U/Pb age and origin of supergene uranophane-beta from the Borborema Pegmatite Mineral Province,Brazil |
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| Affiliation: | 1. Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Praha 2, Czech Republic;2. BRGM, Avenue Claude Guillemin, 45082 Orléans Cedex 2, France;3. Czech Geological Survey, Geologická 6, 152 00 Praha 5, Czech Republic;4. Department of Soil Science and Soil Protection, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Praha 6, Czech Republic;5. Department of Geology, Faculty of Science, Palacký University in Olomouc, 17. listopadu 12, 771 46 Olomouc, Czech Republic;6. Department of Geology, Faculty of Science, University of Namibia, Private Bag 13301, Windhoek, Namibia;7. University of Zambia, School of Mines, P. O. Box 32 379, Lusaka, Zambia;1. Zavaritsky Institute of Geology and Geochemistry, Ural Branch of the Russian Academy of Sciences, Pochtovyi per. 7, Yekaterinburg, 620075, Russia;2. A.P. Karpinsky Russian Geological Research Institute, Srednii pr. 74, St. Petersburg, 199106, Russia;3. GEMOC ARC National Key Centre, Macquarie University, Sydney, Australia |
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| Abstract: | Uranophane-beta of supergene origin formed in the Borborema Pegmatite Mineral.Province, which is situated in the north-easternmost part of Brazil. The sampling site lies in the topmost parts of the Quintos Pegmatite, about ten kilometers north of the town of Equador. The uranyl silicate was investigated for its age and physical chemical regime of formation. Age dating yielded a U/Pb age of 6.77 ± 0.61 Ma. Uranophane has been derived together with autunite from weathering of brannerite in a tropical climate under alternating wet and dry seasons, when the pH was below 8. This canary-yellow well-crystallized uranyl silicate can be used as a physical chemical marker as well as a clock for supergene alteration. |
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| Keywords: | Uranophane Weathering Neogene Borborema province North-eastern Brazil |
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