We have obtained Keck spectra of six candidate globular clusters ( GCs ) in the dynamically young elliptical galaxy NGC 3610 , supplementing our previous Keck spectra of eight confirmed GCs ( Strader et al. 2003 ) .
Five of our new candidates are confirmed to be GCs .
Of the thirteen GCs , eleven are located within the K band effective radius of 7 kpc .
Two of these thirteen clusters are found to be young ( \sim 2 Gyr ) and very metal-rich ( [ Z /H ] \sim +0.5 ) , three are old and metal-poor , and the remaining eight clusters are old and metal-rich .
The ages of the young clusters are consistent with a recent spectroscopic age estimate of 1.6 \pm 0.5 Gyr for the galaxy itself ( Denicolo et al. 2003 ) and suggest that these clusters formed in the disk-disk merger which likely created NGC 3610 .
Intriguingly , both young GCs have [ \alpha /Fe ] \sim + 0.3 , while the majority of the old clusters are not \alpha -enhanced , in contrast to Galactic and M31 GCs , and contrary to predictions of nucleosynthetic calculations .
The two old subpopulations of GCs can be attributed to the merger progenitors .
The relative numbers of old and new metal-rich GCs are poorly constrained because of the expected differences in radial distributions of the two subpopulations .
However , based on our spectroscopic results and a comparison of the Hubble Space Telescope 
color magnitude diagram ( Whitmore et al. 2002 ) with stellar population models , we argue that more than half of the metal-rich GCs are likely to be old .