Transcript Unconformity-associated uranium deposits

TYPES OF URANIUM
DEPOSITS
Virginia T. McLemore
New Mexico Bureau of
Geology and Mineral
Resources
New Mexico Institute of Mining
and Technology, Socorro,
NM
Outline
• How do we classify mineral
deposits?
• Formation of uranium deposits
• Parameters
• Types of deposits
• What are the major types in
North America
HOW DO WE CLASSIFY
MINERAL DEPOSITS?
HOW DO WE CLASSIFY
MINERAL DEPOSITS?
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Tectonics
Mineralogy
Chemistry
Host rock
Commodity
Form
Mining method
Orogenesis
Foramtion of uranium
deposits
• ore-element source
• mineralizing fluid
source
• mobilization
mechanism
• migration
mechanism and
form
• regional migration
control
• local migration
control
• internal
environment (fluid
character)
• at deposition site
• external
environment (rock
character) at
deposition site
• concentration
mechanism
• fixation mechanism
• preservation
What important
parameters to
characterize uranium
deposits?
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location
shape
size
depth
orientation
geotectonics
mineralogy
hydrology
boundary conditions
TYPES OF DEPOSITS
• Unconformity-related
deposits
• Sandstone deposits
• Quartz-pebble
conglomerate
deposits
• Vein deposits
• Breccia complex
deposits
• Intrusive deposits
• Phosphorite deposits
• Collapse breccia pipe
deposits
• Volcanic deposits
• Surficial deposits
• Metasomatite deposits
• Metamorphic deposits
• Lignite
• Black shale deposits
• Other types of deposits
Hitzman and
Valenta, 2005,
Economic Geology,
v. 100, pp. 1657–
1661
Unconformity-associated
uranium deposits
Types of Unconformityassociated
uranium deposits
• Clay-bound Proterozoic
unconformity
• Strata-bound Proterozoic
unconformity
• Strata-bound proterozoic
unconformity
• Phanerozoic unconformityrelated
Unconformity-associated
uranium deposits
• Massive pods, veins and/or disseminated
uraninite associated with unconformities
between Proterozoic siliciclastic red beds and
metamorphic basement that includes graphitic
metapelite and radiogenic granite.
Unconformity-associated
uranium deposits
• Pitchblende fills extensional features in
reactivated fault zones and replaces matrix in
sandstone
• One mining district in Canada
– the Athabasca Basin
- >30 deposits /prospects
- most in eastern ¼ of basin
- produces 1/3 of world’s U
World Unconformity-associated U Deposits
590 Economic / potential U deposits all types >500 Tonnes U @ >0.03% U (IAEA)
Distribution and value
of Unconformity U
deposits in Canada
A
Resources,
Athabasca Basin (A):
553,778 Tonnes U
@ 1.922 % U (average)
Up to 25% U (P2)
$30,237,488,300
($30 billion)
E
T
H
Commodities
U >> Ni >>Au,Cu,PGE
18 deposits mined,
all in Saskatchewan:
Hw
S
C
O
Cigar Lake (~2007)
Cluff Lake (7), Collins Bay
(3), Eagle Pt., Key Lake (2)
McArthur R (P2), McClean
Lake (2), Rabbit Lake
Prospective basins
One deposit type, two end-member fluid flows
One deposit type, two extremes of alteration
Quartz dissolution,
e.g. Cigar Lake
Early silicification,
e.g. McArthur River
Temporal Distribution of U Deposits
W
Summary:
Unconformity-associated U Deposit
Empirical Geological Model
E
faults
alteration
Grow
grow
hill
Mono- -basement hosted
-uranium
metallic -Lower total REE
c
lit i
na s s
t o ne i
g
Z.
S.
ite
+
lite it e
pe m
ta - am
m e a- ps
t
me
c
iti
r tz
ua
taq
h
ap
gr
me
old valley
Quaternary
Athabasca
Group
unconformity
regolith
> 1750 Ma
intercalated
ortho- and
paragneiss
~ 100 m
-”sandstone” hosted
Poly- -U, Ni, Co, Cu, As
metallic -high total REE
Key Exploration Criteria for
Unconformity-Associated Uranium Deposits
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Tectonic settings: Intra-cratonic; late collisional farfield stresses
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Basin
Repeated fault reactivation, paleo-valleys,
hills
Architecture: Fluvial systems, 1780-1540 Ma, sources
<150 km
 Geophysics: EM - graphitic basement metapelite; need
deep systems
AMT new deep conductors, resistivity maps
alteration
Seismic maps unconformity and intersecting
structures
Key Exploration Criteria for
Unconformity-Associated Uranium Deposits
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Paleo-Environment: Warm & humid, intense weathering,
red regolith
Geology: Drilling, structural models: faults,
intersections
Modeling: 1st hydrothermal fluids 1670, 2nd 1450 Ma,
remobilized
Hydrocarbons and pyrobitumens post-U
(controversy).
Major unconformity type
deposits in the world
• Athabasca Basin,
Saskatchewan, Canada
• Pine Creek Geosyncline,
Northern Territory, Australia
SANDSTONE
CANA
Highland
M ountains
Bighorn
Basin
DA
Powder
River
Basin
B
Brid ger and Green
River basins
Positive area
Area of volcanic activity
Dominantly lacustrine sedimentation
4
6
H
Postulated sediment transport
Uranium deposits
9 G
Uin ta and Gr een
River basins
South
Park
b asin
I
10
J
M
L
K
N
G
O
Black Mesa
b asin
200 km
P
(after Everhart (1985) and Finch (1967).
