Search

The Bangui magnetic anomaly (BMA) in Central Africa is one of the largest continental magnetic anomalies on Earth in terms of amplitude and lateral size. Determining the sources of the BMA can lead to an increased understanding of the crustal dynamic in the Central African sub-region and the African continent as a whole. Magnetic and gravity analysis-based derivative, two-dimensional forward modelling and a Curie isothermal depth, showed that (a) the bottoms of the magnetic sources were between 15 and 35 km; (b) the BMA is a coalescence of several anomalies that trend E-W and roughly NE-SW. These directions coincide with regional Pan African-aged shear zones along the Central African orogenic belt and to thrust sheets at the northern edge of the Congo Craton. The depth of magnetization does not exceed 35 km with the amplitude of magnetization becoming smaller in the Central African Republic. The potential magnetic susceptibility sources have an average density of 2850 kg/m3 and magnetic susceptibilities between 0.06 and 0.25 SI. The BMA is interpreted to be a combination of middle and lower crustal bodies that are not continuous and consist of magnetic mineral rich granulites and banded iron formations. The gravity and magnetic modelling indicate that the entire crust was involved in the Pan African collisional event similar to what is seen in the Mozambique belt in East Africa. Combined with geological and geochemical studies, the models add evidence that one or two subduction zones were involved in accreting terranes on the northern edge of the Congo Craton. The tectonic accretions caused a crustal remobilization along major shear zones that has locally contributed to a probable circulation of fluids enriched in ferromagnesian minerals during late Neoproterozoic magmatism that created the BMA sources. • Magnetic susceptibility sources of the Bangui Magnetic anomaly were imaged using 2D interactive models and were found to be up to 35 km in depth. • The sources of the BMA are lower and middle crustal banded iron formations and mafic-rich granulites that are part of the Central African Orogenic Belt at the northern edge of the Congo Craton. • Integrated with gravity data modelling, the sources of the BMA must be related to tectonic processes. • The depth and extent of the magnetic susceptibility sources suggest that the Central African Orogenic Belt was formed during subduction zone processes between the Saharan Metacraton and the Congo Craton during the latest stages of the Pan African orogeny. [ABSTRACT FROM AUTHOR]