Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

Macro-scale targeting of magmatic- related uranium mineral systems

Anthony Schofield and Roger SkirrowUranium Systems Project

Onshore Energy & Minerals Division

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

Outline

1. Why bother mapping the U contents of igneous rocks?

2. Data compilation and map production3. ‘Ingredients’ in magmatic-related U mineral

systems4. North Queensland prospectivity analysis5. Conclusions

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

Magmatic-related U mineral systems

• Refers to mineralisation where igneous processes are the primary control

• May be volcanic or intrusive

• Includes U systems associated with exsolved magmatic fluids

• Definition does not include systems such as IOCG

BASIN- and SURFACE-RELATED SYSTEMS

‘METAMORPHIC’- RELATED SYSTEMS

MAGMATIC- RELATED SYSTEMS

Magmatic-hydrothermal

fluids

‘Metamorphic’fluids

Meteoric, seawater

IOCG-Udeposits

Skirrow et al., 2009

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

Australia’s U resources associated with igneous rocks

• Intrusive + volcanic <1.3% total resources

• ~20,000 tonnes U

• Streltsovka caldera (Russia): 232,000t U @ 0.2%

• Where are Australia’s large magmatic-related deposits?

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

Assessing Australia’s potential for magmatic-related U

1. Compile national-scale geochemical and geological data

2. Process-based “ingredients” for magmatic- related U

3. Identify regions with high prospectivity at a macro-scale

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

Data compilation workflowGeochemistry•OZCHEM•State and Territory data

Surface geology•GA 1:1,000,000 surface geology

Solid geology•Best available State and Territory datasets

Data filtering ArcGIS

Thematic maps Thematic mapsThematic maps

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

Uranium content of igneous rocks of Australia maps

Available for download at:www.ga.gov.au/minerals/research/national/uranium

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

Assessing Australia’s potential for magmatic-related U

1. Compile national-scale geochemical and geological data

2. Process-based “ingredients” for magmatic- related U

3. Identify regions with high prospectivity at a macro-scale

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

Key mappable ‘ingredients’

• Crustal (i.e., felsic rocks)

• High temp melting• Fractionated (Rb/Sr) • High U solubility

(peralkaline, Cl, F)• Bulk rock composition

(e.g. A-type)• ± exotic compositions

(e.g. lamprophyre)Time, leaching ‘Secondary’

U systems

‘Orthomagmatic’U systems

•High-level emplacement

•High U availability

•Fluids

‘Magmatic- hydrothermal’U systems

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

Assessing Australia’s potential for magmatic-related U

1. Compile national-scale geochemical and geological data

2. Process-based “ingredients” for magmatic- related U

3. Identify regions with high prospectivity at a macro-scale

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

North Queensland case study - source

Cairns

Townsville

200 km

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

U availability

Cairns

Townsville

200 km

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

Prospectivity

Cairns

Townsville? ?

?

?

200 km

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

Conclusions

• U content of igneous rocks has been mapped at a national scale

• U-rich igneous rocks may act as a vector towards orthomagmatic, magmatic- hydrothermal, and secondary U mineral systems

• Process-based analysis of compiled data allows prospective regions to be delineated on a macro-scale

Macro-scale targeting of magmatic-related uranium mineral systemsAusIMM uranium conference, Darwin, 10/06/09

www.ga.gov.au/minerals/research/national/uranium