Cowan Creek, Burke River, Westland District, West Coast Region, New Zealandi

Regional Level Types
Cowan Creek	Creek
Burke River	River
Westland District	District
West Coast Region	Region
New Zealand	Country

A study by Cooper (1996) was conducted on various sites in the Cowan Creek area, as part of a swarm of lamphrophyre dykes, 25 kilometres wide, and 110 kilometres long in the vicinity of the Alpine Fault.

The main interest was baotite, which is a rare Ba-Nb-Ti chlorosilicate. It is the first silicate that has quadruple metasilicate rings in its crystal structure. It is found here as widespread in Ba-Sr rich carbonitic and sideritic ferrocarbonatites, and associated fenites, showing as richer in Nb and Fe than previous studied samples of the species. The material is largely pale to dark brown grains and granules up to 0.5 mms.

The eastern wall of Cowan Creek shows a site of a 1.4 metre thick Ba enriched norsethite dominated sill, with a surrounding 10 metre wide fenite zone. The sill is zoned from aegirine-albite-niobian rutile norsethite schist adjacent to the carbonatite contact, to an intermediate zone with added magnesioriebeckite, magnesio arfvedsonite, and barian muscovite, to country rock of garnet quartzofeldspathic schist.

The western wall of Cowan Creek shows a 22 metre wide zone of carbonatite, fenite, and altered lamprophyre. It is a siderite rich carbonatite, containing rare granules of baotite up to 0.5mms, associated with niobian rutile, sphalerite, and pyrite.

On the northern slopes of Mount Campbell, 1.5 kilometres north of the headwaters of Cowan Creek, is a baotite bearing ankerite carbonatite intrusion zone, and adjacent fenite. Baotite is found associated with sulphides as 0.6 mm granules and grains along albite boundaries. In the adjacent fenite, baotite is found as intergrowths with niobian rutile, or as intergranular skeletal grains to 0.2 mms.

Other Regions, Features and Areas containing this locality

References