Abstract

Shoreline sedimentation at Stone Harbor and Barnegat Bay, New Jersey, was studied to distinguish between sediments of the beach, dune, lagoon, and marsh. Investigation began with the individual grain and proceeded to the properties of the locus itself. Under the electron microscope, solution pits in aqueous sand are seen to follow crystallographic form, as opposed to irregular collision pits for wind-abraded grains. The influx layer, the smallest unit of sedimentation, shows lateral variations, particularly on the Barnegat Bay beach, where coarse particles concentrate at the wave marks. Influx layers differ in their properties within the 4 environments. The skewness of grain size distributions (a-axis of quartz grains in phi) changes from negative to positive from beach to lagoon. Lagoonal shore sands along the barrier island at Barnegat Bay show good sorting and concentration of heavy minerals. Analyses of differences in the means of the lengths of quartz grains indicate that the components of variance are heterogeneous and that each environment must be considered as a separate problem. At Stone Harbor, radioactive particle counts above background increase gradually from beach to lagoon and marsh. At Barnegat Bay, a sharp difference exists between beach and dune against lagoon and marsh. Mineral composition studies indicate that the beach contains more quartz than the dune at both Stone Harbor (71% vs. 54%) and Barnegat Bay (95% vs. 88%). Study of sediment color shows that wave lengths of reflected light for beach sand are confined to a narrow range in percent reflectance (26.8-30.2 for violet and 41.5-50.0 for red). Dune sands show a wider range in reflected light wave length, which is caused locally by organic material (Barnegat Bay) or heavy minerals (Stone Harbor). Dark portions of the lagoon are more uniform than the marsh in both locations. Vegetative organic matter is considered the main source material for petroleum. The amount of organic matter in the marsh (15%) exceeds that of the lagoon (5%) with a correspondingly higher amount of hydrocarbons (mostly paraffins), 0.405 vs. 0.204 for nuclear magnetic resonance. Therefore, a likely future source-bed for petroleum at Stone Harbor is the marsh. The most likely future reservoir rocks are main lagoonal channels, tidal deltas and the barrier island.

First Page Preview

First page PDF preview
You do not currently have access to this article.