SAND PROVENANCE ACROSS THE WHITE RIVER BADLANDS TOWARD THE NEBRASKA SAND HILLS

Previous investigators found systematic changes in mineralogical and textural maturity with downwind distance in the Nebraska Sand Hills (NSH), suggesting dominant transport from NW to SE. In addition, these investigators suggested that Eocene and Oligocene age strata of the White River Group in the White River Badlands (WRB) of southwestern South Dakota are a possible source of sand in the NSH. This study intends to embrace earlier inquiry regarding provenance, predicting that dunes located in the WRB downwind of the White River Group source rock contain sediment with a maturation signal intermediate between the source rocks and the NSH sand. Our investigation also extends previous works with geochemical data collected through sedimentologic characterization of sand and silt from the WRB alluvium, and dune fields south of Badlands National Park. Samples were collected from terraces and floodplains of the Cheyenne and White Rivers, and their tributaries, together with sand samples from parabolic dunes from tables (mesas) north of the White River in the WRB. These samples were analyzed using laser-induced breakdown spectroscopy (LIBS) to identify major element compositions. The hypothesis to be tested is that if White River Group sediment is the source for Nebraska Sand Hills, then major element composition should reflect sand maturation with transport, involving noted destruction of feldspars and other less resistant minerals. Preliminary results on geochemical analyses of sediments will be presented.