  Recent precise observations of cosmic rays (CRs) by AMS-02 experiment clearly
show (1) harder spectra of helium and carbon compared to protons by $\propto
R^{0.08}$, and (2) concave breaks in proton and helium spectra at a rigidity $R
\sim 300$ GV. In particular the helium and carbon spectra are exactly similar,
pointing to the same acceleration site. We examine possible interpretations of
these features and identify a chemically enriched region, that is, superbubbles
as the most probable origin of Galactic CRs in high rigidity $R>30$ GV. The
similar spectra of CR carbon and helium further suggest that the CRs with
$R>30$ GV originate from the supernova ejecta in the superbubble core, mixed
with comparable or less amount of interstellar medium. We predict similar
spectra for heavy nuclei.
