Cryptic sediment-hosted critical element mineralization from eastern Yunnan Province,southwestern China: Mineralogy,geochemistry, relationship to Emeishan alkaline magmatism and possible origin |
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| Institution: | 1. State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology (Beijing), Beijing 100083, China;2. School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia;3. Yunnan Institute of Coal Geology Prospection, Kunming 650218, China;4. University of Kentucky, Center for Applied Energy Research, Lexington, KY 40511, United States;1. Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China;2. Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences), Ministry of Education, Wuhan 430074, China;3. College of Earth Sciences, Jilin University, Changchun 130061, China;4. Department Applied Geosciences and Geophysics, Montanuniversität Leoben, Peter-Tunner-Str. 5, A-8700 Leoben, Austria;5. Oil and Gas Survey, China Geological Survey, Beijing 100083, China;1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China;2. Department of Earth and Environmental Sciences, University of St. Andrews, St. Andrews KY16 9AL, UK;3. Centre for Exploration Targeting, School of Earth and Environment, University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia;4. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China;5. College of Earth Science, Chengdu University of Technology, Chengdu 610059, China;1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China;2. School of Earth, Atmosphere & Environment, Monash University, Melbourne, VIC 3800, Australia;3. College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China;4. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China;1. Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;2. University of Chinese Academy of Sciences, Beijing 100039, China |
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| Abstract: | A previous study briefly described the occurrence of a new type of Nb(Ta)-Zr(Hf)-REY-Ga (REY: rare earth elements and yttrium) polymetallic mineralization in eastern Yunnan, southwest China. In this paper, the mineralogical and geochemical features have been further advanced through a study of two regionally extensive and relatively flat-lying mineralized layers from No. XW drill core. The layers are clay-altered volcanic ash and tuffaceous clay, and are dominated by clay minerals (mixed layer illite/smectite, kaolinite, berthierine, and chamosite); with lesser amounts of quartz and variable amounts of anatase, siderite and calcite; along with trace pyrite, barite, zircon, ilmenite, galena, chalcopyrite, and REE-bearing minerals. The mineralized samples have higher Al2O3/TiO2 values (13.7–41.4) and abundant rare metal elements (Nb, Ta, Zr, Hf, REE, Ga, Th, and U) whereas less mineralized samples are rich in V, Cr, Co, and Ni and have lower Al2O3/TiO2 values (2.32–7.67). The mineralized samples also have strong negative δEu in chondrite-normalized REE patterns. Two processes are most likely responsible for the geochemical and mineralogical anomalies of the mineralized samples: airborne volcanic ash and multi-stage injection of low-temperature hydrothermal fluids. Based on paragenetic analysis, this polymetallic mineralization is derived from the interaction between alkaline volcanic ashes and subsequent percolation of low-temperature fluids. The intense and extensive alkaline volcanism of the early Late Permian inferred from this study possibly originated from the coeval Emeishan large igneous province (ELIP). This unique Nb(Ta)-Zr(Hf)-REE-Ga mineralization style has significant economic and geological potential for the study of mineralization of the lowest Xuanwei Formation. |
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