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Melting relationships in the systems CaO-CO_2 and MgO-CO_2 to 33 kilobars

Huang, Wuu-Liang and Wyllie, Peter J. (1976) Melting relationships in the systems CaO-CO_2 and MgO-CO_2 to 33 kilobars. Geochimica et Cosmochimica Acta, 40 (2). pp. 129-132. ISSN 0016-7037. doi:10.1016/0016-7037(76)90169-1.

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The melting temperatures of calcite and magnesite in the presence of excess CO_2 have been measured using Ag_2C_2O_4 in sealed capsules m a piston-cylinder apparatus. At 27 kbar, 11.5 wt % CO_2 dissolves in molten CaCO_2, depressing the freezing temperature from 1610 to 1505°C; and 6.5 wt % CO_2 dissolves in molten MgCO_3, depressing the freezing temperature from 1590 to 1510°C. The eutectic between calcite and lime was located at 1385°C at 27 kbar. These and other new results, combined with previously published data, permit completion of PT diagrams for the systems CaO-CO_2 and MgO-CO_2 from 1 bar to 35 kbar. The dissociation curve for each carbonate terminates at an invariant point where melting begins, at 40 bars and 1230°C for CaO-CO_2 and 23 kbar and 1550°C for MgO-CO_2 The differences between the two systems are explained by the different solubilities of CO_2 in the invariant liquids consequent upon the large pressure difference between the locations of these two invariant points. The results show that the temperatures for the beginning of melting of carbonates in the asthenosphere are lowered by about 100°C in the presence of CO_2.

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Alternate Title:Melting relationships in the systems CaO-CO2 and MgO-CO2 to 33 kilobars
Additional Information:© 1976 Elsevier Ltd. Received 8 April 1975; accepted in revised form 17 June 1975. This research was supported by the Earth Sciences Section. National Science Foundation. NSF Grant GA-41730. We would like to acknowledge also the general support of the Materials Research Laboratory by the National Science Foundation.
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Official Citation:Huang Wuu-Liang, Peter J. Wyllie, Melting relationships in the systems CaOCO2 and MgOCO2 to 33 kilobars, Geochimica et Cosmochimica Acta, Volume 40, Issue 2, February 1976, Pages 129-132, ISSN 0016-7037, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64067
Deposited By: Tony Diaz
Deposited On:28 Jan 2016 23:35
Last Modified:10 Nov 2021 23:25

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