. (1995) Competition between Na_2SO_4 and Na sulfide in the upper crust of Io. Journal of Geophysical Research E, 100 (E10). pp. 21265-21270. ISSN 0148-0227. doi:10.1029/95JE01165.

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The Na atmosphere of Io requires a Na-S-O phase in the outer surface layers. Considering the various mechanisms for extraction of Na to the surface, the possible primary phases are Na_2O, Na_2S_x and Na_2SO_4. However, regardless of the primary phases brought to the surface, the shallow crustal recycling of material implied by the ongoing volcanism will tend to produce thermochemical equilibrium and cause all Na to end up as Na_2SO_4 or Na_2S_x. This hypothesis is investigated by relatively model-independent thermodynamic calculations. The major assumption is that material is statistically circulated to sufficiently high temperatures by burial that thermochemical equilibrium can be attained. For a wide range of assumed crustal (PT) conditions, Na_2O will be converted to Na_2SO_4. During residence in the shallowest crustal regions dominated by liquid SO_2, e.g., SO_2 geysers or fumaroles, or for any crustal regimes where SO_2 and S are in comparable abundances, Na-sulfides will be converted to Na_2SO_4. However, in high-temperature, low-pressure regimes with a low relative abundance of SO_2 relative to S (e.g., due to outgasing of SO_2), Na_2SO_4 is converted to Na sulfides. Such regimes could be relatively common on Io, e.g., associated with flows, lava lakes, or shallow intrusions. Consequently, because of thermochemical equilibration in different crustal environments, both Na_2SO_4 and Na sulfides will coexist on the Io surface.

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Burnett, D. S.0000-0001-9521-8675
Alternate Title:Competition between Na2SO4 and Na sulfide in the upper crust of Io
Additional Information:Copyright 1995 by the American Geophysical Union. (Received November 9, 1994; revised April 3, 1995; accepted April 6, 1995.) Paper number 95JE01165. I gratefully acknowledge important thermodynamic discussions with John Beckett, and manuscript reviews by Fraser Fanale and Douglas Nash. This research was supported by Planetary Materials and Geochemistry grant NAGW 3534. Caltech contribution 5523.
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Caltech Division of Geological and Planetary Sciences5523
Issue or Number:E10
Record Number:CaltechAUTHORS:20141106-091042367
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Official Citation:Burnett, D. S. (1995), Competition between Na2SO4 and Na sulfide in the upper crust of Io, J. Geophys. Res., 100(E10), 21265–21270, doi:10.1029/95JE01165.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51349
Deposited By: George Porter
Deposited On:06 Nov 2014 18:05
Last Modified:10 Nov 2021 19:09

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