QUATERNARY GEOLOGIC EVOLUTION OF THE CROATAN BEACH RIDGE COMPLEX, BOGUE SOUND, AND BOGUE BANKS, CARTERET COUNTY, NC

Foraminiferal, lithostratigraphic, chronostratigraphic, and geophysical data were utilized to describe the Quaternary geologic evolution of the Croatan Beach Ridge Complex, Bogue Sound, and Bogue Banks, North Carolina. The late Pleistocene Croatan Beach Ridge Complex is separated from the adjacent modern barrier island, Bogue Banks, by Bogue Sound. Seventeen Geoprobe and vibracores were collected along shore-normal and shore-parallel transects from within the beach ridge complex, on the sound side of Bogue Banks, and in Bogue Sound. Seven depositional facies were identified using sedimentological data and a cluster analysis of foraminiferal samples from core material. An aeolian facies caps the Croatan Beach Ridge Complex. Three depositional facies were determined to be of normal marine salinity (high energy normal marine salinity, low energy normal marine salinity, and shallow inner shelf) and were found underneath the Croatan Beach Ridge Complex, Bogue Banks, and Bogue Sound. Flood tide delta, high salinity estuary and high energy back-barrier lagoon depositional facies characterize modern Bogue Sound.

Chronostratigraphic data combined with foraminiferal, sedimentological, and geophysical data suggest that the Croatan Beach Ridge Complex formed and prograded south during MIS 5a (~80-95 ka), producing a cape structure associated with the Suffolk Scarp. Similar data suggest aeolian reactivation of the upper segments of the Croatan Beach Ridge Complex during MIS 2 (~18 ka). OSL and radiocarbon age estimates and the occurrence of flood tide delta deposits indicate the formation of Bogue Banks by at least ca. 6 ka. Seaward and westward spit progradation of Bogue Banks began in the Pine Knoll Shores area ca. 1.7 ka and continued to the eastern tip of Salter Path until ca. 1.3 ka. This corresponds to a spit progradation rate of ~16 m/yr, a rate similar to those found at Oregon Inlet. Normal marine salinity conditions are present in Bogue Sound ca. 1.1 ka, suggesting removal of at least the narrowest parts of Bogue Banks, coincident with the collapse of segments of the southern Outer Banks barrier islands.