| 张庆礼,杨开国,张洋,石宗户,刘洋,冶北北.内蒙古东乌旗西南部格根敖包组地层划分及其同位素年代学初步研究[J].矿产勘查,2023,14(7):1034-1042 |
| 内蒙古东乌旗西南部格根敖包组地层划分及其同位素年代学初步研究 |
| Stratigraphic subdivision and isotope geochronology study on the Gegen Obo Formation in the southwestern of Dongwu Banner， Inner Mongolia |
| 投稿时间：2023-03-11 修订日期：2023-06-10 |
| DOI：10.20008/j.kckc.202307004 |
| 中文关键词: 东乌旗 格根敖包组 LA-MC-ICP年龄 晚石炭世—早二叠世 锆石U-Pb测年 |
| 英文关键词: Dongwu Banner Gegenaobao Formation LA-MC-ICP Late Carboniferous-Early Permian Ziroon U-Pb dating |
| 基金项目:本文受内蒙古地勘基金项目（NMKD-2013-05）资助。 |
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| 中文摘要: |
| 内蒙古东乌旗西南部的格根敖包组由于露头出露有限，接触关系不清，化石较少，长期以来是本区地层工作的难点，由于受到贺根山蛇绿混杂岩破坏以及新生代沉积物的覆盖，格根敖包组地层的划分与对比、地层的时代等一直比较混乱。本文按照岩性组合差异将格根敖包组划分为以中酸性火山碎屑岩夹火山熔岩及少量的正常碎屑沉积岩的第一岩性段；以正常碎屑沉积岩为主夹少量的中酸性火山碎屑岩的第二岩性段；以正常沉积碎屑岩夹生物碎屑灰岩透镜体的第三岩性段。在第一岩性段英安岩中采取同位素样品，挑选锆石进行U-Pb同位素测年，获得了（310.5±2.9）Ma的年龄信息；在第三岩性段中采集腕足类动物化石、海百合茎植物化石，经鉴定其时代为石炭纪—二叠纪，最终将格根敖包组地层时代定为晚石炭世—早二叠世。 |
| 英文摘要: |
| The Gegenaobao Formation in the southwest of Dongwu Banner， Inner Mongolia， has long been a difficulty in stratigraphic work in this area due to limited outoutings， unclear contact relations and few fossils. Due to the destruction of Hegenshan ophiolitic melange and the coverage of Cenozoic sediments， the stratigraphic division， correlation and stratigraphic age of Gegenaobao Formation have been confused. According to the difference of lithology combination， the Gegenaobao Formation is divided into the first lithology segment， which consists of medium-acid pyroclastic rocks mixed with volcanic lava and a small amount of normal clastic sedimentary rocks. The second lithologic segment is dominated by normal clastic sedimentary rocks with a small amount of medium-acid pyroclastic rocks. The third lithologic segment of bioclastic lens is composed of normal sedimentary clastic rocks. Zircon was selected from the dacite of the first lithology group for U-Pb isotopic dating， and the age information of （310.5±2.9） Ma was obtained. Brachiopod fossils and crinoid stem plant fossils were collected from the third lithology section， and the stratigraphic age of Gegenaobo Formation was determined to be Late Carboniferous to Early Permian. |
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