| 贵州震旦系陡山沱组磷块岩成磷作用及与新元古代末期氧化事件(NOE)的耦合* |
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| 引用本文： | 张亚冠,杜远生,刘建中,王泽鹏,邓超.贵州震旦系陡山沱组磷块岩成磷作用及与新元古代末期氧化事件(NOE)的耦合*[J].古地理学报,2020,22(5):893-912. |
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| 作者姓名： | 张亚冠 杜远生 刘建中 王泽鹏 邓超 |
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| 作者单位： | 1.中国地质大学(武汉)资源学院,湖北武汉 430074;2.自然资源部基岩区矿产资源勘查工程技术创新中心,贵州贵阳 550081;3.生物地质与环境地质国家重点实验室,中国地质大学(武汉)地球科学学院,湖北武汉 430074;4.贵州省地质矿产勘查开发局,贵州贵阳 550004;5.贵州省地质矿产勘查开发局105地质大队,贵州贵阳 550018;6.贵州省地质矿产勘查开发局115地质大队,贵州清镇 551400 |
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| 基金项目： | *国家自然科学基金联合基金项目(编号: U1812402)、贵州省锰矿资源预测评价科技创新人才团队项目和贵州省地质矿产开发局地质科研项目(黔地矿科合[2016]10号)联合资助 |
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| 摘 要： | 新元古代末期历经“雪球地球”和大气、海洋增氧事件后,发生了全球性成磷事件,贵州省震旦系陡山沱组大规模磷矿床沉积是本次成磷事件的典型代表。然而现阶段对贵州陡山沱组磷块岩成磷作用机制研究存在诸多争议,成磷事件与同期古海洋环境转变之间的关联研究也较为薄弱。作者以贵州省瓮安、遵义和丹寨地区陡山沱组原生磷块岩为研究对象开展的沉积学、岩石学、矿物学和地球化学特征研究表明: 陡山沱早期成磷作用被限制在浅水海岸,瓮安地区A矿层球粒磷块岩中大量的含铁自生矿物黄铁矿、海绿石以及无Ce负异常指示的贫氧沉积水体环境均表明,Fe-氧化还原泵成磷模式在富磷过程中发挥了重要作用;陡山沱晚期磷块岩分布扩散至较深水陆棚—斜坡沉积相区,磷块岩与富有机质岩层共生,矿物晶体形态特征与矿石内富含的大量生物化石均表明,有机质沉降聚磷作用和生物成磷作用促使磷块岩大量沉积,较明显的Ce负异常值也指示了海水氧气含量的提升。成磷作用模式的转变和磷块岩分布的扩展是对海洋增氧事件的沉积响应,同时造成的多细胞动物演化也影响了深部水体的氧化还原状态,进而反映了贵州省陡山沱组磷块岩大规模沉积与新元古代末期氧化事件(NOE)密切的耦合关系。
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| 关 键 词： | 震旦纪 陡山沱组 磷块岩 成磷作用 新元古代末期氧化事件 |
| 收稿时间： | 2020-06-19 |
Phosphogenesis of phosphorite from the Sinian Doushantuo Formation in Guizhou Province and its coupling relation with the Neoproterozoic Oxygenation Event |
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| Zhang Ya-Guan,Du Yuan-Sheng,Liu Jian-Zhong,Wang Ze-Peng,Deng Chao.Phosphogenesis of phosphorite from the Sinian Doushantuo Formation in Guizhou Province and its coupling relation with the Neoproterozoic Oxygenation Event[J].Journal of Palaeogeography,2020,22(5):893-912. |
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| Authors: | Zhang Ya-Guan Du Yuan-Sheng Liu Jian-Zhong Wang Ze-Peng Deng Chao |
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| Abstract: | Phosphate deposits of the Ediacaran Doushantuo Formation accumulated in the central Guizhou Province are the typical phosphate-rich sediments during the Neoproterozoic Phosphogenic Episodes,which occurred after the “Snowball Earth”period and Neoproterozoic Oxygenation Event. However,the mechanisms of phosphate enrichment in seawater have always been hotly debated,and the research for correlations between phosphogenesis and transition of Ediacaran palaeo-ocean environments is still unsubstantial. This study focused on the sedimentological,petrological,mineralogical and geochemical analyses on the Doushantuo pristine phosphorite in Weng'an,Zunyi and Danzhai area. Documented by spherulitic phosphorites in the Lower Phosphorite beds from Weng'an area that contain abundant autogenetic Fe-bearing minerals such as pyrite and glauconite and show weak Ce negative anomaly,Fe-redox pumping in low-oxygen environments are the important phosphogenesis mechanism but only limited in coastal waters in the Early Doushantuo Period. Phosphorite in the Upper Phosphorite beds deposited within organic-rich beds and contain massive biological fossils suggests that phosphogenesis might have been triggered by degradation of organic matter and biological action in the Late Doushantuo Period,and distribution of phosphatic sediments extended to the deeper shelf to slope setting. Obvious Ce negative anomaly implies the increase of oxygen content in seawater. The transition of phosphogenesis mechanisms and the expansion of phosphorite deposits are the sedimentary response of ocean oxygenation,and the associated evolution of metazoans also changed the redox conditions of the deep seawater. These sedimentary and geochemistry data reflect the closed coupling relation between Doushantuo phosphorite in Guizhou Province and the Neoproterozoic Oxygenation Event. |
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| Keywords: | Ediacaran Doushantuo Formation phosphorite phosphogenesis Neoproterozoic Oxygenation Event |
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