Geochemistry of the Phyllites of the Copper Mountain Region, Sandur Schist Belt, Karnataka

Chemical composition of the phyllites of the Copper Mountain region of the late Archaean Sandur Schist belt in the eastern block of the Dharwar craton indicates that the fine-grained clastic sediments from which they were formed, were derived from a provenance comprising -60% felsic, - 30% mafic and 10% ultramafic rocks. High Zr/Nb and Zr/Y ratios and lack of strong -ve Eu anomalies suggest that the felsic component of the provenance was dominantly made up of tonalites-trondhjemites; granites and granodiorites were very subordinate constituents. The sediments appear to have accumulated in a continental island are environment. Rarity of granitic constituents in the pre-Dharwar provenance of Sandur basin contrasts with the abundance of such constituents in the provenance for the fine-grained clastic sediments of basins in the western block of the Dharwar craton. The continental crust of the eastern block was apparently less evolved during the pre-Dharwar time as compared to that in the western block of the Dharwar craton.