| 重庆秀山小茶园锰矿南华系大塘坡组古环境* |
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| 引用本文： | 马志鑫,罗亮,刘喜停,刘伟,孙志明.重庆秀山小茶园锰矿南华系大塘坡组古环境*[J].古地理学报,2016,18(3):473-486. |
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| 作者姓名： | 马志鑫 罗亮 刘喜停 刘伟 孙志明 |
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| 作者单位： | 1.中国地质调查局成都地质调查中心,四川成都 610081;2.中国科学院海洋研究所海洋地质与环境重点实验室,山东青岛 266071 |
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| 基金项目： | *国土资源部公益性行业科研专项(编号:201411051)、中国地质调查局地质调查项目(编号:12120113050300,12120114016201)联合资助 |
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| 摘 要： | 认识渝湘黔地区南华系的沉积构造背景可以为该地区锰矿勘探提供新的依据,基于此,文中对重庆秀山小茶园锰矿ZK0606钻孔的南华系千子门组和大塘坡组开展了系统的沉积环境和地球化学分析。沉积相分析结果表明,该套地层共可划分出冰水浅海、局限边缘盆地和浅水陆棚3种沉积环境。地球化学分析结果表明,研究区大塘坡组稀土元素总量较高、富轻稀土元素、具Eu负异常,结合Al2O3/(Al2O3+Fe2O3)、Al/(Al+Fe+Mn)值等,推测其形成于被动大陆边缘背景。根据微量元素含量及其比值(U、V、Mo、V/Cr)等推测,大塘坡组一段沉积于缺氧—贫氧沉积环境,而大塘坡组二段逐渐过渡到氧化沉积环境;根据Al/Ca值、化学蚀变指数(CIA)等指标分析,该套地层自下而上化学风化强度逐渐增大、陆源碎屑供给增多,这可能与Sturtian冰期结束、气候变暖和海平面迅速升高有关。综合上述分析结果认为,重庆秀山小茶园锰矿主要产出于大塘坡组一段下部相对深水厌氧的局限边缘盆地环境中。
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| 关 键 词： | 南华系 地球化学 沉积环境 重庆 |
| 收稿时间： | 06 May 2015 |
Palaeoenvironment of the Datangpo Formation of Nanhua System in Xiaochayuan Manganese Deposit in Xiushan area of Chongqing |
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| Ma Zhixin,Luo Liang,Liu Xiting,Liu Wei,Sun Zhiming.Palaeoenvironment of the Datangpo Formation of Nanhua System in Xiaochayuan Manganese Deposit in Xiushan area of Chongqing[J].Journal of Palaeogeography,2016,18(3):473-486. |
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| Authors: | Ma Zhixin Luo Liang Liu Xiting Liu Wei Sun Zhiming |
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| Institution: | 1.Chengdu Center,China Geological Survey,Chengdu 610081,Sichuan;2.Key Laboratory of Marine Geology and Environment, Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,Shandong |
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| Abstract: | In order to provide a new understanding of sedimentary tectonic setting of the Nanhua system for manganese ore exploration in Chongqing-Hubei-Hunan area,we carried out sedimentological and geochemical analyses of the Qianzimen and Datangpo Formations of Nanhua System from Core ZK0606 at Xiaochayuan Manganese Deposit in Xiushan area of Chongqing. Based on the sedimentological analysis results,three kinds of sedimentary facies were distinguished,including shallow glacial marine,limited marginal basin and shallow shelf. The geochemical analysis data of higher total REE,LREE-rich,with a negative Eu anomaly,ratios of Al2O3/(Al2O3+Fe2O3)and Al/(Al+Fe+Mn)reflect that the Datangpo Formation deposited in a passive continental margin. The trace element content and ratios(U,V,Mo,V/Cr)show that the Member 1 of Datangpo Formation formed in the anoxic environment,with a gradual transition to oxic environments in the Member 2 of Datangpo Formation. The Al/Ca ratios and the chemical index of alteration(CIA)indicate that the chemical weathering and terrigenous supply were gradually increased from bottom to top, correspondind to the end of Sturtian glaciation,global warming and sea level rise. Based on the above analyses,it is indicated that the Manganese ore mainly formed in limited marginal basin with relatively deep water and anoxic conditions during the depositional period of lower section of the Member 1 of Datangpo Formation. |
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| Keywords: | Nanhua System geochemistry sedimentary environment Chongqing |
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