Colloquium: Anne Gothmann

Anne Gothmann, JISAO Postdoctoral Associate, School of Oceanography, University of Washington

The major ion and isotopic composition of seawater is sensitive to shifts in geological processes and Earth’s climate. As such, reconstructions of ocean chemistry in the past can help uncover the natural processes that modulate Earth’s environment through time. I will present a new sample set of well-preserved fossil coral that can be used to reconstruct ocean chemistry over the Cenozoic. Fossil coral samples have been examined for diagenesis using both optical and geochemical techniques, and are only used for environmental reconstructions if signatures of diagenetic alteration are absent. I will also show a record of seawater [U] reconstructed from fossil coral samples that shows a factor of ~3-4 increase between the Early Cenozoic and today. While the processes driving this change are currently unclear, possible explanations are connected with ocean carbonate chemistry, low-temperature hydrothermal alteration, and ocean oxygenation.