Semester of Graduation
Master of Science (MS)
Geology and Geophysics
Although the Mississippi River and its tributaries have been investigated for many years, the alteration of the river through dams, levees, and diversions has affected how sediment is transported from source to sink (>103 y). Previous provenance research using detrital zircon U-Pb dating indicates a slow transport time from source-to-sink, but recent anthropogenic alterations of the river may potentially diminish the transportation time of heavy minerals due to an increase in flow efficiency. The objective of this study is to analyze the degree of buffering and recycling of Mississippi River sediment over a range of short time scales, spanning months to centennial scale over the last approximately 2500 years. I will be using deposits that pre-date levee construction and are preserved in meandering river point bars, such as the False River point bar in southern Louisiana. First, optically stimulated luminescence dating is used to accurately date the accretion history of the False River point bar. Secondly, detrital U-Pb zircon dating is used to define provenance and constrain variations in modern flux and possible anthropogenic influences on coarse-grained sediment within the Mississippi River. The importance of zircon U-Pb dating is also analyzed to determine if this method is suitable for large river systems with a statistically robust number of grains analyzed. Grain size is used to determine if the late Holocene False River point bar is similar to Modern River samples and if bias is created amongst grain size data. Lastly, to achieve further provenance discrimination, major element bulk sediment geochemical compositions are determined and compared to previous analyses in the Gulf of Mexico to determine short-term variability.
Neubeck, Nikki E., "Sediment Buffering and Recycling on an Annual to Centennial Scale Along the Mississippi River" (2022). LSU Master's Theses. 5510.