Published online by Cambridge University Press: 01 May 2009
Quartz–microperthite–hornblende–garnet–plagioclase granulites belonging to the Highland Series of Ceylon are described. The invariable presence of accessory graphite suggests their metasedimentary origin and their chemical composition indicates a possible derivation from feldspathic sandstones. Although the mineral assemblage of these granulites is diagnostic for the upper almandine–amphibolite facies, they are interlayered with orthopyroxene-bearing charnockites of the granulite facies. It is concluded that PHO was initially higher in the sandstones than in the surrounding rocks, and that it remained so during metamorphism under granulite facies conditions, thereby retarding the dehydration reactions that took place elsewhere in the vicinity.