Aeolian sand depositional records from western Nebraska: landscape response to droughts in the past 1500 years

Abstract

The Great Plains is dominated by presently stabilized dune fields that are indicators of extreme drought in the late Holocene. This study focused on deciphering the timing of reactivation of dunes in western Nebraska. Stratigraphy adjacent to dune-dammed lakes reveals aeolian sand separated by palaeosols, indicating mobilization of aeolian sand followed by landscape stability. The chronology of aeolian-sand depositional events is constrained using the luminescence-based, single aliquot regeneration method, providing resolution to relate dune movement to tree-ring and palaeolimnologic records of drought. There are at least a six aeolian depositional events in the past 1500 years, with apparent mean ages of 1390+130, 670 +70, 470 +40, 240 +40, 140 +20 and 70+10 yr. All study sites show evidence for aeolian accumulation in the twentieth century, potentially reflecting the 1930s drought. Significant aeolian activity is coincident with the tree-ring-identified sixteenth-century megadrought, indicating widespread landscape impacts.

A regional-scale climate reconstruction of the last 4000 years from lakes in the Nebraska Sand Hills, USA

“…Holocene paleoclimatic evidence from the Nebraska Sand Hills region is predominantly derived from paleosols and eolian sediments (Stokes and Swinehart, 1997;Goble et al, 2004;Miao et al, 2007;Forman et al, 2005), as well as from a limited number of studies of wetland and marsh systems (Mason et al 1997;Nicholson and Swinehart, 2005). Optically stimulated luminescence (OSL) dating of sand and loess deposits, in conjunction with radiocarbon dates from paleosols interspersed between dune deposits, provides evidence of the timing of droughts that destabilized the dune fields in the past.…”

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

“…OSL dating of eolian sediments in combination with radiocarbon dating of paleosols by Goble et al (2004) provided additional evidence for reactivation of dune sediments during the MCA. Forman et al (2005) found evidence from OSL dating for six reactivations during the past 1500 years at two sites in the Nebraska Sand Hills, including one potentially correlative with 16th century drought identified in other parts of the western United States. Miao et al (2007) used OSL to date eolian sediments and loess sediments from numerous sites in the central Great Plains, including the Nebraska Sand Hills, and found three major peaks of eolian activity during the last 4000 years, centered at 3.8, 2.5, and between ~1.0 and 0.7 ka.…”

“…Extensive reactivation of the dune field has occurred three times in the last 4000 years, centered around 3.8, 2.5, and between ~1.0 and 0.7 ka during the MCA (Miao et al, 2007). Partial reactivations of the dunes (involving increased areas of bare sand and partial movement) have occurred since the MCA, including the 1930s Dust Bowl and other prehistoric episodes (Forman et al, 2005), but none have led to such extensive reactivation.…”

“…Extensive OSL dating of dune sediments in the Sand Hills has contributed toward a better understanding of Holocene periods of dune movement (Forman et al, 2005;Goble et al, 2004;Mason et al, 2004;Miao et al, 2007). Mason et al (2004) applied OSL dating to several upland and interdune sites across a large area of the Sand Hills and recognized a short period of dune movement from about 1000-700 years ago.…”

“…The dunes in the Nebraska Sand Hills have been the focus of many recent studies focused on determining the timing of dune reactivations (Forman et al, 2005;Goble et al, 2004;Mason et al, 2004Mason et al, , 2011Miao et al, 2007;Muhs et al, 1997;Stokes and Swinehart, 1997;Stokes et al, 1999). Early researchers considered the Sand Hills to be primarily Pleistocene relicts, with little to no movement of the dunes during the Holocene (Smith, 1965).…”