Can Targeted Source Information Be Extracted From Superimposed Magnetic Anomalies?

Abstract

Magnetic anomalies commonly contain anomalies generated by crustal rocks that have variable mineral compositions and natural remanent magnetizations. Recovery of magnetic parameters from superimposed magnetic anomaly sources is therefore important for mineral exploration and geological studies. Superposition of magnetic anomalies leads to nonnegligible errors of inversion and interpretation. Therefore, extraction of magnetic anomalies is essential for magnetic data processing; however, existing methods cannot extract magnetic anomalies caused by sources without substantial depth differences. A novel low‐rank method is proposed for extracting a target magnetic anomaly from a superimposed anomaly. The low‐rank feature of the magnetic anomaly is used to obtain the target anomaly by reducing the Schatten‐p norm of the superimposed anomaly according to the possible target source distribution. The target magnetic anomaly can then be extracted from the data generated by the source interference at the same or different depths. The accuracy of the proposed method was verified using synthetic modeling. Magnetization vector information for individual igneous rocks was recovered from extracted magnetic anomalies via 3‐D inversion of field data from Yeshan (eastern China) that contain complex magnetic anomaly superpositions. The distributions and lithologies of five buried igneous rocks, including basalt, diabase, and granodiorite, were then identified. The proposed method expands the problem of separating magnetic information from rocks in different layers with large depth differences to rocks within the same or other layers and recovers geometric and physical information for each targeted magnetic source from the superimposed anomaly.

Study on Geothermal Genesis Mechanism and Model in the Western Margin of Ordos Basin

“…In this research, to study the deep interface in the study region, we measured aeromagnetic data and calculated the depth of the Curie isotherm and geothermal gradient, as shown in Figure 3. Figure 3a shows the distribution of aeromagnetic pole anomaly in the study area, which is jointly caused by shallow magnetic rocks and deep magnetic interfaces, and the superimposed magnetic anomaly needs to be separated and extracted [37,38]. The Curie isotherm surface can be estimated by using the aeromagnetic anomaly without the influence of shallow field sources (Figure 3b).…”