The Research On The Methods Analyzing The Characteristics Of Aeromagnetic Anomalies

Magnetic prospecting contains ground magnetic surveys, airborne magnetic surveys,satellite magnetic measurements, marine magnetic surveys and borehole magnetic surveys. Asone of the main methods in magnetic prospectings, aerial magnetic survey was firstlyemployed in searching for magnetite, sulfide and igneous rock deposits, drawing the buriedigneous rock, detecting the oil and gas, geological mappings, and determining geologicalstructures in different conceivable scales. With the improvement of the accuracy inaeromagnetic surveys, more and more geological problems could be solved.Up to now, many works had been done in the field of the analysis of the characteristicsof aeromagnetic anomalies. Among these early studies, most of them focused on thephenomological descriptions of the characteristics of aeromagnetic anomalies,but very fewcan be found concerning the systematic theoretical studies. In this paper, we summarize thekey points of aeromagnetic anomalies characteristicsaccording to the function perspective,and, based on the plane and the vertical characteristics, we reviewthe methods of analysis ofaeromagnetic anomalies. The plane features include the variation of the amplitude andderivative. The derivative features include the total horizontal derivative, the vertical firstderivative and the analytic signal amplitude. The vertical features mainly refers to theanalysisof the cross-section features of different planes. A set of models is designed to test the validityand the accuracy of those methods. It is showed that the amplitude of magnetic anomalies canreflect the strength, the depth and thickness and size of the magnetic body. The derivativefeatures can reflect the extended length and direction of the magnetic body. As the heightincreases, the amplitude of the abnormal decrease, the positions of the total horizontalderivative maxima deviate from the boundary of the model, the ranges of the vertical firstderivative of the zero line become large, the position of the analytic signal amplitude maximamove from the model body boundary position to the center position.In order to test the application results of aeromagnetic anomalies analysis methods. TheChina’s land aeromagnetic T reduction and upward10km anomalies datum is processed, and the characteristics of its planar and vertical features is discussed. It is shown that thenorthern and eastern regions in China are the positive magnetic anomalies zone, the amplitudeand the gradient anomalies change dramatically, the abnormal strike of the northern region isNW, NWW, NE direction, the eastern region is NE, NNE direction. The western region is thenegative magnetic anomalies zone, the amplitude and the gradient anomalies change smoothly,the abnormal strike of the western region is NW, NWW direction. The General characteristicsof aeromagnetic anomalies is " the anomalies features of the northern and southern areribbon" and " the anomalies features of the eastern and western regions are massive ", takingthe West Kunlun-Altun-Yin Mountain and Helan-Dragon-Kangdian as boundaries, theChinese abnormal areas can be divided into the northern, eastern and western anomalies areas,the spatial distribution of abnormal boundaries lines is displayed the "Ding" shaped structure.