内蒙古四子王旗地区小南山辉长岩LA-ICP-MS锆石U-Pb年龄及其地质意义  

LA-ICP-MS zircon U-Pb dating of the gabbro from Xiaonanshan,Siziwang Banner,Inner Mongolia,and its geological significance

作　　者：党智财 李俊建[1] 赵泽霖[1,2] 付超[1] 唐文龙[1] 

机构地区：[1]中国地质调查局天津地质矿产研究所,天津300170 [2]中国地质科学院研究生部,北京100037

出　　处：《地质通报》2016年第4期583-592,共10页Geological Bulletin of China

基　　金：中国地质调查局项目(编号:1212010561510;1212010811061;1212011120330;12120114001201;1212010781028;1212011085488);国土资源公益性行业科研专项(编号:200811010);国家国际科技合作项目(编号:2012DFB20220)

摘　　要：四子王旗地区小南山为内蒙古中部镁铁质-超镁铁质岩带内发育的一个中型铜镍铂硫化物矿床,辉长岩为含矿岩体的成矿母岩。岩石主量、微量及稀土元素分析结果表明,小南山辉长岩属于铁质镁铁质岩,具有拉斑玄武岩系列演化趋势,相对富集大离子亲石元素(Rb、Ba、U、Pb等)和亏损高场强元素(Nb、Ta、Ti),并具有轻、重稀土元素分馏相对明显、轻稀土元素相对富集、重稀土元素亏损的右倾型稀土元素配分模式。采用LA-ICP-MS锆石U-Pb测年法,获得小南山辉长岩年龄结果为272.7±2.9Ma,代表了小南山辉长岩体的成岩成矿时代,属中二叠世。区域地质资料及微量元素特征表明,小南山岩体可能形成于板内构造环境。Located on the northwestern margin of the North China Craton,Siziwang Banner belongs tectonically to Bayun Obo marginal rift. It is about 100 km away from the north of Solonker suture. A mafic-ultramafic belt is exposed in central Inner Mongolia,in EW extension roughly 300 km long and 30 km wide,comprising a favorable metallogenic belt for Cu-Ni（PGE） sulfide deposits.Many Cu-Ni（PGE） deposits（ore spots） have been found here including the Xiaonanshan Cu-Ni（PGE） deposit. The Xiaonanshan intrusion consists of gabbro and belongs to the tholetiitic series in petrochemical composition. Most of the rocks are relatively enriched in large ion lithophile elements（Rb,Ba,U,Pb） and depleted in high field strength elements（Nb,Ta,Ti）,exhibiting right-inclined linear REE patterns with LREE enrichment relative to HREE. LA-ICP-MS U-Pb dating of zircons from Xiaonanshan orebearing gabbro yielded an age of 272.7±2.9Ma,indicating that the pluton should be the Mid-Permain intrusion. According to the regional geology,combined with the geochemical features,it may be inferred that the intrusion may be associated with intraplate tectonic setting.

关 键 词：四子王旗 小南山辉长岩 中二叠世 板内 LA-ICP-MS锆石U-PB年龄 

分 类 号：P588.124[天文地球—岩石学] P597.3[天文地球—地质学]