The document discusses the application of geophysics in exploring for sandstone-hosted uranium deposits in Mongolia. Geophysical surveys were conducted at the Dundgovi 5 and Tamsag 1 project sites to understand basin morphology, near-surface geology, and identify structures and stratigraphy favorable for uranium mineralization. Regional gravity, magnetics, and seismic data helped target drilling, with seismic in particular providing details of the subsurface. Integration of geophysical data with drill results enhanced geological models at both sites.

1. The Application of Geophysics in Exploring for
Sandstone-Hosted Uranium in Mongolia
Garnet Wood1, Clinton Keller1, Orgil Bayarsaikhan 2
1Cameco Corporation, 2Cameco Mongolia
IAEA Conference: The Origin of Sandstone Hosted Uranium Deposits: A Global Perspective
VIC, Vienna, Austria: May 29 – June 1, 2012

2. Outline
● Geophysical survey objectives for sandstone uranium deposits
● Dundgovi and Tamsag projects
– Regional geology
– Regional and detailed geophysical results
● Conclusions
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3. Geophysical Survey Objectives
● Provide information that will assist in the understanding of the
morphology of Cretaceous basins in Mongolia, focusing
exploration and guiding timely land evaluation
● Provide detailed information on near surface geology that
assists in understanding of the structural and stratigraphic
settings at regional and prospect scales
● Guide drill hole targeting for environments favorable for
sandstone hosted uranium mineralization
● Enhance value derived from geophysical data through
continual integration with drill results
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4. Location Map
4

5. Mongolia – Regional Geology
5

6. Mongolia – Geological Map
6

7. Mongolia – Deposit Models
Roll Front
Structural
Tabular
Basal Channel
(Internal Cameco figure)
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8. Dundgovi 5 – Regional Geology
Khairhan Kharaat
Nars
Dulaan
Uul
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9. Dundgovi 5 – Location Map
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10. Mongolia – Stratigraphy
Stratigraphy Formation Member Lithology Description
KZ
(CENOZOIC)
Baruunbayan Mudstone member Primary Red Coloured Mud
K2
(UPPER Formation
CRETACEOUS) (Sainshand Sandstone
Reddish mud layers interbedded
Formation) with unconsolidated red sand. Mud
member
matrix
Siltstone member Grey coloured silt
Khukhteeg
Formation
(Upper part Siltstone/Sandstone Grey siltstone and sandstone
of Zuunbayan member interbedding. Siltstone dominated
K1 Formation) Gravel member
(LOWER Pebbles, gravels, conglomerates.
CRETACEOUS)
Shinekhudag
Formation Siltstone member Dark grey coloured carbonaceous
silt with clay interbedding
(Lower part
of Zuunbayan
Formation)
Gravel member Green-grey gravelly sand.
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11. Dundgovi 5 – Regional Gravity
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12. Dundgovi 5 – Regional Magnetics
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13. Dundgovi 5 – Regional Gravity
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14. Dundgovi 5 – Conceptual Target
Overburden (variable thickness)
Cretaceous
sandstone
0-
K2 horizon
Depth (m)
K1 horizon
500 - Basement
Basement faults
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15. Dundgovi 5 – Seismic Line 1
5 mGal
Magnetics
300 nT
Shot Point (km) Gravity
0 1.5 3.0 4.5 6.0 7.5 9.0 10.5 12.0 13.5
0.0
0.1
0.2
Two Way Traveltime (s)
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
VE = 5.5
1.1
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16. Dundgovi 5 – Seismic Line 1
5 mGal
Magnetics
300 nT
Shot Point (km) Gravity
0 1.5 3.0 4.5 6.0 7.5 9.0 10.5 12.0 13.5
0.0
0.1 Tertiary sediments DG5-001
0.2
Two Way Traveltime (s)
0.3 Cretaceous
0.4 stratigraphy
0.5
0.6
Basement rocks
0.7
0.8
0.9
1.0
VE = 5.5
1.1
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17. Drill Hole DG5-001
Shot Point (km)
11.22 11.34 11.46 11.58 11.70
● Sonic log (grey)
overlain on drill hole 150
trace of DG5-001
200
● Dashed line is
interpreted fault 250
targeted by DG5-001
Depth (m)
300
● Black line is interpreted K2
K2/K1 contact based 350
on drill core and sonic
400
log data K1
450
500
550
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18. Dundgovi 5 – Seismic Line 2
300 nT
Magnetics
5 mGal
Gravity
Shot Point (km)
0 1.5 3.0 4.5 6.0 7.5 9.0 10.5 12.0 13.5 15.0
0.0
0.1
0.2
Two Way Traveltime (s)
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
VE = 5.5
1.1
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19. Dundgovi 5 – Seismic Line 2
300 nT
Magnetics
5 mGal
Gravity
Shot Point (km)
0 1.5 3.0 4.5 6.0 7.5 9.0 10.5 12.0 13.5 15.0
0.0
0.1
0.2
Two Way Traveltime (s)
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
VE = 5.5
1.1
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20. Tamsag 1 – Location Map
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21. Tamsag 1 – Regional Geology
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22. Tamsag 1 – Regional Geophysics
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23. Tamsag 1 – Seismic Line 1
Magnetics
300 nT
3 mGal
Shot Point (km) Gravity
0 3.0 6.0 9.0 12.0 15.0 18.0 21.0 24.0 27.0 30.0
0.0
0.1
0.2
Two Way Traveltime (s)
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1 VE = 12
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24. Tamsag 1 – Seismic Line 1
Magnetics
300 nT
3 mGal
Shot Point (km) Gravity
0 3.0 6.0 9.0 12.0 15.0 18.0 21.0 24.0 27.0 30.0
0.0
0.1
0.2 Upper Cretaceous
Two Way Traveltime (s)
0.3
0.4
0.5 Lower Cretaceous
0.6
0.7
0.8
0.9
1.0
1.1 VE = 12
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25. Tamsag 1 – Seismic Line 1
Magnetics
300 nT
3 mGal
Shot Point (km) Gravity
0 3.0 6.0 9.0 12.0 15.0 18.0 21.0 24.0 27.0 30.0
0.0
MTK-001 MTK-002 MTK-003
0.1
0.2
Two Way Traveltime (s)
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1 VE = 12
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26. Conclusions
● Regional geophysical data (airborne magnetics and ground gravity)
is a valuable tool in understanding the regional architecture of
Cretaceous basins in Mongolia
● Seismic data has proven to be invaluable in detailing the structural
and stratigraphic settings within these basins
● Seismic data has provided the detail required for targeting in
geological environments thought to be prospective for sandstone
hosted uranium mineralization
● Drill hole information has added significantly to the understanding
and interpretability of the geophysical data
● Seismic data, coupled with drilling, has provided increased
confidence in land retention decisions
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