Final stages of breakup and early spreading history of the Eastern North America passive margin from multichannel seismic data
DESCRIPTION: Rifted passive margins record the full geologic history of rifting, from rift onset to continental breakup to the initiation of seafloor spreading and post-rift evolution of the margin. This project focuses on the Eastern North America continental margin offshore Cape Hatteras that was formed after the breakup of supercontinent Pangaea. A large suite of data has been collected across the transition from continental crust to oceanic crust in this region. These data will be analyzed and interpreted to obtain an improved understanding of events surrounding the final stage of continental breakup including the relationship between the timing of rifting and the occurrence of offshore magmatism and early opening of the Central Atlantic Ocean. The project will also provide new information on landslides that have occurred along the margin of the U.S. and an estimate of the number of landslides that might have produced tsunamis. A postdoctoral researcher will be trained in geophysical data analysis and interpretation, and the results of the proposed work will be incorporated into outreach programs for high school and middle school students. This project consists of the processing and interpretation of offshore, long-offset multichannel seismic (MCS) data from the Eastern North American Margin. The long-offset MCS data analysis will provide critical new information about the along-strike variations of the complex transitional crust between unambiguous continental and oceanic crust at a smaller-scale than previous studies. The crustal-scale closely-spaced MCS profiles will be essential to image the small-scale heterogeneities of the volcanic products along the margin, spatial patterns in basement topography, thickness of sediment and rift unconformities within the sediments and features within the crust and lithosphere (e.g., faults and crustal thickness variations). MCS imaging of those features are needed to assess the late-stage rifting processes and variations in time and space of these processes. Different kinematic plate models for the earliest stage of evolution of the Central Atlantic Ocean make very different predictions for the half spreading rate. In addition, large-scale segmentation at the modern Mid-Atlantic ridge has also been proposed to be inherited from the geometry of the adjacent continental margin. MCS data from this project will constrain variations in basement roughness, crustal thickness and crustal structure and reflectivity along and across new oceanic crust that will provide important constraints on the early seafloor spreading history and will help to distinguish between competing models.