Cartographie aeromagnétique et gravimétrique multi-échelle dans l’est Cameroun

Abstract

The collision between the Congo Craton and the Central Pan-African Belt produced important geological and tectonic impacts including the setting up of tectonic accidents such as faults, fractures, dykes, folds or thrusting. The present study is based on interpretation of aeromagnetic data and EGM 2008 gravity data using mathematical operators. These data have been processed by the computer program Geosoft Oasis Montaj. Maps of the total magnetic intensity and that of the Bouguer have been established here. Qualitative analysis was based on the interpretation of horizontal and vertical gradient maps, analytical signal and Tilt angle maps, upward continued maps. Residual and regional maps were derived from gravity analysis. Quantitative analysis relied on the interpretation of Euler deconvolution maps and 2 3/4 -D modeling deduced from magnetic and gravity profiles. This work enables to bring out interpretative structural maps from magnetic and gravity lineaments. These maps highlight some tectonic accidents characterized by linear structures. Their major directions trend ESE-WNW, ENE-WSW, NE-SW, NW-SE while secondary directions follow E-W and N-S. On one hand, these linear structures are related to faults, fractures, dykes and folds; on the other hand, circular anomalies are assimilated to intrusions of high magnetic materials or granite domes. Quantitative analysis evaluates the depths of causative anomalies sources. Aeromagnetic study reveals that the disturbing sources were estimated at depths greater than or equal to 14 km and located in the western and central zones of the study area; while gravity filtering situated theses deepest sources in the south of the study area, at depths greater than 17 km. The structural elements highlighted in this study seem to correlate with the previous geological and geophysical work carried out both in the study area and at the regional scale. It seems to confirm that the study area was the scene of intense tectonic movements resulting from the collision between the Congo Craton and the Central Pan African Belt.