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Authors
Affiliations
1 DB-12, Sector-I, Salt Lake City, Calcutta 700 064, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 36, No 1 (1990), Pagination: 46-53
Abstract
The phosphate occurs as discontinuous patches forming massive compact claystone-like rocks. Submicroscopic grains of quartz, feldspar and flakes of mica, and grains of cryptocrystalline rock fragments and chert occur in a phosphatised ground mass. Coarsely crystalline calcite and siderite of secondary origin are commonly associated. The cores of nodular masses show altered. olivine, pyroxene, prismatic calcic plagioclase, rock and chert fragments, and vein-quartz in a coarsely crystalline carbonate cement, while the outer shells of the nodular bodies are of amorphous phosphatic material. Trace-element analyses show high values of Ba, Y, and La in phosphatic rocks compared to non-phosphatic ones. An igneous source for the clasts in the cores of nodular bodies and secondary phosphatisation through late hydrothermal solutions are suggested.
Keywords
Phosphatic Rock, Gondwana, Ib River Coal Field, Coal, Sundergarh Dt. Orissa.
