Geological models deduced from gravity data in the Garoua basin, Cameroon

Abstract

Bouguer gravity anomalies in the Garoua sedimentary basin are separated into regional and residual gravity anomalies. The technique used is analytical and is based on polynomial fitting. The data obtained have been interpreted along four profiles to determine the geometry of the basin, the thickness of its sediments as well as the structure of the basement below these sediments. The regional Bouguer anomaly map obtained from the third-order polynomial fitting presents a relative positive anomaly trending eastwards. The corresponding residual anomaly map shows negative anomalies of short wavelength. The models proposed from this interpretation are characterized by the accumulation of sandstone in the basin. The thickness of these sediments has been estimated to be up to 4 km. The continental crust below the basin is thinner (about 24 km) than the normal crust, but may be a little thicker to the east. This thinning is probably due to the extensional process of basin formation in the Cretaceous. The Moho is found to be uplifted in the basin, and would be the result of this extension and the associated thermal and isostatic compensation. © 2005 Nanjing Institute of Geophysical Prospecting.