  We investigate the spallative production of the light elements, Li, Be and B
(LiBeB), associated with the evolution of a superbubble (SB) blown by repeated
SNe in an OB association. It is shown that if about ten percent of the SN
energy can power the acceleration of particles from the material inside the SB,
the observed abundances of LiBeB in halo stars, as a function of O, can be
explained in a fully consistent way over several decades of metallicity. In
this model, the energetic particles (EPs) reflect the SB material, which is a
mixing of the ejecta of previous SNe and of the swept-up ISM gas evaporated off
the shell. We investigated two different energy spectra for the EPs: the
standard cosmic ray source spectrum, or `SNR spectrum', and a specific `SB
spectrum', as results from the SB acceleration mechanism of Bykov & Fleishman
(1992). While the latter spectrum is more efficient in producing LiBeB, the SNR
spectrum can be reconciled with the observational data if an imperfect mixing
of the SN ejecta with the rest of the SB material and/or a selective
acceleration is invoked (enhancing the C and O abundance amongst the EPs by a
factor of ~ 6). One of the main consequences of our model is that the observed
linear growth of Be and B abundances as a function of Fe/H expresses a dilution
line rather than a continuous, monotonic increase of the metallicity. We
propose an observational test of this feature. We also show that the recent 6Li
observations in halo stars fit equally well in the framework of the SB model.
Finally, we conjecture the existence of two sets of low-metallicity stars,
differing in their Be/Fe or B/O abundance ratios, resulting from a `bimodal'
LiBeB production in the Galaxy, namely from correlated (in SBs) or isolated SN
explosions.
