Graduation Year

2023

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Marine Science

Major Professor

David F. Naar, Ph.D.

Committee Member

Alastair G. C. Graham, Ph.D.

Committee Member

Mark E. Luther, Ph.D.

Keywords

Multibeam Backscatter, Foundation Seamounts, Seafloor Prospecting, Benthic Habitat Mapping

Abstract

Occurrences of nodules on the seafloor represent benthic habitats and present potential deposits of economically important metals. Better understanding their extent throughout Earth’s oceans will aid in resource management and determining different factors which influence their formative factors and respective local characteristics. Multibeam bathymetry and backscatter data, along with auxiliary data suggest an area of seafloor near the Foundation Seamount chain in the southern Pacific Ocean, centered around -36.84° latitude, -119.75° longitude, contains a previously uncharted polymetallic nodule occurrence. Our analysis of Simrad EM12 DUAL (12 kHz) multibeam data, collected during a 1997 transit, shows an area of strong backscatter strength in a bathymetric setting conducive for polymetallic nodule formation (based on regional environmental parameter analyses). Our results suggest nodule presence provides the most reasonable explanation for the observed strong backscatter data. Analysis considers thresholds for a conducive environment for nodule presence including seafloor slope, depth, sedimentation rate, seafloor age, and compares these criteria against backscatter data from a case study data set of 12 kHz transit multibeam data. The methods described may assist with locating other potential nodule habitats from archived 12 kHz multibeam data in the global ocean basins, and assist in discriminating seafloor habitat types. Efforts in collecting future multibeam data in the global oceans (e.g., Nippon Foundation – GEBCO Seabed2030 project), should also consider the potential applications of seabed habitat identification and locating resources from future multibeam backscatter data.

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