| Bankole, Olabode M., El Albani, Abderrazak, Meunier, Alain, Gauthier-Lafaye, François (2015) Textural and paleo-fluid flow control on diagenesis in the Paleoproterozoic Franceville Basin, South Eastern, Gabon. Precambrian Research, 268. 115-134 doi:10.1016/j.precamres.2015.07.008 | Journal (article/letter/editorial) | Paleoproterozoic Franceville Basin, South Eastern, Gabon Olabode M. Bankole a,∗ , Abderrazak El Albani a...Basin Gabon a b s t r a c t The Paleoproterozoic (∼2.15 Ga) Franceville Basin, South Eastern Gabon, is...petrographic distinct generations of the precipitated illite and chlorite suggesting their precipitation from...equilibrium homogenous pore-fluid. The predominance of 1Mt illite polytype in most lithologies reflects precipitation...the main crystallized authigenic minerals aside illite and Fe-rich chlorite clay minerals. The mineralogical | | | Journal (article/letter/editorial) | uraninite in the natural fission reactors in Gabon J. ‘Department JANECZEK’ and R. C. EWING’ ‘Faculty of...uranium ore from the natural fission reactors in Gabon were studied by detailed electron microprobe analysis...Ru. INTRODUCTION it has also been recognized at Oklo (Havette et al., 1975; Lancelot et al., 1975; Devillers...loss from uraninite, the U-P\, ages of U ore at Oklo range from 1780 Ma to 2050 Ma (Naudet, 1991). A...1993b). The major episode of Pb mobilization at Oklo has been related to the intrusion of a dolerite | | | Journal (article/letter/editorial) | Kenji Horie a , Françoise Gauthier-Lafaye c a Department of Earth and Planetary Systems Science, Hiroshima...isotopic analyses. Illite grains found in calcite veins included in sandstone near the Oklo uranium deposit...deposit, Republic of Gabon, show extremely low 207Pb/206Pb (∼ 0.0158) isotopic ratios. Although the Pb isotopic...coexisting with illite indicate the formation age of each component, those of illite do not. In addition...addition, illite grains having low 207Pb/206Pb isotopic ratios contain a strongly large amount of Ba (1230 | | | Journal (article/letter/editorial) | in micro-minerals bearing fission products in the Oklo and Bangombé natural reactors: A review of a natural...migration of fission products H. Hidaka ∗ , M. Kikuchi Department of Earth and Planetary Systems Science, Hiroshima...Natural reactor Gabon Migration a b s t r a c t In the Precambrian, parts of the Oklo, Okélobondo and...Republic of Gabon, central Africa, functioned as natural fission reactors. Many elements in the Oklo and Bangombé...analyses on micro-minerals found in and around the Oklo and Bangombé natural reactors are reviewed in this | | | Journal (article/letter/editorial) | Ma ago. The model explaining the formation of the Oklo uranium deposits suggests that at the time of sediment...Paleoproterozoic; Uranium; Manganese; Atmosphere; Oklo; Gabon; Carbon isotopes; Black shales 1. Introduction...Introduction The natural nuclear fission reactors in Gabon are unique. The possibility that nuclear fission reactions...occur 2.0 Ga ago in the Oklo uranium deposit of the Francevillian Series, Gabon (Neuilly et al., 1972)...in the Paleoproterozoic uranium ore deposits of Gabon. This observation raises the question whether this | | | Report (chapter) | 2015 Special cases of natural analogues: The Gabon and Cigar Lake U ore deposits F. G A U T H I E R... Tokai-mura, Ibaraki-ken, Japan Abstract: The Gabon and Cigar Lake uranium deposits may be used as natural...clay matrix. Futhermore, the Oklo and Bangomb6 uranium deposits in Gabon were natural nuclear fission...explain the preservation of the natural reactors of Gabon and of the Cigar Lake deposit. The mineralogy of...Cigar Lake deposit and in the natural reactors of Gabon. Coffinitization may be related to hydrothermal | | | Journal (article/letter/editorial) | 1989, pp• 2286-2295 Natural Fission Reactors of Oklo F. GAUTHIER-LAFAYE, F. WEBER, Centrede Sddimentologie...famous and the first discovered are those in the Oklo uranium ore deposit.Petrographic,geochemical,and...fissionreactionsat Oklo is