DEVELOPMENT OF GEOENVIRONMENTAL MODELS FOR MINERAL DEPOSITS BY THE USGS

The USGS Mineral Resources Program is currently developing geoenvironmental models (GEMs) for several mineral deposit types. These models are earth-science based descriptions of the environmental characteristics of mineral deposits. These models are intended to improve the ability to predict chemical effects of specific mineral deposit types in various weathering environments. At the present stage of development, GEMs are qualitative, descriptive, and incorporate such variables as geology, climate, hydrology, important suites of elements observed in surface and ground waters, and transport mechanisms and biological receptors for those elements. Earlier efforts to develop GEMs followed the framework of mineral resource models developed at USGS, with the intention of adding quantitative, predictive environmental models for each deposit type. While quantitative environmental models remain a goal of this research effort, our current focus is on complete mineralized systems within individual watersheds or groups of adjacent watersheds. This shift in emphasis recognizes that multiple deposit types may occur in a single watershed and that all may contribute to the chemistry of streams or ground water. Our hope is that GEM will have many users, including industry, multiple levels of government, and the public. Possible applications of GEMs include: identifying elements of interest or concern in anticipation of new mining activities; focusing remediation/mitigation efforts on those elements most likely to be of concern; aiding the design of mining/remediation/mitigation strategies; determining pre-mining baseline concentrations in areas affected by historic mining; establishing pre-mining baseline before new mine development; determining the potential environmental "footprint" and impact of new and historical mining activities; and geochemical exploration applications. The research projects currently underway at USGS address all these topics. As GEMs are now taking shape, we solicit additional suggestions and input from interested groups and potential future users.