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Uncertainty and Risk Analysis in Mineral Resources Project Tasks

Task 1: Sensitivity analysis of the sources of uncertainty and risk

This task determines the magnitude and uncertainty of the factors that affect the net present value of mineral resources and identify those that are controllable. A sensitivity analysis system that captures the fundamental assumptions and various kinds of data input of quantitative assessments and exploration is developed and tested. Successful analysis and documentation of the major sources of uncertainty and risk will allow efficient allocation of time and money in subsequent project and program research.

Task 2: Risk reduction methods for covered resource areas

This task looks into finding ways to objectively predict resources remotely through cover. This will be accomplished by developing and testing a system that can predict geologic settings related to deposit types under cover based on geophysics and extrapolated geology. This work will rely on multivariate methods and probabilistic neural networks to estimate probabilities of different geologic settings associated with different deposit types.

This task will also included analysis of past exploration under cover, in light of current knowledge and methods, to develop a risk management strategy suitable for resource assessment and exploration. Task members will analyze past exploration under cover through mostly unpublished sources available to the public through various exploration archives, including that of the Arizona Department of Mines and Mineral Resources (Phoenix), the USGS (Spokane, Washington), and the American Heritage Center (Laramie, Wyoming). Recent research on porphyry copper genesis and Arizona geology will be reviewed as part of the reevaluation of past exploration.

Task 3: Risk reduction methods in assessments and exploration

The focus of this task will be on addressable sources of risk reduction methods in assessments and exploration. For example, if discriminating between two specific deposit types is found to have a major affect on assessment errors, then research might be focused on ways to better discriminate the two types in assessments or exploration.

Task 4: Characterizing risks of adverse effects of mining

Conceptual modeling and statistical analysis of the relations among the factors that may localize MethHg , Hg, and MethHg in animals will be preformed, in cooperation with EPA. The goal is to develop a framework to assist managers, regulators, and other stakeholders decide whether offsets can cost-effectively meet the Hg Total Maximum Daily Load (TMDL) requirements in the Sacramento River Watershed. The foundations for this project have been: (a) A probabilistic approach explicitly incorporating scientific uncertainty, cost information, and value judgments; and (b) A quantitative framework capturing uncertainty is useful in testing the feasibility of offsets for mercury.

Task 5: Mineral deposit model updates

This task will test existing mineral deposit models and to construct new models where applicable in support of quantitative mineral resource assessments.

Preliminary work suggests that a major source of uncertainty is tonnage--a source that can be predicted to some extent by deposit type.

To reduce uncertainty in grades, tonnages and delineation of zinc-bearing deposits, new consistent models of the major types need to be constructed. Build and test new deposit models for sediment-hosted zinc-lead, polymetallic replacement, and volcanic-hosted massive sulfide types of deposits.

In order to reduce uncertainty of grades and tonnages and delineation risks of gold and silver-bearing deposits, develop new geologic models on

• epithermal qtz-alunite-kaolinite-(pyrophyllite) precious and basemetal deposits
• porphyry copper deposits
• polymetallic vein and replacement base- and precious-metal deposits.

Prepare for publication a set of revised descriptive and grade and tonnage models.

The following work is designed to reduce the spatial uncertainty of porphyry copper deposits in Iran.

Revision to descriptive and grade and tonnage models for Au-Ag-Te mineralization associated with alkaline rocks. Revisions will be made to both the descriptive model and grade and tonnage model in a parallel fashion.

The following work is designed to reduce uncertainty in classifying and delineating PGE deposit types and provide some grade and tonnage models.

Compile a tectonic map of geologic, tectonic, deposit occurrence, and other data for the Uremieh-Dokhta Magmatic arc (Miocene) in Iran at 1,000,000 scale. Compile similar data on the same tectonic trend of the same age (and earlier ages) to the northeast in Georgia, Armenia, and eastern Turkey. Construct a map showing the relation between the fault duplexes and volcanic and plutonic rocks in the Uremieh-Dokhta Magmatic arc and the location of the porphyry copper deposits that occur in it. Associate the alteration as identified from processing Aster Satellite imagery with the deposits and the fault duplexes. Identify the possible areas of undiscovered deposits. Using similar maps and analysis connect the Uremieh-Dokhta Magmatic arc and its deposits to those in Armenia and Georgia and determine the association with the two sets of older porphyry copper deposits in the Armenia-Georgia and the deposits in eastern Turkey region.

Develop descriptive models for several Ni and PGE deposit types.

Develop grade-tonnage models for selected Ni-Cu-PGE deposit types. Participate in IGCP Project 479 sponsored workshop associated with the 10th International Platinum Symposium in Finland.

Task 6: Improvements in MARK 3 simulator

The original version of the MARK3 simulator has been heavily modified to produce a program called EMINERS. This program now includes the ability to apply economic filters to the calculations. The goal of this task is to continue development of the EMINERS program and to test the procedures and models that are now in place. The objective of this task is to continue development of the EMINERS program and to test the procedures and models that are now in place.

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