Ground GeophysicsInduced Polarisation

Induced Polarisation (IP) is a technique of measuring an induced potential field in the ground in order to map the geological subsurface. From measurements of the induced potential field the chargeability and resistivity of the subsurface can be calculated.

These measurements are made in either the time domain or frequency domain using various configurations of transmission electrodes and multiple potentiometer receivers.

Please click here for a flyer about ground IP.

APPLICATIONS

Mineral Exploration and Mine Operations
IP and resistivity surveys can be used to detect and map economic mineral deposits, in particular those associated with disseminated sulphides and massive sulphide mineralisation. One of the major strengths of IP is that the technique is sensitive enough to detect disseminated sulphides which are often not measurable with EM systems. IP has been used to map many types of deposits including porphyry copper, gold bearing sulphides, manganese and titanium bearing placers.

Ground Water & Environmental Mapping
The boundary between subsurface water and surrounding soils and/or rocks can be highly resistive. Therefore resistivity surveys can lead to the discovery and mapping of underground aquifers. Similarly IP can be used to map pollution plumes at industrial sites and mine operations.

Stratigraphy Mapping for Civil and Geotechnical Engineering Projects
Knowledge of soil and rock stratigraphy is critical to many civil and geotechnical engineering projects. IP is an excellent technique to map the stratigraphy due to the differing chargeability/resistivity characteristics of different soils and rocks.

TECHNIQUES

The two techniques that are used in IP surveys are Time Domain and Frequency Domain.

Time domain IP
Time domain IP involves transmitting current into the ground and then switching it off. The current flow induces a potential field which the receivers measure during the on and off time. The voltage peaks during the on-time and begins to decay as soon as the current is switched off. From the on-time peak voltage measurement the apparent resistivity can be calculated. Chargeability is calculated from the off-time measurements of the transient voltage decay.

In comparison to TEM - which measures the decay of an induced EM field - IP measures the decay of an induced voltage and is therefore measuring a different physical property of the rock. IP is better at defining resistors in conductive terrain than TEM.

Frequency domain IP
In frequency domain IP an alternating current is transmitted into the ground at a low frequency which induces a potential field in the subsurface. The receivers measure the phase shift in the signal and from this the chargeability and resistivity can be calculated.
IP and resistivity surveys are primarily used in mineral exploration but have wide ranging applications in groundwater and environmental mapping, civil and geotechnical engineering projects and mine site operations.

EQUIPMENT SPECIFICATIONS

GPX offer a range of IP equipment including both Time Domain and Frequency Domain systems. Click on the links for specifications.

Type	Transmitter	Size
	Zonge Engineering NT-20	116kb
	Zonge Engineering ZT-20
	Zonge Engineering ZT-30	234kb
	Zonge Engineering GGT-3	62kb
	Zonge Engineering GGT-10	220kb
	Zonge Engineering GGT-30	501kb

Type	Reciever	Size
	Zonge Engineering GDP-16
	Zonge Engineering GDP-32	500kb
	GDD Instrumentation GDD-32	500kb
	Iris ELREC6	500kb
	Iris ELREC Pro	500kb
	Scintrex IPR-12	500kb