LANDSCAPE GEOCHEMISTRY OF THE SUPERIOR UPLAND PROVINCE, USA
Geochemical data were utilized from the National Uranium Resource Evaluation (NURE) program, available online through the National Geochemical Survey database at http://tin.er.usgs.gov. The Superior Upland Province contains approximately 6,000 samples, which were analyzed using Inductively Coupled Plasma-40 (ICP40) with total digestion. Univariant, bivariate, and multivariate statistical analyses were performed on ICP40 data. Results are given in element concentrations, smoothed single element maps, factor maps, and outlier point maps for significant elements, using GIS softwares ArcView and ArcCatalog. These maps are useful for indentifying local background concentrations, showing the distribution of anomalous element concentrations, and identifying outliers for investigation. Outliers include natural enrichment, mining areas, and other anthropogenic sources. An example showing anomalous values for Ni, Co, Cu, Mg, As, and Eu outliers is in Two Harbors, MN. Geochemical data were viewed simultaneously with layers such as geologic maps, locations of mines and industry, land use, physiography, and other relevant base maps (ie glacial landforms). 29 single element maps were studied, and 10 factors were extracted from ICP40 data. Element maps were subdivided into regions and analyzed according to bivariant analysis, visual comparison, and correlation coefficients from factor analysis. The 1st factor shows a robust mafic association (Ni, Co, Fe, Zn, V, Sc, Mn, Cu, & Al), the 2nd factor an alkali feldspar association (Na, Sr, Ba, K, Al, & Ga), the 3rd factor a LREE association (Ce, La, Y + Th), and the 4th factor a limestone association (Ca, Mg).
Regional geochemical mapping of the Superior Upland Province effectively shows background element concentrations, geochemical associations, mineralization, and environmental impact. The results of this study can be downloaded from http://cybershare.utep.edu