Broken Hill Zn-Pb-Ag Project
Altius Australia Pty Ltd. holds a 100% interest in 3 granted Exploration licences over an extensive area (347 km2) of largely untested prospective Broken Hill Group stratigraphy under cover in the western part of the Broken Hill district (Figure 1).
The Broken Hill deposit is the largest single sediment-hosted Zn-Pb-Ag deposit in the world and has been mined continuously since the late 1800’s, and the region continues to support three mining operations. The project area lies under cover to the west of the outcropping area of the Broken Hill block. Whilst there has been previous exploration, the large area under claim has only hosted a total of 18 drillholes which intersected basement. These drillholes have largely confirmed the presence of prospective Broken Hill Group rocks.
Reinterpretation of magnetics and gravity (Figure 2) has allowed the identification of a likely synsedimentary growth fault which marks a transition from relatively thin Broken Hill Group to a relatively thick and polydeformed sequence in the main part of the tenement. Reprocessing of gravity data has allowed the recognition of a gravity ridge which crossed this structure and may be related to underlying faults and/or lithological boundaries. The small amount of drilling in the area has confirmed the presence of Broken Hill group rocks, though the main target area has not yet been tested
Magnetic interpretation on this area has allowed the recognition of a structural inlier of Broken Hill Group within stratigraphically lower and more magnetic rocks. Within this package there are a number of strike-discontinuous magnetic anomalies which may represent the BIFs often encountered in association with Broken Hill lode rocks. The overall geological setting in this area is somewhat analogous to that seen at Cannington in Queensland, another BHT deposit.
In this area, subcrops of Broken Hill group lie under shallow cover. Previous exploration has been strongly focused on geophysics, and there is potential to trial geochemical approaches which may identify systems not tested in previous programs.
Broken Hill’s silver endowment also places it amongst some of the greatest silver districts in the world, though little attention has been paid to the high-grade silver targets in the district. The project hosts a large number of silver occurrences and historical mines which were exploited in the late 1800’s, the most important of which was the Umberumberka mine (within EL8485), which produced 43,000 tonnes at an average grade of 10% Pb and 796 g/t Ag, including high grade samples of up to 66,650 g/t Ag hosted in quartz-siderite veins of up to 4 metres width. Historical reports and recent drilling show that mineralization remains open at depth, and the retrograde shear zones which host silver mineralization are extensive in the area under claim.
Thackaringa-type deposits occur in clusters, with some of the largest clusters occurring in the Broken Hill Block North area. The deposits form an arcuate discontinuous belt of clusters extending north-easterly along the Apollyon Valley schist zone and its forks, as well as in the Silvertone area (EL8484) where the Altius ground is located, and in the Consols mine near Broken Hill. Retrograde Schist zones control the distribution of these belts.
Joe Potter, RPGeo., is the qualified person responsible for the technical data presented herein.