1 u deposits sandstones looking forward cuney
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Austria conference 2012-Uranium Sandstone

Austria conference 2012-Uranium Sandstone

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  • Le bassin sédimentaire de Franceville est situé au Sud-Est du Gabon. De forme elliptique, il est allongé selon un axe NW-SE sur environ 135 km. 16 zones de réaction nucléaires ont été découvertes dans la carrière d ’Oklo, 1 dans la mine d ’Okélobondo et 1 dernière dans la carrière de Bangombé
  • La série francevillienne repose sur un socle cristallin archéen. Elle est composée de 5 formations indexées de FA à FE. La minéralisation uranifère est localisée au toit des grès du FA, sous les pélites du FB.
  • Les 17 réacteurs nucléaires naturels découverts dans la carrière d ’Oklo et la mine d ’Okélobondo appatiennent à une couche minéralisée des grès au sommet de la formation FA sous les pélites du FB. Tous ces réacteurs sauf une partie du R2 ont été exploités.

1 u deposits sandstones looking forward cuney Presentation Transcript

  • 1. Sandstone uranium deposits: Looking forward Michel CUNEY UMR G2R – CREGU – CNRS Vandoeuvre les NANCY
  • 2. PRESENTATION HIGHLIGHTS To propose a general framework for the different types of uranium depositsassociated with sandstone within the continuum of the geologic cycle To try to go beyond the usual classifications using the recent work of the UDEPOgroup and more personal viewsSuch a general framework should help to set up the different contributions whichwill be presented during this meeting concerning deposits from all over the world To trace the avenues for future research and exploration of sandstone relateddeposits
  • 3. IAEA classification 20121. Intrusive2. Granite-related3. Polymetallic iron-oxide breccia complex4. Volcanic-related5. Metasomatite6. Metamorphite7. Proterozoic unconformity: 82 deposits8. Collapse-breccia pipe (Arizona Strip, USA)9. Sandstone: 576 deposits from 1405 compiled in the UDEPO data base10. Paleo-quartz-pebble conglomerate: 62 deposits11. Surficial: 60 deposits12. Lignite and coal13. Carbonate14. Phosphate15. Black shale
  • 4. IAEA classification 20129. Sandstone9.1. Basal channel(Dalmatovskoye, Russian Federation; Beverley, Australia)9.2. TabularContinental fluvial, U associated with intrinsic reductant (Arlit type, Niger)Continental fluvial, U associated with extrinsic humate/bitumen (Grants type, USA)Continental fluvial vanadium-uranium (Salt Wash type, USA)9.3. RollfrontContinental basin, U associated with intrinsic reductant (Wyoming type, USA)Continental to marginal marine, U associated with intrinsic reductant (Chu-Saryisu type, Kazhakstan)Marginal marine, U associated with extrinsic reductant (South Texas, USA)9.4. Tectonic-lithologic(Lodève Basin, France; Franceville Basin, Gabon)9.5. Mafic dykes/sills in Proterozoic sandstone(Westmoreland District, Australia; Matoush, Canada)
  • 5. A GENETIC CLASSIFICATION OF U-DEPOSITS Cuney, 2012 1 – Fractional crystallization 2 – Partial melting 3 – Hydrothermal high level post-orogenic :  3A – Volcanic - hydrothermal  3B – Granitic - hydrothermal 4 – Diagenetic hydrothermal systems:  4C: Intraformational redox control 4C1: Tabular: Grants Mineral Belt, Beverley 4C2: Tectonolithologic: Akouta, Niger 4C3 : Karsts (breccia pipes): Colorado  4A: Basin/basement redox control (unconformity related)  4B: Interformational redox control (Oklo Gabon) but fluids similar to unconf. related U 5 - Hydrothermal metamorphic (Katanga deposits transitional with diagenetic hydrothermal systems)
