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Sterk, R., de Jong, K., Partington, G., Kerkvliet, S., van de Ven, M. "Domaining in Mineral Resource Estimation: A Stock-Take of 2019 Com-mon Practice". Mining Geology 2019 conference, Perth 25-26 November 2019
Resource blocks estimated within a particular domain should only be informed by sample points from within that domain. If this fundamental principle of mineral resource estimation is not adhered to it may severely compromise the quality of the final resource estimate. Nonetheless, the repeated reminder of resource downgrades or even complete project devaluations as the consequence of poor domaining practice suggests that this principle is still not well-entrenched in industry practice. As many practitioners have warned and as documented in books, course materials and online blogs over the years: geology is important. It is good practice to base domains primarily on geological information derived from geological logging of drill core or chips, underpinned by an understanding of the structural geometry of the ore body and a well-understood genetic model of mineralisation. However, a sound statistical analysis of geochemical data that are accurate and precise is also required to evaluate the domains. Multi-element geochemistry from laboratory or portable XRF instruments combined with multivariate data analysis and machine-learning (ML), as well as core scanners and down-hole optical televiewers, and other recent technological advances are powerful tools that enable the proper delineation of domains. However, these tools are often underutilised as they require additional investment at a time in a project when their value can be hard to demonstrate. Unfortunately, the use of geological information to create domains is the exception rather than the rule. Our review of mineral resource estimates published since 2017 suggests that more than half of all estimation-constraining wireframes are built using grade cut-offs and are not informed by any primary geological information such as lithology or alteration. While using a grade cut-off may seem perfectly logical to delineate domains when detailed geological information is not available, if not treated with caution, this can lead to poor domain integrity. Books and courses on resource estimation clearly express the importance of domaining but offer few practical solutions or rules of thumb. There appears to be a lack of clear standards, a lack of a framework to distinguish good from bad domaining practice and there is a perpetuation of bad practice masked as common practice. Here we offer some recommendations to raise domaining standards across the industry and present a rules-based approach to improve domaining practices at the individual level.
Ford, A. "Practical Implementation of Random Forest-Based Mineral Potential Mapping for Porphyry Cu–Au Mineralization in the Eastern Lachlan Orogen, NSW, Australia". Natural Resources Research, pp 1-17, November 2019
With the increasing use of machine learning for big data analytics, several methods have been implemented for the purpose of exploration targeting using mineral potential mapping in a GIS environment. Random forests (RF) have been successfully applied to data-driven mineral potential mapping using relatively small numbers of input maps that have typically been pre-classified by a geologist familiar with the mineral system being targeted. However, it is useful to understand how well RF perform for mineral potential mapping when a large number of multi-class categorical or non-thresholded numeric input maps are used in the classification or when weighted or ranked training data are used. Four different implementations of RF are presented to examine how the results vary depending on the degree of intervention from an expert in the modeling process. A case study has been devised using data from the eastern Lachlan Orogen in New South Wales (Australia) for the purposes of targeting porphyry Cu–Au mineralization related to the Macquarie Arc. The results demonstrate that the use of a large number of multi-class categorical or non-thresholded numeric predictive input maps results in a poor mineral potential map outcome. An expert review to determine reclassifications or thresholds that produce geologically meaningful maps as proxies for the mineral system being targeted results in more effective RF-based mineral potential maps being produced. Weighting or ranking the deposits used as training data produces more narrowly defined prospective areas that may assist with targeting tier-one economic deposits. Comparison of the RF results to a standard weights of evidence analysis highlighted some significant differences in which predictive maps should be considered important for modeling, and in the extent of prospective area delineated from each output mineral potential map.
Ford, A., Peters, K.J., Downes, P.M., Blevin, P.L., Greenfield, J.E., and Simpson, B. 2019. "Mineral potential mapping as a strategic planning tool in the eastern Lachlan Orogen, NSW". In: Mines & Wines Abstracts, 25-27 September 2019, Wagga Wagga, Australia (invited presentation).
The Geological Survey of New South Wales (GSNSW) is undertaking a statewide mineral potential mapping project driven by the need to provide justifiable land use planning advice to key government stakeholders and to highlight the exploration potential of the state’s major mineral systems at a regional scale. Following delivery of mineral potential data packages for the Southern New England Orogen (Blevin et al. 2017) in 2017, and the Curnamona Province and Delamerian Thomson Orogen (Ford et al. 2018) in 2018, the eastern Lachlan Orogen was selected as the next area for a review of key mineral systems and mineral potential.
Ford, A., Peters, K.J., Partington, G.A., Blevin, P.L., Downes, P.M., Fitzherbert, J.A., Greenfield, J.E. 2019. "Translating expressions of intrusion-related mineral systems into mappable spatial proxies for mineral potential mapping: case studies from the Southern New England Orogen, Australia". Ore Geology Review, Volume 111, August 2019.
An understanding of the modelled mineral system and high-quality data that accurately map this system are prerequisites for producing geologically meaningful mineral potential maps. Critical to this is the translation of the targeted mineral system components into mappable targeting criteria and their spatial proxies. This paper presents a workflow that illustrates this translation process, also highlighting that, if done well, mineral potential mapping can produce statistically valid, geologically meaningful, and practically useful results that not only predict the location of known mineralisation but also identify new target areas. An important ingredient of the workflow described herein is what we call a mineral systems atlas. This compendium includes (1) a spatial data table detailing the translation of the modelled mineral system, (2) the predictive maps that capture the mappable components of the targeted mineral system, and (3) the final mineral potential maps. A case study implementing and illustrating this workflow is presented for intrusion-related Au and Sn +/- W mineral systems in the Southern New England Orogen, New South Wales, Australia. Importantly, the mineral potential maps generated as part of this study succeeded in identifying areas of known intrusion-related Au and Sn +/- W mineralisation and new areas with high potential for discovery.
Luketina, G. 2019. "Mineral potential mapping of porphyry targets at the Bundarra Cu-Au project, Queensland". PACRIMM conference, Auckland, 3-5 April 2019
The Bundarra porphyry Cu-Au project is held by Duke Exploration Ltd., and is located in central Queensland, Australia, 110 km south-west of Mackay. The project was acquired in 2017. Kenex has completed, for Duke, detailed prospectivity modelling over the project area, and 3D modelling over the highest priority targets, in order to focus drilling funds on the most prospective areas. The project area surrounds the Cretaceous Bundarra Granodiorite, which intrudes the Permian Back Creek Group carbonaceous shales, sandstones and marls. Numerous Cu-Au occurrences are present within or near the hornfelsed contact aureole of the granodiorite. The project has been subject to significant exploration work, including mining of high grade ore shoots in the late 1800s to early 1900s, however, modern exploration has been sporadic, and without comprehensive follow-up of encouraging results.
All available historic data has been compiled and incorporated into a mineral potential map based on the porphyry mineral system. Maps representing all components of the mineral system including source, transport, deposition and trap are compared to known mineral occurrences, and the maps with the best spatial correlations have been combined to produce the mineral potential map. The results show that the Bundarra project has areas which are highly prospective for porphyry deposits. The areas of highest prospectivity have been highlighted, allowing work to focus on the targets with the greatest chance of success.
Following this work, 3D models of the two highest potential targets have been produced, incorporating field observations, historical drilling, magnetic data, and new 3D plate modelling of EM data. The 3D models will be used to inform drill targeting.
