Nonlinear 3-D inversion of gravity data over a sulfide ore body

Abstract

The horizontal gravity gradient and the principle of superposition of potential fields are used in the interpretation of gravity data from a sulfide ore body in terms of a 3-D structure of densities. The ore body is constituted of massive and disseminated sulfides, mainly of sphalerite, hosted in limestone. The horizontal gradient of the gravity anomaly lead to a rough estimate of the lateral extent of the ore body. The interpretation of the gravity data is posed as an inverse problem, and carried out iteratively, following a damped least-squares criteria. The inverse modeling was constrained with information on densities and thickness of the ore body, obtained from a borehole drilled over the ore body.