  • 6. A GENETIC CLASSIFICATION OF U-DEPOSITS Cuney, 2012 6 – Hydrothermal metasomatic:  6A – Alkali-metasomatism  6B – Skarns :Mary Katheleen 7 – Syn-sedimentary:  7A: Mechanical sorting: Qz pebble conglomerates  7B: Redox trapping: black shales  7C: Crystal-chemical/redox trapping: phosphates 8 - Intraformational meteoric fluid infiltration  8A: Sealed paleovalleys: Vitim (Transbaikalia)  8B: Roll fronts: Powder River Basin (Wyoming) 9 –- Weathering & evapotranspiration: calcretes 10 – Other types
  • 7. U deposits related Calcretes /Lignite/Coal U deposits related to magmatic SURFACE WATERS to sedimentary Meteoric / Sea Conglomerates rocks Volcanic Phosphates basins IOCG(U) N Black shales O Basal Sandstone SI Ground Fract. cryst. Veins T EN waters Rollfront hosted Magmatic- Fluid EX DI Hydrothermal MIXING AG Tabular Tabular Fluids EN Formation ES waters Tectonolithol - IS . Breccia Pipes N IO MAGMATIC FRACTIONATION DIAGENETIC ATMAGMATIC M HU FLUIDS FLUIDS EX GEOLOGIC CYCLE Unconformity CO CO L LL Crustal Metamorphic L.T. IIS SII M Metamorphic Skarns Skarns IS ON ON PH fluids Na-metasomatism - Alaskites Alaskites Silicate M OR Metamorphic H.T. Crust partial Partial melts TA melting Melting MIX I ME U deposits related NG Subduction fluids to metamorphism N Mantle TIO melting melting MANTLE UC BD MELTS / FLUIDS SU
  • 8. IAEA classification 20129. Sandstone9.1. Basal channel(Dalmatovskoye, Russian Federation; Beverley, Australia)9.2. TabularContinental fluvial, U associated with intrinsic reductant (Arlit type, Niger)Continental fluvial, U associated with extrinsic humate/bitumen (Grants type, USA)Continental fluvial vanadium-uranium (Salt Wash type, USA)9.3. RollfrontContinental basin, U associated with intrinsic reductant (Wyoming type, USA)Continental to marginal marine, U associated with intrinsic reductant (Chu-Saryisu type, Kazhakstan)Marginal marine, U associated with extrinsic reductant (South Texas, USA)9.4. Tectonic-lithologic(Lodève Basin, France; Franceville Basin, Gabon)9.5. Mafic dykes/sills in Proterozoic sandstone(Westmoreland District, Australia; Matoush, Canada)
  • 9. 9.1. Basal channel (Paleovalley): Vitim district, Russian Federation: RAR: 52,000 mt U, Speculative R.: 100,000 mt U8 deposits over 250km2 with 44,800mtU @ 0.05-0.3 %U, prognosticated R.: 60,000mt U, Khiagda: 15,500 mt UPaleochannels with up to 50 m thick Oligocene-Miocene colluvial to alluvial grey to multicoloredcarbonaceous clay-siltstone, sandstone, conglomerate, intercalated lignite seams. Pyrite and plant debris, ~0.8% CorgGeological map of the Khiagda ore field
  • 10. 9.1. Basal channelTypical cross-section through the Khiagda deposit. SW 60 km NE 0 0 30 basalt 60 U ore granite 90 m Neogene sediments (sand, silt, clay) grey oxidized reduced Source: Highly potassic calcalkaline Hercynian granites Transport: infiltrated meteoric fluids through permeable siliciclastic rocks Deposition: reduction by detrital organic matter (20 Ma to present)
