LATE PLEISTOCENE IRD ON THE NEW JERSEY SHELF?

The geology of the New Jersey margin has a complex history with multiple past events working together to create the existing shelf. Glacially driven sea level change drives the majority of Pleistocene shelf sedimentology with regressive shorelines, subarial exposure, and deposition and rework during transgression. Studies suggest that icebergs have grounded along the surface of the New Jersey shelf. Identification of ice-rafted debris (IRD) gives evidence of iceberg movement. By studying the IRD mineralogy, provenance can be assessed. Grab samples collected at sites on the shelf in and around proposed grounding locations are used to identify IRD. Published methods of IRD analysis are available, however those procedures were developed in pelagic waters where fine grains dominate. Thus, we have modified them for application to shelf sediments. Initial mineralogical point count results are the presentation of this study.

First, the coarse grain size fractions of grab samples were separated by phi classes. Next, heavy mineral separation methods were employed to further identify the sediment fractions. Mineral content of each size fraction was then determined by point count. A qualitative assessment of rounding verses angularity was also completed. Finally, this data will be correlated to other studies, including grain size and foraminifera studies.