Structural Characteristics Of Wanquan-Huairou Area Based On Gravity And Magnetic Data

The Wanquan-huairou area is located at the intersection of Inner Mongolia uplift belt,Yanshan platform fold belt and Shanxi uplift belt,with a total area of about 28700 km~2.Since Archean,the area has experienced multiple periods of tectonic movement,and developed intermountain basins,such as Zhangxuan,Huaizhuo,Yanfan,Yangyuan.The area is rich in gold and other mineral resources in Chongli-Xuanhua-Chicheng area.The predecessors have carried out certain field geological work in the Wanquan-Huairou area,and developed some electrical and seismic explorations for the Zhangjiakou fault in the area,and also achieved some structural geological and mineral geological research results within a certain area.However;there is a lack of systematic research on the overall structure and mineral geology of the area.Based on 1:200,000 gravity and magnetic data,the paper systematically studies the structural characteristics of the study area in combination with geological and other geophysical data,and comprehensively predicts the gold deposits prospecting area in this area.In this paper,the gravity and magnetic fields are separated by potential field separation methods such as Analytical continuation and Moving-average filtering,and residual gravity and magnetic anomalies are obtained,and their causes are qualitatively explained based on geological data.The fault tectonic system of the study area was speculated and determined by using the characteristics of gravity and magnetic field and other potential field edge identification methods,such as the normalized total horizontal derivative vertical derivative(NVDRTHDR),vertical second derivative,total horizontal derivative;Constrained by electrical method,seismic data and borehole data,the four gravity anomaly profiles passing through the main basins in the study area were fitted,and the development characteristics of the main basins in the area were analyzed;The relationship between the distribution of the proven gold deposits and the characteristics of gravity and magnetic fields is discussed and analyzed,and the prospective areas of gold deposits in the study area are predicted by using the characteristics of gravity and magnetic fields in combination with mineralization factors.The research results show that the high gravity area and the low gravity area in the Wanquan-Huairou area are mainly caused by the uplift and depression of the basement,and are also affected by high-density and low-density magmatic rocks.The metamorphic rock basement and strong magnetic magmatic rocks are the main factors for the high magnetic force.The faults trends in the study area are mainly EW,NW and NE trending,and the NEtrending faults cut the NW-trending faults.The boundaries of Mesozoic and Cenozoic Basins,such as Zhangxuan,Huaizhuo,Yanfan,Yangyuan are controlled by basin margin faults,and the basement depth is between 500 and 1000m.Most of the gold deposits(points)developed in the study area are located near the edges and faults with low gravity areas and high magnetic areas.In Archaean and Proterozoic,magmatic rocks intruded into such areas with strong tectonic activities and developed faults,which are conducive to the formation of gold deposits.These characteristics of gravity and magnetic fields can provide certain indications for the prediction of gold deposits.There are two metallogenic prospective areas in the study area,such as in Huaian Miyun-Huairou.