Mineral Resource Assessment Research Articles

An attempt at assessment of mineral resources

An attempt at assessment of mineral resources

Application of 3‐D Geoscience Modeling Technology for the Estimation of Solid Mineral Reserves

Abstract:Applying new approaches, methods, and technologies for the estimation of reserves can effectively improve the efficiency and accuracy of assessments of solid mineral resources. After analyzing the development of 3‐D geoscience modeling technology (3‐D GMT), this paper discusses the application of 3‐D GMT for the estimation of solid mineral reserves, emphatically introducing its workflow and two key technologies, 3‐D orebody surface modeling, and property modeling. Moreover, the paper analyzes the limitations of traditional methods, such as the section method and geological block method, and points out the advantages of 3‐D GMT: building more accurate 3‐D orebody models, expressing the internal inhomogeneous attributes of an orebody, reducing the potential for errors in the estimation of reserves, and implementing dynamic estimations of reserves.

From geochemical prospecting to international geochemical mapping: a historical overview

This paper provides a history of the development of regional geochemical mapping. Modern geochemistry was born in the Soviet Union in the 1930s, and the basic methodologies for regional mapping had been developed by the late 1960s, with important extensions being made in the 1980s. The paper records the development of regional geochemical surveys, or mapping, in the context of spatial scale and transition from a mineral exploration and resource assessment tool to an environmental mapping exercise supporting multi-disciplinary research. Attention is drawn to the role of the International Geological Correlation Program's Projects 259 and 360, and the continuing role of the International Union of Geological Sciences, in providing an international focus and dimension to global geochemical mapping. The paper closes with a section on some of the current research issues, opportunities and challenges for regional geochemical mapping.

Quantitative Prediction for Deep Mineral Exploration

On reviewing the characteristics of deep mineral exploration, this article elaborates on the necessity of employing quantitative prediction to reduce uncertainty. This is caused by complexity of mineral deposit formational environments and mineralization systems as increase of exploration depth and incompleteness of geo-information from limited direct observation. The authors wish to share the idea of “seeking difference” principle in addition to the “similar analogy” principle in deep mineral exploration, especially the focus is on the new ores in depth either in an area with discovered shallow mineral deposits or in new areas where there are no sufficient mineral deposit models to be compared. An on-going research project, involving Sn and Cu mineral deposit quantitative prediction in the Gejiu area of Yunnan Province, China, was briefly introduced to demonstrate how the “three-component” (geoanomaly-mineralization diversity-mineral deposit spectrum) theory and non-linear methods series in conjunction with advanced GIS technology, can be applied in multi-scale and multi-task deep mineral prospecting and quantitative mineral resource assessment.

Mineral Resource Prediction and Assessment of Copper Multi-mineral Deposit Based on GIS Technology in the North of Sanjiang Region, China

On the basis of the multi-information on geology, geophysics, geochemistry, and remote sensing, mineral resource prediction and assessment is one of the keystones and popular topics in quantificational geosciences both in China and abroad, for it can not only be used to extract metallogenetic information and delineate metallogenetic targets, but provide important data for the quantitative assessment of mineral resources. This article takes the northern part of Sanjiang region in the south of Qinghai Province, China, as a case study area. On the basis of the conventional mineralized factors of mineral resource prediction and assessment, combined with the research on post-ore change and preservation, a new insight into mineral resource prediction and assessment, in terms of regional mineralization, change, and preservation factors, is built on account of the features of deposits at high altitudes, big slopes, emergence in surface, and denudation in the study area. According to the 24 copper complex deposits and geological settings in the study area, 29 variations, including mineralized factors, change factors, and preservation factors have been extracted by Geographic Information System (GIS) technology. To show the effect of the new insight, two mineral resource prediction models have been built with the 29 variations and 20 mineralized variations, respectively. Weight-of-evidence modeling is applied to map copper complex potential areas in this study area. The posterior probability maps of copper complex deposits delineated by weights of evidence method are made by contrasting mineralized factors with mineralization, and also changed factors with preservation factors. The results of the latter is better than that of the former: on one hand, the latter eliminates the nonmineralized area that is produced by glacier, water, or wind denudation; on the other hand, it can delineate mineral prospects that have concealed mineralized stratum or magma.

