Wow, that's nice work! Now I remember where I've seen this before: There was a dust-up a couple years ago on another board about HDTracks selling files that weren't exactly as advertised - they were selling some albums as 24bit/88.2kHz, and when you looked at the spectrograms they looked similar to what we're talking about here. It turns out they were 44.1kHz files that were padded to 88.2kHz.
I hope you don't mind, I shared your results over on GS with the person who recorded this. Thanks so much for helping to clear that up!