Zhenyuan gold deposit is the largest super large gold deposit in the Ailaoshan gold belt,but its precise mineralization age is still lack.Re-Os isotopic age of the auriferous pyrite from the Zhenyuan gold deposit was determined by using a high-resolution inductively coupled plasma mass spectrometry(HR-ICP-MS).The pyrite samples were decomposed in carius tubes,Os was separated by distillation and Re was extracted by acetone,respectively.The results show that the Re-Os isochron age is 229±38 Ma(MSWD=2.0,confidence level is 95%),with an initial 187 Os/188 Os value of 0.68±0.24 and a corresponding Os value of 442±91.The Re/Os ratios of the pyrite vary from 40.8 to 100.5.The data suggest that at least one important ore-forming event was occurred during Indosinian epoch,and the ore-forming materials probably derived from mixed sources of crustal and mantle,while the later dominated.The Ailaoshan composite orogen experienced complicated evolutional processes,including formation of Precambrian-Early Paleozoic basement,subduction and orogenesis of Late Paleozoic era,collisional orogenesis of Late Hercynian-Indosinain epoch,and extensional or striking orogenesis of Yanshainan-Cenozoic epoch.The polycycle tectonic evolution and magmatism in this area caused multi-stage and superposition metallization characteristics of the Zhenyuan gold deposit:the mineralization probably occur mainly during the Indosinian collisional orogeny,while the minor gold ores of altered granite-porphyry and altered lamprophyre may be formed in the late superposition metallization.
SHI GuiYongSUN XiaoMingPAN WeiJianHU BeiMingQU WenJunDU AnDaoLI Chao
国际上流行的造山型金矿理论主要是在前寒武古老克拉通剪切带型金矿基础上发展起来的(Groves et al.,1998;Goldfarb et al.,2001)。流行观点认为:造山型金矿主要发育在增生造山带,而碰撞造山带似乎不利于成矿(Barley et al.,1992;Groves et al.,1998;Kerrich et al.,2000)。然而,我国西南地区喜马拉雅期造山型金矿大量发育,至少形成了3条重要的Au矿带,即滇西哀牢山Au矿带(Sun et al.,2009)
