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Sandstone uranium deposits:Sandstone uranium deposits:Looking forwardLooking forward
Michel CUNEYMichel CUNEY
UMR G2R – CREGU – CNRSUMR G2R – CREGU – CNRSVandoeuvre les NANCYVandoeuvre les NANCY
FRANCEFRANCE
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PRESENTATION HIGHLIGHTS
To propose a general framework for the different types of uranium deposits associated with sandstone within the continuum of the geologic cycle
To try to go beyond the usual classifications using the recent work of the UDEPO group and more personal views
Such a general framework should help to set up the different contributions which will be presented during this meeting concerning deposits from all over the world
To trace the avenues for future research and exploration of sandstone related deposits
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IAEA classification 2012 1. Intrusive 2. Granite-related3. Polymetallic iron-oxide breccia complex4. Volcanic-related5. Metasomatite 6. 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 deposits 11. Surficial: 60 deposits 12. Lignite and coal 13. Carbonate14. Phosphate 15. Black shale
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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)
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A GENETIC CLASSIFICATION OF U-DEPOSITSA GENETIC CLASSIFICATION OF U-DEPOSITS Cuney, 2012 Cuney, 2012 1 – F1 – Fractional crystallizationractional crystallization
2 – 2 – Partial meltingPartial melting
3 3 – – Hydrothermal high level post-orogenic Hydrothermal high level post-orogenic :: 3A – Volcanic - hydrothermal3A – Volcanic - hydrothermal 3B – Granitic - hydrothermal3B – Granitic - hydrothermal
4 –4 – Diagenetic hydrothermal systems Diagenetic hydrothermal systems:: 4C: Intraformational redox control4C: Intraformational redox control
4C1: Tabular: Grants Mineral Belt, Beverley4C1: Tabular: Grants Mineral Belt, Beverley4C2: Tectonolithologic: Akouta, Niger4C2: Tectonolithologic: Akouta, Niger4C3 : Karsts (breccia pipes): Colorado4C3 : Karsts (breccia pipes): Colorado
4A: Basin/basement redox control (unconformity related)4A: Basin/basement redox control (unconformity related) 4B: Interformational redox control (Oklo Gabon) 4B: Interformational redox control (Oklo Gabon) but fluids similar to unconf. related Ubut fluids similar to unconf. related U
5 - Hydrothermal metamorphic 5 - Hydrothermal metamorphic (Katanga deposits transitional with diagenetic (Katanga deposits transitional with diagenetic hydrothermal systems)hydrothermal systems)
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6 – 6 – Hydrothermal metasomatic: Hydrothermal metasomatic: 6A – Alkali-metasomatism6A – Alkali-metasomatism 6B – Skarns :Mary Katheleen6B – Skarns :Mary Katheleen
7 – 7 – Syn-sedimentarySyn-sedimentary:: 7A: Mechanical sorting: Qz pebble conglomerates7A: Mechanical sorting: Qz pebble conglomerates 7B: Redox trapping: black shales7B: Redox trapping: black shales 7C: Crystal-chemical/redox trapping: phosphates7C: Crystal-chemical/redox trapping: phosphates
8 - Intraformational meteoric fluid infiltration8 - Intraformational meteoric fluid infiltration 8A:8A: Sealed paleovalleys: Vitim (Transbaikalia)Sealed paleovalleys: Vitim (Transbaikalia) 8B:8B: Roll fronts: Powder River Basin (Wyoming)Roll fronts: Powder River Basin (Wyoming)
9 –- 9 –- Weathering & evapotranspirationWeathering & evapotranspiration: calcretes: calcretes 10 – Other10 – Other types types
A GENETIC CLASSIFICATION OF U-DEPOSITS A GENETIC CLASSIFICATION OF U-DEPOSITS Cuney, 2012Cuney, 2012
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melting
MELTS / FLUIDS MANTLE
meltingSU
BDUC
TION
SURFACE WATERSMeteoric
DIAGENETICFLUIDS
Calcretes /Lignite/Coal
Black shales
RollfrontTabularTectonolithol.
