摘要
华北地台南缘金矿带的矿石铅和燕山期花岗岩岩石铅与太华群岩石铅极为相似,μ,ω和Th/U比值都较低,其中矿石铅为多阶段铅。矿石铅和花岗岩岩石铅在^(207)Pb/^(204)Pb-^(206)Pb/^(204)Pb图上位于上地幔和下地壳铅演化线之间,表明它们来自具低U和Th/U比值的深部源区(太华群)。所有矿床的矿石铅均可拟合成具不同斜率的二次等时线,这证明矿石铅是在不同时代从一个统一的源区(太华群)分离并沉淀成矿的,同时受到壳源铅的混染。这充分证明了成矿的多期性和复杂性以及成因的多重性,但仍以变质成因为主。本文还讨论了铅模式年龄的意义。
The lead isotopes in the gold deposits which is multiphase, Yanshaniangranites and the Archean matemorphic rocks of Taihua Group along south marginof North China Platform are very similar, and their μ, ω and Th/U ratios arevery low. This suggests they come from a deep source with low and Th/U ratio(Taihua Group). Ore lead isotopes in every deposit could fit a quadraticisochrpne, which indicates the isotopes separate from a unified source andconcentrate to form gold deposits and are contaminated by lead isotopes fromthe crust at different times. The isotopes prove that metallization is complexand polyphase, and that the origin of deposits is multiple. Authors-also discussthe model ages of lead isotopes, which have no significant dating and indicationin geology.
关键词
金矿带
铅
同位素
lead isotope
gold deposit belt
south margin of North China Platform
