Special Lamont75 Earth Science Colloquium, where eminent alumni and former staff showcase their research and reflect on what makes LDEO special presents:
Dr. Dr. Frank Pavia, Assistant Professor, University of Washington.
Abstract:
The oceanic crust and marine sediments are exposed to pure and chemically altered seawater. Fluid-rock interactions between these reservoirs provoke a wide variety of chemical reactions that modify the physical and chemical properties of both the fluids and the solids involved, with implications for the global cycles of water, carbon dioxide, and fluid-mobile elements in Earth’s surface and interior. Uranium is a powerful tracer of weathering reactions at the seafloor because it is highly soluble in its oxidized form in seawater, and undergoes two flavors of isotopic fractionation: one during water-rock interaction, and one during redox transitions between U(VI) and U(IV). In this talk, we show how uranium isotopes can be used to fingerprint weathering dynamics in serpentinites and in marine sediments. We use our results to show that low-temperature weathering of oceanic serpentinites by chemically evolved seawater is pervasive at the seafloor, and that continental serpentinites host unique uranium isotope signatures driven by the grain size of U hosting minerals. We investigate the role of iron oxides as mineralogical hosts for uranium in seafloor serpentinites and discuss possible implications for the whole-earth uranium isotope cycle.
Host: Dr. Robert Anderson, Ewing-Lamont Research Professor, Geochemistry, LDEO; Jennifer Middleton, Lamont Assistant Research Professor, Geochemistry, LDEO.
The Earth Science Colloquium Series, sponsored by Lamont-Doherty Earth Observatory and Columbia University Department of Earth and Environmental Sciences (DEES), provides a lively forum for discussing a wide variety of topics within the Earth sciences and related fields. Colloquia are attended by the full range of scientific and technical staff at LDEO. Colloquium attendance is required of all pre-orals DEES graduate students. The Colloquium Series supports the Lamont Seminar Diversity Initiative.
