钙结岩型铀矿勘查中活性炭吸附测氡方法应用——以纳米比亚欢乐谷南部地区为例

Application of Activated Charcoal in Measuring Radon for the Exploration of Calcrete-type Uranium Deposits——A Case Study in the South of Happy Valley Area in Namibia

在纳米比亚欢乐谷南部地区开展的活性炭吸附测氡方法应用试验结果显示,氡异常能够较好地反映隐伏钙结岩型铀矿化信息,而且铀矿体上方土壤中的氡浓度随深度增大的变化率要明显大于无矿地段,前者为后者的5~16倍。在测区的西南部圈定了一处面积约为5km2的氡异常,经地质探槽揭露,伽马能谱当量U含量高达500×10-6,并在探槽内发现了次生铀矿物,推断此处氡异常是由钙结岩型铀矿化引起的,为进一步的地质找矿工作提供了有价值的线索。

Activated charcoal was used to measure the radon concentration in the south of Gaudeanmus area, Namibia Pilot and application of radon measurement using activated carbon were carried out in southern Happy Valley area, Namibia. The test result showed that U ore bodies were manifested as a high and sharp radon anomaly. The variation of radon concentration with depth over the known uranium mineralization is much higher than that over the barren area, and the change rate of the former is about 5 to 16 times of the latter. A new anomaly area of 5 km2 was delineated in the southwest of working area with known clacrete-type uranium mineralization. After geological trench checking, the anomaly was found with 500 × 10-6 eq U by gamma ray spectrum and secondary uranium mineral was discovered which indicated that this anomaly is probably caused by the concealed ealcrete uranium mineralization.