Unconformity
-
Breccia Pipes
U deposits relatedto sedimentary
basins
SkarnsAlaskites
Crust PartialMelting
COLLISION
Volcanic
U deposits relatedto magmatic SURFACE WATERS
Meteoric
DIAGENETICFLUIDS
Metamorphicfluids
Calcretes /Lignite/Coal
Tabular
Unconformity
Metamorphic H.T.
Na-metasomatism
Breccia Pipes
Metamorphic L.T.
Silicatemelts
SkarnsAlaskitesCrust partial
COLLISION
to magmatic
Crustal
MA
GM
ATI
C F
RA
CTI
ON
ATI
ON
METAMORPHISM
MAGMATICFLUIDS
-
EXTENSION
rocks
MAGMATICFLUIDS
-
Magmatic-Hydrothermal
Fluids
rocks
Fract. cryst.
IOCG(U)
Veins
/Sea
Groundwaters
Formationwaters
/Sea
Groundwaters
Formationwaters
DIAGENESIS
EXHUMATION
PhosphatesConglomerates
FluidMIXING
to metamorphismmelting
Subductionfluids
Mantle
MIXINGU deposits related
GEOLOGIC CYCLE
Basal
Sandstone hosted
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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)
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9.1. Basal channel (Paleovalley): Vitim district, Russian Federation: RAR: 52,000 mt U, Speculative R.: 100,000 mt U
Geological map of the Khiagda ore field
8 deposits over 250km2 with 44,800mtU @ 0.05-0.3 %U, prognosticated R.: 60,000mt U, Khiagda: 15,500 mt U
Paleochannels with up to 50 m thick Oligocene-Miocene colluvial to alluvial grey to multicolored carbonaceous clay-siltstone, sandstone, conglomerate, intercalated lignite seams. Pyrite and plant debris, ~ 0.8% Corg
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9.1. Basal channelTypical cross-section through the Khiagda deposit.
granite
Neogene sediments (sand, silt, clay) grey oxidized reduced
U ore
basalt
90 m
60
30
0 0 60 km SW NE
Source: Highly potassic calcalkaline Hercynian granitesTransport: infiltrated meteoric fluids through permeable siliciclastic rocksDeposition: reduction by detrital organic matter (20 Ma to present)
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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)
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9.1. Basal channel looking forward
Model mainly discovered in Russia with some other minor occurrences in NW
Mongolia 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
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9.2. Tabular
U disseminated within reduced sediments along lenticular shaped masses oriented 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, Niger
Continental fluvial, U associated with extrinsic humate/bitumen
Grants type, USA
Continental fluvial vanadium-uranium
Salt Wash type, USA
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9.2. TabularContinental fluvial, U associated with intrinsic reductant
Tabular to lenticular U ore bodies hosted in arkoses rich in detrital C-matter in continental fluvial channel systems, interbedded with claystone-shale beds.
U ± Zn, Cu, V, Mo, Zr: pitchblende & coffinite disseminated in reduced, pyritic sandstone 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.
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9.2. Tabular
Continental fluvial, U associated with extrinsic humate/bitumen
U associated with humate/bitumen
Mineralization disseminated in lenses within continental sandstone intercalated with 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 extensive fluvial-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
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9.2. Tabular
Continental 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 - 0.3originated 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 ?
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9.2. TabularContinental fluvial vanadium-uranium
U associated with V in reduced fluvial sandstone within a sequence of continental 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% U High vanadium content often increases their economic viability
Ex : Salt Wash uranium district, USA
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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)
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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, USA
Continental to marginal marine, U associated with intrinsic reductant
Chu-Saryisu type, Kazhakstan
Marginal marine, U associated with extrinsic reductant
South Texas, USA
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9.3. Rollfront U deposit genesis
Formed 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
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Se U, V Mo
Zonality with Se behindthe front and Mo beyond U and V
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9.3. RollfrontContinental basin, U associated with intrinsic reductant
U occurs disseminated at the redox boundary at the contact with pyrite-bearing sandstone and detrital carbonaceous debris on the down-gradient side in arkosic and 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 and volcanic-rich sediments
The shapes of deposits is strongly controlled by the permeability of the host rocks
Resources are small to large (100-1 000 t U @ 0.05-0.20%)
Ex.: Wyoming basins with resources of 250 000 t.
