VEXRAD • Mineral Exploration Guide
Geophysical Methods for Mineral Exploration
There is no single “best” geophysical method for mineral exploration. The right method depends on the physical property contrast, target geometry, depth, host geology, cover and decision you need to make.
Start with the geological question
What are you actually trying to resolve?
Regional architecture
Map major structures, intrusive bodies, basin geometry and broad geological domains before selecting detailed targets.
Target detection
Search for a measurable contrast associated with mineralisation, alteration, structure or the geological system that may host it.
Drill positioning
Use converging geological, geochemical and geophysical evidence to rank where direct testing can add the most information.
The exploration toolkit
What the principal methods actually measure.
| Method | Primary property / response | Useful for | Important limitation |
|---|---|---|---|
| Magnetics | Magnetic susceptibility / magnetisation | Structures, intrusions, lithological boundaries, magnetic alteration and magnetic minerals | A magnetic anomaly is not uniquely mineralisation |
| Gravity | Density contrast | Dense or low-density bodies, basin geometry, intrusions and regional architecture | Interpretation is non-unique and small deep bodies can be difficult to resolve |
| Induced Polarisation (IP) | Chargeability / polarisation | Especially useful for disseminated sulphides and alteration systems | Graphite, clays and other materials can create responses; geometry/depth matter |
| Electrical Resistivity | Electrical resistivity | Alteration, structures, fluids and contrasts between geological units | Different geological causes can produce similar resistivity |
| EM / TDEM | Electrical conductivity / induced EM response | Conductive sulphides, conductive horizons and structural/conductivity mapping | Conductive cover can mask deeper targets; sensitivity depends strongly on target and host |
| Magnetotellurics (MT) | Natural-field electrical resistivity structure | Deep crustal conductivity/resistivity architecture and large-scale systems | Deep sensitivity generally comes with coarser spatial resolution |
| Seismic | Elastic velocity / acoustic impedance contrasts | Structure, faults, contacts and detailed subsurface geometry | Can be relatively costly and interpretation depends on velocity/reflectivity contrasts |
| Remote Sensing | Spectral / surface properties | Regional mapping, alteration minerals, structures and rapid reconnaissance | Primarily surface or near-surface evidence; vegetation/cover can obscure geology |
| ADR / VEXRAD | Frequency, energy, dielectric and related EM responses | Depth-referenced lithological interpretation, boundaries, target intervals and Virtual Boreholes | Project-specific; requires careful interpretation and benefits from calibration and independent validation |
| Drilling | Direct physical sample / downhole evidence | Testing geology, mineralisation, grade and physical properties directly | Expensive point information; the challenge is choosing where to drill |
Method performance varies substantially with geology, survey design, equipment, target geometry and depth. This table is an exploration guide rather than a universal performance specification.
Why integration matters
An anomaly is evidence. It is not automatically an orebody.
Geophysical interpretation is an inverse problem: more than one geological model can often explain a measured response. A gravity high may reflect dense host rock rather than ore. Conductivity may arise from sulphides, but also from graphite, clay or saline fluids. A chargeability anomaly may be associated with disseminated sulphides without defining an economic deposit.
SCREENING↓
GENERATION↓
GEOPHYSICS↓
INTELLIGENCE↓
TEST
Choosing a method
Match the physics to the target.
If the target is magnetic…
Magnetics may provide rapid, cost-effective regional and prospect-scale mapping of magnetic contrasts and structure.
If the target is electrically conductive…
EM methods can be powerful, particularly for conductive sulphides, but target size, depth, host conductivity and overburden determine detectability.
If disseminated sulphides are expected…
IP can be particularly useful because chargeability responds to polarisation effects associated with disseminated metallic minerals.
If deep architecture matters…
MT, gravity, magnetics and seismic can provide complementary views of deep electrical, density, magnetic and structural architecture.
Where ADR fits
From an exploration anomaly to a depth-referenced geological question.
VEXRAD positions Atomic Dielectric Resonance as an additional subsurface-intelligence layer between broad exploration targeting and expensive physical drilling. ADR measurements are processed into depth-referenced interpretations and, where appropriate, a Virtual Borehole at a proposed target location.
Integrate
Start with the geological model, remote sensing, geochemistry, existing geophysics and drilling rather than treating ADR in isolation.
Interrogate
Acquire ADR at selected surface locations and process the response into depth-referenced subsurface evidence.
Test
Rank interpreted intervals and compare predictions with drilling or other independent ground truth wherever possible.
The Virtual Borehole
A borehole before the borehole.
A VEXRAD Virtual Borehole converts surface-acquired ADR measurements into a depth-referenced interpretation designed to help identify lithological changes, boundaries and intervals worthy of further investigation.
What it can help with
- Lithology and formation boundaries
- Structures and subsurface changes
- Target intervals
- Mineralisation indicators
- Correlation between selected locations
- Prioritising further investigation
What it does not guarantee
- Assay grade
- Resource or reserve estimates
- Commercial discovery
- Unique geological interpretation
- Drilling success
- A replacement for physical ground truth
Frequently asked questions
Mineral exploration geophysics FAQs
What is the best geophysical method for mineral exploration?
There is no universally best method. Selection should follow the expected physical-property contrast, target geometry and depth, host geology, cover and exploration objective. Multiple complementary methods are often more informative than one method alone.
Which geophysical method is used to find sulphides?
EM methods are widely used for conductive sulphides, while induced polarisation is particularly useful for many disseminated sulphide systems. Their effectiveness depends on mineralogy, geometry, host properties, depth and survey design.
Can geophysics identify an orebody without drilling?
Geophysics can identify anomalies and constrain geological models, but an anomaly is not uniquely an economic orebody. Drilling and sampling remain important for direct geological and grade information.
How deep can mineral exploration geophysics see?
There is no single depth limit. Different methods operate over very different depth scales, and useful depth depends on geology, target size, physical-property contrast, survey geometry and the resolution required.
What is a VEXRAD Virtual Borehole?
It is a depth-referenced interpretation generated from surface-acquired ADR measurements, designed to add subsurface evidence before physical drilling.
The method starts with the target
Bring us one mineral exploration target.
Send VEXRAD the geological question, proposed drill location and the evidence you already have. We can assess whether ADR could add useful subsurface intelligence before more drilling capital is committed.