桂北罗城垒洞煌斑岩LA-ICP-MS锆石U-Pb定年及其地质意义  

LA-ICP-MS ziron U-Pb dating of the lamprophyres from Leidong in Luocheng,northern Guangxi and its geological implications

作　　者：郭智超[1,2] 时毓 王新宇[3] 付伟 刘希军 覃康乐[1,2] 刘磊 GUO Zhi-chao;SHI Yu;WANG Xin-yu;FU Wei;LIU Xi-jun;QIN Kang-le;LIU Lei(a.Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration;b.Guangxi Collaborative Innovation Centre of Hidden Non-Ferrous Metallic Ore Deposits Exploration and Development of Materias,Guilin University of Technology,Guilin 541004,Chin;2.Guangxi General Instituste of Geology and Exploration,Nanning 530023,China)

机构地区：[1]桂林理工大学广西隐伏金属矿产勘查重点实验室,广西桂林541004 [2]桂林理工大学广西有色金属隐伏矿床勘查及材料开发协同创新中心,广西桂林541004 [3]广西壮族自治区地质勘查总院,南宁530023

出　　处：《桂林理工大学学报》2018年第2期208-216,共9页Journal of Guilin University of Technology

基　　金：国家自然科学基金项目(41562005);广西自然科学基金项目(2016GXNSFAA380001)

摘　　要：利用LA-ICP-MS法对桂北罗城垒洞煌斑岩中的锆石进行了U-Pb同位素定年。所分析的锆石晶形有的呈自形柱状,有的呈浑圆-椭圆状,少数锆石具有核-幔结构,阴极发光(CL)图像显示其有明显的震荡环带,符合岩浆锆石特征。锆石U-Pb同位素年龄主要集中在830和810 Ma,与江南造山带变质基底四堡群和丹洲群的形成年龄基本一致,暗示这些锆石可能为来自四堡群和丹洲群地层中的捕获锆石或继承锆石。形成于830 Ma左右的锆石与侵入于四堡群的花岗岩类岩石可能为同一次构造事件的产物,也可能为这些花岗岩类岩石中的捕获锆石或继承锆石;179±2 Ma的锆石年龄(晚中生代燕山早期)则很可能代表了煌斑岩的变质年龄。This study reported the LA-ICP-MS zircon U-Pb ages of the lamprophyres from Leidong of Luocheng in northern Guangxi. The zircon grains are euheadral or sub-rounded,with some core-rim structure,and exhibit obvious oscillatory under cathodoluminescence,showing that they are of magmatic origins. The zircon U-Pb ages mainly concentrated in 830 Ma and 810 Ma,similar to the ages of Sibao and Danzhou Groups in Jiangnan Orogen,which were probably captured or inherited from these two Groups. Zircons formed in ~ 830 Ma in this study are probably the products of the same tectonic event as the igneous rocks in the Jiangnan orogeny or captured（ or inherited） from these igneous rocks. Two metamorphic zircon mean age of 179 ± 2 Ma suggested that the lamprophyres might endure the metamorphism in Early Yanshanian.

关 键 词：煌斑岩 年代学 新元古代 桂北 江南造山带 

分 类 号：P588.13[天文地球—岩石学] P597.3[天文地球—地质学]