LATE CRETACEOUS SEQUENCE STRATIGRAPHY OF THE DIXON AND KURE BEACH CORES, ATLANTIC COASTAL PLAIN, NORTH CAROLINA, USA

Cretaceous depositional sequences in two cores (Dixon and Kure Beach) from North Carolina were identified using lithologic, biostratigraphic and ⁸⁷Sr/⁸⁶Sr-isotope data. Eight depositional sequences are identified in the Dixon core and correlated to the depositional sequences in the Kure Beach core; two additional basal sequences are present in Kure Beach. Sequence 0 is the oldest sequence identified at Kure Beach, where a single ⁸⁷Sr/⁸⁶Sr date of 89.1 Ma was obtained. This sequence represents the progradation of a fluvial system during a sea-level lowstand. Sequence 1 represents a proximal offshore to shoreline facies and is assigned to nannofossil Zone CC13b, (⁸⁷Sr/⁸⁶Sr dates of 87.1 to 87.3 Ma). The Pleasant Creek I sequence is Santonian in age, and is assigned to nannofossil Zones CC15 and CC16. Eight ⁸⁷Sr/⁸⁶Sr dates between 88.2 and 87.0 Ma were obtained in the Kure Beach core and a single date of 86.1 Ma was obtained from the Dixon core. Pleasant Creek I at Dixon consists only of the highstand system tract sediments. At Kure Beach, this sequence ranges from distal offshore to intermediate distal offshore and proximal offshore facies. The Pleasant Creek II sequence in Kure Beach is assigned to calcareous nannofossil Zones CC16 through CC18a. It yielded ⁸⁷Sr/⁸⁶Sr dates from 87.0 Ma to 83.8 Ma. The basal part of Pleasant Creek II in the Dixon core is slightly truncated and falls within nannofossil Zones CC16 and CC17, with⁸⁷Sr/⁸⁶Sr dates between 85.0 Ma to 83.6 Ma. The Pleasant Creek II sequence is part of an intermediate distal offshore facies. The Campanian Tar Heel I sequence is assigned to nannofossil Zones CC17 and CC18 (⁸⁷Sr/⁸⁶Sr dates between 81.5 to 80.8 Ma) in the Dixon core and to Zones CC18 and CC19 (⁸⁷Sr/⁸⁶Sr dates between 83.2 to 80.0 Ma) at Kure Beach. Tar Heel II is assigned to Zone CC19 in the Dixon core and to Zones CC19-CC20 in the Kure Beach core. ⁸⁷Sr/⁸⁶Sr dates are between 79.4 and 75.6 Ma. Donoho Creek I and II sequences are thin and variably assigned to Zones CC20, CC21, CC22c, CC23 and CC24 in both cores. ⁸⁷Sr/⁸⁶Sr dates of 78.1 Ma and 72.7 Ma were produced for Donoho Creek I, and 71.4 Ma to 68.6 Ma for Donoho Creek II. The Maastrichtian Peedee I sequence is assigned to Zones CC24 and CC25a/b (⁸⁷Sr/⁸⁶Sr dates 69.3 to 66.9 Ma), and Peedee II is assigned to Zones CC25b and CC26a (⁸⁷Sr/⁸⁶Sr dates 66.4 to 65.2 Ma).