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

 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 carrier 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.