Comparison and Application of Extraction Methods for Aeromagnetic Anomaly Caused by Deep Magnetite: A Case Study of the Qihe-Yucheng Ore Area, Shandong

doi:10.19657/j.geoscience.1000-8527.2024.004

Abstract

Abstract:

The large depth that the magnetite is buried and the long distance of aeromagnetic survey always leads to a weak signal of magnetic anomaly.In addition, due to that the deep magnetite mostly is formed through contact metasomatism caused by magmatic intrusion, the magnetic anomalies sourced from the source rocks and orebodies are always coupled and interfered with each other.This is challenging to directly delineate the target area for the deep magnetite orebody from the original map of aeromagnetic anomaly.Previous studies show that potential field separation technology is an effective approach to extract ore-caused anomalies.However, there are many potential field separation methods and they are all different, in terms of operation convenience and different results of extraction.In this paper, we systematically compared and analyzed the convenience of six commonly used separation methods, and evaluated the effects of extracting ore-caused anomalies from both the whole and target regions.Consequently, we established the theoretical model and verified the feasibility extracting the deep ore-caused anomalies based on the geologic background of the Qihe area, Shandong.At the end, we recommend using the marker profile line to verify the extraction effect of ore-induced anomalies when the measured data were processed.The ore-caused anomalies extracted agree with the known drilling data, indicating a strong correlation between the extracted and realistic anomalies.This study provides a reference for future delineation of target ore fields and laying-out of drilling locations.

Key words: sinoprobe, magnetite, aeromagnetic survey, potential field separation, delineation of target areas

CLC Number:

P318.63

GAO Xiuhe, YU Changchun, LI Xingsu, GE Tengfei, HE Jingzi. Comparison and Application of Extraction Methods for Aeromagnetic Anomaly Caused by Deep Magnetite: A Case Study of the Qihe-Yucheng Ore Area, Shandong[J]. Geoscience, 2024, 38(01): 25-34.

Figures/Tables 13

Fig.1 Schematic diagram of the method showing removing the upward continuation field filter

Fig.2 Schematic diagram of the method showing high pass filter

Fig.3 Schematic diagram of the method showing matched filter

Fig.4 Diagrams of the theoretical model and forward magnetic anomaly (h=200 m)

Fig.5 Diagram of the regional field obtained by potential field separation

Fig.6 Diagram of the local field obtained by potential field separation

Fig.7 Diagram of main profile showing the ore-caused anomalies in the east-west direction

Table 1 Errors of ore-caused anomalies for all extraction methods (RMSE)

	去延拓场法	高通滤波法	匹配滤波法	算术平均法	高斯平滑法	插值切割法
全区	12.7131	5.7175	5.0571	5.4365	5.7794	5.6875
靶区	29.7301	4.4138	5.2610	4.5814	5.4659	5.7606

Fig.8 Diagrams of aeromagnetic data measured in the Qihe area and the results of reduction to pole

Fig.9 Diagrams of regional field obtained by the potential field separation in the Qihe area

Fig.10 Local field of ore-caused anomalies obtained by potential field separation in the Qihe area

Fig.11 Profile diagrams of ore-caused anomalies in the potential field separation area of aeromagnetic data measured in the Qihe area

Fig.12 Schematic diagrams of ore-caused anomalies in the Litun area and the drilling positions

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