Publications
Kenex co-founder Greg Partington and other members of the Kenex team have kept up an incredible track record of publishing papers in conference proceedings and scientific journals since Kenex was founded. You can read them here.
Mineral Potential Mapping for Pre-Competitive Data Delivery in NSW Zone 54
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.
Using gravity to target gold at Tampia Hill, Western Australia
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.
Downhole Logging in 3D Geology and Mineral Potential Modelling
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
The Southern New England Orogen Mineral Potential Project
The 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.
Bullabulling goldfield
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.
Greenbushes tin, tantalum and lithium deposit
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.
Mineral Prospectivity Modelling in New Zealand: Review and Future Perspectives
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.
A Review of Mineral Prospectivity Modelling in New Zealand During the Past 15 Years
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.
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
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.
3D prospectivity modelling of orogenic gold in the Marymia Inlier, Western Australia
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.
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
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.
From 2D to 3D: Prospectivity modelling in the Taupo Volcanic Zone, New Zealand
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.