Using MT Technologies For Rapid, Cost Effective and Accurate Diamond Detection
MT in the search for diamond-bearing kimberlite pipes
Most of the world's diamonds have been found in volcanic rock formations called kimberlite pipes, after the town of Kimberley, South Africa, where the first such pipe was discovered. Diamonds are formed at depths as great as 150 km, where heat and pressure compress carbon into the tetrahedral crystalline structures. For unknown reasons, molten rock from those depths sometimes rushes upward through ancient rock fractures (tectonic faults) carrying the diamonds with it. When the hot rock reaches the water table, the resulting explosive eruptions produce characteristic carrot-shaped pipes relatively near the surface of the earth.
Although kimberlite pipes are often associated with magnetic or conductivity anomalies that can be detected by airborne EM and airborne magnetic surveys, some recent diamond discoveries have been in areas without such indicators, or at depths too great for airborne detection. MT and AMT have been shown to be cost-effective methods for detecting not only the tectonic faults that promote the creation of kimberlite pipes, but the conductivity contrast of the pipes, which increases with depth.
Russian companies have made great strides in recent years in the use of MT and AMT in diamond exploration. Surveys have been carried out in the Yakutian diamond province and in the Arkhangelsk Region, where the rapid-reconnaissance 3-H AMT method revealed the second of the only two new kimberlite discoveries since Soviet times.
Alan G. Jones of the Geological Survey of Canada has prepared a presentation on Imaging the Geometry and Structure of Kimberlite Pipes using Audio-MT. Diamond exploration MT/AMT is used around the world by our clients.
Deep Rapid Reconnaissance and Detailed Follow-Up
From near-surface down to any practical drilling depth and beyond, MT allows rapid reconnaissance of areas as large as tens of square kilometers, while detecting conductive zones to 2000 m and deeper.
Closely spaced stations along lines or nets provide data redundancy, high lateral resolution, and a continuous picture of the subsurface resistivity structure.
In a two-pass methodology, station and line spacing are as wide as possible in the first pass to keep cost to a minimum. Once areas of interest have been identified, a second pass with more stations at closer spacing increases resolution. The result is rapid, accurate, and cost-effective identification of conductive mineralized zones.
Rapid, Cost-Effective Mapping Of Conductive Zones
Equipment weighs only 30 kg per site, so it's portable by backpack, ATV, snowmobile, or helicopter, from tundra to jungle, in any season. This logistic simplicity reduces cost and increases productivity.
The small footprint and environmentally benign installation make the technique practical almost anywhere.
Flexible site location and offline sensitivity allow meaningful profiles to be constructed without the rigid grid of methods like seismic and IP.
Induction vectors indicate the direction and relative strength of offline conductors and are especially useful where the surface is resistive or frozen (no electrodes required).
MT/AMT sees through the thick conductive clay (impenetrable by airborne or other surface techniques) that covers many prospective areas.
