A versatile solution for the gravity anomaly of 3D prism-meshed bodies with depth-dependent density contrast

作者：Jiang, Li^*; Zhang, Jianzhong; Feng, Zhibing

来源：Geophysics, 2017, 82(4): G77-G86.

DOI：10.1190/GEO2016-0394.1

• LINEARLY VARYING DENSITY
• RIGHT RECTANGULAR PRISM
• GRAVITATIONAL ATTRACTION
• SEDIMENTARY BASINS
• POLYHEDRAL BODIES
• SINGULARITIES
• FIELD
• INVERSION
• INTERFACE
• ALGORITHM

We have developed a generalized solution for computing the gravity anomalies of 3D irregular-mass bodies with complicated density-contrast variation. The 3D irregular-shaped bodies can be approximated flexibly by a collection of finite-juxtaposed right-rectangular prisms. The complicated density-contrast variation of each prism can be well-represented by a depth-dependent polynomial function. A novel analytic solution of gravity anomalies due to a right-rectangular prism with an arbitrary order of polynomial density-contrast function of depth is then derived. The solution is singularity free in the upper half-space over the prism, and its singularity in the lower half-space containing the prism is resolved by assigning their limit values to the singular terms. The numerical stability of the solution is also evaluated through numerical tests. Hence, the solution can be used to compute the gravity anomalies of 3D irregular bodies with variable density contrasts without singularities when computation points are within the numerical stability range. Based on synthetic models with variable density contrast, our solution is validated by using other solutions in the literature. We also simulated the gravity anomalies of the Los Angeles basin and compared them with the observed anomalies and with those computed using the analytic solutions of other workers. These tests confirm the accuracy and efficiency of our analytic solution.

• 出版日期2017-8
• 单位中国海洋大学