Pb ISOTOPE COMPOSITION AND ORE-FORMING MATERIAL SOURCE OF DASHUI GOLD DEPOSIT IN GANSU PROVINCE

The paper attempt to trace the source of ore-forming material by studying Pb isotope composition both of ore and country rock in Dashui gold deposit.The research show that there are the similar Pb isotope range or narrow of little variation of between ore and rock,which imply the two came from a same Pb source.On the other hand,analysis from isotope tectonic pattern diagram and genetic classification of Δγ-Δβ reflect that Pb isotope has the characteristics of orogenic belt,subduction zone of crust and mantle mixture.It accounts for that Pb was not the product of sole source,but of mixture Pb of multi-sources.Therefore,the author supposed that the ore-forming material is multi-sources,both ore-formation and magmatic rock contributed Pb and ore-forming material,but magma took role as the first,and wall rock as the second,while Pb from mantle took part in the ore formation.