Date of Graduation
5-2026
Document Type
Thesis
Degree Name
Master of Science in Geology (MS)
Degree Level
Graduate
Department
Geosciences
Advisor/Mentor
Guccione, Margret
Committee Member
Shaw, Jack
Second Committee Member
McGilvery, Mac
Keywords
Arkansas River; Cimarron River; Oklahoma; osage plains; sand dunes
Abstract
Quaternary aeolian and fluvial deposits along the Arkansas and Cimarron Rivers in Osage and Pawnee counties of central Oklahoma, record Late Pleistocene and Holocene fluvial landscape history in the eastern Osage Plains. Sediment supply, climate variability, channel incision, and channel migration control this landscape evolution. Sediment supply of both streams is dominantly sand. Late Pleistocene and Holocene precipitation have varied with periods of drought alternating with increased precipitation and warming. The study area is near the eastern boundary of substantial aeolian activity with drought and aeolian reworking of fluvial sand more severe to the west. This study examines the sediment, landforms, and their ages within an Arkansas River meander and a Cimarron River meander 30 km and 80 km respectively upstream of their confluence. Low Soil Moisture Index (SMI) values and soil maps were useful in identifying sand distribution within the Arkansas and Cimarron River meander bends of the study areas and the possibility of aeolian deposits. SMI mapping reveals that dunes within the study area exhibit higher SMI values than mapped dune fields farther west in Oklahoma and Kansas, reflecting increased precipitation, greater vegetative cover, and enhanced soil development at the eastern edge of the Osage Plains. Low SMI values, weak soils, scarce vegetation, and extensive dune fields characterize western dune fields, consistent with the dry climatic conditions. In contrast, dunes along the Arkansas and Cimarron Rivers in the study area are smaller, less extensive, and were periodically stabilized and weathered during more humid climatic conditions. Fluvial and aeolian deposits are preserved within both Arkansas and Cimarron River meander bends examined. Various techniques were used to distinguish aeolian dune or sand sheet deposits from fluvial point-bar sand, including grain-size distributions, sedimentary structures, and geomorphic expression. Fluvial deposits are dominated by medium sand, may be laminated or gently dipping and have an undulating point-bar topography with a low relief of 1-2 meters. In contrast, the aeolian deposits in the region are reworked fluvial deposits and are dominated by fine and very fine sand that can be massive, have weakly developed bedding, or have cross beds dipping in a variety of directions and ripple marks. Where dunes are present, the undulating topography has a relatively high relief of 3-5 m. The sand, either fluvial or aeolian, can be dated using Optically Stimulated Luminescence (OSL), which measures the last time the sand was exposed to sunlight. A low terrace, 19 m above the Cimarron River is OSL dated 22.80 ka and has a well-developed soil with Bt horizons. The upper edge of the Arkansas River floodplain, 9 m above the channel, is 10.76 ka, suggesting that incision of these streams occurred between 22.8 and 10.8 ka, during the latest Pleistocene or earliest Holocene. Four other OSL dates on both the Arkansas and Cimarron River floodplain deposits of aeolian origin 5-8 m above the channel are all Late Holocene and range from 3.76 to 0.87 ka. Using all these dates, Late Pleistocene to late Holocene incision rates for both streams are similar, 0.0008 m/year. During the Late Holocene, the incision rates increased by nearly an order of magnitude to 0.001 to 0.004 m/year, perhaps due to aeolian aggradation. Similarly, the migration rate of both these channels was relatively slow during the Late Pleistocene to Late Holocene, 0.047 to 0.077 m/year, and was much faster, 0.13 to 0.34 m/year in the last 3.76 ka, again perhaps due to aeolian reworking of fluvial deposits. Soil development is consistent with OSL ages. At the only terrace examined in this study there was no evidence of dunal landforms or aeolian sediment along the Cimarron River, though terrace dunes are reported nearby. Here a strongly developed soil with Bt horizons is formed in fluvial sediment dated 22.80 ka. At two additional locations at the highest part of the Arkansas River floodplain, no overlying aeolian sediment is present and the strongly developed soils in the 10.80 ka old fluvial sand also have Bt horizons. At the six additional locations dated Late Holocene on both the Arkansas and Cimarron floodplains, surface soils are only weakly developed with Bw horizons or no B horizon. On the Cimarron River floodplain, both Late Holocene dune landforms and aeolian deposits with weak soils are present. On the Arkansas River floodplain multiple aeolian deposits are present with weak soils separating them and forming at the land surface. There are no dune landforms, however, so it is possible that the deposits may be episodically deposited as sand sheets with relatively short periods of time between depositional events when the surface was weathered before burial by the next deposit.
Streaming Media
Citation
Duncan, B. A. (2026). Age and Characteristics of Quaternary Fluvial and Dune Deposits Along the Arkansas and Cimarron Rivers in Osage and Pawnee counties, Oklahoma. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/6119
