The crustal and lithospheric structure of the African continent: A first approach derived from geoid, elevation and seismic data

Despite increasing efforts in global seismic surveying and advancing knowledge on Earth's crust and lithosphere, the lithospheric structure for the biggest part of the African continent is still largely unknown. Available data come from the global model CRUST 2.0, regional tomography models and certain seismic experiments, showing that crustal thickness within the continent is very heterogeneous and varies from about 20 kilometers below the extended regions of East African Rift System to 50 kilometers underneath the thickest Proterozoic belts. The observed undulations in Moho topography and the anomalous high elevation especially in the south eastern part of the continent are debated and mainly linked to differences in age, tectonic evolution, rheology, degree of chemical modification, composition and the thermal state of lithospheric as well as sublithospheric mantle domains. Herein lies our motivation to address the detailed structure of the African lithosphere revealing Moho and LAB geometry using 1D modeling of elevation, geoid and thermal data and available seismic data to constrain the model results. We present insights into the crustal and lithospheric thickness in Africa applying a four-layered model composed of crust and lithospheric mantle plus sea water and asthenosphere, assuming Airy isostasy. This approach helps to better relate surface topography with the topography of the Moho and the LAB and contributes to improve knowledge on the lithospheric structure in Africa that, as mentioned, mainly comes from the global model CRUST2.0 and regional tomography models, which unfortunately miss a proper relation between elevation, mean crustal density and crustal thickness.