EES Virtual Seminar: Elevated Fe oxidation states, like H2O and select trace elements, are linked to material recycling in Izu-Bonin-Mariana lavas in space and time
Dr. Maryjo Brounce, University of California Riverside
Abstract: Elevated water and select trace element concentrations, as well as higher Fe3+/TFe ratios, distinguish arc basalts from mid-ocean ridge basalts. It is broadly accepted that the elevated water contents and certain incompatible trace element abundances are linked to the presence of fluids and/or melts from subducting ocean slabs, but recently, the reason for elevated Fe3+/TFe of arc basalts has been more controversial. In this talk, I will show measurements of major, trace, and volatiles contents and Fe3+/TFe ratios of submarine glass and olivine hosted melt inclusions from Izu-Bonin-Mariana system that sample 1) a range of extent of influence from the subducting Pacific plate from the back-arc to the central arc, and 2) various stages of the lifetime of the system, from initiation of the margin ~52 Ma to present day. Despite changes in crustal thickness, major element chemistry of mafic lavas, and dissolved sulfur contents in silicate glass in both space and time, erupted samples with Fe3+/TFe ratios higher than typical MORB always have elevated water and select trace element contents. This coherence for all erupted samples from the Eocene to present day and from the back-arc to the well-established arc volcanoes strongly links the production of oxidized, hydrous lavas with the release of fluids and/or melts into the mantle in the IBM system.
Online via Zoom
(Please contact the department at email@example.com for the Zoom link.)