  The absolute generalized cross sections and angular distribution parameters
of photoelectrons for the two-photon above threshold $3p$-ionization of Ar were
calculated in the exciting photon energy range from 15.76 to 36 eV. The
correlation function technique developed earlier was extended for the case when
an intermediate-state function is of a continuum-type. We show that two-photon
ionization of Ar near the $3p^{4}$ threshold to a large extent is determined by
the $(3p\dashrightarrow\varepsilon d)^{2}$ two-photon absorption via the giant
resonance. This many-electron correlation causes (i) an increase of the
photoionization cross sections by more than a factor of 3; (ii) the appearance
of resonances in the exciting-photon energy range of the doubly-excited states.
The predictions are supported by a good agreement between length and velocity
results obtained after taking into account of the higher-order perturbation
theory corrections.
