摘要
大兴安岭北段西部新巴尔虎右旗地区新厘定出非正式填图单元——上侏罗统哈日陶勒盖玄武岩,其岩石组合为灰黑色、深绿灰色、紫褐色玄武岩以及气孔杏仁状玄武岩、碱性橄榄玄武岩、玄武粗安岩等。锆石SHRIMP U-Pb定年法测得其年龄数据为(146.7±3.1)Ma,时代为晚侏罗世。岩石地球化学分析显示,哈日陶勒盖玄武岩属高钾钙碱性系列,岩石中Sr含量低,富集大离子亲石元素Rb、K、Ba,亏损高场强元素Nb、Ti,稀土元素含量总体较高,轻重稀土分馏明显,略具有铕负异常。上侏罗统哈日陶勒盖玄武岩的厘定说明,大兴安岭地区存在晚侏罗世基性火山岩浆活动事件。通过区域地质调查和地层对比,上侏罗统哈日陶勒盖玄武岩与上侏罗统伊列克得组原始定义相符,二者实则为同物异名,建议恢复上侏罗统伊列克得组。这一认识对大兴安岭中生代构造岩浆活动的研究及中生代火山岩地层划分对比具有重要地质意义。
The Upper Jurassic basaltic rocks of the Haritaolegai Formation were firstly identified in the western part of the northern Da Hinggan Mountains,with the rock assemblage including black/dark gray/purplish brown basalt,amygdaloid basalt,alkaline olivine basalt and basaltic trachy and esite. SHRIMP zircon U-Pb dating of the basalt yielded Late Jurassic age of（ 146. 7 ± 3. 1） Ma. Lithogeochemical data show that the rocks are highK calc-alkaline. The basalts contain low content of Sr,and show enrichments in high large ion lithophile elements（ LILEs,such as Rb,K and Ba） and depletions in high field strength elements（ HFSEs,such as Nb and Ti）. The rare-earth element（ REE） contents are generally high,yet the REE fractionation is unclear and the rocks contain slightly negative Eu anomalies. Based on the regional geological survey and strata contrast,theUpper Jurassic Haritaolegai Formation basalt is confirmed to fit the definition of the ever used Yiliekede Formation,so they are the same petrographic composition. Therefore,this study suggests that the Yiliekede Formation should be resumed,and the confirmation of this formation is of great geological significance for the study of tectonic-magmatic activities in the Mesozoic and the comparison of Mesozoic volcanic strata in the study area.
作者
赵胜金
高利东
于海洋
朴丽丽
柳志辉
周颖帅
张猛
张玉龙
杨海星
赵万莉
ZHAO Shengjin;GAO Lidong;YU Haiyang;PIAO Lili;LIU Zhihui;ZHOU Yingshuai;ZHANG Meng;ZHANG Yulong;YANG Haixing;ZHAO Wanli(School of Earth Sciences and Resources,China University of Geosciences;No.10 Institute of Geological Exploration,Inner Mongolia Bureau of Geology and Mineral Resources,Chifeng,Inner Mongolia 024005,China)
出处
《现代地质》
CAS
CSCD
北大核心
2018年第4期718-726,共9页
Geoscience
基金
中国地质调查局工作项目(12120114086201
DD20160047
DD20160048-11)
关键词
哈日陶勒盖玄武岩
上侏罗统
U-PB测年
岩石地球化学特征
大兴安岭北段
basalt in the Hartaolegai Fomation
Upper Jurassic
U-Pb datic
lithogeochemical characteristic
north Da Hinggan Mountains
