Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published 1979 | Published
Book Section - Chapter Open

A model of phase relations in the system MgO-SiO_2-H_2O-CO_2 and prediction of the compositions of liquids coexisting with forsterite and enstatite

Abstract

A comprehensive model has been developed for the system MgO-SiO_2-H_2O-CO_2 on the basis of experimental studies, Schreinemaker's rules, and thermodynamic data. The assemblage forsterite plus enstatite is predicted to melt in the presence of vapor of any H_2O/CO_2 ratio at low pressures, in the presence of vapor whose H_2O/CO_2 ratio is buffered by the presence of magnesite at intermediate pressures, and at a vapor-absent eutectic with brucite and magnetite at high pressures. The composition of the liquid at the solidus for a bulk composition of forsterite plus enstatite plus a small amount of volatiles with a 3/1 H_2O/CO_2 ratio changes from enstatite-quartz normative at 20 kbar, to periclase- forsterite normative at 50 kbar, to forsterite-enstatite normative at 90 kbar and greater pressures. Forsterite cannot coexist with H_2O-CO_2 vapor at pressures greater than 90 kbar. Thus all melting in the earth's mantle at higher pressures must be vapor-absent.

Additional Information

© 1979 American Geophysical Union. This research was supported by the Earth Sciences Section, National Science Foundation, NSF Grant EAR 76-20410.

Attached Files

Published - Wyllie_1979p313.pdf

Files

Wyllie_1979p313.pdf
Files (2.0 MB)
Name Size Download all
md5:393aa8ded28f590aa4a74b54b2f57b6d
2.0 MB Preview Download

Additional details

Created:
August 22, 2023
Modified:
October 18, 2023