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The system CaO-SiO_2-CO_2-H_2O: 1. Melting relationships with excess vapor at 1 kilobar pressure

Wyllie, P. J. and Haas, J. L., Jr. (1965) The system CaO-SiO_2-CO_2-H_2O: 1. Melting relationships with excess vapor at 1 kilobar pressure. Geochimica et Cosmochimica Acta, 29 (8). pp. 871-892. ISSN 0016-7037. https://resolver.caltech.edu/CaltechAUTHORS:20160112-091148681

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Abstract

Solid-liquid-vapor phase equilibria have been determined for parts of the system CaO-SiO_2-CO_2-H_2O by delineating the phase fields intersected by the composition join CaCO_3-Ca(OH)_2-(SiO_2 + 4.3 weight per cent H_2O) at 1 kilobar pressure between 600°C and 975°C. The phases encountered were: dicalcium silicate (C_2S), Ca_2SiO_4; calcite (CC), CaCO_3; portlandite (CH), Ca(OH)_2; spurrite (Sp), Ca_5(SiO_4)_2(CO_3)_2; caleiochondrodite (Ch), Ca_5(SiO_4)_2(OH)_2; liquid (L), with composition remaining close to the plane Ca_2SiO_4-CaCO_3-Ca(OH)_2; vapor (V), with composition ranging between CO_2 and H_2O. At the pressure of 1 kilobar, the following ternary univariant reactions, (2) and (3), and quaternary univariant reactions, (6), (7) and (8). were established at the temperatures indicated: (2) CH + Ch + V ⇌ L(E_2) at 774 ± 10°C; (3) Ch + V ⇌ C_2S + L(P_3) at 955 ± 10°C; (6) CC + CH + Ch + V ⇌ L(E_6) at 637 ± 10°C; (7) CC + Ch + V ⇌ Sp + L(P_7) at 677 ± 10°C; (8) Sp + Ch ⇌ C_2S + L(P_8) + V at 860 ± 10°C. The vapor in each reaction is high in H_2O content. From these results and other published data a schematic equilibrium diagram for the whole system is constructed. A large field for spurrite extends down to 677°C on the vapor-saturated liquidus surface but wollastonite is not stable in equilibrium with both liquid and vapor below 1000°C at this pressure. The plane Ca_2SiO_4-CO_2-H_2O is a thermal divide; original liquids containing more SiO_2 than this plane yield only silicates and vapor on crystallization, whereas original liquids containing less SiO_2 than this plane can yield low temperature liquids precipitating hydrated and carbonated phases (synthetic carbonatite magmas). Applications to carbonatites and the thermal metamorphism of silicious limestones are discussed briefly.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/0016-7037(65)90084-0DOIArticle
http://www.sciencedirect.com/science/article/pii/0016703765900840PublisherArticle
Alternate Title:The system CaO-SiO2-CO2-H2O: 1. Melting relationships with excess vapor at 1 kilobar pressure
Additional Information:© 1965 Published by Elsevier Ltd. Contribution No. 64-39 from the College of Mineral Industries, The Pennsylvania State University, University Park, Pennsylvania. We would like to thank D. M. Roy for her help and advice during the study, and for a critical review of the manuscript, and the National Science Foundation for their support of the work. The research was supported by Grant G-19588 in 1961-1962, and preparation costs were covered by Grant GP-1870.
Funders:
Funding AgencyGrant Number
NSFUNSPECIFIED
NSFG-19588
NSFGP-1870
Issue or Number:8
Record Number:CaltechAUTHORS:20160112-091148681
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20160112-091148681
Official Citation:P.J Wyllie, J.L Haas Jr., The system CaO-SiO2-CO2-H2O: 1. Melting relationships with excess vapor at 1 kilobar pressure, Geochimica et Cosmochimica Acta, Volume 29, Issue 8, August 1965, Pages 871-892, ISSN 0016-7037, http://dx.doi.org/10.1016/0016-7037(65)90084-0. (http://www.sciencedirect.com/science/article/pii/0016703765900840)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63574
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:12 Jan 2016 19:00
Last Modified:03 Oct 2019 09:29

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