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 May 1980 | public
Journal Article

Phase relations and their petrological implications in the system MgO-SiO_2-H_2O-CO_2 at pressures up to 100 kbar

Abstract

A comprehensive model has been developed for phase relations in the system MgO-SiO_2-H_2O-CO_2 on the basis of Schreinemakers' rules and subsolidus thermodynamic data. The assemblage forsterite plus enstatite can 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 magnesite at intermediate pressures, and at a vapor-absent eutectic at high pressures. Forsterite and H_2O-CO_2 vapor cannot coexist at pressures greater than 90 kbar. A thermal maximum is postulated to exist on the reaction Fo + En + V → L at pressures greater than 35 kbar. Thermal maxima on vapor-present melting reactions may be responsible for the eruption of kimberlitic magma from the upper mantle.

Additional Information

© 1980 Mineralogical Society of America. Manuscript received, April 9, 1979; accepted for publication, January 15, 1980. This research was supported by NSF grant EAR 76-20410 (Earth Sciences Section).

Additional details

Created:
August 22, 2023
Modified:
October 17, 2023