Collaborative Research: Neogene history of mass transport deposits offshore North Carolina

Submarine landslides are a common seafloor feature of the North Atlantic passive margin on both sides of the ocean; their presence on the Eastern North American Margin is the rule rather than the exception. They threaten large population centers along these coasts with possible tsunamis, and move material from the shallow to the deep sea during margin evolution. Despite their high prevalence on passive margins and in particular, on the U.S. east coast, very little about their causes, mechanical behavior, and frequency is understood, and their role in the development of the passive margin as it exists today has not been examined. This project will collect new seismic data with the R/V Marcus Langseth to examine large submarine landslide behavior over the past 23 million years in a region offshore North Carolina that has experienced large, recent submarine landslides. Sediment cores will be retrieved from the Cape Fear Slide, which is the most recent large submarine landslide in the area and still expressed on the seafloor. The cores will provide insights into pre-conditioning and triggering mechanisms. This study will improve understanding of how slope failures operate through time and the manner in which past events might influence subsequent events, and will provide training and international collaboration opportunities for three graduate students and three early-career scientists.

This project will collect high-resolution multichannel seismic data and piston cores on the continental rise and slope in the vicinity of the Cape Fear submarine landslide offshore North Carolina. These data will be used to examine the interplay between margin topography, fluid and heat flow, pore pressure, and submarine mass transport deposits. Mass transport deposits, bottom-simulating reflections, and stratigraphic sequences in the Cape Fear region will be seismically imaged. The new high-resolution seismic data will be combined with existing seismic and borehole data to interpret number of events, timing, source areas, volumes, areal extent and runout length, and bounding surfaces of mass transport deposits. The seismic data will be used to assess and model internal characteristics of mass transport deposits and surrounding sediments, including deformation style, present-day pore pressure and temperature distribution, and the presence of gas. This project consists of acquiring 3843 km of 2D high-resolution multichannel seismic data, along with bathymetry, subbottom profiler, and water column data. Seven piston and seven gravity cores will be collected in locations associated with seeps or bottom-simulating reflections. Geotechnical and pore fluid chemical analyses will be performed. The processed seismic data will be interpreted for stratigraphic age control, areal extent, and volume of mass transport deposits. Internal deformation of mass transport deposits will be examined through seismic attribute analysis. Sediment physical properties will be derived using full waveform inversion and quantitative models of conditions for failure will be developed. The results of this project will be relevant to understanding submarine landslides dynamics on passive margins with similar characteristics worldwide.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.