Indian Journal of Geo-Marine Sciences

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The Occurrence of Phosphorites on the Calicut Mount, off Kerala, Lakshadweep Sea, India


Affiliations
1 Marine and Coastal Survey Division, Geological Survey of India, Pandeshwar, Mangalore, Karnataka – 575 001, India

A highly altered carbonate rock was recovered from the mount, off Calicut, Kerala. Bulk chemical analysis of the rock showed that it contains ∼ 21 % P2O5. The rock consists of fine to coarse lithic and bio-clasts embedded in brown to the yellow coloured phosphatic matrix. Detailed SEM-EDS of the rock piece indicates micro-globular and nodular growth of phosphorite around calcite to form a core-rim structure, with P2O5 as high as 31.67 weight percentage. The X-ray elemental mapping carried out using EPMA indicates highest P2O5 (29.87 %) on the altered surfaces. Microstructural and geochemical analyses suggest authigenic/diagenetic precipitation of phosphorite on the carbonate rock.
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  • The Occurrence of Phosphorites on the Calicut Mount, off Kerala, Lakshadweep Sea, India

Abstract Views: 268  | 

Authors

B. Gopakumar
Marine and Coastal Survey Division, Geological Survey of India, Pandeshwar, Mangalore, Karnataka – 575 001, India
A. Anil Kumar
Marine and Coastal Survey Division, Geological Survey of India, Pandeshwar, Mangalore, Karnataka – 575 001, India
S. K. Sardar
Marine and Coastal Survey Division, Geological Survey of India, Pandeshwar, Mangalore, Karnataka – 575 001, India

Abstract


A highly altered carbonate rock was recovered from the mount, off Calicut, Kerala. Bulk chemical analysis of the rock showed that it contains ∼ 21 % P2O5. The rock consists of fine to coarse lithic and bio-clasts embedded in brown to the yellow coloured phosphatic matrix. Detailed SEM-EDS of the rock piece indicates micro-globular and nodular growth of phosphorite around calcite to form a core-rim structure, with P2O5 as high as 31.67 weight percentage. The X-ray elemental mapping carried out using EPMA indicates highest P2O5 (29.87 %) on the altered surfaces. Microstructural and geochemical analyses suggest authigenic/diagenetic precipitation of phosphorite on the carbonate rock.