The gold province of Otago occupies an area of upwarped basement, the Otago Schist, comprising predominantly
quartzofeldspathic and volcanogenic metasediments. This assemblage is the product of collisional tectonic deformation
and associated metamorphism, mainly to lower greenschist facies, during the Rangitata Orogeny (200-100 Ma).
Historically this region has produced 240 tonnes of gold, 4% (10 t.) of which was from the mining of Cretaceous gold- quartz mineralised vein systems. Auriferous vein systems in the Otago Schist are mainly hosted within NW trending
normal fault-fracture arrays, however NW trending reverse fault-hosted vein systems also occur. We propose that the Late
Cretaceous-mid Tertiary Otago Schist structure represents a regional anticlinorium containing flexural folds of at least two
wavelengths. The anticlinorium structure has been quantified by determining variations in angular discordance between
schistosity and the Otago Peneplain, a Late Cretaceous-mid Tertiary erosion surface covering most of the Otago district. A
structural model for the evolution of the post-collisional anticlinorium requires the cooling surficial zone (carapace) of a
retrograding metamorphic belt to behave as an elastic lid. Erosion of topographic load on the carapace drove isostatic
uplift, which was greatest in the tectonically thickened core of the orogen. In this way differential uplift produced flexural
deformation in the elastic carapace, expressed as a large scale arching of the orogenic belt. Flexure created tangential
longitudinal strains in the outer-arc, leading to extension and the formation of mineralised normal faults. These structures
are separated by a neutral surface from shortening and associated mineralised reverse faults in the inner-arc. Our structural
model predicts that the distribution of auriferous lodes should be localised about zones of maximum flexural curvature,
where the tangential longitudinal strains are highest. As a result, NW-SE hinge regions separating schistosity dip domains
in the Otago gold province may have new found significance as potential exploration targets.