Critical metals in manganese nodules from the Cook Islands EEZ, abundances and distributions

摘要: Abstract The Cook Islands (CIs) Exclusive Economic Zone (EEZ) encompasses 1,977,000 km2 and includes the Penrhyn Samoa basins abyssal plains where manganese nodules flourish due to availability of prolific nucleus material, slow sedimentation rates, strong bottom currents. A group CIs was analyzed for mineralogical chemical composition, which include many critical metals not before nodules. These have varying sizes nuclei material; however all are composed predominantly δ-MnO2 X-ray amorphous iron oxyhydroxide. mineralogy, Fe/Mn ratios, rare earth element contents, growth rates (mean 1.9 mm/106 years) reflect formation primarily by hydrogenetic precipitation. paucity diagenetic input can be explained low primary productivity at surface resultant organic matter content in seafloor sediment, producing oxic sub-seafloor environments. contain high mean contents Co (0.41%), Ni (0.38%), Ti (1.20%), total elements plus yttrium (REY; 0.167%), also Mo, Nb, V, W, Zr. Compiled data from a series four cruises Japan International Cooperation Agency Mining agency 1985 2000 were used generate map that defines statistical distribution nodule abundance throughout EEZ, except Manihiki Plateau. shows belt (19–45 kg/m2) starts southeast corner runs northwest, bifurcates into SW trending branch. Small, isolated areas abundances up 58 kg/m2. Six ~ 20,000 km2 particularly chosen represent potential exploration areas, maps metal concentration generated visualize extrapolate estimated tonnages within six sites EEZ as whole. Grades Mn, Cu, abundance; however, Ti, Co, REY show high. Of identified range one northern end N-S main optimizes most would yield highest dry metric tons Mn (61,002,292), (1,247,834), Mo (186,166), V (356,247), W (30,215), Zr (195,323). When compared with Clarion–Clipperton Zone, higher (> 25 kg/m2 over ~ 123,844 km2), more enriched green-tech, high-tech, energy Te, REY, Pt, significant resource these their prices, demand, abundance, will allow smaller footprint 20-year mine site therefore environmental impact.