Bismarck Project
Bismarck JV
Canterbury holds 40% of the Bismarck Project on central Manus Island in northern Papua New Guinea. Joint Venture partner Rio Tinto holds 60% and is increasing this to 80% by funding exploration under an Earn-in Agreement.
The tenement (EL2795) covers a porphyry copper and gold province that is 35km long and 7km wide, with the mineralised corridor having a north-west south-east orientation.
Manus Island is part of a dismembered volcanic arc on the Pacific Plate. The oldest exposed rocks are mid-Eocene to early Miocene volcanic rocks with calcareous interbeds and limestone lenses. Renewed volcanic activity is marked by the deposition of the Tasikim Volcanics, considered to be the extrusive equivalents of the large, early to middle Miocene multiphase quartz monzodiorite of the Yirri Intrusive Complex. All copper and gold mineralisation appears to be genetically related to the Yirri Intrusive Complex.
Preserved roof pendants within the Yirri Intrusive Complex are typically intensely brecciated and pyrite-silica-alunite altered, characteristic of high-sulphidation epithermal systems. Elsewhere hydrothermal alteration is more typical of deeper-seated porphyry copper mineralisation, and in the southeast of the mineralised corridor low-sulphidation epithermal vein and limestone replacement mineralisation occurs.
The region has undergone extensive and locally intensive early-stage exploration over the past 50 years. Two main mineralisation styles are recognised, with strong potential for a third.
- Gold bearing low sulphidation epithermal quartz veins
- Low-grade porphyry-style copper ±gold ±molybdenum mineralisation hosted in the Yirri Intrusive Complex, and
- Potential high sulphidation copper-gold systems associated with extensive areas of silica-alunite lithocap.
Recognition of extensive lithocap in the southeast of the ELs has significant implications in the ongoing exploration for porphyry mineralisation.
Lithocaps, defined as zones of advanced argillic alteration, may form above porphyry systems and may host late-stage metal-rich ore zones e.g. the Wafi gold deposit. Fertile lithocaps may also provide vectors to concealed, sizeable porphyry copper-gold deposits at depth e.g. the Golpu copper-gold deposit.
