South Island, New Zealandi

Regional Level Types
South Island	Island
New Zealand	Country

The largest island of New Zealand.Metamorphosed sedimentary and volcanic rocks.

The South Island is split into regions: Canterbury, Marlborough, Nelson, Otago, Southland, Tasman, and West Coast. All except Tasman and Nelson, also contain districts.

On a geological timescale the South Island of New Zealand is young. The oldest rocks in New Zealand are Cambrian aged found in the Cobb Valley.

Most of the South Island is greywacke, or transformed to schist in the west and south. Cutting through the island is the Alpine Fault, marking the boundary of two major tectonic plates. To the east of the fault the land is generally rising, while to the west in Nelson, Fiordland, and Stewart Island the rocks are older granitic, some parts sinking forming drowned valleys.

The most widespread greywacke rock is the Greenland Group found on the west side of the South Island, with the Torlesse greywacke forming the Southern Alps. The Western Arc and Murihiku rocks formed from a volcanic chain with ash hardening over time, and is found mainly in Southland. The Haast Schist occupies large areas of Otago and Southland.

Low lying lands sank when New Zealand broke away from Gondwana, in the process coal deposits were formed, and marine animals created limestone in many areas. As New Zealand split from Australia, large volcanoes formed 12 to 13 million years ago forming the Banks Peninsula, and landscapes around Dunedin. Substantial mountain building occurred 5 million years ago as New Zealand started sliding past the Australian plate, forming the Southern Alps. These are still the fastest rising mountains in the world, at 1-2 metres per century. Subsequent erosion formed the Canterbury Plains to the east.

Nephrite (called greenstone, jade or pounamu in New Zealand) is found mainly on the West Coast in areas surrounding Hokitika, as isolated boulders in streams, and sometimes beaches. Many shops sell carved jewellery from it and less common as natural specimens, nearly always without location details. Goodletite is a unique gemstone rock also found in this area.

Local collectors seek out zeolites, agate, and beach stones. The zeolites are often micro, in difficult to reach locations, on private property, or active quarries. Some agate comes from the East Coast, arguably the best from the Mount Somers area.

Various semi-precious stones can be found on the beaches. Birdlings Flat south of Christchurch and Gemstone Beach west of Invercargill are the best known.

The beaches may also contain black magnetite rich, or red garnet rich sands. Gold, zircon, topaz and several other species can be found.

The South Island has produced eight type locality species (to 2017). Akatoreite makes attractive specimens, with the golden brown species set in pink rhodonite, and commonly seen for sale. The others are rarely available due to inaccessible locations:awaruite, taenite, huttonite, ferroaluminoceladonite, ferroceladonite, coombsite and wairauite.

Mining on the South Island is dominated by gold and coal. Neither tends to produce spectacular secondary species like copper, nickel, manganese etc.

The South Island has an interesting mining history. Many mining relics remain, often well advertised, with interpretive signage, from stamp batteries to semi-abandoned ghost towns. These range from roadside stops, to three day hikes up a mountain, all often within beautiful scenery. Central Otago and the West Coast are the best places to seek out these locations.

Some minor gold mining continues on the West Coast, and there is the industrial scale Macraes gold mine in Otago. There are several public fossicking sites for gold across the South Island. Gold was discovered in the 1860's, most production alluvial from streams and gravel terraces. Some quartz lodes were also mined, but only rarely at a substantial profit. Gold specimens are sometimes seen from the Queenstown area, but otherwise are rarely available.

The main interest with coal mines is the history. The best places to see this is the West Coast around Greymouth and Westport. Minor coal mining continues in Southland.

Geochronology

Mineralization age: Phanerozoic : 319 ± 8 Ma to 20.02 ± 3.64 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
	Cenozoic
		Neogene
			Miocene	ⓘ Ouachitite (youngest age) 20.02 ± 3.64 Ma Haast River, Westland District, West Coast Region, New Zealand ⓘ Ouachitite (oldest age) 22.51 ± 0.62 Ma Haast River, Westland District, West Coast Region, New Zealand
		Paleogene
			Oligocene	ⓘ Microsyenite 24.1 ± 1.2 Ma Haast River, Westland District, West Coast Region, New Zealand ⓘ Zircon 24.6 Ma Haast River, Westland District, West Coast Region, New Zealand ⓘ Glass (youngest age) 33.6 ± 1.8 Ma NE Otago Volcanic Field, Canterbury Region, New Zealand ⓘ Kaersutite (youngest age) 33.6 ± 1.8 Ma NE Otago Volcanic Field, Canterbury Region, New Zealand
			Eocene	ⓘ Glass (oldest age) 39.5 ± 1.8 Ma NE Otago Volcanic Field, Canterbury Region, New Zealand ⓘ Kaersutite (oldest age) 39.5 ± 1.8 Ma NE Otago Volcanic Field, Canterbury Region, New Zealand
	Mesozoic
		Triassic
			Late/Upper Triassic	ⓘ Riebeckite 226 ± 1.1 Ma Sams Creek, Cobb Valley, Tasman Region, New Zealand ⓘ Arfvedsonite (youngest age) 226 ± 1.1 Ma Sams Creek, Cobb Valley, Tasman Region, New Zealand
	Paleozoic
		Carboniferous
			Pennsylvanian	ⓘ Arfvedsonite (oldest age) 319 ± 8 Ma Sams Creek, Cobb Valley, Tasman Region, New Zealand

Fossils

This region is too big or complex to display the fossil list, try looking at smaller subregions.

Other Databases

Wikipedia:	https://en.wikipedia.org/wiki/South_Island
Wikidata ID:	Q120755
GeoNames ID:	2182504

Localities in this Region

References