Short Note: Early seismic refraction and gravity exploration over the Blendvale MVT lead-zinc deposit, Western Australia

Abstract

The area around the Blendvale Mississippi Valley-type (MVT) lead-zinc deposit at Pillara, Western Australia, has presented many exploration challenges over the past 30 years. This region of the Lennard Shelf was initially explored for MVT deposits using systematic grid drilling that led to the discovery of Blendvale and other deposits. However, the relatively high cost of this approach for deeper exploration prompted extensive testing and application of various geophysical methods over an extended period (Scott et al., 1994). Recently, Fullagar et al. (2004) presented a 3D gravity interpretation of the upper surface of the dolomitic limestone containing the Blendvale deposit. Accurate location of this interface is important to exploration of this ancient reef complex. This gravity interpretation exploited the large density contrast between the overlying shales and siltstones and the limestone, and was constrained by 561 boreholes that intersected the upper limestone surface. Fullagar et al. (2004) recognised that seismic methods are applicable to the problem of mapping this surface, but no seismic interpretations over this deposit were presented or discussed.