Special Oceanography SeminarMarch 17, 2:30pm - 3:30pm
Mānoa Campus, Marine Sciences Building (MSB) 114
Dr. Katherine Allen*
Columbia University, Frontiers of Science Program
Rutgers University, Institute of Marine and Coastal Sciences
“Ice Ages and Ancient Oceans: Insight from Fossil Foraminifera”
Abstract: Ice age cycles exert powerful influence on Earth's landscape, but the driving mechanisms behind these major climate oscillations remain elusive. Marine sediments constitute a rich archive of ocean history, providing an exciting opportunity to explore the ice age world and to probe the links between ocean chemistry and global climate. In this talk, I will describe my recent work with Foraminifera, unicellular organisms with a wide marine distribution. Many foraminiferal species secrete carbonate shells whose physical and chemical nature reflect the seawater conditions in which they grow. To test environmental controls on the shell incorporation of trace elements, particularly the ratio of boron to calcium (B/Ca), my colleagues and I perform culture experiments with living planktonic foraminifera in Puerto Rico and on Catalina Island, California. Recently, these experiments have confirmed a relationship between B/Ca and seawater pH and revealed additional controls on the B/Ca proxy. Such proxies, when thoroughly tested in the modern ocean, can ultimately be used to reconstruct past ocean chemistry from ancient sediments. In benthic species, B/Ca acts as an indicator of deep water carbonate saturation, and we are currently developing new records from the Southwest Pacific Ocean that provide novel constraints and tantalizing clues to the role of deep ocean CO2 storage in Pleistocene ice age cycles.
*The speaker is a candidate for a faculty position in the Department of Oceanography.
Oceanography, Mānoa Campus