渤海湾地区壳幔结构重磁综合研究

渤海湾盆地是华北克拉通破坏的中心,其东部渤海海域深部结构研究对认识华北克拉通破坏范围及动力学过程具有重要意义.为此,本文选取自河北新城经天津静海沿东南方向进入渤海海域的剖面进行重磁反演,研究其地壳结构特征.通过对该地区文献调研及2010年渤海海陆联测初步结果建立初始模型,结合本地区密度、磁化率特征进行二度半体重磁异常反...

Crustal and mantle structure of the Bohai bay area based on the gravity and magnetic data

Bohai bay basin is the center area of the destruction of North China Craton (NCC). The deep structure study of the Bohai Sea plays a key role in understanding the scope and dynamic process of the destruction of NCC. In this paper, we studied the crustal structure of the profile from Xincheng, Jinghai, to Bohai sea along the southeast direction based on the gravity and magnetic data. The initial model was build based on the former studies about the sedimentary structure, deep crustal structure and the onshore-offshore seismic survey in 2010. Combined with the density and magnetic susceptibility parameters in this area, the crustal structure and the physical parameter distribution were inverted using 2.5D gravity and magnetic inversion method. The integrated study indicates that the Moho becomes shallower from the land to the sea. The Moho of the Bohai sea is shallower, and rises locally in Shaleitian area with about 2 km uplift. The variation of the Moho is similar with the lithosphere thinning in the eastern NCC. It reflects that lithosphere and deep crustal structure were similarly affected by the destruction of the NCC from Mesozoic. We do the deep uplifting modeling to test the gravity effects from the mantle uplifting. Combined with the analysis of the gravity of the profile, it is less likely to have mantle plume or large mantle uplifting in the Bohai sea, the local small uplifting of the Moho in Bohai sea is likely related with a small anomaly body in the upper mantle.