Study On Influencing Factors Of Field Source Edge Enhancement Methods Based On Magnetic Anomalies

Magnetic exploration is an important geophysical exploration method for geological structure research and mineral resources investigation,and the processing and interpretation of magnetic anomalies are the basis of the above-mentioned methods.Among them,the identification of field source boundary based on magnetic anomaly is an important part of the processing and interpretation of magnetic anomaly data,which is of great significance to the actual delineation of anomalies.In the actual production of magnetic exploration,due to the influence of network layout,source burial depth,oblique magnetization and noise,the field source boundary recognition technology based on magnetic anomaly can not directly and accurately identify the field source boundary.Therefore,many field source boundary enhancement methods have been studied by predecessors in order to enhance the field source boundary recognition ability.These methods include statistical numerical characteristics(such as NSTD)based on numerical analysis,and boundary features(such as TA)enhanced by derivatives.Although they are effective for theoretical models,they may not be applicable in practical work.For example,the actual production network is sparse than the theoretical model network,the observation data contains fewer details than the theoretical data and there is noise in it.In the case of these problems,the effectiveness of the field source boundary enhancement method based on magnetic anomaly needs to be tested.In this paper,the boundary enhancement methods proposed in recent years are sorted out,12 commonly used methods are selected for comparative analysis.A more practical model is designed to explore the factors affecting the boundary enhancement methods.The advantages and disadvantages of these methods under different field source characteristics and different measurement conditions are summarized,which provides a reference for the selection of methods for demarcating the boundary of magnetic anomalies in practical production.In this paper,it is considered that reduction-to-the-pole can improve the calibration ability of various boundary enhancement methods.If the geological data of the work area is insufficient and the reduction-to-the-pole parameters are unknown,a slightly larger magnetic dip reduction-to-the-pole can be selected,and better boundary enhancement effect can be obtained than that of the non-reduction-to-the-pole method.Under the influence of many factors,the THD,Theta map and the NSTD method have strong applicability and can be combined to calibrate the boundary position of field source.