Mineragraphy and origin of copper-bearing sulphides at Waitahuna River, eastern Otago

Abstract

The mineralogy and textures of specimens from a sulphide occurrence in a green schist at Waitahuna River are described, and their origin is discussed. The ore minerals are chalcopyrite, pyrite, marcasite, pyrrootite, and minor sphalerite, and there is a small amount of supergene alteration. Marcasite, and the later of two main types of pyrite, are believed to have formed from pyrrhotite after the main stage of metamorphism, but are not supergene.The occurrence is thought to be a stratiform volcanic-sedimentary deposit, but the textures are mainly of metamorphic origin. Mineralogy, geological environment, and probably origin, are similar to those of the occurrence at Moke Creek, near Queenstown.

Sphalerite geobarometry in metamorphic terranes: an appraisal with implications for metamorphic pressure in the Otago Schist

“…The deposit lies in the lower greenschist facies about 30 km south-west (downgrade) of the first appearance of biotite (Brown, 1967). It is similar to the Moke Creek deposit (Henley, 1975;Lowery, 1979), but does not show the same degree of complex fabric development and corresponding overprinting metamorphic assemblages. This and the regional metamorphic pattern suggest that the peak metamorphic grade was lower at Waitahuna than at Moke Creek.…”

“…A metamorphosed Cu-Fe-Zn sulphide deposit at Waitahuna, East Otago, New Zealand, has been described in detail by Lowery (1979). Enclosing rocks are psammitic, pelitic, and greenish (metavolcanic?)…”

“…Enclosing rocks are psammitic, pelitic, and greenish (metavolcanic?) schists (Textural Zone 3; Bishop, 1972;Lowery, 1979) of the Otago Schist belt. The deposit lies in the lower greenschist facies about 30 km south-west (downgrade) of the first appearance of biotite (Brown, 1967).…”

Lithology, geochemistry, and structure of Moke Creek sulphide deposit host rocks, Otago Schist, New Zealand

“…Previous workers have drawn similarities between the Moke Creek sulphide deposit and Besshi-type deposits of the Sambagawa schists of southeast Japan (Henley 1975;Lowery 1979;Roser 1983), in which sulphide concentrations are hosted in greywacke/argillite suites associated with mafic tholeiitic volcanics (e.g., Crowe et al 1992;Zierenberg et al 1993;Prokin et al 1998). The depositional mechanism involves hydrothermal convection of sea water following the intrusion of magma into, or beneath, sediment in a rifting environment, and subsequent exhalative-type sulphide deposition on the sea water/sediment interface (e.g., Zierenberg et al 1993).…”

“…Numerous earlier workers (Wright 1966;Wood 1967;Henley 1975;Lowery 1979;Jamieson & Craw 1987) have described various aspects of the Moke Creek sulphide deposit itself, focusing on sulphide mineralogy. However, apart from generalised regional studies (Park 1909;Hutton 1940;Mortimer 1993), there is no published information on the host rocks of the Moke Creek sulphide deposit.…”