地质与勘探2017，Vol.53Issue(6)：1129-1139,11.
内蒙古北山地区北山岩群斜长角闪岩LA-ICP-MS锆石U-Pb定年及其地质意义
LA-ICP-MS Zircon U-Pb Dating of Amphibolites of the Beishan Group in the Beishan Area, Inner Mongolia and its Geological Significance
摘要
Abstract
The exposure of Beishan group in the Biaoshan area of Beishan, Inner Mongolia is relatively complete. According to the regional geology, petrological and geochemical characteristics, amphibolites from the Beishan group were separated in this work, with protolith of basic dykes of gabbro and diabase. We used LA-ICP-MS method to conduct zircon U-Pb isotopic dating on the amphibolites to obtain weighted average age of 1623 ± 21 Ma and the apparent 207 Pb/ 206 Pb ages of 1547~1691 Ma. The zircons are mostly hypautomorphic dipyramidal-prismatic crystals, with grain size of 0. 03 ~0. 21 mm and showing oscillatory zoning, and obvious core-mantle-rim textures. The Th/U ratios are 0. 38 ~0. 92 obtained from 30 zircon analysis points, and mostly are >0. 4. The above features indicate that zircons are of a magmatic origin, not a metamorphic origin. Therefore, the isotope age of zircons is the crystallization age of amphibolites, indicating that the diagenetic age of Beishan group is earlier than 1623 ± 21 Ma. Comprehensive research shows that the amphibolite was formed in the Paleoproterozoic extensional continental environment. This result has important significance for the research of the age of Beishan group and the tectonic evolution history of the Beishan area.关键词
北山岩群/斜长角闪岩/LA-ICP-MS锆石U-Pb定年/古元古代/北山地区/内蒙古Key words
Beishan group/amphibolite/LA-ICP-MS zircon U-Pb dating/Paleoproterozoic/Beishan area/Inner Mongolia分类
天文与地球科学引用本文复制引用
张正平,段炳鑫,孟庆涛,徐翠,董洪凯,刘广,提振海..内蒙古北山地区北山岩群斜长角闪岩LA-ICP-MS锆石U-Pb定年及其地质意义[J].地质与勘探,2017,53(6):1129-1139,11.基金项目
中国地质调查局大兴安岭成矿带南段地质矿产调查项目《内蒙古1:5万标山、咸味井、骨头井、化石山幅区域地质矿产调查》(编号:12120113056000)资助. （编号:12120113056000）
