Constrained 3D inversion of magnetic data with structural orientation and borehole lithology: A case study in the Macheng iron deposit, Hebei, China

Abstract

We have developed a case study on the use of constrained inversion of magnetic data for recovering ore bodies quantitatively in the Macheng iron deposit, China. The inversion is constrained by the structural orientation and the borehole lithology in the presence of high magnetic susceptibility and strong remanent magnetization. Either the self-demagnetization effect caused by high susceptibility or strong remanent magnetization would lead to an unknown total magnetization direction. Here, we chose inversion of amplitude data that indicate low sensitivity to the direction of magnetization of the sources when constructing the underground model of effective susceptibility. To reduce the errors that arise when treating the total-field anomaly as the projection of an anomalous field vector in the direction of the geomagnetic reference field, we develop an equivalent source technique to calculate the amplitude data from the total-field anomaly. This equivalent source technique is based on the acquisition of the total-field anomaly, which uses the total-field intensity minus the magnitude of the reference field. We first design a synthetic model from a simplified real case to test the new approach, involving the amplitude data calculation and the constrained amplitude inversion. Then, we apply this approach to the real data. The results indicate that the structural orientation and borehole susceptibility bounds are compatible with each other and are able to improve the quality of the recovered model to obtain the distribution of ore bodies quantitatively and effectively.

Development of a Hybrid Fixed-Wing UAV Aeromagnetic Survey System and an Application Study in Chating Deposit

“…However, it has faced two major challenges: the problem of multiple solutions and the problem of computation time. Scholars have addressed these two issues by imposing additional constraints to constrain the inversion process and by carrying out deep research and applying optimizing inversion algorithms and using multi-core parallel technology to improve computation speed [30][31][32][33][34][35][36][37][38][39][40][41][42][43].…”

“…inversion algorithms and using multi-core parallel technology to improve computation speed [30][31][32][33][34][35][36][37][38][39][40][41][42][43].…”

Inversion of high-amplitude magnetic total field anomaly: an application to the Mengku iron-ore deposit, northwest China

“…Such a big error (3,945 nT) has a deep negative impact on the interpretation and even absolutely mistake. The error between Δ T pro and Δ T true should be considered carefully when the data indicate high magnetic amplitudes 30 . To understand the difference between Δ T pro and Δ T true , we converted the magnetic anomalies to reduction to the pole (RTP) values for m = 50 A/m (Fig.…”

“…Coleman and Li 29 studied the difference between the errors of the total-field anomaly and magnetic amplitude data and found that the errors in the three orthogonal components converted from the total-field anomaly had similar standard deviations. Based on the total magnetic anomaly is no longer approximately equal to projection anomaly in the highly magnetic environments, Sun et al 30 used the information from the borehole data and structural orientation as constraints and get an acceptable result. In our study, we define the error between projection anomaly and observed modulus difference anomaly firstly and carefully discuss the error caused by amplitude, inclination and declination individually and together between the projection anomaly results (data processing, inversion and interpretation) with those of the modulus difference anomaly for strong magnetic anomalies.…”

A Constrained Approach by Curie Point Depth Estimation for the 3‐D Inversion of Regional Lithospheric Magnetic Anomaly Data in Spherical Coordinates and Its Application to the Northern Xinjiang, China

“…As for the second problem, the 3-D inversion method in which the CPD is incorporated in a geocentric SCS, can be addressed by the development of the inversion methods and their corresponding approaches with integrating geophysical and geological information in the CCS (e.g., Lelièvre & Oldenburg, 2009a;Li & Oldenburg, 1996Pilkington, 1997;Sun et al, 2019). Du et al (2013Du et al ( , 2014 applied a 3-D inversion approach in SCS to the magnetic data over Australia.…”