Master of Science (MS)
Geology and Geophysics
This study investigated the shallow subsurface of the Lower Coastal Plain of South Carolina in order to determine the sea-level history and stratigraphic architecture preserved within several emergent shoreline complexes. The absolute age of each shoreline complex was estimated using single-aliquot regenerative-dose (SAR) optically stimulated luminescence (OSL) techniques. The resulting geochronology was incorporated into a high-resolution stratigraphic framework defined by ground penetrating radar calibrated with deep sediment cores, many of which contain a complete sequence of highstand deposition. Three emergent barrier complexes were identified within the Lower Talbot, Pamlico, and Princess Anne terraces, and assigned to sea-level highstands during interglacial periods between 240 to 80 ka, which correspond to marine isotope stages (MIS) 7, 5e, and 5a. The stratigraphic architecture of each shoreline complex consists of a distinct succession of lithofacies deposited in lagoonal, shoreface, and eolian environments typical in a siliciclastic shoreline setting. Relict shoreface facies contain swash zone strata that precisely document the peak elevations attained by specific relative sea-level highstands. First, a transgression during MIS 7 (230 ka) emplaced swash zone strata at 12 ±1 meters above present day sea-level (mASL). This was followed by two separate transgressions during MIS 5e (140 to 125 ka) that attained elevations of 9 and 6 ±1 mASL, respectively. Finally, a MIS 5a (80 ka) highstand peaked at 5 ±1 mASL. The present day elevations of the MIS 7 and MIS 5e highstand deposits can be explained with a consistent uplift rate of ~5 cm/kyrs. However, the elevation of MIS 5a deposits conflicts with most global estimates of this highstand. This implies the MIS 5a highstand was actually closer to present day sea-level, in a global sense, or that complex glacio-hydro-isostatic effects have played a major role through multiple glacial-interglacial cycles in this region.
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Willis, Russell, "Genetic stratigraphy and geochronology of last interglacial shorelines on the central coast of South Carolina" (2006). LSU Master's Theses. 2657.