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Calculated mineral reactions in the Earth's mantle

Ahrens, Thomas J. and Syono, Yasuhiko (1967) Calculated mineral reactions in the Earth's mantle. Journal of Geophysical Research, 72 (16). pp. 4181-4188. ISSN 0148-0227.

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Thermochemical and compressibility data are used to calculate the approximate pressures and temperatures required for the reaction of clinoenstatite to Mg_2SiO_4 (spinel or olivine) or to periclase and stishovite, the reaction of forsterite to Mg_2SiO_4 (spinel) or periclase and stishovite, and the breakdown of Mg_2SiO_4 (spinel) to periclase and stishovite. The calculated reaction lines for Mg_2SiO_4 (olivine) → 2 MgO + SiO_2 and MgSiO_3 → MgO + SiO_2 are p = 199±17 + 0.021T and p = 182±17 + 0.024T (p in kilobars and T in degrees Celsius). These reaction lines lie at higher pressures than previously estimated. Because of the formation of Mg_2SiO_4 (spinel) these two reactions probably do not take place in the earth's mantle. It appears, rather, that the reactions Mg_2SiO_4 (olivine) → Mg_2SiO_4 (spinel), Mg_2SiO_4 (spinel) → 2 MgO + SiO_2, and 2 MgSiO_3 → Mg_2SiO_4 (spinel) + SiO_2 take place along p = 110±11 + 0.024T, p = 321±38 − 0.013T, and p = 133±19 + 0.039 T, respectively.

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Additional Information:Copyright 1967 by the American Geophysical Union. (Received September 16, 1966; revised March 27, 1967.) We appreciate the help of Dr. E. G. King of the Berkeley Thermodynamics Laboratory for bringing several thermochemical studies to our attention. The National Science Foundation provided support for one of us (Y.S.) under grant GP 5422.
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NSFGP 5422
Issue or Number:16
Record Number:CaltechAUTHORS:20141107-162252871
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Official Citation:Ahrens, T. J., and Y. Syono (1967), Calculated mineral reactions in the Earth's mantle, J. Geophys. Res., 72(16), 4181–4188, doi:10.1029/JZ072i016p04181.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51470
Deposited By: George Porter
Deposited On:10 Nov 2014 16:16
Last Modified:03 Oct 2019 07:33

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