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This study presents a software tool Grav3CH_inv developed to estimate the three-dimensional depth structure of sedimentary basins from their gravity data through an iterative process. The algorithm linked to the developed code operates recursively both in the wavenumber domain and in the space domain based on a triple method combination. The modelling strategy allows considerations of the model space with an exponential increase in density with depth and also with density variations in the horizontal direction. The accuracy of computation of gravity anomalies in the FFT-based forward procedure is also increased by using the shift-sampling technique which minimizes discretization effects during transformations between the space and wavenumber domains. Given the observed gravity anomalies and the density design of the basin, the iterative procedure performs automatically until the goodness of the fit between the observed and modeled anomaly, either the root-mean-square error or the largest error is below its pre-assigned value. As an advantage, the computing time is acceptably short for such a kind of an modelling problem. The GUI-enabled interactive control functions of the Grav3CH_inv code allow users to set optional settings, style of outputs and export formats, and facilitate operations without requiring coding expertise to perform the relevant procedures of the algorithm. The feasibility and accuracy of the proposed software is demonstrated by evaluating the synthetically produced gravity anomalies of various 3D basin models and also by analyzing an actual gravity data from the Los Angeles basin, California.

This paper presents a MATLAB based program, including an easy-to-use graphical interface, developed to estimate 3D geometry of magnetic basement interfaces from respective gridded magnetic anomalies by a rapid iterative procedure. The developed code uses an algorithm based on a relationship between the Fourier transforms of the magnetic data and the interface topography. Given the average depth to the magnetic interface and parameters related to the magnetization, the iterative procedure built up in the frequency domain results with accurate depth estimates in a very short computing time. The program is capable of handling large data sets. The convergence in the iterative process is improved by incorporating a high-cut filtering. The iterations stop when either the RMS error between two successive approximations at any step of the iteration has increased relative to the previous step or when the RMS is below a predefined threshold value, or after a specified maximum iterations number. Settings and updating of the input parameters as well as displaying and exporting the interpretation outputs can easily be managed with the interactive control skills supported by the graphical user interface (GUI) of the MagB_inv code. Applicability and efficacy of the algorithm are illustrated on synthetic data from three 3D interface models, the respective inverted depths match the actual depths even in the presence of noise. As a practical example, the algorithm was also applied to observed anomalies of the total magnetic field from NW-Germany. The calculated magnetic basement interface from the real data application is in good agreement with the previously published configurations of the basement of this study area.

There is a need, within both geophysical exploration and deep geophysical research, to estimate magnetic basement depth. Forward and inverse modeling studies to map the basement depth are commonly used within petroleum geophysics. To obtain the basement topography, modeling studies are made of the 2D profile data or 3D map data. In this study, a different algorithm was introduced to estimate the magnetic basement depth from map data. The algorithm is based on the analytical solution of exponential equations obtained from Fourier transformation of magnetic data. This algorithm has been tested on synthetic magnetic anomalies originated from multi-prisms. Following encouraging test results, the proposed algorithm was also tested on field data. The depths obtained from the proposed approach were satisfactory in comparison with the depths obtained from seismic survey cross-sections and boreholes. Basic MATLAB code is included in the Appendix.