  The Spitzer Adaptation of the Red-sequence Cluster Survey (SpARCS) is a
z'-passband imaging survey of the 50 deg^2 Spitzer SWIRE Legacy fields,
designed with the primary aim of creating the first large, homogeneously
selected sample of massive clusters at z>1. SpARCS uses an infrared adaptation
of the two-filter cluster red-sequence technique. In this paper we report
Keck/LRIS spectroscopic confirmation of two new exceptionally rich galaxy
clusters, SpARCS J161315+564930 at z=0.871+/-0.002, with 14 high-confidence
members and a rest-frame velocity dispersion of sigma_v= 1230+/-320 km s^-1,
and SpARCS J161641+554513 at z=1.161+/-0.003, with seven high-confidence
members (including one AGN) and a rest-frame velocity dispersion of
sigma_v=950+/-330 km s^-1. We also report confirmation of a third new system,
SpARCS J161037+552417 at z=1.210+/-0.002, with seven high-confidence members
and a rest-frame velocity dispersion of sigma_v=410+/-300 km s^-1. These three
new spectroscopically confirmed clusters further demonstrate the efficiency and
effectiveness of two-filter imaging for detecting bona fide galaxy clusters at
high redshift. We conclude by demonstrating that prospects are good for the
current generation of surveys aiming to estimate cluster redshifts and masses
at z>~1 directly from optical-infrared imaging.
