Principle And Application of The WCZ-3 Proton Magnetometer

Principle and Application of the WCZ-3 Proton Magnetometer

Principle

The observation of the geomagnetic field, apart from the changing magnetic field, is primarily composed of the normal field originating from within the Earth and the anomalous field generated by various geological formations within the Earth's crust. Magnetic exploration utilizes magnetometer data to identify these anomalies, aiming to address geological inquiries and facilitate mineral exploration. The advent of the proton magnetometer, owing to its high precision, operates on a different principle compared to other magnetometers, enabling high-resolution and precise measurements of weak magnetic materials such as the Earth's magnetic field.

The working principle of the WCZ-1 proton magnetometer is based on measuring the precession of hydrogen protons in a magnetic field. The sensor is filled with liquid containing hydrogen, where the protons are in a random arrangement before being polarized. Upon applying a polarization signal, the protons begin to precess. As the polarization signal diminishes, the precession of the protons is gradually influenced by the external magnetic field. By measuring the frequency changes within the sensor, the magnitude of the external magnetic field can be determined. This process can be continuously repeated to sustain measurements.

Application

Using the application of the WCZ-3 proton magnetometer in a mining area in Chongqing, China, we can illustrate the application of high-precision magnetic exploration in mineral prospecting. The site is located approximately 22 kilometers away in a region characterized by medium to low hills and ridges. The main ridges extend in a northwest direction, with higher elevations to the northwest and lower elevations to the southeast. The highest altitude reaches 1,282.9 meters, while the lowest is at 965 meters, resulting in a relative elevation difference of about 317.9 meters. In order to assess the development prospects of an iron ore deposit, a comprehensive understanding of the iron ore resources in the area was sought, including preliminary insights into the mineralization within the ore body and its potential extraction sites, aiming to identify an exploitable iron ore deposit as early as possible. In accordance with geological survey requirements, high-precision magnetic survey work was carried out in the mining area. Considering the characteristics of the surveyed area, we established 10 survey lines oriented at 135 degrees, with spacing set at 100 meters between lines and 10 meters between points, adhering to a scale of 1:10,000.

Equipment Used

• WCZ-1/3 Proton Magnetometer

Result 

The area located to the south of the ore deposit is a low-lying area, consisting of an alluvial and fluvial-terrace deposit primarily composed of clay and sandy gravel. The overall geological formation within the ore deposit exhibits a monocline structure trending northeast to southwest, with predominant fault structures oriented in a northeast direction, forming part of the Inedian volcanic system. Among these, the prominent F1 fault trends approximately 40 degrees with a dip of 50 degrees, serving as the primary ore-controlling structure in the region. Intense magmatic activity is evident within the area, with exposure of early Yanshan fine-grained biotite granite (γ52(3)c) to the south of the ore deposit, a component of the Baliao granite body, providing a source of hydrothermal fluids for the formation of iron polymetallic deposits within the region. Surrounding rock alteration within the ore deposit mainly includes hematization, limonitization, magnetitization, lead-zinc mineralization, and silicification. The genesis of this ore deposit belongs to the hydrothermal metasomatic type.

Magnetic anomaly profile and interpretation for a specific line.

Magnetic anomaly plane contour map