Geonics Metal Detectors are high power, high sensitivity metal detectors suitable for applications in the detection of both ferrous and non-ferrous metal. Insensitive to common sources of both geologic and cultural noise, Metal Detectors can be operated without compromise to data quality in most survey environments.
Common applications, in several fields of geophysical practice, include the detection of environmental hazards (e.g. drums, underground storage tanks (USTs)); utilities and infrastructure; construction and industrial waste; and unexploded ordnance (UXO).
Within the exploration community there is a well known trade-off between depth of exploration and target definition in terms of conductivity, extent and orientation. Greatest depth is obtained with large fixed loop Turam-type systems which generate large half-space responses that, along with current gathering, makes target detection difficult. Better spatial resolution is obtained with a moving transmitter configuration with a short intercoil spacing, but is limited to a shallower depth of exploration. These variations in survey requirements make system flexibility an important design consideration.
Time domain systems are also routinely employed for general geological applications, such as exploration for freshwater aquifers in bedrock fractures, and mapping groundwater contaminant plumes. Investigations to shallow depths, as necessary in these applications, requires a very wide bandwidth and many narrow sampling gates.
Three interchangeable transmitters – TEM47, TEM57-MK2 and TEM67 – are used with the PROTEM receiver and an appropriate receiver coil to make up different PROTEM systems for various applications such as mineral exploration, structural mapping, resistivity sounding and contaminant plume mapping.
The TEM47 is the smallest and lightest battery operated transmitter, with a very fast turn-off time to enable measurement of the near-surface response. The PROTEM 47 (including PROTEM receiver, TEM47 transmitter) is most often used for shallow resistivity sounding of groundwater contamination, saline intrusion and geologic units. In this configuration, single turn transmitter loops from 5 m to 100 m on a side, with turn-off times as short as half a microsecond, can be used to give maximum near-surface resolution.
The TEM57-MK2 Transmitter is the upgraded version of the TEM57, and combined with the PROTEM receiver are the principal components of the PROTEM 57-MK2 system. The design and performance of the TEM57-MK2, with increased power of 1,500 W from an internal power supply, makes it a highly portable, powerful mid-range time domain transmitter. The internal power supply has variable voltage range from 18 to 60 V so that it can be precisely matched to the transmitter loop for optimum performance. An external battery supply increases performance to 3,800 W and 160 V.
The TEM67 transmitter is the most powerful of the current PROTEM transmitters, replacing the TEM37 of the previous generation. Not only is the TEM67 (3800 W) more powerful than the TEM37 (2800 W), but the new transmitter also provides an element of flexibility not previously available with time domain transmitters.
By consolidating the PROTEM receiver and TEM47 transmitter components into a single console, the PROTEM CM system offers significant improvements in portability and convenience: As compared to the individual receiver and transmitter components, the PROTEM CM is both smaller in size, and less in weight by about half. The increase in component portability will be of particular benefit for surveys in more demanding environments, both in-mine and over rugged terrain.
Available with cable reference synchronization only, for either single component or sequential three-component data collection, PROTEM CM otherwise offers the same functions and performance characteristics as the standard PROTEM 47 components, and is compatible with all other Geonics transmitters.
For greater depth of exploration, a high power (HP) modification to increase the output current from the transmitter section is available as an option.
With the objective to reduce cost while both maintaining the core performance characteristics of the more advanced PROTEM systems and adding several new performance-enhancing features, the new G-TEM system represents exceptional value in time domain electromagnetic (TDEM) instrumentation for both academic and commercial applications alike.
Designed as a complete system for exploration of the geologic near-surface, the modular G-TEM components are also compatible with all PROTEM system components, in cable reference mode only, supporting exploration to greater depths and a wider range of applications.
Six induction coils are available, each most appropriate for certain depths and applications. For shallow resistivity soundings, the high bandwidth of the high frequency coils is needed for the rapidly changing early-time signal. Comparatively, for deeper soundings, or for measuring late-time signal from conductive ore bodies, the larger effective area of the low frequency coils amplifies the very low amplitude late-time signals to measureable levels.