Contributions of Aeromagnetic and Field Surveys to Geological and Structural Mapping of Pan-African Province of South Maradi, Southern Niger

Abstract

This study focused on geological and structural mapping of Pan-African Province of South Maradi by using the aeromagnetic and filed surveys. The study zone corresponds to the northern part of the Benin-Nigerian Shield, belonging to the Pan-African mobile zone in the East of West African Craton. Previous geological work dates from the 1970s and limited to the summary geological map. According to this work, basement formations crop out discontinuously and are not subject by a structural study. In addition, the use of this map reveals a problem of correlation between the geological contours described on the existing map and those observed in the field. A combined analysis of aeromagnetic and field data led to complete then correct the petrographic and structural gap existing in the previous summary geological map since 1970s, which allowed to produce a new geological and structural map of studied zone (South Maradi Pan-African province). Petrographic and structural analysis of this new map shows that the spatial distribution of geological formations is characterized by the alternating Schist Belts and mylonitic gneiss Shear zones associated with migmatites panels and granitoïd intrusions. Thus, the different petrographic facies mapped are represented by schists-micaschist, mylonitic gneiss, migmatitic gneiss and intrusive porphyric granites. Previous data revealed a petrographic and structural continuity between South Maradi Pan-African formations with those of contiguous Pan-African province of North Nigeria.