An optical age chronology of Late Pleistocene fluvial deposits in the northern lower Mississippi valley

The lower Mississippi valley (LMV) contains many large braided channel belts that are preserved west of the Holocene floodplain. Previous efforts to establish geochronologic control on channel-belt construction have been hindered by the lack of organic material for radiocarbon dating. Luminescence techniques provide a burial date for the sediment itself and may prove useful in this context. Samples from three channel belts in the northern LMV were analyzed using the single aliquot-regenerative technique on 90–125 μm quartz. Optical ages (19.7–17.8, 16.1–15.0 and 12.5–12.1 ka) are consistent with geomorphic relationships and indicate that channel belts were formed in the late Pleistocene under glacial conditions. These optical ages provide the first detailed chronology of LMV channel-belt formation and are the first step towards developing a chronology for the entire LMV.