Overpressure and Fluid Flow in New Jersey Continental Slope: Implications for Slope Stability and Cold Seeps

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Overpressure and Fluid Flow in New Jersey Continental Slope: Implications for Slope Stability and Cold SeepsPrincipal Investigator: Peter B. FlemingsObservations, theory, and experiments will be used to characterize the temporal and spatial evolution of fluid pressure and stress on the continental slope, offshore New Jersey. PI will image the porosity of the slope sediments using core data, well logs, and seismic velocities. Fluid pressures will be predicted using a porosity-effective stress relationship. This approach will provide a regional map of the porosity and fluid pressures. Greg Mountain (Lamont-Doherty Earth Observatory) will aid them in correlating the pressure distribution to key Miocene-to-present stratigraphic surfaces. Fluid pressures will also be correlated with exposed submarine canyons to evaluate the impact high pressures have on slope stability. A numerical model that couples consolidation theory and groundwater mechanics will simulate the porosity and pressure evolution. Porewater geochemical data will be used in concert with porosity data to validate the flow model. PI will perform laboratory experiments, at ExxonMobil Upstream Research Company, on samples from ODP Site 1073 to determine the compressibility and permeability of slope sediments. The experiments will also provide fluid pressure estimates that can be compared to the pressures predicted from porosity and those simulated in the flow models. After constraining the fluid pressures, their origins, and their distribution, we will evaluate the stress evolution, which is intimately tied to the fluid pressures and to slope stability.The proposed research will provide quantitative insights into how hydrodynamics and state of stress are linked on rapidly deposited margins. This local study has broad application to a variety of geological settings and societal problems. The study has the potential to estimate the location of sea floor seeps and the volume of fluids they expel; fluid flux relates to the size and diversity of biotic communities that use nutrients supplied by seep fluids. The pressure-stress field is important to understand for subsurface exploration and to evaluate slope stability. A definitive understanding of the origin of pressures and the focussed flows they can generate will be easily exportable to industry. The coupling of fluid pressure and stress will define the role excess fluid pressures play in sculpting continental slopes and may serve as a way to evaluate potential submarine landslide hazards.