Temporal and spatial variability in dune reactivation across the Nebraska Sand Hills, USA

Abstract

The Nebraska Sand Hills is a stabilized dune field on the Great Plains of North America. Although it is well known that this dune field, like several others on the Great Plains, last experienced widespread activity during the Medieval Climatic Anomaly (MCA, ~AD 900–1300), spatial variation in the timing and nature of drought development is poorly constrained. To elucidate spatial trends in dune reactivation, samples potentially representing MCA activity across the Sand Hills were collected and dated using optically stimulated luminescence (OSL). Ages from the older part of the MCA were obtained from eolian sediments in the northwestern Sand Hills, while ages from later in the episode were obtained to the southeast, suggesting a geographic trend in the timing of revegetation of the dunes near the end of the drought. Revegetation likely occurred to the northwest initially as a result of renewed moisture availability from a rising water table in the interdunes, which serve as refugia for vegetation during times of drought. Vegetation then gradually spread to the southeastern Sand Hills. An additional spatial trend in ages is apparent in the chronology of linear dune mobilization across the Sand Hills. Linear dunes in the northwest are superimposed on megadunes and originated during the last reactivation, while linear dunes in the southeast are built around older cores of dunes and formed during several reactivations. Our geochronology reveals three episodes of eolian transport, including the MCA, in the formation of linear dunes in the southeast.

Chronology of dune development in the White River Badlands, northern Great Plains, USA

“…While the middle-to late-Holocene period 6 ka to 700 a was not preserved in WRB dunes crests sampled in this study, significant episodes of aeolian sedimentation were recorded elsewhere on the Great Plains at this time. NSH episodes of aeolian activity centered on 3.8 ka, 2.5 ka, and 670 a Mason et al, 2004;Miao et al, 2007b;Muhs et al, 1997;Schmeisser McKean et al, 2015;Stokes and Swinehart, 1997). Other dune fields on or adjacent to the Great Plains active at this time include the Ft. Morgan dunes, active at 4.9 ka (Clarke and Rendell, 2003); the Ferris dune fields, active from 4.3 ka to 4.0 ka (Stokes and Gaylord, 1993); the Casper dune fields, active between 1.0 ka and 400 a (Halfen et al, 2010); and the Wray dunes, active at 700 a .…”

“…1). Much of the aeolian research on the Great Plains has focused on the area's largest dune field, the Nebraska Sand Hills (NSH) (Ahlbrandt and Fryberger, 1980;Forman et al, 2005;Goble et al, 2004;Mason et al, 2004;Mason et al, 2011;Miao et al, 2007b;Muhs and Holliday, 1995;Schmeisser McKean et al, 2015;Sridhar et al, 2006), and the midcontinental, last glacial loess (Peoria Loess), which crops out widely on the Great Plains and Central Lowlands of North America Mason, 2001;Miao et al, 2007a;Muhs and Bettis, 2000;Muhs et al, 2008;Muhs et al, 2013;Muhs et al, 2018). Nonetheless, chronologies of aeolian activity in dune fields on the periphery of the NSH and the margins of the Great Plains are necessary to demonstrate the timing and extent of drought in the region (Halfen and Johnson, 2013;Halfen et al, 2016;Hanson et al, 2010).…”

“…et al, 2009a;Mann et al, 2009;Sridhar et al, 2006). During the MCA, periods of drought significantly longer than those of the modern era (megadroughts) (Feng et al, 2008;Woodhouse and Overpeck, 1998), caused reactivation of dunes in the NSH and other dune fields on the Great Plains (Forman et al, 2005;Forman et al, 2001;Goble et al, 2004;Hanson et al, 2010;Schmeisser McKean et al, 2015;Schmeisser et al, 2010). Droughts coincident with the LIA also appear to have reactivated dunes, especially in the western and southern sections of the Great Plains (Clarke and Rendell, 2003;Forman et al, 2008;Forman et al, 2005;Halfen et al, 2010).…”

The structure of Holocene climate change in mid-latitude North America

“…Because dust flux can relate to aridity in a nonlinear fashion (e.g., potential dust-source areas may change exponentially in extent during drought) and because the data are not normally distributed, we log transformed the XRD data for all plots and analyses. Despite potential complexities, such as the role of winds and changing sources of fine particulates (Mason et al, 2003;McKean et al, 2015;Muhs et al, 2008), we use the records because they provide an opportunity to evaluate the fidelity of the signals in replicated records from the same area. They also provide detailed information about the relative sequence of hydroclimate changes in a sub-region without the type of quantitative lake level records used elsewhere.…”

Evaluation of simple geochemical indicators of aeolian sand provenance: Late Quaternary dune fields of North America revisited

“…3). Although most dunes in the Great Plains and many in the Basin and Range deserts are presently stabilized by vegetation, there is ample evidence that sand in most dune fields has been active within the late Holocene (Ahlbrandt et al, 1983;Swinehart, 1990;Stokes and Gaylord, 1993;Madole, 1995;Loope et al, 1995;Arbogast, 1996;Clarke et al, 1996;Muhs et al, 1996Muhs et al, , 1997aMuhs et al, , 1997bStokes and Swinehart, 1997;Wolfe et al, 2000;Holliday, 2001;Lancaster and Tchakerian, 2003;Goble et al, 2004;Mason et al, 2004;Forman et al, 2005;Goble, 2006, 2015;Miao et al, 2007;Wolfe and Hugenholtz, 2009;Schmeisser et al, 2010;Rich and Stokes, 2011;Halfen et al, 2012Halfen et al, , 2016Schmeisser McKean et al, 2015).…”