Estimating total magnetization direction of magnetic sources by using airborne vector magnetic data

Estimating total magnetization direction plays an important role in data processing, inversion and interpretation for magnetic sources with strong remanence and self demagnetization effect. Compared with traditional aeromagnetic total-field survey, airborne vector magnetic survey can measure vector magnetic information. Based on the integral relationship between the first order moment of the three-component magnetic anomalies and the magnetic moment of magnetic sources, we presented the total magnetization direction estimation method of magnetic sources by using airborne vector magnetic data. The method is easy to be affected by adjacent anomalies, which makes it difficult to obtain the center of magnetic sources. We analyzed the location relationship between the estimated magnetization direction and the center of magnetic sources with different inclinations, and then limited the estimation area to estimate the direction for multiple anomalies. The method was applied to the airborne vector magnetic data measured at the Qixin area of the East Tianshan Mountains in China and the total magnetization direction of the Qixin Rock with strong remanent magnetization was estimated. The estimated direction was applied to the process of reduction to the pole (RTP). The RTP result shows that the asymmetry of magnetic anomalies caused by the oblique magnetization is well-eliminated and the result is similar to magnetic amplitude data. The estimated direction can be regarded as the uniform total magnetization direction, assuming the direction does not vary greatly within the magnetic sources. The method is significant to data processing, inversion and interpretation of magnetic anomalies caused by strong remanence.