Exploration Potential, page-127

While piezoelectricity itself isn’t directly measured in exploration geophysics, several geophysical methods can indirectly detect the conditions and structures that favor piezoelectric effects and electrochemical gold mobilization—like quartz-rich zones, fault conduits, and fluid pathways.

Here are the best geophysical methods and examples where they’ve successfully aided exploration in structurally complex, gold-bearing systems with potential for seismic/electrical reworking:

1. Induced Polarization (IP) – Best for Mapping Sulfides & Alteration Zones

What it detects:

• Chargeability anomalies associated with disseminated sulfides (e.g., pyrite, arsenopyrite) that commonly accompany gold.

• Clay alteration zones formed by hydrothermal fluids.

Why it matters:

• Zones of past fluid flow and sulfide deposition are often conduits for gold, especially if later reactivated by seismic activity.

• IP anomalies can highlight fault zones and breccias that may have focused both primary and electrochemical mineralization.

Example – Fosterville (VIC):

• IP helped identify disseminated pyrite and arsenopyrite halos along fault zones that hosted visible gold.

• Although the gold itself was not directly detectable, the alteration halo helped delineate the Swan and Eagle zones.

2. Resistivity / Electrical Resistivity Tomography (ERT) – Best for Structural Mapping

What it detects:

• Contrasts between resistive quartz veins and conductive carbonaceous shales, sulfides, or fault gouge.

• Deep conductive anomalies associated with faulted zones or altered rock.

Why it matters:

• Gold-bearing quartz veins (which may also be piezoelectric) appear as resistive features, while surrounding conductive units highlight the structural architecture.

• Helps map vein continuity, plunging shoots, and deep fault systems where seismic or fluid-driven enrichment may have occurred.

Example – Beaconsfield (TAS):

• Resistivity surveys delineated the Tasmania Reef (a resistive quartz vein in a conductive shale sequence), aiding deep targeting below known workings.

3. Magnetotellurics (MT) – Best for Deep Crustal Structures

What it detects:

• Conductivity contrasts in the crust and upper mantle, especially deep fault corridors and fluid pathways.

Why it matters:

• MT can image crustal-scale fault zones that acted as lithospheric fluid conduits, where deep metamorphic fluids and later seismic processes focused mineralization.

Example – Bendigo Zone (VIC):

• Regional MT identified crustal-scale structures correlating with major lines of reef and fold axes.

• Suggested that deep-seated structures were critical to gold fluid ascent and later reactivation.

4. Seismic Reflection (Hard Rock) – High-Resolution Structural Imaging

What it detects:

• Reflective contrasts at lithological and structural boundaries (e.g., faults, folds, quartz veins).

Why it matters:

• High-resolution 2D/3D seismic can image dilational fault jogs, fold hinges, and stacked vein arrays, even in complex geology.

Example – Cobar Basin (NSW):

• Seismic reflection helped map stacked vein systems and blind faults associated with Cu–Au mineralization.

• Similar techniques could image reactivated vein systems at Hill End, especially where thick metasedimentary cover exists.

5. Self-Potential (SP) and Spontaneous Polarization (less commonly used)

What it detects:

• Natural voltage differences generated by subsurface fluid flow, potentially highlighting active fault zones or mineralized zones.

Why it matters:

• Theoretically capable of detecting ongoing electrochemical gradients, although very sensitive to background noise.

• Rarely used alone, but sometimes helpful in mapping groundwater pathways that might overlap with seismic/electrical reworking zones.

Summary Table: Best Geophysical Methods for Seismically Influenced Gold Systems

	Method	Detects	Usefulness for Piezoelectric/Electrochemical Models	Best Use Case
1	Induced Polarization (IP)	Sulfides, alteration halos, fault zones	Maps fluid pathways and sulfide-rich zones where gold may have precipitated	Delineating targets near fault intersections
2	Resistivity/ERT	Contrasts between quartz, shale, faults	Highlights resistive quartz veins & conductive faults for structural mapping	Imaging quartz vein continuity and deep targets
3	Magnetotellurics (MT)	Deep fluid pathways, crustal-scale faults	Detects deep conduits for fluids and post-mineralization reactivation	Regional structure and deep targeting
4	Seismic Reflection	Faults, folds, lithological boundaries	Images vein arrays, fault offsets, and shoot geometries	Detailed imaging under cover or complex structure
5	Self Potential (SP)	Natural electrochemical gradients	May detect active fluid/electric anomalies (rare)	Experimental – niche application