Phosphogenesis of phosphorite from the Sinian Doushantuo Formation in Guizhou Province and its coupling relation with the Neoproterozoic Oxygenation Event
Zhang Ya-Guan1,2, Du Yuan-Sheng2,3, Liu Jian-Zhong2,4, Wang Ze-Peng2,5, Deng Chao6
1 School of Earth Resources,China University of Geosciences(Wuhan),Wuhan 430074,China; 2 Innovation Center of Ore Resources Exploration Technology in the Region of Bedrock,Ministry of Natural Resources of People's Republic of China,Guiyang 550081,China; 3 State Key Laboratory of Biogeology and Environmental Geology,School of Earth Sciences,China University of Geosciences(Wuhan),Wuhan 430074,China; 4 Bureau of Geology and Mineral Exploration and Development of Guizhou Province,Guiyang 550004,China; 5 Geological Brigade 105,Bureau of Geology and Mineral Exploration and Development of Guizhou Province,Guiyang 550018,China; 6 Geological Brigade 115,Bureau of Geology and Mineral Exploration and Development of Guizhou Province,Guizhou Qingzhen 551400,China
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.
Fund:Co-funded by United Foundation of the National Natural Science Foundation of China(No.U1812402),program of Team of Scientific and Technological Innovation Talents on the Prediction and Evaluation of Manganese Resources in Guizhou Province and scientific research project of Bureau of Geology and Mineral Exploration and Development of Guizhou Province(No. [2016]10)
Corresponding Authors:
Du Yuan-Sheng,born in 1958,professor and Ph.D. supervisor of China University of Geosciences(Wuhan),is mainly engaged in sedimentary geology and sedimentary minerals. E-mail: duyuansheng126@126.com.
About author: Zhang Ya-Guan,born in 1990,postdoctoral fellow at China University of Geosciences(Wuhan),is mainly engaged in sedimentary geology and sedimentary minerals. E-mail: zyg1000800@sina.cn.
Cite this article:
Zhang Ya-Guan,Du Yuan-Sheng,Liu Jian-Zhong et al. Phosphogenesis of phosphorite from the Sinian Doushantuo Formation in Guizhou Province and its coupling relation with the Neoproterozoic Oxygenation Event[J]. JOPC, 2020, 22(5): 893-912.
Zhang Ya-Guan,Du Yuan-Sheng,Liu Jian-Zhong et al. Phosphogenesis of phosphorite from the Sinian Doushantuo Formation in Guizhou Province and its coupling relation with the Neoproterozoic Oxygenation Event[J]. JOPC, 2020, 22(5): 893-912.
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