The Dongchuang gold deposit, which is a typical orogenic gold deposit in the Xiaoqinling District, is one of the super-large gold deposits of China. The ore-forming age of the Dongchuang gold deposit is still in dispute. The geology of the deposit indicates that the ore-forming process can be classified into four stages: the formation of coarse grain pyrite and quartz (stage Ⅰ) , the formation of fine grain pyrite and quartz (stage Ⅱ) , the formation of polymetallic sulfide (stage Ⅲ ) , and the formation of carbonate and quartz (stage Ⅳ ). The Ar-Ar ages of stages Ⅰ,Ⅱ,and Ⅲ were determined in two different laboratories. The age results implied that the Ar-Ar plateau age of quartz in stage Ⅰ is 142. 9～2. 9Ma; the Ar-Ar plateau age of sericite in stage Ⅱ is 132. 2 ～2. 6Ma, and its isochron age is 132. 6～2.7Ma; and the Ar-Ar plateau age of quartz in stage Ⅲ is 128. 3～ 6. 2Ma. These age results, which are in accordance with the geology, indicated that the Dongchuang gold deposit was formed during 143 to 128Ma, which was also the transition period of compression to extension in the Jurassic to Cretaceous period. The environment with low pressure and high temperature of the transition period could be the most suitable ore-forming geochemical kinetic background for orogenic deposit.
Dongchuang gold deposit
Ar-Ar plateau age
orogenic gold deposit
transition period of compression to extension