The modes of gold-migration in the gossan-type gold deposit

摘要

More than 30 gossan-type gold deposits have beed discovered in the Middle-Lower Yangtze River Area. The profile of gold-bearing gossan can be divided into four subzones from upper to lower:(i) gold-deficient or gold-leached gossan (Au contents (0.1-0.8)x10~(-6) transitonal subzone; (ii) secondary gold concentration subzone (Au (4-20)x10~(-6); (iii) oxide and sulfide transitional subzone (Au (0.5-1.5)x10~(-6); (iv) Primary sulfide ore (Au(0.5-1)x`0~(-6). Au Concentration in the subzone (ii) is 2-20 times higher than that in subzone (IV). Obviously migration and secondary concentration of Au had happened in the process of oxidationof primary sulfides.