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Northeastern Section (39th Annual) and Southeastern Section (53rd Annual) Joint Meeting (March 25–27, 2004)

Paper No. 8
Presentation Time: 11:00 AM

LATE PLEISTOCENE FACIES DISTRIBUTION, SEA-LEVEL CHANGES, AND PALEOGEOGRAPHY OF THE INNER CONTINENTAL SHELF OFF LONG BEACH ISLAND, NEW JERSEY


UPTEGROVE, Jane, New Jersey Geol Survey, P.O.Box 427, Trenton, NJ 08625, SHERIDAN, Robert E., Geological Sciences, Rutgers University, 610 Taylor Rd, Piscataway, NJ 08854-8066, HALL, David W., New Jersey Geological Survey, Department of Environmental Protection, P.O.Box 427, Trenton, NJ 08625, WALDNER, Jeffrey S., New Jersey Geol Survey, Department of Environmental Protection, P.O.Box 427, Trenton, NJ 08625 and ASHLEY, Gail M., Earth and Planetary Sciences, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854, Jane.Uptegrove@dep.state.nj.us

This analysis of high-resolution shallow seismic data, vibracores, conventional radiocarbon and amino-acid racemization (AAR) dating of sediment samples determines the late Pleistocene facies distribution, sea-level changes and paleogeography of a 124 km2 area offshore Long Beach Island, New Jersey. In this passive margin setting, the combined effects of high-magnitude sea-level change (~70 to 120 meters) and low subsidence rate (limited accommodation space) result in incomplete stratigraphic packages on the inner shelf. This study examines Oxygen Isotope Stage (OIS) 1, 3, and 5 sequences and sea-level changes during OIS 3 and 5.

Contour plots of seismic reflector surfaces and isopachs, combined with sequence stratigraphic analysis reveal 1) a bay-mouth shoal complex in OIS 5 deposits; 2) a paleo shoreline in nearshore OIS 3c deposits; 3) Holocene shoals/swale topography; and 4) Pleistocene buttes (remnants of OIS 3 deposits cut by sub-aerial erosion and submarine currents). The large channel in the OIS 5 sequence is interpreted as comparable in size and internal structure to the modern Delaware shelf valley, with multiple channels 2-5 km in width and with 5 - 12 m of remaining valley fill sediments.

Steep seaward dipping reflectors located approximately 1.5 to 5 km from the present shoreline are interpreted as a barrier island/shoreface system, the top of which is found at water depths of ~15 to 19 m, pinning the 55 ka OIS 3c highstand. The mid-Wisconsinan shoreline previously reported more inshore and near Barnegat Inlet is re-interpreted as an OIS 5b feature, based on correlation of the Area C seismic data and tied to radiocarbon and AAR dates from cores.

The positive depositional features in the OIS 2/1 sediments are shore-detached ridges separated by wave- and current-eroded valleys.

In sequence stratigraphic terms, type 1 sequences predominate. In this inner shelf setting, the transgressive systems tract is the best-preserved part of the sequence.

Session No. 5

T5. Former Tidal Inlets and Breaches along Modern and Ancient Coasts: Formation, Evolution, and Geologic Record
Thursday, 25 March 2004: 8:00 AM-12:00 PM
Geological Society of America Abstracts with Programs. Vol. 36, No. 2, p.52
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