Volcanogenic deposits formed near the hydrothermal source would be

• A. Sandstone-hosted uranium deposits
• B. Massive sulfide deposits containing Cu, Ni, Zn, Ag
• C. Lateritic nickel deposits
• D. Placer gold deposits

Answer: (B)

Volcanogenic massive sulfide deposits form when metal-rich, high-temperature hydrothermal fluids vent from volcanic activity on the seafloor and precipitate sulfide minerals as they mix with cooler seawater near the source. This creates thick ore bodies rich in copper, zinc, and often silver, and sometimes nickel, right at or near the hydrothermal vents. The other deposit types arise from different settings and processes: sandstone-hosted uranium forms from diagenetic and redox conditions in porous sandstones; lateritic nickel comes from intense tropical weathering of nickel-bearing rocks; placer gold concentrates from mechanical movement of auriferous material in streams. Thus, near the hydrothermal source, volcanogenic deposits are characteristically massive sulfide bodies containing Cu, Zn, Ag, and often Ni.