作　　者： ; ; ; ; ;

机构地区： 中山大学海洋学院

出　　处： 《地质学报》 2015年第1期49-57,共9页

摘　　要： 通过野外和室内研究结果表明,罗田县片麻岩是由沉积岩变质而成.岩石化学成分变化范围：SiO2=61.25％～71.02％,Al2O3 =14.35％～15.48％、Na2 O＋K2 O=4.49％～6.09％和CaO=3.16％～4.80％等,表现为低铝、富碱、贫钙;富集Rb、Ba、Th、K等大离子亲石元素,P、Ti相对亏损;富集轻稀土（LREE/HREE=3.24～10.51）、略具Eu负异常（δEu=0.88～0.99）.稀土曲线呈轻稀土富集、重稀土亏损的向右倾式.在“CL”图像显示的锆石成因类型多为具有老核（继承锆石）新壳的变质复合锆石.老核继承锆石年龄从元古代—古生代,显示异地多时代的特点,表明其寄主岩的原岩沉积岩,时代不会早于古生代. Thegneiss in Luotian area are characterized by low A12O3 l（A12 03 = 14.35%- 15.48%）, alkali-rich （Na2Oq-K20 =4.49%-6. 09%） and low CaO （CaO=3.16%-4.80%）. They are further characterized by enrichment in large-ion lithophile elements such as Rb, Ba, Th and K and depletion in high field- strength elements such as P and Ti. The concentration of rare earth elements （REE） is in the range 170.51 X 10_6 -263.49 X 10-6. These rocks are enriched in light REE （LREE/HREE= 3.24-10.51） and lack of Eu negative anomaly （Eu = 0. 88-0. 99）. The REE distribution patterns are represented by right- inclined curves. CL images clearly show that most of the analyzed zircons are metamorphic composite zircons which have relict inner-cores and outer growth rims. Above all, a large number of allochthonous inherited zircon are formed in different times,which indicates the original rock of the Shiqiao gneiss should be sedimentary rocks and it may not be earlier than the Paleozoic era.

关 键 词： 元素地球化学 锆石 年龄 片麻岩 罗田县 湖北省

领　　域： [天文地球] [天文地球]