利用重力数据反演中国东海海域莫霍面深度

Moho Depth of the East China Sea Inversed Using Gravity Data

  • 摘要: 莫霍面是地壳与上地幔的分界面,莫霍面的研究有助于认识地球深部构造及演化。在以往的研究中,由于重力反演方法、使用资料不同,中国东海海域莫霍面深度反演结果有较大不确定性。通过收集中国东海海域高精度地形和自由空气重力异常数据,计算了布格重力异常并分析了其构造特征。提取了中国福建省大田至中国台湾省花莲剖面和中国东海陆架盆地至菲律宾海盆剖面的重力异常数据,采用人机交互正演、反演拟合技术得到了这两条剖面的地壳密度与莫霍面深度。通过向上延拓的方法提取了莫霍面所引起的重力异常,在两条剖面反演结果和地震探测结果的约束下进行Parker-Oldenburg界面反演,得到了该地区的莫霍面深度。反演结果显示,中国东海海域莫霍面深度的变化范围为-34.4~-8.8 km,其结构呈两凹两凸的特征。

     

    Abstract: The Moho surface is the interface between the crust and the upper mantle. The study of the Moho surface is helpful to understand the deep tectonic evolution of the Earth. In previous studies, due to the different gravity inversion methods and data used, the depth inversion results of the Moho surface in the East China Sea are uncertain. High-precision terrain and freeair gravity anomaly data are collected in the East China Sea, the Bouguer gravity anomaly is calculated, and the Bouguer gravity anomaly characteristics are analyzed. The gravitational anomaly data of the two profiles, which are Datian Fujian China to Hualian Taiwan China profile and the East China Sea Shelf Basin to the Philippine Basin profile, are extracted. The crust density and the Moho depth of the two profiles are obtained by human-machine interaction forward and inversion fitting technique. The gravity anomaly caused by the Moho surface is extracted by the upward continuation. The Parker-Oldenburg interface inversion is performed under the constraint of the two profiles inversion results and the seismic detection results to obtain the Moho depth in the area. The inversion results show that the Moho depth in the East China Sea has a variation range of -34.4~-8.8 km, whose structure is characterized by two concave and two convex.

     

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