Formation of gold-bearing veins in Otago
Schist was intimately linked to the structural evolution of the schist belt. The
currently-exploited Macraes gold deposit formed in a regional scale shear zone
during latemetamorphic uplift of the schist belt. Further exploration for this
type of deposit will be facilitated by an increased understanding of the
late-metamorphic structural evolution of the schist belt. To this end, a
three-dimensional cross section through the Otago Schist has been drawn using
structural data gathered at outcrops in a 20 - 40 km wide transect across
central Otago. This is the first continuous detailed structural section to be
drawn through the belt. The section spans an area from Textural Zone 1
metagreywacke of the Torlesse terrane in the northeast through TZ 4 schist in
the central region and across the Caples-Torlesse boundary to Textural Zone 3
schist of the Caples terrane in the southwest. Two different late-metamorphic
structural generations are identified in this section: the long-recognised
Manorburn Generation, and a new Poolburn Generation'. The location of the
Caples-Torlesse boundary has been refined on this transect by field mapping
combined with whole rock geochemistry.