Caterine Schuur Duncan1,
John A. Goff2,
James A. Austin2,
Hilary C. Olson2,
Neal W. Driscoll3
(1) University of Texas at Austin, Austin, TX
(2) University of Texas, Austin, TX
(3) Woods Hole Oceanographic Institution
Abstract: Very high-resolution seismic stratigraphic invesstigation of the last sea level cycle; latest Quaternary stratigraphy and seafloor morphology of the New Jersey inner shelf
Seafloor morphology and shallow stratigraphy on the New Jersey inner shelf (~20-45 m w.d.) describe the latest Quaternary geologic history of this stable, sediment-starved, siliciclastic margin. We use ~200 line-km of ultra-high resolution (1-15 kHz) chirp sonar profiles, ~250 km2 swath bathymetry and sidescan sonar images (pixel size ~5 m2), and ~300 precisely located grab samples to track the evolution of depositional systems across the inner shelf during the last global eustatic cycle (~150 kyrs B.P. to Present).
Chirp profiles show detailed stratigraphy in the upper ~30 m of the section, including two incision surfaces buried ~5 m and ~25 m below the seafloor. These may be the subaerial exposure surfaces carved during the last two glacial maxima, ~22 kyrs B.P. and ~150 kyrs B.P. We also observe the relationships of these incisions to regional stratigraphic architecture, and complex seismic patterns within individual "channels."
There is a mismatch between seafloor morphology and shallow stratigraphy on the New Jersey shelf. With the exception of a high-backscatter lineament that appears related to a large buried channel, the seafloor shows no evidence of processes prior to Holocene transgression. Seafloor morphology includes the Mid-Shelf paleo-shore (~45 m w.d.), a bathymetric step presumably formed during a Holocene stillstand, oblique ridges, and flow-transverse dunes, the morphology of which suggest shoreward-directed modern currents. These very high-resolution, "nested" data provide an unprecedented level of stratigraphic detail linking outcrop-scale, process-based geomorphology and studies of the older geologic record based on more conventional, larger-scale seismic data.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana