Cobalt-Rich Ferromanganese Crusts of the Kotzebue Guyot of the Magellan Seamounts of the Pacific Ocean: Conditions of Occurrence, Mineralogy, and Geochemistry

This article describes the geological conditions for the formation of cobalt-rich ferromanganese crusts (CFCs) on the Kotzebue Guyot in the system of the Magellan Seamounts of the Pacific Ocean. It is established that the crusts are deposited on dense organogenic-clastic limestones, breccias, and volcanoclastic rocks. The crusts are three- or four-layer formations. The main ore minerals of all crust layers are Fe-vernadite, vernadite, and Mn-feroxyhyte. It is established that the content of Fe increases and that of Mn decreases from layer I-1 to layer III. For ore metal cations-Co2+, Ni2+, and Cu2+-no regularity in their distribution is established: in some crusts, their content decreases from layer I-1 to layer III, and in others, in contrast, it increases. The most stable contents in guyot crusts are observed for heavy metal cations: Zn2+, Mo6+, Sr2+, Cd2+, Ba2+, and Pb2+. The contents of rare-earth metal cations in layers of different crusts and in crusts as a whole are quite stable and close to each other, and their distribution does not coincide with the distribution of Fe(III). The distribution of Ce3+ cations is similar to the distribution of another ore-forming element of crusts, Mn(IV).