--> Abstract: Quaternary Seismic Stratigraphic Framework of the Southern Albemarle Embayment: The Sequence Stratigraphic Response to Evolving Paleotopography, by Michael Buckner, David Mallinson, Stan Riggs, Robert Thieler, and David Foster; #90039 (2005)

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Quaternary Seismic Stratigraphic Framework of the Southern Albemarle Embayment: The Sequence Stratigraphic Response to Evolving Paleotopography

Michael Buckner1, David Mallinson1, Stan Riggs1, Robert Thieler2, and David Foster3
1 East Carolina University, Greenville, NC
2 U.S. Geological Survey, Woods Hole, MA
3 U.S. Geological Survey,

Pamlico Sound is a drowned river estuary on the North Carolina continental margin, underlain by a regional depositional basin called the Albemarle Embayment. Seven hundred fifty kilometers of high-resolution single channel seismic data were collected in the Pamlico Sound of North Carolina. These data show the regional geologic framework, distribution and character of Pliocene and Quaternary depositional sequences and associated incised paleodrainage systems. Deposits represent the updip component of transgressive and highstand systems tracts in a filling basin. Sequence boundaries are primarily Type 1 based on the observation of complex incised channel-fill facies bounded by high amplitude seismic reflections. Additional surfaces (eg. marine flooding surfaces and ravinement surfaces) are also evident. At least eighteen Quaternary seismic sequences have been identified within the basin. Quaternary sediments lie on a northward dipping unconformity that is likely the top of the Pliocene, ranging from 75 meters below sea level (mbsl) in the north to approximately 37 mbsl in the south. Data reveal a complex fill history characterized by multiple large (30+ meters deep, multiple km wide) incised valleys and numerous smaller incised channels within the Quaternary section. Paleochannels provide information concerning the locations, sizes, geometries, orientations and fill history of the fluvial systems that previously occupied the basin during the Quaternary. Channel-fill facies seen in the data range from steeply dipping clinoforms to horizontal beds. Progradation of clinoforms dominantly trends to the east with few trending to the northwest. Understanding past basin dynamics in response to sea-level change will aid in refining sequence stratigraphic models, and help predict future coastal change as sea-level continues to rise.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005