| 多门类化石在内蒙古白云鄂博群中的发现与宽沟群的建立 |
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| 引用本文： | 牛绍武,张鹏远,孙淑芬,刘永顺.多门类化石在内蒙古白云鄂博群中的发现与宽沟群的建立[J].地质通报,2016,35(11):1753-1770. |
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| 作者姓名： | 牛绍武 张鹏远 孙淑芬 刘永顺 |
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| 作者单位： | 中国地质调查局天津地质矿产研究所 |
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| 基金项目： | 中国地质调查局项目（编号：1212011085296） |
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| 摘 要： | 内蒙古白云鄂博地区具有世界上最大的稀有-稀土铁矿床,关于其时代归属尚存分歧。在都拉哈拉组(H3)与尖山组(H5)发现丰富的早寒武世微古植物化石,在尖山组(H5)硅质岩中发现早寒武世小壳化石,在哈拉霍疙特组(H8)确认了奥陶纪床板珊瑚的存在(包括块状群体与丛状群体),并首次发现大型古钵海绵化石与遗迹化石,在比鲁特组(H10)鲍玛序列中发现遗迹化石。初步确认,内蒙古商都地区三足化石(腕足类、头足类与腹足类)的层位可能为呼吉尔图组(或哈拉霍疙特组)。多门类化石的发现与确认,为重新认识白云鄂博超大型稀有-稀土铁矿床含矿地层时代提供了确凿的古生物化石证据,也为重新认识白云鄂博超大型稀有-稀土铁矿床的成矿地质背景开辟了新的研究思路,具有重要的地层学与大地构造学意义。根据多门类古生物化石组合与时代,将原白云鄂博群下部(H1~5)重新厘定为狭义的白云鄂博群,时代为早寒武世;原白云鄂博群上部(H6~15)重新命名为宽沟群,时代为早—中奥陶世,其间的假整合可能就是吉—黑地区的兴凯运动面。重新厘定的白云鄂博群与宽沟群一并划归天山-兴安地层区内蒙古草原地层分区,它是天山-兴安古生代海槽的一部分,并为海槽最南端的一个加里东褶皱带。
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| 关 键 词： | 白云鄂博群 宽沟群 早寒武世 早-中奥陶世 化石 |
| 收稿时间： | 2016/5/12 0:00:00 |
| 修稿时间： | 2016/8/20 0:00:00 |
The discovery of manifold kind fossils in the Bayan Obo Group in Inner Mongolia and the establishment of the Kuangou Group |
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| NIU Shaowu,ZHANG Pengyuan,SUN Shufen and LIU Yongshun.The discovery of manifold kind fossils in the Bayan Obo Group in Inner Mongolia and the establishment of the Kuangou Group[J].Geologcal Bulletin OF China,2016,35(11):1753-1770. |
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| Authors: | NIU Shaowu ZHANG Pengyuan SUN Shufen and LIU Yongshun |
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| Institution: | Tianjin Institute of Geology and Mineral Resources, China Geological Survey, Tianjin 300170, China |
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| Abstract: | There are the largest rare-earth ore deposit in the world and the extremely complicated earth crust structure in the Bayan Obo area. Through three years'' systematic investigation in the study area, the following progress has been made: the stratigraphic sequence of Bayan Obo Group is amended and reduced from 18 members to 15 members. They are as follows: Dulahala Formation (H1~3), Jianshan Formation (H4~5), Halahuogete Formation (h6~8), Bilute Formation (H9~10), Baiyinbulage Formation (H11~12), and Hujiertu Formation (H13~15). The Bayan Obo Group is unconformably underlain by the Lower Proterozoic metamorphosed rock-basement rocks, and in turn it is covered by Boligemiao Formation of upper Carboniferous Series. The microflora, predominated by Micrhystridium, Baltisphaeridium, are firstly discovered in the black slate and limestones of Dulahala Formation and Jianshan Formation. Their assemblage features may be correlated with the Lower Cambrian microflora found in Kunming region of Yunnan Province as well as with the fossil found in some regions in Europe. These microflora possesses obvious Early Cambrian character. Many species and genera of microanimal fossils have been firstly found in the siliceous rocks, intercalated with the black slate of Jianshan Formation. The well preserved subclass Tabulatomoepha fossils of species Lichenaria sp. and Rhabdotetradium sp. have been firstly collected from Halahuogete Formation (H8), together with Porifera Archaeocuphia sp. and trace fossils. The assemblage of Lichenaria-Rhabdotetradium-Archaeocyphia was found from Early-Middle Ordovician strata in North China Platform. Based on the palae-ontological animals and flora fossils, the Bayan Obo Group may be subdivided into two parts: Lower Cambrian and Lower-Middle Ordovician. The lower part of Bayan Obo Group is assigned to the narrow Bayan Obo Group (H1~5), and the upper part of Bayan Obo Group is named after the Kuangou Group (H6~15). So, the discovery of manifold kind fossils of the Bayan Obo Group in Inner Mongolia and the establishment of the Kuangou Group are of great significance for the study of the stratigraphy and geological structure in this region. |
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| Keywords: | Bayan Obo Group Kuangou Group Lower Cambrian Lower-Middle Ordovician fossils |
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