Austria conference 2012-Uranium Sandstone

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 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

3. IAEA classification 2012
1. Intrusive
2. Granite-related
3. Polymetallic iron-oxide breccia complex
4. Volcanic-related
5. Metasomatite
6. Metamorphite
7. Proterozoic unconformity: 82 deposits
8. Collapse-breccia pipe (Arizona Strip, USA)
9. Sandstone: 576 deposits from 1405 compiled in the UDEPO data base
10. Paleo-quartz-pebble conglomerate: 62 deposits
11. Surficial: 60 deposits
12. Lignite and coal
13. Carbonate
14. Phosphate
15. Black shale

4. IAEA classification 2012
9. Sandstone
9.1. Basal channel
(Dalmatovskoye, Russian Federation; Beverley, Australia)
9.2. Tabular
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)
9.3. Rollfront
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)
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
AT
MAGMATIC
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 2012
9. Sandstone
9.1. Basal channel
(Dalmatovskoye, Russian Federation; Beverley, Australia)
9.2. Tabular
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)
9.3. Rollfront
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)
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 U
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
Geological map of the Khiagda ore field

10. 9.1. Basal channel
Typical 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 2012
9. Sandstone
9.1. Basal channel
(Dalmatovskoye, Russian Federation; Beverley, Australia)
9.2. Tabular
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)
9.3. Rollfront
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)
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 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

13. 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

14. 9.2. Tabular
Continental 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.

15. 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

16. 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 - 0.3
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 pristine
OM or do they correspond to modified migrated OM from marine origin ?

17. 9.2. Tabular
Continental 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

18. IAEA classification 2012
9. Sandstone
9.1. Basal channel
(Dalmatovskoye, Russian Federation; Beverley, Australia)
9.2. Tabular
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)
9.3. Rollfront
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)
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, USA
Continental to marginal marine, U associated with intrinsic reductant
 Chu-Saryisu type, Kazhakstan
Marginal marine, U associated with extrinsic reductant
 South Texas, USA

20. 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

21. Se U, V Mo
Zonality with Se behind
the front and Mo beyond U and V

22. 9.3. Rollfront
Continental 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.

23. 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).

26. Evolution of Kazak Uranium Production
19.450 t U
35% World P.

27. 9.3. Rollfront
Marginal 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

28. 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

29. IAEA classification 2012
9. Sandstone
9.1. Basal channel
(Dalmatovskoye, Russian Federation; Beverley, Australia)
9.2. Tabular
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)
9.3. Rollfront
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)
9.4. Tectonic-lithologic
(Lodève Basin, France; Franceville Basin, Gabon)
9.5. Mafic dykes/sills in Proterozoic sandstone
(Westmoreland District, Australia; Matoush, Canada)

30. 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).

31. 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)

32. IAEA classification 2012
9. Sandstone
9.1. Basal channel
(Dalmatovskoye, Russian Federation; Beverley, Australia)
9.2. Tabular
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)
9.3. Rollfront
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)
9.4. Tectonic-lithologic
(Lodève Basin, France; Franceville Basin, Gabon)
9.5. Mafic dykes/sills in Proterozoic sandstone
(Westmoreland District, Australia; Matoush, Canada)

33. 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

34. 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

35. Relationships between sandstone
uranium deposits & fluids derived
from hydrocarbon reservoirs

36. 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)

42. Characterisation
of uranium sources in sandstones
(magmatic inclusions)

43. 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 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

44. TECTONO-LITHOLOGIC (Akouta, Niger)

45. AIR MASSIF

46. Th vs. U volcanics rocks
of Niger (Aïr, Zinder)
and Nigeria

47. Importance of the uranium derived from
a synsedimentary volcaniclastic contribution
for uranium deposits hosted in sandstone

48. ANALCIME

49. Rhyolite
pebble
Volcanic shards
Evidences of
a volcanic
contribution
melt in sediments
inclusion

50. melt
inclusions

51. MAGMATIC INCLUSIONS
OFFER 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

52. 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

53. Melt inclusion geochemistry from sandstone quartz grains

54. Comparison melt inclusion composition from sandstone & Air rhyolites
Air rhyolite
field

55. Melt inclusion geochemistry from sandstone (Shand diagr.)
Al/(Na+K+2Ca)

56. Th - U geochemistry of magmatic inclusion from sandstone
20

57. Recent eruptions at the Yellowstone caldera (64 x 40 km)
The biggest occurred at 2.1 Ma  Huckleberry Ridge ash bed
The 3rd largest
at Long Valley
in California
produced the Bishop ash bed. Credit: USGS

58. 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 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)

59. U DEPOSITS FROM THE FRANCEVILLE BASIN:
TYPICAL EXAMPLES OF
PRE-SILURIAN SANDSTONE HOSTED U-DEPOSIT
RELATED TO REDUCED FLUID MIGRATION
FROM AN OIL PRODUCING FORMATION

60. Franceville Basin GABON
GABON
Cameroun
Lastourville
2 Gabon Basin
Guinée
MASSIF DU
Chaillu Og
o
Libreville HAUT-GABON
Congo
Massif ou
é
Mole
0 Boyindzi d’Ondili
Mounana
Lastourville
Oklo
N
Og
oo
ué
OCE
rz
Okélobondo
Franceville 10 km
AN
MASSIF DU Mabinga
2 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

61. 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 Zrn
1000 m
Basal conglomerate
Archean basement

62. Oklo - Okélobondo
Couche C1 Zones de
W minˇralisˇe rˇaction E
15 Oklo carri¸re
1-2
3-6
7-9 Ampˇlites FB
Gr¸s FB
13
10-16
OK84bis
Okˇlobondo mine
Socle
100 m Gr¸s FA
cristallin

63. Pétrographie minéralisations dans le grès
Ca
Qzd
Qzd
Ech. OBD.96-9c : Ech. OBD.96-23 :
Okélobondo
MO minéralisée U-Pb-S Okélobondo

64. M Fracture
N-S
o FB pelites Redox fron
t
d Fluide Hydrocarboné U mineralisation
e Evaporitic layers
FA carbonates F1
l 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

65. 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,

66. LOOKING FORWARD
Major 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

67. LOOKING FORWARD
Major avenues for research & exploration for sandstone U deposits (2) :
 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
Vitim-type paleovalleys largely underexplored worldwide (except Russia, Mongolia)
 Sustainable development of sandstone U deposits by the recovery of associated
rare elements (rhenium, REE, … )