Metastable corundum + quartz + andalusite association in pelitic granulite from the Kerala Khondalite Belt, southern India

Abstract

Corundum in direct contact with quartz and associated with andalusite has been found as an inclusion in alkali feldspar obtained from a leucosome, which forms a part of migmatized pelitic granulite from the Kerala Khondalite Belt, southern India. Thermodynamically, corundum + quartz is metastable relative to andalusite. Textural features suggest that it is a rare example of an arrested reaction corundum + quartz → andalusite which may have been triggered off by the introduction of H 2O-rich fluids along the cracks of the host alkali feldspar during the uplift and cooling of the leucosome. The metastable corundum + quartz association most likely originated during the crystallization of the Al 2O 3-rich leucosome melt when early corundum came into contact with later quartz under conditions with a relatively low H 2O activity.