云南武定迤纳厂铁铜矿岩浆角砾岩LA-ICP-MS锆石U-Pb年龄及其意义

    Zircon LA-ICP-MS dating of the magmatic breccia from the Yinachang iron-copper deposit in Wuding County of Yunnan Province and its geological significance

    • 摘要: 康滇地区是中国西南地区重要的元古宙铁铜成矿带。该地区元古宙昆阳群中串珠状分布岩浆角砾岩,周边分布大量铁铜矿床。选取武定迤纳厂东方红矿段穿插斜切入迤纳厂组的岩浆角砾岩,挑选胶结物中的岩浆锆石进行LA-ICP-MS测年,得到复合岩浆锆石内核207Pb/206Pb年龄为2193Ma±8Ma,代表深部围岩原生锆石年龄;岩浆锆石或复合岩浆锆石边缘环带207Pb/206Pb年龄为1739Ma±13Ma,代表岩浆侵位年龄;下交点年龄为980Ma±11Ma,代表变质年龄。结合相关资料判断,迤纳厂组与上昆阳群、大红山群、河口群均为1.7Ga左右昆阳板内裂谷拉张、岩浆侵位/喷发的同时异相产物。这对在滇中地区昆阳裂谷中,元古宙地层内的岩浆角砾岩周边寻找IOCG(IRON-OXIDE-COPPER-GOLD,铁氧化物-铜-金)型铁铜矿具有重要的启示。

       

      Abstract: Central Yunnan Province is an important Proterozoic iron-copper metallogenic belt in Southwest China. Magmatic breccia, accompanied with iron-copper deposits, occurs in Proterozoic Kunyang Group. To get the zircon LA-ICP-MS U-Pb age of the magmatic breccia, the authors collected the samples of magmatic breccias that obliquely penetrate the Yinachang Formation in the Yinachang deposit of Wuding County, and selected the magmatic zircon from the cement. The core of the zircon has an average weighted 207Pb/206Pb age of 2193Ma±8Ma, which represents the age of primary zircon from the depth. The outer zones of the zircon have an average weighted 207Pb/206Pb age of 1739Ma±13Ma, representing the formation age of the magma. The metamorphic age of the breccia is 980Ma±11Ma. In combination with related data, the authors believe that the strata of the Yinachang Formation, the Upper Kunyang Group, the Dahongshan Group and the Hekou Group are contemporary products of the magmatic activity during the intraplate extension. This discovery has an important inspiration in search for IOCG type deposits around the magmatic breccia in the Proterozoic strata within the Kunyang rift of central Yunnan Province.

       

    /

    返回文章
    返回