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Published December 1971 | public
Journal Article

Melting relations of NaAlSi_3O_8 to 30 Kb in the presence of H_2O:CO_2 = 50:50 vapor

Abstract

Synthetic albite was reacted with oxalic acid dihydrate under oxidizing conditions in an internally-heated pressure vessel from 1 to 4 kb and in a piston-cylinder apparatus from 10 to 30 kb. Breakdown of the oxalic acid in subsolidus runs produced a vapor with H_2O:CO_2 = 50:50 in moles (X^v_(H_2O) = 0.5, neglecting solubility of solids in the vapor). The curve determined for the beginning of melting under these conditions defines a contour on the divariant solidus surface for the system NaAlSi_3O_8-H_2O-CO_2 for X^v_(H_2O) = 0.5, between the published limits for X^v_(H_2O) = 1.0 and X^v_(H_2O) = O. Addition of 50 mole percent of relatively insoluble CO_2 to NaAlSi_3O_8-H_2O at 15 kb total pressure raises the solidus temperature from 660° to 830°C. The results give no indication of increased solubility of CO_2 in NaAlSi_3O_8 liquids at pressures above 15 kb, in contrast with published results for a basalt liquid.

Additional Information

© 1971 American Journal of Science. We thank the National Science Foundation for support from grants GA-15718 and GA-1110, the Advanced Research Products Agency for the piston-cylinder apparatus, Dr. J. K. Robertson for helpful discussions during the course of the experiments, and Drs. A. L. Boettcher and R. C. Newton for critical reviews of the manuscript.

Additional details

Created:
August 23, 2023
Modified:
October 17, 2023