Paper:	Photochemical Speciation of Oxygen Isotopes in the Solar Nebula
Volume:	341, Chondrites and the Protoplanetary Disk
Page:	193
Authors:	Lyons, J.R.; Young, E.D.
Abstract:	We have performed time-dependent photochemical calculations of CO self-shielding in the surface region of a turbulent nebula, and demonstrated that substantial mass-independent fractionation in bulk oxygen isotopes in the nebula was possible on timescales of 105 years. CO photodissociation in the presence of abundant H2 yields δ-values for nebular H2O with δ 17O/δ 18O near 1.0, consistent with measurements in Ca-Al-rich inclusions. This mechanism provides a self-consistent explanation for the oxygen isotope values of nebular water inferred from secondary minerals in unequilibrated chondrites, and places constraints on the far-ultraviolet radiation in the solar nebula environment and the strength of turbulent vertical mixing in the nebula.

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