The Kunduru Betta Ring Intrusion, Malavalli, Karnataka, South India

Abstract

Field evidence is presented which allows the syenitic and granitic rocks occurring at Kunduru Betta to be reinterpreted as a ring intrusion. The syenitic rocks were intruded first and are divided into three major types based upon their field, textural and mineralogical characteristics which may be related to the conditions of crystallization.

Crystallization began with saturated syenite and ended with markedly silica oversaturated Quartz syenite. The granitic stock in the centre of the complex clearly crosscuts the syenitic rocks and is itself cut by later aplite dykes which also extend into the syenite and the country rocks. Both the syenite and the granite display lithological and sub-vertical mineralogical layering which is described for the first time.