Dharwar Stratigraphy

Reconsideration of the stratigraphy of the Dharwars of Mysore State in the light of new data suggests that they are Paleoproterozoic and overlie Charnockites of Archean age. Classification of Dharwars based on tectonomagmatic and atmospheric evolution leads to a four fold divison. Pregeosynclinal shelf stage iS represented by two cycles of platformal sedimentation and magmatism; the earlier, under oxygen deficient conditions, on mafic platforms built by subaerial lavas, Is represented by Bababudan Series, and the latter under oxygenic conditions accompained by alkaline ultramafic intrusions gave rise to Dodguni Series. The geosynclinal Stage represented by pillow-Iava-greywacke-Iron ore deposition (third cycle of magmatism and sedimentation) constitutes the Grey trapRambennur Series. Early tectonic plagioclase granites-Champion gneisses syntectonic migmatites-Peninsular gneisses and late to post-tectonic alkali metasomatic granites Closepet granites (fourth, fifth and sixth magmatic cycles) developed during the folding and metamorphism of Dharwar geosynclinal pile. The inversion of geosyncline witnessed apogeosynclinal molasse red bed Sedimentation (fourth cycle of sedimentation) represented by G. R. Series. Paleoproterozoic epidiorites and post-Paleoproterozoic dolerites cratonised the area.