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9.3. Rollfront
Continental to marginal marine, U associated with intrinsic reductant
Deposits are similar to roll front deposits in continental basins, but host lithologies correspond to a sequence of mixed continental and marginal marine origin.
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-Sarysu and Syr-Daria Basins (South Kazakhstan).
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Evolution of Kazak Uranium Production 19.450 t U
35% World P.
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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 splays deposited in a fluvial environment and barrier bars and offshore bars in a marine environment
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
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(iii) fault controlled influxof reducing compounds
(South Texas)
Reducedsandstone Reduced
sandstone
roll front
limbExtend ofupward
gas migration
gas migration
Extend ofdownward
gas migration
Oxygenated meteoric ground waters
H2SHydrocarbons
Adams and Smith, 1981
Primary oxidized
sandstone
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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)
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9.4. Tectonic-lithologic
discordant to concordant to strata.
Occur in permeable fault zones and adjacent sandstone beds in reducing environments created by hydrocarbons and/or detrital organic matter
Uranium is precipitated in open fracture or fault zones related to tectonic extension.
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).
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9.4. Tectonic-lithologic
Geological 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)
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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)
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9.5. Mafic dykes/sills in Proterozoic sandstone
mineralization is associated with mafic dykes and sills that are interlayered with or 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 (Westmoreland District, Australia; Matoush, Canada).
Deposits are small to medium (300-10 000 t U @ 0.05-0.40% U)
Ex.: Westmoreland District, Australia; Matoush, Canada
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9.5. Mafic dykes/sills in Proterozoic sandstone
Geological setting and types of mineral occurrences in the Westmoreland U field
Type 1 Type 2
Type 3 Type 4
Unconformity0 40 m
Mafic VolcanicsProterozoic sandstone
Felsic VolcanicsUranium mineralization
sandstone
Mafic volcanics
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Relationships between sandstone
uranium deposits & fluids derived
from hydrocarbon reservoirs
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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 sandstone hosted U deposits
In Kazakhstan a spatial association between HC-bearing reservoirs and overlying sandstone U deposits HCs and/or H2S from HC-reservoirs migrated along
structures and could have represented the reductants for U deposition
Franceville Basin (Gabon)
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Characterisation
of uranium sources in sandstones
(magmatic inclusions)
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U SOURCES
(i) Outcropping uranium rich granites: Typically high K-calc-alkaline, peraluminous leucogranites
(ii) Alteration of interbedded volcanic ash or tuffTypically high-K calcalkaline to peralkaline magmas
Peralkaline magmas typically marked by high Zr content in the U-oxides(Niger ; Muhlenbach, Germany …)
Characterisation of the volcanic source by magmatic inclusion study
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TECTONO-LITHOLOGIC (Akouta, Niger)TECTONO-LITHOLOGIC (Akouta, Niger)
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AIR MASSIF
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Th vs. U volcanics rocksof Niger (Aïr, Zinder)and Nigeria
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Importance of the uranium derived from
a synsedimentary volcaniclastic contribution
for uranium deposits hosted in sandstone
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ANALCIME
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Volcanic shards
meltinclusion
Rhyolitepebble
Evidences of a volcanic
contributionin sediments
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meltinclusions
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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 having a volcanic componant
Melt inclusion
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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
METHODOLOGY FOR ESTIMATION OF THE U POTENTIAL OF VOLCANIC ROCKS
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Melt inclusion geochemistry from sandstone quartz grains
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Comparison melt inclusion composition from sandstone & Air rhyolites
Air rhyolitefield
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Melt inclusion geochemistry from sandstone (Shand diagr.)
Al/(Na+K+2Ca)
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20
Th - U geochemistry of magmatic inclusion from sandstone
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Recent eruptions at the Yellowstone caldera (64 x 40 km)
Credit: USGS
The biggest occurred at 2.1 Ma Huckleberry Ridge ash bed
The 3rd largest at Long Valley in California produced the Bishop ash bed.
