华北陆块南缘张士英岩体岩石地球化学特征及地质意义  

Petrogeochemical characteristics and geological genesis of Zhangshiying rock mass in southern margin of North China block

作　　者：姜玉平 张森森 JIANG Yuping;ZHANG Sensen(Henan Nonferrous Mineral Exploration Engineering Research Center,Zhengzhou 450000,Henan,China;2 No.6 Geological Team of Henan Province Nonferrous Metals Geological Mineral Resources Bureau,Zhengzhou 450000,Henan,China;Henan General Institute of Non-ferrous Metals Geological Exploration,Zhengzhou 450000,Henan,China)

机构地区：[1]河南省有色金属矿产探测工程技术研究中心,河南郑州450000 [2]河南省有色金属地质矿产局第六地质大队,河南郑州450000 [3]河南省有色金属地质勘查总院,河南郑州450000

出　　处：《河南理工大学学报（自然科学版）》2020年第4期45-53,共9页Journal of Henan Polytechnic University（Natural Science）

基　　金：河南省国土资源科研项目(豫国土资函〔2017〕237号-02)。

摘　　要：通过研究张士英岩体的地球化学特征,探讨其岩体成因及地质意义。主量元素研究表明,花岗斑岩、角闪石英正长岩及暗色包体均表现出碱性岩特征。微量元素显示,张士英岩体内的角闪石英正长岩和暗色包体具有相似稀土元素配分模式曲线,轻稀土富集,曲线总体右倾;两者都有着较高的稀土总量,前者稀土总量平均值319.28×10^-6,δEu=0.24~0.25;后者稀土总量略高,平均值357.00×10^-6,δEu=0.24~0.31;张士英岩体内的花岗斑岩稀土总量平均值156.63×10^-6,δEu=0.12~0.19。3类岩石都表现出Eu的负异常和Ce的正异常。角闪石英正长岩与暗色包体的微量元素蛛网图相似,均富集Rb,Th等大离子亲石元素,亏损Nb,Ta等高场强元素,暗示成岩以幔源物质为主。花岗斑岩有着较低的w(Nb)/w(Ta),其形成过程中可能有壳源物质加入。综合认为,张士英岩体形成于构造体制由挤压向伸展转折以及之后的岩石圈大规模的伸展、减薄期间,是一种具有壳源特征的花岗岩体。Based on the study of geochemical characteristics of Zhangshiying rock mass,the genesis and geological significance of the rock mass were discussed.Studies of principal elements presented that granite porphyry,hornblende quartz syenite and dark inclusions all showed the characteristics of alkaline rocks;trace elements feature showed that the hornblende syenite and dark inclusions in Zhangshiying rock mass had similar distribution pattern curves of rare earth elements,and had high amounts of rare earths,and the curve generally inclined to the right.Both of them had higher total amount of rare earth,the average value of the former was 319.28×10^-6,δEu=0.24~0.25,and that of the latter was 357.00×10^-6,δEu=0.24~0.31,the average value of total amount of rare earths of granite porphyry in Zhangshiying rock mass was 156.63×10^-6,δEu=0.12~0.19.The three types of rocks showed negative anomaly of Eu and positive anomaly of Ce.The trace elements cobweb map of hornblende quartz syenite was similar to that of dark inclusions,which was rich in Rb,Th and other large ion lithophile elements,deficient in Nb,Ta and other high field strength elements,suggesting that the diagenesis was dominated by mantle source material.Granite porphyry has a low w(Nb)/w(Ta)ratio,and the formation process may have the addition of shell source material.To sum up,the Zhangshiying rock mass is a kind of shell-source granite porphyry,which was formed during the transition of tectonic system to the extension,and the subsequent large-scale extension and thinning of the lithosphere.

关 键 词：华北陆块南缘 地球化学特征 微量元素特征 张士英岩体 

分 类 号：P591[天文地球—地球化学] P581[天文地球—地质学]