Mineralium Deposita

, Volume 31, Issue 1–2, pp 113–122 | Cite as

The Algoma-type iron-formations of the Nigerian metavolcano-sedimentary schist belts

  • A. Mücke
  • A. Annor
  • U. Neumann


Field relationships as well as petrographical and geochemical considerations form the basis of a model for the origin of the protoliths of the iron-formations and the associated phyllitic host rock of the Palaeoproterozoic schist belts of northern Nigeria. The iron-formations which consist of both the magnetite-subfacies and silicatefacies occur as relatively small, sporadic tabular bodies throughout the belts. They are concordantly interbanded with metasedimentary phyllites with which they share common metamorphic and deformational imprints. The iron-formations have high contents of Mn, Ca, Fe and P2O5 and low concentrations of alkalis (Na,K, Rb) Ba and Sr, Ti, Al and Si, whereas the phyllite exhibits exactly the opposite character. These results and other features (e.g. the composition of tourmaline in the phyllite and the occurrence of hydroclastic Cr-Mn-spinel and sulphides in the iron-formation) indicate a supply of materials from two different sources to the marine basin of Nigeria probably during Birimian time: slow but continuous deposition of continentally derived material of pelitic to psammitic composition; and rapid, sometimes intermittent, sporadic pulses of submarine-volcanic exhalations. During regional metamorphism (probably of Eburnian age) at greenschist to lower amphibolite fades conditions, the continental materials were transformed into phyllites and the mudstone-like sediments derived from volcanic exhalations into iron-formations. In the northern Nigerian schist belts two types of metamorphic parageneses in the iron-formations are recognized, both with various subtypes and without transitions between these two facies: (1) silicate-rich parageneses without magnetite (silicatefacies) and (2) magnetite-rich parageneses (magnetite-subfacies). In contrast to these parageneses, the iron-formations in the higher-grade metamorphic terrains of central Nigeria turn out to be hematitic (hematite-subfacies), and are derived from magnetite-bearing iron-formations by a second tectono-metamorphic event of Pan-African age (Mücke and Annor 1993). Whole-rock analyses of the Nigerian iron-formations explain the abundance of garnet (mainly spessartine) and clearly show that the formation of metamorphic minerals depended not only on temperature and pressure but also on the existing redox conditions. These environmental conditions controlled the formation of either magnetite parageneses (low redox conditions) or silicate parageneses without magnetite (high redox conditions). The environmental conditions are also an indication that magnetite (and hematite) could not have been constituents of the original sedimentary protolith of the Nigerian schist belts, but are exclusively of metamorphic origin.