Non-Linear Theory and Power-Law Models for Information Integration and Mineral Resources Quantitative Assessments

Singular physical or chemical processes may result in anomalous amounts of energy release or mass accumulation that, generally, are confined to narrow intervals in space or time. Singularity is a property of different types of non-linear natural processes including cloud formation, rainfall, hurricanes, flooding, landslides, earthquakes, wildfires, and mineralization. The end products of these non-linear processes can be modeled as fractals or multifractals. Hydrothermal processes in the Earth’s crust can result in ore deposits characterized by high concentrations of metals with fractal or multifractal properties. Here we show that the non-linear properties of the end products of singular mineralization processes can be applied for prediction of undiscovered mineral deposits and for quantitative mineral resource assessment, whether for mineral exploration or for regional, national and global planning for mineral resource utilization. In addition to the general theory and framework for the non-linear mineral resources assessment, this paper focuses on several power-law models proposed for characterizing non-linear properties of mineralization and for geoinformation extraction and integration. The theories, methods, and computer system discussed in this paper were validated using a case study dealing with hydrothermal Au mineral potential in southern Nova Scotia, Canada.

Mineral Potential Modelling for the Greater Nahanni Ecosystem Using GIS Based Analytical Methods

Mineral potential within the Greater Nahanni Ecosystem (GNE) was modelled in a Geographic Information System (GIS) for four different deposit types: (1) SEDEX (stratiform shale-hosted sedimentary exhalative Zn–Pb–Ag), (2) ‘Carbonate-Fault’ (carbonate-hosted zinc–lead–silver associated with major faults), (3) ‘Intrusion-Related’ (includes skarn, rare metals and gemstones) and (4) Carlin-Type gold as lode and/or derived placer deposits. This mineral potential modelling study integrates data collected during the Nahanni Mineral and Energy Resource Assessment (MERA) undertaken from 2003 to 2007. The results have contributed to the process of determining the geographic boundaries of the proposed expansion of the Nahanni National Park Reserve. Four mineral potential maps were produced (one for each deposit type) using a knowledge-driven approach. A weighting scheme based on integrated mineral deposit and regional geological knowledge was derived for the various evidence maps for each deposit model using expert opinion. The four potential maps were then combined into a final potential map using a maximum operator. Plots showing the efficiency of the models (mineral potential maps) for predicting the known occurrences of the four deposit types show that partial data sets provide reasonable predictions of the remaining known mineral prospects, occurrences and deposits. Hydrocarbon potential from Nahanni MERA 1 was added to the final potential map to ensure that both mineral and energy potential data were incorporated into the park configuration modelling.

GIS-based Mineral Resource Assessment

GIS-based Mineral Resource Assessment

Assessing Afghanistan's mineral resources

Afghanistan has significant amounts of undiscovered nonfuel mineral resources, with copper and iron ore having the most potential for extraction, according to a new U.S. Geological Survey (USGS) assessment. The assessment, done cooperatively with the Afghanistan Geological Survey of the Afghanistan Ministry of Mines, also found indications of significant deposits of colored stones and gemstones (including emeralds, rubies, and sapphires), gold, mercury, sulfur, chromite, and other resources. “Mineral resource assessments provide government decision‐makers and potential private investors with objective, unbiased information on where undiscovered mineral resources may be located, what kinds of resources are likely to occur, and how much of each mineral commodity may exist in them,” said USGS director Mark Myers. The USGS, in cooperation with the Afghan government, released an oil and gas resources assessment in May 2007. For more information, visit the Web sites: http://afghanistan.cr.usgs.gov and http://www.bgs.ac.uk/afghanminerals/.

