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GMEG - Geology, Minerals, Energy, & Geophysics Science Center

Mineral resource assessment methods—An ore systems approach

 

Issue: The Geological Survey was established by the Organic Act of March 3, 1879, which provided for "the classification of the public lands and examination of the geological structure, mineral resources, and products of the national domain." To accomplish its mission, the Geological Survey conducts and sponsors research that includes assessing energy and mineral resources. For the last 30 years, USGS assessments have used the 3-part form of assessment to produce mineral potential maps showing where undiscovered resources may be located and to probabilistically estimate how much material may be present. In the same time period, tremendous advances have been made in our understanding of ore forming process and the use of spatial analysis to map mineral prospectivity. In November 2011, the USGS sponsored the Quantitative Mineral Resource Assessment Forum to discuss future directions in mineral resource assessment within the USGS. In the course of discussion, several points were made:

  • USGS assessment methods should be based on best available science
  • Future mineral resource assessment methods should explicitly integrate genetic concepts on ore-systems into assessment protocols
  • Spatial analysis methods should be used to map variations in mineral prospectivity within thearea of interest. At the same time, the assessment methods should be consistent, minimize bias, and express uncertainty

The method should also be transparent so that the results are reproducible.

Objectives: The objective of this project is to publish a report that outlines how an ore systems approach can be integrated into USGS mineral resource assessments. The report should address:

  1. principles underlying resource assessment
  2. objectives of resource assessment
  3. the need to explicitly include theories of ore genesis in resource assessment
  4. the ore systems paradigm
  5. area selection using the ore systems concept
  6. strategies for making probabilistic estimates of mineral endowment in study areas
  7. data requirements
  8. integration with other kinds of assessments

Relevance: We should be able to take our understanding of ore genesis and identify field-based criteria that are needed to define the permissive geologic setting for undiscovered ore deposits. Descriptive models for ore deposits summarize the intrinsic properties of a mineral deposit type but they do not explicitly identify the criteria for tract delineation. This project will try to identify the essential components of ore systems and present ideas on how they can be used in the development of deposit models and resource assessment protocols. We expect these discussions to identify gaps in our knowledge that will suggest directions for future mineral deposit research.

Project staff

Project Leader: Michael Zientek - (509) 368-3105 - mzientek@usgs.gov

Ed Du Bray - (303) 236-5591 - edubray@usgs.gov

Poul Emsbo - (303) 236-1113 - pemsbo@usgs.gov

Mark Gettings - (520) 670-5507 - mgetting@usgs.gov

Al Hofstra - (303) 236-5530 - ahofstra@usgs.gov

Greg Lee - (303) 236-2491 - glee@usgs.gov

Mark Mihalasky - (509) 368-3118 - mjm@usgs.gov

Lukas Zurcher - (303) 236-0548 - lzurcher@usgs.gov

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