Suggestions for links and some content
I actually noticed your page on repatriation right after I made the see also section, it is very closely related!
In terms of indigenous archives, I wasn't going to go into that part of it too much since it is something of a separate issue (and there's already a whole page on first nations archives) but I was going to talk about the issues with them that are shared with other postcolonial archives, one example being the inclusion of Maori records in the New Zealand National Archives and the emphasis on biculturalism in their institution. I'd be happy to see what article you're thinking of though, the issue of postcolonialism are definitely seen in the North American context as well.
The article I'm thinking of is by Matthew Kurtz. I've included the citation for it below!
Matthew Kurtz, “A Postcolonial Archive? On the Paradox of Practice in a Northwest Alaska Project,” Archivaria 61 (2006): 63-90.