Major oxide chemical analysis and petrography of granite from Chityala area were carried out to decipher crustal evolution and to estimate the mineralogical composition. These studies reveal that the original magmatic structures have been completely obliterated, because of the onset of subsequent petrogenetic processes. Further, replacement structures and textural intergrowth of perthite and myrmekite are commonly observed. Orthoclase is partially altered and indicating that in the older rocks it will be altering into microcline coupled with exsolution melt around the myrmekite grain boundaries. Harkar's variation diagram shows increasing the SiO2 along with other oxides like TiO2, MgO, P2O5, Al2O3 CaO that decrease in this rock. Al2O3/CaO+Na2O+K2O vs Al2O3/Na2O show weak to moderate peraluminous to a metaluminous nature of this granite in the investigated area. Ab-An-Or diagram depicts most of the samples as a cluster in granitic field. Few samples contain low amount of silica and plot close to the boundary of granite and granodiorite.
Petrography, geochemistry, granites, granodiorite
