| Summary: | 2-D seismic, wireline log, and core data at ODP Leg 174A Sites 1071 and 1072 on the outer continental shelf of New Jersey reveal two major depositional sequences of late Miocene–Pliocene and Pleistocene age. The late Miocene–Pliocene sequence is a thick (∼100 m) deepening-upward succession landward of the clinoform rollover and a shoaling-upward succession seaward of the clinoform rollover. The Pleistocene sequence deepens abruptly near its base, shoals upward, and then deepens again before it is truncated by its overlying unconformity. There is no onlap onto clinoforms (no lowstand wedge) in either sequence. Sequence stratigraphic analysis and a geometric depositional model are used to interpret that the unusually thick transgressive component of the late Miocene–Pliocene sequence was formed by high-frequency eustatic cycles (1–2 m.y.) superimposed on a longer-term eustatic rise (∼5 m.y.). This conclusion is supported by independent evidence of eustasy. The sequences of this study are correlated to sequences in the North Atlantic coastal plain and in the Great Bahama Bank. These sequences have very different architectures than underlying middle Miocene sequences, which contain thick lowstand wedge deposits, and are interpreted to have formed by high-frequency eustatic cycles superimposed on longer-term eustatic fall.
|
|---|