Silicate facies iron-formation of the Egbe-lsanlu Palaeoproterozoic schist belt, southwest Nigeria
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Journal of African Earth Sciences
Field, petrological, mineralogical and geochemical data on the Egbe-lsanlu Palaeoproterozoic schist belt are presented, high-lighting the main features of a silicate facies iron-formation, which hitherto had been described as a metamorphosed, impure sandstone. The iron-formation is relatively thin (max. 15 m) and concordantly interbedded with schistose, semi-pelitic, amphibolitic and talcose host rocks, with which it shares a common polyphase tectonometamorphic history. The last of these is the Pan-African overprint, during which time the iron-formation was locally silicified. The main constituent minerals are garnet (almandine-spessartine solid solution), amphibole (Mn and Ca bearing grunerite-cummingtonite solid solution), quartz and ilmenite. Magnetite was not observed. Geochemical data show that the iron-formation and metasediments are of different origins. The silicate facies iron-formation of lsanlu belongs to the Algoma-type and was derived by the metamorphism of a volcano-exhalative-sedimentary protolith, probably during Eburnian times.
iron-formation , petrological , mineralogical , geochemical , silicates
Annor, A. E., Olobaniyi, S. B., & Mücke, A. (1997). Silicate facies iron-formation of the Egbe-Isanlu Palaeoproterozoic schist belt, southwest Nigeria. Journal of African Earth Sciences, 24(1-2), 39-50.