Topography of the Moho Undulation in Cameroon from Gravity Data: Preliminary Insights into the Origin, the Age and the Structure of the Crust and the Upper Mantle across Cameroon and Adjacent Areas

Abstract

In this paper, the complete Bouguer anomaly data from Cameroon and part of the neighboring countries has been examined to compute the topography of the Moho undulations. This work is based on an improved filtering technique and an appropriate density contrast between the crust and the upper mantle. Comparison with seismic data shows that our Moho map defines better the continuity and morphology of the crust-mantle interface than the scattered seismic data in Cameroon. The present relief map, although may not give real depths at some areas provides a better surface correlation with the surface geology better than seismic techniques. Comparison between the Moho undulations and the topography maps reveals that the crust in Cameroon seems to not be in isostatic equilibrium. The Moho in the Central African Shear Zone (CASZ) must be linked with different dextral movements during the opening of the south Atlantic in the Cretaceous time. In the Chad basin, the Moho is associated to the opening of the central and south Atlantic ~130 Ma. In the case of the Congo basin, the Moho undulations are related to the post rift subsidence. The correlation between the Moho undulations map with the surface geology indicates that the actual morphology of the crust mantle interface in Cameroon can be related to the build-up of the West and Central African rift system dating back to the Early Cretaceous to Palaeogene, where the presence of intraplate tensional stresses reactivated previous shear zones of lithospheric weakness during the break up of Gondwana.

Depth and Lineament Maps Derived from North Cameroon Gravity Data Computed by Artificial Neural Network

“…The inputs , k=1,...,K are multiplied by weights and summed up together with the constant bias term . The resulting 1 3 is the input to the activation functions g and f. The activation function is originally chosen to be a relay function, but for mathematical convenience a hyperbolic tangent (tanh) or a sigmoid function is most commonly used.…”

“…The Northern Cameroon and its surroundings, the subject of this study, have prompted many researchers and prospectors to identify superficial and deep structures and to indicate their geodynamics and tectonic implications [1][2][3][4][5]. The vast majority of these studies used the data from surveys carried out by French Research Institute for Development (IRD) and other private and public institutions.…”

Depositional and Structural Styles in the Logone Birni Basin (LBB), Northern Cameroon, from 3D Potential Field Modeling: Preliminary Results

“…By following this approach, we are sure to remove the effect of deeper sources from the gravity and therefore the upper crust signal is enhanced and useful for the purpose of our 3D model (Figure 2(d)). To calculate this gravity effect, we take advantage of the Moho map recently published by [32] (Figure 2(b)).…”