This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-2).
Deciphering the origins of the giant large igneous provinces is a critical element for understanding mantle dynamics and its relation to terrestrial magmatism. Among a dozen or so large oceanic plateaus in the oceans Shatsky Rise is an important target because of its unique tectonic setting. It is the only giant plateau formed at a time of frequent magnetic reversal anomalies that show its relationship to coeval spreading ridges. IODP Expedition 324 is currently also scheduled to sample the sediments and upper igneous layers at five sites on Shatsky Rise in late 2009, which could provide important ground-truthing. The PIs propose a collaborative geophysical project with two foci: (1) constraining the crustal structure by an OBS reflection and refraction experiment, and (2) delineating the tectonic history by MCS profiling and reanalysis of bathymetry and magnetic data. A new model of crustal seismic structure will constrain the nature of mantle melting on the basis of correlation between thickness and velocity. The detailed upper crustal structure revealed by MCS will help to reconstruct the tectonic history of Shatsky Rise, which appears to be a huge volcano formed at a triple junction and then split apart by seafloor spreading. The PIs will synthesize the results of these geophysical studies to build a comprehensive tectonic framework, including better estimations of eruption rate, its temporal variation, its relation to ridge kinematics, and the coeval evolution of the parental mantle.
International collaboration with the Japanese and Russian scientists and graduate and undergraduate students training and sea-going experience are some of the broader impacts of the study. Outreach to school students is also planned.
