论文部分内容阅读
针对黔西普安铅锌矿区内的辉绿岩脉进行锆石U-Pb年代学与地球化学研究,结果表明其主量元素以高w(TiO2)(4.12%~4.18%)、高w(CaO)(7.46%~8.63%)和低w(MgO)(4.59%~5.02%)、低碱且Na2O>K2O为特征,ΣREE总量较高,LREE明显富集。与原始地幔相比,明显富集Rb,Ba,Th等大离子亲石元素,而高场强元素(HFSE)Nb,Zr,Hf等略为亏损,并出现K,Sr和P亏损。主量元素特征和微量元素标准化图解显示,普安辉绿岩属于拉斑玄武岩系列,具有洋岛玄武岩(OIB)的特征,与峨眉山玄武岩为同源产物,具有密切的成因关系。微量元素示踪表明,岩浆来源于富集地幔,具有地幔柱成因特征。LA-ICP-MS锆石U-Pb定年结果表明辉绿岩形成年龄为263 Ma±10 Ma,代表了峨眉山地幔柱的启动时间。
The zircon U-Pb geochronology and geochemistry of diabase dikes in Pu’an lead-zinc mining area in western Guizhou Province are studied. The results show that the major elements are characterized by high w (TiO2) (4.12% -4.18%) and high w (7.46% ~ 8.63%) and low w (MgO) (4.59% ~ 5.02%), with low alkali and Na2O> K2O. The total amount of ΣREE is higher and the LREE is obviously enriched. Compared with the original mantle, it is obviously enriched in large ion lithophile elements such as Rb, Ba and Th, while Nb, Zr and Hf in high field strength element (HFSE) are slightly depleted and K, Sr and P losses occur. The main elemental characteristics and trace elements standardization diagram shows that the diabase belongs to tholeiite series, with the characteristics of ocean island basalts (OIB), and Emeishan basalt is a homologous product, has a close genetic relationship. Trace trace elements show that magma is derived from enriched mantle and has mantle plume origin. U-Pb zircon dating from LA-ICP-MS shows that the formation age of diabase is 263 Ma ± 10 Ma, representing the start-up time of the Emei Mountain mantle plume.