  We assess supernova (SN)-driven pregalactic outflows as a mechanism for
distributing the product of stellar nucleosynthesis over large cosmological
volumes prior to the reionization epoch. SN ejecta will escape the grasp of
halos with virial temperatures T_vir>10^{4.3} K (corresponding to masses M>10^8
h^{-1} M_sun at redshift z=9 when they collapse from 2-sigma fluctuations) if
rapid cooling can take place, and a significant fraction of their baryonic mass
is converted into stars over a dynamical timescale. We study the evolution of
SN-driven bubbles as they blow out from subgalactic halos and propagate into
the intergalactic medium (IGM), and show that to lift the halo gas out of the
potential well the energy injection must continue at least until blow-away
occurs. The collective explosive output of about ten thousands SNe per halo at
these early epochs could pollute vast regions of intergalactic space to a mean
metallicity <Z>=Omega_Z/Omega_b>0.003 (comparable to the levels observed in the
Lyman-alpha forest at z=3) without much perturbing the IGM hydrodynamically,
i.e. producing large variations of the baryons relative to the dark matter. The
volume filling factor of the ejecta is higher than 20% if the star formation
efficiency is of order 10%. When the filling factor of the ejecta becomes
significant, enriched material will typically be at a higher adiabat than
expected from photoionization.
