Ocean-floor Manganese Crust

Synonym

Co-rich Manganese Deposit, Co-rich Manganese Crust

Required Geological Setting

Ocean floor

Occurrence

Crust, pebbles, and nodules deposit on 500 - 2,500 m depth of water slops and summits of seamounts in the low-latitude Pacific Ocean. Crusts were formed on rocks of seamounts such as volcanic rocks, limestone, phosphate rocks. Thickness of crusts is a few cm to 10 cm. It is composed of Mn and Fe with minor Co, Ni, and Cu. Co concentration is up to 1%. It is considered that metallic elements released in seawater by underwater hydrothermal activities deposit directly from seawater in oxygen minimum zones of the Pacific Ocean. As crusts deposit very slowly, they are not observed in such circumstances as continental shelves where large amounts of sediments are supplied.

Mineral Assemblages

Vernadite