  Employing a Monte-Carlo based evolutionary code, we show that the delay of Fe
deposition relative to O, due to the incorporation of supernova ejecta
refractories in high velocity grains, can account for the rise of [O/Fe] with
decreasing [Fe/H]. The predicted behavior of refractory Mg, Si, Ca and Ti, and
volatile S, namely that the refractories should not show the rise, but that the
behavior of S should be similar to that of O, appears to be confirmed (Takeda
et al. 2000, astro-ph/0007007). The delayed deposition of Be, due to cosmic ray
transport in a relatively low density medium, leads to consistency of primary
Be evolution as a function of both [Fe/H] and [O/H].

Astrophysics