Iron formations

Barret, J.J., Faraick, W. and Jarvis, I. (1988) Rare-earth element geochemistry of some Archean iron formations north of Lake Superior, Ontario. Can. J. Earth Sci., 25, 570-586. 

Basalt, granite, manganese nodules, shale, flint clay, iron formation materials, phosphate rock, fertilizers Calcareous loam soil, loess, polluted farmland soil, sand soil... 

By far the most important ores of iron come from Precambrian banded iron formations (BIF), which are essentially chemical sediments of alternating siliceous and iron-rich bands. The most notable occurrences are those at Hamersley in Australia, Lake Superior in USA and Canada, Transvaal in South Africa, and Bihar and Karnataka in India. The important manganese deposits of the world are associated with sedimentary deposits the manganese nodules on the ocean floor are also chemically precipitated from solutions. Phosphorites, the main source of phosphates, are special types of sedimentary deposits formed under marine conditions. Bedded iron sulfide deposits are formed by sulfate reducing bacteria in sedimentary environments. Similarly uranium-vanadium in sandstone-type uranium deposits and stratiform lead and zinc concentrations associated with carbonate rocks owe their origin to syngenetic chemical precipitation. 

The Dumas Formation is uncomformably overlying the Archean Superior Province. It hosts metasediments and intercalated iron formations, as well as peridotite and gabbro bodies, which were identified and separated with the help of both Band ratio and Principal Component Analysis. 

Nealson, K. H., and C. R. Myers (1990), "Iron Reduction by Bacteria A Potential Role in the Genesis of Brandes Iron Formation", Amer. J. of Science 290, 35-45. 

Becker RH, Clayton RN (1976) Oxygen isotope study of a Precambrian banded iron-formation. Hamersley Range, Western Australia. Geochim Cosmochim Acta 40 1153-1165 Beard BL, Johnson CM (2004) Fe isotope variations in the modem and ancient earth and other planetary bodies. Rev Mineral Geochem 55 319-357... 

Figure 2. Co-variation of Fe/ "Fe and Fe/ "Fe ratios of individual layers from Banded Iron Formations, modified from Johnson et al. (2003a). The horizontal axis shows isotopic compositions in 5 Fe (bottom) and Fe (top), and the vertical axis shows values in d Fe (left) and s Fe (right). Point A has a d Fe of +1.00%o, which corresponds to an s Fe value of +15.0. Figure illustrates the multiple ways in which the same Fe isotope composition may be reported when isotopic variations are due to mass-dependent processes. See text for discussion.

Figure 21. Plot of the measured 6 Fe value of pairs of magnetite and siderite layers from Banded Iron Formations. Data from Johnson et al. (2003a) and C. Johnson and B. Beard unpublished.

Beukes NJ, Klein C (1992) Models for Iron-formation deposition. In The Proterozoic Biosphere A multidisciplinary study. Schopf JW, Klein C (eds) Cambridge University Press, New York, p 147-151 Birck JL (2004) An overview of isotopic anomalies in extraterreshial materials and their nucleos>mdietic heritage. Rev Mineral Geochem 55 25-64... 

Ewers WE (1983) Chemical factors in the deposition and diagenesis of banded iron-formation. In Iron Formations Facts and Problems. Trendall AF, Morris RC (eds) Elsevier, Amsterdam, p 491-512 Fantle MS, DePaolo DJ (2002) The isotopic composition of continental iron and implications for the global Fe cycle. EOS Trans Am Geophys Union 83 V22B-1234... 

Klein C, Beukes NJ (1989) Geochemistry and sedimentology of a facies transition from limestone to iron-formation deposition in the early Proterozoic Transvaal Supergroup, South Africa Econ Geol 84 1733-... 

Figure 19. Iron isotope fractionations between magnetite and Fe carbonates from adjacent bands in Banded Iron Formations (Johnson et al. 2004a), compared to Fe(II)aq sources and Fe pathways inferred from the Fe isotope fractionations given in Table 3. values are as measured, and the scales for...

Bau M, Dulski P (1996) Distribution of yttrium and rare-earth elements in the Penge and Kuruman iron-formations, Transvaal Supergroup, South Africa. Precam Res 79 37-55 Bau M, Hohndorf A, Dulski P, Beukes NJ (1997) Sources of rare-earth elements and iron in Paleoproterozoic iron-formations from the Transvaal Supergroup, South Africa evidence from neodymium isotopes. J Geol 105 121-129... 

Baur ME, Hayes JM, Studley SA, Walter MR (1985) Millimeter-scale variations of stable isotope abundances in carbonates from banded iron-formations in the Hamersley Group of Western Australia. Econ Geol 80 270-282... 

Butler P (1969) Mineral compositions and equilibria in the metamorphosed iron-formation of the Gagnon region, Quebec, Canada. J Petrol 10 56-101... 

Harder EC (1919) Iron-depositing bacteria and their geologic relations. US Geol Surv Prof Pap 113 Hartman H (1984) The evolution of photosynthesis and microbial mats a speculation on banded iron formations. In Microbial Mats Stromatolites. Cohen Y, Castenholz RW, Halvorson HO (eds) Alan Liss Pub, New York, p 451-453... 

Johnson CM, Skulan JL, Beard BL, Sun H, Nealson KH, Braterman PS (2002) Isotopic fractionation between Pe(III) and Ee(II) in aqueous solutions. Earth Planet Sci Lett 195 141-153 Johnson CM, Beard BL, Beukes NJ, Klein C, O Leary JM (2003) Ancient geochemical cycling in the Earth as inferred from Ee isotope studies of banded iron formations from the Transvaal Craton. Contrib Mineral Petrol 144 523-547... 

Kaufman AJ (1996) Geochemical and mineralogic effects of contact metamorphism on banded iron-formation an example from the Transvaal Basin, South Africa. Precam Res 79 171-194... 

Klein C (1974) Greenalite, stilpnomelane, minnesotaite, crocidolite, and carbonates in a very low-grade metamorphic Precambrian iron-formation. Can Min 12 475-498 Klein C (1978) Regional metamorphism of Proterozoic iron-formation, Labrador Trough, Canada. Am Min 63 898-912... 

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