Doctor of Philosophy (PhD)
Oceanography and Coastal Sciences
Sediment transport and slope stability are fundamental organizing agents of the geological record. These processes have been extensively studied along the northern margin of the Gulf of Mexico basin for both basic and applied purposes, but our knowledge of them is limited by the spatial and temporal sampling capabilities of traditional geologic oceanographic surveying tools such as coring, single-beam echosounders, and sidescan sonar. This dissertation seeks to update the state of knowledge regarding northern Gulf of Mexico sediment transport and slope stability from annual to millennial timescales, primarily using relatively high-resolution acoustic geophysical tools such as swath bathymetric echosounders and swept-frequency subbottom echosounders. There are three primary findings of this dissertation: (1) the subaqueous Mississippi River Delta Front is a zone of active downslope sediment flux in lieu of major hurricane passage, and the volume of sediment transported downslope during major hurricane and non-major hurricane containing intervals is comparable, (2) mud-capped dredge pits used for coastal restoration projects in Louisiana can be used as proxies for sediment deposition and slope stability along the Inner Continental shelf, and highlight the important role resuspension and slope failure play in decadal and longer-scale sediment accumulation in this environment, and (3) a drowned forest of age > 40,000 years before present found offshore Gulf Shores, Alabama likely represents a unique or at least fairly localized depositional environment that preserved entire tree stumps during geologic periods that favor destruction of sedimentary fabric, including sea level lowstand and transgression.
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Obelcz, Jeffrey Blake, "Sediment Transport and Slope Stability in the Northern Gulf of Mexico" (2017). LSU Doctoral Dissertations. 4293.
Available for download on Saturday, February 23, 2019