DUNE SYSTEMS OF THE CENTRAL AND SOUTHERN GREAT PLAINS, USA

An often windy landscape with few major topographic features, poorly-consolidated fine-grained geology, and limited and variable precipitation has endowed the Central and Southern Great Plains with the ideal environment for aeolian entrainment and dunal formation. Dune activity results as sediment is available and transportable and wind velocities are of sufficient magnitude and duration (and perhaps gusty). Subsequent reactivation, which is often climatically forced, occurs when sediment again becomes transportable under a given wind regime. Our objective is that of reviewing existing studies and reporting yet unpublished luminescence data and LiDAR-based mapping from within a region extending from the North Platte River (excluding the Nebraska Sand Hills) south through western Kansas, Panhandle Oklahoma, northern and western Texas and eastern New Mexico. Most dune fields of the study region, with the exception of those in western Texas and adjacent southwestern New Mexico, are associated geographically with and in some cases geochemically-linked to one or more fluvial systems (e.g., the Arkansas, Cimarron). Previous reviews by Halfen and Johnson (2013; comparison of activation chronologies) and Halfen et al. (2016; sediment supply and other non-climate factors) have focused on dunes fields proper for the obvious reasons of ubiquity and trademark expression. A comprehensive consideration of dune systems for the Central and Southern Great Plains should consider also those lesser known dunes with characteristic singular occurrences, i.e., the lunettes, or crescentic dunes associated with playa basins (Kansas through to Texas into New Mexico), and the parna dunes of the Oklahoma Panhandle. Although playa basins number in the tens of thousands regionally, the number of lunettes is only in the hundreds, but these are notable features due to their unique expression on the landscape. Created by late-Pleistocene northwest winds, lunettes typically occupy the south-southwest side of the playa basins, and, due to climate fluctuations, stacked paleosols are characteristic. Parna dunes, somewhat elongated dunes appearing in low-density “swarms” and comprised of sand-sized aggregates of silt and clay particles, stabilized (formed?) about 25-21 ka.