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A lirst report on tuff beds from the Owk Shale in the Proterozoic Kurnool sub-basin in southern India is presented.The rhvolitic lo ihodacitic tuffs,overlying shclfal limestones formed at depths below storm wave base,have rheomorphic features indicative of viscoplaslic flow.and geochemical signatures of rhvolitic to rhyodacitic unwekled to welded tuffs,similar to those described from other Proterozoic intracratonie basins like Vindhvan and Chhattisgarh basins in India.Fragmentary naiure of altered glass with perlitic cracks and local admixture with intrabasinal sediments suggest phreatomagmatic reactions.The widespread and repealed occurrences of felsic luffs in these basins.possibly derived from low degree melting of continental crust.suggest intermittent(ectonothermal instability which likely intluenced hasinal topography and cyclic development of the carbonate platforms.
A first report on tuff beds from the Owk Shale in the Proterozoic Kurnool sub-basin in southern India is presented. The rhvolitic lo ihodacitic tuffs, overlying shclfal limestones formed at depths below storm wave base, have rheomorphic features indicative of viscoplaslic flow. And geochemical signatures of rhvolitic to rhyodacitic unwekled to welded tuffs, similar to those described from other Proterozoic intracratonie basins like Vindhvan and Chhattisgarh basins in India. Fragmentary naiure of altered glass with perlitic cracks and local admixture with intrabasinal sediments suggest phreatomagmatic reactions. widespread and repealed occurrences of felsic luffs in these basins. postsib derived from low degree melting of continental crust.suggest intermittent (ectonothermal instability which likely contributed to hasinal topography and cyclic development of the carbonate platforms.