A Preliminary Quantitative Mineral Resource Assessment of Undiscovered Porphyry Copper Resources in the Andes Mountains of South America

A Preliminary Quantitative Mineral Resource Assessment of Undiscovered Porphyry Copper Resources in the Andes Mountains of South America

Quantitative Assessment of the Resource Potential of Porphyry Copper Systems in China

Using the method and principle of the “three-part” mode of mineral resource assessment, we have studied the geological setting, and temporal spatial distribution rule and models of the porphyry copper deposits in China. In our assessment we have also included 46 prospective areas. Based on the metal reserves database in 1999 and data from currently producing deposits, we have constructed a database of 984 deposits. We have studied grade-tonnage models according to the different types of mineralization, constructed a digital ore finding model, and developed quantitative assessment procedures for mineral resources. The probable resources for each prospective area have been calculated. This provides a reference database for evaluating the resource potential of porphyry copper systems in China.

Application of local singularity in prospecting potential oil/gas Targets

Abstract. Together with generalized self-similarity and the fractal spectrum, local singularity analysis has been introduced as one part of the new 3S principle and technique for mineral resource assessment based on multifractal modeling, which has been demonstrated to be useful for anomaly delineation. Local singularity is used in this paper to characterize the property of multifractal distribution patterns of geochemical indexes to delineate potential areas for oil/gas exploration using the advanced GeoDAS GIS technology. Geochemical data of four oil/gas indexes, consisting of acid-extracted methane (SC1), ethane (SC2), propane (SC3), and secondary carbonate (ΔC), from 9637 soil samples amassed within a large area of 11.2×104 km2 in the Songpan-Aba district, Sichuan Province, southwestern China, were analyzed. By eliminating the interference of geochemical oil/gas data with the method of media-modification and Kriging, the prospecting area defined by the local singularity model is better identified and the results show that the subareas with higher singularity exponents for the four oil/gas indexes are potential targets for oil/gas exploration. These areas in the shape of rings or half-rings are spatially associated with the location of the known producing drilling well in this area. The spatial relationship between the anomalies delineated by oil/gas geochemical data and distribution patterns of local singularity exponents is confirmed by using the stable isotope of δ13C.

Circum‐Arctic Map compilation

The eyes of the world are increasingly focused on the polar regions. Exploration and assessment of energy and mineral resources for the growing world economy are moving to high‐latitude frontier areas. The effects of climatic changes are particularly pronounced at these ends of the Earth and have already attracted worldwide attention and concern. Many recent articles related to the International Polar Year underscore the importance of even basic mapping of the Arctic and Antarctic.

Porphyry Copper Deposit Tract Definition – A Global Analysis Comparing Geologic Map Scales

Geologic maps are a fundamental data source used to define mineral-resource potential tracts for the first step of a mineral resource assessment. Further, it is generally believed that the scale of the geologic map is a critical consideration. Previously published research has demonstrated that the U.S. Geological Survey porphyry tracts identified for the United States, which are based on 1:500,000-scale geology and larger scale data and published at 1:1,000,000 scale, can be approximated using a more generalized 1:2,500,000-scale geologic map. Comparison of the USGS porphyry tracts for the United States with weights-of-evidence models made using a 1:10,000,000-scale geologic map, which was made for petroleum applications, and a 1:35,000,000-scale geologic map, which was created as context for the distribution of porphyry deposits, demonstrates that, again, the USGS US porphyry tracts identified are similar to tracts defined on features from these small scale maps. In fact, the results using the 1:35,000,000-scale map show a slightly higher correlation with the USGS US tract definition, probably because the conceptual context for this small-scale map is more appropriate for porphyry tract definition than either of the other maps. This finding demonstrates that geologic maps are conceptual maps. The map information shown in each map is selected and generalized for the map to display the concepts deemed important for the map maker’s purpose. Some geologic maps of small scale prove to be useful for regional mineral-resource tract definition, despite the decrease in spatial accuracy with decreasing scale. The utility of a particular geologic map for a particular application is critically dependent on the alignment of the intention of the map maker with the application.

