2. o
Actinide element
o
3 ppm average abundance
in crust
• Cu = 68 ppm
• Ni = 90 ppm
• Fe = 63,000 ppm
o
Mobile element
o
Uranium is a radioactive
element
◦ Unstable, must decay to
stable element
◦ Five times more radioactive
than thorium
o
Main use is fuel in nuclear
reactors (power)
Pitchblende (uraninite)
• Dominant ore mineral
2
3. o
85 natural occurring RA elements and isotopes exist
◦ Th-232, U-238, and K-40 are the most common
◦ Also cosmological RA → C-14, H-3 (Tritium)
Drum of yellowcake
o
RA is everywhere
◦ Its all relative and a matter of perception
◦ A banana is radioactive (K-40)
o
RA elements have an unstable nucleus
• Isotopes are atoms that have the same number
of protons but a different number of neutrons
• Elements may have many isotopes, each with
◦ 14 elements in uranium decay series
different properties
◦ (U-238 decays to stable Pb-206)
◦ Daughter products with short half-lives are problem
o
Yellowcake concentrate end-product
◦ Not RA as daughter products stripped away
◦ 70-90% U3O8, +UO2 and UO3
3
4. o
Three isotopes of uranium
◦ Abundance in nature = U-238 (99.27%), U-235 (0.72%), and U-234 (0.006%)
Nuclear Power Plant
• Requires enrichment to ~1-5% U-235
• Complex and difficult process
Weapons Grade
• Requires enrichment to +85% U-235
• Extremely complex and difficult process
• If one person’s power needs for their entire life were
satisfied by nuclear energy, the waste produced would fit
into a single pop can
4
5. o
Regulated Canadian allowed dosage is max 20 millisievert (mSv) per year
◦ Average Canadian receives 1.8 mSv per year (range up to 4.0 depending on
latitude)
◦ India, Brazil range from 20 to 50+ mSv per year with no ill effects ever reported
o
o
o
Uranium mine workers in Canada receive a dosage of ~1 to 5 mSv per year
RA exposure from uranium exploration and mining is well managed and
not hazardous to a workers health when set protocols are followed
Remember, RA is everywhere
◦ RA is source of heat and is critical to the earth as we know it
◦ Without it the Outer Core would be solid, the earth would cool, and plate
tectonics would not occur
*Dosage information source: D. Grant Feasby, COM2013 Presentation
5
6. o
o
o
Highest grade deposits are found in the
Athabasca Basin, Northern Saskatchewan,
Canada
Average world grade is
0.14 % U3O8
Average Basin grade is
2% U3O8
◦ Several deposits/mines with ore grade
over 15%
MacArthur River, Cigar Lake, Phoenix
o
Largely underexplored and low geopolitical risk
6
7. o For Athabasca Basin uranium deposits to form, they require:
1. URANIUM BEARING FLUIDS (U6+),
2. STRUCTURES to act as conduits for fluid flow,
3. GRAPHITIC CONDUCTORS (or other reductant) to
facilitate uranium deposition (U4+), and
4. TIME (millions of years)
o Two main end-member deposit types
o Unconformity-sandstone hosted
o E.g. Cigar Lake
o Basement hosted
o Patterson Lake South (PLS),
Roughrider, Millennium
7
8. o
o
Paleoproterozoic (1740 Ma)
Sedimentary Basin
Two main uranium
mineralizing events
◦ 1500 and 1350 Ma
◦ Further alteration and uranium remobilization at 1176, 900, and 300
Ma
Athabasca Basin
formation begins
8
10. Carswell Structure formed by meteorite impact @ ~115 Ma (Lower Cretaceous)
*From Jefferson et. al. 2007
10
11. o
o
Pitchblende first discovered in 1935
on north shore of Lake Athabasca,
now known as Beaverlodge District
Beaverlodge
District
Production from 1953 to 1982
◦ >60 million pounds (Mlbs) uranium
produced
◦ Production from 16 deposits, milled at 3
facilities
o
o
Mineralization hosted in veins
By 1964 only one mine remained in
operation in Beaverlodge Area
◦ Last mine closed in 1982
Pitchblende (uraninite)
11
12. o
Rabbit Lake Deposit discovered in
1968
◦ Incited staking rush and extensive
exploration
o
Rabbit Lake
New deposit models developed
◦ Unconformity-Associated Deposits
o
o
Prolific Eastern Athabasca Trend
revealed and focus of exploration
Eastern
Athabasca Trend
Patterson Lake South (PLS) Deposit
discovered in 2012 within southcentral Basin
o New staking rush in emerging district
12
13. o
McArthur River (production)
◦ Reserves of 1.05 Mt @ 16.4% U3O8 (378.9 Mlbs)
o
Rabbit Lake (production)
◦ Reserves of 1.47 Mt @ 0.70% U3O8 (22.8 Mlbs)
o
Key Lake (mined out*)
◦ *(stockpiled low grade ore used to dilute
McArthur River ore)
o
Cluff Lake (mined out)
◦ Produced ~63 Mlbs at ore grade of 0.93% U3O8
o
Cigar Lake (near-term producer)
◦ Reserves of 0.57 Mt @ 18.3% U3O8 (216.7 Mlbs)
o
3 processing mills located on eastern side
of Basin
◦ Key Lake, Rabbit Lake, McClean Lake (JEB)
Basin deposits are in the range of
Kt, not Mt, focused in 10’s of
metres wide, cigar shaped pods
with 100 m strike lengths
13
17. Quartz Dissolution Egress Style
(E.g. Cigar Lake, Midwest)
Silicification Egress Style
(E.g. MacArthur River, Key Lake)
*From Jefferson et. al. 2007
o Deposits often termed ‘blind deposits’ as cannot be detected directly
o Therefore, must use indirect methods (e.g. map clay alteration)
