Analysis of poorly stratified lateritic terrains overlying a granitic bedrock in West Africa, using 2-D electrical resistivity tomography

摘要: Abstract Two-dimensional electrical resistivity tomography has been employed to investigate the subsurface structure of a thick lateritic weathering mantle overlying granitic bedrock in southeastern Senegal. The resistivities were measured along two kilometric profiles insuring continuous coverage. Exploration pits exposed different layers, i.e., saprolite, mottled zone, soft ferricrete and ferricrete, whose respective thicknesses used constrain apparent resistivity, despite their spatial variations. Colour-modulated pseudo-sections versus pseudo-depth including groundsurface topography clearly show variations properties layers since changes faster than thickness. data from cross-borehole survey with estimates for aquifers granite integrated into provide more useful results about real ranges layers. resulting geo-electrical images document geometric relations between layer boundaries, particular those topographies. relationships topographies suggest that large part actual is allochthonous. This also implies surface was mainly shaped by processes while hillslope geomorphic patterns result erosion or reworked materials leading development according landforms observed. It suggested climatic implied landscape evolution our study area.