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The Geochemistry of Uranium Through Geological Time and the Evolution of Uranium Deposits By Mostafa Fayek Department of Geological Sciences University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

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Page 1: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

The Geochemistry of Uranium

Through Geological Time and the

Evolution of Uranium Deposits

By

Mostafa Fayek

Department of Geological Sciences

University of Manitoba

Workshop

Mendoza, Argentina

April 11-15, 2016

Page 2: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Genesis of Uranium Deposits

Factors influencing solubility of uranium:

1. Temperature

2. Redox (fO2)

3. pH

4. Activity of complexing anions

5. Partial pressure of volatiles (e.g. CO2)

6. Microbial activity

UO2

U4O9

U3O8

UO2F3-

UO2SO4o

UF22+

Fe2O3

FeCO3

Fe2+

FeS2

Bn

Cpy

Ksp

Serc/

Chl

KaolAlunUO6

Ka

ol

Modified from Romberger (1984)

Uraninite (UO2)

Uranophane Torbernite

Common oxidation states 4+ and 6+

Page 3: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

15 main types of deposits and 38 subtypes

1. Intrusive

2. Granite-related

3. Polymetallic hematite breccia complex (IOCG)

4. Volcanic-related

5. Metasomatite

6. Metamorphite

7. Proterozoic unconformity

8. Collapse breccia pipe

9. Sandstone

10. Paleo-quartz pebble conglomerate

11. Surficial

12. Coal-lignite

13. Carbonate

14. Phosphate

15. Black shales

Approximately 75% of the world’s U

reserve comes from 5 principal types of U

deposits

IAEA 2013 Classification

(Fayek, 2013)

Page 4: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

The type of uranium deposit-varied through time

CONTINENTAL

CRUST

1.7 ppm U

Alaskites

Vein

IOCG (U)

Volcanic

MANTLE

Upper continental

crust2.7 ppm U

Primitive mantle: 21 ppb

Carb. Chondrites: 7 ppb

Calcretes/Lignite/Coal

Conglomerates

Phosphates

Black shalesRollfront

Tabular

Tectonolitho

Breccia pipes

Unconformity

LT-Metamor

HT-Metamorphic

Na-Metasom

Magmatic

SEDIMENTARY

ROCKSIGNEOUS

ROCKS

METAMORPHIC

ROCKS

Basal channelA

BC

T(°C)

(A) alteration, erosion, transport, deposition, (B) diagenesis, metamorphism, and

(C) partial melting, crystal fractionation. Modified from Cuney (2009).

Page 5: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Geochronology of Uranium Deposits

Why is geochronology of uranium deposits important?

Source Transport Mechanism

Geological Environment

or

Depositional Mechanism

Timing

Page 6: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Cuney (2009, 2010)

4.55 to 3.1 Ga

3.1 to 2.2 Ga

2.2 to 0.45 Ga

0.45 to present

Hadean Archean Proterozoic Paleozoic

4.55 Ga 3.1 2.2 0.45

1 2 3 4

4 Major Periods of U Geochemistry Evolution:

Uranium Deposits Through Time

Page 7: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Uranium Deposits Through Time

1.Hadean-Paleoarchean (4.55 to 3.1 Ga)

• Thin mafic crust, U few ppm

• U4+ oxidation state in magmas and in aqueous fluids.

• U was in accessory minerals such as zircon

• No free oxygen (anoxic atmosphere)

Abbott et al. (2012)

No Uranium Deposits

Valley et al. (2014)

4.374 Ma

Page 8: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Uranium Deposits Through Time

2. Mesoarchean to Paleoproterozoic (3.1 to 2.2 Ga)

• Subduction and recycling of U-Th rocks

• First granites at ~3.1 to 2.8 Ga

• Peraluminous granites at 2.6 Ga (e.g., Tanco suite)

