Lateral Variations in Seismic Structure of Atlantis Massif Oceanic Core Complex

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-2).Oceanic core complexes (OCC) expose intrusive mafic rocks and lenses of mantle ultramafic rock, that are controlled by long-lived detachment faulting within the axial zone of a spreading center. The PI will analyze existing MCS OBS data at Atlantis Massif and the structural insights gained from detailed analysis of this oceanic core complex will allow her to compare it with other core complexes. Based on consistencies between the sites, or lack thereof, she will test current models of OCC formation and evolution. The existing seismic data at Atlantis Massif will allow the PI to document fairly detailed structure (several 10's m vertical resolution) within the upper ~1.5 km and broader scale structure (few-hundred meters vertical resolution) to lithospheric depths of 4-7 km. By combining MCS and OBS refraction data, she will obtain a velocity model along a grid of lines that cover each structural component of this OCC. The resulting tomographic model will allow her to determine the extent and continuity of likely mafic intrusive bodies, to characterize the transition between these bodies and crust that has normal velocity-depth properties, and to compare the signature of the domal core of the OCC to that of the adjacent hanging wall and conjugate outside corner crust. The project is large part for the support of a graduate student for the completion of a Ph.D. thesis. It will also allow further development of the SOBE processing system for MCS refraction analysis, a major community service, and it may help in future drilling on the Atlantis Massif.