Abstract:
The New Jersey/Mid-Atlantic Sea-Level Transect (MAT) has drilled on the New Jersey slope (ODP Legs 150, 174A), outer shelf (ODP Leg 174A), and Coastal Plain (ODP Legs 150X, 174AX) to investigate the history of global sea-level (eustatic) variations and their effects on the stratigraphic record. Middle Eocene to middle Miocene sequence boundaries were identified in NJ Coastal Plain and slope boreholes by integrating Sr-isotopic, magneto-, and bio-stratigraphy. For at least the past 42 m.y., these sequence boundaries correlate onshore to offshore, interregionally, and with glacioeustatic lowerings inferred from deep-sea d18O records, linking them to global glacioeustatic lowerings. Onshore studies also suggest that Cretaceous to early middle Eocene sequence boundaries may be linked to ice-volume changes in this purportedly ice-free world and provide preliminary estimates of eustatic amplitudes. Though our drilling and seismic imaging efforts have addressed major goals, our efforts have fallen short of our ultimate objectives because we have not: 1) sampled and dated upper Miocene-Pliocene sequences in detail; 2) evaluated the effects of local tectonics on the evolution of margin sequences; and 3) sampled facies that register the most sensitive record of sea-level change, the paleo inner shelf. Drilling in the Delmarva peninsula in May-June 2000 should provide dateable sequence stratigraphic records for the late Miocene-Pliocene and an along-strike sampling of Oligocene-Miocene sequence needed to evaluate tectonic effects. In addition, we propose to drill Sites MAT1-3 on the NJ inner shelf in 2001. These sites were chosen to provide definitive measures of sea-level amplitudes, to date seismic sequences where geometric relationships are clearest, and to evaluate models of sedimentation and facies distribution. By integrating our results with those derived from other sections in both shallow water and the deep sea, we anticipate that drilling MAT1-3 will allow us to: 1) provide estimates of eustatic amplitudes and generate a testable record of eustatic variations; 2) evaluate the effects of eustasy, tectonics, and sediment supply on the stratigraphic record; and 3) test models that predict the nature and distribution of sedimentary facies in passive margin strata.