The Riwaka Complex is a tholeiitic igneous intrusion (40km long, up to several km wide) located in the northwestern part of the South Island of New Zealand. It intrudes the Takaka Terrane which represents an assemblage of sedimentary rocks that are part of New Zealand's geologic Western Province (per Saunders).

The Riwaka Complex is located in the Takaka Terrane of New Zealand’s Western Province, where it intrudes Ordovician–Silurian metasedimentary rocks (Mount Arthur and Ellis group marbles, quartzites, argillites, calcareous sandstones and siltstones, carbonaceous shales and schists); and Early Devonian sedimentary rocks. The Riwaka Complex is an south–southwest to north–northeast striking, elongate composite intrusive body c. 50 km long and ≤ 6 km wide with an estimated areal extent of 130 km2. The Riwaka Complex can be divided into two main parts; a northern zone, where the younger cross-cutting, more felsic rocks occur, and a southern zone dominated by ultramafic rocks with associated local sulphide mineralisation. The Riwaka Complex is characterised by four main lithological units: Graham Peridotite, Pokororo Pyroxenite, Campbell Gabbro and Brooklyn Diorite.
Discovery of Ni–Cu mineralisation in the Riwaka Complex occurred in Prospect Creek in the Graham Valley area. Subsequently, exploration mapping, geochemical and geophysical surveys, and drilling have been undertaken in the wider Graham Valley. Exploration has shown that the mineralisation occurs as pyrrhotite–chalcopyrite–pentlandite–pyrite mainly disseminated in a 12 km long section of gabbro and pyroxenite between Graham Valley and Prices Creek. Mineralisation occurs along the margins of the complex, and is traceable by sporadic gossan outcrops and corresponding Cu–Ni soil and stream sediment geochemical anomalies.

Other Regions, Features and Areas containing this locality

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