Gravity study of the Douala sub-basin (Cameroon) using Euler 3D deconvolution, source edge detection (SED) and special function analysis

Abstract

Gravity data over an extending section of the north west portion of the Douala sedimentary sub-basin have been processed for both shallow and deep geologic contacts. Qualitative analysis, Euler 3D deconvolution, source edge detection (SED) and analysis of some special functions (horizontal gradient magnitude, analytic signal and the local wavenumber) have been carried out. One major peak and two minor peaks were highlighted on the anomaly maps as well as three major zones of anomaly which move from a very high positive anomaly zone in the center through an average positive zone to an average negative zone. Results of Euler 3D deconvolution and SED emphasized the presence of the underlying intrusive body to depths greater than 4 km in this study area and also suggested other geologic contacts above it. Solutions of special function analysis indicated that these geological contacts consist of some major faults with N–S, NE–SW, NW–SE and E–W orientations as well as some minor faults with NW–SE, E–W and NE–SW orientations having dip directions generally pointing away from the center of the study area. The faults and contacts were shown to be buried at a minimum depth of about 2 km with the majority having a structural index value in the range − 0.8 to 0.