GPX Geophysical
Exploration Services
IP
and DC Resistivity Surveys
The DC resistivity technique is better for
defining resistors in conductive terrain than the TEM method. The
peak received voltage, measured while the transmitter is on, can be used
to calculate an apparent resistivity for the sub-surface. This
apparent resistivity is equivalent to the resistivity of homogeneous, isotropic
ground which would give the same voltage-current relationship as measured.
This method has wide ranging applications in mineral exploration, groundwater
and environmental mapping.
The IP technique involves measuring a transient
decay after turning the transmitter off. While this appears similar
to the TEM method, different physical processes are being measured with
greatly differing time scales – 0 to 5 ms for TEM rather than 100 to 2000
ms for IP. For the IP technique the process measured is an electro-chemical
delay resulting from the conversion of current transport as ions in pore
solution to electrons through metallic grains. If disseminated sulphide
mineralisation is present then a slow electrical transient will be measured.
This method is predominantly used in mineral exploration.
Phase domain dipole-dipole
IP data
Construction of IP electrode
pits
E-mail : gpx@gpx.com.au
