Vibracoring on the New Jersey Shelf: Investigating the Stratigraphic Response to approximately 50,000 Years of Eustasy

摘要

Our primary objective was to sample shallow stratigraphic targets on the New Jersey middle and outer continental shelf. The goal was to establish the geologic history of sedimentary processes on the New Jersey shelf over the last approximately 50,000 years, particularly focusing on the nature of shelf- edge sedimentary wedges, including the formation and preservation of sand bodies, the paleoclimate associated with outer shelf channel formation and subsequent infilling, cross-shelf transport of sediments at or near lowstand, and the influence on the preserved stratigraphy of large sediment outflows associated with postulated glacial lake collapses during the last deglaciation. By interacting with ONR-funded acoustic programs on the New Jersey shelf, we sought to provide the capability for modeling geoacoustic properties of the shallow seabed in three dimensions. Our original plan called for collecting cores using the AHC-800 (Active Heave Compensation to 800 m) drilling system, which was developed and is operated by the DOSECC (Drilling, Observation and Sampling of the Earth's Continental Crust) consortium. Unfortunately, DOSECC pulled out of the contract just a few months prior to the cruise. After consulting with our sponsors and collaborators, we decided to press on with the cruise using a commercial vibracoring system. This option was attractive for two reasons: (1) we would be able to attempt to core in many more locations (perhaps 10 times as many) than would have been possible with the AHC-800, and (2) with our vast collection of chirp seismic data, we could pinpoint erosional windows that would allow us to sample most of our target strata with shorter cores, avoiding in most locations the difficult-to-recover Holocene sand layer.