【作者】 王霆；

【导师】 王南萍；

【作者基本信息】 中国地质大学（北京） ， 地球探测与信息技术， 2011， 硕士

【摘要】 随着我国的核电建设进入高速发展阶段,对核燃料铀的需求也出现了井喷式的增长。我国目前铀矿探明储量有限,为了解决核燃料供应问题,需要对铀矿勘查方法进行深入研究。在实际勘探活动中,根据测量得到的地球物理异常特征确定矿体位置。传统的扩散对流理论认为氡气的迁移距离只有几十米,无法解释深部铀矿上方出现的氡异常。本论文对国内外有关铀矿地球物理勘探和氡运移的文章进行归纳和总结,研究了铀矿地球物理场特征和氡异常形成机理,最终得出以下结论:(1)铀矿主要分布在重力梯度带和低稳磁异常区,砂岩型铀矿对应的重力梯度带较宽缓,花岗岩型铀矿重力异常变化则较为陡急;铀矿的矿化层一般极化率高而电阻率较低,但古河道砂岩型铀矿矿体出现视电阻率偏高值异常,层间氧化带砂岩型铀矿矿体则位于自然电位曲线的拐点处。(2)地下水携带、地气等作用使得铀矿床上方可能存在三处铀富集区:分散晕区、潜水面铀富集区和地表地球化学障铀富集区。这三处铀富集区缩短了氡气向地表迁移的距离。氡运移的动力作用也不限于扩散对流作用,在深部还有团簇作用等,因此氡运移的迁移速度比单纯考虑扩散对流作用计算的要快。更短的迁移距离和更快的迁移速度,使得铀矿上方能够形成氡异常。(3)花岗岩、火山岩型铀矿有原生晕和次生晕,而砂岩型铀矿上方则不一定存在分散晕;花岗岩、火山岩型铀矿地表氡的高值异常出现在矿体正上方,砂岩型铀矿地表氡的高值异常出现在矿体两侧;与花岗岩、火山岩型铀矿相比较,砂岩型铀矿的地下水携带作用影响较弱,地气等作用的影响则相对较大。更多还原

【Abstract】 With the high-speed development of nuclear power station construction in China, the demand of uranium fuel also appears a rapid growth. The proven uranium reserves in China are limited. In order to solve the problem of nuclear fuel supply, it is necessary to research uranium exploration methods deeply. People determined the location of ore bodies according to the geophysical anomaly measured. The diffusive convection theory thinks that the migration distance of radon is only a few dozen meters, so it can not explain the radon anomaly above the deep uranium deposits. In this paper, I summarized the articles about uranium geophysical exploration and radon migration, studied on the characteristics of geophysical field in uranium deposits and the formation mechanism of radon anomaly, and ultimately reached the following conclusions:(1) Uranium deposits are mainly distributed at the gravity lineament and magnetic anomaly areas with gentle variations. The gravity anomaly varies stably at sandstone-type uranium deposits and varies greatly at granite-type uranium deposits. Uranium deposits usually have high polarizability and low resistivity, but the resistivity at paleochannel sandstone-type uranium deposits appears slightly high value anomaly. Interlayer oxidation zone sandstone-type uranium deposits locate at the inflexion of spontaneous potential curve. The wave impedance at sandstone-type uranium deposits is relatively high.(2) Actions of groundwater-carrier and geogas lead to 3 uranium concentration areas: dispersion halo area, groundwater table area,and geochemical barrier near earth surface. These uranium concentration areas shorten the migration distance of radon. The dynamic actions of radon migration are not limited to diffusion and convection. Because actions like clusters effect play a great role in deep subsurface, the real migration velocity of radon is faster than the calculation speed considering diffusion and convection merely.(3)There are primary halos and secondary halos in granite-type uranium deposits and volcanics-type uranium deposits, while the primary halos and secondary halos usually not exist in sandstone-type uranium deposits.High value surface anomaly of radon appears on the top of orebody in granite-type uranium deposits and volcanics-type uranium deposits,and appears on the edge of orebody in sandstone-type uranium deposits. Compared with granite-type uranium deposits and volcanics-type uranium deposits, influence of groundwater-carrier effect is relatively weak in sandstone-type uranium deposits.更多还原