华北地台太古代绿岩型金矿床铅同位素特征及其在构造分区和矿床成因上的意义

Pb-ISOTOPIC CHARACTERISTICS OF ARCHEAN GREENSTONE TYPE Au-DEPOSITS IN THE NORTH CHINA PLATFORM AND THE IMPLICATION TO TECTONIC DIVISION AND THE GENESIS OF THE DEPOSITS

The North China Platform is one of the Au deposit-concentrated areas in China. Greenstone type Au deposits dominate other types. This paper presents Pb-isotopic data of greenstone type Au deposits in the North China Platform revealing a lower crust-mantle Pb isotope evolution trend. Au deposits associated with Archean strata (greenstone) and remelting granite are all characterized by low values of Pb isotope ratio and high values of model age. And their Pb isotope compositions are similar indicating that granite was formed by remelting of the Arcchean strata. Au deposits from different greenstone belts difer somewhat in their Pb isotope composition. This may be the just proof that they belong to different greenstone terrains. Au deposits of different genesis in the same greenstone belt are slightly different in Pb isotope composition.