Contribution of Geophysical and Borehole Data in the Study of the Geological Structures of the Gantour Plateau and Bahira Basin (Morocco)

Abstract

Geophysical methods and geological investigations are efficient techniques for studying the geological structures of the sedimentary basins (Jaffal et al. Journal of African Earth Sciences 193, 2022). By integrating subsurface and surface geological information, we can improve geological modeling and resource exploration. To gather this information, we use an indirect approach that relies on geophysical methods and direct observation through boreholes and surface geological investigations. These investigations help acquire a variety of geoscientific data that can be used in resources exploration. This study focuses on the Bahira basin that hosts, with the Gantour plateau, an important part of Morocco’s phosphate reserves. The main objective is to provide a better understanding of the deep structure of the study area. The methodological approach adopted in this study concerned (i) the combined analysis and reinterpretation of existing geophysical and borehole data and (ii) the implementation of new electrical resistivity tomography surveys. The processing and interpretation of gravity data highlight the major geological structures such as faults and geological contacts that are totally or partially covered by plio-quaternary deposits. Additionally, the gravity anomalies perfectly delineated the structural highs in the basement and sedimentary thickening in depressions and grabens. Furthermore, the combined analysis of geoelectrical and borehole data provides more precisions about the deep geological structure of the phosphatic series of the Bahira basin, in terms of depth and lateral changes in thickness.