Mineral equilibria in the system nepheline-alkali feldspar-plagioclase and their petrological significance

Journal of Petrology
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Abstract

The purpose of this work is a theoretical consideration of equilibrium conditions in the system nepheline-alkali feldspar-plagioclase-alkali chloride aqueous solution based on the thermodynamic treatment of experimental data (Orville, 1963; Iiyama et al., 1963; Debron et al., 1961) for particular systems. The excess thermodynamic functions (ZE, SE, HE, VE) of solid solutions were calculated for it. These data enable us to derive the diagrams of isotherms for the distribution of sodium components between nepheline and alkali feldspar; between plagioclase and alkali feldspar; and among plagioclasenepheline, and alkali feldspar for the temperature range 400-1000° C.In order to check the calculated diagrams we analysed the minerals from the binary and ternary assemblages of the systems nepheline$alkali feldspar$plagioclase from various igneous massifs of nepheline syenites of the world. Temperatures obtained from different geothermometers were found to coincide satisfactorily.

Publication type Article
Publication Subtype Journal Article
Title Mineral equilibria in the system nepheline-alkali feldspar-plagioclase and their petrological significance
Series title Journal of Petrology
DOI 10.1093/petrology/9.1.123
Volume 9
Issue 1
Year Published 1968
Language English
Publisher Oxford University Press
Description 45 p.
First page 123
Last page 167
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