| 安徽南部下、中奥陶统紫台组碳酸盐岩微相与海平面变化 |
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| 引用本文： | 栾晓聪,刘建波,詹仁斌,吴荣昌.安徽南部下、中奥陶统紫台组碳酸盐岩微相与海平面变化[J].古地理学报,2015,17(2):249-264. |
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| 作者姓名： | 栾晓聪 刘建波 詹仁斌 吴荣昌 |
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| 作者单位： | 1.现代古生物学和地层学国家重点实验室,中国科学院南京地质古生物研究所,江苏南京 210008;2.中国科学院大学,北京 100049;3.北京大学地球与空间科学学院,北京 100871 |
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| 基金项目： | 国家基金委创新研究群体项目(编号:41221001)、重大项目(编号:41290260)及面上项目(编号:41272035,41202005)共同资助 |
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| 摘 要： | 下、中奥陶统紫台组形成于华南奥陶纪生物大辐射的关键时期,其中蕴藏了一些与大辐射有关的重要信息。笔者通过对安徽南部石台丁香剖面、池州洪家剖面的紫台组进行野外实测、采样、室内切片和镜下观察与分析,共识别出9个碳酸盐岩微相,即:MF-1钙质泥岩、MF-2泥质泥晶灰岩、MF-3泥晶灰岩、MF-4腹足类—介形虫生屑泥晶灰岩、MF-5海绵骨针含生屑泥晶灰岩、MF-6含生屑泥质泥晶灰岩、MF-7生屑泥质泥晶灰岩、MF-8生屑泥晶灰岩和MF-9泥晶生屑灰岩。这些微相主要形成于深潮下带及相邻环境中。研究表明:皖南紫台组沉积时期水深波动幅度不大,且自早至晚沉积水深逐渐加大;丁香剖面由于更接近台地边缘,总体沉积水深要大于洪家剖面。在2条剖面的紫台组中识别出至少5次比较显著的海平面上升事件,它们与上扬子区海侵事件具有良好的对应关系,并可以与澳大利亚、北欧、北美、华北等板块进行对比。由此推断,区域性相对海平面变化、甚至全球性海平面变化控制着下扬子区下、中奥陶统紫台组的沉积及其变化。
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| 关 键 词： | 紫台组 微相 海平面变化 奥陶纪 安徽 |
| 收稿时间： | 2014-11-24 |
Microfacies of carbonate rocks and sea-level changes in the Lower to Middle Ordovician Zitai Formation of southern Anhui Province |
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| Luan Xiaocong,Liu Jianbo,Zhan Renbin,Wu Rongchang.Microfacies of carbonate rocks and sea-level changes in the Lower to Middle Ordovician Zitai Formation of southern Anhui Province[J].Journal of Palaeogeography,2015,17(2):249-264. |
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| Authors: | Luan Xiaocong Liu Jianbo Zhan Renbin Wu Rongchang |
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| Institution: | 1.State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,;Chinese Academy of Sciences,Nanjing 210008,Jiangsu;2.University of Chinese Academy of Sciences,Beijing 100049;3.School of Earth and Space Sciences,Peking University,Beijing 100871 |
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| Abstract: | The Lower to Middle Ordovician Zitai Formation,a unique lithologic unit formed during the critical period of the Great Ordovician Biodiversification Event(GOBE),contains some important information about this major biotic event. Based on detailed investigation and sampling in the field and observation under the microscope in the lab,nine carbonate microfacies were distinguished in the Zitai Formation at Dingxiang section of Shitai County and Hongjia section of Chizhou County,southern Anhui Province,East China,named as the MF-1 calcareous shale,the MF-2 argillaceous mudstone,the MF-3 mudstone,the MF-4 gastropod-ostracod wackestone,the MF-5 calthrop-bearing wackestone,the MF-6 argillaceous bioclast-bearing wackestone,the MF-7 argillaceous bioclastic wackestone,the MF-8 bioclastic wackestone and the MF-9 bioclastic packstone. These microfacies were deposited in deep subtidal and adjacent zones with low amplitude of changes in water depths. Taking into account of some other evidences that we observed in the field,we proposed that depositional environment of the Zitai Formation at Dingxiang section was deeper than that at Hongjia section. Five transgressive events in the Zitai Formation were recognized at both sections. All these transgressions can be precisely correlated between the studied sections and the sections on the Yangtze Platform,as well as on some other palaeoplates. Thus the changes in deposition of the Zitai Formation in the Lower Yangtze region were controlled by regional and even global eustatic sea-level fluctuations. |
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| Keywords: | Zitai Formation microfacies sea-level change Ordovician Anhui Province |
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