Comparison of a low‐cost magneto‐inductive magnetometer with a proton magnetometer: a case study on the Galali iron ore deposit in western Iran

Abstract

A B S T R A C TThe proton magnetometers, also known as the proton precession magnetometers, are among the most widely used instruments for magnetometry surveys, owing to their high resolution which is about 0.01 nT. As the economically attractive ferromagnetic deposits generate a magnetic field anomaly which exceeds 100 nT, this resolution is not needed for detecting such large signals. The recently introduced magneto-inductive technology has led to the development of a low-cost magnetometer that can measure the ground magnetic field up to a resolution of around 10 nT. These magnetometers are inexpensive, come in a very small size, and are lightweight compared to the more common magnetometers such as the proton precession type. In this research, a low-cost magneto-inductive sensor and a highly precise proton magnetometer are simultaneously utilized at the same profiles on the Galali iron ore deposit in the northwest of Iran. The discrepancy of two measurements is less than 400 nT, often less than 100 nT, while the changes in the total magnetic field on this anomaly are around 7500 nT, which is 11 times larger than the maximum difference between the two measurements. In addition, the value of the regression coefficient between the two measurements for all profiles is more than 0.97. Also, the slope of the fitted line for the two measurements for all profiles is close to one. These results demonstrate the applicability of the new low-cost magneto-inductive sensor in magnetic prospecting.

Developing a low-cost frequency-domain electromagnetic induction instrument

“…These tools have the potential to be leveraged in purpose-built low-cost geophysical equipment that can acquire data without exceeding the durability and budgetary constraints for many types of near-surface geophysical investigations. Examples following this low-cost instrumentation approach include direct-current (DC) resistivity (Clark et al, 2016;Ahmad et al, 2019;Sirota et al, 2021), seismic nodes (Dean et al, 2017;Soler-Llorens et al, 2019;Wilson et al, 2021), and magnetometers (Schofield et al, 2012;Shahsavani, 2018), each of which has demonstrated the possibility of acquiring data of comparable quality to commercial grade systems. While such home-grown instrumentation is neither as robust nor as likely to have fully in-built safety factors as commercial-grade instruments, it can lower the barrier-to-entry for many users, enable enthusiast, academic, or humanitarian geoscience applications, and be used to develop low-cost geophysical networks for timelapse monitoring projects.…”