ABSTRACT

Sediment cores of various types were cut into sections each 2 to 10cm in length and analyzed for Cu, Zn, Ni, Co, Pb and Ba after chemical separation into acid soluble, reducible and refractory fractions. The results are compared with the data obtained for Mn. They proved the migration of Mn in pelagic sediment to have resulted from changes in redox conditions. Surface oxidizing sediment usually contains more of these transition metals than sediment from greater depths. Thus an excess portion of metals in the surface will be lost during early diagenesis. In some of the weakly oxidizing deep sediment transition metals as well as Mn are concentrated and the composition of the excess amounts is similar to that of the manganese nodules unless major components, such as silica and carbonate, are included. The deep layer enriched in transition metals is inferred to be diagenetically formed. In some sections of the deep reducing sediment, Mn is also concentrated in the acid soluble fraction, and may be precipitated as carbonate, but this layer does not contain large amounts of any other transition metals.