Calc-Granulites Around Manalur, South and North Arcot Districts, Tamil Nadu, India

The plagioclase - pyroxene - garnet rocks, occurring in the Manalur area, have been designated as 'meta-anorthosite' by Murthy (1959). The authors however, consider them as a member of meta-sedimentary group of Archaeans which have resulted from the metamorphism of calcareous sediments of varying compositions. Since there is a general misconception among some of the Indian petrologists, who consider these metasedimentary calcareous members as 'anorthosites', it is proposed to deal with these rock types, in order to show that they have no association with anorthosites, which are one of the members of the layered complex.