Rock-forming and Ore-forming Ages of the Yanbei Porphyry Tin Deposit in Jiangxi Province and Their Geological Significance

Abstract

Located in western Wuyi Mountain within Huichang County of Jiangxi Province,the Yanbei tin deposit with rich original topaz is the only large-sized tin deposit so far discovered in the study area.Isotopic chronological study of the tin-bearing granite-porphyry and quartz-topaz-cassiterite veins formed at the early ore-forming stage shows that the quartz-topaz-cassiterite veins have a quartz fluid-inclusion Rb-Sr isochron age of(125.5±6.1) Ma(2σ,MSWD=1.5,Ir=0.7130±0.0050),which accords with the whole-rock Rb-Sr isochron age((128.1±3.3) Ma,2σ,MSWD=1.07,Ir=0.7163±0.0052) of the granite-porphyry.It is thus concluded that the rock-forming and ore-forming activities of the Yanbei tin deposit occurred during the early Cretaceous episode,with the mineralization closely related to the post-volcanic high-level emplaced granite-porphyry.