Which tectonic setting is associated with porphyry copper and skarn deposits?

Which tectonic setting is associated with porphyry copper and skarn deposits?

• A. Evaporite deposits
• B. Placer gold
• C. Volcanogenic massive sulfide
• D. Porphyry and skarn deposits with lead, zinc, and silver

Answer: (D)

Porphyry copper and skarn deposits form in subduction-zone environments, specifically at continental magmatic arcs above a subducting slab. In these settings, intruding magma feeds extensive hydrothermal systems that concentrate copper to create large porphyry copper bodies. When the hot fluids interact with carbonate rocks in the surrounding country rocks, they can cause contact metamorphism and mineralize as skarns, which often host lead, zinc, and silver in addition to copper. This combination—porphyry copper developed in a magmatic arc and skarn formed at the contact with carbonate rocks near a subduction zone—defines the tectonic setting described. Evaporite deposits form from evaporation in arid basins, placer gold from alluvial processes, and volcanogenic massive sulfide deposits from submarine volcanic centers at divergent or back-arc settings, so they don’t match the subduction-arc context of porphyry and skarn systems.

Porphyry copper and skarn deposits form in subduction-zone environments, specifically at continental magmatic arcs above a subducting slab. In these settings, intruding magma feeds extensive hydrothermal systems that concentrate copper to create large porphyry copper bodies. When the hot fluids interact with carbonate rocks in the surrounding country rocks, they can cause contact metamorphism and mineralize as skarns, which often host lead, zinc, and silver in addition to copper. This combination—porphyry copper developed in a magmatic arc and skarn formed at the contact with carbonate rocks near a subduction zone—defines the tectonic setting described. Evaporite deposits form from evaporation in arid basins, placer gold from alluvial processes, and volcanogenic massive sulfide deposits from submarine volcanic centers at divergent or back-arc settings, so they don’t match the subduction-arc context of porphyry and skarn systems.