uranium mineral systems: ore-forming processes and ... · onshore energy & minerals division....

SGA, Townsville 2009

R. Skirrow, A. Schofield, S. van der Wielen, D. Huston, S. Jaireth, E. Bastrakov

Onshore Energy & Minerals [email protected]

Uranium mineral systems: ore-forming processes and

relationships among deposit types


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)


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


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


BASIN- and SURFACE-RELATED

METAMORPHIC- RELATED

MAGMATIC-RELATED

Mineralsystemsmodels(cf. deposit models)

HYBRIDS(IOCGU,

etc)

Deposit model


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)


Magmatic-related uranium systems: critical mineralising processes

Based on concepts outlined by Cuney & Kyser (2008)


Magmatic-related uranium systems

Previous image

Based on concepts outlinedby Cuney & Kyser (2008)

S = StreltsovkaK = KvanefjeldRA = Ross AdamsR = RossingMC = Massif Central


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


Nth Queensland magmatic-related U potential200 km


200 km

Nth Queensland magmatic-related U potential


Nth Queensland magmatic-related U potential200 km


200 km



200 km


Regions with high potential for orthomagmatic, magmatic-hydrothermal and ‘secondary’ magmatic-related uranium

(work in progress)


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


Basin-related uranium potential of north Queensland


• 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


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

uranium mineral systems: ore-forming processes and ... · onshore energy & minerals division....

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