Comparison between Datangpo-type manganese ores and modern marine ferromanganese oxyhydroxide precipitates based on rare earth elements |
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| Institution: | 1. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Science, Guiyang, 550081 Guiyang, China;2. School of Earth Sciences and Resources, China University of Geosciences, Beijing, Haidian, 100083 Beijing, China;3. University of Chinese Academy of Sciences, Beijing, Haidian, 100049 Beijing, China;1. Key Laboratory of Mineral Resource, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China;3. Department of Earth Science, University of Ghana, P.O. Box LG 58, Legon-Accra, Ghana;1. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences-Wuhan, Wuhan 430074, China;2. School of Earth Sciences, China University of Geosciences, Wuhan 430074, China;3. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences-Wuhan, Wuhan 430074, China;4. Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013, USA;5. Guizhou Bureau of Geology and Mineral Exploration and Development, Guiyang 550004, China;6. 103 Geological Party, Guizhou Bureau of Geology and Mineral Exploration and Development, Tongren 554300, China;1. MLR Key Laboratory of Isotope Geology, State Key Laboratories of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;2. School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-6004, USA;3. Department of Earth and Environmental Sciences, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L 3G1, Canada;4. State Key Laboratories of Biogeology and Environmental Geology and Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China;5. Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013, USA;1. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China;2. School of Energy Resources, China University of Geosciences, Beijing 100083, China;3. School of Marine Sciences, Sun Yat-sen University, Guangzhou 510006, China;4. Asian Tectonics Research Group, Key Laboratory of Computational Geodynamics, College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China;1. State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210046, China;2. Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen, Denmark;3. Nordic Center for Earth Evolution, NordCEE, Denmark |
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| Abstract: | Datangpo-type sedimentary manganese deposits, which are located in northeastern Guizhou province and its adjacent areas, are Mn carbonate-type deposits hosted in black carbonaceous shale that represent a series of medium to large deposits containing a huge tonnage of reserves. PAAS-normalized rare earth element distribution patterns of manganese ores record “hat-shaped” REY (REE + Y) plots characterized by pronounced middle rare earth element enrichment, evident positive Ce anomalies, weak to strong positive Eu anomalies and negligible negative Y anomalies. These REY geochemical characteristics are different from those of country rocks and record the processes and features of sedimentation and diagenesis. Manganese was precipitated as Mn-oxyhydroxide particles in oxidized water columns with the sorption of a certain amount of rare earth elements, subsequently transforming from Mn-oxyhydroxides to rhodochrosite and redistributing REY in reducing alkaline pore-water during early diagenesis. A number of similarities can be observed through a comparison of Datangpo-type manganese ores and modern marine ferromanganese oxyhydroxide precipitates based on their rare earth elements. The precipitation of Datangpo-type manganese ores is similar to that of hydrogenetic crusts and nodules based on their positive Ce anomalies and relatively higher total REY concentrations. However, several differences also exist. Compared to hydrogenetic crusts and nodules, Datangpo-type manganese ores record smaller positive Ce anomalies, lower total REY concentrations, unobvious fractionation between Y and Ho, and weak to strong positive Eu anomalies. These were caused by quicker sedimentary rates in the oxic water columns of the shallower basin, after which pore water became strongly reducing and alkaline due to the degradation of organic matter in the early diagenetic stage. In addition, compared to typical deposits in the world, Datangpo-type manganese ores are similar to hydrogenetic deposits and different than hydrothermal deposits. All of these characteristics of manganese ores indicate that Datangpo-type manganese ores, the principal metallogenic factors of which include oxidation conditions during deposition and reducing conditions during early diagenetic stages, represent hydrogenetic deposits. |
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| Keywords: | Manganese deposits Marine ferromanganese precipitates Deposit genesis REE geochemistry |
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