  • 11. IAEA classification 20129. Sandstone9.1. Basal channel(Dalmatovskoye, Russian Federation; Beverley, Australia)9.2. TabularContinental fluvial, U associated with intrinsic reductant (Arlit type, Niger)Continental fluvial, U associated with extrinsic humate/bitumen (Grants type, USA)Continental fluvial vanadium-uranium (Salt Wash type, USA)9.3. RollfrontContinental basin, U associated with intrinsic reductant (Wyoming type, USA)Continental to marginal marine, U associated with intrinsic reductant (Chu-Saryisu type, Kazhakstan)Marginal marine, U associated with extrinsic reductant (South Texas, USA)9.4. Tectonic-lithologic(Lodève Basin, France; Franceville Basin, Gabon)9.5. Mafic dykes/sills in Proterozoic sandstone(Westmoreland District, Australia; Matoush, Canada)
  • 12. 9.1. Basal channel looking forward Model mainly discovered in Russia with some other minor occurrences in NWMongolia and Canada (Blizzard) Not considered as a major exploration target in other countries.Should exist in other part of the world where valleys incized in U-rich granites,filled with organic matter bearing silicicalstic sediments, covered by basalts Interesting features : • Close to the surface • Amenable by in situ leaching • Average size and grades
  • 13. 9.2. Tabular U disseminated within reduced sediments along lenticular shaped massesoriented parallel to the stratigraphy Individual deposits: x100 t U up to 150,000 t U, @ 0.05 - 0.5% (up to 1%) 3 sub-types :Continental fluvial, U associated with intrinsic reductant Arlit type, NigerContinental fluvial, U associated with extrinsic humate/bitumen Grants type, USAContinental fluvial vanadium-uranium Salt Wash type, USA
  • 14. 9.2. TabularContinental fluvial, U associated with intrinsic reductant Tabular to lenticular U ore bodies hosted in arkoses rich in detrital C-matter incontinental fluvial channel systems, interbedded with claystone-shale beds. U ± Zn, Cu, V, Mo, Zr: pitchblende & coffinite disseminated in reduced, pyriticsandstone and as finely disseminated argillic-organic U complexes Resources are small to large (< 100 to 150 000 t) @ 0.10 to 0.50%Ex. : Arlit District (Niger) with total resources exceeding 600 000 t.
  • 15. 9.2. TabularContinental fluvial, U associated with extrinsic humate/bitumenU associated with humate/bitumen Mineralization disseminated in lenses within continental sandstone intercalatedwith shale Sandstone represents 60-80% of the volume and but pyroclastics are common The host sandstone was deposited in a mid-fan environment within an extensivefluvial-lacustrine sedimentary systemResources are medium to large (500-35,000 t @ 0.10-0.40%) Ex.: Ambrosia Lake District (USA) with resources in the order of 130 000 t U
  • 16. 9.2. TabularContinental fluvial, U associated with extrinsic humate/bitumen The primary ore (reduced ore which has undergone little alteration since its formation during early diagenesis) = fine-grained mixture of urano-organic complexes : = cryptocrystalline colfinite + amorphous organic matter that commonly fills primary pores Amorphous organic matter highly aromatic: high O/C ratio: 0.2 - 0.3 originated as humic acids derived from plant material  However, irradiation of organic matter (OM) leads to its oxidation Are the O/C ratios determined during the 80’s those of the pristineOM or do they correspond to modified migrated OM from marine origin ?
