内蒙古北山地区黑红山一带斑状花岗闪长岩地球化学特征、LA-ICP-MS锆石U-Pb年龄及其地质意义  

Geochemical characteristics and LA-ICP-MS zircon U-Pb age of porphyritic granodiorite in Heihongshan area of Beishan region, Inner Mongolia, and their geological significance

作　　者：程海峰 辛后田 梁国庆 张正平 张永 冯翼鹏 朱炜 提振海 苏朋涛 CHENG Haifeng;XIN Houtian;LIANG Guoqing;ZHANG Zhengping;ZHANG Yong;FENG Yipeng;ZHU Wei;TI Zhenhai;SU Pengtao(The Institute of Regional Geological Survey of Hebei Province,Langfang 065000,Hebei,China;Tianjin Geological Survey,Tianjin 300170,China)

机构地区：[1]河北省区域地质调查院,河北廊坊065000 [2]中国地质调查局天津地质调查中心,天津300170

出　　处：《地质通报》2018年第10期1895-1904,共10页Geological Bulletin of China

基　　金：中国地质调查局项目<阴山成矿带小狐狸山和雅布赖地区地质矿产调查:内蒙古1:5万黑红山等三幅区域地质矿产调查>(编号:DD20160039)

摘　　要：北山地区黑红山一带出露的晚石炭世斑状花岗闪长岩大地构造位置位于北山-天山造山系、额济纳-北山弧盆系,至今未见可靠的同位素年龄报道。在运用阴极发光技术对岩石中的锆石进行内部结构分析的基础上,利用LA-ICP-MS锆石UPb同位素原位定年方法获得206Pb/238U年龄加权平均值为312.1±3.2Ma。岩石化学研究显示,斑状花岗闪长岩属中钾钙碱性、准铝质-弱过铝质系列,具I型花岗岩特征;轻稀土元素富集,轻、重稀土元素分馏明显,稀土元素配分曲线右倾;微量元素不同程度地富集Rb、Th、K、Hf,亏损Ta、Nb、Ti、P等元素,显示其形成于板块碰撞前的火山弧环境。结合区域地质背景分析,红石山-百合山-蓬勃山蛇绿岩带代表的洋盆在晚石炭世尚未消亡。The tectonic location of Late Carboniferous porphyritic granodiorite of Heihongshan area in Beishan region belongs to Beishan-Tianshan orogenic system and Ejina-Beishan arc basin system,but without reliable zircon U-Pb dating report.On the basis of the detailed internal structure analysis of zircons from the porphyritic granodiorite using the technology of cathodoluminescence,the authors conducted isotope age analysis using LA-ICP-MS zircon U-Pb dating method.The result shows that porphyritic grano-diorite formed at 312.1±3.2Ma.Geochemical study shows that porphyritic granodiorite belongs to medium potash-calc alkaline,qua-si-aluminous granite system,being I type granite.It has characteristics of light REE enrichment and characteristics of enrichment of Rb,Th,K,Hf and depletion of Ta,Nb,Ti,P.It formed in a pre-collision tectonic environment.Combined with regional geologi-cal background,It is considered that ocean basin,represented by Hongshishan-Baiheshan-Pengboshanophiolite,should not have been closed in Late Carboniferous period.

关 键 词：北山地区 斑状花岗闪长岩 锆石U-PB年龄 地球化学 

分 类 号：P588.12[天文地球—岩石学] P597.3[天文地球—地质学]