Magnetotellurics surveys
Abitibi Geophysics is now offering Magnetotellurics (MT), Audio-frequency MT (AMT), and Controlled Source Audio Magnetotellurics (CSAMT) Surveys in partnership with Zonge International.
These surveys and imaging techniques measure magnetotelluric signals on the earth’s surface to map geologic structures at depth. MT and AMT use naturally occurring ionospheric current sheets and lightning storms as a source, measured through grounded dipoles and magnetic field antennas. CSAMT uses a controlled source, rather than a natural source, making it effective in most regions. This resistivity sounding technique provides critical information about geological structure and lithology. Modelled data can be presented as cross sections, plan views, fence diagrams, or 3D diagrams.
Applications in Mineral Exploration
- Identification of systems that produce conductive metals such as copper, gold, silver, lithium, and uranium.
- Mapping of geological structures and features such as faults, fractures, and folds.
- Planning of drilling programs by providing information about the depth and location of potential mineral deposits, which can reduce exploration costs.
- Estimating the size and quality of mineral deposits and assessing their economic viability by combining CSAMT data with geological and geochemical data.
- Investigation of deep structures—from 50 m to several kilometers—providing much deeper information than other resistivity methods.
- Mapping in the 50 m to several tens of kilometers depth range.
- Resistivity is influenced by rock or sediment porosity, pore fluids, and the presence of certain mineral assemblages.
Execution (CSAMT)
- Current injection length: 1–2 km
- Transmitter located 3–5 km from the survey area
- Several receiver stations read simultaneously
- Multiple spreads combined to complete the profile line
Find out more by readint this case study on mapping of closed-basin lithium-bearing brines using Magnetotellurics.
