贵州省普安矿区17号煤层中Au的富集成因研究

Mechanism of gold accumulation of No.17 coal seam in Pu'an coalfield,Guizhou Province

运用中子活化分析（INAA）、带能谱的扫描电镜（SEM-EDX）和电子探针（EMPA）研究了贵州省普安矿区17号煤层刻槽样中Au元素的含量、分布特征、赋存状态及富集机理。结果表明,17号煤层中Au的质量分数为2.61×10^-9-9.73×10^-9,平均6.29×10^-9,大于世界煤和中国煤中Au的平均含量;煤中Au主要以矿物吸附态存在,载体矿物为黄铁矿和黏土矿物;17号煤层Au的物质来源为低温热液流体;在低温热液流体沿断裂带进入煤层的过程中,受到疏松多孔的煤层吸附而使Au元素发生沉淀,加之17号煤层沉积环境为较为封闭的浅海环境的综合作用而富集在煤中。Au的富集类型为深大断裂-热液作用富集型。

The concentration, distribution occurrence modes of gold and mechanism of its accumulation in No. 17 coal seam of Pu＇an coalfield, Guizhou Province were studied using neutron-activation method （INAA）, scanning electron microscope with an energy-dispersive X-ray （SEM-EDX） and electron probe analysis （EMPA）. The results show that the content of gold in the No. 17 coal seam is 2.61 ×10-9 -9.73×10-9, with the mean value （6.29×10-9） higher than that in coals from China and the world. The gold in coal mainly exists in form of inorganic mineral. The cartier minerals are pyrite and clay. The source of gold is epigenetic hydrothermal, which can be captured by the loose and porous coal seam. In addition, closed hallow sea environment provides favorable conditions for gold accumulation. Deep fault-hydrothermal process is the mainly type of gold accumulation in the No. 17 coal seam.