Global Mineral Resource Assessment: Summary simulation results for estimates of amounts of copper in undiscovered porphyry copper deposits
Dates
Publication Date
2018-01-24
Start Date
2008
End Date
2016
Citation
Hammarstrom, J.M., Zientek, M.L. and Parks, H.L., 2018, Global Mineral Resource Assessment: Summary simulation results for estimates of amounts of copper in undiscovered porphyry copper deposits: U.S. Geological Survey data release, https://doi.org/10.5066/F70K26Q4.
Summary
In response to the growing demand for information on the global mineral-resource base, the U.S. Geological Survey (USGS) completed assessments for undiscovered resources of selected types of mineral deposits (https://minerals.usgs.gov/global). This data release tabulates data for simulations of amounts of copper resources in undiscovered porphyry copper deposits that were done for the Global Mineral Resource Assessment. For this assessment, 163 areas (permissive tracts) in 7 regions of the world that may contain porphyry copper deposits that had sufficient information to make a quantitative assessment of undiscovered copper resources were considered. Probabilistic estimates of numbers of undiscovered deposits were made for each tract. [...]
Summary
In response to the growing demand for information on the global mineral-resource base, the U.S. Geological Survey (USGS) completed assessments for undiscovered resources of selected types of mineral deposits (https://minerals.usgs.gov/global). This data release tabulates data for simulations of amounts of copper resources in undiscovered porphyry copper deposits that were done for the Global Mineral Resource Assessment. For this assessment, 163 areas (permissive tracts) in 7 regions of the world that may contain porphyry copper deposits that had sufficient information to make a quantitative assessment of undiscovered copper resources were considered. Probabilistic estimates of numbers of undiscovered deposits were made for each tract. These estimates were combined with grade and tonnage models in a Monte Carlo simulation to produce probabilistic estimates of amounts of copper in metric tons that could be contained in each permissive tract. The data were processed using the EMINERS computer program (Duval, J.S., 2012, Version 3.0 of EMINERS—Economic Mineral Resource Simulator: U.S. Geological Survey Open-File Report 2004–1344, http://pubs.usgs.gov/of/2004/1344) as part of a global mineral resource assessment. A GIS of the permissive tracts and selected data are available in Dicken, C.L., Dunlap, Pamela, Parks, H.L., Hammarstrom, J.M., and Zientek, M.L., 2016, Spatial database for a global assessment of undiscovered copper resources: U.S. Geological Survey Scientific Investigations Report 2010–5090–Z, 29 p., and GIS data, available at http://dx.doi.org/10.3133/sir20105090Z. In order to aggregate the simulations for each region and for the globe, it is necessary to consider the attributes of the permissive tracts. The undiscovered deposit estimates and the results of Monte-Carlo simulations are spatially extensive attributes of each permissive tract. Therefore, the estimate applies to the entire tract. The probability distributions of undiscovered metal from multiple mineral-resource assessments can be aggregated into a single result. However, the degree of association (dependencies) between geologically based assessment regions and tracts must be understood before aggregating assessment results. The degree of association specified affects the spread of the functions because the variance of the combined distribution is affected by the dependency between the random variables. Aggregation of simulation results can be done assuming complete dependence, independence, or some measure of correlation between permissive tracts. We aggregated the porphyry copper assessment results using two end-member assumptions: (1) complete dependence within a region and throughout the globe and (2) independence of each permissive tract relative to another permissive tract. EMINERS produces 4,999 simulations for each tract sorted by amount of copper. The sorted data for each simulation are summed to produce new distributions that represent the aggregated results for each region and for the globe assuming complete dependence. The same data are randomized by resorting the data to produce randomized distributions of simulation results for each tract. These randomized distributions were then summed to produce new regional and global distributions assuming total independence. Summary statistics were computed for both aggregation methods. The population means for sorted and randomized aggregated results are the same; however, the standard deviations and other statistical measures differ. This data release tabulates input and output data for simulations of amounts of copper resources in undiscovered porphyry copper deposits that were done for the Global Mineral Resource Assessment. The data release includes 5 child items, as follows: (1) Permissive tracts and input data.csv, (2) Simulation results_sorted.csv, (3) Simulation results_randomized.csv, (4) Simulation results_aggregated by regions.csv, and (5) Summary statistics by region.csv.
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Related External Resources
Type: Related Primary Publication
Hammarstrom, J.M., Zientek, M.L., Parks, H.L., Dicken, C.L., and the U.S. Geological Survey Global Copper Mineral Resource Assessment Team, 2019, Assessment of undiscovered copper resources of the world, 2015: U.S. Geological Survey Scientific Investigations Report 2018–5160, 619 p. (including 3 chap., 3 app., glossary, and atlas of 236 page-size pls.), https://doi.org/10.3133/sir20185160.
Data were obtained to estimate the amounts of copper that could be present in undiscovered porphyry copper deposits throughout the world to inform mineral resource planning.
