内蒙古中部毫义哈达岩体的年代学和地球化学特征  

Geochemical characteristics and zircon U-Pb dating of the Haoyihada intrusive body in the middle region of Inner Mongolia

作　　者：苏捷[1] 张宝林[1] 徐永生[1] 祁民[1] 沈晓丽[1] 郭志华[1] 

机构地区：[1]中国科学院地质与地球物理研究所矿产资源研究重点实验室,北京100029

出　　处：《地质科学》2010年第2期564-579,共16页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家重点基础研究规划"973"项目二级课题(编号:2006CB403507);国家"十一五"科技支撑计划重大项目二级课题(编号:2006BAB01A02)联合资助的成果

摘　　要：内蒙古中部毫义哈达岩体位于华北板块北缘陆缘增生带,通过对该岩体进行系统的年代学与地球化学研究表明,毫义哈达岩体是由辉石闪长岩类构成。在对两个样品中的锆石进行LA-ICP-MS U-Pb定年,结果(加权平均年龄)均为266±2 Ma,表明岩体的形成时代为晚二叠世。对14个样品进行主量元素和微量元素分析,表明岩体属钙—碱性系列;Eu有一定程度的负异常,富集大离子亲石元素Rb、Sr及轻稀土,亏损高场强元素Nb、Ta,富Cu、Cr等过渡元素。岩体在地球化学上还具有岛弧火山岩的特征,推测其岩浆源区曾遭受过古亚洲洋板片流体交代。依据区域构造演化,推测毫义哈达岩体侵位于造山后伸展环境,成岩物质来源于上地幔并且发生了结晶分离作用。地球化学的特征以及在该岩体发现的铜钨矿化,预示着该地区将是一个有利的成矿远景区。The Haoyihada intrusive body,which occurred in the continental margin accretion belt along the north margin of North China Plate in the middle region of Inner Mongolia,is composed the pyroxene diorite. With isotopic dating and geochemical research,the zircon LA-ICP-MS U-Pb dating of two samples yields an age of 266±2 Ma,failing into the range of late Permian Epoch. The geochemical characteristics of 14 samples are as follows,the pyroxene diorite shows low-SiO_2（47.87～56.17 wt%）,high-Mg（3.65～6.79 wt%）,also higher large-ion lithophile element of Rb,Sr and LREE,low high-field strength elements of Nb,Ta,high-Cu（35.97×10^（-6）～112.24×10^（-6））,REE patterns have negative Eu anomalies. It is suggested that the Haoyihada intrusive body should be among the calc-alkaline series,has the tectonic background of island-arc and its materials mainly derived from upper mantle and had fractional crystallization. The geochemical characteristics and the strong mineralization of Cu and W of Haoyihada intrusive body prefigured that the potential of ore prospecting and exploration is great in this area.

关 键 词：毫义哈达岩体 辉石闪长岩 锆石U-PB定年 地球化学 

分 类 号：P588[天文地球—岩石学] P597[天文地球—地质学]