  Oxygen abundances [12+log(O/H)] in the interstellar medium of a large sample
of distant (z>0.4) luminous infrared galaxies (LIRGs) were estimated from their
extinction corrected emission-line ratios, on the basis of the VLT/FORS2
spectra with good S/N and moderate resolution. These LIRGs were selected from
ISOCAM deep survey fields (CFRS, UDSR, UDSF). They show oxygen abundances
ranging from 8.36 to 8.93, with a median value of 8.67, which is 0.5 lower than
that of the local bright disks (i.e., L*) at the given magnitude. A significant
fraction of distant large disks are indeed LIRGs. Such massive disks could have
formed ~50% of their metals and stellar masses since z~1.
