Geochronology and Depositional History of the Sandy Springs Aeolian Landscape in the Unglaciated Upper Ohio River Valley, United States

Matthew P Purtill,Steven L Forman,J Steven Kite

doi:10.3389/feart.2019.00322

Matthew P Purtill, Steven L Forman + Show 1 more

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https://doi.org/10.3389/feart.2019.00322

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Abstract

This study reports on the geochronology and depositional history of aeolian landforms and sediments in the unglaciated upper Ohio Valley at the Sandy Springs site. The distribution of aeolian sediments at Sandy Springs is influenced by several past factors including local wind fetch potential, sediment availability, and underlying alluvial topography. Aeolian landforms and sediments include complex, linear, barchan-like, and climbing dunes; an interdune sand sheet; and sandy loess that blankets high valley surfaces. At Sandy Springs, aeolian dune sands and sandy loess are restricted to intermediate (S2) and higher (S3) geomorphic surfaces. Eight optically stimulated luminescence age estimates constrain the initiation of aeolian processes on the S2 surface to sometime after 17 ka and episodic deposition on the S2 and S3 surfaces between 11 and 1.4 ka. Sandy loess deposition at ca. 8.2 ka on the S3 surface may reflect hydrologic variability and cooling, associated with the final pulse of meltwater into the North Atlantic from the Laurentide Ice Sheet. Dune reactivation and erosion at ca. 4.5 ka on the S2 surface indicate enhanced sediment availability possibly associated with drought conditions. These results illustrate that the deciphering the coupled fluvial-aeolian records in this catchment of the Ohio River provides new insight into the nature of changing surface processes against the backdrop of climate variability over the past ca. 20 ka.

Highlights

Over the last 30 years there has been an increase in the study of active and stabilized late Quaternary aeolian landforms and sediments in the eastern United States
Aeolian landforms and sediments on the S2 surface are restricted to elevations above 166 m, a conclusion that supports earlier findings (Morris and Pierce, 1967)
Consistent with other upper Ohio Valley studies (Rutledge et al, 1975; Chappell, 1988; Simard, 1989), aeolian landforms and sediments at Sandy Springs are restricted to the older, elevated S2 and S3 landforms

Summary

Introduction

Over the last 30 years there has been an increase in the study of active and stabilized late Quaternary aeolian landforms and sediments in the eastern United States. Studies largely have focused on aeolian depositional processes and geochronologies of dune fields, sand sheets, sandy loess or coversands, and loess. Aeolian sediments for some unglaciated valleys in eastern United States have been described in detail including the lower Mississippi Valley (e.g., Saucier, 1977; Rodbell et al, 1997; Rittenour et al, 2007; Markewich et al, 2015), aeolian landforms in other drainages such as the upper Ohio Valley have received less attention and remain largely undated (Rutledge et al, 1975; Chappell, 1988; Simard, 1989). To achieve a better understanding of past aeolian transport and deposition cycles for the eastern North America, additional geochronology and geomorphic histories are required for interior valleys, especially ones that have received limited attention

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