Nielsen, S.H.H., Partington, G.A. Franey, D., Dwight, T., 2019 "3D mineral potential modelling of gold distribution at the Tampia gold deposit". in:Volume 109, June 2019, Pages 276-289
A 3D mineral potential model was developed for the Tampia Gold Project in Western Australia to help constrain resource estimation, understand the distribution of gold grades from the resource estimation techniques with respect to geological and physiochemical continuity, and predict the location of new gold mineralisation for future exploration drilling to expand the gold resource at Tampia. The 3D mineral potential model was generated using predictive maps based on a local granulite-facies orogenic gold mineral system model. These were generated from regional scale data and data collected during a 40 m by 40 m resource drilling programme, and included lithology, structure, rock property data and geochemical data. The predictive capacity of each map was tested for the spatial correlation with training data from high grade gold drill intersections, using the weights of evidence technique. There were 44 predictive maps created that can be used as proxies to map the physical and chemical processes active in the orogenic mineral system at Tampia. Of these, 11 were chosen for the final model that had the highest spatial correlation with the training data and did not duplicate map patterns. A closely spaced infill drilling programme was subsequently undertaken over an area where the post probability results indicated high and continuous probability for gold mineralisation, while the resource model estimated less continuous and lower grade gold mineralisation. This infill drilling aimed to compare the gold continuity at a 10 m by 10 m drill spacing with the resource estimate gold grades and post probability distribution developed from 40 m by 40 m spaced resource drilling. The results from the 10 m by 10 m spaced drilling were thereby used to test the performance of both the resource and prospectivity models, and assess the utility of mineral potential modelling for use in developing geological domains to constrain resource estimation. Results from the first phase of infill drilling, which only covers 4% of the total model area, confirm the continuity of the post probability values and suggests that the mineral potential model predicts the location and distribution of gold mineralisation within the area drilled. The results were also better and more continuous than predicted by the resource estimate. Importantly, these results confirm that geological and physiochemical controls on gold mineralisation can be numerically measured and mapped at the scale of an orebody. This allows mineral potential modelling to be considered as an option to constrain and help inform the results of geostatistical techniques used in resource estimation.
Nielsen, S.H.H., 2019 "Targeting Lithium Mineralisation in the Taupo Volcanic Zone, New Zealand" PACRIMM conference, Auckland, 3-5 April 2019Extended Abstract
Ford, A., Peters, K.J., Partington, G.A., Blevin, P.L., and Downes, P.M., 2018, "The Southern New England Orogen Mineral Potential Project". In: Resources for Future Generations (RFG) Abstracts, 16-21 June 2018, Vancouver, Canada. [Keynote presentation]
The SouthernThe Southern New England Orogen (SNEO) in the north-eastern part of New South Wales (NSW) in Australia is prospective for intrusion-related tin-tungsten, intrusion-related gold-bismuth-molybdenum-silver, and orogenic gold-antimony mineral systems. An initiative by the Geological Survey of NSW to conduct mineral potential modelling for these mineralisation styles in the SNEO has resulted in a comprehensive account of the mineral resource potential of the region.
The Geological Survey of NSW has a successful strategy of providing high quality pre-competitive data that has been complemented and enhanced by the mineral potential mapping approach. Datasets including seamless basement geology, detailed attribution of faults, and igneous fertility that were created by the survey prior to modelling enabled an extensive number of variables be tested using spatial statistics for relevance to each mineral system. The feedback from the data processing and spatial analysis allowed improvements to be made to the data and provided information on the relevance of the datasets to mineral exploration in the region.
The outputs of the empirical models are mineral potential maps that map the geological potential of the SNEO for each mineralisation style. The models are being used for land planning and advice purposes, technical resources for improved mineral system studies (including global endowment estimations), and for promoting exploration in the SNEO through the generation of prospective targets. Due to the richness of the geoscience datasets in NSW, the technique - including the creation of high-quality datasets combined with mineral potential modelling - is now being applied to other regions and mineral systems within NSW, and is readily applicable to any other area or mineral system of interest.
Ford, A., Fitzherbert, J., Downes, P., Partington, G., Blevin, P., Greenfield, J., Peters, K. 2018. "Mineral potential mapping for pre-competitive data delivery in NSW Zone 54". In: Australian Geoscience Council Convention (AGCC) Abstracts, 14-18 October 2018, Adelaide Australia.
A collaborative project between the Geological Survey of New South Wales (GSNSW) and Kenex Pty Ltd was undertaken to evaluate the mineral potential of MGA Zone 54 in NSW as a continuation of GSNSW’s ongoing program of mineral potential mapping across the state, which commenced in the southern New England Orogen in 2017. The results of the Zone 54 project will deliver a pre-competitive geoscience data package that will be used to guide mineral exploration and land-use planning in the region. Prior to modelling, the available datasets were reviewed and updated by GSNSW to ensure accuracy and that relevant attribute information was present. Using a mineral systems approach, models were developed for Broken Hill Type Pb-Zn-Ag and IOCG mineralisation in the Curnamona Province, and Orogenic Au and VHMS mineralisation in the Delamerian-Thomson Orogens. The component processes in the mineral system models were translated into mappable targeting criteria. The key predictive variables, mapped using geological, geochemical, and geophysical datasets, were determined using spatial statistics. Mineral potential maps were generated for each mineral system using a weights of evidence approach. Area-frequency analyses show model efficiencies between 88-99%, which indicate almost all training points used to represent evidence of the mineral system being targeted are predicted within a small area. A comprehensive spatial data table outlining the details of the mappable targeting criteria and the results of the spatial data analysis, and maps of the key predictive variables were delivered, along with the mineral potential maps as a pre-competitive dataset for public release.
Puccioni, E. 2018. "Assessing polymetallic nodule deposit in the Cook Island Exclusive Economic Zone".Pacific GIS and Remote Sensing conference, 25-30 November 2018, Suva, Fiji.
With the use of GIS and geostatistical modelling techniques, we helped the Cook Island Seabed Authority to assess the potential for economic deposits of polymetallic nodule in their exclusive economic zone.
Puccioni, E. 2018. "Geo-enabling Maori iwi to make better land management decisions".Pacific GIS and Remote Sensing conference, 25-30 November 2018, Suva, Fiji.
We are currently working with several Maori iwi in New Zealand to improve their GIS capabilities and integrate spatial knowledge in their decision-making processes. The main aim of this work is enabling the iwi to create and manage their own GIS projects and use the results to enhance their day to day operations and long-term planning. In this pilot study on land use improvement with GIS and RS we created a spatial model to find the best land uses for a given land block and then integrated the results with profit forecasts in order to provide the landowners with a better understanding of the land capability. We used high resolution data captured with drones as well as freely available spatial datasets that we processed, reclassified, weighted and combined using ESRI ArcGIS software. The result is a series of land unit polygons, each representing a unique combination of possible land uses and relative forecast profit. This combined spatial and economic information provides a comprehensive understanding of the potential of a block of land. The modelling process is simple, flexible, clear to understand and easy to replicate, but more importantly it can be effectively used to make informed land management decisions
Partington, G. A., 2017 "Greenbushes tin, tantalum and lithium deposit". In: Australian Ore Deposits (ed. N. Phillips). Australian Institute of Mining and Metallurgy, Monograph Series, No. 32, pp 153-157.
The Greenbushes pegmatite contains one of the largest deposits of tin, tantalum and lithium in the world and has been in operation for more than 128 years. The deposit is located 350 km south of Perth, Western Australia (WA), at -33.86 deg, 116.06 deg in the Archean Western Gneiss Terrane. The Greenbushes deposit is receiving renewed interest due to increasing demand for lithium for battery production. Recently, Tianqi Lithium Australia formally approved the development of a A$400 million lithium plant in Kwinana near port facilities, south of Perth. In conjunction with plant approval it is planned to expand Greenbushes' lithium production, already the largest hard rock lithium mine in the world, to supply more than 30% of the world's lithium. This will increase the importance of Greenbushes as a global source of lithium in particular, with potential future production of tin and tantalum.
Partington, G.A., Davis, T.P., and Pilcher, T.W.B., 2017. "Bullabulling goldfield". In: Australian Ore Deposits (ed. N. Phillips). Australian Institute of Mining and Metallurgy, Monograph Series, No. 32, pp 211-215.
The Bullabulling goldfield straddles the Great Eastern Highway, 25 km west of Coolgardie and 70 km south-west of Kalgoorlie in Western Australia at -31.02 deg, 120.90 deg. Gold was first discovered and mined in the late 1980s at Gibraltar, which is late in the history of gold discoveries in the Yilgarn. The Bullabulling goldfield is atypical in the eastern Yilgarn because gold at Bullabulling is not associated with greenschist facies metamorphic rocks or brittle-ductile higher-grade narrow quartz vein arrays or shear zones; instead it has similarities with high-tonnage low-grade gold deposits more commonly found in the US or Canada. Recent structural analysis and 3D geological mapping of the Bullabulling gold deposit clarified the understanding of controls on gold mineralisation, and identified new areas for exploration within the Bullabulling gold deposit and regionally. Subsequent drilling of the Bullabulling gold deposit produced a sevenfold increase of the gold resource, transforming the goldfield in terms of future production potential. Gold endowment of the Bullabulling goldfield is 122 t Au.
