Mineral Chemistry of Mafic Clotsin Putteti Alkaline Suite, Kanyakumari District, Tamil Nadu, India

Abstract

Putteti is a well-known alkaline suite south of Achankovil Shear Zone in Southern Granulite Terrain (SGT). This intrusive is quite famous for the ubiquitous zircon megacrysts, and various sulphides and oxides. Syenite and pyroxenite, with textural and compositional diversity, form the major intrusive phases of this suite. They occur as alternate magmatic layers where pyroxenes form cumulates. Clots or segregates of pyroxenes are alsonoticedin the syenite. The amount of pyroxene in syenite varies considerably. Earlier workers explained this phenomenon as due to liquid immiscibility of a single magma. The temperature, composition and rheology of the original melt play a major role in deciphering the texture and mineralogy of the resultant rocks. Mineral chemistry helps to infer the thermal history of the members of the suite and the sequence of crystallization. Here we present thechemical data of pyroxenes in syenite and hybrid rock that help to establish the interrelationships of the members of the suite and their evolution.