Electrical resistivity imaging and 3D geological modelling of the sedimentary architecture of the Sanaga floodplain (Cameroon, Central Africa)

The sedimentary architecture of the Middle Sanaga deposits in the Central Cameroon Region was studied by combining sedimentological and surface geoelectrical techniques. Lithologic columns from hand augers and pits were correlated to geoelectrical profiles. All of these data were analysed to determine the volumes of lithological units that constitute significant potential geomaterial deposits (gravels, sands, and clays). From surface to depth, geoelectrical results show four main units: conductive GU1 (100 Ωm), semi-resistive GU2 (800 Ωm), resistive UG3 (1000–2000 Ωm), and highly resistive GU4 (over 2000 Ωm). The calibration results identify three lithological units: LU1 composed of poorly sorted pebbles and gravels; LU2 consisting of well-classified medium to coarse sands, asymmetry towards fine to coarse elements; and LU3 consisting of silty clays and clayey sands. Correlation of results assigns UG1 and LU3 to low hydrodynamics, GU2 and LU2 to medium hydrodynamics, and GU3 with LU1 to high hydrodynamics. A 3D filling model has been developed. This model shows that the volume of GU1-LU3 is estimated of 33,549,496 m 3 , for GU2-LU2 is estimated of 18,352,728 m 3 , and of GU3-LU1 of 7,687,875m 3 . This study has important implications for the knowledge and characterization of lithological units, especially geomaterials.