Abstract:

On the basis of characteristics of the basalt and basaltic volcanic breccia from western Pacific Ocean seamount and the composition changes of the vesicle filling,this paper will discuss relation between the overlying cobalt crust and the seamounts basalt.The bedrocks for cobalt-rich crusts are the alkaline basalt and basaltic volcanic breccia. The alkaline basaltic vesicle filling with S-type and C-type. S-type and C-type vesicle fillings do not exist in one vesicle. S-type vesicle filling composition rich in Si, Fe, K, Mg, Al and Co content generally changes between 0.17% and 0.46%. S-type vesicle filling composition is similar to the composition of alkali basalt. S-type vesicle filling source may be the alkali basalt. C-type vesicle filling composition is rich in O, Ca, C and with a small amount of Si, Al, Mg, Fe, K and other elements, which may be related to ocean water material deposition. The deposition process of the S-type vesicle filling reflected Si, Al, Fe, Mg, K and other elements is similar to the early trends of the deposition process of cobalt-rich crusts. The source of early deposition of cobalt-rich crusts may have relation to the alkali basalt. The source of early deposition of cobalt-rich crusts may be a result of the joint deposition of alkaline basalts and ocean water.

Key words: western Pacific Ocean seamount, basalt, cobalt-rich crusts, vesicle filling, source