基于多道伽马能谱测量的离子吸附型稀土矿放射性勘查方法研究——以攀西德昌地区为例

An exploration method for the radiation of ion adsorption-type rare earthelement deposits based on multi-channel gamma-ray spectrometry:A case study of the Dechang area in the Panzhihua-Xichang region

冕宁—德昌稀土成矿带资源潜力大,以往的找矿方向集中在寻找与喜马拉雅期碱性杂岩有关的硬岩型稀土矿,对离子吸附型稀土矿的研究程度较浅。为探究区内广泛分布的花岗岩风化壳的成矿前景,以区内狮子山地区为研究对象,部署多道伽马能谱测量、土壤剖面测量和浅钻工程,在摩所营花岗岩风化壳中圈定1处离子吸附型稀土矿点。对地、物、化剖面及含矿量的放射性响应进行分析,发现Th与K含量对稀土稀有矿化具有较高的指示意义,当6.2537×10^(-6),w(K)>4.2%时,就可能出现矿化好、具有工业规模的离子吸附型稀土矿。从放射性异常对表生风化的响应特征分析,钍异常晕对花岗岩岩体具有较好的指示作用,钾异常晕能较好地圈定花岗岩风化壳的范围。

The Mianning-Dechang rare earth element(REE)metallogenic belt exhibits considerable resource potential.Previous prospecting was oriented to hard-rock REE deposits associated with Himalayan alkaline complexes,with ion adsorption-type REE deposits under-studied.To explore the mineralization prospect of granite weathering crusts widespread in the metallogenic belt,this study investigated the Shizishan area through multi-channel gamma-ray spectrometry,soil profile survey,and shallow drilling.One ion adsorption-type REE ore occurrence was identified in the granite weathering crust at Mosuoying.This study analyzed the radioactive response of the geological,geophysical,and geochemical profiles and ore contents,finding that the elemental contents of thorium(Th)and potassium(K)were highly indicative of REE and rare metal mineralization.Highly mineralized,industrial-scale ion adsorption-type REE deposits will likely occur when 6.25<w(Th)/w(K)<10,w(eTh)>37×10^(-6),and w(eK)>4.2%.As revealed by the analysis of the response of radioactive anomalies to supergene weathering,thorium anomaly halos can effectively indicate granitic plutons while potassium anomaly halos can well delineate the extent of granite weathering crusts.