Relationship between the geochemical characteristic of the rock and uranium metallogenetic in middle Cuojiaoma rock mass of western Sichuan region

Cuojiaoma rock mass located in the mid-north of Yidun island arc belt, form in indosinian epoch to Yanshan epoch. It contains monzonitic granite, granodiorite and syenogranite. The geochemical characteristic of the rock indicates that: the rock mass is belong to high potassium calc-alkaline series, because of rich Si (the average content of W (Si0₂) is 72.5%), rich alkaline (the average content of W (Na₂0+K₂0) is 7.41%), supersaturated aluminum (the average content of W (A1₂0₃) is 12.97%) and strong crystallization differentiation ((DI) average is 86.46); the rock mass shows the right type because total amount of rare earth is low, light rare earth is rich and δEu (average is 2.11) is strong loss; the geochemical characteristic of the rock similar with uranium granite in south China shows that the Cuojiaoma rock mass is the advantageous rock mass for uranium mineralization. The mineralized monzonitic granite is more rich Si (the average content of W (Si0₂) is 75.1%), more rich alkaline (the average content of W (Na₂0+K₂0) is 7.9%), lower total amount of rare earth and strong losses of δ Eu (average is 0.23). These characteristics of mineralized monzonitic granite show that uranium mineralization closely relates to magmatic differentiation ((DI) average is 90.3), the degree of acid and lower total amount of rare earth. (authors)