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In mineral exploration, the ores with different magnetic susceptibility can be well delineated by physical property inversion of magnetic data. However, further wide applications of the magnetic inversion method have been seriously restricted by the existence of strong remanence and the computation of large-scale datasets. To solve these two problems, this study innovatively presents an efficient magnetic inversion algorithm in the presence of strong remanence. The weighted data misfit term and regularization term were used to establish the objective function. The detailed related formulas were derived and presented. For numerical computation, the Taylor series approximation was introduced in the objective function to linearize the relationship between the transformed magnetic data and magnetic susceptibility. The objective function was converted to a general Tikhonov form by several matrix transformations. To realize computational efficiency, a fast randomized algorithm was utilized to efficiently solve the Tikhonov problem and to efficiently determine the suitable regularization parameter along with the generalized cross-validation (GCV) method. Comparative tests on synthetic example show the effectiveness and efficiency of the proposed algorithm. The proposed efficient algorithm is successfully applied to two sets of real magnetic data, and the inversion results are verified. [ABSTRACT FROM AUTHOR]

As one of the largest gold deposits in the Liaodong area, northeast of China, the Wulong gold field (WGF) has suffered a severe decline in resource reserves after decades of mining, so it is urgent to explore the deeper unknown orebodies. However, the complex terrain and a large reservoir make it challenging to carry out a complete ground survey in the study area, leading to a lack of first-hand data for geological surveys. Therefore, in this study, aeromagnetic data covering the whole WGF and its adjacent regions are used to depict the distribution of various plutons, distinguish the fault structures, and predict possible orebodies in several gold deposits with their guide for further gold mineral exploration. Fifteen new faults are identified from the lineament enhancement results of the anomalies, and the high magnetic susceptibility of some faults is demonstrated to be due to the shear deformation and dike intrusion of the Wulong pluton. The 3D magnetic inversion results show the spatial location of the Sanguliu pluton and verify that the genesis of the Wulong gold deposit is related to Sanguliu Pluton from the perspective of geophysical models. Further, the inversion results suggest that the depth of concealed orebodies in the Wulong gold deposit, Yangjia gold deposit, and Chengshan gold deposit could be 900, 1500, and 1300 m, respectively. This study deepens the understanding of the mineralization of the WGF, verifies the great exploration potential of the WGF, and provides a geophysical basis for the subsequent prospecting. [ABSTRACT FROM AUTHOR]