Classification of seamount morphology and its evaluating significance of ferromanganese crust in the central Pacific Ocean

Using the SeaBeam technology, the morphology of seamount and its relation to the formation of cobalt-rich crust in the central Pacific Ocean were surveyed during the cruise in 2003 for marine mineral resources.The result shows that seamounts can be divided morphologically into the spire seamount and the flat topped seamount.These two types of seamount bear great differences in their landform, lithology and cobalt-rich crust.On the upper portion of the flat topped seamount, the flat top and the sharp escarpments are unfavorable to the growth of crust, and, consequently, the crusts here are mostly laminar or gravelly, their thicknesses generally show great variations, and the consecutive ore body often develops in its deep water region.On the spire topped seamount, however, the flat area is small, and its gradient is constant without large variation from the top to the bottom.This favors the growth of cobalt-rich crust and often leads to consecutive tabular ore body of medium thickness, occurring on the spire topped seamount from the shallow water region to the deep water region.The cobalt-rich crust on the spire topped seamount is much better than that on the flat topped seamount for the crust abundance, crust coverage and number of ore-occurrences within unit area.Furthermore, the crust on the spire topped seamount is rich in cobalt, nickel, manganese elements of high economic value.Because the crust with high quality ore often occurs in the shallow water region on the spire topped seamount, it can be mined and use more easily in the future.