Abstract:

According to the different genesis, marine ferromanganese deposits can be classified into hydrogenetic ferromanganese deposits, diagenetic ferromanganese deposits and hydrothermal ferromanganese deposits. REEs in hydrogenetic and diagenetic ferromanganese deposits from Pacific and Indian Ocean were analyzed by ICP-MS, and were compared with REEs in the representative hydrothermal ferromanganese deposits, to understand the characteristics of REEs and the internal relationship between REEs and growth environment of hydrogenetic ferromanganese deposits, diagenetic ferromanganese deposits and hydrothermal ferromanganese deposits. There are significantly differences in rare earth elements characteristics among the three types. These indicate that hydrogenetic ferromanganese deposits grow in relative stability and similar oxidizing environment; diagenetic ferromanganese deposits form in sub-oxidizing to reducing environment, but at some periods, parts of them may be affected by hydrogenesis; whereas hydrothermal ferromanganese deposits come from hydrothermal fluid and seawater, and there are great differences of growth environment among hydrothermal ferromanganese deposits in different areas.

Key words: marine, ferromanganese deposits, rare earth elements, geochemistry