Modeling and structural inversion from gravimetric data of the San Jorge Gulf Basin, Argentina

Abstract

The subsurface structure of the San Jorge Gulf basin, Argentina, and its relationship with the regional geodynamic context have been analyzed in this contribution from gravimetric data integrated with the available geological information. Bouguer and residual anomaly maps were obtained from gravity and topographic data, and through upward continuation, respectively. From 2D models, five gravimetric lows and highs were defined in the western flank. The gravimetric minima, which were associated with a thickening of the sedimentary cover, generally have NNW-SSE and NW-SE orientations and mark an increase in the depth of the basement reaching up to 3000 m. On the other hand, the gravimetric highs were interpreted as basement horst-like structures. These configurations agree with the well data and its composite extensional structures are related to the basin's early origin and later evolution. The obtained 3D gravity model reveals the first-order geometry of the Southern Flank of the San Jorge Gulf basin eastern sector. In that sector, the anomaly obtained from structural inversion agrees with the observed anomaly within 0.4%. The 3D basement model was compared with data from 18 wells available in the area, showing low relative errors in basement depth for 13 of them. Based on the results, the use of the gravimetric method could constitute a fast, economic, robust, and reliable exploration method for the San Jorge Gulf basin. In addition, it shows that it constitutes a useful tool for the detection of structures of potential interest not yet identified.