17
18. Evolution of Midwest Deposit
Idealized Basin Deposit Model
o Midwest Deposit discovered in 1978
o Located on northern end of Eastern
Athabasca Trend
o Indicated resource of 43 Mlbs @
5.50% U3O8
*From Sibbald et. al. 1991
18
19. o We are trending towards looking deeper to find deposits than before
o
o
o
o
o
o
o
o
Key Lake discovered in 1975
McClean Lake discovered in 1979
Midwest discovered in 1978
Cigar Lake discovered in 1981
McArthur River discovered in 1988
Millennium discovered in 2000
Phoenix discovered in 2008
Roughrider discovered in 2008
19
20. Boulder Prospecting
o
o
o
Method of tracing back mineralized boulder
fields to source based on knowledge of
glacial advances
Very powerful indicator of proximal
mineralization
Deposits found via this method
◦ Cluff Lake
◦ Rabbit Lake
◦ Patterson Lake South
◦ Maurice Bay
◦ Collins Bay
◦ Several others
20
21. Radon Sampling
o
o
o
o
Grid based collection of radon gas
at surface
Radon (Rn) is product of uranium
decay series and will migrate to
surface through rock fractures and
porosity
Radon gas
migrates to
surface
One the closest methods to direct
detection of a uranium ore body
there is
Credited with final targeting and
discovery at PLS in Nov 2012
21
22. Lake Sediment Sampling
o
o
o
Utilizes helicopter or boat to sample lake bottom
May also collect water sample (less valuable)
Pathfinder geochemistry important
◦ (Ni, Cu, B, As, Pb, Co)
o
Good tool for regional evaluation
Soil sampling
o
o
o
o
Grid based ground sampling
Must keep in mind glacial influences
Pathfinder geochemistry important
◦ (Ni, Cu, B, As, Pb)
Good tool to systematically evaluate smaller area
Other
o
o
Helicopter support lake sampling
Biogeochemical
sampling
Biogeochemical
Mobile Metal Ion (MMI)
22
23. Airborne Methods
o
Helicopter borne
VTEM plus survey
Electromagnetic (EM) Survey
◦ Locates conductors associated with deposits
o
Magnetic Survey
◦ Helps define geology (mag low may be
prospective meta-sediments), and structure
o
Eastern
Athabasca Trend
Radiometric Survey
◦ Measures RA (Th, U, and K) within ~ top 30
cm of surface
◦ Look for hot spots representing boulder
fields etc.
23
24. Ground Methods
o
Electromagnetic (EM) Survey
◦ Better defines conductors than airborne data
o
Gravity Survey
◦ Maps alteration through density contrast
◦ Gravity lows are targets (alteration destroys host rock)
o
Electromagnetic principle
DC Resistivity
◦ Maps clay alteration within sandstone
◦ Very common within basin
o
Other
◦ Magnetic Survey, Seismic
Gravity anomaly principle
24
26. Within Basin (<100 m to 800 m sandstone cover)
1.
Airborne EM, RA, and Magnetics
2.
Prospecting and ground sampling
3.
Ground DC Resistivity/ Gravity, EM, and Radon surveys
4.
Drill
Outside Basin (no sandstone cover)
1.
Airborne EM, RA, and Magnetics
2.
Prospecting and ground sampling
3.
Ground Gravity, EM, and Radon surveys
4.
Drill
o
Mineralized core
(Roughrider Deposit)
Approach is very similar within and outside of Basin with
Gravity – DC Resistivity the main difference
26
27. Patterson Lake South (PLS)
o
o
o
o
o
o
1977-81 – PLS corridor discovered, ground
radon anomaly defined, and drilling reveals
favourable geologic setting
Fall 2009 –Airborne RA survey confirms
historic RA anomaly, radon surveys
completed
Summer 2011 – Prospecting discovers
mineralized boulder train coincident with
RA anomaly
Fall 2011 – Drill program intersects
favorable geology and alteration
Winter/Spring 2012 – Airborne VTEM,
Ground DC-Resistivity, and SMLTEM
Surveys
November 5, 2012 – Discovery drill hole
released ‘PLS12-022’ (8.5 m of 1.07% U3O8)
No resource yet defined
One of the best intersections is:
PLS13-075’ (54.05 m of 9.08% U3O8)
Mineralization is near-surface (<200 m)
making deposit even more attractive
27
31. J-Zone and Roughrider – almost discovered prior
~100 m
o Historic drilling came close to discovering the deposits
o Deposits are cigar shaped and may be only 10’s of metres across making them very
difficult to find. Therefore, must put all clues together to find
o alteration, chemistry, geophysics, favourable geologic setting
31
32. Jefferson et. al. (2007) Empirical Models for Canadian Unconformity-Associated
Uranium Deposits, In “Proceedings of Exploration 07: Fifth Decennial International
Conference of Mineral Exploration, edited by B. Milkereit, p. 741-769
Jefferson et. al. (2007?) Unconformity Associated Uranium Deposits (DRAFT)
Sibbald et. al. (1991) Uranium Deposits of the Athabasca Basin, Saskatchewan (Field Trip 11)
, Open File 2166
Ford et al. (2007) Overview of Geophysical Signatures Associated with Canadian Ore Deposits,
in Goodfellow, W.D., ed. Mineral Deposits of Canada: A of Major Deposit-Types,
District Metallogeny, the Evolution of Geological Provinces, and Exploration Methods:
Geological Association of Canada, Mineral Deposits Division, Special Publication No 5.
5, p. 939-970
http://www.cameco.com/
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