Jacqueline E. Dixon, professor of geological oceanography at the University of South Florida and DTM Merle A. Tuve Fellow, will give her Merle Tuve Lecture titled, "Light Stable Isotopic Compositions of Enriched Mantle Sources: Resolving the Dehydration Paradox", at 11 a.m. on Thursday, 7 April 2016, in the Greenewalt Lecture Hall.
Dixon received her Ph.D. in geochemistry from California Institute of Technology in 1992. Her research interests focus on the role of H2O and CO2 in the generation and evolution of basaltic magmas with an emphasis on submarine volcanoes.
Abstract: One of the remaining puzzles in mantle geochemistry is the origin and evolution of volatile components. In particular, the “dehydration paradox” refers to the following conundrum. The enriched “prevalent mantle” (PREMA) component found in many mantle plumes requires involvement of a mostly dehydrated slab component to explain the trace element ratios and radiogenic isotopic compositions of PREMA-type oceanic basalts, but a fully hydrated slab component to explain the stable isotopic compositions. I will present new volatile concentration and hydrogen, lithium, and boron isotopic compositions for PREMA- and EM-type oceanic basaltic glasses bearing on this issue. I use these and other published data to develop a comprehensive model for the volatile element, trace element and isotopic compositions of most basaltic melts that resolves the dehydration paradox. This model also accounts for the thermal parameters of slabs in controlling compositions of subduction-derived components in mantle reservoirs.
Coffee, tea, and a continental breakfast will be served before the lecture at 10:30 a.m.