Geology and ore genesis of the Yu'erya gold deposit, eastern Hebei Province, China

• The Yu'erya gold deposit has a reserve of 65 t of contained gold averaging 2.3 g/t Au.
• There are two concealed plutons (G2 and G3) near the Yu'erya Granite (G1). G2 hosts a reserve of 8 t Au.
• The Mesozoic gold mineralization is related to the subduction of the Mongolia–Okhotsk and Paleo-Pacific oceans.

The large Yu'erya gold deposit (65 t of contained gold averaging 2.3 g/t Au) in the eastern part of the Hebei Province of China is spatially associated with the Yu'erya Granite, and a group of NE- and NNE-trending faults. The alteration associated with mineralization is characterized by the assemblage pyrite, quartz, sericite, albite, and carbonate. Four stages of mineralization, in chronological order, are (1) quartz and medium- to coarse-grained pyrite; (2) quartz, fine-grained pyrite, and gold; (3) quartz, polymetallic sulfide, tellurobismuthite, and gold; and (4) quartz, pyrite, and carbonate. Most of the gold was deposited during the second and third stages of alteration from mesothermal fluids. These fluids were relatively rich in H2O, CO2, K+, Ca2 +, Cl, and S, and low salinity. The H–O and sulfur isotope ratios determined for the mineralized samples indicate a magmatic source, and the Pb isotope data indicate that the Au mineralization originated from the mantle and lower crustal materials. Geochronological data indicate that the gold mineralization event was restricted to 200–163 Ma whereas the associated magmatism occurred between 200 and 150 Ma. This Mesozoic gold mineralization is related to the subduction of the Mongolia–Okhotsk and Paleo-Pacific oceans along the edges of the North China Craton.