In Yes' "Close to the Edge" (the song), there's a fast keyboard riff towards the end with the rest of the band playing accompaniment. But what I find odd is how keyboardist Rick Wakeman persistently plays an F♯ whereas the music is in A Aeolian (A minor) at that point in the song.
It's as if the band is combining two modes, Aeolian (on A) and Lydian (on C), or some "new" modified Aeolian mode with a ♮6. (♯♭6?)
Is there a name for this mode? Or is it just a "mashup" of two simultaneous modes?
Even more odd is how Wakeman keeps hitting the F♯ even when the rest of the band plays a D minor chord (15:20 in the "non-video" linked above).