The evolution of the ages and metallicities of massive galaxies since z=0.7

We present results on the stellar population properties of massive galaxies at z = 0.7 based on deep, medium-resolution IMACS spectra for a sample of similar to 70 galaxies in the ECDFS with M-* > 10(10) M-circle dot. The age-mass and stellar metallicity-mass relations for the population as a whole have a similar shape as the local relations over the probed mass range, but offset to ages younger by similar to 4 Gyr and metallicities lower by similar to 0.13 dex. Quiescent galaxies alone have stellar ages and metallicities consistent with passive evolution onto the local quiescent galaxies relations. The evolution in metallicity is driven by star-forming galaxies. However a significant fraction of massive star-forming galaxies have metallicities comparable to those of local quiescent galaxies. If quenched at z < 0.7 they can provide the necessary population to reproduce the scatter in age and metallicity of local quiescent galaxies.