• Atmospheric rise of oxygen at ~2.5-2.2 Ga

• Uraninite in highly fractionated granites and pegmatites

Placer Uranium Deposits(Witwatersrand, Elliot Lake)

Cuney (2009, 2010)

Page 9: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

27°E

27°S 27°S

27°E0 50 100km

N

Central Rand Group

West Rand Group

Dominion Group

Archean granitoid

Greenstone

Witw

ate

rsra

nd

Superg

roupMajor fault

U-Au deposit

Vredefor

t

Johannesburg

Modified from Frimmel (2005)

Witwatersrand Basin

Sediments 2740 Ma

Uraniferous minerals 3050±50 Ma

and 2050±100 Ma

Meteorite impact at 2050 Ma

Rundle & Snelling (1977)

Page 10: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Huron Claim, MB

Sharpe and Fayek (2011)

Huron

ON

Age of host pegmatite- 2640±7 Ma

Age of uraninite- 2575±38 Ma

Resetting event (Rb-Sr) muscovite-2580±8 Ma

Page 11: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Uranium Deposits Through Time

3. Proterozoic to early Paleozoic (2.2 to 0.45 Ga)

• High pO2 atmosphere and pH hydrosphere

• Oxidation of detrital uraninite

• Uranyl species in solution (e.g., [UO2]2+)

• Increase in organic-rich sediments, phosphorite

• First redox controlled U deposits

• Genesis of large uranium provinces

Many Different Types of Uranium Deposits(Unconformity, Skarns, Metasomatite, IOCG)

Cuney (2009, 2010)

Page 12: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Oklo Uranium Deposits

Main ore- uraninite (UO2)

Tabular-sandstone deposits

Age- 2 billion years old

Uraninite achieved criticality 1.95 billion years

ago

Chemistry of uranium ore resembles the

chemistry of spent nuclear fuel

Ore temperatures over 1000oC for over

100,000 years

Page 13: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

3

6

9

3.0 2.25 1.5 0.75 0

0

3.68 % Oklo

Unconformity

0.7254 %

23

5U

/23

8U

x 1

00

Time (Ga)

0 100 m

W E

Black Shale (FB)

Sandstone (FA)

OKLO open pit151-2

3-67-9

13

10-16

Okelobondo

Archean Basement

FB Sandstones

U-rich Layer

Reactor Zones

Faults

Black Shale (FB)

Okelobondo

Sandstone (FA)

10-16

13

100 m0

Archean Basement

Faults

(modified from Gauthier-Lafaye et al., 1996)

Oklo Natural

Fission Reactors

•First redox controlled deposit

•Age: 2050 Ma

•Criticality: 1950 Ma

Page 14: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Athabasca Basin Uranium Deposits

Rabbit Lake, Athabasca Basin, CA

Uranium ore- uraninite (UO2)

Age = ~1.6 billion years old

Unconformity-related hydrothermal deposits

Over a billion pounds of uranium

World’s richest uranium deposits

Provides 18% of worlds uranium

Page 15: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Uranium Deposits Through Time

4. Paleozoic (0.45 Ga to present day)

• Land plants

• Organic-rich sediments (reduced clastic sediments)

• Organic matter uranium traps

• Microbial activity

Most Hydrothermal-Volcanic Uranium Deposits

Sandstone hosted Deposits (roll-front)

Near Surface Deposits (calcrete, bogs)

(Some of these deposits may not have been preserved in older rocks)

Cuney (2009, 2010)

Page 16: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Tabular deposits

Colorado, USA

Sandstone Uranium Deposits

Roll-front deposits

Colorado, USA

oxidized

Reduced

Page 17: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

0

0.05

0.10

0.15

0.20

0.25

0 21 3

207Pb/235U

206P

b/2

38U

A- 1362±11 Ma

293±16 Ma

(MSWD: 6.4)

B- 1287±16 Ma

136±116 Ma

C- 959±31 Ma

AB

C

1200 Ma

800 Ma

400 Ma

(2s errors)

