DEPOSITIONAL SEQUENCE STRATIGRAPHY OF TURONIAN TO SANTONIAN SEDIMENTS OF THE NORTH CAROLINA COASTAL PLAIN

Sequence stratigraphic analyses are typically used to provide an improved understanding of sea level rise and fall in coastal regions. This integrated relative sea level approach helps researchers concentrate on broader aspects of geologic history, particularly with regard to distinguishing local relative sea level changes from eustatic changes. Using the USGS Kure Beach and Elizabethtown cores from the Coastal Plain of North Carolina, integrated analysis of grain-size data, geophysical logs, biostratigraphy, and ⁸⁷Sr/⁸⁶Sr isotopic data were used to develop a sequence stratigraphic framework for the Turonian to Santonian sediments of this region. Three Turonian to Santonian sequences in the Elizabethtown core and six in the Kure Beach core are identified. The sequences from oldest to youngest are Clubhouse II, Fort Fisher I, Fort Fisher II, Collins Creek I, Collins Creek II, Pleasant Creek I, and Pleasant Creek II.

Regional correlation of the NC sequences to those identified in the New Jersey Coastal Plain allows for the identification of global versus regional sea level events. The Clubhouse II sequence correlates to the Bass River III sequence of NJ, and the sequence boundary that separates Clubhouse II from Fort Fisher I in NC corresponds to the KTu4 sea level regression that marks the end of the early Turonian highstand. The Fort Fisher II sequence represents a remnant of the latest Turonian; there are no correlative sediments in NJ, which were stripped away during the KTu5 sea-level regression. The Collins Creek I (Coniacian) and Collins Creek II (Santonian) sequences correlate to the Magothy III and Cheesequake sequences of NJ, respectively. A thick section of Pleasant Creek I (Santonian) is identified from both cores but has no correlative sequence in NJ. This expanded section may be a reflection of local deposition related to flexure of the Cape Fear Arch. The Pleasant Creek II sequence (Santonian) correlates to the Merchantville I sequence in NJ.