Structural settings of gold deposits within the Reefton goldfield, western New Zealand

The Reefton goldfield includes the large Globe Progress and Blackwater deposits as well as similar to 30 smaller deposits which are localised along a network of late syn- to post-metamorphic faults and shear zones that extend 25+ km in a northerly direction. The Globe Progress deposit is located in a unique structural site where this district-scale zone of mineralised faults and shear zones splits into two strands. Lense-shaped zones of mineralised quartz veins <100 m long which form the smaller deposits plunge parallel to intersections between their host faults and the S-2 cleavage or bedding. Veining likely developed in minor dilational jogs where the faults refract across cleavage or bedding. Some dilational jogs formed during dextral strike-slip and transpressional-reverse movement along the host faults in response to a NE-SW oriented sigma(1). Faults that host the smaller deposits are located on east-dipping fold limbs, whereas the larger, tabular rather than rod-shaped, Birthday Reef at Blackwater is the only deposit and associated fault located on a WNW-dipping fold limb. This unusual structural setting was presumably more conducive to dilational opening in the prevailing stress field. None of the deposits within the goldfield are located in major fold hinges.