Variations in the elemental composition of ferromanganese structures from Lake Baikal

The elemental composition of ferromanganese sedimentary structures from the bottom of Lake Baikal represented by nodules and crusts, as well as the enclosing sediments, have been studied by the atomic absorption, chemical, and ICP-MS methods. It is established that the contents of the rock-forming and accompanying elements in them are highly variable. In this connection, the examined samples are divided in two groups differing by their Mn/Fe values. In most of the samples, they range from 0.01 to 0.1, although some of the ferromanganese structures or their parts are substantially enriched in manganese. The contents of most of the rare and dispersed elements in the ferromanganese structures are usually at the background level, although the samples maximally enriched in iron or manganese are characterized by relatively high copper, nickel, cobalt, vanadium, zinc, and molybdenum concentrations.