Drilling the New Jersey shallow shelf to evaluate Miocene continental margin sequences, sea level, and resources

We review scientific ocean drilling of the New Jersey passive continental margin and the success of Integrated Ocean Drilling Program (IODP¹) Expedition 313 in addressing long-standing, fundamental issues of sequence stratigraphy, sea-level change, and resources. The New Jersey margin was targeted for study by several generations of ocean drilling because of its thick, prograding Oligocene to Quaternary sequences bounded by unconformities. Coring and logging on the onshore coastal plain (Ocean Drilling Program [ODP] Legs 150Xhttp://www-odp.tamu.edu/publications/citations/cite150X.html and 174AX), outer continental shelf (Leg 174A), and continental slope and rise (Legs 95, 150, and 174A) provided a chronology of sea-level lowerings but did not sample facies needed to evaluate Miocene sea-level amplitudes. Expedition 313 used a Mission Specific Platform (L/B Kayd) to drill on the shallow continental shelf, recover critical Miocene facies, particularly on clinoform foresets, and capture the full amplitudes of relative sea-level changes. Expedition 313 overcame challenging borehole conditions and recovered a total of 1311 m of core at three sites (81 % recovery) that: (1) correlated difficult-to-date nearshore-shelf facies to the time scale with resolution better than ±0.5 million years (Myr); (2) tested and confirmed that sequence boundaries are a primary cause of seismic reflections on siliciclastic shelves; (3) tested sequence stratigraphic models with core-log-seismic integration; and. (4) provided a record of paleodepth changes through time that constrained amplitudes of Miocene sea-level change, including the influence of mantle dynamic topography. The New Jersey relative sea-level estimates are similar to those obtained using stable isotopes and Mg/Ca paleothermometry, showing that GMGSL (“eustasy”) varied with 10–60 m scale amplitudes on the Myr scale. Drilling beneath the shallow continental shelf also identified groundwater sources, including seawater, deep-sourced brines, and meteoric fresh water, that represent potential resources for future generations. Studies of this margin have implications for future subsurface storage of supercritical CO₂ and geotechnical issues relating to the location of offshore wind infrastructure. Expedition 313 demonstrated the feasibility of continuously recovering and logging strata in shallow water, providing constraints on sea level, sequences, hydrogeology, and resources.