Mineral Deposit Model of Cu–Fe–Au Skarn System in the Edongnan Region, Eastern China

Abstract Cu and Fe skarns are the world's most abundant and largest skarn type deposits, especially in China, and Au‐rich skarn deposits have received much attention in the past two decades and yet there are few papers focused on schematic mineral deposit models of Cu–Fe–Au skarn systems. Three types of Au‐rich deposits are recognized in the Edongnan region, Middle–Lower Yangtze River metallogenic belt: ∼140 Ma Cu–Au and Au–Cu skarn deposits and distal Au–Tl deposits. 137–148 Ma Cu–Fe and 130–133 Ma Fe skarn deposits are recognized in the Edongnan region. The Cu–Fe skarn deposits have a greater contribution of mantle components than the Fe skarn deposits, and the hydrothermal fluids responsible for formation of the Fe skarn deposits involved a greater contribution from evaporitic sedimentary rocks compared to Cu–Fe skarn deposits. The carbonate‐hosted Au–Tl deposits in the Edongnan region are interpreted as distal products of Cu–Au skarn mineralization. A new schematic mineral deposit model of the Cu–Fe–Au skarn system is proposed to illustrate the relationship between the Cu–Fe–Au skarn mineralization, the evaporitic sedimentary rocks, and distal Au–Tl deposits. This model has important implications for the exploration for carbonate–hosted Au–Tl deposits in the more distal parts of Cu–Au skarn systems, and Fe skarn deposits with the occurrence of gypsum‐bearing host sedimentary rocks in the MLYRB, and possibly elsewhere.