康定杂岩时代及成因探讨

THE STUDY ON THE AGE AND ORIGIN OF THE KANGDING COMPLEX

康定杂岩是康滇地轴上一套复杂岩系,由紫苏辉长质暗色杂岩、英云闪长质浅色杂岩及复成分混合杂岩构成。岩石结构构造,铀、钍及稀土特征表明,主体为岩浆杂岩,包含大量具层状痕迹的变质杂岩。大量的锆石U-Pb年龄及其它同位素年龄表明,岩浆岩属晋宁-澄江期。变质杂岩时代与河口群相当。而河口群具有下元古界典型的磁铁石英岩、基性火山岩、硅质石墨片岩岩石组合,且有同位素年龄佐证。因此,原康定杂岩由下元古界变质杂岩及晋宁-澄江期岩浆杂岩组成。

The Kangding complex is a complex rock series in the Kangding axis. It consists of dark hy-persthenic complex, gray tonalitic complex and mixed complex. The textures and structures of the rocks and U-Th and REE features indicates that the main body of the Kangding complex is represented by magmatic complex, including a large amount of layered metamorphic complex. A lot of zircon U-Pb ages and other isotopic ages indicate that the magmatic complex is of Jinningian-Chengjiangian age. The age of metamorphic complex is the same as that of the Hekou Group. The Hekou Group contains magnetite quartzite, basic volcanic rocks and siliceous graphite schist of the Lower Proterozoic, and its Early Proterozoic age has been evidenced by isotopic dating. Therefore the Kangding complex consists of the Lower Proterozoic metamorphic complex and Jinningian-Chengjiangian magmatic complex.