Integration of satellite gravimetry, multispectral imagery and digital elevation model for investigating crustal deformation in the Niger Delta Basin

Abstract

Remotely acquired gravity data from satellite gravimetry is integrated into the study to investigate crustal deformation in the Niger Delta Basin. The Niger Delta Basin is a well-documented example of a passive margin delta that has gravitationally deformed. The gravity-driven deformation has not been fully understood, and new trends may be emerging. In this study, we assess and delineate structural deformation and sediment accumulation of the Agbada and Akata stratigraphic sequences within the basin's prograding clastic wedge. This was done through the integration of data from the Gravity Recovery and Climate Experiment (GRACE) mission, Landsat 8 satellite imagery, and the Advanced Land Observation Satellite (ALOS) World 3D-30 m (AW3D) DEM. The methodology workflow incorporated gravity modelling from GRACE data, lineament extraction from Landsat imagery, and drainage network analysis from the AW3D DEM. The Niger Delta Basin as seen on the gravity models depicts large-scale block faults with a well-defined graben structural topography. This eventually shows that the basin is dominated by growth faulting with differential subsidence. The predominant directions of the mapped lineaments are in the N-S and W-E directions. With over 18,500 lineaments, the W-E direction is marginally the dominant direction of the two predominant directions. Many linear structures such as shear zones and fractures which have different orientations and directions characterise the study area. Also present are the minor N-S fractures which are attributed to brittle deformation and sets of NE-SW and NW-SE trends, produced by transcurrent movements as the structural framework of the Nigerian basement complex are dominated by the NE-SW lineaments. However, the complexity in the structural geometry and thrusting sequences in the Niger Delta shows the patterns of growth structure and imbricate thrusting. The structural pattern also exhibits outward radial gravity spreading of dip-orientated, extensional structures that include delta slope radial grabens and tear faults. Radial spreading has likely increased the segmentation of Niger Delta regional depo-belts in the N-S direction. It is observed that most of the structural deformations in the basin are syn-formational, evolving at the same time as sediment deposition.