Geochemistry and Origin of Northern Closepet Granite from Gudur-Guledagudda Area, Bagalkot District, Karnataka

The late Archaean Closepet Granite of the Gudur-Guledagudda area consists of equigranular pink and grey biotite granites, and porphyntic pink biotite granodionte to quartz-monzodionte. The granitoids exhibit intrusive relation with the Hungund-Kushtagi schist belt at places. The equigranular granites show limited range of major oxide compositions and compared to the porphyntic granodionte and quartz-monzodionte, are enriched in Si0₂, K₂0 and Rb but depleted in Al₂0₃, FeO, Fe₂0₃, CaO, MgO, P₂0₅, Sr, Ba, Y, Nb and REE. The granitoids fall near the boundary between peraluminous and metaluminous granitoids with the A/CNK ratios around one Fractionated LREE and flat HREE patterns and a negative Eu anomaly characterize all the samples Field evidences indicate mainly post-kinematic nature of the granitoids. The equigranular granites appear to be minimum melt derived from anatexis of Peninsular Gneiss without fractional crystallization. The porphyntic granodionte and quartz-monzodionte represent non-minimum melt derived from a different source enriched in REE Geochemical signatures indicate that the Closepet Granite of Gudur-Guledagudda area is the product of melting at shallower level compared to the southern Closepet Granite.