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Carbonation of peridotites and decarbonation of siliceous dolomites represented in the system CaO-MgO-SiO_2-CO_2 to 30 kbar

Wyllie, P. J. and Huang, W.-L. and Otto, Jens and Byrnes, A. P. (1983) Carbonation of peridotites and decarbonation of siliceous dolomites represented in the system CaO-MgO-SiO_2-CO_2 to 30 kbar. Tectonophysics, 100 (1-3). pp. 359-388. ISSN 0040-1951. https://resolver.caltech.edu/CaltechAUTHORS:20160120-151840565

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Abstract

The decarbonation of siliceous dolomite produces rocks including the minerals forsterite, orthopyroxene and clinopyroxene, characteristic of peridotites. Selected reactions in the system CaO-MgO-SiO_2 –CO_2 are reviewed and published data at crustal and mantle pressures are compared with previously unpublished experimental results between 15 and 30 kbar for five reactions: (0) magnesite + clinopyroxene = dolomite + orthopyroxene; (1) magnesite + quartz = enstatite + CO_2; (5) dolomite + orthopyroxene + quartz = clinopyroxene + CO_2; (3) magnesite + enstatite = forsterite + CO_2; (6) dolomite + orthopyroxene = clinopyroxene + forsterite+ CO_2. Reactions (0), (1) and (5) meet at an invariant point near 1090°C and 34 kbar. Reactions (3) and (6) represent the carbonation of model harzburgite and Iherzolite, respectively. Dolomites in reaction (6) contain more than 70 wt.% CaCO_3, at temperatures below the crest of the calcite-dolomite solvus, they are magnesian calcites. Phase relationships for carbonated model peridotites in the presence of H_2O, compared with estimated depths and temperatures of equilibration of xenoliths from the Premier Mine kimberlite, indicate that within limited depth intervals solid magnesite-harzburgite can coexist with partially melted lherzolite. Eruption of kimberlite could transport xenoliths of Iherzolite and magnesite-harzburgite. Experiments indicate that the magnesite dissociates within minutes during uprise. This observation is consistent with the proposal of Boyd and Gurney that low-calcium garnets in kimberlites of the Kaapvaal-Rhodesian craton are produced by disruption of magnesite disseminated through depleted harzburgites in the roots of the craton, within the diamond stability field.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/0040-1951(83)90194-4DOIArticle
http://www.sciencedirect.com/science/article/pii/0040195183901944PublisherArticle
Alternate Title:Carbonation of peridotites and decarbonation of siliceous dolomites represented in the system CaO-MgO-SiO2-CO2 to 30 kbar
Additional Information:© 1983 Elsevier B.V. Revised version received by Publisher December 2, 1983. This research was supported by a series of grants from the Earth Sciences Section of the National Science Foundation, most recently EAR-8108599 and EAR-8311758. We thank Dr. RC. Newton for discussions and experimental consultations.
Funders:
Funding AgencyGrant Number
NSFEAR-8108599
NSFEAR-8311758
Issue or Number:1-3
Record Number:CaltechAUTHORS:20160120-151840565
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20160120-151840565
Official Citation:P.J. Wyllie, W.-L. Huang, Jens Otto, A.P. Byrnes, Carbonation of peridotites and decarbonation of siliceous dolomites represented in the system CaO-MgO-SiO2-CO2 to 30 kbar, Tectonophysics, Volume 100, Issues 1–3, December 1983, Pages 359-388, ISSN 0040-1951, http://dx.doi.org/10.1016/0040-1951(83)90194-4. (http://www.sciencedirect.com/science/article/pii/0040195183901944)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63810
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:21 Jan 2016 19:25
Last Modified:03 Oct 2019 09:31

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