SUMMARY

Research on anomalous features of radioactive gas to detect buried ores in placer zones of coastal areas of Central Việt Nam

                Lê Khánh Phồn, Nguyễn Anh Tuấn, Nguyễn Văn Nam, Nguyễn Thái Sơn

Theoretical calculation of the concentration of radon and thoron on the model of the typical body of coastal placer deposits in Central Việt Nam have been showing that bedded ore bodies contain horizontal beds of radioactive substance with the dimensions corresponding to half-space of infinite radiation giving the basis to apply the method of radioactive gas and to interpret factual materials. Results of the radioactive survey on five coastal placer deposits in Central Việt Nam have been proving the ability of detecting buried ores by characteristics of anomaly of radioactive gas. On the ore body exposed on the surface, the concentration of anomaly of thoron depends on ore content, but always larger than 3 to 5 times of anomaly of radon. When the ores are covered, the concentration of thoron will strongly decrease; when the thickness of covering soil h >80 cm, the anomaly of thoron concentration will be smaller than radon one, but when the thickness of covering soil 3 m <h< 10 m, the radon concentration will completety disappear and still remains the ability of detecting weak radon concentration.

Ngày nhận bài: 6/7/2009

Người biên tập: TS. Nguyễn Tuấn Phong (Cục Địa chất và Khoáng sản Việt Nam)