Luketina, G, Franey, D, and Partington, G, 2017 "Using gravity to target gold at Tampia Hill, Western Australia". AusIMM NZ branch conference, Christchurch, 10 September – 13 September 2017.
The discovery of the Tampia Hill orogenic gold deposit in the wheatbelt of Western Australia has sparked interest in this under-explored region of the state. The deposit is hosted within a granulite facies greenstone belt, with mineralisation mostly hosted in mafic gneiss, which has been intruded by undeformed and unmetamorphosed granite. A lack of outcrop in the project area has meant that geophysics has been vital for interpretation of the geology. A recent gravity and magnetic survey has allowed the most detailed interpretation of the underlying lithology and structures to date, and has highlighted previously unknown areas of mafic gneiss, with a similar signature to that at Tampia Hill. In order to extract the most useful information from the survey, spatial statistical analyses were conducted on the gravity survey data. The analyses over the project area map features within the gravity data that can be used to identify areas of known gold mineralisation. The results confirm that the gravity data not only provides critical geological information, but will also allow the identification of high priority targets for future exploration using spatial data modelling techniques.
Nielsen, S H H, and Franey, D, 2017 "Downhole Logging in 3D Geology and Mineral Potential Modelling". AusIMM NZ branch conference, Christchurch, 10 September – 13 September 2017.
Logging of drillholes using wireline tools is an emerging methodology in mineral exploration that adds valuable data to exploration drilling. RC drilling is relatively cheap and quick, but it comes with the price of lost sample integrity and structural coherence. Wireline logging can cover this loss, by facilitating structural interpretations based on borewall imagery. Rock property data can also be recovered below the sampling resolution, such as optical televiewer (OTV) imagery, density, magnetic properties, natural gamma radiation and acoustic properties on cm and even mm scale. In the field, wireline logging will add just a few days to the drilling programme. A team of wireline technicians run their wireline down a recently completed drillhole using an assortment of tools depending on the requests of the client, at a cost amounting to only a few dollars per metre. The tools are oriented with magnetometers and accelerometers, enabling directional logging of geological features the drilling passed through. Combined with on-site logging of lithology and data from tools used in the field, wireline logging will enable exploration to take a significant step towards complete understanding of the prospect geology. In this paper we show downhole logging results from Tampia Hill, Western Australia, and how this work has been used to establish a structural framework and guide the creation of 3D geological and mineral potential models
Peters, K J, Partington, G A, Blevin, P L, Downes, P M, and Nelson, M D, 2017 "The Southern New England Orogen Mineral Potential Project". AusIMM NZ branch conference, Christchurch, 10 September – 13 September 2017.
he Southern New England Orogen (SNEO) in the northeastern part of New South Wales (NSW) is prospective for intrusion-related tin-tungsten, intrusion-related gold-bismuth-molybdenum-silver and orogenic goldantimony mineral systems. An initiative by the Geological Survey of NSW to conduct mineral potential modelling for these mineralisation styles in the SNEO has resulted in a comprehensive account of the mineral resource potential of the region. The Geological Survey of NSW has a successful strategy of providing high quality pre-competitive data that has been complemented and enhanced by the mineral potential mapping approach. Datasets including seamless basement geology, detailed attribution of faults, and igneous fertility that were created by the survey prior to modelling enabled an extensive number of variables be tested for relevance to each mineral system. The feedback from the data processing and spatial analysis allowed improvements to be made to the data and provided information on the relevance of the datasets to mineral exploration in the region. The outputs of the models are mineral potential maps that map the geological potential of the SNEO for each mineralisation style. The models will be used for land planning and advice purposes, technical resources for improved mineral system studies including global endowment estimations, and for promoting exploration in the SNEO through the generation of prospective targets. Due to the richness of the geological datasets in NSW it is likely that the technique, including the creation of high-quality datasets combined with mineral potential modelling, can be successfully applied to other mineralised regions within NSW.
Peters, K J, Partington, G A, McKenzie, C J, Hill, M P, Miller, A V M, and Nielsen, S H H, 2016 "A Review of Mineral Prospectivity Modelling in New Zealand During the Past 15 Years". Mineral Deposits of New Zealand Exploration and Research, AusIMM, 31, pg 53 – 60.
Prospectivity modelling has been used in New Zealand since 2002 by the government to promote mineral exploration programs. The models for orogenic and epithermal gold completed by Crown Minerals and the Institute of Geological and Nuclear Sciences for the government in 2002 and 2003 were undertaken to promote exploration activity in New Zealand. Since this time, at least 38 mineral prospectivity models have been completed, by industry and government, covering most of the hard rock mineralised regions onshore and nodular phosphate offshore on the Chatham Rise. In the last 15 years there have been advances in prospectivity modelling techniques, software capabilities, digital data availability and exploration targeting methods, all of which improve the effectiveness of prospectivity modelling as a tool for mineral exploration targeting. Future work should include:
- incorporating new data into existing models
- modelling new areas when data becomes available
- 3D prospectivity modelling modelling of other commodities such as coal, alluvial gold and irons
- infrastructure modelling and exploration effectiveness analysis.
Peters, K J, Partington, G A, McKenzie, C J, Miller AVM, Nielsen, S H H, 2016
"Mineral Prospectivity Modelling in New Zealand: Review and Future Perspectives". AusIMM NZ Branch Conference, Wellington, 3-6 September 2016
Mineral prospectivity modelling using geographic information systems (GIS) has been used in New Zealand since 2002 both by the government, to promote mineral exploration in New Zealand, and industry, to inform project acquisition and increase the efficiency of exploration programmes. Over the last 15 years at least 38 mineral prospectivity models have been completed in New Zealand covering most of the hard rock mineralised regions onshore as well as nodular phosphate offshore on the Chatham Rise.
Analysis of highly prospective targets generated from the models already completed in New Zealand provides important information about the mineral potential of the country. Onshore, highly prospective targets over a range of commodities cover only 0.5 percent of the total land area of New Zealand, significantly narrowing the search area for new mineral deposits. 83 percent of the targets occur outside public conservation land, and 45 percent of the targets are unpermitted at the time of writing, suggesting there is potential for increased exploration investment and for new discoveries to be made. Prospectivity modelling has had a measureable positive impact on exploration activity and project development in New Zealand over the last 15 years. Future work should include incorporating new data into existing models, modelling new areas when data becomes available, improving existing mineral occurrence datasets, 3D prospectivity modelling, modelling of other commodities such as coal, alluvial gold and ironsand, infrastructure modelling, and exploration effectiveness analysis.
Nielsen, S H H, Mckenzie, C, Miller, A, Partington, G, Payne, C, Puccioni, E, Stokes, M, Wildman, C, Falconer, R K H and Wood, R, 2015 "Chatham Rise nodular phosphate - Modelling the prospectivity of a lag deposit (off-shore New Zealand): A critical tool for use in resource development and deep sea mining". Ore Geology Reviews, 71:545-557.
After almost five decades of episodic exploration, feasibility studies are now being completed to mine the deep water nodular phosphate deposit on the central Chatham Rise. Weights of evidence (WofE) and fuzzy logic prospectivity models have been used in these studies to help in mapping of the exploration and resource potential, to constrain resource estimation, to aid with geotechnical engineering and mine planning studies and to provide background geological data for the environmental consent process. Prospectivity modelling was carried out in two stages using weights of evidence and fuzzy logic techniques. A WofE prospectivity model covering the area of best data coverage was initially developed to define the geological and environmental variables that control the distribution of phosphate on the Chatham Rise and map areas where mineralised nodules are most likely to be present. The post-probability results from this model, in conjunction with unique conditions and confidence maps, were used to guide environmental modelling for setting aside protected zones, and also to assist with mine planning and future exploration planning. A regional scale fuzzy logic model was developed guided by the results of the spatial analysis of theWofE model, elucidating where future exploration should be targeted to give the best chance of success in expanding the known resource. The development work to date on the Chatham Rise for nodular phosphate mineralisation is an innovative example of how spatial data modelling techniques can be used not only at the exploration stage, but also to constrain resource estimation and aid with environmental studies, thereby greatly reducing development costs, improving the economics of mine planning and reducing the environmental impact of the project.
