冀北大滩盆地钾玄岩系列的厘定、岩石成因及与铀成矿关系  

Determination,petrogenesis and relationship with uranium mineralization of shoshonite series in Datan Basin,northern Hebei

作　　者：高天栋[1] 郭恒飞 姜山[1] 巫建华[2] 牛子良 王洪志[1] 王之晟 马国祥[1] GAO Tiandong;GUO Hengfei;JIANG Shan;WU Jianhua;NIU Ziliang;WANG Hongzhi;WANG Zhisheng;MA Guoxiang(No.243 Geological Party of Nuclear Industry,CNNC,Chifeng,Inner Mongolia,024000;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang,330013)

机构地区：[1]核工业二四三大队,内蒙古赤峰024000 [2]东华理工大学核资源与环境国家重点实验室,南昌330013

出　　处：《地质论评》2023年第2期573-590,共18页Geological Review

基　　金：中国核工业地质局铀资源调查评价项目(编号:201933-4)的成果。

摘　　要：大滩盆地位于华北克拉通北缘隆起带和沽源—红山子铀成矿带西南段,盆地内五里营铀矿点赋存在义县期(早白垩世晚期)二长斑岩中。二长斑岩全岩为高钾、富碱、低钛、贫铁,富集轻稀土元素和大离子亲石元素,无明显Eu负异常,具有碱性系列和钙碱性系列的特征,属典型的钾玄岩系列;[n(^(87)Sr)/n(^(86)Sr)]_(i)为0.707290~0.707399(平均值为0.707343),[n(^(143)Nd)/n(^(144)Nd)]_(i)为0.511849~0.511895(平均值为0.511876),ε_(Nd)(t)值变化范围是-12.38~-11.49,[n(^(206)Pb)/n(^(204)Pb)]_(i)为17.236~17.343(平均值17.296),[n(^(207)Pb)/n(^(204)Pb)]_(i)为15.407~15.428(平均值为15.416),[n(^(208)Pb)/n(^(204)Pb)]_(i)为37.666~37.707(平均值为37.684)。ε_(Nd)(t)—[n(^(87)Sr)/n(^(86)Sr)]_(i)、[n(^(143)Nd)/n(^(144)Nd)]_(i)—[n(^(87)Sr)/n(^(86)Sr)]_(i)、[n(^(207)Pb)/n(^(204)Pb)]_(i)—[n(^(206)Pb)/n(^(204)Pb)]_(i)和[n(^(208)Pb)/n(^(204)Pb)]_(i)—[n(^(206)Pb)/n(^(204)Pb)]_(i)图解显示岩浆来源与EMⅠ富集地幔密切相关,可能还有下地壳组分的参与。受太平洋板块洋壳俯冲和华北克拉通岩石圈拆沉的双重影响,其构造环境为拉伸环境,岩浆主要源于加厚陆壳底部物质的部分熔融。五里营铀矿化与下庄矿田“交点型”铀矿床成矿特征相似,赋存于一系列NNW向硅化、青磐岩化蚀变带内,其赋矿围岩二长斑岩(钾玄岩系列)所具备的富集地幔印记制约着U等大离子亲石元素的富集。Objectives:The Datan basin is situated in the uplift belt of the northern margin of the North China Craton and the southwest section of the Guyuan—Hongshanzi uranium metallogenic belt.A number of uranium occurrences and uranium anomaly site have been newly discovered in the Wuliying area of the basin.They mainly occurs in the middle—basic subvolcanic rocks of the Yixian period,and the geological age belongs to the late Early Cretaceous,which is obviously different from the known ore-bearing horizons in this metallogenic belt——the Zhangjiakou Formation high-potassium calc-alkaline rhyolite in the early Early Cretaceous.The rock——alkaline trachyte assemblage and the high-potassium calc-alkaline—alkaline rhyolite assemblage of the Xinmin Formation in the early Late Jurassic.However,there is still a lack of systematic research on lithology,petrography,geochemical characteristics and petrogenesis in this ore-bearing layer.Methods:Based on detailed observations of occurrence of Wuliying uranium occurrences in the field,we have studied the petrology,geochemistry,Sr—Nd—Pb radio isotope of host rocks to discuss nature of source region and tectonic setting,than,we have discussed the relationship between middle—basic subvolcanic rocks and uranium mineralization.Results:The host rock is ivernite.All of ivernites are characterized by high contents of K_(2)O and total alkali,low contents of TiO_(2)and iron,and an enrichment of LREE and LILE element.It has the characteristics of alkaline series and calc alkaline series,and belongs to the typical shoshonite series.[n(^(87)Sr)/n(^(86)Sr)]_i between 0.707290 and 0.707399(the average is 0.707343),[n(^(143)Nd)/n(^(144)Nd)]ibetween 0.511849 and 0.511895(the average is 0.511876),ε_(Nd)(t)range of-12.38~-11.49,[n(^(206)Pb)/n(^(204)Pb)]i between 17.236 and17.343(the average is 17.296),[n(^(207)Pb)/n(^(204)Pb)]i between 15.407 and 15.428(the average is 15.416),[n(^(208)Pb)/n(^(204)Pb)]ibetween 37.666 and 37.707(the average is 37.684).In theε_(Nd)(t)—[n(^(87)Sr)/n(

关 键 词：钾玄岩系列 EM I富集地幔 构造环境 铀成矿 大滩盆地 

分 类 号：P619.14[天文地球—矿床学]