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U.S. Geological Survey
Open-File Report 01-291

Mineral Potential Modelling of Gold and Silver Mineralization in the Nevada Great Basin—A GIS-Based Analysis Using
Weights of Evidence

By

Mark J. Mihalasky

The distribution of 2,690 gold-silver-bearing occurrences in the Nevada Great Basin was examined in terms of spatial association with various geological phenomena. Analysis of these relationships, using GIS and weights of evidence modelling techniques, has predicted areas of high mineral potential where little or no mining activity exists. Mineral potential maps for sedimentary ("disseminated") and volcanic ("epithermal") rock-hosted gold-silver mineralization revealed two distinct patterns that highlight two sets of crustal-scale geologic features that likely control the regional distribution of these deposit types.

The weights of evidence method is a probability-based technique for mapping mineral potential using the spatial distribution of known mineral occurrences. Mineral potential maps predicting the distribution of gold-silver-bearing occurrences were generated from structural, geochemical, geomagnetic, gravimetric, lithologic, and lithotectonic-related deposit-indicator factors. The maps successfully predicted nearly 70% of the total number of known occurrences, including ~83% of sedimentary and ~60% of volcanic rock-hosted types. Sedimentary and volcanic rockhosted mineral potential maps showed high spatial correlation (an area cross-tabulation agreement of 85% and 73%, respectively) with expert-delineated mineral permissive tracts. In blind tests, the sedimentary and volcanic rock-hosted mineral potential maps predicted 10 out of 12 and 5 out of 5 occurrences, respectively. The key mineral predictor factors, in order of importance, were determined to be: geology (including lithology, structure, and lithotectonic terrane), geochemistry (indication of alteration), and geophysics.

Download the entire report (approximately 200 pages long) as a PDF document (53 MB)

Download Appendix B as a zip file (3 KB)

Download a gif animation of time-slice maps of Cenozoic igneous rocks in Nevada. (38 KB)

For questions about the content of this report, contact Mark Mihalasky

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URL of this page: http://pubs.usgs.gov/of/2001/of01-291/
Maintained by: Michael Diggles
Created: October 10, 2001
Last modified: July 5, 2005 (mfd)

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