Kreuzer, O P, Miller, A V M, Peters, K J, Payne, C E, Wildman, C, Partington, G A, Puccioni, E, McMahon, M E and Etheridge, M A, 2015 "Comparing prospectivity modelling results and past exploration data: A case study of porphyry Cu-Au mineral systems in the Macquarie Arc, Lachlan Fold Belt, New South Wales". Ore Geology Reviews, 71:516-544.
Mineral exploration is undertaken in stages, with each stage designed to get to the next decision point of whether or not to keep exploring a particular area based on the results at hand. As a general rule, each consecutive exploration stage is more expensive due to the progressively more drill- and study-intensive nature of the work required, in particular after discovery of a potentially economic mineral deposit. As such, the distribution of exploration activities and related expenditures essentially serve as a spatialmeasure of prospectivity as perceived by mineral exploration companies. In this study wecompare historic (1980 to 2002) porphyry Cu-Au exploration activities and expenditures in part of the Ordovician to Early SilurianMacquarie Arc, Australia's most significant porphyry province with total resources greater than 80 Moz of Au and 13 Mt of Cu, to prospectivity modelling results froma weights of evidence (WofE) model. The outcomes of this spatial and statistical comparison indicate that at 2002 the Macquarie Arc was by no means a mature exploration destination and that past exploration investment outside the main mining areas was not necessarily effective. Moreover, no spatial correlation was apparent between areas of higher exploration expenditure and greater geological potential. For example, of the 692 km2 of highly prospective ground covered by the exploration licences examined in this study, only 89 km2 (c. 13%) have been explored effectively in that they received some form of drilling. Interestingly, the remaining area (603km2 or c. 87%) had not yet been effectively tested. As such, our analysis confirmed that despite a greater 100 year exploration and mining history,much of the prospective groundwithin the study area remained untested. Taken as a whole, the results of our spatial and statistical comparison are important inputs for assessing the effectiveness of exploration investment and explanation maturity and, therefore, future exploration decisionmaking. The outcomes also have implications for strategic planning of future government legislation helping to manage and maximise the benefits from exploration investment.
Payne C E, Cunnigham F, Peters, K J, Nielsen S H H, Partington G A, Puccioni E, Wildman C, 2015 "From 2D to 3D: Prospectivity modelling in the Taupo Volcanic Zone, New Zealand". Ore Geology Reviews, 71:558-577.
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.
Nielsen S H H, Cunningham F, Hay R, Partington G A, Stokes M, 2015 "3D prospectivity modelling of orogenic gold in the Marymia Inlier, Western Australia" Ore Geology Reviews, 71:578-591
The Proterozoic Marymia Inlier is known for orogenic gold deposits along granite-mafic rock contacts within major bounding thrust planes, including the producing Plutonic mine. A 3D prospectivity model was built based largely on surface geology extended into the subsurface using geophysical data, confirmed by drill data when available. Because of the complexities of taking 2D data into 3D and the length of time to test spatial associations in 3D, a 2D weights of evidence prospectivity model was initially created to constrain the 3D predictive maps integrated into the 3D prospectivity model. The final 3D model used a ranked fuzzy logic technique, with the ranking adjusted from the 2D weights of evidence model that was used to constrain the development of 3D predictive maps. The study shows that 3D prospectivity modelling can be used to identify targets at significant depth and establish depths for drilling them.
Wildman, C, Puccioni E, Stokes, M A, and Schodde, R, 2015 "Enhancing regional and national economic development from mineral projects: The use of spatial analysis to inform on infrastructure deficit in Canada". AusIMM NZ branch conference, Dunedin, 31 August - 2 September 2015
A Canada National Infrastructure spatial analysis has been completed for the Prospectors and Developers Association of Canada (PDAC). The objective was to identify the Canadian districts where strategic investment in enhancing the infrastructure network could stimulate the development of new mines by reducing the overall capital costs of production. This was achieved by spatially analysing the relationship between infrastructure deficient regions and the location of significant, undeveloped mineral deposits. After compiling a comprehensive dataset of the existing infrastructure in Canada, the available information was classified and weighted based of their importance to mineral extraction. The most relevant datasets – including infrastructure, elevation and climatic data as well as cultural data such as distribution of population – have been combined using spatial modelling techniques to create a “remoteness” map of the country.
The “remoteness” map has then been compared with potential mining/advanced exploration projects in order to identify areas where strategic investment by provincial and federal government could stimulate new mineral development and therefore regional economic development. The completed spatial model has highlighted where investment would be most beneficial. Furthermore, a series of more specific cost-related maps have been produced for two categories of mineral commodities, precious minerals and base metals. The two categories differ in mining methods and quantities of minerals extracted; therefore requiring different types of infrastructure for operating. These additional models show the percentage increase of potential costs for building and maintaining a mining project related to the increase in remoteness. The results of the heat maps clearly identify regions where the enhancement of specific types of infrastructure could drastically decrease the overall costs of a precious mineral or base metal project and therefore encourage its development by making it economically feasible. The model results will allow the PDAC to work with appropriate government departments to prioritise the most prospective mining opportunities in infrastructure deficient areas and therefore efficiently propose a workflow of possible enhancements to local infrastructures to encourage the development of new mines in the identified areas.
Miller, A V M, Partington, G A, Kreuzer, O, Butera, K, Buckingham, A, and Ainoo, S, 2015 "Regional Prospectivity Modelling in Data-Poor Areas: The Kumasi Basin, Ghana". AusIMM NZ branch conference, Dunedin, 31 August - 2 September 2015
Here we present a case study of prospectivity modelling over a region with both data-rich and data-poor areas, in the Kumasi Basin, Ghana. Whilst a reasonable amount of geological, geochemical and geophysical data is available over much of the Asankrangwa Gold Belt, host of the large Nkran and Esaase gold deposits (measured, indicated and inferred resources >10 Moz Au), data availability over much of the remainder of the Kumasi Basin is generally poor and of much lower resolution. As part of a comprehensive prospectivity and targeting study undertaken by Corporate Geoscience Group for Asanko Gold, Kenex completed GIS-based prospectivity modelling using the weights of evidence (WoE) technique to delineate high priority targets for orogenic gold. WoE modelling provides a data-driven tool that combines relevant datasets, identifies anomalous thresholds in predictors of mineralisation and produces a map of geological potential.
Statistical methods ensure that when the final geological potential grid is created, areas with missing data coverage are not significantly down-weighted relative to anomalous areas. Areas of poor data coverage in the Kumasi Basin required creative examination to allow successful modelling. For example, Kumasi Basin orogenic deposits are often associated with broad zones of silicic alteration. Consequently, many deposits resist weathering and form topographic ridges, allowing analysis using detailed open-file DEM data. Ridges were extracted and attributed with scale, relative strength and orientation, all of which were tested for spatial correlation with known orogenic deposits. Another example involves limited coverage of available geophysical surveys. Scanned TMI image data was reclassified into a GIS and certain colour bands selected as most accurately representing TMI. Properties such as magnetic slope, a common predictor for orogenic mineralisation, could then be calculated. Many targets identified by the model were located in areas with high data density. By using data intelligently we have also identified targets in data-poor areas.
