Geochemistry of Trondhjemites from Sigegudda, Hassan District, Karnataka

The Sigegudda trondhjemites contain moderate Zr, high Ni and Cr and therefore appear to have formed by partial melting and/or fractional crystallization of Ni- and Cr-rich rocks like amphibolites. Lack of fractionation of Y, Zr and TiO₂ and comparatively lower LREE/HREE ratio in these rocks perhaps indicate that garnet was not present in the magma source. The trondhjcmites were probably emplaced during the stabilization of the western Dharwar craton around 3.0 b.y. ago.