内蒙古滴水沟闪长岩体地球化学特征及其地质意义  

Geochemical Characteristics of Dishuigou Diorite in Inner Mongolia and Its Geological Significance

作　　者：胡鸿飞[1,2] 张永全[3] 胡华斌[4] 张超[1] 张利忠 

机构地区：[1]中国地质大学(北京)地质过程与矿产资源国家重点实验室,北京100083 [2]中国人民武装警察部队黄金第二支队,内蒙古呼和浩特010010 [3]中国石油大学胜利学院,山东东营257097 [4]石家庄经济学院资源学院,河北石家庄050031 [5]内蒙古第五地质矿产勘查开发院,内蒙古包头014010

出　　处：《现代地质》2013年第6期1308-1315,共8页Geoscience

基　　金：国家重点基础研究发展计划项目(2009CB421008);国家自然科学基金项目(41021091);国土资源部地质大调查项目(1212011220492)

摘　　要：滴水沟闪长岩体位于华北板块北缘西段狼山构造带。结合前人的锆石 U-Pb 测年资料，可确定其形成于晚石炭世-早二叠世早期。岩石学及地球化学分析显示岩体属钙碱性系列，相对富集 Rb、Ba、Th、K、P 等大离子亲石元素，亏损 Nb、Ta、Ti 等高场强元素，具有低 Rb /Sr（0.05～0.10）值、高 Ba/Rb（11.45～22.16）值，且 A /CNK ＜1.1；REE 含量显示，滴水沟闪长岩体为轻稀土富集型，轻、重稀土元素高度分异，轻稀土元素发生明显的分馏作用，铕异常不明显（δEu ＝0.92～1.13），反映了俯冲带岩浆岩的特征，推测其物质来源为幔壳混源型。结合区域构造演化，认为其形成于活动板块边缘（碰撞前）火山弧环境，与晚石炭世晚期古亚洲洋板块向华北板块北缘西段的俯冲有关。The Dishuigou dioritic intrusion is located in the Langshan arc at the northern margin of the North China Craton （NCC）,Inner Mongolia.It is emplaced in the Late Carboniferous-Early Permian according to the previous zircon U-Pb dating data.In this paper,the major and trace （including rare earth）elements composi-tion of the Dishuigou diorite are reported.The result shows relatively enriched in large ion lithophile elements （LILE）such as the Rb,Ba,Th,K,and P,and depleted in high field strength elements （HFSE）such as the Nb,Ta,and Ti,and high Rb /Sr （0.05 -0.10）and Ba /Rb （11.45 -22.16）values,and low A /CNK （〈1.1）.In combination with the strong fractionation REE （LREE /HREE =2.97 -3.31）and LREE （La /Sm=2.75 -3.57）,and insignificant Eu anomalies （δEu =0.92 -1.13）,suggesting the dioritic intrusion formed in an arc environment and derived from mantle melt mixed with crust material during ascending.It is concluded that the southward subduction of the paleo-Asian oceanic slab in Late Carboniferous-Early Permian resulted in the formation of the Dishuigou dioritic intrusion based on the regional evolution the Langshan arc.

关 键 词：闪长岩 地球化学特征 滴水沟岩体 内蒙古 

分 类 号：P588.122[天文地球—岩石学]