Structural ordering of feldspars as an indikator of the temperature of mineralogenesis

The processes of albite ordering in the range of low temperatures 500–150°Cat a pressure of 0.5–1 kbar in alkaline solutions of sodium hydroxide with an excess of silica have been experimentally studied.Based on the data of our experiments and literature data on the ordering of albites and felsic plagioclases, dependences have been derived that make it possible to estimate the temperature from the degree of their structural ordering.The temperatures for plagioclase-bearing parageneses of various natural complexes of the greenschist facies of metamorphism have been determined.