摘要
华北地台是我国最重要的原生金矿产地,主要金矿类型是与太古代变基性火山岩(绿岩)有关的绿岩型金矿.本文对华北地台太古代绿岩型金矿床铅同位素组成进行了研究,认为铅同位素组成具有下地壳-地幔铅的演化特征.无论是太古代地层,还是重熔花岗岩及有关的金矿床,都具有低比值、低μ值、大模式年龄的特征.太古代地层(绿岩)、交代重熔花岗岩、绿岩型金矿三者铅同位素组成十分相似,揭示了一脉相承的演化关系,即花岗岩由太古代地层重熔形成,金矿成矿物质也来自太古代地层(绿岩).不同绿岩带的绿岩型金矿铅同位素组成有一定的差异,反映这些绿岩带应分属不同的绿岩地体.在同一绿岩地体,不同成因的金矿床铅同位素比值也略有不同.
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.
出处
《地质找矿论丛》
CAS
CSCD
1992年第4期75-84,共10页
Contributions to Geology and Mineral Resources Research
