What can seismic in hard rocks do for you?

Abstract

If potential field methods were sufficient for exploration of mineral resources at depth there would be no need for the application of seismic methods. The need to see deeper in the earth to find extensions of the existing ore shoots and to discover new reserves is of crucial importance in Australia where a constant decline of new discoveries is recorded over the last decade. The only geophysical method that can 'see'? deep and at the same time resolve fine geological features is seismic. However it should be noted that if mineral prospecting with seismic methods was straightforward it would have been established as the primary exploration method many years ago. One of the reasons for seismic still being largely considered as an alternative or experimental method for mineral exploration is the lack of understanding of the variability of seismic responses in different geological settings. In some cases we have excellent seismic results in other very poor. Are they both useful? Several case histories will be shown and discussed which may help us to devise appropriate seismic exploration strategy according to a type of mineral deposit. Seismic exploration of VMS (VHMS) deposits is relatively straightforward as seismic response of massive ore produces often clear signature, above the background trend. This is particularly the case in Canada, less so in Australia. Sediment hosted deposits are highly specific and could produce vastly different seismic signatures, while seismic response over IOCG f deposits is generally poorly understood. Recent seismic investigations over IOCG deposits show very promising results. As the number of seismic case histories grows it becomes clear that seismic can become a standard or even principal method for exploration of deep mineral deposits, providing that appropriate acquisition, processing and interpretation strategies are deployed.