The Britannia Granite pluton in the Karamea Batholith, South Island, New Zealand

Publisher Website
Google Scholar
Abstract
The Britannia Granite pluton (4 × 7 km), 25 km northeast of Westport, New Zealand, is intruded into Greenland Group metasediments, and is part of the Karamea Batholith. It is composed mainly of muscovite-biotite granites of three types distinguished in the field by grain-size differences. Petrographic and geochemical characters suggest that the granite belongs to the Karamea Suite rocks of Devonian—Carboniferous age. After consolidation, the southern part of the pluton underwent local high-temperature shearing, forming a gneissic granite with andalusite and/or sillimanite. Near the southern contact, the granites are greisenised, and cassiterite exists in greisenised apophyses. In the surrounding Greenland Group metasediments, gold-bearing quartz lodes occur suggesting a genetic relationship with the granite. Petrological characteristics and geochemical patterns of the Britannia Granite, as well as other Karamea Suite granitoids, show that they belong to postcollision granites. Their development was related to the tectonic juxtaposing of the Takaka terrane against the Buller terrane in mid-Paleozoic time.