IRG systems, page-8

I think there's an explaination for how IRGs form @jimmypossum.

Almost the entirety of Australia's east coast - not just the ground this ASX ticker holds. This east coast was glacial at the time of the supposed 'intrusion'. It helped a lot i think. This area going glacial late in its tectonic formation.

So is this the reason why the "boffins" can't explain it. New textbooks on granite 'formation' need to be written first...