Abstract
AbstractInland dune fields have recently emerged as a source of data for reconstructing paleoenvironments and climate in the western Great Lakes region of North America during the Pleistocene-Holocene transition. We employ optically stimulated luminescence (OSL) methods, radiocarbon ages, soils, and landform relationships to determine the age of inland dunes in Ottawa County, Michigan. These dunes rest on the abandoned bed of Glacial Lake Chicago, which is thought to have been exposed after ~13.6 ka. OSL analyses from two inland dunes yield ages ranging from 13.3±1.1 to 11.6±0.9 ka (uncertainty=2σ). Fine sand in the parabolic dunes suggests deflation of exposed glaciolacustrine nearshore sand by northwesterly and westerly winds. These new data add to a growing number of studies that demonstrate widespread eolian activity in the western Great Lakes region during the Pleistocene-Holocene transition. OSL ages from dune fields in the western Great Lakes indicate peak eolian activity and dune stabilization occurred during or following the Younger Dryas and Preboreal events. Northwesterly and westerly winds suggest the limited effect of hypothesized easterly anticyclonic winds during the Pleistocene-Holocene transition. Rapidly changing climate and newly deglaciated surfaces provided an ideal environment for dune formation.
Highlights
Late Pleistocene and Holocene eolian dunes in the western Great Lakes region of North America (Fig. 1A) are increasingly being used as a source of evidence for paleolake levels, glaciofluvial sedimentation events, climate changes, and past atmospheric circulation patterns
Finding suitable optically stimulated luminescence (OSL) sampling sites was facilitated by use of a digital elevation model (DEM) derived from LIDAR data collected by Ottawa County, Michigan, in 2004
The dune sampled at Hemlock Crossing Park (Fig. 3B) is part of a compound parabolic dune with arms oriented to the northwest (~340°)
Summary
Late Pleistocene and Holocene eolian dunes in the western Great Lakes region of North America (Fig. 1A) are increasingly being used as a source of evidence for paleolake levels, glaciofluvial sedimentation events, climate changes, and past atmospheric circulation patterns. Coastal spits and dunes have been employed to reconstruct paleowind patterns associated with a hypothesized anticyclone, which may have persisted over a retreating Laurentide Ice Sheet (Krist and Schaetzl, 2001; Kilibarda and Blockland, 2011; Vader et al, 2012). Most of these studies use optically stimulated luminescence (OSL) to estimate the age of eolian sediments as this method is well suited to quartz-dominated loess and dune sand. Coastal dunes are large parabolic dunes up to 50 m in relief, and sometimes perched up to 100 m above the current lake
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