A Comparative Study of the Chakradharpur and the Arkasani Granite Gneiss, Singhbhum District, Bihar

The Arkasani granite gneiss occurs as detached elongate outcrops close to the northern margin of the Chakradharpur granite gneiss. Both show imprints of the same deformation and same textural and structural characters. While the Chakradharpur gneiss ranges from tonalite - granodiorite - granite - alkali feldspar granite, the Arkasani gneiss is an alkali feldspar granite. Major element compositions of the two are either gradational or overlapping. The former has higher Na₂O values and the latter higher K₂O values. The two groups of gneisses are genetically related.