High precision structural mapping using advanced gravity processing methods: a case study from the North region of Cameroon

Abstract

The main purpose of this work is to perform a high-precision mapping of geological features (lineaments and faults) likely to develop underground aquifers in the crystalline and metamorphic rocks of northern Cameroon. The main techniques used for gravity data processing included the tilt angle of horizontal gradient (TAHG), the improved logistic filter (ILF), the fast sigmoid edge detector filter (FSF), and an edge detection filter based on the arcsine function (ASF). Before applying these edge detection filters to major geological units of North Cameroon, their effectiveness and performance have been assessed through synthetic gravity data with and without gravity perturbation. In addition, the Euler deconvolution formula has been used to estimate the position and the apparent depth of anomalous gravity sources in the study region. It appears that the main structural features are trending along the N-S, NNE-SSW and NE-SW directions. The deepest density anomalies in the region are identified in the NW-SE direction, which coincides well with the extension of the West and Central African rift system in the study area. The advanced edge detection techniques and the Euler deconvolution method have both identified a network of superficial lineaments around longitude 13oN and latitude 8oN, and located between 0 and 4 km depth. The NW-SE trending crustal features outlined in the northeast of the region, indicate that the area would have been the target of a uniform tectonic activity. This work is a contribution to a better knowledge of the configuration of fractures network, and to a better exploitation of groundwater resources available in the region.