Emission-line abundances of absorption-selected galaxies at z < 0.5

We have obtained optical spectra of four galaxies associated with MgII quasi- stellar object (QSO) absorbers at redshifts 0.10 < z < 0.45. We calculate the gas- phase oxygen abundance of these galaxies using the empirical R-23 strong- line method. The absolute B- band magnitudes of the galaxies span - 20.6 < M-B < -18.3. If the metallicities lie on the R-23 upper branch (8.4 < log (O/H) + 12 < 8.9), then the metallicities of these absorption- selected galaxies span the range between 0.5 and 1.4 Z. and would be consistent with the well- known luminosity- metallicity relation for 0.10 < z < 0.45 emission- line galaxies. However, such metallicities would be 0.5- 1.0 dex higher than those observed in damped Lyman alpha systems (DLAs) via absorption-line measurements at similar redshifts. Conversely, the lower R-23 branch calibration yields metallicities Z similar to 1/7 Z., consistent with the DLA absorption metallicities at low redshifts. In this case, the absorption- selected galaxies would lie significantly lower than the luminosity-metallicity relation for emission- line galaxies at z < 0.5. We discuss the implications and possible solutions for each scenario.