  Recent work has shown that most globular clusters have at least two
chemically distinct components, as well as cluster-to-cluster differences in
the mean [O/Fe], [Mg/Fe], and [Si/Fe] ratios at similar [Fe/H] values. In order
to investigate the implications of variations in the abundances of these and
other metals for H-R diagrams and predicted ages, grids of evolutionary
sequences have been computed for scaled solar and enhanced alpha-element
mixtures, and for mixtures in which the assumed [m/Fe] value for each of the
metals C, N, O, Ne, Na, Mg, Si, S, Ca, and Ti has been increased, in turn, by
0.4 dex at constant [Fe/H]. These tracks, together with isochrones for ages
from 6 to 14 Gyr, have been computed for -3.0 < [Fe/H] < -0.6, with helium
abundances Y = 0.25, 0.29, and 0.33 at each [Fe/H] value, using upgraded
versions of the Victoria stellar structure program and the Regina interpolation
code, respectively. Turnoff luminosity versus age relations from isochrones are
found to depend almost entirely on the importance of the CNO-cycle, and thereby
mainly on the abundance of oxygen. Since C, N, and O, as well as Ne and S, do
not contribute significantly to the opacities at low temperatures and
densities, variations in their abundances do not impact the Teff scale of red
giants. The latter is a strong function of the abundances of only Mg and Si
(and Fe, possibly to a lesser extent), because they are so abundant and because
they are strong sources of opacity at low temperatures. For these reasons, Mg
and Si also have important effects on the temperatures of main-sequence stars.
Due to their low abundances, Na, Ca, and Ti are of little consequence for
stellar models. The effects of varying the adopted solar metals mix and the
helium abundance at a fixed [Fe/H] are also briefly discussed.
