If the label says nothing about Dutched or alkalized, then it isn't. It has the antioxidants that are beneficial.
I do know that Lindt, a Swiss manufacturer of chocolate, bought Ghirardelli a few years back. A lot of Lindt's dark chocolate products are alkalized, as are most European dark chocolates. That may be why I get a headache when I eat them. I don't get that reaction from Ghirardelli or Hersey's dark chocolates.