  We present the results of combined optical and near-infrared photometry for
the globular cluster systems of the giant ellipticals IC 4051 and NGC 3311. We
use the reduced age-metallicity degeneracy in (V-I) vs.(V-H) color-color
diagrams to derive the cumulative age distribution within the red
sub-population of globular clusters and to search for age sub-populations. The
age distribution is then compared to the one determined for simulated globular
cluster systems in order to set constraints on the relative age and size of
these globular cluster sub-populations. In both galaxies we find a significant
fraction of globular clusters with ages between 2- 5 Gyr. We also investigate
the metallicity distribution in both systems. Small number statistics prevent
us from making any definite statements concerning NGC 3311, but we find that
the derived metallicity distribution of the IC 4051 clusters strongly depends
on the assumed age distribution. Based on our most likely result that finds a
large number of young/intermediate age clusters (~2 Gyr) within the selected
globular cluster sample, we find metallicity peaks at $\sim$ -0.2 for the old
clusters and +0.8 for the young clusters. Only few very metal poor clusters are
found. However, the metallicity distribution within the young/intermediate
globular cluster population is significantly affected by our choice of the
applied Single Stellar Population model. The mean metallicity of the second
generation of globular clusters changes from the above mentioned and extremely
high +0.8 dex to +0.2 dex. Note that the model dependency becomes less severe
with an increasing age of the cluster population.
