3D Mineral Potential Modelling and Greenfields Exploration

in Queensland

Matthew Greenwood

Greenfields Prospectivity Unit Geological Survey of Queensland

Department of Natural Resources and Mines

Quamby Project Area• Project area covers an

area of 95km long by 80km wide. Located immediately north of Cloncurry

• Includes the major operating Ernest Henry copper - gold mine as well as significant copper and gold projects such as Rocklands and Roseby, and the Dugald River Silver – Lead – Zinc deposit

Mineralisation Potential• Recent sediments cover >70% of

the area with most cover depths interpreted to be less than 200m. Consequently, much of the area has been under-explored

• Quamby area is prospective for multiple styles of mineralisation including Cu±Au±iron oxide deposits, sediment-hosted Cu deposits, sediment-hosted Ag-Pb-Zn deposits, Au and Cu veins and Cu skarns

• Known mineralisation mostly confined to outcropping areas. But some large systems discovered under shallow cover. High potential for greenfields discovery

3D Weights of Evidence (WoE) Targeting

• Jar of 1000 marbles

• 1/1000 chance of randomly picking the right one

• But what if you had more information?

• Statistical evaluation of relationships between known mineral occurrences and exploration datasets (such as rock type, structure, geochemistry)

used to define mineral potential probabilities

3D Weights of Evidence (WoE) Targeting

• Statistical evaluation of relationships between known mineral occurrences and exploration datasets (such as rock type, structure, geochemistry)

used to define mineral potential probabilities

• Previous studies identified geological objects and properties (exploration criteria) believed to be associated with Copper - Gold mineralisation in area

• Exploration criteria represented in the model and tested against known mineral occurrences (How strong is the association?)

• Mineral Potential index is a combination of the statistically significant exploration criteria. Highlights locations with similar sets of these properties to known mineral occurrences

3D Weights of Evidence

• Weights assigned from correlation between mineral occurrences and evidential properties.

• Continuous properties converted to binary properties (favourable region and non-favourable region)

• 23 evidential properties tested

• Two different model areas were tested due to different styles of mineralisation in these areas

Distance to Crustal Scale Faults

Distance to Granites

3D Weights of Evidence

• Weights assigned from correlation between mineral occurrences and evidential properties.

• Continuous properties converted to binary properties (favourable region and non-favourable region)

• 23 evidential properties tested

• Two different model areas were tested due to different styles of mineralisation in these areas

Distance to Crustal Scale Faults

Distance to Granites

Mineral Potential Index – Constantine Domain

• Targeting mainly Copper – Gold mineral systems

• Most important exploration criteria

– Geochemical anomalies– Geophysical anomalies– Proximity to faults– Uranium anomaly

• Weighted criteria combined to create Mineral Potential Index

Mineral Potential Index – Constantine Domain

• Targeting mainly Copper – Gold mineral systems

• Most important exploration criteria

– Geochemical anomalies– Geophysical anomalies– Proximity to faults– Uranium anomaly

• Weighted criteria combined to create Mineral Potential Index

Copper Geochemistry

Density inversion

Distance to Faults

Uranium Anomaly

Mineral Potential Index – Constantine Domain

Horizontal slice at 100m (outcrop - ~100m cover)

Red Spheres are known mineral occurrences

Mineral Potential Index – Constantine Domain

Horizontal slice at -100m (~200 - ~400m cover)

Red Spheres are known mineral occurrences

• Targets include – Copper-Gold mineralisation– Copper only

• Most important exploration criteria

– Geochemical anomalies– Geophysical anomalies– Proximity to faults– Potassium anomaly

• Different strengths of association

• Less variation in 3D than in Constantine Domain

Mineral Potential Index – Mary Kathleen Domain

Conclusions• The creation of 3D models, geophysical inversion and mineral

potential modelling is value-adding to the large set of pre-competitive data available to explorers from the GSQ

• These products will– Attract exploration interest and investment– Reduce risk and improve efficiency exploration– Improve exploration strategies and landuse decisions– Encourage new greenfields exploration

• Greenfields exploration will lead to new discoveries and ensure a healthy resource future for Queensland