Implications of gravity derivative filters and residual geoid on crustal deformations in the Anambra Basin, Southeast Nigeria

Analysis and interpretation of gravity data and its derivatives can provide valuable information on edge detection, geological structures, and deformation patterns. This study delineates crustal deformation within the Anambra Basin, Southeast Nigeria, using a combined approach of gravity derivative filters and residual geoid anomalies. First- and second-order vertical and horizontal derivatives were computed from Bouguer gravity anomalies derived from a global gravitational model using the Truncated Horizontal Plate Model. Residual geoid anomalies were derived by using Airy-Heiskanen isostatic model. These results were further processed to generate tilt angle, theta, and Tilt-Theta Angles Correlation (TTAC) maps. The derivative maps revealed multiple fault systems and structural trends (N-S, NW-SE, NE-SW) associated with rift-related tectonic activity, delineating compressional and extensional domains. High-angle faults, horsts, and grabens were discovered as the key features controlling sediment distribution and potential reservoir structures. The residual geoid and swell push force maps further made manifest zones of crustal compression and extension, corresponding to areas of sedimentary loading and tectonic uplift, particularly in the Abakaliki Anticlinorium and NE flank of the basin. While this study offers valuable structural and geodynamic insights, it is limited by its reliance on satellite-derived gravity and geoid data, which may not match the spatial resolution of terrestrial seismic surveys. This limitation suggests that the interpretations, though robust, would benefit from integration with higher-resolution seismic or borehole data. The faults and deep sedimentation (depocenters) as revealed in the derived maps demonstrate that the basin has robust structural features indicating a possible existence of hydrocarbon accumulations.