Parameter estimations and basement mapping using gravity inversion with known depth constraints

ABSTRACT Mapping basement relief in sedimentary basins is of great significance for resource exploration. Inverting gravity anomalies to obtain basement depth requires prior information on the mean basement depth and the density contrast between the sedimentary layer and the basement. However, these two key parameters are often difficult to determine accurately. A gravity inversion method for basement depth using known depth control points as constraints was proposed. This method does not require prior knowledge of the mean depth and density contrast, as they are automatically updated during the iterative estimation of the basement relief. Tests on synthetic models of sedimentary basin basements confirmed the validity of our proposed method. The method is unaffected by constant offsets in the gravity anomaly and requires only two depth control points to automatically estimate the basement depth. It is also applicable to models with variable density contrasts, as it automatically obtains a density contrast that matches the gravity anomalies and known depths, representing the average effect of the density contrast across the entire sedimentary basin. The method is sensitive to noise in gravity data, so filtering of the gravity anomalies is necessary before inversion. Additionally, because the method relies on known depth control points, it is sensitive to uncertainties in the control point depths. The correctness of the proposed method is ultimately verified through its application to mapping the basement depth of the Ordos Basin.