Isotope Geochemistry of the Dongchuan Copper Deposit,Yunnan,SW China： Stratigraphic Chronology and Application of Lead Isotopes in Geochemical Exploration

摘要

In this paper the Pb-Pb isochron method was used to determine the isotopic ages of te Luoxue Formation dolomites(1716±56Ma),th Heishan Formation carbonaceous slated (1607±128Ma) of the middle sub-group of the Kunyang Group and the Dayingpan Formation carbonaceous slates(1258±Ma) of the upper sub-group of the Kunyang Group.The age of the middle sub-group of the Kunyang Group is about 1800-1600Ma,belonging to the Late Paleo-Proterozoic,and that of the Dayingpan Formation in the upper sub-group of the Kunyang Group is about 1200-1300Ma, belonging to the Middle Poroterozoic.In addition,the Pb isotope chemical exploration techniques were used to study systematically the Pb isotopic compositions of rocks and ores across the No.14 vein in the middle segment of the No.1 pit of the Tangdan copper deposit and the result showed that the Pb isotope V1 values are neatively correlated with the copper contents.In is the first trial to use the systematic section method to conduct Pb isotope chemical exploration.