Dominantly continental sedimentation
D 3
E 7
Context of Uranium deposits
in Eocene sandstone
of Western USA
San Juan
b asin
Positive areas:
A = Black Hills; B = Bighorn Mts., C = Owl Creek Mts,
D = Wind River Range, E = Rock Springs Uplift, F =
Laramie Mts., G = Front Range, H = Uinta Range, I =
Sa Rafael Swell, J = Uncompaghre Up-warp, K = San
Juan Mts., L = Kaibab Up-warp, M = Circle Cliffs Upwarp, N = Monument Up-warp, O = Defiance Upwarp,
P = Zuni Up-warp.
Basins:
3 = Wind River, 4 = Shirley, 6 = Hanna, 7 = Washakie,
9 = North Park, 10 = Green River.
Quartz-pebble
conglomerate deposits
Quartz-pebble
conglomerate deposits
• Upper Archean to Lower Proterozoic age
• consist of detrital ore minerals of uranium
and other metals
• pyrite
• Interbedded within siliciclastic sequences
containing layers of quartzite and argillite
• mineralized conglomerates.
• Blind River, uranium and rare earth elements
base of the stratigraphic sequence above the
unconformity.
• In the Witwatersrand, uranium in multiple beds
dispersed through a thick stratigraphic
sequence and is recovered as a by-product of
gold production.
Quartz-pebble
conglomerate deposits
• Blind River — Elliot Lake,
Ontario, Canada
• Witwatersrand, South Africa
Veins
Veins
• lenses or sheets in joints, fractures,
breccias or stockworks.
• pitchblende and/or coffinite
• Size veins varies
• spatially related to granite
• transect metamorphic or
sedimentary rocks
• Breccia complex uranium deposits
Breccia complex deposits
Iron oxide-copper-gold
(IOCG) deposits
Breccia complex deposits
Iron oxide-copper-gold
(IOCG) deposits
• Olympic Dam deposit
• hematite-rich granite breccia
• iron, copper, uranium, gold, silver,
rare earth elements (mainly
lanthanum and cerium) and fluorine
• hydraulic fracturing, tectonic
faulting, chemical corrosion, and
gravity collapse
Hitzman and Valenta, 2005, Economic Geology, v. 100, pp.
1657–1661
Olympic Dam deposit in
Australia
• Measured resource of 650
million tons (Mt) of 500 g/t U3O8
(425 ppm U), 1.5 percent Cu,
and 0.5 g/t Au
• Total resource approximately
3.8 billion tons of 400 g/t U3O8
(339 ppm U), 1.1 percent Cu,
and 0.5 g/t Au.
Hitzman and Valenta, 2005, Economic Geology, v. 100, pp. 1657–1661
Barton et al, 2000
Surficial deposits
Surficial deposits
• young (Tertiary to Recent) nearsurface uranium concentrations
in sediments or soils
• secondary cementing minerals
including calcite, gypsum,
dolomite, ferric oxide, and
halite
• uranyl minerals or adsorbed on
other materials
Calcrete deposits
• uranium-rich granites were
deeply weathered in a semi-arid
to arid climate
• valley-fill sediments along
Tertiary drainage channels, and
in playa lake sediments
• Lake Raeside, Australia
Volcanic deposits
Volcanic deposits
• acid volcanic rocks and are
related to faults and shear
zones within the volcanics
• commonly associated with
molybdenum and fluorine
Lakeview U District
225 t U3O8 production (1960s)
unknown resource remains
Now an EPA Superfund site
Withdrawn from mining til 2013
Lucky Lass Mine
White King open pit
White King Mine
Dump samples as much as
0.3% U3O8
1.8% Pb
1% As
0.4% Hg
also elevated Cs, Mo, & Sb
Steve Castor, 2007
Basalt flows
1 cm
1.3% U3O8
U Silicophosphate
Galena
Debris
flows
Peraluminous
flow-banded
Breccia
rhyolite
ore
Volcanic
sediment
Clay
alteration
Steve Castor, 2007
Uranium Mineralogy
Autunite filled fractures within
volcanic ignimbrites, Macusani
Peru.
(Solex Resources Corp.)
(Strathmore Minerals Corp.)
Intrusive deposits
Intrusive deposits
• Alaskite
• Rössing, Namibia
• Granite, Monzonite
• Bingham Canyon, Utah, USA
• Pegmatite
• Bancroft area, Ontario, Canada
• Peralkaline syenite
• Kvanefjeld, Greenland
• Carbonatites
• Phalaborwa, South Africa
Phosphorite
Phosphorite
• fine-grained apatite in
phosphorite horizons within
interbedded marine muds,
shales, carbonates and
sandstones
• primary bedded (Phosphoria
Formation, Utah–Idaho)
• sedimentologically reworked
(Florida) phosphorite
Collapse breccia pipe
Collapse breccia pipe
• Circular, vertical (up to 1000
metres in vertical extent) pipes
filled with down-dropped coarse
and fine fragments stopped
from the overlying sediments
• Mineralized pipes range from 30
to 200 metres in diameter
• Orphan mine, Arizona, USA
What are the major uranium
deposit types in North
America?
Major Uranium Deposit
Types – North America
• Unconformity
• Athabasca Basin, Saskatchewan and
Thelon Basin, NWT
• Sandstone
• Intermountain basins of Wyoming; Colorado
Plateau; Gulf Coast Plain of Texas; Grants
Mineral Belt, New Mexico
• Breccia Pipes
• Northern Arizona
• Quartz-pebble conglomerate
• Elliot Lake