  • 17. 9.2. TabularContinental fluvial vanadium-uranium U associated with V in reduced fluvial sandstone within a sequence ofcontinental red-bed sediments. The sedimentary succession comprises: * thin, widespread units of reduced sandstone * with interbeds of grey clay and carbonaceous debris U ore is largely epigenetic, but syngenetic uranium enrichment may have existedDeposits are small to medium (1-2 000 t U) @ 0.05-0.50% UHigh vanadium content often increases their economic viability Ex : Salt Wash uranium district, USA
  • 18. IAEA classification 20129. Sandstone9.1. Basal channel(Dalmatovskoye, Russian Federation; Beverley, Australia)9.2. TabularContinental fluvial, U associated with intrinsic reductant (Arlit type, Niger)Continental fluvial, U associated with extrinsic humate/bitumen (Grants type, USA)Continental fluvial vanadium-uranium (Salt Wash type, USA)9.3. RollfrontContinental basin, U associated with intrinsic reductant (Wyoming type, USA)Continental to marginal marine, U associated with intrinsic reductant (Chu-Saryisu type, Kazhakstan)Marginal marine, U associated with extrinsic reductant (South Texas, USA)9.4. Tectonic-lithologic(Lodève Basin, France; Franceville Basin, Gabon)9.5. Mafic dykes/sills in Proterozoic sandstone(Westmoreland District, Australia; Matoush, Canada)
  • 19. 9.3. Rollfront mineralized zones are crescent shape, oriented down the hydrologic gradientdiffuse boundaries with reduced sandstone on the down-gradient side . …sharp contacts with oxidized sandstone on the up-gradient side elongated and sinuous mineralized zones approximately parallel to the strike, . . . perpendicular to the direction of deposition and groundwater flow Resources from x 100 to X 1,000 t U @ 0.05% to 0.25%Continental basin, U associated with intrinsic reductant Wyoming type, USAContinental to marginal marine, U associated with intrinsic reductant Chu-Saryisu type, KazhakstanMarginal marine, U associated with extrinsic reductant South Texas, USA
  • 20. 9.3. Rollfront U deposit genesisFormed where oxidized groundwater encounters reducing conditions in permeable sandstone U in solution is precipitated at the redox interface, forming a crescent- shaped roll-front ore body The roll front crosscut the sandstone bedding The reduction front migrates gradually in the direction of groundwater flow, creating the ore body with progressive U-accumulation
  • 21. Se U, V MoZonality with Se behindthe front and Mo beyond U and V
  • 22. 9.3. RollfrontContinental basin, U associated with intrinsic reductant U occurs disseminated at the redox boundary at the contact with pyrite-bearingsandstone and detrital carbonaceous debris on the down-gradient side in arkosicand subarkosic sandstones deposited in intracratonic or intermontane basins These basins are in spatial proximity with proximal to rocks (such as granites,and tuffs) containing anomalous uranium concentrations Most deposits occur within interbedded sequences of fluvial sandstones andvolcanic-rich sediments The shapes of deposits is strongly controlled by the permeability of the hostrocksResources are small to large (100-1 000 t U @ 0.05-0.20%)Ex.: Wyoming basins with resources of 250 000 t.
  • 23. 9.3. RollfrontContinental to marginal marine, U associated with intrinsic reductant Deposits are similar to roll front deposits in continental basins, but hostlithologies correspond to a sequence of mixed continental and marginal marineorigin. Resources are medium to large (1 000-100 000 t U @ 0.04-0.08% U)The World’s largest resources of this type (> 800 000 t) are located in the Chu-Sarysuand Syr-Daria Basins (South Kazakhstan).
  • 24. Evolution of Kazak Uranium Production 19.450 t U 35% World P.
