2004 Denver Annual Meeting (November 7–10, 2004)

Paper No. 13
Presentation Time: 5:00 PM


MAHAN, Shannon, US Geol Survey, Box 25046 Federal Center, Denver, CO 80225, RAWLING, J. Elmo, III, Geography/Geology, Univ. of Wisconsin, 1 University Plaza, Platteville, WI 53818, LILLESVE, Cayce, U.S. Geol Survey, Box 25046 MS974, Denver Federal Center, Denver, CO 80225 and SWINEHART, Jim, Dept. of Geosciences, Univ of Lincoln-Nebraska, 102 NH, UNL, Lincoln, NE 68588-0517, smahan@usgs.gov

Many Quaternary features within the White River Badlands of South Dakota are being systematically evaluated and dated for depositional history and landscape development using luminescence dating. These features include eolian landforms such as parabolic dunes and cliff-top deposits containing Holocene soils. Fluvial deposits such as lacustrine rhythmic sediments and colluvium are also included in the study. From 2000 to 2004 approximately twelve samples were collected from Cuny Table, Kuderna Table, Sheep Mountain Table, Hay Butte and the parabolic dunes near 185th Avenue. The 185th Avenue sample site was previously dated using Blue-light OSL (Blue OSL) on fine sand-size quartz grains by another luminescence laboratory. This site was re-sampled for use as a corroborative marker in this study. Radiocarbon ages that were obtained in earlier investigations on total organic matter in soils are also being used in conjunction with luminescence ages.

Varying luminescence techniques have formed a large body for “proof of concept” data on depositional history and process for these Holocene and Pleistocene sediments. Traditional thermoluminescence (TL) as well as Infrared Stimulated Luminescence (IRSL) were applied to silt-size feldspar grains from these deposits. For fine sand-size quartz grains, we used Blue OSL. For TL and IRSL, we generated ages using multiple-aliquot additive dose techniques, with some samples being run using a partial bleach technique. For Blue OSL, we ran samples using the single-aliquot regenerative technique. Generally, the dominant grain size in the deposit sampled was used for luminescence dating purposes, although occasionally the dominant size was greater than 180 microns and was thus ignored. The Blue-OSL and TL recorded older ages than the IRSL. Local stratigraphic relationships suggest that most mesa tops and dune formations were late Pleistocene or early Holocene. The oldest sample from Sheep Mountain Table was saturated with respect to luminescence and was older than 170,000 years, indicating late Pleistocene depositional processes. These samples aid in understanding the long-term development of the White River Badlands.