Otago, New Zealand
Otago has a rich history of mineral exploration and mining dating back over a century to the first prospectors who discovered gold and began alluvial operations in the 1800’s through to the Macraes Flat open pit mining in the 90’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, 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 from this 2002 study can be seen below and large regional targets were produced for Otago.
In 2004 Kenex undertook a new modelling study over the Otago region and used new geological mapping by GNS Science (QMAP series) and an improved geochemical database to refine the modelling by GNS Science (Partington and Sale, 2004). As shown in the figure below this modelling led to a significant reduction in the prospective regions for mineralisation and allowed explorers to target areas in more detail 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 refine the prospective areas of the 2004 and 2002 studies.
Prospectivity modelling results of eastern Otago from 2002, 2004, and 2006
In 2007 Glass Earth Ltd started an aggressive 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 Otago. 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 in the last four years, which when compiled, will allow new advanced modelling studies for orogenic gold and tungsten in Otago to be undertaken.
We are eagerly awaiting the public release of this data and the release of Mesozoic lithology and structure mapping by GNS Science to undertake this new prospectivity modelling of Otago.