LATE QUATERNARY SEQUENCE STRATIGRAPHY OF A SLOWLY SUBSIDING PASSIVE MARGIN, NEW-JERSEY CONTINENTAL-SHELF

High-resolution seismic profiles over a 25,000 km(2) area off New Jers ey illustrate the effects of high-amplitude, high-frequency eustasy on a slowly subsiding (<0.2 mm/yr) passive margin. Analysis of 1600 km o f Geoptlse(TM), Uniboom(TM), Minisparker(TM) and air-gun profiles reve als four depositional sequences with a maximum total thickness of 100 m at the shelf edge. Correlation of these sequences to biostratigraphi c and aminostratigraphic data from drill sites suggests all of these s equences may be postoxygen isotope stage 6 (similar to 140 ka). Sequen ces I and IV appear to correspond to the major glacial-interglacial se a level changes (similar to 120 m) during oxygen isotope stages 6/5 an d 2/1, respectively. Sequences II and III reflect smaller scale sea le vel fluctuations. AU sequence boundaries are interpreted as type 1, an d sequences are predominantly composed of transgressive systems tracts (TST) and lowstand systems tracts (LST), Much of the TST was deposite d as incised-valley fills; parasequences in the TST commonly are isola ted and fragmented. The low subsidence rate and high-frequency (20 k.y .) eustatic oscillations result in extensive erosion and reworking of previously deposited sediments, both by fluvial incision during lowsta nds and marine erosion during transgressions and highstands. On contin ental margins where subsidence rates and sediment supply are low relat ive to rates of eustasy, sequences are thin, fragmented, and difficult to correlate. Local effects, such as shifting river drainage, salt di apir movements, and glacial isostasy, can significantly influence sequ ence preservation on such margins.