Delineation of shallow structures in Madawara igneous complex, Bundelkhand Craton, India using gravity–magnetic data: Implication to tectonic evolution and mineralization

An integrated gravity–magnetic study has been carried out over Madawara Igneous Complex (MIC) in southern part of Bundelkhand Craton with an aim to decipher shallow crustal configuration and mineralized zones, thereby to improve the understanding of tectonic evolution of the region. Derived gravity and magnetic anomaly maps show good correlation with known geology and have delineated continuity of mafic–ultramafic intrusive bodies in EW direction. Radially averaged power spectrum (2D) and solutions derived from 3D Euler deconvolution have revealed average basement depths for gravity sources as ~0.3, 1.2 and 3.2 km, whereas for magnetic sources as ~0.3 and 1.2 km. From this study, these interfaces could be attributed to sedimentary origin for shallowest layer, mafic–ultramafic intrusive for intermediate layer and changes within the granite–gneissic basement for deeper solutions. Two-dimensional inverse modelling of residual gravity anomaly has delineated intrusion of highly dense mafic–ultramafic rocks from deeper part within the granite gneissic complex. Deeper basement from gravity and shallower from magnetic data indicate presence of two-stage magmatism within a subduction setting where the second magmatic emplacement probably occurred with a magma that comprises high magnetic material. High gravity and magnetic anomalies are observed over the mafic and ultramafic rock samples which are already identified (based on previous geochemical studies) as prospective zones for Cr, Ni and PGE mineralization. Thus, it can be inferred from this study that the mafic–ultramafic intrusive bodies are favourable targets for Cr–Ni–PGE mineralisation which may be obtained between a depth range of around 300 m to 3 km. Thus, the study enhances the scope for further integrated geophysical investigation over the identified prospective zones as well as provides important clues on magmatic evolution of the region.