GEOLOGY AND GENESIS OF THE YAO'AN GOLD DEPOSIT RELATED TO ALKALI-RICH MAGMATIC ROCK IN YUNNAN PROVINCE

Yao'an gold deposit,located in Northwest Yunnan Province,is a typical deposit related to the Himalayan epoch alkali-rich intrusive rocks.The ore-forming process could be divided into three epoches and five stages.There are several obvious alteration zones in the ore district.The occurrence of ore-bodies or ore-veins are closely related to the alkali-rich rock bodies/veins spatially,temporally and genetically.By researches on the gold content,isotopes and REE in different types of rocks,it is concluded that the origin of the gold and fluid was not from the alkali-rich rocks,but mainly from the depth of the earth(mantle or the mixing zone of mantle and lower crust)The relationship between magmatic evolution and gold mineralization is further discussed.