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Authors
Affiliations
1 Department of Geology, University of Delhi, Delhi 110 007, IN
2 Wadia Institute of Himalayan Geology 33, General Mahadeo Singh Road, Debra Dun, U.P., IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 32, No 1 (1988), Pagination: 32-39
Abstract
Stromatolitic and pelletal phosphorite deposits, belonging to Cumbum Subgroup of Nallamalai Group have recently been reported from Chelima-Pachcherla areas of Kurnool district in Andhra Pradesh. Most phosphorites of these areas are linked to the carbonate stromatolites like other Proterozoic phosphorite deposits of India. However, there are many variants which occur amidst quartzose rocks, assuming pel1etal forms, showing well marked neomorphic grain-growths and marked enrichment of elements like F, K2O, Ba, Co, Mn, V, Y and Pb. Based on mineralogy, petrology, and geochemistry of these phosphorites, a protected-isolated supratidal lagoon type of environment has been visualised for the precipitation and diagenetic alteration of the Cumbum phosphorite.
