六盘山南段石嘴子花岗斑岩锆石SHRIMP U-Pb测年及其意义

Zircon SHRIMP U-Pb dating of granite porphyry at Shizuizi in southern section of Liupanshan and its significance

通过锆石SHRIMP U-Pb测年,获得了石嘴子花岗斑岩精度较高的同位素年龄值(1 778±14)Ma,厘定该岩体为中元古代早期(长城纪)侵入岩.根据区域对比,推测石嘴子花岗斑岩与长城纪海原岩群中的变质基性火山岩(原岩为辉绿岩)可能同属晋宁运动造山期后伸展体制下的产物.

By using SHRIMP U-Pb zircon dating, the accurate isotopic age of Shizuizi granite porphyry is obtained（1778±14）Ma, it proved that Shizuizi granite porphyry were formed in early Mcsoproterozoic （Changcheng period）. According to the regional comparison, it can be speculated that Shizuizi granite porphyry and metamorphic basic voleanies （protolith is diabase） from Changcheng Haiyuan group may be both belong to products of Jinning movement orogenic stretching regime.