Geological,geochemical and mineralogical characteristics of REE-bearing Las Mercedes bauxite deposit,Dominican Republic |
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| Institution: | 1. Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Geologia, Universitat de Barcelona (UB), Martí i Franquès s/n, 08028 Barcelona, Spain;2. Departamento de Mineralogía y Petrología, Universidad de Granada, Av. Fuentenueva s/n, 18002 Granada, Spain;3. Instituto Andaluz de Ciencias de la Tierra, CSIC-UGR, Av. de las Palmeras, 4, 18100 Armilla, Granada, Spain;4. Department of Earth and Environmental Sciences, George Washington University, Washington, DC 20052, USA;1. Center for Electron Nanoscopy, Technical University of Denmark, 2800 Kongens Lyngby, Denmark;2. Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, Zografou Campus, 15784 Athens, Greece;3. Department of Geology & Mineral Engineering, Norwegian University of Science & Technology, 7491 Trondheim, Norway;4. Department of Physics, University of Ioannina, 45110 Ioannina, Greece;5. ANKA Synchrotron Radiation Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany;6. Karlsruhe Institute of Technology, Institute for Chemical Technology and Polymer Chemistry, Kaiserstrasse 12, 76131 Karlsruhe, Germany;7. KU Leuven, Department of Materials Engineering, Kasteelpark Arenberg 44, 3001 Leuven, Belgium;8. Department of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece |
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| Abstract: | Bauxite deposits, traditionally the main source of aluminum, have been recently targeted for their remarkable contents in rare earth elements (REE). With ∑REE (lanthanoids + Sc + Y) concentrations systematically higher than ～1400 ppm (av. = 1530 ppm), the Las Mercedes karstic bauxites in the Dominican Republic rank as one of the REE-richest deposits of its style.The bauxitic ore in the Las Mercedes deposit is mostly unlithified and has a homogeneous-massive lithostructure, with only local cross-stratification and graded bedding. The dominant arenaceous and round-grained texture is composed of bauxite particles and subordinate ooids, pisoids and carbonate clasts. Mineralogically, the bauxite ore is composed mostly of gibbsite and lesser amounts of kaolinite, hematite, boehmite, anatase, goethite, chromian spinel and zircon. Identified REE-minerals include cerianite and monazite-Ce, whose composition accounts for the steady enrichment in light- relative to medium- and heavy-REE of the studied bauxites.Considering the paleo-geomorphology of the study area, we propose that bauxites in the Las Mercedes deposit are the product of the erosion and deposition of lithified bauxites located at higher elevations in the Bahoruco ranges. Based on the available data, we suggest a mixed lithological source for the bauxite deposits at the district scale: bedrock carbonates and an igneous source of likely mafic composition. |
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| Keywords: | Karstic bauxite REE High tech metals Dominican Republic |
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