characterizedby a gangueof clay minerals,whereasthe normalore of Oklo consistsof sandstones...stabledaughterisotopes. The nuclear phenomenonat Oklo is unique URANIUMwith an abnormalisotopiccomposition...sionproductsstoredin a geologicenvironmentfor a deposit (Gabon) in 1972 by the Commissariat?t geologicallysignificantperiod | | | Journal (article/letter/editorial) | Review A Review of In Situ Isotopic Studies of the Oklo and Bangombé Natural Fission Reactors Using Microbeam...Microbeam Analytical Techniques Hiroshi Hidaka Department of Earth and Planetary Sciences, Nagoya University...fission products, have been found in and around the Oklo and the Bangombé natural reactors. In the past two...compositions of various elements in and around the Oklo and Bangombé natural reactors vary significantly...like to review the isotopic results related to the Oklo and Bangombé reactors mainly based on my works using | | | Journal (article/letter/editorial) | Natural fission reactors in the Franceville basin, Gabon: A review of the conditions and results of a "critical...deposits in the world, the Oklo and Bangomb6 deposits of the Franceville basin: Gabon. Since 1982, five new...over a long period of time. Therefore, the sites of Oklo and Bangomb6 are well preserved. For the reactors...program was initiated as a European Community project "Oklo: Natural analogue." These studies attempted to reconstruct...Franceville basin, Gabon, namely Oklo and Bangomb6. During the seventies, the Oklo natural fission reactors | | | Journal (article/letter/editorial) | 155–174 Hydrothermal and supergene clays of the Oklo natural reactors: conditions of radionuclide release...surrounding two natural fission reactors of the Oklo deposit. In the deeply preserved reactor 10 Ž450...Elsevier Science B.V. All rights reserved. Keywords: Oklo; Nuclear waste; Clays; Weathering; O-isotopes; Fission...fission reactors located in the uranium deposits of Gabon constitute an unique opportunity to study the long...have been recognised in the Oklo open pit and in the deeper Oklo–Okelobondo mine Ž200–600 m deep.. In the | | | Journal (article/letter/editorial) | fissiogenicREEs from a natural fission reactor at Bangomb6,Gabon hxusz JlNsczrrt .nxoRonNrv C. Ewrxc2 'Faculty of...florencite-(ce) (Lalce : 0.62) have been identified in illite from the clay mantle surrounding a natural, 2 Ga...monazite-(Ce),apatite, TiO, (probably anatase),zircon, and illite. Grains of florencite-(Ce)contain inclusions of...deposits of the Franceville Basin in southeastern Gabon at approximately2 Ga andlasted 105-106yr, producinga...fission-reactor zones have been discovered in the U deposit at Oklo since 1972. Two more reactorsare known at Okelobondo | | | Journal (article/letter/editorial) | phases and bitumen in the Oklo Proterozoic natural fission reactors, Gabon JOHN PARNELL School of Geosciences...the Proterozoic natural fission reactors at Oklo, Gabon contain abundant organic matter (bitumen), with...bitumen, uranium, Oklo, Gabon. Introduction TllE uranium ore deposits at Oklo, Gabon, are unique in including...the migration and retention of elements about the Oklo reactors. Work on fissiogenic isotopes shows that....... i :ili~Libreville 0~ F GABON -::I" - 1 ,:.."" N 5~3 4 Oklo ;\ 2" "2-.... " 9 "2:.... | | | Journal (article/letter/editorial) | os de Caldas, Cigar Lake, Maqarin, El Berrocal, Oklo and Palmottu. To make this comparison meaningful...primary uranium mineralisations (Enresa, 1996); Oklo (Gabon), a fossil natural nuclear reactor systems located...carried out to date. For example, the studies at Oklo and Palmottu were completed only during 1999. Consequently...BPM exercises, from the Pocß os de Caldas to the Oklo and Palmottu projects, has not varied significantly...