Discussion of ‘Methodology to identify badly weathering limestone using geochemistry: case study on theLower Globigerina Limestone of the Maltese Islands’ byJ. Cassar & A.J. Vella Quarterly Journal of Engineering Geology and Hydrogeology , 36, 85–96

P.A. Gatt writes: The Authors offer an interesting perspective on the weathering of limestone dimension stone used for masonry in Malta, also studied by Fitzner et al . (1997) and Gatt (2007). They conclude that a single parameter, namely the difference in marginal non-carbonate content, can be used to predict the durability to weathering in the pelagic sediments of the Lower Member of the Globigerina Limestone Formation, even in freshly cut stone that does not present visual differences. A geochemical approach is used to distinguish between a problematic stone characterized by strong differential weathering with rapid loss of volume, locally known in Malta as ‘soll’ (Fig. 1), from a limestone that weathers more uniformly, known locally as ‘franka’, which is the preferred dimension stone for masonry buildings. The purpose of this discussion is to compare the stratigraphy sampled by the Authors with other works and to focus on the hypothesis linking non-carbonate content to weathering in the Globigerina Limestone Formation. The Authors describe the general stratigraphy as follows: ‘ the Islands and submerged platform are characterised by Mesozoic sediments ’. This is inconsistent with published works (e.g. Pedley 1978) that have always considered the limestone of the Maltese Islands (apart from very limited Quaternary sediments) to be exclusively of a mid- to Late Tertiary age. The limestone samples studied by the Authors are mainly derived from three cores with grid reference co-ordinates and depths that match those of three boreholes in south–central Malta found in the confidential Mineral Resource Assessment Report by Wardell Armstrong (1996). The locations of these boreholes are mapped by the Authors in their figure 2, although the location of borehole 2 should read borehole 3 (tar-Robba quarry). The Wardell Armstrong (1996) report has only recently become available, making possible comparisons with the paper by …

English

The traditional sequence and pace of events that occur following discovery and through mine permitting is increasingly unacceptable in light of global communications and heightened environmental and social sensitivity. Local and international NGOs can readily capitalize on corporate failures to be sufficiently environmentally and socially proactive. Eleventh-hour impact assessments are likely to be deemed inadequate and may cause significant financial losses. A flowchart has been developed to illustrate how geo- environmental and biotic ligand models (BLMs) might be used to promote timely, fiscally-responsible assessments of future environmental impacts. The approach parallels accepted methods of mineral resource assessment and mining property valuation.

Introduction: Great Basin tectonics and metallogeny

The Great Basin physiographic province in western North America chronicles a protracted tectonic history punctuated by events that pro-duced a wide range of structures, basins, magmas, and fl uids, leading to the formation of a diverse assortment of small to world-class metallic ore deposits for several important commodities. These ore deposits have been mined in several “boom-and-bust” cycles over the past 150 years. The Great Basin region is currently the world’s second leading producer of gold. It also contains large silver and base metal (Cu, Zn, Pb) deposits, a variety of other important metallic (Fe, Ni, Mo, W, Be, REE, Hg, PGE, Ga) and industrial mineral (diatomite, barite, perlite, kaolinite) resources, and signifi cant petroleum, geothermal energy, and groundwater resources. With the current high demand for metals in the United States and the increasing need for metals in developing coun-tries around the world, the Great Basin is likely to remain an important exploration and mining area for many years to come.Nearly all of the metallic ore deposits in the Great Basin formed in the Phanerozoic in a number of different environments, in response to tectonic events, at sites where both new and preexisting geologic features controlled hydro-thermal fl uid movement and chemistry. Most of these hydrothermal systems operated in the upper crust and were infl uenced by paleogeogra-phy and climate. Hence, the age and attributes of ore deposits in the Great Basin place important constraints on ancient geologic climatic envi-ronments. Subsequent burial/exhumation histo-ries controlled the preservation or modifi cation of ore deposits and determined their positions relative to the present ground surface. Conse-quently, information on a wide variety of top-ics is of great interest to geologists involved in exploration and mineral resource assessments in important metallogenic provinces such as this. Such knowledge also facilitates the develop-ment of improved models that relate deposit formation to specifi c environments and styles of tectonism that are applicable to other areas of the globe.This preface and the paper that follows it mark the beginning of a series of articles devoted to Great Basin tectonics and metallogeny. These papers will be published in the order in which they are accepted and will then be linked together to form a special volume. They are an outgrowth of a fi ve-year U.S. Geological Survey project (Hofstra and Wallace, 2006) that spon-sored sessions at the 2005 Geological Society of America Annual Meeting in Salt Lake City, Utah, titled “Great Basin Tectonics and Metal-logeny.” The meeting included presenters from the Survey, academia, and industry (

