含钍沥青铀矿的发现及其意义

The Discovery and Significance of Thorium-bearing Pitchblendet

一、地质背景 含钍沥青铀矿产区位于华南加里东冒地槽褶皱带北东段,赣杭中生代酸性火山岩带的破火山口中。火山岩带由上侏罗统的酸性火山岩系构成,岩性主要为砂岩、砂砾岩、粉砂岩、流纹质凝灰岩、熔结凝灰岩、流纹英安岩和巨厚层碎斑流纹岩等,还有火山活动晚期呈环状次火山岩体群形式产出的花岗斑岩和英安斑岩等。

Thorium-bearing pitchblende (U0.684+U0.276+Th0.054+)O_(2.27) is a variety of pitchblende discovered in China, and it is an important primary economic uranium mineral. The main difference between thorium-bearing pitchblende and pitchblende is the high ThO_(2) content (1.79-10.03%) and high Th:U ratio (0.02-0.14), and it is similar to pitchblende in other chemical and physical properties. At medium-low temperatures, when ore solution has soufficient Fconcentration which forms fluoride and complex compound with uranium and thorium, uranium and thorium can migrate together in the same solution. In the process of ore formation, uranium and thorium can not separate completely but precipitate together, because ore solution is rapitedly cooled. The discovery of thorium-bearing pitchblende indicates that the isomorphism replacement of uranium and thorium not only takes place at high temperatures but also does under the conditions of medium-low temperatures.