(Spain), CSIC (Spain) and MBT/QuantiSci (Spain). Oklo: CEA (France), Ciemat (Spain), CNRS (France), CSIC | | | Journal (article/letter/editorial) | radiolysis on local redox conditions in the Oklo, Gabon, natural fission reactors 10 and 16 CREGU VI~RONIQIJE...significantly modify the local redox conditions. The Oklo natural fission zones are good examples where the...claimed that, in the conditions of the operating Oklo reactors, there had been the same recombination...matter was not considered in these calculations. The Oklo nuclear fission zones are excellent sites for studying...spectroscopy. r c Libreville c GABON 1 t r Q 500 m i OKLO \ - ’ _,.., . . . 6 Manganese 0 | | Ossa Ossa, Frantz, Hofmann, Axel, Vidal, Olivier, Kramers, Jan D., Agangi, Andrea, Belyanin, Georgy A., Mayaga-Mikolo, Francis (2014) Hydrothermal clay mineral formation in the uraniferous Paleoproterozoic FA Formation, Francevillian basin, Gabon. Precambrian Research, 246. 134-149 doi:10.1016/j.precamres.2014.03.003 | Journal (article/letter/editorial) | Paleoproterozoic FA Formation, Francevillian basin, Gabon Frantz Ossa Ossa a,∗ , Axel Hofmann a , Olivier...Georgy A. Belyanin a , Francis Mayaga-Mikolo c a Department of Geology, University of Johannesburg, Auckland...Ministère de l’Industrie et des Mines, Libreville, Gabon b a r t i c l e i n f o Article history: Received...Formation of the Francevillian basin, south-east Gabon, which hosts high-grade U ore deposits associated...only known occurrence of natural nuclear reactors. Illite appears as the main clay phase in the lower fluvial | | | Journal (article/letter/editorial) | K-feldspar leads to in situ crystallixation of illite and chlorite as well as neodymium isotopic equilibration...organic-rich black shales of the Francevillian basin in Gabon have been selected. Geochemical and isotope studies...Franceviliian black shales. (b) Aothigenic clay minerals (illite, chlorite) located in the matrix of the black shales...Replacement of detrital K-feldspar (microcline) by illite and chlorite. tNd values of -6.5 I + 2.02 and...dates correspond to the age of crystallization of illite and chlorite minerals during incipient diagenesis | | | Journal (article/letter/editorial) | Hidaka a,b,c,*, Francßois Gauthier-Lafaye c b a Department of Earth and Planetary Systems Science, Hiroshima...isotopic studies of the Oklo and Bangombé natural fission reactors in east Gabon provide information on...INTRODUCTION The Oklo, Okelobondo, and Bangombé uranium deposits in the Republic of Gabon, central Africa...radioactive waste. * Corresponding author. Address: Department of Earth and Planetary Systems Science, Hiroshima...also clay minerals from the peripheral rocks of the Oklo and Bangombé RZs were performed, because clay minerals | | | Journal (article/letter/editorial) | LOWER PROTEROZOIC SEDIMENTS: THE FRANCEVILLIAN IN GABON M.G. BONHOMME, F. GAUTHIER-LAFAYE and F. WEBER...Lower Proterozoic sediments: the Francevillian in Gabon. Precambrian Res., 18: 87--102. New mineralogical...the upper part o ~ t h e Ogoo~ River basin in the Gabon Republic. The discovery, in 1972, of natural nuclear...nuclear reactors in the uranium ore deposit at Oklo (Bodu et al., 1972; Neuilly et al., 1972) increased...dating technique using fission products f o u n d at Oklo. These methods reveal an age of ca. 2000 Ma (DeviUers | | Loss, R.D., Rosman, K.J.R., De Laeter, J.R., Curtis, D.B., Benjamin, T.M., Gancarz, A.J., Maeck, W.J., Delmore, J.E. (1989) Fission-product retentivity in peripheral rocks at the Oklo natural fission reactors, Gabon. Chemical Geology, 76 (1) 71-84 doi:10.1016/0009-2541(89)90128-9 | Journal (article/letter/editorial) | retentivity in peripheral rocks at the Oklo natural fission reactors, Gabon R.D. LOSS 1'.1, K.J.R. ROSMAN 1...retentivity in peripheral rocks at the Oklo natural fission reactors, Gabon. Chem. Geol., 76: 71-84. Thermal...the immediate vicinity of Reactor Zone 9 at the Oklo mine site. The mass spectrometric isotope dilution...occurring fission reactors found at the Oklo uranium mine in Gabon, Southwest Africa (De Laeter, 1985)....Ruffenach et al., 1980). 