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Studies in synthetic carbonatite systems: Solidus relationships for CaO-MgO-CO_2-H_2O to 40 kbar and CaO-MgO-SiO_2-CO_2-H_2O to 10 kbar

Boettcher, A. L. and Robertson, J. K. and Wyllie, P. J. (1980) Studies in synthetic carbonatite systems: Solidus relationships for CaO-MgO-CO_2-H_2O to 40 kbar and CaO-MgO-SiO_2-CO_2-H_2O to 10 kbar. Journal of Geophysical Research B, 85 (B12). pp. 6937-6943. ISSN 0148-0227. doi:10.1029/JB085iB12p06937. https://resolver.caltech.edu/CaltechAUTHORS:20141105-143853050

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Abstract

The system CaO-MgO-SiO_2-CO_2-H_2O is an important model for many igneous and metamorphic processes, including the generation and differentiation of carbonatite and associated silicate magmas. We have experimentally established the vapor-saturated solidus for the system CaO-MgO-CO_2-H_2O from 595°C/1 kbar to <500°C/40 kbar, about 25°C lower than the corresponding temperatures for the CaO-CO_2-H_2O system. Brucite replaces periclase on the vapor-saturated solidus at about 750 bars pressure, remaining as the stable phase to pressures of at least 40 kbar; no dolomite or magnesite was encountered. At a pressure between 35 and 40 kbar, the assemblage portlandite + brucite + aragonite + vapor changes to one containing phase W, a previously unreported Ca-Mg carbonate. At 20 kbar, the vapor-saturated liquid contains at least 24 wt % H_2O. The vapor-saturated solidus for the system CaO-MgO-SiO_2-CO_2-H_2O ranges from 613°C/1 kbar to 565°C/10 kbar, experimentally indistinguishable from that for CaO-MgO-CO_2-H_2O, about 10°C lower than that for CaO-CO_2-H_2O, and about 25°C lower than that for CaO-SiO_2-CO_2-H_2O. In the quinary system, monticellite is replaced by dellaite and an unidentified silicate on the vapor-saturated solidus above 4.1 kbar. MgO-poor liquids are similar in composition to the magma from which the Magnet Cove calcite carbonatite crystallized. More magnesian magmas would produce dolomite at moderate depths, such as at Alnö Island.


Item Type:Article
Related URLs:
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http://dx.doi.org/10.1029/JB085iB12p06937DOIArticle
http://onlinelibrary.wiley.com/doi/10.1029/JB085iB12p06937/abstractPublisherArticle
Alternate Title:Studies in synthetic carbonatite systems: Solidus relationships for CaO-MgO-CO2-H2O to 40 kbar and CaO-MgO-SiO2-CO2-H2O to 10 kbar
Additional Information:Copyright 1980 by the American Geophysical Union. (Received March 20, 1980; revised April 22, 1980; accepted May 9, 1980.) Paper number 80B0707. A. Gaines assisted us by determining the lattice parameters of the synthetic aragonites. I. S. McCallum kindly analyzed the synthetic aragonites with the electron microprobe. The manuscript was critically reviewed by Robert C. Newton. This work was supported by NSF grants GA-923 and EAR76-20410 to P. J. Wyllie and GA-1364 and EAR78-16413 to A. L. Boettcher. Institute of Geophysics and Planetary Physics, University of California, Los Angeles, contribution 1865.
Funders:
Funding AgencyGrant Number
NSFGA-923
NSFEAR76-20410
NSFGA-1364
NSFEAR78-16413
Other Numbering System:
Other Numbering System NameOther Numbering System ID
UCLA Institute of Geophysics and Planetary Physics1865
Issue or Number:B12
DOI:10.1029/JB085iB12p06937
Record Number:CaltechAUTHORS:20141105-143853050
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20141105-143853050
Official Citation:Boettcher, A. L., J. K. Robertson, and P. J. Wyllie (1980), Studies in synthetic carbonatite systems: Solidus relationships for CaO-MgO-CO2-H2O to 40 kbar and CaO-MgO-SiO2-CO2-H2O to 10 kbar, J. Geophys. Res., 85(B12), 6937–6943, doi:10.1029/JB085iB12p06937.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51331
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:06 Nov 2014 21:09
Last Modified:10 Nov 2021 19:09

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