Geophysics and exploration of the volcanic hosted massive sulphide prospect near Wickliffe, western Victoria

Abstract

The Wickliffe Prospect (also known as Victor 2 Prospect) is located on the eastern edge of the Cambrian Mount Stavely Volcanic Complex near the town of Wickliffe in western Victoria. The Mount Stavely Volcanic Complex comprises volcanic breccia/ sandstones thought to be time-equivalent to the Mt Read Volcanics in western Tasmania.North Ltd regarded the prospect as an alteration system to a lead-poor, copper-zinc rich volcanic hosted massive sulphide system. Disseminated and stringer sulphide mineralisation and alteration has been discovered in the volcanic units of the Towanway Tuff, towards its stratigraphic top. This horizon has been sheared off in the Wickliffe Prospect area, but may still be present in unexplored areas to the south.Regional geophysical datasets, including airborne time domain electromagnetics, magnetics and radiometrics, together with detailed ground magnetic and gravity surveys, have been used to define lithological variations and structure but do not directly detect the mineralisation.Western Mining Corporation Ltd, Pennzoil of Australia Ltd, CRA Exploration Pty Ltd and North Ltd, have explored the prospect area. In 1977, Pennzoil discovered the stringer-type pyrite-chalcopyrite, which led to definition of the prospect. Best drilling intersections were 7 m @ 0.13 ppm gold, 1 m @ 0.93% copper and 24 m @ 0.29% copper.The mineralisation has coincident soil geochemistry copper, lead and zinc highs and geophysical responses. Magnetic induced polarization anomalies of -3 to -2 mV/V chargeability and 80–110% HN normalised horizontal field conductivity are coincident with the mineralisation. A gradient-array induced polarization chargeability anomaly of 15 mV/V was recorded, and a rapid reconnaissance magnetic induced polarization broad chargeable zone and relative phase shift anomaly of 0.3° to 0.4° are also coincident with the mineralisation.