Effect of Melt Supply on MORB Compositions at Local and Regional Scales

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Submarine mid-ocean ridges are the most volcanically active places on the planet. Lavas erupted from them cover roughly 2/3 of the Earth's surface. This volcanism is a major outlet for heat and matter in Earth's interior and plays a significant role in ocean chemistry and the ecology of the seafloor life. This research evaluates processes responsible for variations in erupted lava compositions that occur at the regional (100-1000 km) to local (10-100 km) length scales and that operate over decades to millennia. Using data mining techniques, global databases of seafloor volcanic rock compositions, and statistical analysis, the work seeks to determine coupled variations in magma differentiation, magma mixing, and mantle source composition. Constraints on timescales will be determined from published radiogenic U-series dates as well as new radiogenic dates that will be determined on key rock samples. Work focuses on study sites where melt supply has recently varied in time or space over a range of volcanic conditions and where rock samples and compositional data are already in hand. The importance of the work is that it sheds light on the magnitude and temporal-spatial variability of movement of material and heat from Earth's interior to its surface, with attendant implications for how Earth's crust is constructed and environmental change in the deep oceans. Broader impacts of the work include international collaboration, student training, and support of an institution in an EPSCoR state (Hawaii).