I think the argument really got to him. Maybe it wasn't just that though. Maybe he was stressed out about something else (which is also the most common trigger for random arguments), and your argument was just the last straw.
Then as for his behaviour, I would say that he wanted to be alone, and also he needed to get rid of a pent-up, hard to manage, emotions (hence the banging). He probably felt relieved when you went to the park, because it gave him time to think, but then I guess you came back "too early", so he had to leave to be able to finish thinking stuff through.
I would say let him do his thing and don't bother him until he's calmed down, and then hopefully you can talk it out.