岩浆氧逸度是制约Cu、Au成矿的重要因素之一,Cu、Au为亲硫元素,岩浆结晶分异过程中如果S2-大量存在就会导致Cu、Au硫化物过饱和而过早沉淀,不利于残余岩浆中Cu、Au的富集和晚阶段含Cu、Au岩浆流体的形成,因而不利于Cu、Au矿床的形成。高氧逸度条件下,岩浆中的硫绝大多数以SO42-和SO2形式溶解在硅酸盐熔体中,能形成硫化物的S2-含量很低,硫化物 Oxygen fugacity of magma is one of the important factors restricting the mineralization of Cu and Au. Cu and Au are the pro-sulfur elements. In the process of magma crystallization differentiation, if S2-mass exists, it will lead to supersaturation of Cu and Au sulphide and premature precipitation Is not conducive to the enrichment of Cu and Au in the remnant magma and the formation of Cu-containing and magmatic fluids in the late stage, which is not conducive to the formation of Cu and Au deposits. Under the conditions of high oxygen and fugacity, most of the sulfur in magma is dissolved in silicate melt in the form of SO42- and SO2, and the content of S2- which can form sulfide is very low.