Nielsen, S H H, Falconer, R, and Wood, R, 2015 "Mineral Prospectivity Modelling as a Tool for Resource and Mine Development". AusIMM NZ branch conference, Dunedin, 31 August - 2 September 2015
Prospectivity models in the last ten years have been predominantly used to establish the distribution of potentially mineralised ground over large areas, generally to guide initial exploration programmes in regional and mine camp settings. This approach can also be applied to the mine scale to guide resource estimation, development of reserves, mine and environmental planning, project development and to extend mine life through discovery of new resources. The Chatham Rise phosphate deposit is used as an example of where the results from prospectivity mapping can be used to guide mine planning, help with resource optimisation and provide constraints for project development. In this example the prospectivity results were combined with environmental modelling to help with environmental planning and the avoidance of sensitive areas, as well as guide mine planning. Another example compares a feasibility study to a prospectivity model over the same area. Prospectivity is an indicator of potential mineralisation presence, if not necessarily directly correlated to the actual concentration of resource present. Thus prospectivity mapping can be used to guide resource estimation and steer future efforts of resource definition and upgrading. An effective way this can be done is by using the prospectivity equivalent of the resource lower cut-off value to indicate where mineralisation may potentially be present outside the established regions. Confidence and unique conditions grids can then be used to establish what types of data needs to be gathered and where, to increase the reliability of the result.
Miller, A V M, 2015 "Quantifying exploration effectiveness in the Lachlan Fold Belt, New South Wales". AusIMM NZ branch conference, Dunedin, 31 August - 2 September 2015
Payne, C E, 2015 "Predictive modelling of polymetallic nodule deposits in the Cook Island Exclusive Economic Zone". AusIMM NZ branch conference, Dunedin, 31 August - 2 September 2015
Payne, C E, Cunningham, F W, Wilkins, A J and Partington, G A, 2014 "Improvements on 2D modelling with 3D spatial data: Sn prospectivity of Khartoum, Queensland, Australia" AusIMM NZ branch conference, Hamilton, 24-27 August 2014
Auzex Exploration Limited owns a number of exploration tenements over the historically tin rich Khartoum area near Herberton, north Queensland, Australia and Kenex Ltd has completed both 2-dimensional prospectivity modelling and a 3-dimenional geological interpretation over this region. The initial 2-dimensional prospectivity model of intrusion related tin mineralisation is limited by the 2D nature of the data used, and regions of known Sn mineralisation were not identified, particularly in the contact zones of shallow dipping highly fractionated tin granites. To rectify this, a 3D geological model was created using Leapfrog Geo modelling software, and 3D spatial data has been projected to the surface topography and incorporated into an updated 2D prospectivity model of the region using ArcGIS software. The 2D and 3D models utilise newly compiled digital data including historical exploration data; geological data compiled from detailed geological mapping of north Queensland, academic literature and company exploration mapping; recent geophysical data collect by Fathom Geophysics Australia Pty Ltd; ASTER data analysed for alteration; and historical exploration geochemical data including rock-chip, stream sediment and soil sampling. The weights of evidence modelling technique was used to determine spatial correlations between known deposits and predictive maps in 2D, created from the available data, that represent each component of the currently accepted minerals systems model for intrusion related tin mineralisation defined for this project. The final updated 2D prospectivity model partially resolves the limitations of the initial 2D model, successfully identifying many of the areas originally missed.
Miller, A V M, Partington, G A, Nielsen, S H H, Peters, K J and Puccioni, E, 2014 "Exploration Targeting from Prospectivity Modelling of Multiple Deposit Types in the Lachlan Fold Belt, NSW" AusIMM NZ branch conference, Hamilton, 24-27 August 2014
Prospectivity modelling has been completed over the Lachlan Fold Belt, New South Wales, Australia, using the GIS based weights of evidence modelling technique to target porphyry Cu-Au, associated skarn Cu-Au, orogenic Au and VMS Au mineralisation. The Lachlan Fold Belt is a 700 km wide belt of Paleozoic accretionary terrains, stretching from Queensland to Tasmania. Porphyry and skarn mineralisation was associated with Ordovician shoshonitic magmatism, which was followed by Silurian regional metamorphism and deposition of orogenic gold deposits. Contemporaneous VMS-style mineralisation resulted in deposits in intra-arc rift basins of the Macquarie Arc. In preparation for the prospectivity modelling, lithological and structural data, extensive geophysical surveys and stream, drill-hole and rock chip geochemistry were used to create predictive maps that represent various parts of the mineral systems being modelled. Included in the models are maps that identify possible sources of heat and mineralised fluids, structures used for fluid migration, mineral trap zones, and outflow zones that may indicate a subsurface deposit. Prospectivity maps have been created for each mineralisation style and new areas of each deposit type located. The models have also independently identified areas of proven mineralisation, including Cadia, Northparkes, Woodlawn and other large producing mines. The prospectivity maps were reclassified to generate targets by delineating highly prospective areas from each model. Targets were compared and overlap examined among the four models, before further analysis of high priority targets. Single targets or clusters of targets were individually assessed by incorporating information such as tenure, geology, geochemistry and geophysical signature. Economic and risk factors were assessed and the targets ranked and mapped according to high and low exploration risk. Following this analysis, targets of interest can be highlighted as potential projects for acquisition, or used to prioritise new exploration data collection.
Cunningham, F W, Wilkins, A J, Payne, C E, Nielsen, S H H and Partington, G A, 2014 "Targeting tin mineralisation using "3D Common Earth Models" in the Khartoum region, North Queensland, Australia" AusIMM NZ branch conference, Hamilton, 24-27 August 2014
The use of modern day 3D GIS software packages such as GOCAD, GeoModeller and Leapfrog Geo has dramatically changed the way exploration targeting can be carried out compared to the last twenty years of using 2D Geographic Information System (GIS) for exploration. This is especially true in the last five years in which computer and GPS technology has developed to the stage where it is possible to digitally locate, accurately store, visualise and manipulate geological data in 3D at the scale of a mineral system, which is usually much greater than mine scale where most of the current 3D work is focussed. Most GIS can store, manage and manipulate data in 2D, with some able to visualise information in 3D. However, there are a number of packages that allow full 3D GIS functionality, including querying and modelling, allowing geologists to start exploration targeting in a 3D system. Auzex Exploration Limited owns a number of exploration tenements over the historically tin rich Khartoum area located near Herberton in North Queensland, Australia, exploring for Tin-Tungsten mineralisation. A 3D geological interpretation was created over a 60 km by 60 km region in Khartoum using Leapfrog Geo to improve targeting for tin systems adjacent and above buried granites and shallow dipping granite contacts, followed by 3D targeting using a Multi-Class index Overlay workflow of GoCAD Mining. The ranking of the 3D maps were based on a 2D prospectivity mapping exercise using the weights of evidence technique. By modelling geology and targeting in 3D, complex subsurface relationships and the correct vertical extents can be constrained. This will be invaluable for defining potential drill-hole targets.
Peters, K J, McKenzie, C J, 2013 "New Zealand Gold Potential - Using Mineral Prospectivity Modelling to Evaluate Gold-Bearing Mineral Systems in an Underexplored Country" World Gold Conference, Brisbane, 26-29 September 2013
New Zealand has an established history of gold production beginning with the gold rushes of the 19th century in the Coromandel, Nelson/Marlborough, West Coast and Otago regions. Despite this, the number of significant modern hard rock gold operations has been limited in recent years due to a lack of sustained exploration capital and not limited geological prospectivity. The New Zealand Government is actively encouraging explorers to invest in New Zealand through a series of targeted promotional visits, more importantly through the acquisition of precompetitive regional geophysical data. Data collection has been completed over the prospective Northland epithermal district and a large portion of the South Island’s west coast that is prospective for both orogenic gold and intrusive related gold. Analysis of new data has been an important component in aiding the generation of exploration targets from prospectivity modelling. Determining the prospectivity of an area involves reviewing all the available data and analysing it with respect to the most up-to-date mineral system model for the mineralisation style of interest. Using the weights of evidence modelling approach, the most prospective areas for epithermal gold-silver, orogenic gold and intrusion-related gold have been identified. The key exploration parameters relevant to each mineral system are first represented spatially and then statistically combined into a single prospectivity map. New potentially economic deposits could be found by focusing exploration on targets identified from these models. The prospectivity modelling approach can greatly reduce the risk involved in mineral exploration.
