Assessment of the Moho Depth Beneath Parts of Niger Delta Using Bouguer Gravity Data

Abstract

This study evaluates the Moho depth beneath the Niger Delta using Bouguer gravity data, employing empirical relations, spectral analysis, and 2D gravity modeling techniques. Three empirical relations were applied to calculate crustal thickness, revealing Moho depths between 25 km and 36 km. Spectral analysis provided depth ranges for the Basement, Conrad, and Moho at 2.6-6.3 km, 7-14.35 km, and 25-43 km, respectively. These findings correlate well with previous gravity and seismic refraction surveys. Two 2D gravity models along NE and SW profiles confirmed these depth estimates, showing basement depths of 5.20-8.60 km and 6.60-11.20 km, and Moho depths of 23.00-36.00 km and 30.60-36.60 km. The density model indicated average densities of 2.51 g/cm³ for sedimentary cover, 2.72 g/cm³ for the crustal layer, and 2.88 g/cm³ for the upper mantle. The study area features dense, thick sedimentary formations and stable tectonics due to its passive margin location. Findings highlight the importance of Moho depth in oil exploration, with the study area's crustal thickness being less than northern Nigeria's basement complex regions. Further oil exploration is recommended in areas with high sedimentary thickness, along with seismic surveys to corroborate gravity data results. These comprehensive assessments contribute to understanding the Niger Delta's geological and tectonic framework.

Keywords — Bouguer gravity data, Tectonic stability, Geological and geophysical information,

Niger Delta, Spectral analysis