A SYNTHESIS OF HOLOCENE CLIMATE PROXY RECORDS, NORTHERN AND CENTRAL GREAT PLAINS, USA

This presentation puts the results of our dune studies on the aeolian deposits in the White River Badlands (WRB) in the context of other climate proxy and historic climate records of the Great Plains region. The stabilized dune fields studied exist as reworked sand sheets on the tops of tables in our field area south of Badlands National Park, and north of the White River. On the tables, Quaternary deposits lie unconformably on the Miocene Sharps Formation or the Oligocene Brule Formation. Above the unconformity are terrace deposits of reworked Tertiary strata, followed by the Red Dog Loess, aeolian sand, and most recently aeolian cliff-top deposits. The aeolian sand deposit on the tables ranges in thickness from entirely absent to 60m. The variable thickness is due to the reworking of the sand sheet, in the form of blowouts and dune formation.

Our recent work in the tabletop dune fields surrounding the White River Badlands has revealed periods of sedimentation throughout the Holocene. Samples were taken from stabilized dunes for optically stimulated luminescence (OSL) dating. The data obtained show periods of sedimentation during the Late Pleistocene through middle Holocene, ending around 6000 a, as well as activity beginning around 600 a and ending approximately 250 a, during the Little Ice Age. To place our data into context, this presentation summarizes previous works on dune mobilization, loess deposition, channel incision, lacustrine sediments, and tree ring records from various investigators studying the Great Plains. Aeolian activity is one of the most widely studied climate proxies in the Great Plains. Multiple dune studies have shown periods of sedimentation throughout the late Pleistocene to middle Holocene, ending around 6000 a in accordance with our data. The Little Ice Age is also recorded through dune mobilization records, especially in those of the Nebraska Sand Hills. Records of this recent event are in agreement across multiple localities, indicating that the reactivations may have been caused by regional climatic shifts.

Through a better understanding of Holocene paleoclimatic trends in the region, we will be able to further understand landscape response to climatic perturbations.