1.1. Setting The Oklo uranium mine is located in the Francevillian Basin in the | | | Journal (article/letter/editorial) | Proterozoic black shales of the Franceville basin (Gabon) F. Gauthier-Lafaye *, R. Bros, P. Stille Centre...performed on authigenic < 0.4-p~m clay fractions (illite 1M, Fe-Mg-chlorite) extracted from black shales...Francevillian (lower Proterozoic) sedimentary series in Gabon. The clay residues and acid leachates (1 N HC1)...Francevillian series is located in southeastern Gabon and unconformably overlies an Archean crystalline...crystalline basement (2.6-3 Ga) represented by the North Gabon and Chaillu massifs (Fig. 1; Bonhomme et al., 1982; | | | Journal (article/letter/editorial) | beneath a natural fission reactor at Bangomb6, Gabon JANUSZ JANECZEK RODNEY EWING SPONTANEOUS fission...reactions occurred in several uranium deposits in SE Gabon approximately two billion years ago. The reactor...consist of high-grade uranium ore mantled by illite Department of Earth Sciences, University of Silesia...uL Bedzinska 60, PL-41-200 Sosnowiec, Poland Department of Earth and Planetary Sciences, University of...fission reactor at Bangomb6 (20 km south of the Oklo uranium deposit), we have found several grains of | | | Journal (article/letter/editorial) | nucleogenic Pu in apatite and Pb evolution at the Oklo natural reactor KENJI HORIE,1 HIROSHI HIDAKA,*,1...1 and FRANÇOIS GAUTHIER-LAFAYE2 1 2 Department of Earth and Planetary Systems Science, Hiroshima University...of the boundary layer of reactor zone 10 at the Oklo natural reactor shows a unique petrologic texture...Hidaka and Holliger, 1998). Isotopic data from the Oklo RZ samples provide key information to identify the...tens m. Previous results from SIMS analysis of Oklo samples suggest a significant role of selective | | Bros, R., Turpin, L., Gauthier-Lafaye, F., Holliger, Ph., Stille, P. (1993) Occurrence of naturally enriched 235U: Implications for plutonium behaviour in natural environments. Geochimica et Cosmochimica Acta, 57 (6) 1351-1356 doi:10.1016/0016-7037(93)90072-5 | Journal (article/letter/editorial) | took place 2.0 Ga ago in the OkIo uranium deposit (Gabon). New isotope investigations show that clay minerals...rocks neighbouring the natural fission reactor 10 at Oklo have depleted 235Uwith z35U/238U ratios ranging...enrichment in uranium ore originating from reactor 10 of Oklo, which was discovered in 198 1 (Fig. 1). The 235U...uranium deposits at Oklo, Gabon (BODU et al., 1972; NEUILLY et al., 1972). At Oklo, “‘U depletion occurred...reactions acted. Such a depletion was significant at Oklo, inducing a 235U/238Uratio as low as 0.0029 ( NAUDET | | | Journal (article/letter/editorial) | SASKATCHEWAN, CANADA P. ALEXANDRE† AND T. K. KYSER Department of Geological Sciences and Geological Engineering...elsewhere (e.g., the “natural fission reactors” at Oklo, Gabon: Mossman et al., 1993a; in uranium occurrences...Cree Lake mobile zone, situated between the Rae province and the Trans-Hudson orogen (Lewry and Sibbald...rims, was followed by a late diagenetic stage of illite that replaced kaolinite (Fig. 3C) and by minor...precipitation and chlorite alteration of kaolinite and illite (Fig. 4). The main mineralization event was characterized | | Mouélé, Idalina Moubiya, Dudoignon, Patrick, Albani, Abderrazak El, Martin, Hervé, Paquette, Jean-Louis, Cuney, Michel, Gauthier-Lafaye, François (2013) The Archean Granitoid-Paleoproterozoic Unconformity: Superimposition of Alteration Events in Archean Granitoids, Gabon. Procedia Earth and Planetary Science, 7. 598-601 doi:10.1016/j.proeps.2013.03.175 | Journal (article/letter/editorial) | superimposition of alteration events in Archean granitoids, Gabon Idalina Moubiya Mouéléa*, Patrick Dudoignona, Abderrazak...France Abstract The Archean granitoids of the South Gabon, dated from 3.0-to-2.5 Ga, were examined along the...that was drill cored in the Franceville basin (Gabon). The previous studies performed in the Francevillian...affected by diagenetic event which is characterized by illite and chlorite new-formations, quartz overgrow, accessory...the Northeast part of the Congo craton, and South Gabon. This massif is composed of heterogeneous granitoids |
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