Locatable Mineral Assessment Tracts for the U.S. Geological Survey Sagebrush Mineral-Resource Assessment Project

The polygon (vector) feature class represents locatable mineral resource assessment tracts (tracts of land) associated with the Department of the Interior (DOI) Sagebrush Focal Areas (SFAs) in Montana, Wyoming and Utah, central Idaho, and the Oregon-Nevada-Idaho border area. The mineral-resources tracts are geographic areas that were assessed by the USGS and were determined to be geologically favorable for a deposit type of interest to a depth of 1 kilometer. Qualitative assessment methods outlined by the Bureau of Land Management (BLM) were used to develop tract boundaries and to assign a level of mineral-resource potential and certainty to each tract. The general process included (1) identifying possible mineral deposit types for locatable commodities specified by BLM for each focal area, (2) outlining those areas that potentially contained mineral deposits based on geology, mineral occurrences, geophysics, soil and stream-sediment geochemistry, alteration mineral assemblages inferred from satellite imagery, BLM claims and permit data, mineral-exploration activity, and existing mineral-resource assessment data, and (3) evaluating the level of mineral-resource potential and level of certainty associated with the outlined areas using BLM assessment categories. A full description of the assessment is provided in the accompanying report (Day and others, 2016). SFAs, identified by agencies of the DOI, are high-quality sagebrush habitat areas supporting high densities of breeding greater sage-grouse (Centrocercus urophasianus). SFAs are within priority habitat areas or areas where land-use measures are intended to minimize or avoid habitat disturbance. Seven SFAs are within the USGS Sagebrush Mineral-Resource Assessment Project study area. They include the Bear River Watershed, North-Central Idaho, North-Central Montana, Southeastern Oregon and North-Central Nevada, Sheldon-Hart Mountain National Wildlife Refuge Complex, Southern Idaho and Northern Nevada, and Southwestern and South-Central Wyoming SFAs, as well as additional areas in Nevada (termed the “Nevada additions”) proposed by the State of Nevada. Landscape-scale conservation efforts by the BLM, U.S. Fish and Wildlife Service (FWS), the U.S. Forest Service (USFS), State agencies, private land owners, and other partners are striving to conserve the breeding sagebrush habitat for the greater sage-grouse across these areas. Accompanying report (Chapter A): Day, W.C., Hammarstrom, J.M., Zientek, M.L., and Frost, T.P., eds., 2016, Overview with methods and procedures of the U.S. Geological Survey mineral-resource assessment of the Sagebrush Focal Areas of Idaho, Montana, Nevada, Oregon, Utah, and Wyoming: U.S. Geological Survey Scientific Investigations Report 2016–5089, 211 p., http://dx.doi.org/10.3133/sir20165089.