Time Domain Electromagnetic (TDEM) surveys are used to detect changes in subsurface conductivity. This can be particularly useful in the detection of base metal deposits due to the high contrast in conductivity between the ore body and the host rock. Other subsurface features such as saline and contaminated groundwater sources, paleochannels and shear zones present conductivity contrasts that can be detected using TDEM surveys.
Moving Loop Geophysical Surveys
GEM utilise leading geophysical technology such as the Smartem 24 receiver, which gives better resolution and lower noise levels. This geophysical technique allows for easy identification of conductors and drill targeting.
For deep targets we use GEM’s High Power transmitter, capable of 100A, combined with the JESSY DEEP High temperature SQUID or the JESSY DEEP Low temperature SQUID to best possible resolution at depth.
Other sensors available include Bartington three Component Fluxgate Magnetometers and Induction coils.
Large Fixed Loop Geophysical Surveys
Using low resistance wire, and modified transmitters, GEM can deliver maximum current (100A) through large transmitter loops.
These geophysical surveys are generally used to better define known conductors.
Down Hole Geophysical Surveys
Down hole geophysical surveys are an effective way to help model conductors and detect off hole conductors.
The DigiAtlantis is a sophisticated geophysical system that allows for rapid simultaneous collection of all three components to improve acquisition efficiency and data quality.
The DigiAtlantis is a B field sensor which gives it an advantage over coil probes, especially in conductive areas
The Geonics BH-43 coil probe measures all three components of the dB/dt response. It is suited to use in resistive environments.