PALEODRAINAGE CONTROLS ON COASTAL AND SHELF CONFIGURATION IN A MID-LATITUDE PASSIVE MARGIN

Understanding geologic framework controls on continental shelf evolution is critical to predicting future shelf and coastal change. In this study we integrate high-resolution geophysical data, including quasi-3-D chirp and multi-channel seismic reflection profiles, with hydrographic, geochronologic and vibracore datasets collected over ~5,200 km² of the Delmarva continental shelf. We analyze the geometry and distribution of underlying stratigraphic units and unconformities with respect to modern shelf geomorphology and coastal properties. We observe several correlations between relict framework elements and modern shelf and coastal features. At multiple locations, buried paleoinlet deposits coincide spatially with modern inlets. Two paleovalleys, interpreted to have formed during the last two sea-level lowstands (~19 ka and ~150 ka), trend through the subsurface toward the head of Norfolk Canyon. We also resolve a spatial relationship among a Pleistocene fluvial plain deposit, shelf sand bodies and shoreline stability which suggests that the underlying Pleistocene deposit exerts an influence on modern inner continental shelf sedimentary processes. These results are important for studies of landscape and coastal evolution and can support decision making and development efforts on the mid-Atlantic continental shelf.