Abstract
Optical and SEM observations of phosphorites reveal that mineralization is concentrated on ooids and micro-oncoids. The coated grains occur within microbial mats. Microbial mats represent the formational environment of the ooids and oncoids. Both coated grains and mats exhibit similar filamentous micro-organisms. The mat filaments show no fixed orientation and they merge with the concentrically oriented filaments of the coated grains. The branching nature and chlamydospore-like structures of filaments suggest that both mat and coated grains have been formed by fungi. Some coated grains appear to have been slightly disturbed and sometimes mobilized from their sites of formation due to separation from the parent mat resulting perhaps from contraction/fragmentation. The voids so created within the mat had been later filled with either micrite or sparite.
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References
Axelrod, S., Rohrlich, V.: Chemical variability in francolites from Israeli phosphorite macrograins. Mineralium Deposita 17:1–15 (1982)
Banerjee, D.M., Basu, P.C., Srivastava, R.N.: Petrology, mineralogy, geochemistry, and origin of the Precambrian Aravallian phosphorite deposits of Udaipur and Jhabua, India. Economic Geology 75:1181–1199 (1980)
Baturin, G.N.: The stages of phosphorite formation on the ocean floor. Nature 232:61–62 (1971)
Bremner, J.M.: Concretionary phosphorite from SW Africa. J. Geol. Soc. 137:773–786 (1980)
Burnett, W.C.: Geochemistry and origin of phosphorite deposits from off Peru and Chile. Bull. Geol. Soc. Amer. 88:813–823 (1977)
Burnett, W.C.: Apatite-glauconite association off Peru and Chile: palaeo-oceanographic implications. J. Geol. Soc. 137:757–764 (1980)
Champetier, Y., Joussemet, R.: Decouverte de Nubeculaires et d'oncolithes en tant qu'elements phosphates. Com. Rend. Acad. Sci. Paris A 288:673–675 (1979)
Champetier, Y., Blazy, P., Joussemet, R.: Enrichissement des phosphates carbonates. Caracterisation gitologique et petrographique. Comportement au traitement thermique. 2e Congres international sur les composes phosphores, 283–312 (1980)
Cheney, TM., McClellan, G.H., Montgomery, E.S.: Sechura phosphate deposits, their stratigraphy, origin, and composition. Economic Geology 74:232–259 (1979)
Folk, R.L.: Practical petrographic classification of limestones. Bull. Amer. Assoc. Petrol. Geol. 43:1–38 (1959)
Hamdadou, M.: Regards Nouveaux sur les aspects petro-mineralogiques des Phosphates de Djebel-Onk. Industrie Minerale — Les Techniques. 570–573 (1983)
Horton, A., Ivimey-Cook, H.C., Harrison, R.K., Young, B.R.: Phosphatic öoids in the Upper Lias (Lower Jurassic) of central England. J. Geol. Soc. 137:731–740 (1980)
Howard, P.F., Hough, M.J.: On the geochemistry and origin of the D-Tree, Wonarah, and Sherrin Creek phosphorite deposits of the Georgina Basin, Northern Australia. Economic Geology 74:260–284 (1979)
Kolodny, Y.: Lithostratigraphy of the Mishash Formation, Northern Negev. Israel Journal of Earth-Sciences 16:57–73 (1967)
Krumbein, W.E.: Photolithotrophic and chemoorganotrophic activity of bacteria and algae as related to beachrock formation and degradation (Gulf of Aqaba, Sinai). Geomicrobiology Jour. 1:139–203 (1979)
Krumbein, W.E.: Stromatolites — The challenge of a term in space and time. Precambrian Research 20:493–531 (1983)
Lamboy, M.: Importance des pelotes fecales comme origin des grains de phosphate: l'exemple du gisement de Gafsa (Tunisie). C.R. Acad. Sci. Paris 295, Ser. 2, 595–600 (1982)
Lucas, J., Prevot, L.: Synthese de l'apatite par voie bacterienne a partir de matiere organique phosphatee et de divers carbonates de calcium dans des eaux douce et marine naturelles. Chem. Geol. 42:101–118 (1984)
Lucas, J., Prevot, L., Trompette, R.: Petrology, mineralogy and geochemistry of the late Precambrian phosphate deposits of Upper Volta (W Africa). J. Geol. Soc. 137:787–792 (1980)
Riggs, S.R.: Phosphorite sedimentation in Florida — A model phosphogenic system. Economic Geology 74:285–314 (1979)
Soudry, D., Champetier, Y.: Microbial processes in the Negev phosphorites (Southern Israel). Sedimentology 30:411–423 (1983)
Soudry, D., Nathan, Y.: Phosphate peloids from the Negev phosphorites. J. Geol. Soc., 137:749–755 (1980)
Veeh, A.W., Calvert, S.E., Price, N.B.: Accumulation of Uranium in sediments and phosphorites on the South West African shelf. Mar. Chem. 2:189–202 (1974)
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Dahanayake, K., Krumbein, W.E. Ultrastructure of a microbial mat-generated phosphorite. Mineral. Deposita 20, 260–265 (1985). https://doi.org/10.1007/BF00204283
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DOI: https://doi.org/10.1007/BF00204283