Payne, C E, Peters, K J, 2013 "Geochemistry in prospectivity modelling: investigating gold mineralisation in the Taupo Volcanic Zone, New Zealand" AusIMM NZ branch conference, Nelson, 25-28 August 2013
Nielsen, S H H, 2013 "New Insights into the Origin and Distribution of Phosphate Deposits on the Chatham Rise" AusIMM NZ branch conference, Nelson, 25-28 August 2013
Cunningham, F W, Peters, K J and Payne, C E, 2013 "3D prospectivity modelling - a new era in exploration targeting" AusIMM NZ branch conference, Nelson, 25-28 August 2013
The use of computers in the mineral industry has dramatically changed the way exploration targeting is carried out over the last twenty years. This is especially true in the last five years where computer and GPS technology has developed to the stage where it is possible to digitally locate, accurately store, visualise and manipulate geological data in three dimensions (3D) at the scale of a mineral system. These tasks are commonly carried out using a Geographic Information System (GIS), which has become as an important tool to a geologist as his hammer. Most GIS store, manage and manipulate data in two dimensions (2D), with some having the ability to visualise information in 3D. However, there are now a number of packages that allow full GIS functionality including querying and modelling in 3Dgiving geologists a tool to carry out exploration targeting in 3D. A regional scale weights of evidence 2D prospectivity model was developed for the Taupo Volcanic Zone in New Zealand to assess the potential for epithermal Au mineralisation. A number of prospective areas have been identified including the known Ohakuri hydrothermal deposit. While this model has been successful at identifying mineralised areas the 2D data that is used gives little understanding of what is happening below the surface. Because geology does not just operate in 2D, trying to visualise 3D geometries in 2D can be challenging in exploration targeting. The development of 3D GIS such as GoCad and Geomodeller now give us the tools and techniques to use fuzzy logic and weights of evidence techniques for targeting in mineral exploration in 3D. A prospectivity modelling exercise using the weights of evidence modelling technique (developed by Bonham-Carter of the Canadian Geological Survey), was completed over the Ohakuri epithermal gold deposit in both 2D and 3D.
McKenzie, C J, Wood, R and Falconer, R, 2013 "From exploration to extraction: The consequences of resource morphology for mining operation on the Chatham Rise" AusIMM NZ branch conference, Nelson, 25-28 August 2013
Substantial consideration has been given to the implications that the morphology of the Chatham Rise deposit will have on mining operations. The glacio-tectonic processes involved in the distribution of nodules on the rise have in several areas been quite significant. The recent cruises by Chatham Rock Phosphate Limited (CRPL) have collected data which has affirmed the assumptions previously made and catered for in historic resource estimations. The deformation and displacement of the phosphorite during glacial periods and the redistribution of the mobile sand during interglacial periods is interpreted to have produced a highly variable pattern of phosphorite concentration (kg phosphorite/m2) and coverage (% phosphorite/sample weight). The phosphorite resource probably has a significant spatial variability at a scale of tens of metres. Results of recent surveys show phosphorite-rich patches alternating with phosphorite-poor areas at distances of less than 20 m. The high spatial variability of the deposit has had a bearing on how historical information for the project has been regarded and integrated with the recent exploration approach and data collection process. This coupled with the proposed extraction tool has influenced the size, nature, extent and siting of the proposed mining blocks.
Partington, G A, 2013 "Taking SDM from the 2D to 3D world" FUTORES Conference: Future understanding of tectonics, ores, resources, environment and sustainability, Townsville, 2-5 June 2013.
The use of computers in mineral exploration in the last twenty years has changed the way we carry out exploration targeting dramatically. This is especially true in the last five years where computer and GPS technology has developed to the stage where it is possible to digitally locate, accurately store, visualise and manipulate geological data in 3D at the scale of a mineral system. These tasks are commonly carried out using a Geographic Information System, which has become as an important tool to a geologist as his hammer. Most GIS store, manage and manipulate data in 2D, with some having the ability to visualise information in 3D. However, there are now a number of packages that allow full GIS functionality including querying and modelling in 3D. This now gives geologists a tool to carry out exploration targeting in 3D. Exploration targeting using Fuzzy Logic and Weights of Evidence techniques is becoming more commonplace in the industry and is being used particularly by government organisations to manage their resources. However, one of the weaknesses of the work to date is that these studies are carried out in 2D, with an approximation of 3D provided by geophysical and drilling data projected to a 2D plane. Geology does not operate in the 2D world and many geological problems relate to 3D geometries and this is particularly true for exploration targeting. The development of 3D GIS such as GoCad and Geomodeller now give us the tools and techniques to use Fuzzy Logic and Weights of Evidence techniques for targeting in mineral exploration in 3D. However, several issues remain to be resolved before these tools become effective and used routinely by the industry. The most important issue is that of training, with graduate geologists not receiving appropriate training in the use of GIS to solve geological problems, particularly related to exploration. The other important problem relates to data availability and data quality, which was an issue for 2D models, but is even more of an issue for work in 3D. Consequently, we are now at the stage where computing power and modelling techniques have overtaken the availability of high quality 3D geological data and trained geologists to maximise their use.
Peters, K J, Miller, A V M, 2013 "Exploration targeting from prospectivity modelling in the Lachlan fold belt, NSW" FUTORES Conference: Future understanding of tectonics, ores, resources, environment and sustainability, Townsville, 2-5 June 2013.
Employing an effective exploration targeting method is important when looking for economic concentrations of minerals in a particular country or region. Methods for exploration targeting include geophysical or geochemical anomalies and intuitive decision making. Alternatively, prospectivity modelling allows for a complete picture of the economic potential of a country or region if all relevant mineralisation styles are considered. Prospectivity models can be reclassified to define high priority targets that can be used to focus an existing exploration programme or to pick up new ground. We present an example of this exploration targeting approach using the Lachlan Fold Belt in NSW. Prospectivity models have been completed over the Lachlan Fold Belt for porphyry Cu Au, skarn, VMS Cu, and orogenic Au mineralisation styles. The models use the mineral systems approach to determine key predictive variables that define each mineralisation style using the available data. Targets that delineate highly prospective areas have been defined from each model. The targets either represent existing prospects or mines or areas where new mineralised systems could be discovered with further exploration and development. A number of tools can be used to analyse the targets. Economic and risk factors can be assessed and the targets can be sorted and mapped according to positive and negative exploration risk. Single targets or clusters of targets can be individually assessed providing information such as tenure, geology, geochemistry and magnetic signature. Following this analysis, targets of interest can be highlighted as potential projects for acquisition, or an appropriate exploration programme prepared.
Miller, A V M, Peters, K J, 2013 "Comprehensive prospectivity analysis of the Lachlan fold belt in NSW using the mineral systems approach" FUTORES Conference: Future understanding of tectonics, ores, resources, environment and sustainability, Townsville, 2-5 June 2013.
Prospectivity modelling has been completed over the Lachlan Fold Belt (LFB) in NSW Australia, using the GIS based weights of evidence modelling technique and porphyry Cu Au, skarn, orogenic Au and VMS Cu mineral system models. The LFB is a 700 km wide belt of deformed Paleozoic marine sedimentary and mafic volcanic rock stretching from Queensland to Tasmania. It dominates eastern NSW and hosts several large producing gold deposits including Cadia and Northparkes. Lithological and structural data from the NSW Geological Survey was combined with stream, drill-hole and rock chip geochemistry and extensive geophysical surveys. The data was used to create predictive maps for each of the four models, constrained by the mineral systems concept which defines the parts of the mineralisation system that are critical to the ore-forming process. Included in all models are layers that identify possible sources of heat and mineralised fluids, structures used for fluid migration, mineral trap zones, and outflow zones that may indicate a subsurface deposit. Training points were chosen from known areas of mining or exploration specific to the relevant mineralisation style (Fig. 1). Prospectivity maps have been created for each mineralisation style giving a comprehensive understanding of the gold and copper mineralisation over the LFB in NSW. Known areas of each deposit type have been identified along with new areas that have potential for porphyry, skarn, orogenic or VMS deposits. These prospectivity maps and exploration GIS create a valuable tool to accelerate exploration and identify new opportunities in NSW’s most productive goldfield.
