Lyttelton, Banks Peninsula, Christchurch City, Canterbury Region, New Zealandi

Regional Level Types
Lyttelton	Volcanic Field
Banks Peninsula	Peninsula
Christchurch City	City
Canterbury Region	Region
New Zealand	Country

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Lyttelton is a short distance south of Christchurch, accessed by road through a tunnel, or if you like via a gondola. The town is wedged up against a very steep hillside, with a small main street of shops. The port at the base of the town is the South Island's main harbour. Both the port and town were greatly damaged by the 2011 earthquake, the epicentre only 2 kilometres east of the town. The area is very scenic, looking across the Lyttelton Harbour to the Banks Peninsula.

The area has attracted geologists since early times of European settlement, due to its obvious volcanic footprint, and probably ease of access from Christchurch. Theories over the evolution of the volcano have changed over time. This article is a very brief summary of (Hampton, 2010).

The Lyttelton area represents the remnants of two large composite volcanoes, the first centred on Lyttelton Harbour (11-9.7 Ma), and incorporating the north-western one third of the Banks Peninsula facing Lyttelton. The second was the Akaroa Volcano (9.8-8 Ma) centred on the Arakoa Harbour, and forming the rest of the Banks Peninsula. The Mount Herbert and Diamond Harbour Volcanics are recognised as an intermediate period of volcanic activity along the northern Banks Peninsula as activity migrated south-east.

Theories have evolved regarding the Lyttelton volcano from one main vent building a symmetrical large cone shaped volcano, the vent near Quail Island. Then two vents were proposed, one at the Head of the Bay, and a later vent at Charteris Bay. Hampton proposed five overlapping volcanic zones, and fifteen eruptive centres, as a far more complex picture.

Basement rocks in the Lyttelton Harbour area are the late Triassic sandstone, mudstone, and chert, as a large sub-marine fan complex. The Lyttelton eruptions produced hawaiite, sub-ordinate basalt, mugearite lava flows, and interbedded sediment. Successive eruptions partly overlapped previous volcanic activity, and infilled craters. At the end of each eruptive period, radial trachyte and basalt dykes formed around the vents. Some fed lava flows, or produced parasitic cones on the flank of the volcano.

Lava flows are one to ten metres thick, with limited pyroclastic layers, dipping away from the harbour by 30 degrees, as hawaiite, and basantoid lava flows, epiclastic deposits, basalt, welded tuff, domes, sills, and dykes. The five overlapping eruptive centres proposed by Hampton are Head of the Bay, Governors Bay, Whakaraupo, Mount Evans, and the Remarkable Cones. Each shows stratified lava flows, pyroclastic deposits, radial dyke formations, interbedded epiclastic deposits, and outer flank scoria cones.

After volcanic activity ceased erosion formed valleys, the major one, the Lyttelton Harbour, invaded when sea levels rose. Still later glacial sediment eroded from the Southern Alps extended the eastern shoreline of the South Island eastwards until it joined the Banks 'island' to form a peninsula as part of the mainland.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded from this region.

Mineral List

Mineral list contains entries from the region specified including sub-localities

19 valid minerals.

Rock Types Recorded

Rock list contains entries from the region specified including sub-localities