Heavy metal contents in Fe-Mn nodules and crusts from R/V Vityaz polygons and stations in the East Indian Ocean

Regional variations in abundance, morphology, and chemical composition of Fe-Mn nodules have a zonal character. Due to circumcontinental zonality of terrigenous sedimentation the main mass of the nodules occurs in the pelagic part of the ocean, in areas of minimal sedimentation rates. In spatial variations in morphology and chemical composition of the nodules the latitudinal zonality is very clear and associated with latitudinal changes in facial conditions of sedimentation. Elevated contents of Mn, Ni, and Cu and of Mn/Fe ratio occur in nodules from the radiolarian belt. Changes of chemical composition of the nodules with depth (vertical zonality of mineralization) are confirmed. Local variations in abundance, morphology and chemical composition of the nodules are caused by ruggedness of relief and depth variations, variations in sedimentation rate, age of ore formation, intensity of diagenetic redistribution of metals.

(Table 1) Composition of bituminous substances in sediments from the East Pacific Rise

Bitumoid contents in metalliferous sediments from axial parts of the East Pacific Rise (EPR) have been studied. Maximal concentrations of bitumoid matter and aromatic hydrocarbons have been found in the axial zones of the EPR as a result of hydrothermal processes and accumulation of endogenous matter in the sediments. Distribution of bitumoids and hydrocarbons coincides with deposition of ore minerals that indicates similarity of their sources.