Partington, GA, 2012 "Developing Wind and Mineral Exploration Models using GIS for Project Development in Argentina" Argentina Mining Conference, San Juan, 31 August-2 September 2012.
Kenex in partnership with Emprendimientos Energeticos y Desarrollos S.A (EEDSA) have recently completed a number of strategic business development projects in Argentina to develop wind energy and mineral resources. A partnership was developed with EEDSA in 2010 to explore for and develop wind energy opportunities in Argentina using Kenex’s recently developed wind prospecting techniques. These techniques have been successfully used to map wind farm locations in New Zealand and rank each site according to its economic potential. After a year of data collection and modelling, which has successfully mapped potential wind farm sites in a number of provinces in Argentina, the partnership decided to expand into mineral exploration. Spatial Data Modelling techniques were used to map potential mineral exploration opportunities for gold, copper, base-metals, tin, tungsten and uranium at a regional scale in Argentina and Chile. Regional scale prospectivity models were developed for Argentina and Chile to identify prospective areas for a variety of metals and mineralisation styles. Fuzzy logic techniques were used to develop the wind prospectivity maps and Weights of Evidence modelling techniques were used to develop the mineral potential maps in Argentina and Chile. The models have successfully identified areas that are prospective for wind energy and gold, copper and silver and have also identified areas where new mineralised systems could be discovered with further exploration and development. Economic and risk factors will be included and target areas can then be sorted and mapped according to positive and negative exploration risk. A similar analysis will be carried out for the wind targets. This will lead to the development of an Argentina wide database of prioritised metal and wind energy targets for exploration and development. The prioritised targets will then be combined with social and logistical factors to highlight projects for acquisition. The regional targeting work for both wind energy and mineral resources has now been completed and the partnership is in the process of developing a number of business.
Puccioni, E, 2012 "Predicting the wind: Wind Farm prospecting using GIS" Esri Asia Pacific User Conference, Auckland, 5-7 November 2012.
Wildman, C and Peters, K J, 2012 "Using predictive modelling to aid planning in the mineral exploration and mining sector - a case study using the Powelliphanta Land Snail" AusIMM NZ branch conference, Rotorua, 26-29 August 2012.
The weights of evidence spatial data modelling technique has been used to create a predictive map that identifies possible locations of alpine Powelliphanta land snails in the South Island of New Zealand. This technique is commonly used in the mineral exploration industry to identify locations most likely to host mineralisation and is becoming more widely used in environmental fields as data becomes available in a digital form. Climatic, soil, topographic, and botanical data used in the model came from various organisations including NIWA and Landcare Research. The model uses the known locations of five Powelliphanta “taxa” that occur in high elevation, isolated alpine habitats to find other areas that may support similar Powelliphanta populations. The weights of evidence technique allows data to be assessed and weighted according to how great its influence is in relation to the current known locations of Powelliphanta snails. The most important variables identified from this spatial analysis were combined to produce a map showing the most likely places for Powelliphanta snails to be found. The resulting predictive model for snail habitat locations shows that mountain ranges in north-western part of the South Island have the highest probability of finding Powelliphanta land snails. It also shows that high altitude, low temperature and high rainfall condition are favoured by the snails. The model has been validated in the field and some areas not covered by the training points that were classified as highly probable by the model have recorded sightings of snails. Knowing the locations of species that will be affected, as well as knowing the potential relocation sites could help facilitate decision making during mineral exploration and mine planning.
Puccioni, E, 2012 "Energy in the wind: integrating the transmission network for a better approach to wind farm prospecting" New Zealand Wind Energy Association Conference, Hamilton, 2-4 April 2012
The availability of suitable transmission grid connectivity is quickly becoming a key factor for developing new wind farms globally. While wind speed remains the most important requirement for a successful wind farm along with other key parameters such as suitable terrain, current land use and distance from populated areas which are essential for site selection; a good grid connection is a significant factor in determining the economics pre-construction and future profitability of the wind farm. In the past three years, Kenex and Aurecon have developed advanced spatial modelling techniques that combine wind speed and direction, advanced terrain analysis, land use and social acceptability parameters to define the extent of potential wind farms at regional and country-wide scales. Our modelling has been successfully used by New Zealand developers to quickly and effectively target new wind farm opportunities and define the potential extent of an individual wind farm. Kenex and Aurecon have now refined the spatial modelling by integrating grid connection variables so as to identify not only the most suitable sites for a wind farm, but also which sites may potentially have the best available connections to the grid, and subsequently more preferable project economics.
Wildman, C. and O'Donnell, R.J., 2011 "Prospectivity Modelling of Seafloor Massive Sulphide (SMS) Deposits in the Kermadec Arc and Colville Ridge Regions". 40th Annual Conference of the Underwater Mining Institute, 14-18 September 2011, in Hilo, Hawai'i.
Prospectivity modeling of seafloor massive sulphide (SMS) deposits has been completed over the Kermadec Arc-Colville Ridge area using the GIS based weights of evidence and fuzzy logic modeling techniques. SMS deposits are the current equivalent of ancient onshore volcanogenic massive sulphide (VMS) ore deposits. These high-grade deposits are formed on the seafloor and commonly consist of a black smoker and metal rich sediment mound complex resulting from the discharge of hydrothermal fluids (up to 400°C) from fractures on the seafloor. Metal sulphides are continuously precipitated in response to mixing of high-temperature hydrothermal fluids with ambient seawater. Accumulation of metal sulphides has led to SMS deposits being potentially major sources of copper, zinc, lead and other metals such as gold, silver, which to date remain untapped. Modeling of SMS deposits was undertaken to illustrate the power of GIS modeling for seafloor resource evaluation and how it can be used to quickly identify and rank in terms of the most likely prospective areas of the seafloor where new SMS deposits might exist. The mineral deposit modeling was constrained by the mineral systems concept which defines those parts of a mineralisation system that are critical to the ore-forming process. The deposits are typically formed in extensional tectonic settings, including both submerged tectonic margins and sea-floor spreading. Volcanic vent systems and underlying dykes, stocks and sills are the sources of heat that are responsible for converting sea water drawn down through fractures in the oceanic crust into an ore-forming hydrothermal fluid. This fluid is then capable of leaching metals and elements from surrounding footwall rocks, which are then transported upwards via the convection of hydrothermal fluids. The ore materials are then precipitated within the black smoker field as massive sulphides due to the mixing of high-temperature (250-400°C), metal-rich hydrothermal fluids with cold (about 2°C) oxygen bearing seawater. Prospectivity modeling is done by compiling all the relevant data and integrating it in a way the matches the mineral system being modeled and combining them into a single mineral potential map. The commercial value of modeling from the exploration sense is that it enables more effective data management and data use, it aids decision making (focus of time, effort and expenditure) and it identifies where and what type of additional data should be collected. The modeling results can also aid government agencies from a planning perspective for areas such as mineral rights allocation, research funding direction, environmental planning and long term economic strategy regarding mineral development.
Hughes, S.L.M., 2011. "Genesis of the Chatham Rise Phosphorite; an interpretation from current literature". AusIMM Conference, Queenstown, 27-30 August 2011.
A synthesis of new ideas from papers relating to the genesis of the Chatham Rise phosphorite deposit is presented. Since the Sonne and Valdivia Cruises in the late 1970's and early 80's, little has been contributed to further define, quantify or explain the Chatham Rise phosphorite deposit. There have been, however, many advances in geochemistry, paleo-geography, paleo-oceanography and paleo-climatology which have contributed to understanding the genesis of phosphorite deposits worldwide. Recent oil and gas exploration in the Great South and Canterbury Basins has resulted in increased seismic coverage which has yielded in new insights into the deformation sequence on New Zealand's continental shelf marginal out in to the adjoining deep water basins. It is proposed that the Miocene southern ocean, open shelf, replacement type phosphorite deposits (which include the Chatham Rise phosphorite) were formed in response to tectonic movements, the subsequent erosion of the ancient super continent of Gondwana and the migration of ocean fronts in response to changing ocean topography. It follows that a reconstruction of paleo-geography and paleo-oceanography adjacent to the Gondwana supercontinent will provide insight into the development of this large phosphorite resource in time and space.
