The USGS Earth Mapping Resource Initiative (EMRI) is funding the South Carolina Geological Survey to evaluate the potential for Ti-Zr-REE Placer deposits within the South Carolina Upper Atlantic Coastal Plain (UACP). The Aiken 100k quadrangle is located along the Fall Line, the geomorphic boundary between the UACP and the Piedmont. The UACP stratigraphy consists of Upper Cretaceous to Quaternary sediments (i.e. sinks) deposited in fluvial-deltaic, marginal marine, and aeolian environments. West of the Fall Line, the Piedmont contains greenschist to amphibolite facies metamorphic and plutonic igneous rocks (i.e. sources). Historical exploration in the area and new high-resolution geophysical surveys showing prominent radiometric anomalies (eTh, eU) representing REE-bearing minerals require new mapping and geochemical sampling to better understand formation of these economically important deposits.

Geochemical sampling is being used to characterize the stratigraphy and to target areas having high radiometric anomalies. Initial screening was done with a portable X-Ray Fluorescence analyzer (pXRF). Statistical analysis of pXRF data is identifying geochemical differences within and outside of radiometric eTh highs. Al was used as an indicator for clay content, Th for REE content, Ti for ilmenite and rutile, Y for xenotime, and Zr for zircon. To determine if REEs were likely to be clay-hosted, a linear regression was calculated comparing clay content (Al) and Th (REE). A positive correlation was found in samples from areas lacking radiometric eTh highs, whereas no such correlation existed in samples within eTh highs. This correlation suggests that REEs within these high Th anomalies are unlikely to be clay-hosted. To determine whether radiometric anomalies contained an increased concentration of REE-bearing minerals, statistical A/B testing compared Ti, Y, and Zr in samples taken from within and outside of these anomalies. Data was then bootstrapped to more accurately estimate the distribution of sampled concentrations. Samples from within these anomalies also contained moderately higher concentrations of Y and significantly higher Zr than those outside of anomalies, potentially indicating increased presence of the REE bearing minerals xenotime and zircon. Visual analysis of samples has confirmed presence of these REE-bearing minerals. Further grain size analysis, bulk geochemistry, and high-resolution minerology will continue to test this hypothesis.