LATE CRETACEOUS (CAMPANIAN AND MAASTRICHTIAN) TO EARLY PALEOGENE PALEOCEANOGRAPHIC CYCLICITY, SOUTHEASTERN NORTH CAROLINA, USA

Sequence stratigraphic analysis using samples, geophysical logs, and biostratigraphic data from USGS core holes KB (Kure Beach), Hilton Park (Wilmington), and Black Rock Landing (Cape Fear River) identified four partial or complete late Cretaceous sequences. Sequence 1 (Campanian) is dominated by dirty calcareous sand. Mean grain size of sand fraction is 1.93 F; mean carbonate wt. % is 25.9%. This partial sequence is interpreted as a highstand systems tract (HST). A Type-1 sequence boundary separates sequence 1 from the next sequence; it is reflected by an irregular surface and the absence of calcareous nannofossil zones CC24 and CC25a. Sequence 2 (Maastrichtian) is characterized in its lower part by clean, fining-upward (1.7 F to 3.4 F) calcareous sand interpreted as a lowstand wedge (LSW). The LSW is overlain by a wackestone with a mean sand size of 2.92 F and a mean wt. % carbonate of 65.2%, interpreted as a TST. The overlying HST is dominated by intercalated muddy carbonate, skeletal wackestone, and mollusk-fragment carbonate sand. Mean sand size is 2.27 F; mean wt. % carbonate is 39.3%. A Type-2 sequence boundary separates sequence 2 from the next sequence. Sequence 3 spans almost 50% of the described section in KB core. Basal coarsening upwards-calcareous sand is interpreted as a shelf margin deposit (SMST). Mean sand size is 2.63 F; mean wt. % carbonate is 34.1%. Above the SMST clay and Foraminifera increase. This section is interpreted as a TST grading into the CI. Mean grain size fines to 3.12 F and mean wt. % carbonate increases to 47.4%. The HST consists of a lower aggradational parasequence that shoals upward from muddy to sandy carbonate with evidence of storm winnowing. Mean grain size is 2.64 F; mean wt. % carbonate is 51.8%. The younger, progradational parasequence shoals to a sandy, molluscan-mold packstone. Mean sand size is 1.64 F; mean wt % carbonate is 56.7%. A dissolution surface above the packstone represents the 68 Ma unconformity. The youngest sequence (4) has variable lithology. A nearly pure carbonate is overlain by sand. The youngest sediments are clay-rich and poorly sorted. This final sequence is interpreted as being latest Cretaceous (?) grading into the earliest Danian (?).