Silicate facies iron-formation of the Egbe-lsanlu Palaeoproterozoic schist belt, southwest Nigeria
No Thumbnail Available
Date
1997
Authors
ANNOR, A.E
Olobaniyi, S.B
MUCKE, A
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of African Earth Sciences
Abstract
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.
Description
Keywords
iron-formation , petrological , mineralogical , geochemical , silicates
Citation
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.