Peculiarities of {\alpha}-element abundances in Galactic open clusters
  A catalog compiling the parameters of 346 open clusters, including their
metallicities, positions, ages, and velocities has been composed. The elements
of the Galactic orbits for 272 of the clusters have been calculated.
Spectroscopic determinations of the relative abundances, [el/Fe], for 14
elements synthesized in various nuclear processes averaged over data from 109
publications are presented for 90 clusters. Since no systematic effects
distorting the relative abundances of the studied elements in these clusters
have been found, these difference suggest real differences between clusters
with high, elongated orbits and field stars. In particular, this supports the
earlier conclusion, based on an analysis of the elements of the Galactic
orbits, that some clusters formed as a result of interactions between
high-velocity, metal-poor clouds and the interstellar medium of the Galactic
thin disk. On average, clusterswith high, elongated orbits and metallicities
${\rm [Fe/H]} < - 0.1$ display lower relative abundances of the primary \'a
elements than do field stars. The low [O,Mg/Fe] ratios of these clusters can be
understood if the high-velocity clouds that gave rise to them were formed of
interstellar material from regions where the star-formation rate and/or the
masses of Type II supernovae were lower than near the Galactic plane. It is
also shown that, on average, the relative abundances of the primary
$\alpha$-elements are higher in relatively metal-rich clusters with high,
elongated orbits than in field stars. This can be understood if clusters with
${\rm [Fe/H]} > - 0.1$ formed as a result of interactions between metal-rich
clouds with intermediate velocities and the interstellar medium of the Galactic
disk; such clouds could form from returning gas in a so-called "Galactic
fountain".
