The mafic and ultramafic rocks in Odhimalai, Thenkalmalai, Tittamalai hills of late Archean Bhavani complex are found in the districts of Coimbatore and Erode, Tamilnadu (India). The field characteristics of this area mostly dark color, coarse graind with the mafic minerals being dominated by pyroxene, gabbro, amphibole and garnet. The Cauvery Shear Zone (CSZ) represents prominent Archaean–Proterozoic boundary in Southern Granulite Terrain (SGT) and exposes the highest-grade granulites of a prograde amphibolite facies to granulite facies deep-crystal section of Late Archaean age. The rock show a granoblastic polygonal micro-texture and disequilibrium textures mostly in metagabbroic rocks, containing garnet. The petrographic study of thin section related that the rocks are rich in with medium grained hornblende crystals. This descriptions of the lithologies reveal the mineral content micro-textural relationship between the grains and deformational as well as alteration structures. The pyroxenite and gabbro showed consistent and complementary composition of SiO2 ranging from 26.21% to 50.12%, Al2O3 ranging from 8.63% to 25.57 %, MgO ranging from 6.83% to 26.64 %, CaO ranging from 4.67% to 14.23%, P2O5 ranging from 0.03% to 0.16 %.
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