O'Donnell, R.J. and Partington, G.A., 2011 "Resource assessment using GIS modelling of orogenic gold mineralisation potential in New Zealand" . AusIMM Conference, Queenstown, 27-30 August 2011.
Prospectivity modelling of orogenic gold mineralisation has been completed over New Zealand using the GIS based weights of evidence modelling technique. New Zealand orogenic gold deposits are restricted to the South Island and lower North Island and are divided into two groups (Paleozoic and Mesozoic) based on their age and host rock association. Modelling of Paleozoic and Mesozoic orogenic gold deposits was undertaken to illustrate the power of GIS modelling in regional and nationwide resource evaluation and how it can be used to quickly identify and rank in terms of prospectivity areas of land where new orogenic gold deposits might exist. The mineral deposit modelling was constrained by the mineral systems concept which defines those parts of a mineralisation system that are critical to the ore-forming process. Both of the New Zealand gold models identified possible sources of metals in the region, structures that could be used for fluid migration, mineral trap zones ideally suited to host a mineral deposit, and outflow zones that may indicate a subsurface deposit. The models were validated against known areas of historical gold mining such as the Reefton deposits (Paleozoic) and Macraes Flat (Mesozoic). Two prospectivity maps showing areas favourable for Paleozoic and Mesozoic orogenic gold formation were produced. The prospectivity modelling successfully identified known areas for both types of orogenic gold mineralisation as well as several new localities not currently covered by existing tenements. The spatial modelling techniques used here can be applied elsewhere to evaluate resource potential, whether for gold, or any other land based resource, and can help planners and land owners manage future developments and their assets more effectively. Both models supersede those undertaken in 2002 by Crown Minerals and GNS Science under the purview of Dr Greg Partington (now Director of Kenex Ltd.). The new models were re-run due to the addition of new data and new modelling techniques and appear to have much better definition and are better for targeting at a prospect scale.
Hill, M. P. and Peters, K. J., 2010. "Resource assessment using GIS modelling of orogenic gold mineralisation and wind energy potential in Wellington, New Zealand". Australasian Institute of Mining and Metallurgy Conference Volume, New Zealand Branch Annual Conference, Auckland.
Prospectivity modelling of orogenic gold mineralisation and ideal locations for wind farm development has been completed over southwest Wellington in New Zealand. This modelling used a combination of the GIS based weights of evidence and fuzzy logic techniques. These models were undertaken to illustrate the power of GIS modelling in regional resource evaluation and how they can be used to quickly identify areas of land which should be considered for wind farm development or those where new gold deposits might exist. The mineral deposit modelling was constrained by the minerals systems concept which defines those parts of a mineralisation system that are critical to the ore-forming process. The Wellington gold model identified possible sources of metals in the region, structures that could be used for fluid migration, mineral trap zones ideally suited to host a mineral deposit, and outflow zones that may indicate a subsurface deposit. Similarly, the Wellington wind farm model identified ideal sites to develop a wind farm using elements critical for successful turbine placement such as wind speed, terrain, sources of air turbulence, access and land use. The models were validated against known areas of historical gold mining such as at Terawhiti and the turbine locations of Meridian Energy's new West Wind development. The modelling clearly shows that the resource potential in southwest Wellington is greater for wind energy especially after consideration of potential archaeological and environmental restrictions which may rule out key areas of possible orogenic gold mineralisation identified by the model. The spatial modelling techniques used here can be applied elsewhere in New Zealand to evaluate resource potential, whether for wind, gold, or any other land based resource, and can help planners and land owners manage future developments and their assets more effectively.
Partington, G.A. 2010 "Developing Models using GIS to Assess Geological and Economic Risk: An Example from Mineral Exploration in Oman for VMS Copper Gold Mineralisation." Ore Geology Reviews Volume 38 No.3, pg 197-207.
It is important to understand the financial risk involved in any business venture and recent economic conditions make this even more critical. There are a variety of tools and techniques that when used with modern GIS and the mineral system concept allow sophisticated economic risk analysis to be carried out, including assessing uncertainty. A weights of evidence model for VMS copper-gold mineralisation was created for the northern part of the Semail Ophiolite Belt in Oman and this has been used in conjunction with economic modelling to target, prioritise and plan follow-up exploration. Individual predictor themes of geology, geochemistry and geophysical data were combined into a single predictive map for VMS copper-gold mineralisation. The immediate benefits of carrying out this type of analysis include effective data compilation, quality control of digital data, understanding of critical geological factors to be used in follow-up exploration, ranking of prospects, prioritising exploration, exploration budgeting and management, understanding of risk and cost reduction. The prospectivity model identified 79 targets above an upper threshold in the study area. Nine of the targets are known historic mines or current operations, 11 of the targets are known undeveloped prospects and 59 of the targets are new unexplored prospects. The prospectivity model was not only used to target, but also used to plan new exploration programs to collect missing data that could add the most value to developing the target. Economic factors were developed for each of the targets identified by the modelling to allow a more complete understanding of the exploration risk. This allows targets with differing geology, amounts of metal and economic factors to be compared, ranked and prioritised. An exploration risk value was calculated by combining the geological probability values with the economic parameters so that positive exploration risk values were considered to be potential investment targets whereas targets with negative risk values were considered being more of a gamble. There are twenty-six targets in the study area with positive exploration risk values, which not only confirm the study areas' prospectivity, but also economic potential. The work in Oman confirms the potential for new discoveries in the region, which even at low copper prices still make attractive exploration targets.
McKenzie, C.J., Wildman, C., Puccioni, E. 2010 "Predictive modelling for environmental management and mineral exploration - potential applications for the marine minerals industry" Underwater Mining Institute Conference, Gelendzhik, Russia, 4 - 6 Otc 2010.
Deep sea mineral exploration has progressed significantly in the past few years, however it remains a nascent industry when compared to terrestrial mineral exploration and mining and the offshore petroleum industry. Given that in general marine exploration is more costly than terrestrial exploration the ability to focus exploration efforts and funds should be highly desirable to those companies involved. Similarly, the detailed understanding and distribution of species or habitats in the marine environment in many areas which coincide with prospective minerals deposits is often limited. Predictive modelling could therefore be a valuable tool for aiding the management of both facets of a marine minerals project. Although a GIS is a perfect way of visualising data and producing maps from that data, GIS also allows you to create new data through using statistically based gridding techniques or predictive maps using spatial data modelling techniques. This modelling is where businesses can really add value, using their data more effectively rather than just passively using it to generate maps and figures. Basic statistical gridding allows you to predict unknown values from within a single layer such as topography, bathymetry, geochemistry, vegetation, hydrology, water temperature or climate data. However the real power of GIS is when spatial modelling is applied to combine several layers to predict outcomes based on probability such as mineral prospectivity, agricultural sustainability, geotechnical risk, environmental risk, and onservation planning. Adapting the technique for locating or ranking prospective seafloor massive sulphide or manganese nodule targets or for aiding baseline and detailed environmental planning are some of the possible applications for predictive modelling for the marine minerals industry.
Partington, G. A. 2010. "Exploration targeting using GIS: more than a digital light table." GeoComputing Conference, Brisbane, 29 Sept - 1 Oct 2010.
The use of computers in mineral exploration in the last twenty years has dramatically changed the way we carry out exploration targeting (e.g. Bonham-Carter, 1994; Bonham-Carter et al., 1988; Mihalasky, 2001; Rattenbury and Partington, 2003; Partington and Sale 2004; Partington 2009; Carranza, 2009). This is especially true in the last five years where computer and GPS technology has developed to the stage where it is possible to digitally locate, accurately store, visualise and manipulate geological data at the scale of a mineral system. These tasks are commonly carried out using a Geographic Information System (GIS), which has become as an important tool to a geologist as his hammer. The aim of this paper is to provide a brief review of the techniques available to explorers using GIS and discuss the advantages and problems associated with using GIS techniques for exploration targeting.