滇西南云岭锡矿床地质特征与花岗岩锆石U-Pb年代学

滇西南是中国重要的锡矿带之一，前人研究主要集中在白垩纪和新生代花岗岩中的锡矿床，而对印支期花岗岩中的锡矿关注较少。云岭锡矿位于保山地块的东缘，矿体主要以脉状产在黑云母二长花岗岩中，发育云英岩化和电气石化蚀变。矿石矿物为锡石，脉石矿物为石英、白云母、电气石、萤石、方解石，以及黄铁矿、毒砂、黄铜矿、闪锌矿等硫化物。根据矿物共生组合以及脉体与蚀变的早晚关系，笔者厘定出4个热液成矿阶段，由早到晚分别为石英-电气石、石英-锡石-白云母-电气石、石英-钾长石±方解石、硫化物±石英阶段。云英岩化黑云母二长花岗岩中的锆石U-Pb年龄为(215.6±1.3)Ma，可近似代表云岭锡成矿时代。三叠纪锡成矿作用也发生在昌宁-孟连造山带的临沧岩基及东南亚锡矿带东部，该期成矿作用与古特提斯洋的演化有关。因此，中国滇西南三叠纪锡成矿作用与矿床保存的研究工作还需加强。

Geological characteristics and zircon U-Pb geochronology of granite in Yunling tin deposit, southwestern Yunnan

Southwestern Yunnan is one of important tin metallogenic belts in China. Previous studies mainly focused on tin deposits occurred in Cretaceous and Cenozoic granites, with less attention on tin deposits in Indosinian granites. The Yunling tin deposit is located in the eastern margin of the Baoshan block, ore bodies occur as veins in biotite monzogranite and are associated with greisenization and tourmalinzation. Ore mineral is cassiterite, and gangue minerals comprise quartz, tourmaline, muscovite, fluorite, calcite, pyrite, arsenopyrite, chalcopyrite, and sphalerite. According to mineral assemblages and relationship between hydrothermal veins and alteration, four hydrothermal mineralization stages are identified by author, from early to late including quartz-tourmaline, quartzcassiterite-muscovite-tourmaline, quartz-K-feldspar ± calcite, and sulfide ± quartz stage. LA-ICP-MS zircon UPb isotopic data of biotite monzogranite that was affected by greisenization yielded an age of(215.6 ± 1.3)Ma,which can approximately represent the mineralization age of the Yunling tin deposit. The Triassic tin mineralization also occurred in the Lincang batholith in the Changning-Menglian orogenic belt and in the eastern part of the southeast Asia tin belt, and was related to the evolution of the Paleo-Tethys ocean. Thus, it is necessary to strengthen the studies on ore-forming process and ore preservation of Triassic tin deposits in southwestern Yunnan.