湖南宁乡钾镁煌斑岩及相关岩石重砂锆石地球化学特征、U-Pb年龄及其地质意义  

Geochemistry and U-Pb Dating of Heavy Mineral Zircons and Their Significance in Lamproites and Associated Rocks from Ningxiang,Hunan Province

作　　者：林玮鹏[1,2] 丘志力[1] 董斌[3] 梁伟章[4] 陈华[5] 李子云[3] 陈炳辉[1] 李榴芬[1] 

机构地区：[1]中山大学地球科学系,广东广州510275 [2]广东省有色金属地质勘查局地质勘查研究院,广东广州510080 [3]湖南省地质矿产勘查开发局413队,湖南常德415000 [4]广州出入境检验检疫局,广东广州510235 [5]国土资源部珠宝首饰管理中心,北京100013

出　　处：《中山大学学报（自然科学版）》2011年第3期105-111,共7页Acta Scientiarum Naturalium Universitatis Sunyatseni

基　　金：国家自然科学基金资助项目(40673039);国家质检总局科研基金资助项目(2007IK006);国土资源部公益性行业科研基金资助项目(200811012)

摘　　要：对湖南宁乡等地多个含有金刚石的钾镁煌斑岩及相关岩石的重砂矿物进行了分离,利用电子探针、阴极发光图像及LA-ICPMS等对其中的锆石进行了主微量元素成分、内部结构及U-Pb同位素年龄的分析。结果表明,不同地点钾镁煌斑岩重砂锆石的地球化学特征具有一定相似性;与钾镁煌斑岩有关锆石的U-Pb年龄显示研究区的岩浆活动具有多期次的特点,其中宁乡Ⅰ号及Ⅲ号岩管钾镁煌斑岩4颗重砂锆石的206Pb/238U加权平均年龄为(101.6±5.1)Ma,显示出较为年轻的特点,但石门上五通地区白垩系红层中也发现具有207Pb/206Pb谐和年龄为(2 008±29)Ma古老岩浆结晶锆石的存在,证实该地和金刚石有关火山物质的来源具有复杂性。Heavy mineral zircons were separated from diamondiferous lamproites and their associated rocks in Ningxiang and nearby area,Hunan province,and their main and trace element compositions,interior structure and the U-Pb isotopic ages were obtained with EPMA,cathodoluminescence microscope and LA-ICPMS measurement.The zircons in lamproites from different locations generally have similar geochemical characteristics.The U-Pb dating of zircons suggests that the lamproites were probably formed during multi-stages.A young age of（101.6±5.1）Ma was obtained on four zircon samples from No.1 and No.3 pipe lamproites.The zircon collected from the Cretaceous red strata in Shangwutong area has a concordant 207Pb/ 206Pb age of（2 008±29）Ma.These results cannot specifically determine the source rocks of diamond in the study area.

关 键 词：钾镁煌斑岩 重砂矿物 锆石 微量元素 U-PB年龄 湖南宁乡 

分 类 号：P597[天文地球—地球化学]