Subsurface Structural Mapping Using Combined Terrestrial and Grace Gravity Data of the Adamawa Plateau (North-Cameroon)

Bouba Apollinaire,Oyoa Valentin,Kande Houetchak Ludovic,Kamguia Joseph,Yap Loudi,Nouayou Robert,Tabod Charles Tabod

doi:10.4236/ijg.2017.87050

Abstract

In order to analyze and determine the geological structures of the Adamawa plateau, the terrestrial gravity data were combined to data computed from GGM02C gravity model. The dense gravity net obtained were further introduced into qualitative and quantitative interpretations. The resulting Bouguer anomaly map obtained from combined data shows NE-SW direction which nearly coincides with the main direction of the fractures affecting the basement in the region and indicates strong gradients marking the presence of discontinuities between heavy and negative gravity anomaly. In order to conduct the quantitative interpretation of the combined gravity data, three profiles were drawn on the residual Bouguer anomaly map and therefore were interpreted using spectral analysis method and 3D density inversion. The knowledge of the depth and density of the geological structures show an uplift of dense rocks under the granite-gneiss substratum. This dense material found in the ENE-WSW direction of the Adamawa Plateau is interpreted as basaltic intrusion probably resulting from tectonic processes. According to this study, the depths of 3.83 km and 9.62 km are the new values of depths obtained for futures investigations in the Adamawa plateau.

Highlights

The resulting Bouguer anomaly map obtained from combined data shows NE-SW direction which nearly coincides with the main direction of the fractures affecting the basement in the region and indicates strong gradients marking the presence of discontinuities between heavy and negative gravity anomaly
In order to conduct the quantitative interpretation of the combined gravity data, three profiles were drawn on the residual Bouguer anomaly map and were interpreted using spectral analysis method and 3D density inversion
The depths of 3.83 km and 9.62 km are the new values of depths obtained for futures investigations in the Adamawa plateau

Summary

Introduction

Some of the above mentioned studies are based on the geophysical signatures of geological units deduced from gravity analyses and their quantitative interpretation. A closer look to the terrestrial gravity net of the study area shows that there are many gaps. This might lead to many approximations in geophysical gravity anomaly analyses and interpretations in the region. The analyses and interpretations should be based on maps showing the real signatures of the geological features. To achieve this goal, a dense gravity net is needed. GGM02C gravity data combined to terrestrial ones will be exploited to reinforce the precision of the previous works

Methods

Results

Conclusion