个旧锡铜多金属矿田东、西矿区剥露程度的对比研究-低温热年代学证据

The Gejiu Sn-Cu polymetallic deposit in Yunnan province is the largest intrusion-related tin deposit in the world. It can be divided into eastern and western segments by the Gejiu fault. Over 90% metal reserves are concentrated in the eastern segment in 600 km2 area. In contrast, less than 10% reserves are estimated in the western segment, although which takes much larger area of 1100 km2 and occurred much stronger magmatic activities. Many geochronological and geochemical studies have carried out on the eastern segment. However, the reason of why relatively larger area of the western segment hosting less metals is not clear. In this study, we focus on widespread, mineralization-related granite in both segments in the Gejiu area. Using apatite and zircon fission-tracks and (U-Th)/He dating techniques, we aim to reveal granite cooling and erosion rate variations between the eastern and western segment. In combination with in-situ LA-ICP-MS analyses of apatite and zircon, we try to better understand difference of magma evolution history between two segments, which may be genetically contributed discordant mineralization patterns in the Gejiu area. This study will not only benefit to better understand ore-forming processes, but will also help for explorations in Gejiu, especially in western segment of the Gejiu area.

云南个旧是世界上最大的锡铜多金属矿田。以个旧断裂为界分为东、西两个矿区，其中东区(面积约600 km2)汇集了个旧地区金属总储量的90%以上，而面积约1100 km2且岩浆岩大面积出露的西区，其金属总储量不足10%。在以往研究中，对个旧东西区成矿差异如此巨大的事实尚缺乏针对性的研究。本项目将以个旧矿田中与成矿作用关系密切的花岗岩为研究对象，拟通过磷灰石和锆石的(U-Th)/He定年及裂变径迹定年对个旧东西矿区岩体剥露和冷却历史进行计算。并对磷灰石和锆石进行LA-ICP-MS的微量元素分析，结合已有的地质和地球化学研究成果深入分析东西矿区在岩浆演化上的差异。综合低温热年代学研究和单矿物的微量元素研究，探讨剥露程度和岩浆演化的差异对东西区成矿的影响，进而为个旧地区，尤其是西区的找矿勘探提供建议。