CORRELATION AND IMPLICATIONS OF EARLY MIOCENE ONSHORE AND OFFSHORE SEQUENCES, NEW JERSEY COASTAL PLAIN (LEGS 150X AND 174AX) AND SHELF (EXPEDITION 313)

We correlated onshore New Jersey coastal plain sequences Kw2 and Kw1 with offshore shallow shelf sequences m5.4 (ca. 18.0-17.7 Ma) and m5.8 (ca. 20.1-19.6 Ma), respectively, using multichannel seismic profiles (MCS), stratal stacking patterns in cores and well logs, and chronostratigraphy. Seismic-core-log correlations at offshore Expedition 313 Sites M27 and M28 allow extension of lithologic and chronostratigraphic data into the time domain of seismically well imaged sequences. These sequences were traced shoreward using R/V Cape Hatteras 0698 MCS data to onshore Atlantic City, Cape May, Ocean View, Cape May Zoo coreholes, and adjoining boreholes. Depositional environments of the sequences were evaluated by analyzing lithology, well logs, and benthic foraminifera-derived paleobathymetric estimates to constrain environmental changes in the sequences. Age resolution of the sequences was determined by Sr analyses onshore and Sr and biostratigraphy at offshore locations. The onshore sequences Kw2 (ca. 17.5-15.1 Ma) and Kw1 (ca. 20.4-19 Ma) are thick (>50 m) and contain an upper (Kw2b and Kw1b) and lower (Kw2a and Kw1a) Myr-scale sequence. Both onshore upper sequences Kw2b and Kw1b were found to be single sequences. However, the Kw2a sequence was determined to be a composite sequence containing 3 higher order (100/400 kyr) sequences (Kw2a1, Kw2a2, and Kw2a3) that correspond to 3 sequences within offshore composite sequence m5.4 (m5.4-1, m5.34, and m5.33). We note that the lower Kw1 sequence (Kw1a) also contains three higher order sequences (Kw1a1, Kw1a2, and Kw1a3), prompting us to reexamine offshore sequence m5.8. We conclude that as resolution increases, the nearshore stratigraphic record can be shown to be a stacking together of sequences on various scales that is remarkably incomplete.