  • 25. 9.3. RollfrontMarginal marine, U associated with extrinsic reductant U is concentrated in roll-type deposits near faults and in contact with pyrite /marcasite-bearing sandstone on their downgradient side Hosts environment include point bars, lateral bars and crevasse splaysdeposited in a fluvial environment and barrier bars and offshore bars in a marineenvironment Deposits are small to medium (50-5 000 t U @ < 0.05-0.25% U)Ex.: South Texas Uranium region : resources of 100 000 t U
  • 26. Oxygenated meteoric ground waters Adams and Smith, 1981 limb Extend of upward roll front gas migration Reduced sandstone Reduced gas mi sandstone gra t ion Primary oxidized sandstone(iii) fault controlled influx of reducing compounds Extend of downward (South Texas) H2S gas migration Hydrocarbons
  • 27. IAEA classification 20129. Sandstone9.1. Basal channel(Dalmatovskoye, Russian Federation; Beverley, Australia)9.2. TabularContinental fluvial, U associated with intrinsic reductant (Arlit type, Niger)Continental fluvial, U associated with extrinsic humate/bitumen (Grants type, USA)Continental fluvial vanadium-uranium (Salt Wash type, USA)9.3. RollfrontContinental basin, U associated with intrinsic reductant (Wyoming type, USA)Continental to marginal marine, U associated with intrinsic reductant (Chu-Saryisu type, Kazhakstan)Marginal marine, U associated with extrinsic reductant (South Texas, USA)9.4. Tectonic-lithologic(Lodève Basin, France; Franceville Basin, Gabon)9.5. Mafic dykes/sills in Proterozoic sandstone(Westmoreland District, Australia; Matoush, Canada)
  • 28. 9.4. Tectonic-lithologicdiscordant to concordant to strata. Occur in permeable fault zones and adjacent sandstone beds in reducingenvironments created by hydrocarbons and/or detrital organic matterUranium is precipitated in open fracture or fault zones related to tectonicextension.Individual deposits contain a x 100 mt U up to 5 000 mt U @ 0.1%- to 0.5%.Ex. : Lodève District (France) and the Franceville Basin (Gabon).
  • 29. 9.4. Tectonic-lithologicGeological cross-section of the north border of the Lodève Permian Basin (FRANCE)The U mineralization is associated to the main fault systems (from Mathis et al. 1990)
  • 30. IAEA classification 20129. Sandstone9.1. Basal channel(Dalmatovskoye, Russian Federation; Beverley, Australia)9.2. TabularContinental fluvial, U associated with intrinsic reductant (Arlit type, Niger)Continental fluvial, U associated with extrinsic humate/bitumen (Grants type, USA)Continental fluvial vanadium-uranium (Salt Wash type, USA)9.3. RollfrontContinental basin, U associated with intrinsic reductant (Wyoming type, USA)Continental to marginal marine, U associated with intrinsic reductant (Chu-Saryisu type, Kazhakstan)Marginal marine, U associated with extrinsic reductant (South Texas, USA)9.4. Tectonic-lithologic(Lodève Basin, France; Franceville Basin, Gabon)9.5. Mafic dykes/sills in Proterozoic sandstone(Westmoreland District, Australia; Matoush, Canada)
  • 31. 9.5. Mafic dykes/sills in Proterozoic sandstonemineralization is associated with mafic dykes and sills that are interlayered withor crosscut Proterozoic sandstone formations Deposits can be subvertical along the dyke’s borders, sometime within the dykes,or stratabound within the sandstones along lithological contacts (WestmorelandDistrict, Australia; Matoush, Canada).Deposits are small to medium (300-10 000 t U @ 0.05-0.40% U)Ex.: Westmoreland District, Australia; Matoush, Canada
  • 32. 9.5. Mafic dykes/sills in Proterozoic sandstone Type 1 Type 2 Mafic volcanics sandstone Type 3 Type 4 Mafic Volcanics Felsic Volcanics Unconformity Proterozoic sandstone Uranium mineralization 0 40 m Geological setting and types of mineral occurrences in the Westmoreland U field
