1 u deposits sandstones looking forward cuney

Sandstone uranium deposits:Sandstone uranium deposits:Looking forwardLooking forward

Michel CUNEYMichel CUNEY

UMR G2R – CREGU – CNRSUMR G2R – CREGU – CNRSVandoeuvre les NANCYVandoeuvre les NANCY

FRANCEFRANCE

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

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

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)

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)

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

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






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

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)






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

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

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.

9.2. Tabular


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

9.2. Tabular


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 ?

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






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

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

Se U, V Mo

Zonality with Se behindthe front and Mo beyond U and V

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.

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).

Evolution of Kazak Uranium Production 19.450 t U

35% World P.

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

(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






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).

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)






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

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

Relationships between sandstone

uranium deposits & fluids derived

from hydrocarbon reservoirs

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)

Characterisation

of uranium sources in sandstones

(magmatic inclusions)

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

TECTONO-LITHOLOGIC (Akouta, Niger)TECTONO-LITHOLOGIC (Akouta, Niger)

AIR MASSIF

Th vs. U volcanics rocksof Niger (Aïr, Zinder)and Nigeria

Importance of the uranium derived from

a synsedimentary volcaniclastic contribution

for uranium deposits hosted in sandstone

ANALCIME

Volcanic shards

meltinclusion

Rhyolitepebble

Evidences of a volcanic

contributionin sediments

meltinclusions

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

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

Melt inclusion geochemistry from sandstone quartz grains

Comparison melt inclusion composition from sandstone & Air rhyolites

Air rhyolitefield

Melt inclusion geochemistry from sandstone (Shand diagr.)

Al/(Na+K+2Ca)

20

Th - U geochemistry of magmatic inclusion from sandstone

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.

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)

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

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

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)

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

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

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

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

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

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

Documents

1 u deposits sandstones looking forward cuney