Radial transport in the solar nebula: Implications for moderately volatile element depletions in chondritic meteorites

In this paper, we explore the possibility that the moderately volatile element depletions observed in chondritic meteorites are the result of planetesimals accreting in a solar nebula that cooled from an initially hot state (temperatures > 1350 K out to similar to 2-4 AU). A model is developed to track the chemical inventory of planetesimals that accrete in a viscously evolving protoplanetary disk, accounting for the redistribution of solids and vapor by advection, diffusion, and gas drag. It is found that depletion trends similar to those observed in the chondritic meteorites can be reproduced for a small range of model parameters. However, the necessary range of parameters is inconsistent with observations of disks around young stars and other constraints on meteorite parent body formation. Thus. Counter to previous work, it is concluded that the global scale evolution of the solar nebula is not the cause for the observed depletion trends. Instead, it appears that localized processing must be considered.