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EVOLUTION of U-GEOCHEMISTRY DURING EARTH HISTORY 4
0.45 Ga to present
Middle Silurian land plant apparition reduced terrestrial clastic sediments
U trapping in porous organic matter bearing continental sandstoneIntraformational 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 SilurianEx. : - Oklo deposits - U-rich arkosic sandstone representing the source of most anatectic pegmatoids of Rössing type (metamorphosed equivalent of Oklo)
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U DEPOSITS FROM THE FRANCEVILLE BASIN:U DEPOSITS FROM THE FRANCEVILLE BASIN:
TYPICAL EXAMPLES OFTYPICAL EXAMPLES OF
PRE-SILURIAN SANDSTONE HOSTED U-DEPOSITPRE-SILURIAN SANDSTONE HOSTED U-DEPOSIT
RELATED TO REDUCED FLUID MIGRATIONRELATED TO REDUCED FLUID MIGRATION
FROM AN OIL PRODUCING FORMATIONFROM AN OIL PRODUCING FORMATION
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Ogooué
Chaillu Massif
LastourvilleBasin
Oklo Okélobondo
Mole d’Ondili
Franceville
10 km
Séries du FrancevillienFormation FA > 500 mSocle archéenFailles majeuresGisements d’Uranium
Bangombé
N
Mounana
Moanda
Mikouloungou
Villes principales
O C
E A
NA T L A N T I Q
U E
Cameroun
Guinée
Congo
Congo
Libreville
Ogooué
0 100 km
Lastourville
MASSIF DU HAUT-GABON
0
2
10 12 14
2Gabon
FrancevilleMASSIF DU
CHAILLU
Zones de réactionrz
Boyindzi
rz
rz
Franceville Basin GABON
Mabinga
GABON
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Stratigraphic successionStratigraphic successionStratigraphic successionStratigraphic succession
U
FA
FB1
FB2
FE àFC
1000 m
Archean basement
Sandstone
Pelites
Mineralization
Dolomitic layersMn-rich layers
Basal conglomerate
Coarse grained withMnz et Zrn
From Weber (1968)
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OOklo - klo - OOkélobondokélobondoOOklo - klo - OOkélobondokélobondo
100 m
W E
Okˇlobondo mine
Oklo carri¸re151-2
3-67-9
13
10-16
OK84bis
Gr¸s FA
Zones de rˇaction
Couche C1 minˇralisˇe
Gr¸s FB
Ampˇlites FB
Socle cristallin
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PPétrographie minéralisations dans le grèsétrographie minéralisations dans le grèsPPétrographie minéralisations dans le grèsétrographie minéralisations dans le grès
Ca
Qzd
MO minéralisée U-Pb-S
Qzd
Ech. OBD.96-9c : Okélobondo
Ech. OBD.96-23 : Okélobondo
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Model
RRecharge Météoriqueecharge Météorique ““chaude” et peu saléechaude” et peu salée
FFluide Hydrocarbonéluide Hydrocarboné
Basement
Coarse silicified FA sandstone
FB pelites
Fine grained non-Silicified FA
U mineralisation
UVI
F2
Silicification
Redox front
FractureN-S
F1
F3 -
F4
FA Basal conglomerateUVI
UVI
Evaporitic layers FA carbonates
Zr-P-Pb-TR-UVI
Diagenetic brineDiagenetic brineexpulsed during expulsed during
compactioncompaction
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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 HarbourLitsk district, Kola Peninsula, Russia, U pegmatoids,
Wheeler Basin, Colorado: U- pegmatoidsOrrefjell, 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,
U-enrichment in metamorphosed epicontinental platform sediments
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LOOKING FORWARDMajor avenues for research & exploration for sandstone U deposits (1) :
Sandstone related deposits represent more than 1/3rd of world U deposits and considerable 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 have been introduced to account to their diversity
Transitions exists between some synsedimentary uranium deposits, tabular sandstone type models, unconformity related model and some metamorphic uranium deposits (Katanga).
The role of oil reservoir fluids (brines and associated marine hydrocarbons) migrated through faults into sandstone reservoirs as a major reductant for sandstone 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 need to reasess the nature of the organic material in the humate type
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Major avenues for research & exploration for sandstone U deposits (2) :
Vitim-type paleovalleys largely underexplored worldwide (except Russia, Mongolia)
Sustainable development of sandstone U deposits by the recovery of associated rare elements (rhenium, REE, … )
LOOKING FORWARD
Looking more systematically for volcanic U contribution in continental sandstones 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 of sandstone related U deposits: large potential for further discoveries