Cordierite and wollastonite-bearing rocks of south-western Ceylon

Abstract

SUMMARY In the region east of the south-western belt of Ceylon, garnet is stable in biotite-bearing pelitic rocks which belong to the hornblende-granulite subfacies. In the south-western belt, which includes Zone B of the eastern part of the Gampaha sheet, garnet is unstable in biotite-bearing pelitic rocks, garnet reacting with biotite to produce cordierite which has a widespread occurrence in the belt to which it is confined. To accommodate the stable cordierite-bearing pelitic assemblages the erection of a cordierite-granulite subfacies is necessary. Wollastonite-bearing rocks, which commonly occur in the belt and are confined to it, belong to the cordierite-granulite subfacies.