山西省临县紫金山地区U、Th、K三种放射性元素特征分析

Characteristics of Three Radioactive Elements in U, Th and K in Zijinshan Region, Linxian County, Shanxi Province

为了研究山西临县紫金山地区放射性矿产铀、钍、钾元素异常分布规律、含量、赋存状态,通过运用地面伽马能谱和显微镜镜下分析二者相结合的方法研究了研究区内的岩石,得到紫金山地区岩石的铀、钍、钾放射性参数和铀、钍、钾异常对应岩石的镜下分析结果。结果表明:山西临县紫金山地区铀、钍元素异常主要分布在黑云辉石岩、霞石正长岩中,它是由于这二种岩石中分布的磷灰石和榍石所以引起的,榍石和磷灰石占黑云辉石岩总量的7%~11%,榍石在霞石正长岩中的含量占总量的1%~5%;钾异常主要分布在黑云母辉石正长岩中,钾元素异常是由黑云母辉石正长岩中的正长石引起的,黑云母辉石正长岩中的正长石占整体的85%~90%。可见通过地面伽马能谱和显微镜镜下分析二者相结合的方法可以解释山西省紫金山地区放射性矿产铀、钍、钾异常分布规律、含量、赋存状态。综上,黑云辉石岩、霞石正长岩、黑云母辉石正长岩为今后放射性矿产突破所在,建议在区部署地面伽玛能谱扫面工作,再对扫面工作的异常区进行槽探及钻探工程验证。

To study the distribution, abundance, and occurrence of high abnormal abyndance of uranium, thorium, and potassium in radioactive minerals in Zijinshan area, Linxian, Shanxi Province. The local rocks were investigated using ground gamma ray spectroscope in microscopic analysis, and the radioactive parameters of uranium, thorium, and potassium and the results of microscopic analysis were obtained. Results show that high abnormal abundance of uranium and thorium in the study region were mainly related to and resulted from sphene and apatite hosted in biotite pyroxenite and nepheline syenite. The contents of sphene and apatite accounted for 7%~11% of the total amount of biotite pyroxenolite, and that of sphene for 1%~5% of nepheline syenite. High potassium anomaly was found in biotite pyroxene syenite due to the existence of orthoclase accounting for 85%~90% of the whole rock. It was concluded that the combination of the ground gamma spectroscopy and microscopic analysis could explain the high abnormal distributions of uranium, thorium, and potassium in radioactive minerals in the study region, and that biotite pyroxenolite, nepheline syenite, and biotite pyroxene syenite could be the future targets of exploration for radioactive mineral production. Therefore, ground gamma ray spectrum sweeping in the study region is recommended, plus necessary trenching and drilling works.