(Cumming and Krstic, 1992)

Cigar Lake

100 mm

uraninite

coffinite

Ca-U-Oxy

•Simple matrix: UO2

•Complex mineralogy

Geochronology of Uranium Minerals

Page 18: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

uraninite

coffinite

Ca-U-Oxy

75 mm

In Situ Isotopic Analytical

Technique Required

Uraninite

500 mm

Athabasca Basin

Sue Zone

Page 19: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Secondary Ion Mass Spectrometry (SIMS)

Sample block

1 cm

100 mm

Page 20: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

The Athabasca Basin

Uranium Deposits

• The geology/structures-

sandstone and basement

hosted-Proterozoic basins

• Large alteration haloes

• Mineralogy: UO2 and coffinite,

low Th/U-hydrothermal

• Redox system: oxidizing and

reducing fluids, pH ~6

• Temperature: 250 oC, Depth: 5

km

• Timing/Geochronology: 1600

Ma-300 Ma

• Knowledge Gap:

• Age of mineralization

• Source of U

Page 21: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

•Two Fluids

•Polymetallic (Ni, Co,

As. Cu)

•High total REEs

•HREEs/LREEs ~1

•Single fluid

•Mono metallic

•Low total REEs

•HREEs/LREEs >1

(Jefferson et al., 2007)

Page 22: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Genesis of the Athabasca Uranium Deposits

0 100 m

Clay

alteration

Surface

Athabasca

Group

Aphebian

Metasediments

Fault

Unconformity

(modified from Marlatt et al., 1992)

Uraninite

Basment fluids

200 oC

Basin fluids

200 oC

1500, 1400, 1300, 900 MaBrine 200 oC

1477 Ma900 Ma250 oC

1590 Ma,1380Ma,

1280 Ma, 900 Ma,

500 Ma, 300 Ma

Illite

Quartz cements

Illite

Chlorite

Uraninite

500 mm (Alexander et al. 2009; Cloutier et al. 2010)

Page 23: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

U1

U11495 ± 26 Ma

U3

U3

1088 ± 22 Ma

U4 855 ± 27 Ma

The Athabasca Uranium Deposits

(Sheahan et al. 2016)

Kianna Deposit, W Athabasca

Page 24: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

1227 Ma

856 Ma

1002 Ma

Coffinite

Uraninite

75 mm 100 mm

Uraninite

The Athabasca Uranium Deposits

Errors ± 15 MaCigar Lake, E Athabasca

(Fayek et al. 2002)

Page 25: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

The Athabasca Uranium Deposits U-Pb Ages

Fluid events: 1550 Ma, 900 Ma

0

0.1

0.2

0.3

0.4

0 2 4 6

400

800

1200

1600

2000

960+66 Ma70+23 Ma

(MSWD 2.9)

(e)

20

6P

b/2

38U

207Pb/235U

313+11 Ma

0 2 3 4

207Pb/235U

2000

1600

1200

800

400

207Pb/235U

0

0.1

0.2

0.3

0.4

0 2 4 6

400

800

1200

1600

2000

1543+8 Ma508+13 Ma

(MSWD 1.4)

(a)

20

6P

b/2

38U

0.1

0.2

0.3

0.4

0 2 3 4

0

206P

b/2

38U

2000

1600

1200

800

400

Page 26: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Oklo Uranium Deposits

Main ore- uraninite (UO2)

Tabular-sandstone deposits

Age- 2 billion years old

Uraninite achieved criticality 1.95 billion years

ago

Chemistry of uranium ore resembles the

chemistry of spent nuclear fuel

Ore temperatures over 1000oC for over

100,000 years

Page 27: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

0 100 m

W E

Sandstone (FA)

Oklo open pit151-2

3-67-9

13

10-16

Okelobondo

FB Sandstones

U-rich Layer

Reactor Zones

Okelobondo

Sandstone (FA)

