The sequence stratigraphic development of the subsurface Paleogene, Albemarle Basin, North Carolina, was defined using well cuttings and wireline logs tied into largely published biostratigraphic and available seismic data. Facies include: silty and shelly sands and shell beds (estuarine/lagoon/protected inner shelf facies); clean quartz sands and sandy mollusk-fragment grainstones (shoreface/shallow shelf); phosphatic hardgrounds (current and wave-swept shoreface and shallow shelf); bryozoan and echinoderm grainstones/packstones (storm reworked middle shelf); and fine skeletal wackestones and planktonic marls (slightly storm-winnowed to sub-wave base, deeper shelf). Paleogene deposition on this high-energy, open-shelf was characterized by a distinctive shelf profile of inner shelf and inner shelf break, deep shelf and continental shelf/slope break. The successive positions of terminal supersequence inner-shelf-breaks parallel the modern day continental margin and its onshore arches. Thickness trends were strongly controlled by more rapid subsidence within the Albemarle Basin. The Paleocene supersequence is dominated by deep shelf marl and developed following flooding after the latest Cretaceous low-stand. Major shallowing occurred at the end of the Early Paleocene and near the end of the Late Paleocene. The Eocene supersequence developed following lowstand deposition (evident on seismic) just off the terminal Paleocene depositional shelf break. With flooding, a major transgressive sediment body developed (Pamlico spur), that formed a 50 km wide by 50 m high promontory at the inner shelf break, followed by HST progradation of quartzose and bryozoan-echinoderm open shelf carbonates that filled in the laterally adjacent shelf topography. This was followed by ancestral Gulf Stream incision of the southeast-trending, shallow shelf to the south, and deep shelf further northeast. Late Eocene-Oligocene deposition was initiated with localized lowstand sedimentation off the earlier terminal inner shelf break, followed by thin regional marl deposition and widespread highstand inner shelf, quartz sands and quartzose carbonates. Localized Late Oligocene lowstand deposition occurred along the earlier Oligocene terminal inner shelf break, followed by widespread deposition of quartzose facies over the shallow shelf. Oligocene units on the deep shelf were modified by highstand Gulf Stream scour. / Ph. D.

Cores, quarry exposures, and exploratory wells in the Paleogene Albemarle Basin, North Carolina sample the transition between the southern carbonate and northern siliciclastic provinces of the eastern U.S. continental shelf succession. The study area includes the relatively positive Cape Fear Arch on the Onslow Block to the south, and the slowly subsiding (1.5 cm/ky) Albemarle Block to the north. The Paleogene supersequence set boundary is a hardground on Cretaceous shoreface/shallow-shelf mollusk facies. It is overlain by a thin Paleocene sequence of deeper offshore, glauconitic fine sands to deep marine silt-shale. Five regionally mappable, vertically stacked Eocene sequences are 0 to 30 m thick and contain coastal sands, shoreface sandy-mollusk rudstones, offshore bryozoan grainstone-packstones and subwave base fine wackestone-packstone and marl. The Eocene sequences commonly are bounded by hardgrounds, overlain by thin local lowstand sands and consist of a thin transgressive unit (commonly absent), overlain by an upward shallowing highstand marine succession. On the arch, lowstand and transgressive units may be condensed into lags. The Lower Oligocene succession on the arch has a single marl to fine foram sand dominated sequence whereas downdip, two to three sequences are developed, capped by nearshore sandy molluscan facies. The Upper Oligocene is dominated by possibly three sequences composed of basal, thin sands up into variably sandy mollusk rudstone. Sequence development was influenced by differential movement of the basement blocks, coupled with increasing 3rd order eustatic sea level changes during global cooling. This was coupled with swell-wave and current sweeping of the shelf that effectively decreased available accommodation by 20 to 30 m, and generated the distinctive hardgrounds on sequence boundaries, and variable development of lowstand and transgressive system tracts. The well developed highstands reflect maximum accommodation allowing deposition of an upward shallowing succession that terminated at the depth of wave abrasion on the open shelf. The sequence stratigraphic development contrasts markedly with that from tropical shelves. / Master of Science