粤北坪下水地区辉绿岩地球化学特征及其成因  

Geochemical Characteristics and Genesis of Diabase in Pingxiashui Area of Northern Guangdong,China

作　　者：郭新文 梁园园 赖静 周航兵 江卫兵[1] GUO Xinwen;LIANG Yuanyuan;LAI Jing;ZHOU Hangbing;JIANG Weibing(Research Institute No.290,CNNC,Shaoguan,Guangdong 512029,China)

机构地区：[1]核工业二九〇研究所,广东韶关512029

出　　处：《世界核地质科学》2022年第2期223-231,共9页World Nuclear Geoscience

基　　金：中国核工业地质局项目“广东省诸广矿集区铀矿资源调查评价与勘查”(编号:201926);“广东省仁化县长江地区9号带南段深部铀矿普查”项目(编号:201926-2)联合资助。

摘　　要：坪下水地区位于粤北诸广岩体南部南雄断裂带,通过对区内辉绿岩脉开展岩相学和岩石地球化学研究,探讨了其成因,结果表明:区内辉绿岩具有低SiO_(2)(44.98%~50.87%)、低TiO_(2)(1.46%~1.94%)和低TFe_(2)O_(3)(10.63%~14.28%)特征,属于钙碱性玄武岩系列;微量元素相对富集Cs、Pb、U、W等元素,相对亏损Rb、Ba、Sb、Sr等元素,稀土元素总量较低(60.26×10^(-6)~141.48×10^(-6),平均96.58×10^(-6)),稀土元素配分曲线呈右倾型,未见明显Eu负异常。特征微量元素比值及图解显示其属于板内玄武岩,岩石物质组成具有洋中脊玄武岩(MORB)特征。综合分析认为,坪下水地区辉绿岩脉原始岩浆主要来源于富集型地幔,且在上升侵位过程中受到地壳混染的影响。Pingxiashui area is near the Nanxiong fault within the southern Zhuguang pluton in Northern Guangdong,China.In this paper,petrographic and petrogeochemical characteristics of the diabase dyke in Pingxiashui area were studied.The results showed that:diabase in Pingxiashui area is characterized by the low content of SiO_(2)(44.98%~50.87%),TiO_(2)(1.46%~1.94%)and TFe_(2)O_(3)(10.63%~14.28%),belong to calc-alkaline basalt series;Trace elements are relatively enriched in Cs,Pb,U,W,relatively loss of Rb,Ba,Sb,Sr,and low content ofΣREE(60.26×10^(-6)~141.48×10^(-6),average 96.58×10^(-6)).The REE pattern is right inclined,and no obvious negative Eu abnormality is found.The ratio of trace elements and the diagrams showed that it fall into intraplate basalt,and the rock material composition bears the characteristics of mid-ocean ridge basalt(MORB).Comprehensive analysis showed that the original magma of diabase dikes in the Pingxiashui area mainly came from enriched mantle and was affected by crustal contamination in the process of ascending emplacement.

关 键 词：辉绿岩 板内玄武岩 富集地幔 坪下水地区 

分 类 号：P619.14[天文地球—矿床学]