Geological Interpretations of a Low-backscatter Anomaly Found in 12-kHz Multibeam Data on the New Jersey Continental Margin

TitleGeological Interpretations of a Low-backscatter Anomaly Found in 12-kHz Multibeam Data on the New Jersey Continental Margin
Publication TypeThesis
Year2008
AuthorsSweeney, E
Degree and ProgramMaster of Science
DegreeEarth Sciences/Ocean Mapping
Number of Pages167
Date Published12/2008
UniversityUniversity of New Hampshire
LocationDurham, NH
Keywords12-kHz multibeam data, continental margin, low-backscatter, new jersey

A low-backscatter acoustic anomaly was recently mapped on the New Jersey continental margin between Hudson and Wilmington channels using a 12-kHz multibeam echo-sounder (MBES). The presence of the low-backscatter anomaly indicates a change in the physical properties of the seafloor or near sub-surface. Analyses of seafloor and sub-surface acoustic data with previously collected sediment cores suggest three hypotheses as possible geological causes for the anomalously low-backscatter strength: (1) a sediment deposit, (2) an outcrop of sediment strata due to sediment removal and non-deposition, or (3) the presence of gas in the sub-surface sediments. Multibeam bathymetry and backscatter data, high-resolution 3.5-kHz chirp sonar profiles, airgun single-channel seismic-reflection profiles, and sediment cores collected nearby the low-backscatter anomaly most strongly support the hypothesis that the low-backscatter anomaly is an outcrop of older sediments that have been exposed by Western Boundary Undercurrent (WBUC) erosion and non-deposition induced by local seafloor morphology.