Reaction Textures in Silica-Deficient Granulites of Ganguvarpatti, Madurai District, Tamil Nadu

Abstract

The silica-deficient granulites of Ganguvarpatti display textural evidences of metamorphic reactions, involved in the formation of diverse mineral assernblagest documented by different types of reaction coronas and symplectitic intergrowths. The symplectitic intergrowths, viz., orthopyroxene-spinel-cordierite and orthopyroxene-spinel-cordierite-sapphirine rimming corroded garnet have been attributed to reactions:

Gt + H₂O⇋Opx + Sp + Cd

Gt + O₂ + H₂O⇋Opx + Sp + Cd + Sa

The textural relation of orthopyroxene isolated from sapphirine by a reaction corona of cordierite + spinet is related to reaction: Opx +Sa + H₂O⇋Cd + Sp.