TODGINV—A code for optimization of gravity anomalies due to anticlinal and synclinal structures with parabolic density contrast

Abstract

A code, TODGINV, to determine the parameters of 2D anticlinal and synclinal structures besides estimating linear regional gravity background is presented wherein the density contrast varies with depth based on a parabolic equation. The main program, TODGINV, is supported by five subroutines namely GANTCLINE, GSYNCLINE, PDSANT, PDSSYN and NOREQS. Forward modeling is realized through the subroutine GANTCLINE in case of an anticlinal structure while GSYNCLINE in case of a synclinal structure. PDSANT and PDSSYN compute the partial derivatives of anticlinal and synclinal structures, respectively, whereas NOREQS solves the system of normal equations. The efficiency of the code is illustrated with a set of synthetic gravity anomalies over an anticlinal and a synclinal structure both with and without regional background. Further, the code is exemplified with the gravity anomalies of the Pays De Bray anticline, France, and the results are found to be more consistent with borehole information rather than with those of Alessandrello et al. (1983, Automatic three-layer, three-dimensional deconvolution of the Pays De Bray anticline. Geophysical Prospecting 31, 608–626).