Sams Creek, Cobb Valley, Tasman Region, New Zealandi

Regional Level Types
Sams Creek	Creek
Cobb Valley	Valley
Tasman Region	Region
New Zealand	Country

Claimed to be the largest undeveloped gold deposit in New Zealand.

Sams Creek is accessed from the turn-off to Cobb Dam, at Upper Takaka. The creek is about half-way along this road to the Cobb Dam powerhouse, as a western tributary off the Takaka River.

Gold was discovered here in 1974, then explored by CRA. The site was explored for several years by Mod Resources, with a 2012 JORC resource of 1.0 Moz Au, at the Main Zone, half-way along the trend of mineralisation. In July 2017, Mod Resources sold most of its share, retaining 15%, Oceanagold 20%, and the balance by Condamine Resources.

Gold is found in an east-west granite porphyry dyke, extending discontinuously from the CRA named Barron Flat, just east of Takaka River, to the Western Outcrop and Riordans, near the headwaters of Sams Creek to the west covering about 8 kilometres. Gold is associated with arsenopyrite-pyrite-quartz-siderite veins as a stock work. Not all of the dyke is gold bearing.

The dyke intrudes Ordivician-Silurian metapelite, shale,and quartzite of the Wangapeka Formation, with thin lamprophyre dykes near the margin contacts, all deformed through several phases of folding. The highest gold grades are found in the peralkaline dyke at the folds, with the company identifying at least three, the major one being at Main Zone.

The riebeckite granite has been hydrothermally altered with early magnetite-siderite-biotite alteration, overprinted by sulphide-quartz-siderite veins, and quartz-perthite-albite-siderite-rutile-sericite alteration.

The veins contain arsenopyrite associated with blebs of gold, however not all arsenopyrite along the mineralised trend contains gold. The veins also contain dominant pyrite, and lesser galena, sphalerite, chalcopyrite, pyrrhotite and graphite, with minor quartz and siderite. The gold contains significant silver values, up to 30.8 wt%.

Gold flakes may be found in streams in the area, although it is likely now to be under a mineral claim. Local collectors many years ago found gold flakes while panning in Grecian Creek, east of the asbestos mine.

Mindat map is the approximate position of 'Main Zone' along the mineral trend.

Geochronology

Mineralization age: Phanerozoic : 319 ± 8 Ma to 226 ± 1.1 Ma

Important note: This table is based only on rock and mineral ages recorded on mindat.org for this locality and is not necessarily a complete representation of the geochronology, but does give an indication of possible mineralization events relevant to this locality. As more age information is added this table may expand in the future. A break in the table simply indicates a lack of data entered here, not necessarily a break in the geologic sequence. Grey background entries are from different, related, localities.

Geologic Time				Rocks, Minerals and Events
Phanerozoic
	Mesozoic
		Triassic
			Late/Upper Triassic	ⓘ Riebeckite 226 ± 1.1 Ma ⓘ Arfvedsonite (youngest age) 226 ± 1.1 Ma
	Paleozoic
		Carboniferous
			Pennsylvanian	ⓘ Arfvedsonite (oldest age) 319 ± 8 Ma

Other Regions, Features and Areas containing this locality

References