A COMMUNITY SEISMIC EXPERIMENT IN THE ENAM PRIMARY SITE (Invited Presentation)

ENAM was chosen as a GeoPRISMS Rift Initiation and Evolution primary site because it represents a mature continental margin with rift basins that preserved a record of extension and continental breakup. The degree to which syn-rift magmatism and preexisting lithospheric weaknesses controlled the evolution of the margin can be investigated if we image its 3-D structure at small and large length scales with active-source and earthquake seismic methods. In the Summer of 2012 we submitted a proposal to the US National Science Foundation for an ambitious plan for data acquisition on a 400 km-wide section of the mid-Atlantic East Coast margin around Cape Hatteras, from unextended continental lithosphere onshore to mature oceanic lithosphere offshore. This area includes an important along-strike transition in the morphology of the margin from the Carolina Trough to the Baltimore Canyon Trough, and two major marine fracture zones. The study area also covers several features representing the post-rift modification of the margin by slope instability and fluid flow. As the Earthscope Transportable Array reaches the East Coast in 2013 and 2014, the community will have an unprecedented opportunity to image the structure of the rifted margin. To make effective use of the seismic vessel R/V Marcus Langseth, Earthscope seismic instrumentation, and US OBS Instrument Pool, we have proposed to collect onshore/offshore, active and passive seismic data at the mid-Atlantic margin in the context of a community-driven experiment with open data access. If funded, we would seek further community input to refine the experiment plan to best meet the needs of the diverse GeoPRISMS and Earthscope communities. We have proposed an integrated education effort during and after acquisition. The data acquisition teams will largely consist of young scientists, who will be chosen by application. Shortly after cruise, we have proposed to hold short courses on multichannel seismic reflection and wide-angle reflection and refraction data processing using the new seismic data. The permitting, acquisition, archiving and distribution of all seismic data will take two years. Afterwards, proposals developed by any member of the science community can be submitted for further data analysis and investigations of the evolution and dynamics of the ENAM margin.