SHRIMP U-Pb dating of zircons from diorite batholith hosting Daping gold deposit in Ailaoshan gold belt, Yunan Province, China

Being one of the largest gold deposits in Ailaoshan gold belt, the Daping gold deposit is hosted in a ductile deformed and alterated diorite batholith, and is believed to be a typical Cenozoic orogenic type gold deposit. In this study, SHRIMP U-Pb dating of zircon from the diorite batholith was performed, and the result is 773 +/- 12 Ma, suggesting that the diorite was a Late Proterozoic batholith, but not a commonly recognized Caledonian rock body. The diorite batholith is a product of large-scale basic to acidic magmatism during the Jinning-Chengjiang epoch, and is corresponding to a period of Gondwana accretion after Rodinian dispersion. The forming age of the diorite is nearly the same as the high temperature 40Ar-39Ar plateau age (765. 5 +/- 7. 0Ma) of fluid inclusions in Daping auriferous quartz veins, suggesting that the Daping gold deposit was formed during multiple metallogenic epochs; the major ore body was formed during Cenozoic orogeny, while the gold mineralization was started during Jinning orogeny. Cenozoic epoch zircons are also recognized in the diorite, and the age 33.7 +/- 1. 1Ma is nearly the same as the 40Ar-39Ar age (33. 76Ma) of hydrothermal sericite from the Daping auriferous quartz veins, suggesting that the some of the zircons were probably formed during extensively ductile deformation and subsequent magmatic partial melting.