Recent electromagnetic (EM) surveys undertaken over Silver City Minerals’ Razorback West project near Broken Hill in far west New South Wales have recognized EM conductors thought to be indicative of zinc-rich sulphide. The surveys identified subtle, but persistent patterns of anomalism which correlate well with known zones of zinc-lead-manganese and garnet-rich alteration.
Silver City’s managing director Chris Torrey says, “The new EM conductors, while subtle in character, display remarkable spatial coincidence with elevated base metal mineralization outlined in drilling. This conductive response might relate to zinc-rich sulphide accumulations at depth and as such provide exciting new drill targets for follow-up work.”
The surveys reveal a weak moving loop EM conductor extending for more than 1km along strike. A possible fixed loop EM conductor is directly coincident with the moving loop conductor and extends over 400 metres of strike.
Strong spatial correlation exists between conductors and distinctive zinc-lead-manganese mineralization and alteration minerals in shallow RAB and RC holes. Interpretation suggests that the fixed loop EM conductor lies at least 120 metres vertically below surface. Drilling in this zone to date extends only to 80 metres below surface.
The Razorback Exploration Licence lies about 15km to the northeast of the very large Broken Hill zinc-lead-silver deposit. Broken Hill has been mined continuously for more than 125 years, currently supports two mining operations and is the largest and highest grade zinc-lead-silver deposit in the world.
The ore body and its hosting corridor of alteration trend in a northeast-southwest direction. Ore zones lie within the north-western should of a very large gravity anomaly.
The Razorback West project lies in the southern part of the corridor in a broad river valley with extremely poor outcrop. Most of the area of interest is covered by a veneer of alluvium and soil to 20 metres thick. Silver City has outlined a zone of coincident geochemical, induced polarization and gravity anomalism that extends for about 5km and is up to 800 metres wide.