Isotopic Dating and Geological Significance of Stratiform Orebody in Gejiu Tin Deposit, Yunnan, China

摘要

Gejiu tin ore deposit is a famous tin-polymetallic deposit in the world because of its enormous metal reserves. Besides tin, there are copper, lead, zinc, silver, iron, sulphur, tungsten, bismuth, indium and rare earth elements. It was believed that there mainly are skarn-type tin deposit, stratiform tin deposit and basalt-type copper deposit in Gejiu tin orefield. The stratiform tin deposit are distributed in Lutangba, Malage and Huangmaoshan, which are hosted by carbonate rocks of Gejiu formation in Middle Triassic Series. 40Ar-39Ar dating of cassiterite from the sratiform tin deposit in Lutangba yields plateau age of 202.18±2.35Ma and isochron age of 206.81±3.23 Ma respectively. The ages are obviously older than those of the ore of the skarn type deposit of the Yanshanian epoch．The mineralization is the seabed exhalative hydrothermal sedimentary mineralization of the Indosinia epoch.