ABSTRACT

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

Hydrothermally altered ocean crust provides a record of heat and mass transfer between seawater and the earth's mantle that takes place during hydrothermal circulation at mid ocean ridges and subduction zones. Hydrothermal vent systems that generate the mineral serpentine are linked to alkaline fluids enriched in organics and are central to generating the energy supply for microbial life at the seafloor. This research uses boron, strontium, and neodymium elemental concentrations as well as boron isotope fractionation to examine the role of water-rock reaction in the conversion of peridotites and other ultramafic rocks common on the seafloor and in the lower crust to serpentine and other minerals. The work involves novel, controlled, hydrothermal, laboratory experiments that examine the pH, temperature and mineral composition controls on boron isotope fractionation and combined B-Sr-Nd mobility and rock-fluid exchange. Targeted geochemical elements were picked because they are recorders of temperature and fluid pH conditions and allow application of the results of the experiments to fossil hydrothermal systems and associated ore deposits. Furthermore, the measurements will constrain the effects of low-temperature serpentinization on the efficiency of elemental recycling across volcanic arcs and enhance our understanding of geochemical fluxes from subducting slabs which impact island arc volcanics. Broader impacts of the work are support of two early career researchers, promotion of a new collaboration, support of students, international collaboration, and support of an institution in an EPSCoR state

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