IGPP Seminar Series

Inferring photochemical environments from oxygen and sulfur isotope fractionation in rocks

by James Lyons
IGPP, UCLA

Abstract

Over the last several years photochemical processes have been suggested to be responsible for the oxygen isotope distribution of refractory minerals in primitive meteorites, and also for the sulfur isotope signatures of Archean sedimentary rocks. The former is believed to bear witness to the formation environment of the solar system, and the latter to the rise of oxygen in Earth?s atmosphere. The key isotopic processes are CO photodissociation in the solar nebula for the meteorite minerals, and SO2 photodissociation in the ancient Earth atmosphere for the sedimentary rocks. I will present modeling work that supports both of these scenarios. Recent experiments have been published that argue against these photochemical interpretations. I will discuss these experiments and demonstrate that they are either grossly inadequate or are being incorrectly interpreted.
Tuesday, 17 November 2009
3853 Slichter Hall
Refreshments at 3:45 PM
Lecture at 4:00 PM