The Ailao Mountain is one of the most important metallogenic belts of polymetallic deposits in the Sanjiang region,southwestern China.Located in the southern segment of this metallogenic belt,the newly-discovered Chang’an gold deposit is large in scale(Fig.1A),and has attracted much attention among geologists.The ore-hosted The Ailao Mountain is one of the most important metallogenic belts of polymetallic deposits in the Sanjiang region, southwestern China. Located in the southern segment of this metallogenic belt, the newly-discovered Chang’an gold deposit is large in scale (Fig. 1A) , and has attracted much attention among geologists.The ore-hosted