The “Three-Component” Digital Prospecting Method: A New Approach for Mineral Resource Quantitative Prediction and Assessment

Stimulated by the exceeding progress of information technology, the development of mineral exploration has entered a new period of digitization and quantification. The “three components” approach of mineral prediction is suggested as a new approach to the “digital mineral prospecting,” which is based on the geoanomaly analysis, directed by the research on the diversity of mineralization and on the spectrum of mineral deposits. Close combination of these three aspects of quantitative study makes a new starting point to the digital prospecting. In this paper, the basic theories of the “three components” approach of mineral prediction are discussed. In addition, based on the new achievements in the studies on the prediction and assessment of solid minerals and gas–oil resources, we have centered our discussion on the thought of analysis of geoanomaly evolution and on the “5P” method for approaching the target area in the “three components” approach of mineral prediction.

8-1: Fennoscandian shield–proterozoic VMS deposits

Mapping of mineral prospectivity and assessment of undiscovered mineral deposits both aim to delineate prospective ground for mineral exploration, but the latter is usually carried out exclusive of the former. We propose that the spatial distribution of known mineral deposits of the type sought is the key to link mapping of mineral prospectivity and assessment of undiscovered deposits. We demonstrate this proposition in regional-scale mapping of prospectivity for volcanogenic massive sulphides (VMS) deposits and estimation of undiscovered VMS endowment in the Skellefte district (Sweden). The results of analyses of the spatial distribution of known VMS deposits and their spatial associations with geological features are consistent with existing knowledge of geological controls on VMS mineralization in the district, and we used them to define spatial recognition criteria of regional-scale VMS prospectivity. Integration of layers of evidence representing spatial recognition criteria of VMS prospectivity via application of data-driven evidential belief functions results in a regional-scale map of prospective areas occupying 15% of the district and having fitting- and prediction-rates of 100%. We used the map of prospective areas and proxy measures for degrees of exploration based on the spatial distribution of known VMS deposits in one-level prediction of undiscovered mineral endowment. We obtained estimates of 709 Kt undiscovered Cu endowment, 3190 Kt undiscovered Zn endowment, 95 Mt undiscovered ore tonnage, and 48 undiscovered VMS deposits. These estimates are slightly (ca. 5% on average) lower than, and thus corroborated by, estimates obtained via radial-density fractal analysis of the spatial distribution of known VMS deposits. Therefore, mineral prospectivity mapping can be a part of mineral resource assessment if the spatial distribution of discovered deposits of the type sought is considered in both predictive modeling processes.

MRPM: three visual basic programs for mineral resource potential mapping

A traditional method for mineral resource potential mapping is to superimpose a number of indicator maps, and to combine geological information with or without the use of multivariate statistical models. More recently, GISs have become widely applied in mineral resource assessment and many statistical models for geological information synthesis have been proposed. GIS-based mineral resource potential mapping has facilitated modern mineral resource assessment. As a contribution to publicly available computer software for GIS-based mineral resource assessment, integrated three Visual Basic programs have been developed on MapInfo platform. The programs integrate map patterns using weights of evidence, applied general C-F, and evidence theory models, and generate posterior probability, combined certainty factor, and combined basic probability assignment maps, respectively. The software is demonstrated by a case study based on a real data set.