Geophysical and Geochemical Approaches to Evaluating Rare Earth Element (REE) Potential in the Southeastern U.S.

map of airborne radiometric data Airborne radiometric Thorium (Th) (Duvall et al., 2005) overlain with lanthanum (La) content of stream sediment samples (USGS, 2004) for the southeastern U.S. (Image by A. Shah, USGS) View large version of image (1.41 MB).

Rare earth element (REE) minerals housed in sedimentary environments are much easier to extract than those hosted in intrusions and thus provide a potentially important U.S. resource. While REE concentrations are typically small, they are often mixed with other mineral resources that are available in economic quantities. Various studies have indicated the presence of such resources in the southeastern U.S. in the form of placer, phosphoritic, and possibly residual (soil/clay) environments, but many questions remain how actual amounts vary geographically over this large area (Pirkle et al., 1989; Grosz and Schruben, 1994; Long et al., 2010; Cross and Lasseter, 2011; Foley, 2012). Geophysical data analyses provide a means of remotely sensing mineral concentrations of interest and mapping their probable spatial extent. When combined with geochemical and mineralogical ground-truth data, they form a powerful tool.

Project objectives are to develop geophysical, geochemical, and mineralogical methods for the detection and evaluation of REE mineral deposits for the purposes of evaluating probable extent in the southeastern U.S. Planned outcomes include determining best ways to combine datasets in a quantitative manner (leading to more rigorous calibration and usage of these tools), determining relations between geophysical and geochemical/mineralogic sample properties, and obtaining an increased understanding of the processes associated with genesis and evolution of these deposit types. Learn more about the project.