Ocean Drilling Program, United States

Sea-level changes have direct consequences for mankind; they profoundly affect shallow-water deposition and erosion, nearshore ecosystems, particle and nutrient transfer to the deep sea, and, at timescales of decades to centuries, the evolution of coastal civilization. Determining the timing, amplitudes, and causal mechanisms of sea-level variations, as well as their relation to the resulting stratigraphic record, continues to be a fundamental goal of the Ocean Drilling Program. Leg 174A will sample as many as six locations along the New Jersey shelf and upper slope as part of a long term initiative to investigate the Oligocene-Holocene history of sea-level change in a transect across the continental margin from the continental rise to the coastal plain. This initiative, the New Jersey Mid-Atlantic Sea-Level Transect (MAT), combines the resources of the Ocean Drilling Program, the National Science Foundation, and U.S. and State of New Jersey geological surveys. The primary goals of the transect are to (1) date unconformities (sequence boundaries) of Oligocene to Holocene age and to compare this stratigraphic record with the timing of glacial eustatic changes inferred from deep-sea delta (super 18) O variations, (2) place constraints on the amplitudes and rates of sea-level change that may have been responsible for unconformity development, (3) assess the relationships between depositional facies and sequence architecture, and (4) to provide a baseline for future scientific ocean drilling that will address the effects and timing of sea-level changes on this and other passive margins. An additional objective for Leg 174A is technical. The leg represents the first attempt by the Ocean Drilling Program to sample a thickly-sedimented continental margin in water <200 m deep.