From 2D to 3D: Prospectivity modelling in the Taupo Volcanic Zone,New Zealand |
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| Institution: | 1. EGRI, School of Geosciences, University of the Witwatersrand, PVT Bag 3, Wits 2050, South Africa;2. Geological Institute, BAS, 24 Acad. G. Bonchev str, 1113 Sofia, Bulgaria;3. Geological Survey of Norway (NGU), Postboks 6315 Sluppen, 7491 Trondheim, Norway;4. Rio Tinto Mining and Exploration, 1 Harries Rod, Illovo 2196, South Africa;1. National Authority for Remote Sensing and Space Sciences, 23 Joseph Tito Street, El-Nozha El-Gedida, P.O. Box: 1564 Alf Maskan, Cairo, Egypt;2. The Custodian of the Two Holy Mosques Institute for Hajj and Umrah Research, Umm Al-Qura University, P.O. Box: 6287, 21955 Aziziah, Makkah, Saudi Arabia;1. MLR Laboratory of Metallogeny and Mineral Resource Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;2. Centre for Exploration Targeting, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia;3. School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China;4. Beijing Institute of Geological Survey, Beijing 100195, China |
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| Abstract: | A 2D prospectivity model of epithermal gold mineralisation has been completed over the Taupo Volcanic Zone (TVZ), using the weights of evidence modelling technique. This study was used to restrict a 3D geological interpretation and prospectivity model for the Ohakuri region. The TVZ is commonly thought of as a present-day analogue of the environment in which many epithermal ore deposits, such as in the Hauraki Goldfield, Coromandel Volcanic Zone, are formed. The models utilise compiled digital data including historical exploration data, geological data from the Institute of Geological and Nuclear Sciences Ltd. Quarter Million Mapping Programme, recent Glass Earth geophysics data and historic exploration geochemical data, including rock-chip and stream sediment information. Spatial correlations between known deposits and predictive maps are determined from the available data, which represent each component of the currently accepted mineral system model for epithermal gold. The 2D prospectivity model confirms that the TVZ has potential for gold mineralisation. However, one of the weaknesses of this weights of evidence model is that the studies are carried out in 2D, with an approximation of 3D provided by geophysical and drilling data projected to a 2D plane. Consequently, a 3D prospectivity model was completed over the Ohakuri area, constrained by the results of the 2D model and predictive maps. The 3D model improved the results allowing more effective exploration targeting. However, the study also highlighted the main issues that need to be resolved before 3D prospectivity modelling becomes standard practise in the mineral exploration industry. The study also helped develop a work flow that incorporates preliminary 2D spatial data analysis from the weights of evidence technique to more effectively restrict and develop 3D predictive map interpretation and development. |
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