氧化还原作用对铀成矿的意义——以相山西部流纹英安岩铀矿为例

铀是敏感的变价元素,在氧化状态下U6+能随岩浆热液迁移;而在还原状态下U4+形成沥青铀矿、钛铀石等发生沉淀。本文通过对相山西部流纹英安岩原岩和含铀矿石的鉴定和化学分析,大致说明流纹英安岩中的铀矿石主要是赋存在岩石微裂隙中的沥青铀矿。同时推断深部岩浆上没有喷涌过程中,U4+在深部弱还原环境下被氧化成UO22+而随热液迁移;热液进一步上涌逐渐转为弱氧化环境。UO22+又在弱氧化环境下被还原成U4+而富集沉淀形成铀矿体,U4+和UO22+的相互转化不仅仅和热液氧化还原状态相关,还和热液的成分及温度、压力、pH值等物理条件相关。

Meaning of redox action to uranium mineralize: A case study on uranium occurred rhyodacite of west Xiangshan area

Uranium is a sensitive variable elements.On the oxidize station,uranium is U6+ move with magmatic hydrothermal;on the deoxidize station,uranium turn into U4+ constitude uraninite and titanurus which will settled;The article through the result of rock ore appraisal and chemical analysis of rhyodacite from west of Xiangshan area,which indicate most of pitchblende were occurred in microfracture of rhyodacite. When deep magma rise,UO22+ will be oxidized from U4+ in weak reductive environment and will move with hydrotherm. With the further erupt,hydrotherm is gradually change into weak oxidative environment. U4+ will concentrate and precipitate which reduced from UO22+ in weak reductive environment. The change between U4+ and UO22+ is relating to temperature、pressure、p H and so on,not only with redox state.