Conductivity-depth transformation of fixed loop TEM data

Abstract

A computationally efficient transformation is being developed to convert fixed loop TEM profiles to apparent conductivity versus depth pseudo-sections. Such pseudo-sections facilitate first-pass interpretation for geologists and geophysicists alike. Following Fullagar (1989), the apparent depth at each delay time is equated to the depth of the current maximum in a half-space with conductivity corresponding to the apparent conductivity at that time. The non-uniqueness in the apparent conductivity at any (x, t) can be overcome by identifying the unique apparent conductivity associated with downward current diffusion. Initial applications of the transformation to theoretical TEM decays and to field data from the Canning Basin demonstrate its capability to provide a reliable qualitative portrayal of conductivity structure.