Nigeria Tourmaline Schist Belt Metamorphic Origin Metamorphic Terrain 
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  1. Ayres, D.E. (1972) Genesis of iron-bearing minerals in banded iron formation mesobands in the Dales Gorge Member, Hammersley Group. Western Australia Econ. Geol. 67:1214–1233Google Scholar
  2. Baur, M.E., Hayes, J.M., Studley, S.A., Walker, M.R. (1985) Millimeter scale variations of stable isotope abundance in carbonates from banded iron-formations in the Hamersley Group of Western Australia. Econ. Geol. 80:270–282Google Scholar
  3. Eichler, J. (1976) Origin of the Precambrian banded iron-formations. In: Wolf, K.H. (ed.) Handbook of Strata-bound and stratiform ore deposits, vol. 7. Elsevier, Amsterdam Oxford New York. pp. 157–201Google Scholar
  4. Floran, R.J., Papike, J.J. (1975) Petrology of the low-grade rocks of the Gunflint iron-formation, Ontario-Minnesota. Geol. Soc. Am. Bull. 86:1169–1190Google Scholar
  5. Gross, G.A. (1965) Geology of iron deposits in Canada. General geology and evaluation of iron deposits. Geol. Surv. Canada., Econ. Geol. 22:1–181 ppGoogle Scholar
  6. Gross, G.A. (1980) A classification of iron formations based on depositional environments. Can. Mineral. 18:215–222Google Scholar
  7. Henry, D.J., Guidotti, C.V. (1985) Tourmaline as a petrogenetic indicator mineral: an example from the staurolite-grade metapelites of N W Maine. Am. Mineral. 70:1–15Google Scholar
  8. Huber, N.K. (1959) Some aspects of the origin of the Ironwood iron minerals. Econ. Geol. 53:123–140Google Scholar
  9. Han, T.M. (1978) Microstructures of magnetite as guides to its origin in some Precambrian iron-formations. Fortschr. Miner. 56/1:105–142Google Scholar
  10. Han, T.M. (1982) Iron formations of Precambrian age: hematitemagnetite relationships in some Proterozoic iron deposits – A microscopic observation. In: Amstutz, G.C., El Goresy, A., Frenzel, G., Kluth, C., Moh, G., Wauschkuhn, A. Zimmermann, R.A. (eds.) Ore genesis. The state of art. Springer, Berlin Heidelberg New York, pp 452–459Google Scholar
  11. James, H.L. (1954) Sedimentary facies of iron-formation. Econ. Geol. 49:235–293Google Scholar
  12. James, H.L. (1955) Zone of regional matamorphism in the precambrian of Northern Michigan. Geol. Soc. Am. Bull. 66:1455–1488Google Scholar
  13. James, H.L. (1992) Precambrian iron-formations: nature, origin, and mineralogic evolution from sedimentation to metamorphism. In: Wolf, K.H., Chilingarian, G.V. (eds.) Diagenesis III. Developments in sedimentology, 47. Elsevier, Amsterdam Oxford New York, pp. 543–589Google Scholar
  14. Kennedy, W.Q. (1964) The structural differentiation of Africa in the Pan-African (500n m.y.) episode. 8th. Annual Report. Res. Inst. for African Geol., Leeds, pp. 48–49Google Scholar
  15. Klein, C., Jr. (1973) Changes in mineral assemblages with metamorphism of some banded Precambrain iron-formations. Econ. Geol. 68:1075–1088Google Scholar
  16. Klein, C., Beukes, N.J. (1993) Proterozoic iron-formations. In: Condie, K.C. (ed.) Proterozoic crustal evolution. Developments in Precambrian geology, vol. 10. Elsevier, Amsterdam Oxford New York, pp. 383–418Google Scholar
  17. Langmuir, D. (1971) Particle size effect on the reaction Goethite-Hematite + H2O. Am. J. Sci. 271:147–156Google Scholar
  18. McCurry, P. (1976) A general review of the geology of the Precambrain to Lower Paleozoic rocks of Nigeria. In: Kogbe, C.A. (ed.) Geology of Nigeria. Elizabethan, Lagos pp. 15–39Google Scholar
  19. Morris, R.C. (1985) Genesis of iron ore in banded iron-formation by supergene and supergene-metamorphic processes — a conceptual model. In: Wolf, K.H. (ed.) Handbook of strata-bound and stratiform ore deposits, vol. 13. Elsevier, Amsterdam Oxford New York pp. 73–235Google Scholar
  20. Morris, R.C. (1987) Iron ore derived by the enrichment in banded iron-formation. In: Hein, J.R. (ed.) The genesis of ores and petroleum associated with sedimentary siliceous deposits. Van Nostrand, New York pp. 231–267Google Scholar
  21. Mücke, A., Woakes, M. (1986) Pyrophanite: a typical mineral in the Pan-African Province of Western and Central Nigeria. J. African Earth Sci. 5/6:675–689Google Scholar
  22. Mücke, A. (1992) Entstehung und Entwicklung der gebänderten Eisenerze (BIF), dem häufigsten Lagerstättentyp — dargestellt am Beispiel Nigerias. Aufschluss 43/6:321–339Google Scholar
  23. Mücke, A., Annor, A. (1993) Examples and genetic significance of the formation of iron oxides in the Nigerian banded iron-formation. Mineral. Deposita 28:136–145Google Scholar
  24. Mücke, A. (1994) Part I. Postdiagenetic ferruginization of sedimentary rocks (sandstone, oolitic ironstone, kaolins and bauxites) — Including a comparative study of the reddening of red beds. Part II. Postdiagenetic ferruginization of Phanerozoic (oolitic) ironstone: a contribution to their origin. In: Wolf, K.H., Chilingarian, G.V. (eds.) Diagenesis IV. Developments in sedimentology, 51. Elsevier, Amsterdam Oxford New York, pp. 361–423Google Scholar
  25. Neumann, U. (1988) Mineralogie und Genese der Manganvorkommen in den Schiefergürtel von Nord-Nigeria. Unpublished Dr.-thesis, Universität Göttingen, Göttingen, 227 ppGoogle Scholar
  26. Rahaman, M.A. (1988) Advances in the study of the basement complex of Nigeria. In: Geol. Surv. of Nigeria (ed.) Precambrian geology of Nigeria. Esho, Kaduna, pp. 11–45Google Scholar
  27. Urban, H., Stribny, B., Lippolt, H.J. (1992) Iron and manganese deposits of the Urucum district, Mato Grosso do Sul. Brazil. Econ. Geol. 87:1375–1392Google Scholar
  28. Utke, A.W. (1989) Die spätproterozoische Kruste NW Nigeria: Geochemie und geotektonische Entwicklung. Berl. Geowiss. Abh. (A), 109:93 ppGoogle Scholar

Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • A. Mücke
    • 1
  • A. Annor
    • 2
  • U. Neumann
    • 3
  1. 1.Mineralogisch-Petrologisches Institut der Georg-August-UniversitätGöttingenGermany
  2. 2.Department of Geology and Mineral SciencesUniversity of IlorinIlorinNigeria
  3. 3.Institut für MineralogiePetrologie und Geochemie der UniversitätTübingenGermany

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