13

100 m0

(modified from Gauthier-Lafaye et al., 1996)

Archean Basement

Black Shale (FB)

Fault

The Oklo-Okélobondo Fission Reactors

Page 28: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Genesis of the Oklo-Okélobondo

Natural Fission Reactors

0 100 m

Sandstone (FA)

Archean

Basement

Uraniferous Fluid

~140 oC

Fault

Uranium Deposits

Clay Alteration

(modified from Gauthier-Lafaye and Weber, 1989)

Hydrocarbon Migration 140 oC

Black Shales (FB)

•Clays: 2036 Ma

•Fission: 1968 Ma

•Diagenesis:

1450 Ma, 860 Ma

•Dike: 850 Ma

•Uraninite: 2050 Ma, 2018 Ma,1780 Ma, 1500 Ma, 850 Ma, 755 Ma, 265 Ma, 68 Ma

Page 29: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

The Oklo-Okélobondo Fission Reactors

U-Pb Ages

dike emplacement

898±46 Ma

(RZ 10, OKE)

1945±50 Ma

570±48 Ma

criticality event

(RZ 2, 9, 13)

206P

b/2

38U

0.1

0.2

0.3

0.4

0

207Pb/235U

0 2 3 4

2000

1600

1200

800

400

2000

1600

1200

800

400

207Pb/235U

0 2 3 4

Page 30: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Athabasca Deposits

0

1

2

3

4

5

6

7

8

9

0 500 1000 1500 2000 2500

Age (Ma)

No. of

Anal

yse

s

Pinwarian

(~1.5 Ga)

Ryholites & granites

(1.45 Ga)

Age of

U deposits

(~1.55 Ga)

Post-Pin:

dike swarm

(~1.4-1.2 Ga)

Grenvillian

dike swarm (1.0 Ga)

(~1.3-1.0 Ga)

Rhodinia

Rifting:

(~0.9-0.7 Ga)

Pangea

(~300 Ma)

Oklo-Okélobondo

Fission Reactors

0

1

2

3

4

5

6

0 500 1000 1500 2000 2500

Age (Ma)

No. of

Anal

yse

s

Accretion:

Atlantica

(~2 Ga)Pan-African

(~0.5 Ga)Pangea

(~300 Ma)

Benue Rift

(~100-40 Ma)

Criticality

(~1.95 Ga)Age of

U Deposits

(~2.0 Ga)

Diagenesis

and Tanzinian

(~1.45-1.35 Ga)

Rhodinia

Rifting

(~0.9 Ga)

Rifting

(1.54Ga)

Page 31: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Tectonic Evolution of W. Africa

Rogers, 1996

Atlantica and deposition of seds ~2 Ga

Accretion of Tanzanian craton ~1.35 Ga

Rodinia 980-730 Ma

Pan African ~500 Ma

Lower Benue Rift ~100 Ma

Page 32: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Uranium Deposits

Oklo, Gabon

Lower Benue

Rift 100 Ma

Page 33: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Diffusion Model

For uranium minerals consisting of

multiple size domains, Pb will diffuse

faster from smaller domains relative to

larger domains.

D=m2/sec

Mark Escher

Page 34: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

phase A

10 nm

phase B

10 nm

Si

U

5 nm

phase B

Page 35: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

•Evolution of uranium deposits related to major

global events

•Ages correlate with tectonic and other geologic

events

•Large-scale events cause element migration-

geochronology of fluids

Conclusions

Page 36: The Geochemistry of Uranium Through Geological … Geochemistry of Uranium Through Geological Time and the ... University of Manitoba Workshop Mendoza, Argentina April 11-15, 2016

Acknowledgments

Prof. Kurt Kyser- Queen’s University

Prof. Alfredo Camacho- University of Manitoba

Prof. Rodney C. Ewing- Stanford University

Prof. Michel Cuney- Université de Lorraine

Canada Research Chairs

www.chairs-chaires.gc.ca