High definition gravity surveys and density modelling for kimberlite exploration

Abstract

Gravity data obtained at Hiles Lagoon, near Terowie, indicates the presence of a subtle gravity low. The 5 mm s-2 gravity low over the lagoon possesses roughly circular dimensions with a diameter of approximately 200 m and is the likely response of a concealed kimberlite pipe. These results are of particular interest since previous aeromagnetic and aeroradiometric geophysical surveys have had little success in detecting a kimberlite pipe at Hiles Lagoon. Density determinations typical of weathered Australian kimberlites and shales were employed to create a structural model of a kimberlite pipe and the surrounding country rock. Resulting gravity raster images from the kimberlitic model allow us to confidently interpret the field response as a kimberlite pipe and justify the application of the gravimetric technique as a tool for detailed exploration.