Recent Ridge Eruptive Activity Dating and Investigations - 2: Lava Geochronology and Mantle Melting (The "RREADI-2" Project)

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This project is a 3-year study of very recent (last 100 yrs or so) eruption chronology and lava geochemistry at mid-ocean ridges to better understand volcanic, hydrologic and biological processes at some of the world's most-active submarine volcanoes. The temporal variability of processes occurring at the mid-ocean ridge system is a key component for understanding the dynamics of these globally important volcanic structures and how they affect terrestrial environments. Eruption chronology will be determined from analyses of naturally-occurring radioactive elements in the lavas and by applying actinide-series disequilibrium techniques. Part of this work will use established techniques but part of the project involves development of new rock dating tools to further our reach back in time. The work plan is composed of three aspects to be conducted semi-concurrently:[1] be "RREADI" to date very young (0 to 1.5 yrs since eruption) rocks for eruption verification in our existing facility using the 210Po-210Pb technique.[2] investigate 210Pb- 226Ra for use as a chronometer over the 1-100 yr time scale and apply it to lavas from areas of recent mid-ocean ridge eruptions.[3] investigate variability in magmagenetic conditions in the sub-ridge mantle associated with the most-recent mid-ocean ridge eruptions by measurements and data modeling of longer-lived actinide series isotopes.