| 冀东秦家峪中元古界高于庄组锰矿成因:来自矿物学和地球化学的制约 |
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| 引用本文： | 靳松,马鹏飞,郭华,余文超,许灵通,林茜.冀东秦家峪中元古界高于庄组锰矿成因:来自矿物学和地球化学的制约[J].地球科学,2022,47(1):277-289. |
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| 作者姓名： | 靳松 马鹏飞 郭华 余文超 许灵通 林茜 |
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| 作者单位： | 1.河北省地质矿产勘查开发局博士后科研工作站, 河北石家庄 050081 |
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| 基金项目： | 国家自然科学基金项目(No.41402091);河北省地矿局博士后科研工作站项目(No.454-0602-YBN-Z9E4);河北省高层次人才工程培养经费资助项目(Nos.B2020005007,A2016002031);河北省自然科学基金项目(No.D2021334001)。 |
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| 摘 要： | 冀东秦家峪锰矿赋存于中元古界蓟县系高于庄组二段底部含锰岩系内，其成因尚不明确. 以秦家峪锰矿ZK58-2钻孔样品为研究对象，通过显微薄片观察、电子探针分析及全岩地球化学分析等方法，探讨了高于庄组锰矿的锰质来源和沉积环境对成矿的贡献. 显微薄片观察、电子探针分析表明，原生矿带中含锰矿物主要为菱锰矿、铁镁菱锰矿、钙菱锰矿、锰方解石等含锰碳酸盐矿物. 主量元素分析显示，相对于底板样品，锰矿层样品(Mn>8%)的TiO2、SiO2、Al2O3、K2O、Na2O含量较低，Mn含量与Al2O3呈负相关. 锰矿层样品和底板样品微量元素相对于上地壳(UCC)未表现出特别富集的特征，富集系数显示仅Th、U轻微富集. Th/U及自生Th/U比值具有相似的地层变化趋势，与较低的Fe/Mn比值共同指示沉积水体以次氧化环境为主. UCC标准化的稀土元素配分曲线较为平坦，不存在显著的Ce异常(Ce/Ce*=1.00±0.02，n=39)，具有较低的Y/Ho比值. 初始87Sr/86Sr比值介于0.713 383~0.725 378之间，平均值为0.720 180，与Al2O3含量呈负相关. 秦家峪锰矿矿物学及地球化学特征表明，高于庄组含锰岩系的锰质来源于热液与陆源风化双重输入，其与裂谷盆地演化、古海洋氧化以及海平面变化等多种因素共同制约着高于庄组锰矿的形成.
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| 关 键 词： | 秦家峪 高于庄组 锰矿 古环境 地球化学 |
| 收稿时间： | 2021-04-26 |
Genesis of Mesoproterozoic Gaoyuzhuang Formation Manganese Ore in Qinjiayu,East Hebei:Constraints from Mineralogical and Geochemical Evidences |
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| Jin Song,Ma Pengfei,Guo Hua,Yu Wenchao,Xu Lingtong,Lin Qian.Genesis of Mesoproterozoic Gaoyuzhuang Formation Manganese Ore in Qinjiayu,East Hebei:Constraints from Mineralogical and Geochemical Evidences[J].Earth Science-Journal of China University of Geosciences,2022,47(1):277-289. |
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| Authors: | Jin Song Ma Pengfei Guo Hua Yu Wenchao Xu Lingtong Lin Qian |
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| Affiliation: | (Post-Doctoral Scientific Research Workstation,Hebei Bureau of Geology and Mineral Resources Exploration,Shijiazhuang 050081,China;State Key Laboratory of Biogeology and Environmental Geology,School of Earth Sciences,China University of Geosciences,Wuhan 430074,China;Hebei Institute of Geological Survey,Shijiazhuang 050081,China) |
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| Abstract: | The Qinjiayu manganese ore in East Hebei occur mainly in manganese-bearing rock series at the bottom of the second member of the Mesoproterozoic Gaoyuzhuang Formation,however,the cause of manganese ore is unclear.In this paper,it uses microscopic observation,electronic microprobe analysis and whole rock geochemical analysis based on the drilling core ZK58-2 samples to provide information on the manganese sources and sedimentary environments which contribute to manganese mineralization.Microscopic examination and electronic microprobe analysis show that manganese-bearing minerals of primary ore belt samples are dominated by rhodochrosite,Fe-Mg rhodochrosite,Ca rhodochrosite and Mn calcite.Compared with based samples,the major elements of the manganese ore belt samples show low TiO2,SiO2,Al2O3,K2O and Na2O contents.Besides,all samples show negative correlation between manganese and Al2O3contents.The trace elements of all samples show no enrichment relative to the upper crust content(UCC),except Th and U.Th/U ratios and authigenic Th/U ratios have similar stratigraphical tendency,with low Fe/Mn ratios,indicating that paleo-ocean environment was dominated by oxic-suboxic conditions.UCC-normalized REE+Y patterns are flat,showing no Ce anomaly(Ce/Ce*=1.00±0.02,n=39)and low Y/Ho ratios.Initial 87Sr/86Sr ratios of Mn ore belt are between 0.713383 and 0.725378,having an average value of 0.720180,showing a negative correlation with Al2O3contents.Comprehensive sedimentary and geochemical analyses show that Mn sourced from both hydrothermal fluids and continental weathering input.Manganese sources,combined with paleoocean oxidation and sea level fluctuations,controlled the Gaoyuzhuang manganese ore. |
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| Keywords: | Qinjiayu Gaoyuzhuang Formation manganese ore paleoenvironment geochemistry |
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