A teaser indeed!
I may have virtually proved mathematically that Hellas has to be younger than Argyre, Isidis, and Utopia.
Care to submit this paper to the board for, uh.....scrutiny?
I think Greeley and someone else ran simulations in the early 90's on the supercrater antipodal volcanism theory (Hellas, Argyre, Isidis) and concluded that it's not a direct result of the bodywaves moving through the interior of Mars.
I agree that Alba antipodal to Hellas is compelling but PROVING the link is an entirely different ballgame.