Thick Ore Crusts of the Sea of Okhotsk Super-Enriched in Nickel

Ore crusts up to 20 cm thick dredged from a depth of 1500–1300 m in the eastern part of the Akademii Nauk Rise in the Sea of Okhotsk were studied. The main ore mineral is vernadite. The crusts contain an average of 32% manganese and 11% iron, are extremely enriched in nickel, and according to the combination of features, are hydrogenetic. The nickel content in samples, according to inductively coupled plasma mass spectrometry, reaches 1.3% with an average value of 1.0%, and point microprobe analyses yield 2.6% with an average value of 0.9%. Based on a summary of our own and published data, a central-southern nickel-promising region was outlined in the Sea of Okhotsk. The nickel content in hydrogenetic ferromanganese crusts and nodules of the region is comparable to that in cobalt-rich manganese crusts and polymetallic ferromanganese nodules of the World Ocean.