oa Three Springs Talc Mine: A new view on an old deposit

A successful application of the high resolution seismic reflection method for talc exploration, is demonstrated using an experimental seismic line, recorded over the Three Springs talc deposit. Since 1973, a variety of ground and airborne geophysical techniques had been applied to talc exploration at Three Springs, with limited success. However, wireline logging and laboratory petrophysical measurements have provided new insights into the physical properties of talc and contrasts between talc and adjacent dolomite and dolerite rocks. In particular, P-wave velocity measurements demonstrated that the elastic contrast between the talc mineralisation and surrounding rocks may be sufficient for the application of seismic reflection methods to talc exploration. Between 1989 and 1993, seismic reflection and refraction surveys were acquired on a single profile across the Three Springs talc deposit. The results of this work were disappointing, apparently contradicting physical property measurements. Greatly improved results from re-processing of the ‘old’ seismic data, in 2000, suggested seismic reflection may indeed assist in mapping of the talc mineralisation, as well as providing important detailed structural information. Additional experimental data acquisition, undertaken in 2000, confirmed the potential application of the seismic reflection method to deposit - scale talc exploration. However, whether the seismic technique can be routinely applied, in a cost - effective manner, providing the required geological detail, remains to be seen.