OSL chronology of middle to late Holocene aeolian activity in the St. Anthony dune field, southeastern Idaho, USA

Late Quaternary aeolian dune systems in the Great Plains and western U.S. are valuable archives of past climate variability. This study investigates the St. Anthony dune field, located in the eastern portion of the Snake River Plain in southern Idaho. The current semi-arid climate of the region allows for a central core of active dunes that is approximately 450 km2 in area and includes compound crescentic, blowout, falling, and climbing dunes that range in height from 15 to 121 m. The surrounding region is characterized by ∼20,000 km2 of relic parabolic, linear, and complex linear dunes that are currently fixed by vegetation.This study examined nine samples collected from the fixed dunes that surround the active core of the St. Anthony dune field. Optically stimulated luminescence (OSL) dating results indicate that these fixed dunes were mobile and actively accreting ∼6.6 ka (middle Holocene) and 1.0–2.0 ka (late Holocene). Evidence for activation of a large region currently occupied by stable dunes suggests these periods were characterized by hydrologic deficit and/or warmer climate conditions than currently exists. This research provides new information regarding the depositional timing of the St. Anthony dunes and assists in providing evidence of palaeo-climatic conditions for the eastern Snake River Plain during the middle to late Holocene.