  • 33. Relationships between sandstoneuranium deposits & fluids derived from hydrocarbon reservoirs
  • 34. Sandstone Uranium Deposits & Hydrocarbon ReservoirsSouth Texas Costal plains (Adams and Smith, 1981)Ordos, Song-Liao and Tarim basins (China) Hydrocarbons are reductants in organic-poor sandstonehosted U depositsIn Kazakhstan a spatial association between  HC-bearing reservoirs and overlying sandstone U deposits  HCs and/or H2S from HC-reservoirs migrated alongstructures and could have represented the reductants for Udeposition Franceville Basin (Gabon)
  • 35. Characterisationof uranium sources in sandstones (magmatic inclusions)
  • 36. U SOURCES (i) Outcropping uranium rich granites: Typically high K-calc-alkaline, peraluminous leucogranites (ii) Alteration of interbedded volcanic ash or tuff Typically high-K calcalkaline to peralkaline magmasPeralkaline magmas typically marked by high Zr content in the U-oxides (Niger ; Muhlenbach, Germany …) Characterisation of the volcanic source by magmatic inclusion study
  • 37. TECTONO-LITHOLOGIC (Akouta, Niger)
  • 38. AIR MASSIF
  • 39. Th vs. U volcanics rocksof Niger (Aïr, Zinder)and Nigeria
  • 40. Importance of the uranium derived froma synsedimentary volcaniclastic contribution for uranium deposits hosted in sandstone
  • 41. ANALCIME
  • 42. Rhyolite pebble Volcanic shards Evidences of a volcanic contribution melt in sedimentsinclusion
  • 43. meltinclusions
  • 44. MAGMATIC INCLUSIONSOFFER THE POSSIBILITY TO QUANTIFY THE INITIAL METAL and VOLATIL CONTENT OF THE MAGMAS : In volcanics (ex. Streltsovka, Russie and others) In plutonites (more difficult, because less well preserved) In sediments havinga volcanic componant Melt inclusion
  • 45. METHODOLOGY FOR ESTIMATION OF THE U POTENTIAL OF VOLCANIC ROCKSAnalyse of altered whole rocks : ICP-AES et MS Sélection of the inclusions and homogeneization at high temperature Analyse of the magmatic inclusions : - electronmicroprobe : major elts - ionic microprobe IMS3f : traces Massbalnce calculation between whole rocks / melt inclusions Évaluation of the quantity of mtals and et volatils loss / volume of rock
  • 46. Melt inclusion geochemistry from sandstone quartz grains
  • 47. Comparison melt inclusion composition from sandstone & Air rhyolites Air rhyolite field
  • 48. Melt inclusion geochemistry from sandstone (Shand diagr.) Al/(Na+K+2Ca)
  • 49. Th - U geochemistry of magmatic inclusion from sandstone 20
  • 50. Recent eruptions at the Yellowstone caldera (64 x 40 km) The biggest occurred at 2.1 Ma  Huckleberry Ridge ash bedThe 3rd largestat Long Valleyin Californiaproduced the Bishop ash bed. Credit: USGS
  • 51. EVOLUTION of U-GEOCHEMISTRY DURING EARTH HISTORY 4 0.45 Ga to presentMiddle Silurian  land plant apparition  reduced terrestrial clastic sediments U trapping in porous organic matter bearing continental sandstone Intraformational sandstone hosted deposits : - Tabular - roll front - tectonolithologic ... but when the reductant corresponds to migrated fluids deriving from deep seated oil reservoir trapped in permeable continetal sandstone  the deposits can be older than Silurian Ex. : - Oklo deposits - U-rich arkosic sandstone representing the source of most anatectic pegmatoids of Rössing type (metamorphosed equivalent of Oklo)
  • 52. U DEPOSITS FROM THE FRANCEVILLE BASIN: TYPICAL EXAMPLES OFPRE-SILURIAN SANDSTONE HOSTED U-DEPOSIT RELATED TO REDUCED FLUID MIGRATION FROM AN OIL PRODUCING FORMATION
