Factors Controlling the Grade and Abundance of Ferromanganese Crusts: The Northwestern Pacific Ocean as Case Study

摘要

The abundance of the ferromanganese crusts is basically controlled by the total time lapsed for growth of the crusts and sediment accumulation. Small-scale variation in microtopography and occurrence of hydrogenetic crusts were found in some seamounts with sea-bed photography and submersible observations. The genetic control on ore grade or geochemisty has been also characterized for hydrogenetic, hydrothermal, and much less often diagenetic manganese deposits. The fine-scale temporal variation within samples is also common, which should be noted in evaluating the crusts as ores.