Finite difference modelling of overburden effects for delineating conducting ore deposits by electromagnetic induction methods

One of the most important problems encountered in induction prospecting is the presence of a conducting overburden covering an ore target. The present study aims to model various complex geological realities consisting of conducting targets covered by relatively less conducting overlying formations. The finite difference numerical approach has been employed, and several apparent resistivity vs. distance plots obtained to study the peculiarities in the apparent resistivity vs. distance variation patterns, due to changes in the physical and/or geometrical properties of the target ore body, overburden, and host medium. Analysis of the numerical results emphasises the importance of mapping such conducting targets of geophysical interest, coupled either conductively or inductively with the overlying structures. The study may be relevant to: (i) searching for mineral deposits underlying the conducting weathered rocks, particularly in low latitudes; (ii) under-standing the response modifications due to the presence of undesirable overburden in the AFMAG frequency range; and (iii) identifying the frequency values giving rise to maximum resolution due to lateral conductivity contrasts in the subsurface conditions.