龙首山芨岭地区基性岩脉地球化学特征及其地质意义  

Geochemical Characteristics of Basic Dikes from Jiling Area in Longshoushan and Its Geological Significance

作　　者：张良 张树明[2,3] 魏正宇[4] 胡菲菲[1] 陈云杰 

机构地区：[1]核工业二〇三研究所,陕西咸阳712000 [2]东华理工大学核资源与环境省部共建国家重点实验室培育基地,江西南昌330013 [3]东华理工大学放射性地质与勘探技术国防重点学科实验室,江西南昌330013 [4]中国冶金地质总局山东正元地质勘查院,山东济南250101

出　　处：《西北地质》2017年第4期23-32,共10页Northwestern Geology

基　　金：国家自然科学基金项目"龙首山产于花岗岩中的碱交代型铀矿床成矿机理研究"(41172079);中国地质调查局项目"北秦岭成矿带东段夜村-庾家河地区铀矿资源调查评价"(DD2016013623);中国核工业地质局项目"陕西省北秦岭成矿带铀资源评价与勘察"(201621)

摘　　要：以甘肃省龙首山芨岭地区基性岩脉为研究对象,在研究基性岩脉地球化学特征基础上,探讨其岩浆源区特征及演化过程。该区基性岩脉SiO_2为47.09%~51.13%;具有高Al(Al_2O_3为14.56%~15.97%)、富Na(Na_2O为3.35%~3.69%)、低K(K_2O为0.347%~1.23%)的特征。稀土总量较低(105.7×10^(-6)~186.97×10^(-6)),稀土配分模式为右倾轻稀土富集型((La/Yb)N=4.50~9.63)。富集元素Ba、U、Pb、P、Ti,亏损元素Rb、Th、K,属拉斑玄武岩系列。基性岩脉形成于板内拉张环境,经历了以橄榄石、单斜辉石、Ti-Fe氧化物为主的分离结晶作用;岩浆上升过程中基本未受到地壳物质的混染。其原岩岩浆是地幔岩部分熔融后,经地幔交代作用形成的熔体。基性岩脉岩浆产生于过渡型地幔源区,源区为尖晶石+石榴子石二辉橄榄岩地幔。The mafic dikes from Jiling area in Longshoushan has selected been as the study object, and the magmatic source characteristics and evolutionary processhas been discussed in this paper. SiO2 content of mafic dikes in Jiling area is 47 09%-51 13%. They are characterized by high aluminum （Al2O3=14 56%-15 97%）,rich sodium （Na2O=3 35%-3 69%） and low potassium （K2O=0 347%-1 23%）. The ∑ REE（105 7×10^-6-186 97×10^-6）is relative low with the right type of LREE distribution patterns（（La/Yb）N=4 50-9 63）. These mafic dikes have a characteristic of rich Ba, U, Pb, P and Ti and depleted Rb, Th and K, belonging to the tholeiite series. They were formed in extensional intraplateenvironment and experienced fractional crystallization of olivine, clinopyroxene and TiFe oxides.The magma hadnt been contaminated by crustal materials during its ascent process. Its original magma was derived from the melt of the pyrolite which was formed by the mantle metasomatism after the partial melting. Thus, the magma of mafic dikes was derived from transitional mantle source region,with the source of spinel ＋ garnet lherzolite mantle. Keywords：Jiling; mafic dikes; geochemical characteristics; source region （1 No 203 Research Institute of Nuclear Industry, Xianyang 712000, Shaanxi, China; 2 State Key Laboratory Breeding Base of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013, Jiangxi, China; 3 Fundamental Science on Radioactive Geology and Exploration Technology Laboratory, East China University of Technology, Nanchang 330013, Jiangxi, China; 4 Geological Exploration Institute of Shandong Zhengyuan, Jinan 250101, Shandong, China） Abstract：The mafic dikes from Jiling area in Longshoushan has selected been as the study object, and the magmatic source characteristics and evolutionary processhas been discussed in this paper. SiO2 content of mafic dikes in Jiling area is 47 09%-51 13%. They are characterized by high aluminum （Al2O3=14 56%-1

关 键 词：芨岭 基性岩脉 地球化学特征 源区 

分 类 号：P595[天文地球—地球化学]