Research On Low-altitude Aeromagnetic System And Its Application In Duobaoshan Area

Magnetic prospecting is the most widely used geophysical method in geological and mineral exploration,it is one of earliest technical means of application geophysical methods with the lowest cost,most mature and most efficient.Although traditional magnetic prospecting has relatively low resolution,since the 1990 s,with the improvement of the accuracy of measuring instruments,magnetic prospecting technology has entered a new stage of high-resolution exploration,especially the development of the aviation magnetic prospecting which is the most rapidly,aeromagnetic prospecting has become an important technical measure in basic geological surveys such as land and natural resources surveys and evaluations,and oil and gas mineral surveys.At present,the main aeromagnetic flight platforms in China include fixed-wing aircraft flight platform,helicopter flight platform,unmanned aerial vehicle(uav)flight platform,hot-air balloon flight platform,powered glider flight platform,and airship flight platforms,etc.Among them,the powered glider flight platform has the characteristics of strong applicability,high working speed,and appropriate reduction of surface man-made magnetic interference.In recent years,it has become a convenient,rapid,practical and effective method for aeromagnetic measurement.The forest swamps in the Duobaoshan area of Heilongjiang Province are covered with heavy accumulations and the topography has a high elevation difference.This is a typical hilly area,and there are certain surface human disturbances in the Duobaoshan area.Therefore,it is difficult to carry out ground geology and geophysics work in this area.The major minerals in the Duobaoshan area are dominated by large-scale porphyry copper deposits and skarn copper deposits.The results of physical measurements in this area indicate that the magnetic properties of iron ore are the highest;the magnetic properties of neutral intrusive rocks are high;and the intermediate-acidic intrusive rocks are slightly lower.The magnetic properties of volcanic sedimentary rocks and volcanic rocks are relatively weak,and the range of magnetic anomaly changes is very large.The magnetic properties of porphyry copper ores are very weak,and there is almost no reflection of magnetic anomalies.It is not easy to find copper bodies directly through magnetic anomalies of using the high-precision,high-resolution,low-level magnetic survey system of the powered glider to works in this area,but for the orecontrolling factors of copper ore body: the ore-forming parent rock body is controlled by the ore-bearing structure,and it is endowed with fracture development sites,intersecting each other,and cutting each other.These factors are manifested in the magnetic field measurement.Therefore,by distinguishing and searching for oreforming rock bodies and veins,determining the ore-controlling structures and combining the volcanic rocks and sedimentary rocks in the ore bodies,it is possible to analyze the target areas or spaces that are likely to be ore-forming.This paper systematically studies low-altitude and high-precision aeromagnetic systems,and uses the low-level aeromagnetic data from the Beijing Geology and Mineral Research Institute in the field survey in 2013 in the Duobaoshan area of Heilongjiang to explain and combine relevant geological and geophysics data.The specific results are as follows:(1)The low-altitude magnetic survey system of power glider and its field work method were systematically introduced in this paper.(2)This paper confirms the accuracy of low-altitude aeromagnetic data and the advantages of low-altitude aeromagnetic systems by comparing low-level aeromagnetic data with previous large aircraft aeromagnetic and ground magnetic data.(3)In this paper,the low-altitude aeromagnetic data in the Duobaoshan area are subjected to pole processing,gradient processing,and anomalous three-dimensional inversion,etc.The distribution range of the magnetic base and the metallogenic structure of the mining area are determined,and predictions of metallogenic prospective area in the surrounding area are made.(4)Combining the previous geological and geophysical work conditions,and based on the processing results of low-altitude aeromagnetic data,this paper summarizes the methods of indirect prospecting for low-altitude aeromagnetic systems,and proposes suggestions for external secondary prospecting in the future.