Integrated structural characterization from airborne geophysical data and field observations: A case study from the left bank of the Sankarani River (Southern Mali)

Magnetic and electromagnetic surveys carried out over the left bank of the Sankarani River, in southern Mali, outline a structural pattern that matches field observations in key areas. Residual field data with values ranging from -173.94 nT to 286.85 nT were used to produce various maps. These data (magnetic and electromagnetic) show a set of magnetic and conductive lineaments-oriented NW–SE, N–S, NE–SW, and E–W. Several coincide with mapped structures and correspond to major discontinuities, including shear zones that can be followed to depths of several hundred metres. Field-based structural analysis confirms that these lineaments correspond to a complex deformation history involving four successive phases, labelled D1 through D4. D1 reflects a continuum of deformation subdivided into two stages: D1a, associated with WNW–ESE coaxial shortening and responsible for fold stacking and thrusting; and D1b, characterized by NW–SE ductile shearing that generated predominantly sinistral N–S strike-slip faults, dextral NE–SW conjugate faults, and an NNE- to NE-trending foliation. D2 records NE–SW shortening and is associated with disharmonic folds (P2) and a second schistosity (S2). D3 corresponds to brittle deformation of late Eburnean age, while D4 is marked by the intrusion of Mesozoic dolerite dykes reflecting late-stage structural reactivation. The overlay of interpreted lineaments with artisanal gold mining sites reveals a strong spatial correspondence, particularly along shear zones. This association supports a structural control on mineralization and highlights the metallogenic significance of these features for identifying prospective areas. • Four deformation phases (D1–D4) shape the Sankarani left-bank tectonic evolution. • Geophysics reveal three main lineament families: NW–SE, NE–SW, and E–W. • D1 transpression links coaxial folding with sinistral and dextral shearing. • Gold mineralization aligns with shear zones and lineament intersections. • Integrated structural–geophysical analysis guides exploration in the Leo-Man Shield. • Structural evolution reveals prolonged tectonic activity from ductile to brittle regimes.