MORB Construction Processes: Plutonic to Volcanic Connections in Plagioclase Ultraphyric Basalts (PUBs)

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The compositions of mid ocean ridge basalts (MORBs) and related volcanic rocks are one of the primary observational datasets used to illuminate melting processes that ultimately lead to formation of ocean crust and processes like global geochemical cycling and plate tectonics. Most MORB, however, is modified by processes that occur in the upper mantle and oceanic crust. To constrain the processes that modify the composition of MORB during its residence and transit from the mantle through the oceanic crust, this research will carry out a geochemical and textural study of plagioclase-rich MORB from ultra-slow and intermediate spreading-rate mid ocean ridges. The focus of the work will be on plagioclase from plagioclase-ultraphyric basalts. This mineral is a potentially rich and largely unexploited recorder of magma temperature, composition, mass balance and time. Analytical work will include a combination of in situ analytical chemical and isotopic analysis techniques, analyses of major and trace element compositions of the lavas, textural studies, determination of trace element diffusion profiles, crystal size distributions, and other approaches. Broader impacts of the work are support of a student and an early career faculty member.