  We investigate the origin of the abundance variations observed among
similarly aged F and G dwarfs in the local Galactic disk. We present arguments
in support of combined infall of metal-deficient gas and sequential enrichment
by successive stellar generations in the local Galactic disk ISM. We show that
galactic chemical evolution models which take into account these processes
simultaneously are consistent with both the observed abundance variations among
similarly aged dwarfs in the solar neighbourhood and the abundances observed in
the local disk ISM. For reasonable choices of parameters, these models can
reproduce variations in [M/H] for individual elements M = C, O, Fe, Mg, Al, and
Si as well as the scatter observed in abundance-abundance relations like
[O/Fe]. For the same models, the contribution of sequential stellar enrichment
to the magnitude of the observed abundance variations can be as large as 50%.
We discuss the impact of sequential stellar enrichment and episodic infall of
metal-deficient gas on the inhomogeneous chemical evolution of the Galactic
disk.
