Otago, New Zealand
Otago has a rich history of mineral exploration and mining dating back over a century, from the first prospectors who discovered gold and began alluvial operations in the 1800’s through to the Macraes Flat open pit mining in the 1990’s.
The Otago region contains Mesozoic schists, which are well known in New Zealand to host gold from orogenic mineralisation. Shear zones in the schists have become structural hosts for gold, which precipitates from fluid produced during metamorphism. Today explorers are using modern geological and geophysical techniques to locate these mineralised shear zones, and Kenex are helping them interpret the wealth of geological data being collected to prioritise their exploration programmes saving them time, resources and money. Due to the mineral potential of the region and the wealth of digital geological data available, Kenex have been actively involved in prospectivity modelling studies in the region, and have assisted clients with permit management and follow-up exploration of model targets.
The first GIS prospectivity model of the Otago region was undertaken by GNS Science. This team, then led by now Kenex Director Greg Partington, modelled orogenic gold throughout the South Island of New Zealand in both the Mesozoic and Palaeozoic schist belts of New Zealand (Partington and Smillie, 2002). Initial modelling in 2002 from this study produced large regional targets, as can be seen below in the leftmost image.
In 2004 Kenex undertook a new modelling study over the Otago region, using updated geological mapping by GNS Science (QMAP series) and an improved geochemical database to refine the previous modelling by GNS Science (Partington and Sale, 2004). As shown in the central figure below this modelling led to a significant size reduction of the prospective regions for mineralisation, thus allowing explorers to target areas more precisely for new exploration permits and data collection.
Our most recent phase of modelling in Otago was undertaken in 2006 (Hill and Partington, 2007) and used improved geochemical databases and geological interpretations to further refine the prospective areas of the 2004 and 2002 studies.
In 2007 Glass Earth Ltd started an extensive exploration programme over Otago, which began with the collection of regional geophysical data to interpret geology and shear zones under the large areas of fluvial and glacial Tertiary cover units. In subsequent years Glass Earth undertook follow-up geochemical sampling and geological mapping of exploration targets.
Along with Glass Earth, several other exploration companies have collected new geological data throughout Otago. This data, when compiled, will allow new advanced modelling studies for orogenic gold and tungsten in Otago to be undertaken.