Shallowly-buried channel systems have been imaged on the New Jersey Shelf with high-resolution seismic imaging. These channels formed as riverine systems that occupied the exposed shelf during the Last Glacial Maximum, ~18 ka. Subsequent sea level rise ~15-12 ka modified the valleys, forming estuaries and filling the channels with estuarine sediments. The infill sediments within the channel provide evidence for the response of the shelf to the Late Pleistocene glacio-eustatic sea level rise, but little work has been done on samples from these strata. This study aids in the ground-truthing of previous stratigraphic results by analyzing the cores collected within the infill sediments. The seismic stratigraphy of fill sediments from the mid-shelf and outer-shelf channels are structurally dissimilar. The mid-shelf channel fill stratigraphy is dominated by finely-laminated U-shaped reflectors throughout the section, with cut and fill geometries. In contrast, the outer shelf channel fill stratigraphy is a well-ordered sequence of 4 identifiable, primarily flat-lying seismic units. We collected five cores in mid-shelf channels (~30 m water depth), one in an outer shelf channel (~80 m of water depth) and one core in the trangressive ravinement surface. Cores were logged for density and seismic velocity. Grain size analysis was conducted by settling column and laser particle size analyzer. Radiocarbon analysis of the stratigraphy was conducted with the shell fragments and organic mud within the samples. The foraminiferal assemblages aided in determining the depositional environment. Using these data I investigated the differences in depositional environment of the mid- and outer-shelf channels systems, and consider these results in the context of sedimentary models for estuarine processes. The radiocarbon dates and foraminiferal are consistent with channel infill in an estuarine environment. Grain size and density log data indicate that the mid-shelf channel fills are sandier than the outer-shelf channel fills, which leads me to infer that the sediment from the mid-shelf channels was deposited in a higher energy environment than that of the sediment in the outer shelf channels. The stratigraphic differences and locations of the channel systems are similar to the Zaitlin (1994) model of incised valley infill, but infill of the mid-shelf channel system could possibly be the result of a catastrophic meltwater flood event occurring ~14 ka as glacial lakes to the north broke their dams and flooded the mid-shelf. / text

Pleistocene New Jersey shelf sedimentology is strongly influenced by glacially driven sea level changes. A combination of regressive shoreline processes, subaerial exposure, fluvial downcutting, and deposition and reworking during transgression has influenced the NJ shelf sediment composition. Sediment provenance and transport history may be determined on a shelf environment through analysis of grain size distribution, heavy mineral content, magnetic mineral concentrations, and isotopic dating methods. A combination of surface grab and stratigraphic samples were analyzed within the study area. Relatively high percentages of heavy minerals were found in the 2 phi and 3 phi size fractions and hornblende grains provided K-Ar age values indicating two groups of sediment sources. The first source is Grenville with apparent ages above 900 Ma deposited during marine OIS 1. The second source is a mixed assemblage of Grenvillian and Paleozoic sources deposited during marine OIS 3, with apparent ages of approximately 850 ± 20 Ma.