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SGA, Townsville 2009
R. Skirrow, A. Schofield, S. van der Wielen, D. Huston, S. Jaireth, E. Bastrakov
Onshore Energy & Minerals Divisionroger.skirrow@ga.gov.au
Uranium mineral systems: ore-forming processes and
relationships among deposit types
SGA, Townsville 2009
Topics
1. Relationships among U deposit types: A revised framework for deposit classification
2. Application of process-based mineral systems models to regional-scale targeting of U mineralisation (part of Energy Security Program)
SGA, Townsville 2009
Uranium deposit classificationMost widely used: IAEA ‘RED BOOK’In order of economic importance in Australia:1. Breccia complex (Iron Oxide Cu-Au)2. Unconformity-related3. Sandstone4. Surficial5. Metasomatite6. Metamorphic7. Volcanic8. Intrusive9. Vein10. Quartz-pebble conglomerate11. Collapse breccia pipe12. Phosphorite13. Lignite14. Black shale
• Based on host-rock or deposit morphology
• Relationships between deposit types not clear
SGA, Townsville 2009
Magmatic-hydrothermal
fluids
‘Metamorphic’fluids
(incl. metamorphicrock-buffered)
Meteoric, seawater
Groundwaters
Formation waters / connate waters
Diagenetic fluidsm
ixing
mixing
mixi
ng
Deep (mgt) IOCG
(1) Shallow U-bearing hematite
IOCG
(2) Unconformity U (PGE, Au)
(3) Sandstone U (V, Cu)
(4) Calcrete U
(7) Volcanic(8) Intrusive(9) Vein
BASIN- and SURFACE- RELATED
U SYSTEMS
‘METAMORPHIC’- RELATED
U SYSTEMS(6)
MAGMATIC- RELATED
U SYSTEMSHYBRID
U SYSTEMS(1,5,9,10,11)
(5) Metasomatic(9) Vein
(10,12,13,14)
(7) Volcanic
(#) represent deposit types from IAEA Red Book & Dahlkamp (1990)
An alternative view: 3 families of uranium mineral systems
• Three end-member fluids• Continuum of deposit styles• Emphasis on commonalities• Hybrids are expected
SGA, Townsville 2009
BASIN- and SURFACE-RELATED
METAMORPHIC- RELATED
MAGMATIC-RELATED
Mineralsystemsmodels(cf. deposit models)
HYBRIDS(IOCGU,
etc)
Deposit model
SGA, Townsville 2009
Application of the U systems conceptual framework to exploration targeting
1. Identify critical mineralising processes for each family of U mineral systems
2. Translate into mappable criteria 3. Build GIS layers; assign weightings 4. Produce regional and national scale
maps of uranium potential for each system
(Wyborn et al., 1994; Barnicoat et al., 2007; McCuaig & Beresford, 2009)
SGA, Townsville 2009
Magmatic-related uranium systems: critical mineralising processes
Based on concepts outlined by Cuney & Kyser (2008)
SGA, Townsville 2009
Magmatic-related uranium systems
Previous image
Based on concepts outlinedby Cuney & Kyser (2008)
S = StreltsovkaK = KvanefjeldRA = Ross AdamsR = RossingMC = Massif Central
SGA, Townsville 2009
Magmatic-related U systems: Key mappable criteria (‘ingredients’):• Peralum, peralk, A-
type, high-T I-type• High temp melting• Highly fractionated
(Rb/Sr)
• High U solubility (peralkaline, Cl, F)
• Volcanic vs plutonic• High U content• etc ‘Secondary’
magmatic-relatedU systems
‘Orthomagmatic’U systems
‘Magmatic- hydrothermal’U systems
SGA, Townsville 2009
Nth Queensland magmatic-related U potential200 km
SGA, Townsville 2009
200 km
Nth Queensland magmatic-related U potential
SGA, Townsville 2009
200 km
Nth Queensland magmatic-related U potential
SGA, Townsville 2009
200 km
Nth Queensland magmatic-related U potential
SGA, Townsville 2009
200 km
Nth Queensland magmatic-related U potential
SGA, Townsville 2009
200 km
Nth Queensland magmatic-related U potential
SGA, Townsville 2009
Nth Queensland magmatic-related U potential200 km
SGA, Townsville 2009
200 km
Nth Queensland magmatic-related U potential
SGA, Townsville 2009
200 km
Nth Queensland magmatic-related U potential
SGA, Townsville 2009
200 km
Nth Queensland magmatic-related U potential
SGA, Townsville 2009
200 km
Nth Queensland magmatic-related U potential
SGA, Townsville 2009
200 km
Nth Queensland magmatic-related U potential
Regions with high potential for orthomagmatic, magmatic-hydrothermal and ‘secondary’ magmatic-related uranium
(work in progress)
SGA, Townsville 2009
LakewaterBitternBasinal / connate brineMeteoric waterMetamorphic fluidOil / gas / H2 S
sandstone U styles: paleochannel
rollfront
unconformity-related U(basement hosted style)
tabular
Westmoreland U style
Basin-related uranium systems
radiogenicheat
SCALE: 1 to 50 km
1 to 5 km
Different deposit styles: related processes
mafic
aquicludeaquifer
basement(meta-sedimentary, meta-igneous)
weathered granite
SGA, Townsville 2009
Basin-related uranium potential of north Queensland
SGA, Townsville 2009
• High-U source (from radiometric data)
• U anomalies in basin (from radiometric data)
• Groundwater pH gradient (at pH 7)
• Groundwater eH gradient (at eH 0mV)
• Mesozoic basin margin
Plus• Gamma-ray
anomalism in drill holes (contours)Uranium potential
Criteria ranked by distance from:
Uranium potential in Mesozoic basins
SGA, Townsville 2009
Conclusions
3 families of U mineral systems in ternary scheme, based on fundamental fluid types and settings:
Hybrids exist in continuum; new discoveries may not look like known deposit styles.Application of ‘systems’ approach: new areas identified with high potential for uranium mineralisation.
Basin- and surface-related
Metamorphic-relatedMagmatic-relatedhybrids
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