Ferromanganese nodules formation

Variability of U and some trace elements in ferromanganese nodules of the Clarion-Clipperton zone (Pacific Ocean) and mechanism of their formation... 

Guliy, V. 2004. Peculiarities of morphology and composition of ferromanganese nodules and possible mechanism of their formation. Geologist of Ukraine, 3, 61-71. 

CFA is omnipresent in pelagic sediments, ferromanganese nodules, and seamount crusts, and marine phosphorites on continental margins and seamounts. Supply of phosphate by oxidation of organic matter and pre-concentration of phosphate by iron oxyhy dr oxides, supply of calcium by dissolution of carbonates or carbonates acting as substrates, and supply of fluorine from seawater are all important factors in the formation of marine phosphorites. 

Inorganic mechanisms for the formation of ferromanganese nodules and crusts imply that it should be theoretically possible to form nodules in marine and freshwater environments without the aid of organisms. However, organic interactions could accelerate nodule formation in a number of direct... 

In addition to the above direct contributions of microoi anisms to the formation of ferromanganese nodules, several indirect contributions may also be possible, and may indeed be essential to the formation of extensive ferromanganese deposits, especially those highly enriched in trace metals other th2in iron and manganese. For example, the most extensive deposit of... 

In this chapter, we have attempted to relate current ideas on the roles of microorganisms to the genesis of two very different types of iron deposits — one very ancient (Precambrian BIF s) and one modem (ferromanganese nodules and crusts) one comprising the most extensive resource of iron ore on land, and the other comprising the most extensive mineral deposit in the oceans. We can conclude that organisms were almost certainly involved, directly or indirectly, in the formation of both types of deposits, but exactly how and to what extent they are involved remain unanswered questions even for modem deposits. 

Ehrlich (1975) has recently reviewed aspects of microbial participation in the formation of ferromanganese concretions in the deep sea. Other aspects of the biogeochemistry of ferromanganese nodules are given by Lundgren and Dean in Chapter 4. 

Nickel and zinc in soil ferromanganese nodules. One of the most efficient and durable process responsible for trace metal sequestration in soils is the formation of ferromanganese micronodules, which often have been compared to the well-known oceanic Mn nodules (Glasby et al. 1979 White and Dixon 1996 Han et al. 2001) (Fig. 30a). Although soil micronodules are the premier reservoir for many trace elements in soils, the crystal chemistry of the sequestered elements remains unknown. Chemical analyses of individual nodules from Sicilia and New Zealand showed that some elements, such as Co, Ce, Ba, Pb, Ni, are several times to more than one order of magnitude enriched in the concretions relative to the soil matrix, whereas others are less (e g., Zn) or even depleted (Childs 1975 Palumbo et al. 2001) (Fig. 30b). Since nodules are formed in situ within the soil matrix by local enrichment of Fe and Mn oxides, the observed difference of metal enrichment in the concretions relative to the soil matrix likely results from a difference of metal affinity for soil minerals. The micronodule analyzed here by... 

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