还原体（体系）与富铀矿的形成

铀是变价元素,还原体(体系)在铀富集过程中起着相当重要的作用。还原体(体系)可分两类:一类为自还原体(体系),这是指还原体(剂)是热液本身的还原体系,还原剂和铀在同一热液体系中搬运、迁移,然后在变化了的物理化学条件下,铀依靠热液本身的还原性能而被还原沉淀。另一类为外部还原体系,这是指铀的沉淀的还原作用是依靠围岩中的还原剂或地球化学场。两类还原体(体系)对铀的富集成矿具有不同方式,从而有不同的地质环境要求。

REDUCTION BODY(SYSTEM) AND THE FORMATION OF RICH-URANIUM ORE

Uranium is an element of variable valency.Reduction body (system) plays quite an important role in the process of uranium concentration, which can be divided into two patterns.One is auto-reduction body (system), Which means that reduction body (agent) is the reduction system of hydrothermal solution itself, reductant is transported and migrated with uranium in the same hydrothermal system and then uranium is reduced to precipitate in the changed physicochemical conditions, depending on the reducibility of hydrothermal solution itself.Another is exo-reduction system, which means that reducing action making uranium precipitation depends on the reductant or geochemical field of Wall rock.To these two kinds of reduction body (system), there are different ways for uranium concentration and mineralization, thus demanding different geological environments.