COMPARISON OF CHARACTERISTICS OF POLYMETALLIC NODULES FROM THE CENTRAL PACIFIC BASIN AND EAST PACIFIC BASIN
Liang Dehua Xu Kangli(Guangzhou Marine Geological Survey,MGMR,Guangzhou,510075,China)
The study area means the Central Pacific Basin(CP area)and the East Pacific Basin(CC area).Polymetallic nodules of the CP area are distinct in feature from those of CC area. The former are mainly spherical and ellipsoidal ,while the latter are cauliflower-like.Thestudy shows that abundance of the nodules from CP area is comparatively higher with anaverage of about 10kg/m￣2,and the grade is lower with an average of around 1.4%. Man-ganese minerals are mainly composed of δ-MnO_2(vernadite) and nodules are mainly hy-drogenic. On the contrary,nodules from CC area have lower abundance(4-6kg/m￣2)andhigher grade(2.6% on the average).The manganese minerals are dominated by todor-okite and vernadite,and the nodules are mainly eogenetic or in mixed origin. According to grades of the nodules, we suggest that the economic value of the nod- ules from CC area is higher than that of the nodules from CP area.The distinct characteristics of nodules from the two areas are due to factors such asmatter source and formation environment including geographic environment,structuralposition,topographic feature,sediment type and geochemical interface etc.