Gravity anomalies and crustal density structure characteristics of profile Tai'an-Zhucheng

The high-precision gravity observation profile of Tai'an-Zhucheng, located in the east part of the East China Craton, is an important tectonic zone in eastern China and an important area of seismic activity. The gravity anomaly of the profile is obtained by using the data of relative gravity joint measurement and GNSS three-dimensional coordinate measurement at the same site. Combined with the results of regional Bouguer gravity field, deep earth exploration and geological structure, density structure inversion and residual density correlation imaging studies were performed on the profiles. The results show that the anomalous variation of the profile Bouguer ranges from (-30.1 to 7.3) x 10(-5) m.s(-2), with an overall rising trend from west to east. From Tai'an to Yiyuan, the low background rises gently and gradually with the elevation of the corresponding position showing a "synchronous" change. From Mazhan to Zhangjialou, the high background gradually rises and the topographic elevation shows a "mirror image" change. The turning point of high-low anomaly background is about 150 km in the western part of Yishu Fault Zone. The background anomaly is a response to the change of crustal thickness, and the overall pattern is deep in the west and shallow in the east. The crustal thickness rise in the Yimu Fracture Zone is probably due to the extrusion and expansion of the crust when the crust and lower mantle material invades upward along the fracture. The crustal density of the profile shows three layers of structure: upper, middle and lower. There are low-density bodies in the middle and upper crust in the western part of Luxi Uplift and Yishu Fault Zone, which may be caused by the upwelling rocks of upper mantle material containing part of high-temperature fluid and molten rock mass. The crustal structure in the Jiaodong area is relatively intact and homogeneous, which reflects that the crustal activity in the Jiaodong area is not strong. Bouguer gravity anomalies and variations in residual density can be seen at the locations of the major fracture zones in the section. This may be caused by the fractures controlling the development of the subsurface medium. The profile density model shows segmental characteristics of subsurface density and deep and shallow tectonic differences. The Yishu Fault Zone is the demarcation zone between the Luxi Uplift and the Jiaodong Uplift. In this paper, we investigate the characteristics of the gravity and density structure of the profile Bouguer and analyze the relationship between seismic activity, dynamical background and the density structure of the crust.