  • 53. Franceville Basin GABON GABON Cameroun Lastourville2 Gabon Basin Guinée MASSIF DU Chaillu Og o Libreville HAUT-GABON Congo Massif ou é Mole0 Boyindzi d’Ondili Mounana Lastourville Oklo N Og oo ué OCE rz Okélobondo Franceville 10 km AN MASSIF DU Mabinga2 CHAILLU Bangombé Séries du Francevillien A Congo rz T Mikouloungou L A Formation FA > 500 m N Moanda T IQ Socle archéen U E 0 100 km Failles majeures Franceville 10 12 14 Gisements d’Uranium rz Zones de réaction Villes principales
  • 54. FE à Stratigraphic succession FC From Weber (1968) FB2 Mn-rich layers Dolomitic layers Pelites FB1 U Mineralization Coarse grained with FA Sandstone Mnz et Zrn1000 m Basal conglomerate Archean basement
  • 55. Oklo - Okélobondo Couche C1 Zones deW minˇralisˇe rˇaction E 15 Oklo carri¸re 1-2 3-6 7-9 Ampˇlites FB Gr¸s FB 13 10-16 OK84bis Okˇlobondo mine Socle100 m Gr¸s FA cristallin
  • 56. Pétrographie minéralisations dans le grès Ca Qzd QzdEch. OBD.96-9c : Ech. OBD.96-23 : Okélobondo MO minéralisée U-Pb-S Okélobondo
  • 57. M Fracture N-So FB pelites Redox fron td Fluide Hydrocarboné U mineralisatione Evaporitic layers FA carbonates F1l Fine grained non- Coarse silicified F4 Silicified FA FA sandstone Silicification - F3 Zr-P-Pb-TR-UVI F2 Diagenetic brine expulsed duringUVI erate compaction nglom sal co UVI FA Ba UVI Recharge Météorique Basement “chaude” et peu salée
  • 58. U-enrichment in metamorphosed epicontinental platform sediments Archean: Litsk area, NE Kola Peninsula, Russia, U pegmatoids “Hudsonian” S.L. : Wollaston and Mudjatik synsedimentary U enrichment : in meta-arkoses (Duddridge Lake), calcsilicates (Burbridge Lake & Cup Lake) in pegmatoids (Charlebois alaskites). Steward Lake, Québec, Canada Northern Québec, Ungava Bay and Baffin Island, U-pegmatoids : Lake Harbour Litsk district, Kola Peninsula, Russia, U pegmatoids, Wheeler Basin, Colorado: U- pegmatoids Orrefjell, Norway: U-pegmatoids Southern Finland : Late orogenic potassic granites Crocker Well, Olary Province, Flinders Range, South Australia Six Kangaroos area of Cloncurry-Mt. Isa District, Australia Nanambu, Nimbuwah, and Rum Jungle complexes, Katherine-Darwin area, Australia “Grenvillian” S.L. Occurrences : Bancroft, Ontario : 4 mines (5,700 t U produced),Mt Laurier, Johan Beetz, Havre St Pierre, Sept Iles, Port Cartier, St Augustin, Québec“Pan-African” Occurrences : Rössing, SH, Rössing South, Valencia , Ida, Goanikontes,
  • 59. LOOKING FORWARDMajor avenues for research & exploration for sandstone U deposits (1) : Sandstone related deposits represent more than 1/3rd of world U deposits andconsiderable resources are still wating to be discovered in many parts of the world In the new UDEPO data base new types of sandstone related U deposits havebeen introduced to account to their diversity Transitions exists between some synsedimentary uranium deposits, tabularsandstone type models, unconformity related model and some metamorphicuranium deposits (Katanga).The role of oil reservoir fluids (brines and associated marine hydrocarbons)migrated through faults into sandstone reservoirs as a major reductant forsandstone hosted U deposits:  change the exploration strategy:  looking for oil traps at the scale of the sedimentary basins  change in the distribution of oxidized vs reduced zones for roll fronts  open permeable pre-Silurian siliclastic formations for exploration
  • 60. LOOKING FORWARDMajor avenues for research & exploration for sandstone U deposits (2) : Looking more systematically for volcanic U contribution in continentalsandstones by magmatic inclusion studies  improve the quality of the U sourceAustralia is the first U province of the world but presents a huge deficit ofsandstone related U deposits:  large potential for further discoveriesVitim-type paleovalleys largely underexplored worldwide (except Russia, Mongolia) Sustainable development of sandstone U deposits by the recovery of associatedrare elements (rhenium, REE, … )