A 3D Gravimetric Model Of Las Salinas Basin, San Juan, Argentina

From a gravimetric study done in the Las Salinas basin, situated in the province of San Juan, Argentina, the geometry of the geologic structures that form this sedimentary trough could be determined. The average depth to the basement was found to be about 5 km, and it increases to the north of the basin. The depth values were obtained by applying spectral analysis and Euler deconvolution to the Bouguer anomaly chart. The alineations of the Euler solutions resulted highly consistent with the seismic interpretations and thereby permitted to confirm the existence of a wrench fault system mainly oriented north-south, which flank the sedimentary trough and cuts it off in the middle part. This information, plus densities obtained from logs of two hydrocarbon exploration wells drilled in the basin, permitted the elaboration of a gravity inversion model with variable density, which justifies the Bouguer residual anomaly. The results show that the basin extends over about 5750 km2. The sedimentary depths, reachs 5 km, is 1.5 km larger than those obtained with seismic. This leads to the assumption that our results show the depth of the crystalline basement, whereas the seismic ones indicate a shallower presence of a technical basement.