Takitimu Range, Southland District, Southland Region, New Zealandi

Regional Level Types
Takitimu Range	Mountain Range
Southland District	District
Southland Region	Region
New Zealand	Country

This entry relates to a mapped area through the central section of the mountains. It is not a specific specimen site or mine.

The mountains consist of Lower Permian basaltic, andesitic and rhyodactic lava flows, primary and redeposited pyroclastic rocks, and epiclastic sediments. This is cut by the White Hill and MacKinnon Peak intrusives.

Houghton(1977) provides that the Takitimu Group is divided into two metamorphic zones. The upper is zeolite rich, with some crystals in cavities. Epistilbite is widespread in the area, but rare elsewhere in New Zealand. It occurs with laumontite in vesicles in lavas, and as cement in pyroclastic rocks. By foot from the end of the Aparima Track is suggested, in stream cuttings. The northern sections of the mountains is the only occurrence of yugawaralite in New Zealand, occurring in thin vesicles in dolerite. Exposed in bluffs above the bush line near the head waters of Princhester Creek.

The lower Zone 2, does not contain any zeolites. However, prehnite infills vesicles, and forms small veins, rarely areas consisting of 50-70% prehnite, possibly containing radiating masses of clear elongated pinacoidal prisms.

In general the upper Zone 1 contains analcime, laumontite, epistilbite, prehnite, albite, chlorite, calcite, heulandite, montmorillonite, celadonite, minor pumpyellite and epidote, and rare yugawaralite. Plagioclase, augute, magnetite, hornblende, and hypersthene is also noted as relict phases.

Specifically analcime is common, and associated with laumontite, epistilbite, natrolite or thomsonite, but not with quartz, as veins of limited extent, and occasionally in vesicles. Epistilbite is common in vesicles, and confined to them only in Zone 1. Heulandite is restricted to a tuff in the middle section of the mountains, largely being reconstituted heulandite-quartz. The heulandite replaces glass shards, retaining the shard outline. It also may occur in vesicles in lava flows. Laumontite is abundant in vesicles often with chlorite rims, in veins, and as cement. May occur as clear stout prisms, sometimes with a hematite dusting given the hand specimens a pink tint. Natrolite and thomsonite is rare at the location, associated with analcime in vesicles in basaltic lava flows. Natrolite as radiating sheaves of prisms set in analcime, while thomsonite is felted masses of radially orientated needles. Stilbite is only found in the MacKinnon Peak intrusives in vesicles associated with laumontite, heulandite or calcite, and in veins, sometimes with minor chabazite. Yugawaralite is associated with heulandite in vesicles, within shallow doleritic intrusives in the northern section of the mountains.

Zone 2 is pumpellyite-prehnite rich, with stilpnomelane in the northern section, and fresh plagioclase in the centre of the thick White Hill intrusives. Shear zones contain epidote-chlorite-quartz, while away from the shears, prehnite dominates.

Specifically actinolite is common in the lower areas of Zone 2 as fibrous aggregates, or chlorite-actinolite intergrowths replacing hornblende, or in the MacKinnon Peak intrusives on the margins of hornblende phenocrysts. Primary plagioclase reconstituted as albite with hematite dusting. Andradite widespread but minor as fine colourless granules in igneous rocks associated with chlorite. This latter species is the groundmass in the White Hill intrusives. Prehnite infills vesicles, as small veins, or cement in tuff breccia, or mottling in arenites, and occasionally consisting of the majority of rock at 50-70% volume.

Other Regions, Features and Areas containing this locality

References